Carbon-Based Nanomaterials in Biosystems: Biophysical Interface at Lower Dimensions

Carbon-Based Nanomaterials in Biosystems: Biophysical interface at Lower Dimensions provides a thoroughly comprehensive overview of all major aspects of carbon-based nanomaterials, their biophysical response, and biotechnological application. 

The book articulates the underlying physics, chemistry, and the basic phenomenon of the broad-range carbon-based nanomaterials (CNMs) with the biological systems particularly the interface analysis.

Organized in six sections, it discusses state-of art technological interventions of carbon-based nanomaterials and their application in biomedical sectors in healthcare, food sciences, and technology. The book also highlights the carrying capacity of different CNMs in payload efficiency mechanisms in various biomedical fields. The theranostic efficiency and the safety of various forms of CNMs is assessed. Carbon-Based Nanomaterials in Biosystems is a helpful resource to those specializing in the areas of nanomedicine, bionanomaterials and nanotechnology applications.

• Covers major breakthroughs in carbon nanomaterials (CNMs)
• Distinguishes between the advantages and disadvantages of carbon-based and non-carbon-based nanomaterials
• Discusses the significance of different forms of carbon nanomaterials and their unique physico-chemical and electrochemical properties at the lower dimension
• Examines the appropriate methodologies for tackling safety and health-related matters while using carbon-based nanomaterials
• Discusses recent developments of various forms of carbon-based nanomaterials such as graphene, carbon nanotubes, fullerenes, and carbon nano-onions

• Language: English
• Publisher: Academic Press
• Release date: Apr 24, 2024
• ISBN: 9780443155093

Book preview

Introduction

Kunal Biswas, Yugal Kishore Mohanta, Tapan Kumar Mohanta and Muthupandian Saravanan

Nanotechnology is envisaged as the next significant breakthrough in the fields of biomedical sciences and molecular electronics, to name a few. Over the last several decades, robust and extensive research has been performed to advance the exploration and utilization of novel and unique nanomaterials for different biotechnological and biomedical purposes. In the domain of healthcare and associated biomedical fields, carbon-based nanomaterials and their families seem to play a critical role in bringing revolutionary advances. In recent decades, a significant number of innovative ideas utilizing novel and significant nanomaterials have been implemented in biotechnological applications on an annual basis. It is further noticed that an exponential rate of growing numbers of emerging businesses are actively seeking market opportunities through the utilization of these advanced technologies and features. This publication functions as an interdisciplinary forum that showcases cutting-edge, multidisciplinary research and technological advancements in theory, instrumentation, and methodologies, along with their applications in various areas and types of carbon-based nanotechnology pertaining to diverse areas from biomedical sciences to agricultural sciences and biosensing aspects. This publication provides an overview of the fundamental principles, current applications, and recent advancements in nano-biotechnological research, with special reference to carbon-based nanomaterials and their biosystem interactions taking place at the lower dimensions. Additionally, it offers insights into the future prospects of nanobiotechnology. A significant amount of progress has been made in the last several decades. However, there is a pressing need for a comprehensive update to address the existing gaps and present a thorough analysis of the advantages and disadvantages of various methods and principles for practical implementation by individuals. This book has been developed through extensive surveys of the field, incorporating insights from various disciplines, including biotechnology, bioorganic and bioinorganic chemistry, materials science, nanotechnology, and bioanalytics. The aim is to provide a comprehensive overview of current and future developments in this area. This version also includes comprehensive references to the latest 10 years of nanotechnology and biotechnology research.

The book titled Carbon-based Nanomaterials in Biosystems: Biophysical Interface at Lower Dimensions explores both the practical and theoretical implications of diverse carbon-based nanomaterials and their biological interactions at lower dimensions. The exceptional physicochemical properties and associated unique characteristics of this family of materials enable its applications in various fields, including biosensing, food sciences, health sectors, and agricultural domains, and we evaluated the underlying molecular basis of interactions at the biophysical interface. This book is classified into six sections consisting of 21 chapters that are dedicated to the new developments and prospects of different carbon-based nanomaterials and their biological interactions in the lower dimensions.

Section 1: Carbon-based Nanomaterials: Fabrication, Manufacture, and Underlying Physicochemical Properties

Different aspects of recent state-of-the-art techniques employing bottom-up and top-down methods have been discussed for the diverse family of carbon-based nanomaterials such as graphene, carbon nanotubes, and fullerenes.

Section 2: Carbon-based Nanomaterials in Food Industry

The utilization of carbon-based nanomaterials in the field of food biotechnology has been extensively researched and documented through various recent examples and reviews. This section primarily discusses the various implications of a diverse family of carbon nanomaterials in food sciences and industry. It highlights the advantages and challenges of using nano-scaled carbon materials at lower dimensions in these sectors.

Section 3: Role of Carbon-based Nanomaterials in Agriculture

Different features of carbon-based nanomaterials, encompassing carbon nanotubes, graphene, fullerenes, etc., have been thoroughly discussed and reviewed in the context of myriad agricultural-related issues and applications. The field of interest in the agricultural domain ranges from pesticide management matters to crop-biosensing aspects.

Section 4: Role of Carbon-based Nanomaterials in Biomedicine

This section predominantly focuses on the utilization of diverse carbon-based nanomaterials in biomedical applications. The different biomedical interfaces range from targeted drug delivery roles of carbon nanomaterials to theranostic applications and bioimaging potentialities of functionalized carbon nanomaterials.

Section 5: Carbon Nanomaterials–based Biosensors/Devices for Food, Agriculture, and Biomedicines

This section mostly looks at different surveys and reviews of the effects of different carbon nanomaterials on biosensors and integrated devices for detecting toxins and food elements in the food sciences and agricultural fields. This section would enable the reader to understand the significance of different carbon-based nanomaterials in the utilization of detection in trace elements in biomedical sciences and in agricultural products.

