Photothermal Therapy: Advances in Targeted Cancer Treatment With Nanotechnology and Heat Therapy

By Fouad Sabry

Photothermal Therapy, part of the Nanomedicine series, delves into the cuttingedge applications of nanotechnology in medicine. This book provides a comprehensive exploration of how nanomaterials, specifically nanoparticles, are revolutionizing the field of cancer treatment and other therapeutic approaches. Whether you're a professional, student, or simply an enthusiast, this book will equip you with valuable insights into the integration of nanomedicine with photothermal therapy, offering both depth and clarity on the subject.

Chapters Brief Overview:

1: Photothermal therapy: This chapter introduces the concept of photothermal therapy, highlighting its potential in noninvasive cancer treatment.

2: Nanomedicine: Focuses on the growing role of nanomedicine in diagnosing, treating, and preventing diseases at the molecular level.

3: Gold nanoparticles in chemotherapy: Explores the use of gold nanoparticles to enhance the efficacy of chemotherapy, targeting cancer cells with precision.

4: Nanoparticle drug delivery: Discusses the advancements in drug delivery systems using nanoparticles, improving the specificity and efficiency of treatments.

5: Magneticplasmonic bifunctional nanoparticles: Examines the dual functionality of magnetic and plasmonic nanoparticles for targeted drug delivery and imaging.

6: Colloidal gold: Investigates the properties and applications of colloidal gold in biomedical treatments, particularly in diagnostics.

7: Carbon quantum dot: Describes carbon quantum dots and their role in photothermal therapy and drug delivery systems.

8: Localized surface plasmon: Provides an understanding of localized surface plasmon resonance and its applications in nanomedicine.

9: Nanocarrier: Details the use of nanocarriers in drug delivery, ensuring targeted and controlled release of therapeutic agents.

10: Applications of nanotechnology: A broad look at various nanotechnology applications in the medical field, from imaging to treatment.

11: Nanoshell: Focuses on nanoshell technology and its use in enhancing the photothermal effect for cancer therapy.

12: Plasmonic nanoparticles: Delves into the characteristics and medical applications of plasmonic nanoparticles in diagnostics and therapy.

13: Artificial enzyme: Explores the concept of artificial enzymes in nanomedicine, potentially replacing natural enzymes in biological processes.

14: HadiyahNicole Green: Highlights the work of Dr. HadiyahNicole Green, a pioneer in the field of nanomedicine and cancer treatment.

15: Nanomaterials: Examines various nanomaterials used in medical applications, discussing their potential in diagnostics and treatment.

16: Upconverting nanoparticles: Investigates upconverting nanoparticles and their role in enhancing the effectiveness of photothermal therapy.

17: Photosensitizer: Discusses photosensitizers used in combination with photothermal therapy for improved cancer treatment outcomes.

18: Carbon nanotubes in medicine: Reviews the medical applications of carbon nanotubes, focusing on their potential in drug delivery and imaging.

19: Gold nanocage: Explores the role of gold nanocages in enhancing photothermal therapy and drug delivery systems.

20: Photoimmunotherapy: Investigates photoimmunotherapy, which combines photothermal therapy with immunotherapy for improved cancer treatment.

21: JiXin Cheng: Concludes the book with an exploration of JiXin Cheng’s work, showcasing the future of nanomedicine in healthcare.

• Language: English
• Publisher: One Billion Knowledgeable
• Release date: Mar 14, 2025

Book preview

Chapter 1: Photothermal therapy

Photothermal therapy, often known as PTT, is a term that describes the therapeutic application of electromagnetic radiation, typically in the form of infrared wavelengths, with the purpose of treating a variety of medical problems, including cancer. The neurotherapy in question is an extension of photodynamic therapy, which involves the stimulation of a photosensitizer with a particular band of light source. This activation causes the sensitizer to enter an excited state, at which point it releases vibrational energy in the form of heat, which is what ultimately takes the lives of the cells that are being targeted.

Photothermal therapy, in contrast to photodynamic therapy, does not require oxygen in order to interact with the cells or tissues that are the focus of the treatment. In addition, recent research has demonstrated that photothermal therapy can make use of longer wavelength light, which is lower in energy and, as a result, less damaging to other cells and tissues.

On the nanoscale, the majority of the materials of interest that are now being researched for photothermal therapy are discovered. Because of the higher permeability and retention effect that is observed with particles in a particular size range (usually between 20 and 300 nm), this is one of the primary reasons why this is the case. In tumor tissue, molecules that fall within this range have been seen to accumulate more frequently than in other tissues. The formation of a tumor necessitates the formation of new blood vessels in order to provide the necessary fuel for the tumor's growth. These new blood vessels in or around the tumor exhibit distinct characteristics in comparison to regular blood vessels, including inadequate lymphatic drainage and a chaotic and leaky vasculature. As a result of these circumstances, the concentration of particular particles in a tumor is much higher than the concentration in the rest of the body compared to the tumor.

Huang and colleagues conducted research to determine whether or not it would be possible to use gold nanorods for the imaging of cancer cells as well as for photothermal therapy. The authors attached antibodies, specifically anti-EGFR monoclonal antibodies, to the surface of gold nanorods. This made it possible for the gold nanorods to bind specifically to certain malignant cancer cells, specifically HSC and HOC malignant cells. Immediately following the incubation of the cells with the gold nanorods, an 800 nm Ti:sapphire laser was utilized to irradiate the cells at a range of strength levels. A successful eradication of the cancer cells that were malignant was reported by the authors, while the cells that were not malignant were not affected.

