Medical applications of infrared thermography: A review.

Radiation therapy (RT) including external beam radiotherapy (EBRT) and internal radioisotope therapy (RIT) has been widely used for clinical cancer treatment. However, owing to the low radiation absorption of tumors, high doses of ionizing radiations are often needed during RT, leading to severe damages to normal tissues adjacent to tumors. Meanwhile, the RT efficacies are limited by different mechanisms, among which the tumor hypoxia-associated radiation resistance is a well-known one, as there exists hypoxia inside most solid tumors while oxygen is essential to enhance radiation-induced DNA damages. With the development in nanotechnology, there have been great interests in using nanomedicine strategies to enhance radiation responses of tumors. Nanomaterials containing high-Z elements to absorb radiation rays (e.g. X-ray) can act as radio-sensitizers to deposit radiation energy within tumors and promote treatment efficacy. Nanoscale carriers are able to deliver therapeutic radioisotopes into tumors for internal RIT, or chemotherapeutic drugs for synergistically combined chemo-radiotherapy. As uncovered in recent studies, the tumor microenvironment could be modulated by various nanomedicine approaches to overcome hypoxia-associated radiation resistance. Herein, the authors will summarize the applications of nanomedicine for RT cancer treatment, and pay particular attention to the latest development of 'advanced materials' for enhanced cancer RT.

Emerging Nanotechnology and Advanced Materials for Cancer Radiation Therapy.

Significance Efficient thermal transport is critical for applications ranging from electronics and energy to advanced manufacturing and transportation; it is essential in emerging domains like wearable computing and soft robotics, which require thermally conductive materials that are also soft and stretchable. However, heat transport within soft materials is limited by the dynamics of phonon transport, which results in a trade-off between thermal conductivity and compliance. We overcome this by engineering an elastomer composite embedded with elongated inclusions of liquid metal (LM) that function as thermally conductive pathways. These composites exhibit an extraordinary combination of low stiffness (<100 kPa), high strain limit (>600%), and metal-like thermal conductivity (up to 9.8 W⋅m−1⋅K−1) that far exceeds any other soft materials. Soft dielectric materials typically exhibit poor heat transfer properties due to the dynamics of phonon transport, which constrain thermal conductivity (k) to decrease monotonically with decreasing elastic modulus (E). This thermal−mechanical trade-off is limiting for wearable computing, soft robotics, and other emerging applications that require materials with both high thermal conductivity and low mechanical stiffness. Here, we overcome this constraint with an electrically insulating composite that exhibits an unprecedented combination of metal-like thermal conductivity, an elastic compliance similar to soft biological tissue (Young’s modulus < 100 kPa), and the capability to undergo extreme deformations (>600% strain). By incorporating liquid metal (LM) microdroplets into a soft elastomer, we achieve a ∼25× increase in thermal conductivity (4.7 ± 0.2 W⋅m−1⋅K−1) over the base polymer (0.20 ± 0.01 W⋅m−1·K−1) under stress-free conditions and a ∼50× increase (9.8 ± 0.8 W⋅m−1·K−1) when strained. This exceptional combination of thermal and mechanical properties is enabled by a unique thermal−mechanical coupling that exploits the deformability of the LM inclusions to create thermally conductive pathways in situ. Moreover, these materials offer possibilities for passive heat exchange in stretchable electronics and bioinspired robotics, which we demonstrate through the rapid heat dissipation of an elastomer-mounted extreme high-power LED lamp and a swimming soft robot.

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High thermal conductivity in soft elastomers with elongated liquid metal inclusions.

Nanomedicines can be used for a variety of cancer therapies including tumor-targeted drug delivery, hyperthermia, and photodynamic therapy. Poly (lactic-co-glycolic acid) (PLGA)-based materials are frequently used in such setups. This review article gives an overview of the properties of previously reported PLGA nanoparticles (NPs), their behavior in biological systems, and their use for cancer therapy. Strategies are emphasized to target PLGA NPs to the tumor site passively and actively. Furthermore, combination therapies are introduced that enhance the accumulation of NPs and, thereby, their therapeutic efficacy. In this context, the huge number of reports on PLGA NPs used as drug delivery systems in cancer treatment highlight the potential of PLGA NPs as drug carriers for cancer therapeutics and encourage further translational research.

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PLGA-Based Nanoparticles in Cancer Treatment.