Section 6: Toxicity Assessment of Different Forms of Carbon-based Nanomaterials (Safety, Health Evaluation [SHE])

This section covers the different aspects of safety and ethical issues pertaining to the design and conductance of clinical trials in the biomedical and agricultural fields. The risks and toxicity aspects of the utilization of diverse carbon-based nanomaterials in the areas of biomedicine and agriculture have been thoroughly discussed.

Upon reading through this book, readers will have gained a comprehensive understanding of the significance of carbon-based nanomaterials as a unique class of biocompatible nanomaterials that has been developed to address various challenges in fields of diverse biosystems and their interactions at the lower dimensions. This book discusses the potential applications of a diverse family of carbon-based nanomaterials in various biological fields in the lower dimensions, with a focus on the interface of nano-biological sciences. This book aims to present the various benefits of incorporating different types of carbon-based nanomaterials in the myriad biosystem domains. Through this introduction, readers will gain a better understanding of the potential advantages of nanobiotechnology and its different applications. The present study also aims to conduct a biotoxicity assessment of different forms of carbon nanomaterials with a focus on safety and health evaluation (SHE) aspects. The study aims to broadly encompass the diverse aspects of carbon nanomaterials in the interplay of different biosystem interface interactions. Such interface study in a broader manner, covering diverse carbon nanostructures of different shapes and properties with different natures of biosystems such as food elements, biomedicines, and agricultural products, would enable the reader to understand the significance of the biointerface reactions and exchanges taking place between carbon nanostructures and myriad bioelements at the lower dimensions, which would help the reader to develop the broader concept of involving different carbon nanostructures in designing and proposing futuristic carbon-based compounds in diverse domains.

Part 1

Carbon-based nanomaterials: fabrication, manufacture, and underlying physicochemical properties

Outline

Chapter 1 Introduction to the carbon-based nanomaterials and its unique electrochemical and physicochemical properties

Chapter 2 Synthesis, characterization, and applications of carbon nanomaterials from a nanobiotechnological perspective

Chapter 3 Green carbon nanomaterials and their application in food, agriculture, and biomedicine

Chapter 4 Recent trends in the bottom-up and top down techniques in the synthesis and fabrication of myriad carbonaceous nanomaterials

Chapter 1

Introduction to the carbon-based nanomaterials and its unique electrochemical and physicochemical properties

M. Boopalan¹, C. Revathi Ganesh² and Sasikumar Arumugam³,    ¹Department of Chemistry, Pachaiyappa’s College for Men, Kancheepuram, Tamil Nadu, India,    ²Department of Chemistry, Chellammal Women’s College of the Pachaiyappa’s Trust, Chennai, Tamil Nadu, India,    ³Electronics and Computer Science, Zepler Building, University of Southampton, Southampton, United Kingdom

Abstract

Carbon nonmaterial shows evidence of incomparable properties and broad possibility of applications. Graphene, fullerene, and carbon nanotubes (CNTs) are the most accepted allotropes of carbon due to their outstanding performance and nontoxic nature compared to other classical materials. Since their discovery, fullerene, CNTs, and graphene, collectively known as carbon-based nanomaterials (CBNs), have garnered much attention. Today, these CBNs are significant in both nanoscience and nanotechnology. Due to their unique characteristics, CBNs are widely used in various sectors, including material science, energy, the environment, biology, medicine, and more. The large surface area, high electrical conductivity, electron mobility, and not expensive availability make these materials a building block for superconducting material studies. This chapter compares the physical, chemical, and physiochemical properties of graphene, fullerene, CNTs, quantum dots, and nanotubes with various dimensionalities.

Keywords

Carbon nanotube; physiochemical properties; electrochemical properties; carbon dots

1.1 Introduction

There are over 100 factors in the periodic table. Of all these elements, carbon has the most diversifying chemistry. This single thing is the middle of a complete department of chemistry natural chemistry. However, carbon science is no longer restricted to solely natural molecules; instead, an extensive spectrum of scientists cheer on this element. Carbon is a chemical component with atomic variety 6 and has six electrons that occupy 1s², 2s², and 2p² atomic orbital. The comprehensiveness of carbon is due to its flexibility toward adopting extraordinary hybridizations (sp, sp2, and sp3) due to the fact of the low power difference between 2S and 2P orbitals. It additionally possesses a valency of four, permitting it to structure single, double, and triple bonds among itself or different elements. These residences are appreciably distinctive in the nanoscale, where every allotrope possesses unique characteristics. Hybridization variability is the cause for the existence of several allotropes of carbon, everyone with one-of-a-kind houses and applications. The allotropes have extraordinary crystal buildings that decide their physicochemical properties. For example, a diamond has a 3D tetrahedral community of sp3-hybridized carbon atoms, whereas graphite is a stacked sheet of hexagonal sp2-hybridized carbon atoms. Breaking down the macroscopic buildings of carbon into nanoscopic buildings explores the most charming world of it [1]. Ironically, this nanoworld of carbon is as big as the universe and has been consistently lovely to scientists due to its discovery. Exfoliating one layer of carbon sheet from graphite creates a new cloth with thrilling houses of graphene, which is the foundation of the entire carbon nanomaterials (CNMs). Graphene, a single layer of carbon atoms arranged in a two-dimensional honeycomb lattice, can be rolled up into carbon nanotubes (CNTs) or wrapped into fullerenes. These two forms of carbon nanomaterials have unique properties and various applications [2].

