Photothermal Applications Research Articles

Enhanced Interband Transition in FeCoNiAlTi High‐Entropy Alloy for Ultrafast Nonlinear Optical Applications

AbstractHigh‐entropy alloys (HEAs) possess superior mechanical, thermal, and electronic properties, which attract great interest in the fields of photothermal, electrocatalysis, and magnetic applications. Herein, the nonlinear optical properties of FeCoNiAlTi HEA with a large specific surface area for the first time is investigated. Owing to the strong d–d interaction, the interband transition near the Fermi level could be enhanced in HEAs, leading to broadband optical absorption. Excitation with the picosecond laser source, the FeCoNiAlTi HEA possesses saturable absorption with a large modulation depth of 7.61% and 30.47% at 1 and 1.5 µm, respectively. Furthermore, at the higher excitation level at 1.5 µm, the saturable absorber exhibits a typical reverse saturable absorption property. Subsequently, the FeCoNiAlTi HEA on the tapered fiber first serves as the saturable absorber in the Yb‐doped fiber laser and the Er‐doped fiber laser, leading to the noise‐like pulses at 1 µm, and the stable Q‐switching, conventional soliton, and dissipative soliton resonance mode‐locking operations at 1.5 µm. This work confirms that the enhanced saturable absorption in HEAs can endow the high‐performance ultrashort pulse generation.

Angelica keiskei: A promising antioxidant and anticancer agent for Photothermal mediated drug delivery applications

Angelica keiskei: A promising antioxidant and anticancer agent for Photothermal mediated drug delivery applications

Plasmonic Magnesium Nanoparticles Are Efficient Nanoheaters.

Understanding and guiding light at the nanoscale can significantly impact society, for instance, by facilitating the development of efficient, sustainable, and/or cost-effective technologies. One emergent branch of nanotechnology exploits the conversion of light into heat, where heat is subsequently harnessed for various applications including therapeutics, heat-driven chemistries, and solar heating. Gold nanoparticles are overwhelmingly the most common material for plasmon-assisted photothermal applications; yet magnesium nanoparticles present a compelling alternative due to their low cost and superior biocompatibility. Herein, we measured the heat generated and quantified the photothermal efficiency of the gold and magnesium nanoparticle suspensions. Photothermal transduction experiments and optical and thermal simulations of different sizes and shapes of gold and magnesium nanoparticles showed that magnesium is more efficient at converting light into heat compared to gold at near-infrared wavelengths, thus demonstrating that magnesium nanoparticles are a promising new class of inexpensive, biodegradable photothermal platforms.

Chiral Au nanostars for SERS sensing of enantiomers discrimination, multibacteria recognition and photothermal antibacterial application

The recognition and detection of chirality is of great significance in the fields of chemistry, pharmacy and biomedicine. In this work, we fabricated a chiral Au nanostars (C-AuNSs) with intense chiroptical responses and surface-enhanced Raman scattering (SERS) features by controlling chiral ligand D-/L-cysteine (Cys) concentration. The proposed chiral AuNSs can be applied for the enantiodiscrimination of amino acid based on SERS-chiral anisotropy (SERS-ChA) effect, in which homochiral amino acid has distinct affinities to the C-AuNSs of homogeneous handedness. By demonstrating selective affinity of D-AuNSs with D-glutamic acid (D-Glu) on bacterial peptidoglycan, we further realized effective identification of multiple bacteria according to SERS specific bacterial “fingerprints” by discriminant analysis (DA). More importantly, D-AuNSs can also be carried out to classify two bacterial pathogens (E. coli and S. aureus) in serum samples, as well as differentiate the infected patients from healthy subjects successfully with great accuracy. Benefiting from intrinsic photothermal capability, chiral AuNSs exhibited high efficiency in killing of bacteria and disrupting of biofilms through a synergistic chemotherapy and phototherapy (PTT) functions. Altogether, the chiral AuNSs provides a novel strategy for SERS discrimination of enantiomer and bacteria, as well as incorporation of photothermal bacterial elimination, contributing to further broaden the chiral nanomaterials-based application.

Fabrication of Au-Ag Bimetallic Nanoparticles Using Pulsed Laser Ablation for Medical Applications: A Review.

In recent years, the synthesis of Au-Ag bimetallic nanoparticles has garnered immense attention due to their potential applications in diverse fields, particularly in the realm of medicine and healthcare. The development of efficient synthesis methods is crucial in harnessing their unique properties for medical applications. Among the synthesis methods, pulsed laser ablation in a liquid environment has emerged as a robust and versatile method for precisely tailoring the synthesis of bimetallic nanoparticles. This manuscript provides an overview of the fundamentals of the pulsed laser ablation in a liquid method, elucidating the critical factors involved. It comprehensively explores the pivotal factors influencing Au-Ag bimetallic nanoparticle synthesis, delving into the material composition, laser parameters, and environmental conditions. Furthermore, this review highlights the promising strides made in antibacterial, photothermal, and diagnostic applications. Despite the remarkable progress, the manuscript also outlines the existing limitations and challenges in this advanced synthesis technique. By providing a thorough examination of the current state of research, this review aims to pave the way for future innovations in the field, driving the development of novel, safe, and effective medical technologies based on Au-Ag bimetallic nanoparticles.

