Multifaceted Bio-sensing Technology

Multifaceted Bio-sensing Technology introduces the different types of biosensors, their construction materials, configurations, production methods, and their uses in bioelectrochemical fuel cells (BEFC). It focuses on recent progress in the production of biosensing platforms/interfaces, their integration, design and fabrication, and their multifaceted applications in bioelectrochemical systems. The chapters explore the integration of genetic elements such as DNA, enzymes, and whole cells within these systems, and address environmental applications including wastewater contaminant detection, toxicity, and bioremediation. Throughout, the book shows how rapid, minuscule, and affordable biocomponents can be produced for a variety of energy and environmental applications.

This book provides a practical introduction to the production of biocomponents for bioelectrochemical devices and environmental monitoring, and will be a useful reference for graduates and researchers involved in the application of bioelectrochemical systems, as well as those working more broadly in bioenergy, electrochemistry, biology, environmental engineering, and multidisciplinary research across those areas.

• Examines the applications of biosensors in bioelectrochemical fuel cells and other fields and their integration and assembly for future uses
• Explores on the application of carbon nanomaterials in biosensors
• Presents detailed schematics and calculations that outline integrations in bioelectrochemical systems

• Language: English
• Publisher: Academic Press
• Release date: Nov 8, 2022
• ISBN: 9780323998093

Book preview

Chapter 1

Introduction to sensors and types of biosensors

Bidyut Kumar Kundua,b

aSchool of Applied Sciences, Centurion University of Technology and Management, Bhubaneswar, Odisha, India

bDepartment of Chemistry, University of Cincinnati, Cincinnati, OH, United States

1.1 Introduction

Sensor is one such important tool in current times, which are used all around us. From smoke detector to a mobile phone's unlock bottom, we are very fond of using sensors in each step of our life without knowing its background and working principle. By definition, sensor could be a device accustomed sense a physical variable, which includes, however is not restricted to mass, pressure, humidity, strain, electrochemical response, temperature, light, and voltage [1–4]. To sense these variables, the conversion of them are required into a universal and easily accessible signal (e.g., to sense electrochemical response, a bio-electrochemical fuel cell (BEFC) is required) [5], that is, sometimes a voltage [6]. This voltage signal changes endlessly with time, and is directly proportional to the respective physical variable [7]. An element accountable for this translation of energy from one form to another form could be a transducer. Sensors can be categorized into three major classes such as physical sensors, chemical sensors, and biosensors [2,4,8,9].

Among which, biosensor is an analytical device encompassing an immobilized biological substance (hormone, antibody, nucleic acid, enzyme, organelle, or whole cell), which might exactly interact with an analyte and give chemical, electrical, and physical signals for accurate measurement [9–16]. Where, an analyte can be defined as a compound (e.g., DNA/RNA, antigen/antibody, pesticide, drug, urea, glucose, pollutant), which will be measured via determination of concentration [15,17–20]. Biosensor possesses five key components such as receptor, transducer, amplifier, signal processor followed by a display unit. In biosensors, transducer converts the biochemical activity into electrical energy [9,12,21–23].

Fig. 1.1 shows that the variables of interest in biosensors are classically the sort and also the concentration of a particular analyte, which can be a specific protein, a virus particle, a bacterium, a sequence of nucleic acid (ca. RNA or DNA), a simple biochemical compound (ca. glucose), and so forth [16,24,25]. The conventional sensors cannot determine these variables, for example, pressure, strain, temperature, or light transducers. Consequently, we require additional element called as a bioreceptor. This bioreceptor is a biological component or a biomimetic, which comprises tissues, bacteria, viruses, nucleic acids, enzymes, antibodies, etc. In addition, a bioreceptor will precisely bind to a target analyte and root a transducer to make a voltage signal [26–29].

Fig. 1.1 Chart representation of the key components of a biosensor.

The binding method between bioreceptors and target biomolecules is extremely specific such that the employment of an antibody to Escherichia coli (anti-E. coli) as a bioreceptor will produce a voltage indication only if E. coli presents within the sample, however the presence of different viruses or bacteria in the sample will not influence the voltage [14]. Apart from that, nucleic acids (RNA and DNA), and antibodies are the most favored among the bioreceptors [14,27,30–32]. The transducers stated in Fig. 1.1 may be employed for biosensors, with some alterations. The most frequently used transducers for biosensors contain: electrochemical (by evaluating current or voltage), thermal (by quantifying temperature), optical (by calculating light intensity), and piezoelectric (this are going to be mentioned later) [33–37].