These carbon nanomaterials have unique physical, chemical, electronic, and mechanical houses and are the concern of intensive, cutting-edge research. For instance, CNTs have sizeable mechanical strength, withstand intense strain, and are one of the most long-lasting substances known. Also, CNTs have thrilling electrical properties, such as substantial electrical conductivity. Graphene is a remarkable material that has garnered significant attention in scientific research and technological development. It is a single layer of carbon atoms arranged in a hexagonal lattice, forming a two-dimensional sheet. Graphene possesses numerous exceptional properties that make it attractive for various applications. While graphene holds tremendous potential, there are still challenges regarding large-scale production, cost-effectiveness, and integration into existing technologies. However, ongoing research and development efforts continue to explore ways to harness the exceptional properties of graphene and unlock its full potential for diverse applications across industries. It has a more significant floor location of all substances, which means that it has a tremendous fraction of uncovered floor atoms [3]. The electron mobility of graphene is as excessive as 2 × 10⁵ cm²/V/s even at room temperature. Discoveries of very regular nanometer measurement sp2 carbon bonded substances such as graphene, fullerenes, and CNTs have influenced inquiries in this field. Graphene, a single layer of carbon atoms arranged in a two-dimensional honeycomb lattice, has garnered significant attention in the scientific community due to its remarkable properties. Let us explore some of the key features that make graphene such a promising material: exceptional mechanical strength: Graphene is incredibly strong, even though it is only one atom thick. It has an intrinsic tensile strength over 100 times greater than steel, making it one of the most robust materials. This property enables its use in applications where high mechanical strength is required. Superior electrical conductivity: Graphene exhibits extraordinary electrical conductivity, surpassing traditional conductors like copper. Electrons can move through graphene with minimal scattering, allowing for ultrafast electron mobility. This property makes graphene an excellent candidate for electronic devices and high-speed circuits.

High thermal conductivity: Graphene possesses exceptional thermal conductivity, enabling it to dissipate heat efficiently. This property is advantageous for applications that require efficient heat management, such as electronics, thermal interfaces, and heat sinks. Flexibility: Graphene is not only strong but also flexible. It can be stretched and bent without losing its electronic properties. This attribute benefits applications requiring flexibility, such as flexible electronics, wearable devices, and sensors. Transparency: Despite being an excellent conductor, graphene is nearly transparent. It absorbs only a small fraction of light across the visible spectrum. This property suits transparent electrodes in displays, solar cells, and touchscreens. Chemical stability: Graphene is chemically stable and impermeable to most gases and liquids. It is highly corrosion-resistant and can withstand a wide range of chemical environments. This stability enhances its potential in applications requiring resistance to harsh conditions. Large surface area: Graphene’s two-dimensional structure produces a high surface-to-volume ratio. This characteristic is advantageous for applications such as energy storage, catalysis, and sensors, as it provides a larger area for interactions with other substances. Due to these exceptional properties, graphene has the potential to revolutionize various industries. Some potential applications include electronics (transistors and flexible displays), energy storage (batteries and supercapacitors), composites (strengthening materials), sensors (chemical and biological), water purification, and many more. However, it is important to note that while graphene holds immense promise, its large-scale production, integration into existing technologies, and cost-effectiveness are still subjects of ongoing research and development. Nonetheless, researchers and engineers are exploring ways to harness graphene’s potential and unlock its widespread applications shortly [4,5].

Due to their special bodily and chemical features, these nanoparticles are increasingly employed to amplify analytical overall performance and simplify the detection system. They are used as labels for sign creation, transduction, and amplification or as carriers for immobilizing biorecognition elements [6]. Nanotechnology can decide disorder biomarkers such as most cancer cells, enzymes, nucleic acids, viruses, and proteins. Biosensors are extensively employed for various purposes such as monitoring glucose in people with diabetes, monitoring exclusive pollution in wastewater to realize hazardous materials, and molecular imaging. 0D, 1D, and 2D carbon-based nanomaterials (CBNs), in conjunction with metallic nanoparticles (NPs), enzymes, polymers, DNA, and ionic beverages, provide various biosensor choices. Nanodiamonds, 1D nanotubes, and 2D graphene nanosheets can all be used as prototypes for nanocomposites. Different NP varieties encompass tubes, horns, spheres, and ellipsoids [7]. CNTs, graphene, rGO, carbon nanodiamonds (CNDs), and carbon dots (CDs) have been the quintessential allotropic changes of nanoscale carbon materials. Carbon nanomaterials provide various technical uses for displaying multiplied overall performance in nanoelectronics, gasoline sensors, textiles, composites, conductive polymers, batteries, and paints. The advantages such as effortless fabrication, catalyst dispersion, reproducibility, stability, and small ohmic resistance are blessings of carbon—primarily based substances as a working electrode. Due to special houses of 2D graphene (GNR), graphene, and its by-products, single-walled CNTs (SWCNTs) and multi-walled CNT (MWCNTs) are the selections to create new foundations for biosensor applications [8].

1.2 Carbon-based nanomaterials

1.2.1 Carbon nanotube

CNTs are cylindrical structures of carbon atoms arranged in a hexagonal lattice. They have remarkable properties that make them attractive for a wide range of applications in various fields of science and technology (Fig. 1.1).

Figure 1.1 Carbon nanotube.

Here are some key features and characteristics of CNTs:

Structure: CNTs can be considered rolled-up sheets of graphene, where each carbon atom is bonded to three neighboring carbon atoms. The arrangement of these bonds gives rise to the cylindrical structure, with the tube diameter typically on the nanometer scale.

Types of CNTs: CNTs can be categorized into two main types based on their structure: single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs). SWNTs consist of a single cylindrical wall, whereas MWNTs have multiple concentric walls, like a Russian nesting doll.