When AuNRs are subjected to NIR light, the free electrons of the AuNR have the ability to collectively and coherently oscillate as a result of the light's oscillating electromagnetic field. Alterations to the dimensions and configuration of AuNRs result in a shift in the wavelength that is absorbed. Due to the fact that biological tissue is optically transparent at wavelengths between 700 and 1000 nm, this would be the ideal wavelength range. Despite the fact that all AuNP are sensitive to changes in their form and size, the properties of Au nanorods are very sensitive to any change in any of their dimensions, including their length and breadth as well as their aspect ratio. The formation of a dipole oscillation in the direction of the electric field is observed in a metal nanoparticle (NP) when light is shone on the NP. This particular frequency is referred to as the surface plasmon resonance (SPR) when the oscillation reaches its point of maximum intensity. AuNR have two SPR spectrum bands: one in the near-infrared region, which is caused by its longitudinal oscillation, which tends to be stronger with a longer wavelength, and one in the visible area, which is caused by the transverse electronic oscillation, which tends to be weaker with a shorter wavelength. Both of these bands are caused by the AuNR electromagnetic wave. The increase in light absorption for the particle can be attributed to the properties of the SPR mechanism. As the aspect ratio of the AuNR grows, the wavelength of the absorption that occurs is redshifted, and the efficiency with which light scatters is increased.  The electrons that are stimulated by the near-infrared radiation lose energy rapidly after being absorbed by electron-electron collisions. As these electrons relax back down, the energy is released as a phonon, which subsequently heats the environment of the AuNP, which in the context of cancer treatments would be the malignant cells. It is possible to observe this process when a laser is applied to the AuNP in a continuous wave condition. In most cases, the melting or ablation of the AuNP particle is the reaction that occurs when pulsed laser light beams are used. Continuous wave lasers are able to heat bigger areas at the same time, and they take minutes to operate, in contrast to pulsed lasers, which only require a single pulse during the course of their operation.

Nanoshells made of gold, wherein silica nanoparticles are coated with a very thin layer of gold. PEG linkers have been utilized in order to attach antibodies (anti-HER2 or anti-IgG) to the target. A laser with a wavelength of 820 nm was utilized to irradiate the SKBr3 cancer cells after they had been incubated with the gold nanoshells. During the laser treatment, the only cells that were harmed were those that had been treated with gold nanoshells that had been coupled with the specific antibody (anti-HER2).  Furthermore, gold nanoshells can be classified as a layer of gold atop liposomes, which serves as a soft template. In this scenario, the medication may also be enclosed inside and/or in a bilayer, and the release may be triggered by laser light using any of these procedures.

The failure of nanoparticles-mediated PTT to be successfully translated into clinical practice can mostly be attributed to concerns with the nanoparticles' retention in the body. Increasing the size of anisotropic nanomaterials to a maximum of 150 nanometers allows for the optical response of these materials to be tuned in the near-infrared frequency range. On the other hand, the hepatobiliary pathway causes the body to excrete non-biodegradable nanoparticles of noble metals that are larger than 10 nanometers in a manner that is both slow and inefficient during the process. To prevent metal persistence, it is commonly employed to decrease the size of nanoparticles to a level below the threshold for renal clearance, which is referred to as ultrasmall nanoparticles (USNPs). In the meantime, the maximal light-to-heat transduction occurs for nanoparticles that are less than 5 nanometers in size. The surface plasmon of excretable gold USNPs, on the other hand, is located in the ultraviolet and visible range, which is a significant distance from the initial biological windows. This drastically restricts the possible applications of these systems in PTT.

By utilizing ultrasmall-in-nano structures that are composed of metal USNPs embedded in biodegradable silica nanocapsules, it has been possible to integrate the process of metal excretion with NIR-triggered photothermal therapy (PTT). tNAs are the first NIR-absorbing plasmonic ultrasmall-in-nano platforms that have been disclosed. They integrate three key features: i) photothermal conversion efficacy that is ideal for hyperthermia; ii) numerous photothermal sequences; and iii) renal excretion of the building blocks following the therapeutic action. At the present time, the therapeutic impact of tNA has been evaluated on valuable three-dimensional models of human pancreatic adenocarcinoma.

Graphene has the potential to be used in photothermal therapy. In order to irradiate the tumor locations on mice for a period of five minutes, a laser with a wavelength of 808 nm and a power density of 2 W/cm2 was utilized. The scientists have mentioned that the power densities of lasers that are utilized to heat gold nanorods range from two to four watts per square centimeter. Therefore, in order to photothermally ablate tumors, these nanoscale graphene sheets require a laser power that is on the lower end of the range that is used with gold nanoparticles.

Yang et al. incorporated the promising results regarding nanoscale reduced graphene oxide that Robinson et al. reported into another in vivo mice study in the year 2012. The therapeutic treatment that was utilized in this study involved the utilization of nanoscale reduced graphene oxide sheets, which were nearly identical to the sheets that were utilized by Robinson et al. (but without any active targeting sequences attached). This was accomplished by successfully irradiating nanoscale reduced graphene oxide sheets in order to entirely eradicate the malignancies that were being targeted. Particularly noteworthy is the fact that the needed power density of the 808 nm laser was decreased to 0.15 W/cm2, which is an order of magnitude lower than the power densities that were previously anticipated. Based on the findings of this work, it is clear that nanoscale reduced graphene oxide sheets are more effective than both nanoscale graphene sheets and gold