Glucose sensor is the most effective commercial biosensor application that has been established till date. The glucose sensor is widely used to monitor the blood glucose content for diabetic patients. It has determined the topical evolution and currently accounts for over 85% of the industrial biosensor market [34,38–41]. Further novel biosensors are now being investigated and established for food/water safety, monitoring of environment, and medical diagnostics [42–44]. Though we have previously contributed on some crucial topic such as metalloenzyme mimetics [45–48], bioinspired catalysis [47–50], and metallodrug applications [14,46,51–58] but this is the first step towards talking on one more important issue, that is, biosensors [9,13,15,16]. Thus, this chapter is specially dedicated towards the description about the biosensors, their classifications, mechanistic action, key features, applications, and scope.

1.2 Classification of sensor

A sensor is a device which can detect events or changes in its environment and then convert it into a compatible signal, which might be easily understood by an instrument or by an observer. Our organs like eye, nose, ears, tongue, and skin are the examples of natural sensors [4,9,59–61]. Artificial or manmade sensors can be divided into three major classes (Scheme 1.1):

• Physical sensors for measuring temperature, distance, mass, pressure, etc.

• Chemical sensors for detecting/estimating different chemicals in solution, solid, liquid, gaseous state.

• Biosensors for detecting/estimating different chemicals by using a biological sensing element.

Scheme 1.1 Flow chart showing the various types of sensors.

In this chapter, only the concept of biosensors will be dealt with. The substance to be recognized/estimated by a biosensor shall be termed as analyte.

They can be broadly classified into electrochemical and optical sensors according to the types of transducers used for detection:

• Electrochemical sensors can be formed by addition of a redox-active group to a receptor. For such a sensor to advantageous, the receptor should be selective for the guest of attention and the binding course must be united to the redox reaction; alternatively, the redox-active center must feel the presence of the bound guest. Many molecular sensors, for example, bipyridinum, quinone, and ferrocene have been united further into redox-active groups [62,63].

• Optical sensors are constructed on the amount of light emitted or absorbed as an effect of a chemical reaction between the analyte and the sensor [64–66]. An important example of this type is the fluorescent sensor, which undergoes a change in its fluorescence emission properties as a consequence of the detection process [67–70]. Fluorescent sensors constitute an influential tool to monitor metal ions and biologically active analytes in vitro and in vivo as their high sensitivity simplicity, and real-time in-situ imaging capability [71–73]. In the past decade, more and more chemosensors, especially fluorescent sensors, have been used to notice various types of inorganic and organic molecules, elbowing their way to center phase in the arena of molecular recognition [62].

1.3 Biosensors

Leland C. Clark Jr. (1918–2005), father of the biosensor is acknowledged as the inventor of the Clark electrode a device or biosensor used for determining oxygen in blood, water, and other liquids. Later on, in 1967, enzyme-based biosensor was first reported by Updike and Hicks. Basically, biosensors constitute yet another frequently used type of sensor. A biosensor is an analytical device, used for the detection as well as quantification of an analyte, which integrates a biological component with a physicochemical detector [12,74]. A biosensor is one in which either the reporter or the analyte is an entity of biological interest. It may incorporate a biological component as a key functional element or detect biomolecules in a quantitative or qualitative way [74–77]. Biosensor devices use definite biochemical reactions facilitated by tissues, immunosystems, isolated enzymes, organelles, or entire cells to perceive chemical compounds usually by thermal, electrical, or optical signals [75,78]. It primarily involves of three fragments:

1. The sensitive biological element, for example, microorganisms, organelles, cell receptors, nucleic acids, enzymes, antibodies, tissue, etc.

2. The transducer or the detector component (may work in different ways: electrochemical, optical, piezoelectric, etc.) that converts the signal coming from the interaction between biological element and the analyte into another signal for the precise measurement and quantification.

3. Accompanied electronics or signal processors that are mainly accountable for the display of the outcomes in a user-friendly mode.

The aim of a biosensor is to generate a digital electronic signal that is proportional to the concentration of a particular chemical or set of chemicals/biochemicals. Biosensor instruments are simple, specific, and rapid to operate and can be smoothly fabricated with slight sample pre-treatment necessitated. The efficacy of a biosensor is determined by the analyte determination step. Biocomponents within a biosensor have a keen level of selectivity nonetheless are susceptible to vigorous circumstances such as ionic strength, pH, and temperature [76,77]. Most biomolecules such as antibodies, receptors, enzymes, cells, etc. have small lifetimes in solution phase. Hence, a suitable matrix is required to fix them. The activity of immobilized molecules depends upon reaction conditions, hydrophilic character of immobilizing matrix, porosity, surface area, and the methodology elected for immobilization.

Numerous matrices have been used for the immobilization of enzymes, such as polymeric films, silica, graphite, carbon, membranes, gels, etc. with the biological constituent and can step to quick electron transfer at the electrode surface.

1.3.1 Working principle of a biosensor

Biosensors are functioned as on the principle of signal transduction. First, bioreceptor is permissible to interact with an analyte of interest. The transducer measures this interaction and generates a signal. The concentration of the analyte is proportional to the intensity of the output followed by amplification of the signal and administered by the electronic process to display a readable value (Fig. 1.2).