Exceptional mechanical strength: CNTs possess exceptional mechanical properties. They are extreme and stiff, with tensile strengths several times greater than steel. They also exhibit high elasticity, allowing them to deform under stress and return to their original shape.

Electrical conductivity: CNTs exhibit excellent electrical conductivity, especially for SWNTs. They can carry a high electrical current density without significant resistance, making them attractive for applications in electronics, conductive films, and energy storage devices.

Thermal conductivity: CNTs have high thermal conductivity, surpassing most materials. This property makes them valuable in thermal management applications, such as heat sinks, thermoelectric devices, and thermal interface materials.

Nanoscale Dimensions: CNTs have unique nanoscale dimensions and exceptional properties. Their high aspect ratio (length-to-diameter ratio) enables their integration into nanoscale devices and composite materials, imparting their properties at the macroscale.

Applications: CNTs have a wide range of potential applications. They can be used in electronics for transistors, interconnects, and sensors. Their mechanical strength makes them useful in composite materials, such as sports equipment and lightweight structural materials. They also promise in energy storage, water purification, biomedical devices, and many other fields.

It is worth noting that while CNTs hold great potential, their large-scale production and integration into commercial applications still face challenges, particularly in terms of cost, scalability, and controlled synthesis. Nonetheless, ongoing research and development continue to explore their vast possibilities [9–13].

1.2.2 Graphene

Among the new generations of carbon-based total nanomaterials, graphene (GR) (Fig. 1.2) is undoubtedly the most developed and engineered in many fields of applications [14]. This carbon allotrope structure is like a hexagonal honeycomb lattice and can be viewed as the founder of many different allotropes of carbon, such as graphite and CNTs. GR is the thinnest compound regarded at one atom thick, the lightest cloth acknowledged (with 1 rectangular m coming in at around 0.77 mg), the most vital compound determined (between 100 and 300 instances superior to metal and with a tensile stiffness of 150,000,000 psi), the great conductor of warmth at room temperature (around 5000 W/mK) and additionally the great conductor of electrical energy recognized (with stated service mobility of greater than 15,000 cm²/V/s) [15].

Figure 1.2 Structure of graphene.

The outstanding electrical and chemical homes of GR blended with its biocompatibility, furnish possibilities for new biomedical applications. Its easy molecular structure and GR potential to mix with different current nano- and biomaterials make it appropriate for a range of functions, and it has been developed in an extensive range of GR-based materials. Single-layer graphene, bilayer graphene, multilayer graphene, graphene oxide (GO), decreased graphene oxide (rGO), and chemically modified GR are the participants of the GR-based nanomaterial family: every member of this household possesses its aspects in phrases of oxygen content, range of layers, floor chemistry, purity, lateral dimensions, defect density and composition [16]. Due to its reactive surface, single-layer defect-free GR manufacturing is complex, and it is also challenging to droop in water solutions. These are the predominant motives why GO and rGO are commonly favored for organic applications.

1.2.3 Fullerene

The first fullerene C⁶⁰ got here to lifestyles in 1985; however, the household of fullerenes consists of a wide variety of carbon-based molecules with distinct quantities of carbon atoms and symmetries. The most frequent fullerene is additionally known as buckyball and consists of 60 carbon atoms organized into 12 pentagons and 20 hexagons to create a shape with the geometry of a hole sphere [17]. C⁶⁰ attracted high-quality interest due to its very secure and symmetric structure (Fig. 1.3). Fullerenes are considered zero-dimensional materials, which possess fascinating bodily and chemical homes for remedy and technology. The essential problem of C⁶⁰ in the biomedical subject is represented through its herbal water repulsion and ensuing hydrophobicity. This insolubility in aqueous media induces fullerenes to mixture, pushing the lookup to boost several techniques to overcome the problem [18].

Figure 1.3 Fullerene.

Hydroxyl and malonic acid functionalized fullerenes discovered essential functions in neuroprotection toward free radicals generated through fatty acid cardiometabolism, which neurons are prosperous of after talent harm or inflammatory response to diseases. These fullerene derivatives can interrupt chain reactions, producing the radicals by doing away with intermediate peroxyl radicals and displaying sturdy neuroprotection endeavors in 438.

Fullerenes, another form of CBNs, have been extensively studied and explored for various applications, including biomedical applications. Some areas are where fullerenes have been considered organic photovoltaics, fuel storage, and molecular sensing. In the past 30 years, fullerenes have gained significant attention for their potential biomedical applications. Some proposed biomedical uses of fullerenes include oxidative damage protection, photosensitizers for photodynamic therapy, antiretroviral agents, and drug and gene delivery vectors. These biomedical applications of fullerenes are still in the research and development stage, with ongoing studies and investigations to understand their efficacy, safety, and potential clinical applications. While there are promising results, further research is needed to explore and harness the potential of fullerenes in these areas. [19,20].

1.3 Dimensionality

Nanomaterials are materials engineered at the nanoscale, typically ranging from 1 to 100 nm in size. At this scale, materials exhibit unique properties and behaviors that differ from their bulk counterparts (Fig. 1.4).

Figure 1.4 The dimension of nanomaterials.

1.3.1 Zero dimension

Zero-dimensional (0D) nanomaterials, or quantum dots, are tiny semiconductor particles that exhibit unique properties due to their extremely small size and quantum confinement effects. Quantum dots can be synthesized from various materials such as cadmium selenide, lead sulfide, or indium arsenide, and typically have dimensions of 1–10 nm. Fullerenes have attainable software in remedy as they can be used as transport for drug launch because they have appropriate biocompatibility, selectively hold organic recreation, and their measurement is small sufficient to be diffused. Carbon quantum dots are a type of carbon-based semiconductor nanomaterial that has gained significant attention recently. They are being studied as potential alternatives to traditional semiconductor quantum dots due to several advantages, including fluorescence properties, biocompatibility, and lower toxicity for their use in biological applications, as they minimize potential adverse effects on cells and tissues [21].