Binary mixtures of liquid metal (LM) or low-melting-point alloy (LMPA) in an elastomeric or fluidic carrier medium can exhibit unique combinations of electrical, thermal, and mechanical properties. This emerging class of soft multifunctional composites have potential applications in wearable computing, bio-inspired robotics, and shape-programmable architectures. The dispersion phase can range from dilute droplets to connected networks that support electrical conductivity. In contrast to deterministically patterned LM microfluidics, LMPA- and LM-embedded elastomer (LMEE) composites are statistically homogenous and exhibit effective bulk properties. Eutectic Ga-In (EGaIn) and Ga-In-Sn (Galinstan) alloys are typically used due to their high conductivity, low viscosity, negligible nontoxicity, and ability to wet to nonmetallic materials. Because they are liquid-phase, these alloys can alter the electrical and thermal properties of the composite while preserving the mechanics of the surrounding medium. For composites with LMPA inclusions (e.g., Field's metal, Pb-based solder), mechanical rigidity can be actively tuned with external heating or electrical activation. This progress report, reviews recent experimental and theoretical studies of this emerging class of soft material architectures and identifies current technical challenges and opportunities for further advancement.

Soft Multifunctional Composites and Emulsions with Liquid Metals

Therapeutic hyperthermia is a procedure that involves heating tissues to a higher temperature level, typically ranging from 41oC to 45oC. Its combination with radiotherapy and/or chemotherapy has been performed for many years, with remarkable success in treating advanced and recurrent cancers. The current hyperthermia strate- gies generally include local, regional, and whole-body hyperthermia, which can be implemented by many heating methods, such as microwave, radiofrequency, laser, and ultrasound. There are several hyperthermic treatment modalities in conjunction with radiotherapy/chemotherapy. Numerous studies have attempted to explain the mechanisms of thermosensitization from radiation and chemotherapy; however, a generalized standard for determining an optimal hyperthermia modality combined with radiotherapy/chemotherapy has not been established, so more research is needed. Fortunately, phase II/III clinical trials have demonstrated that hyperthermia combination therapy is beneficial for local tumor control and survival in patients with high-risk tumors of different types. The aim of this article is to present a comprehensive review of the latest advances in tumor hyperthermia combined with radiotherapy and/ or chemotherapy. We specifically focus on synergistic cellular and molecular mechanisms, thermal dose, treatment sequence, monitoring and imaging, and clinical outcomes of the combination therapy. The role of nanoparticles in sensitization during radio-/chemotherapy is also evaluated. Finally, research challenges and future trends in the related areas are presented.

A review of hyperthermia combined with radiotherapy/chemotherapy on malignant tumors.

Semi-Liquid-Metal-(Ni-EGaIn)-Based Ultraconformable Electronic Tattoo

Thermally Conductive and Highly Electrically Resistive Grease Through Homogeneously Dispersing Liquid Metal Droplets Inside Methyl Silicone Oil

Numerical simulation of selective freezing of target biological tissues following injection of solutions with specific thermal properties.

The main difficulties encountered in cryosurgery are the unknowns on the extent of the irregular shape of the frozen region, the direction of ice growth, and the temperature distribution within the ice balls during the freezing process. In this study, a numerical algorithm based on the dual reciprocity boundary element method (DRBEM) is developed to solve multidimensional phase change problem of biological tissues subject to cryosurgery. The tissues are treated as nonideal materials, freezing over a temperature range, and the effects of blood perfusion and metabolic heat generation in the unfrozen tissues are also taken into account in the heat transfer model. The accuracy of this DRBEM algorithm is validated through comparisons of the calculation results with the one-dimensional numerical solutions by the finite difference method. Comprehensive analyses are performed respectively, on the freezing behaviors of normal biological tissue and diseased tissue with tumors. For treatment of large tumors where large cooling power is required, a single probe will not be able to address a sufficiently large volume. On this account, the freezing problems by two- and three-cryoprobe system are solved for illustration purpose. The present algorithm can serve as a useful tool for post-treatment planning in cryosurgery.

Zhong-Shan Deng

Papers

A review of hyperthermia combined with radiotherapy/chemotherapy on malignant tumors.

Semi-Liquid-Metal-(Ni-EGaIn)-Based Ultraconformable Electronic Tattoo

Thermally Conductive and Highly Electrically Resistive Grease Through Homogeneously Dispersing Liquid Metal Droplets Inside Methyl Silicone Oil

Numerical simulation of selective freezing of target biological tissues following injection of solutions with specific thermal properties.

Modeling of multidimensional freezing problem during cryosurgery by the dual reciprocity boundary element method