Fig. 1.2 Working pathways of a biosensor.

1.3.2 Features of a biosensor

The following points represent the main characteristics of a biosensor. These are:

i. It should be extremely specific for the analyte.

ii. The reaction used should be independent of controllable features like stirring, temperature, and pH etc.

iii. The response should be linear over a useful range of analyte concentrations.

iv. The device should be bio-compatible, and tiny.

v. The device should be compatible to use, small, cheap, and capable of repeated use.

1.3.3 General characteristics of a biosensor

There are four characteristics points of a biosensor to remember. These are as follows:

i. Linearity: linearity of a biosensor should be high for the detection of a high concentration of substrate.

ii. Sensitivity: the relation between the substrate concentration response and the value of the electrode.

iii. Selectivity: chemical interference must be minimalized for procurement of the accurate results.

iv. Response time: 95% of the response mediated time is necessary.

1.3.4 Chemosensor versus biosensor

A chemosensor or molecular sensor is a structure of a molecule (inorganic or organic compounds) which can be used for sensing of an analyte to produce a signal or a detectable change. Chemosensor describes molecule of synthetic origin where the signal can be defined with the presence of energy or matter. A chemosensor is a sort of an analytical device, which are used in daily life and have been functional to countless parts viz in physiology, immunology, biochemistry, chemistry, etc.

Chemosensors are synthetic analogues of biosensors, the difference being that biosensors consolidate biological receptors, for example, large biopolymers, aptamers, or antibodies.

Notably, a chromo-fluorogenic sensor contains of three different fragments (Fig. 1.3):

Fig. 1.3 Mechanism of signaling for chemosensor and biosensor [9].

(1) A signaling part, whose properties should be transformed upon interacting with the analyte under experiment giving in the development of an optical signal, (2) a binding unit or receptor that essentially interacts or binds with the analyte, and (3) a linking group that links the two former parts (in some cases spacer is absent and two parts are combined) [9].

1.3.5 Applications of biosensor

Biosensors cover a wide range of applicability such as:

1.3.6 Advantages of biosensors

Biosensors are exceedingly useful because of the following reasons:

i. High sensitivity

ii. Eco-friendly

iii. Simple fabrication

iv. Simple monitoring device in-situ

v. Mass production is easier

vi. Highly specific towards analyte

vii. Low cost

viii. Fast response

ix. Accurate measurement

1.3.7 Disadvantages of biosensors

Despite being crucial for so many real applications, biosensor possesses certain limitations:

i. Poor reproducibility

ii. Generally, temperature dependent system

iii. pH influences the performance of a biosensor

iv. Requires sample preparation

1.4 Types of biosensors

Biosensors can be subdivided into many types based on its components such as bioreceptor and transducer:

Calorimetric biosensor can be used when the enzyme-catalyzed reaction is exothermic, two thermistors may be used to quantity the difference in resistance between reactant and product and hereafter the concentration of the analyte.

Electrochemical biosensor: many chemical reactions produce or consume ions or electrons which in turn cause some change in the electrical properties of the solution which can be sensed out and used as measuring parameter (Fig. 1.4). Electrochemical biosensors can be further classified as

i. Amperometric biosensor (for applied current), where transfer of electrons in a redox reaction noticed when a potential is applied between two electrodes.

ii. Potentiometric biosensor (for voltage), where change in the circulation of charge is observed by means of ion-selective electrodes like pH-meters.

iii. Conductometric biosensor for the measurement of impedance.

Fig. 1.4 Signaling fate of an electrochemical biosensor.

Optical biosensors can be subdivided into two major parts: (1) Colorimetric, which measure change in light adsorption in terms of color while reactants are converted to products. (2) Photometric, where photon output for a fluorescent/luminescent fate can be perceived with photodiode systems or photomultiplier tubes (PMT) [13].

1.5 Conclusion

At a glance, this chapter summarizes the concept of sensors and more specifically biosensors. These can be of various organic ligands, metal complexes, nanomaterials, composites, biomaterials, and but not limited to small molecules. Furthermore, the properties of the biosensors are explained, which are in fact too unique to facilitate the important uses in daily life. Notably, biosensors can be further used for some vital chemical, biological, as well as material applications. This chapter also deals with the various types of biosensors that have been widely used so far to find out a solution for crucial real time issues (Fig. 1.5).

Fig. 1.5 Stepwise biosensor processing for the detection and/or quantification of an analyte.

Herein, this chapter not only useful for the researchers of biosensors but also for the broad audience in the field of multidisciplinary research.

Declaration

The author declares no financial interest for his contribution to this chapter.

Acknowledgement

Dr. Bidyut Kumar Kundu gladly thanks his mother, Champa Kundu for her constant support and encouragement to carry out this work.

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