Dimensions in xyz are <100 nm.

1.3.1.1 One dimension

Nanobars and nanowires refer to structures with a bar-like or wire-like shape, respectively, in the nanoscale. They can be made from various materials, including metals, semiconductors, or carbon. Nanobars and nanowires are utilized in nanoelectronics, sensing applications, and as building blocks for nanoscale devices. Nanoribbons are thin, elongated structures with a width in the nanometer range. They can be fabricated from various materials, such as graphene or semiconducting materials like silicon. Nanoribbons exhibit unique electronic properties and have potential applications in nanoelectronics, optoelectronics, and quantum devices. Their nanoscale dimensions often result in enhanced properties or enable novel functionalities, contributing to advancements in various technological areas [22].

Dimension in XYZ is < 100 nm.

1.3.1.2 Two dimensions

2D nanomaterials, which are sheet-shaped materials with one dimension in the nanoscale. Graphene’s unique properties and versatility make it a material of great interest in various fields, including medicine, energy, electronics, and filtration. Ongoing research and development efforts aim to explore further and harness its potential for practical applications such as medicine GOs, and energy and make it a potential candidate for advanced electronics such as touchscreens, transistors, etc.

Dimension in one direction is <100 nm.

1.3.1.3 Three dimensions

Some examples of such materials are graphite, polycrystals, diamonds, GOs, and aerogels. These materials demonstrate the diverse range of three-dimensional nanostructured materials, nanoparticle dispersions, and multi-nanolayers. Each material offers unique properties and applications, contributing to various scientific and technological advancements [23].

Dimensions in XYZ are >100 nm.

1.3.2 Size and surface area of the particles

Highlighting the importance of particle size and surface area in the interaction of nanomaterials with biological systems. Reducing the size of particles leads to an exponential increase in their surface area relative to their volume. This increased surface area makes nanomaterials more reactive and can affect their interaction with the surrounding environment. Particle size and surface area also play a role in how the biological system processes, distributes, and eliminates the materials. Various biological mechanisms, such as endocytosis and cellular uptake, are influenced by the size of nanomaterials. The efficiency of particle processing in the endocytic pathway and cellular uptake can depend on the size of the particles. In vitro studies have been conducted to evaluate the cytotoxicity of nanoparticles of different sizes, but in vivo assessment is more challenging due to the complex nature of biological systems. Nanoparticles can exhibit toxicity in vivo through mechanisms such as the generation of oxidative responses and the formation of free radicals. Smaller nanoparticles have been shown to have a greater potential for forming reactive oxygen species, which can cause damage to DNA, and lipids, and induce inflammatory responses. The surface area is also important in manifesting toxic effects, particularly in inducing lung and epithelial inflammatory responses in animal models. Understanding the effects of particle size and surface area is crucial for assessing the toxicity and pharmacological behavior of nanomaterials in biological systems. Further research and comprehensive studies are needed to understand better the specific interactions and potential risks associated with different nanomaterial sizes and surface characteristics [24–26].

1.3.2.1 Effect of particle shape and aspect ratio

Indeed, the shape of nanomaterials plays an important part in their toxicity and biological interactions. Nanoparticles of different shapes, such as fibers, rings, tubes, spheres, and planes, have been studied for their potential toxicity. The shape of nanoparticles can influence their interactions with biological membranes during endocytosis or phagocytosis. It has been observed that spherical nanoparticles are easier and faster to take up compared to rod-shaped or fiber-like nanoparticles. Spherical nanoparticles also tend to be less toxic, regardless of their homogeneity or heterogeneity. Nonspherical nanoparticles may have different biological effects, including their ability to flow through capillaries. Various nanoparticles have shown shape-dependent toxicity. For instance, rod-shaped SWCNTs have been found to block ion channels more effectively than spherical carbon fullerenes. The shape-based toxicity of silica allotropes is evident, where amorphous silica is used as a food additive while crystalline silica is considered a suspected human carcinogen. Gold nanorods have slower uptake than spherical nanospheres, and their uptake reaches a maximum when the aspect ratio approaches unity. TiO2 fibers are more cytotoxic than spherical entities, and the toxicity increases with higher aspect ratios.

Fibrous nanomaterials, such as asbestos fibers and CNTs, exhibit length-dependent toxicity. Longer fibers are less effectively cleared from the respiratory tract, increasing health risks. Asbestos fibers longer than 10 µm have been associated with lung carcinoma, while fibers longer than 5 µm can cause mesothelioma, and fibers longer than 2 µm can lead to asbestosis. TiO2 fibers with a length of 15 mm are highly toxic and induce an inflammatory response in mice. Longer aspect ratio particles, such as long SWCNTs, have demonstrated significant pulmonary toxicity compared to spherical particles. The solubility of fibers in lung fluid is an important factor in their toxicity. Soluble fibers can disappear within months, while insoluble fibers may remain in the lungs indefinitely. The longer aspect ratio and insolubility of fibers contribute to their persistence and potential toxicity. Understanding the shape-based toxicity of nanomaterials is crucial for the safe implementation of nanotechnology-based systems. Further research and investigation of these phenomena will contribute to the development of safer nanomaterials and nanotechnology applications [27–29].

1.3.3 Number of layers

1.3.3.1 Graphene

The number of layers in graphene can range from a few layers to many layers, depending on how the material is produced and manipulated. Researchers have synthesized graphene with various layer numbers, including bilayer graphene (two layers), trilayer graphene (three layers), and so on. In principle, it is possible to stack many graphene layers to create a bulk-like material, but it would lose some of the unique properties of monolayer graphene.

It is worth noting that the term graphene is often used to refer to both monolayer graphene and few-layer graphene, depending on the context. These composites exhibit improved fracture toughness, fatigue life, and electrical properties. Graphene can also be combined with other nanomaterials, such as precious metals or metal compounds, to create composites with enhanced optical, mechanical, electrical, chemical, sensing, and catalytic properties.

In photovoltaics, optoelectronics, and photodetection, graphene is studied for its potential use in devices, particularly in combination with polymers. Graphene can be used in perovskite solar cells, as anodes in solar cells, and for electromagnetic interference (EMI) shielding in composite structures. The challenge in using graphene and graphene-based materials in composites lies in their solubility and liquid dispersibility. Additionally, graphene can be a starting point for forming other carbon allotropes, such as fullerenes and CNTs. Overall, graphene’s unique properties make it a promising material for a wide range of applications, and ongoing research aims to overcome challenges and further explore its potential in various fields [30–32].

1.3.3.2 Fullerenes

Fullerenes are a family of carbon molecules composed of carbon atoms arranged in closed cages or spheres. The most well-known and studied fullerene is buckminsterfullerene, also known as C⁶⁰, which resembles a soccer ball with 60 carbon atoms arranged in a structure of 20 hexagons and 12 pentagons. This particular fullerene was named after Buckminster Fuller, an architect who designed geodesic domes similar in shape to C⁶⁰.

Fullerenes were first discovered in 1985 by a team of scientists led by Sir Harold Kroto, Robert Curl, and Richard Smalley. They were conducting experiments related to interstellar matter and carbon-rich environments. The discovery of fullerenes earned them the Nobel Prize in Chemistry in 1996.

Fullerenes can be found naturally in small quantities, such as in certain minerals, soot, and cosmic dust. However, they can also be synthesized in the laboratory using various methods.

The most common technique involves vaporizing graphite in an inert gas atmosphere, forming fullerenes.

Fullerenes exhibit unique physical and chemical properties due to their hollow cage-like structure. They are known for their high tensile strength, low reactivity, and excellent electron-accepting and donating capabilities. These properties make fullerenes useful in a wide range of applications, including:

Material science: Fullerenes can be used to enhance the properties of materials, such as polymers and composites. They can improve mechanical strength, thermal stability, and electrical conductivity.

Electronics: Fullerenes have been explored for their potential in electronic devices, such as transistors and solar cells. They can act as electron acceptors or donors in organic semiconductors.

Medicine: Fullerenes have shown promise in medical applications. They can be functionalized with various molecules to deliver drugs or imaging agents to specific targets in the body. They also exhibit antioxidant properties and have been studied for their potential to fight free radicals.

Energy storage: Fullerenes have been investigated for their use in energy storage devices, such as batteries and supercapacitors. They can enhance the capacity and performance of these devices.

Nanotechnology: Fullerenes are used as building blocks in nanotechnology. They can be combined with other molecules to create new materials with tailored properties. Research on fullerenes and their applications is ongoing, and scientists continue to explore their potential in various fields [33,34].

1.3.3.3 Carbon nanotubes and nanofibers

CNTs are cylindrical structures made of carbon atoms arranged in a hexagonal lattice. They have unique properties and are considered one of the most promising materials for various applications, including electronics, materials science, energy storage, and biomedical engineering. Carbon nanofibers (CNFs) are cylindrical nanostructures composed primarily of carbon atoms. They are considered a type of nanomaterial and have gained significant attention in various fields due to their unique properties. CNFs are extremely thin, with diameters on the order of a few nanometers, and can have lengths ranging from micrometers to centimeters.

The structure of carbon nanofibers can vary, but they generally consist of stacked graphene layers arranged in a coaxial or turbostratic configuration. This arrangement gives CNFs their high aspect ratio, with a large surface area relative to their volume.

To achieve dispersion and improve interfacial interaction with the polymer matrix, techniques such as sonication, the addition of surfactants, and surface functionalization of CNTs can be employed. Surface functionalization can be achieved through chemical processes or plasma treatment, introducing functional groups that enhance dispersion and compatibility with the surrounding matrix. Overall, CNTs, CNFs, and carbon fibers have diverse applications and offer unique properties that make them valuable for use in composites and various industries. The challenge lies in achieving proper dispersion, interfacial interaction, and homogeneous distribution of carbon nanoparticles within the matrix to fully utilize their potential CNF, which possess excellent mechanical, electrical, and thermal properties, making them attractive for various applications. Some of their notable properties include:

Mechanical strength: CNFs exhibit high tensile strength and stiffness, making them suitable for composite materials reinforcement. They can improve the mechanical properties of polymers and metals when incorporated into composites.

Electrical conductivity: CNFs have good electrical conductivity, allowing them to be used in applications requiring conductivity, such as electrodes for batteries, supercapacitors, and fuel cells.

Thermal conductivity: CNFs have high thermal conductivity, making them useful in applications requiring efficient heat dissipation, such as thermal interface materials and heat sinks.

Chemical stability: CNFs are chemically stable and can withstand harsh environments, making them suitable for applications in corrosive or reactive conditions.

Lightweight: Due to their nanoscale dimensions, CNFs are lightweight, which is advantageous for applications that demand lightweight materials, such as aerospace components.

Applications of CNFs span across various industries and fields. Some examples include the following:

Aerospace and defense: CNFs can be used in lightweight structural components, thermal management systems, electromagnetic shielding, and energy storage devices.

Energy storage: CNFs are utilized in electrodes for lithium-ion batteries, supercapacitors, and fuel cells due to their high surface area and electrical conductivity.

Composite materials: CNFs are incorporated into polymers, metals, and ceramics to enhance mechanical properties, such as strength, stiffness, and impact resistance.

Electronics and conductive materials: CNFs find applications in conductive inks, printed circuit boards, sensors, EMI shielding, and nanoelectronics.

Environmental applications: CNFs are explored for water purification, air filtration, and as catalyst supports in environmental remediation processes. It is important to note that the production and manipulation of CNFs require specialized manufacturing techniques and expertise due to their nanoscale nature. Safety considerations and proper handling procedures are crucial to ensure the well-being of researchers and users working with CNFs [35–38].

1.3.4 Surface functionalization

Covalent and noncovalent functionalization: Both covalent and noncovalent functionalization methods have their advantages and disadvantages, and the choice of functionalization approach depends on the specific requirements and applications. Covalent functionalization generally provides stronger interfacial interactions but may introduce defects or alter the intrinsic properties of the nanomaterials. Noncovalent functionalization offers greater flexibility but may result in weaker interfacial interactions.

1.3.4.1 Covalent functionalization approach

In covalent functionalization, functional groups or molecules form covalent linkages with the carbon framework of the graphene or CNTs [39].

1.3.4.1.1 Covalent functionalization on the usage of click chemistry

Due to the sturdy interlayer cohesive strength and the floor inertia of graphene, it stays mission to enhance powerful and reliable techniques to functionalize graphene covalently. Carbon nanomaterials (graphene/CNTs) functionalization needs to be precisely controlled for sensible applications. Therefore there is an actual want for unique chemical reactions that permit the amendment of CNMs in an easy way. Cycloaddition reactions are raising an enormous route. Cycloaddition reactions usually proceed between two unsaturated entities to provide a cyclic product in an atom-economic manner, the place the float of electrons takes vicinity from the easiest occupied molecular orbital (HOMO) of one molecule to the lowest unoccupied molecular orbital of the different molecule. The functionalization of CNMs with the aid of the potential of cycloaddition reactions performs a necessary function in this regard. It covers a huge range of reactions, together with the 1,3-dipolar cycloaddition of azomethine ylides, CuI-catalyzed azide-alkyne cycloaddition reactions, [4+2] Diels–Alder reactions, [2+1] cycloaddition reactions, and different cycloaddition reactions. The existing part focuses on the covalent functionalization of CNMs using copper-catalyzed azide-alkyne click response (a version of Huisgen 1,3-dipolar cycloaddition response between terminal azides and acetylenes). Through this reaction, a considerable range of molecules can be coupled onto CNMs in a very managed manner. It should be utilized for many attainable purposes, from nanoelectronics to bioapplications [40].

1.3.4.1.2 Noncovalent and different functionalization approaches

The downside of covalent functionalization is that the best shape of CNTs or graphene is destroyed, resulting in huge modifications in their bodily properties. In noncovalent functionalization, hydrogen bonding (H-bonding) and π–π stacking interactions play a crucial role. These interactions can enhance the solubility of CNTs and graphene and facilitate their assembly without significantly affecting the π–π conjugation of the nanomaterials’ carbon skeleton. A water-soluble pyrene by-product was once used to secure aqueous dispersions of graphene sheets, given that the pyrene moiety has a sturdy affinity for the graphite thanks to π–π stacking. Long-range self-assembled graphene monolayers have been produced using π–π interactions for various applications. Very recently, quite a few graphene has been noncovalently functionalized with polymers utilizing a couple of π–π stacking, H-bonding, and hydrophobic interactions. A straightforward water-answer processing approach used to be used for the instruction of poly(vinyl alcohol) nanocomposites with graphene oxide, resulting in an enlargement in their mechanical properties. The dramatic amplification of mechanical homes has been attributed to the sturdy noncovalent interplay through H-bonding.

On the other hand, noncovalently Nafion-functionalized obvious conducting motion pictures of graphene have been fabricated through the discount of a GO/Nafion dispersant and hydrazine usage. These movies have been produced through the hydrophobic interplay of Nafion with a graphene floor primary to the exfoliation of the graphene with the aid of an electrosteric mechanism. Stable dispersion of decreased graphene in various natural solvents has additionally been performed with noncovalent functionalization with amine-terminated polystyrene polymers by sonication. Electrochemically practical graphene nanocomposites have been organized through the one-step liquid-phase exfoliation of herbal flake graphite with methylene blue. Atomic pressure microscopy and Raman spectroscopy established that the graphene used to be exfoliated into single-layer or bilayer states. Fourier seriously changes infrared (Fourier-transform infrared spectroscopy) spectroscopy suggests that π–π stacking interplay was once concerned with the structure-associated interactions between graphene and adsorbed methylene blue molecules. Kim et al. have developed hydrophilic-to-hydrophobic segment transferable graphene sheets using ionic liquid polymers, poly(1-vinyl-3-ethylimidazolium) [41].

1.4 Physical properties of carbon nanomaterials

1.4.1 Electrical

The conductivity of bulk materials, such as metals, is not significantly influenced by parameters like diameter, location of the current path, or twist in the conducting wire. CNTs can act as conductors or semiconductors depending on their structure and the arrangement of carbon atoms. Metallic CNTs, which have a certain arrangement of carbon atoms, behave as conductors and exhibit high electrical conductivity. On the other hand, semiconducting CNTs have a different arrangement and display varying levels of electrical conductivity depending on their bandgap. Also, the electrical conductivity of CNTs and CNT-based materials can be influenced by defects, mechanical strain, and the collective behavior of nanotubes within ensembles.

1.4.2 Thermal

Graphene and CNTs can beautify the thermal homes of polymer composites due to their excessive thermal conductivity, thermal stability, and geometrical effect on the thermal interface resistance. Recently, many researchers have investigated the thermal conductivity and thermal balance of polymer composites based totally on graphene and CNTs. The thermal conductivity of the polymer composites is affected by the structural fine of carbon nanomaterials in the polymer matrix, filler loading, filler dispersion, and the thermal resistance of the interface between the nanofillers and the polymer matrix. For example, the thermal conductivity of a multi-graphene platelet (MGP)/epoxy polymer composite containing 1 wt.% graphene used to be better via 23.8%, whereas the thermal conductivity of a pristine. MWCNT/epoxy composite used to be improved via 62% at an equal CNT loading. Aggregated MGPs have a decreased issue ratio, reducing the contact place between MGPs and the epoxy matrix and causing phonon scattering. However, introducing each filler into the epoxy matrix yielded P-MWCNT/MGP/epoxy composites and substantially accelerated the conductivity (93%) compared to epoxy composites with character fillers. The lengthy and tortuous MWCNTs bridge the adjoining MGPs, inhibiting their aggregation and enhancing the MGP contact with the polymer matrix [42,43].

1.4.3 Mechanical

Theoretical prediction of the mechanical residences of CNTs was, to our knowledge, first by the usage of a Keating potential. The authors have proven that Young’s modulus of small SWCNTs can be up to 1.5 TPa, which surpasses substances normal for an excessive tensile strength, such as metal strings, artificial fibers, and so forth. Other agencies have used extraordinary empirical and nonempirical techniques, large fashions, and more than one layer to predict more than a few mechanical houses of CNTs, which additionally exhibits that CNTs are certainly anticipated to be resilient materials. Experimentally, the mechanical residences of CNTs were decided by staring at the vibrations of CNTs with a transmission electron microscope. Measuring the amplitude of vibrating multi-walled CNTs has shown that Young’s modulus value is 1.8 TPa. The atomic pressure microscope tip with anchored MWCNTs to measure the bending pressure of the CNTs received a standard cost of 1.28 TPa. Other experiments have proven comparable or worse effects, relying on the pattern and the experimental conditions. The purpose for these deviations in the observed values is the experimental approach itself and the nature of CNTs. Since CNTs are nanosized materials, manipulating and measuring their mechanical properties is extraordinarily tough. This makes it tough to reproduce the identical experimental stipulations for mechanical testing. Even in the identical batch of synthesized CNTs, a length, layer number, diameter, and crystallinity distribution are observed. Significantly, the crystallinity of the tube wall appreciably impacts the mechanical residences of CNTs. Therefore deciding on specific kinds of CNTs also impacts the experimental values, affecting the giant discrepancy among the mentioned values. From the extensive distribution of Young’s moduli in various measurements, we can recognize the threshold values, which can supply an indication of what we can also anticipate from the CNT as soon as it is utilized in CNT composite materials [44–46].

1.4.4 Electronic and optical

Various studies and reviews are related to carbon nanomaterials, including 0D materials such as graphene quantum dots (GQDs), nitrogen-rich carbon dots (N-CDs), and 1D and 2D carbon nanomaterials.

Synthesis of GQDs from waste products: GQDs with excellent optical properties were synthesized from antibiotics and ethylenediamine through a thermal procedure in an autoclave. This approach offers a sustainable method for producing GQDs. N-CDs were synthesized through the thermally induced decomposition of organic precursors. These N-CDs exhibited a core–shell structure with a beta-C3N4 crystalline structure in the core and various polar functional groups on the surface. The presence of charged surface groups contributed to the colloidal stability of N-CD dispersions. Careful analysis of contaminations is crucial to accurately attribute the optical features of CDs and avoid misleading results. The proliferation of carbon-deficient or carbon-less CDs in the literature was discussed, highlighting the importance of addressing this issue. The interaction between CDs and halogen ions of different atomic numbers was studied. Negatively charged ions were found to cause emission quenching, primarily through static quenching via binding to suitable surface sites on the CDs.

First-principles studies were conducted to investigate the optical and chemical properties of beta-C3N4 structures at different dimensionalities, from bulk to nanoclusters. The electronic and optical properties were found to be influenced by surface states and exhibited bandgap modifications. Fluorescence emission and models of carbonaceous nanoparticles: The origin of fluorescence emission in carbonaceous nanoparticles was discussed at a fundamental level. A model based on resonance electronic interactions among the chromophore elements within the nanoparticles was proposed to interpret the optical response of CDs.

The properties of 1D linear carbon chains produced through carbon plasma ion-stimulated condensation were studied theoretically and experimentally. The work function of the material was found to be influenced by a combination of substrate structure and terminal group type, making it suitable for electronic and sensing applications. 2D carbon nanomaterials, specifically graphene (Gr): Reviews and studies focused on the preparation and growth of single and multilayer graphene. Ethanol vapor as a precursor for graphene synthesis was compared to more standard methods. The electronic and structural properties of single-layer graphene were investigated through spectroscopic techniques, and the potential for thermal doping to engineer graphene properties was highlighted. Gr on SiC was proposed for Hg sensing, and the role of dispersive force interactions and surface sites in sensitivity improvement was discussed. The challenges of growing high-quality dielectrics on epitaxial graphene and chemical vapor deposition (CVD) graphene were addressed. Advances in atomic layer deposition of high-k materials and the role of graphene–substrate interactions were reviewed. The application of GO in electrospun polymeric patches for treating burns and skin conditions was also explored. These studies and reviews contribute to the understanding and potential applications of carbon nanomaterials in various fields, including optoelectronics, sensing, microelectronics, and biomedical applications