Experimental study of a linear Fresnel reflection solar concentrating system

Introduction: In the field of solar energy utilization, the construction of low cost and easy to process large concentrated photothermal system is a scientific problem to be solved. A linear Fresnel reflection solar concentrator is proposed in this paper.Methods: The position, tilt angle and width of the glass mirrors placed in the same plane are different to ensure that all the reflected light falls on the flat focal plane or cylindrical focal surface. According to the focusing principle of the concentrator, two experimental system platforms ware built. When a flat focal plane is used to receive radiation from the sun, the intensity distribution of focal plane light spot is uniform in theory.Results: The CCD measurement method is used to analyze the concentrated light spot under experimental conditions, and it is proved that the energy flux density on the focal plane is uniform. Placing monocrystalline silicon cells on the focal plane, the experimental results of p-v power generation voltammetry show that the power generation efficiency of monocrystalline silicon cell does not decrease due to the uniform solar energy density, which can reach 17.1%. The photothermal experiment is carried out by using one-dimensional tracking mode of sunlight. The concentrator reflects the sun’s rays onto the vacuum collector tubes, heating the heat conduction oil flow in. The thermocouple measures the temperature of the heat conduction oil at the inlet and outlet of the vacuum collector tubes. The experimental photothermal conversion efficiency of this concentrator was analyzed and calculated through multiple groups of photothermal experiments, and compared with the theoretical concentrator efficiency. With two collector tubes in series, the theoretical photothermal conversion efficiency reaches 0.8 and the experimental photothermal conversion efficiency reaches about 0.74.Discussion: Because of its good concentrating performance and low cost, this type concentrator can be widely used in photothermal and photovoltaic applications.

Facile, catalyst-free, and high enthalpy PEG-based phase change composite for use in photothermal conversion and waste heat recovery

The poor shape stability, low thermal storage density, and complex process confronted in fabricating high-performance phase change composites (PCCs) via the chemical cross-linking technology. Herein, PEG-based shape stability PCC (SSPCC) with high enthalpy and good shape stability was obtained using a facile one-pot method without additional catalysts. The reliable three-dimensional cross-linked structure formed by the interaction of epoxy resin and curing agent binds the movement of PEG molecular chains, which simultaneously in coupled with the stronger hydrogen bonding between PEG and cross-linked products to endow the as-prepared SSPCC with excellent shape stability, thermal stability, durability, and high thermal storage density (160.8 J/g). Moreover, the Raman spectra clearly presented the interaction force and phase morphology distribution between PEG and the skeleton structure. SSPCC with the high relative enthalpy efficiency and melt enthalpy can play an essential role in photothermal applications, while the facile manufacturing process free from additional organic solvents or high temperature, highlighting its green and sustainable features. Additionally, the photothermal transport and thermostatic effects of the SSPCCs show great potential for application in waste heat recovery, which can maintain higher temperatures for a long time. Totally, such SSPCC with reliable and distinguished phase change properties ensure a wide range of potential applications, while the easy-to-prepare and low-cost fabrication method provides an inspiring strategy for alternative SSPCC development.

H2O2 self-supplying Mo/Fe@CuO2 nanozyme with NIR light enhanced catalytic activity and photothermal synergistic antibacterial application

Nanozymes have drawn increasing attention due to unique enzyme-mimic catalytic activities for the treatment of bacterial infections. Herein, a novel tri-metal nanozyme for synergistic eradication of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was generated by Mo/Fe doped carbon dots (Mo/Fe-CDs) wrapping copper peroxide (CuO2) nanozyme (Mo/Fe@CuO2). Mo/Fe@CuO2 showed near-infrared (NIR) light-enhanced peroxidase-like catalytic activity, and H2O2 self-supply to promote the generation of reactive oxygen species (ROS) for highly efficient antibacterial photothermal therapy. The CuO2 could generate H2O2 in the acidic microenvironment, and Mo/Fe-CDs consequently could convert H2O2 to hydroxyl radicals (·OH), resulting in the improvement of sterilization efficiency. Interestingly, Mo/Fe-CDs could activate the transformation of Cu2+ to Cu+ through the co-catalytic reaction based on the Mo4+/Mo6+ and Fe3+/Fe2+ redox couples, and provided photonic hyperthermia (PTT) to enhance the peroxidase-like activity. Meanwhile, Mo/Fe@CuO2 showed glutathione (GSH) oxidase-like activity, which can achieve the depletion of glutathione (GSH) in bacteria, thus significantly improving the bactericidal effect. The collaborative eradication of bacteria, through innovative metal carbon-based nanozyme technology, provides a powerful and feasible approach to treating bacterial infections that threaten human health.

Polybenzoxazines as new photothermal therapy agents

To make photothermal therapy an attractive alternative to conventional cancer treatments, the development of novel photothermal agents with enhanced properties is demanded. To tackle this challenge, herein we explored the use of polybenzoxazines, a well-known class of phenolic resins. Two different types of polybenzoxazine materials were prepared as potential photothermal agents: water-soluble polybenzoxazines as well as nanoparticles of hydrophobic polybenzoxazines, which can be generated in situ by polymer addition to cell culture medium. For both systems, irradiation with visible light led to significant photothermal effects, whose application to photoinduce human breast cancer cell’s death was investigated in vitro. The best results were obtained for polybenzoxazine nanostructures, which exhibited successful cell internalization, minimal cytotoxicity in the dark and efficient photothermal killing of cancer cells upon illumination with high-penetrating red light. In combination with their low cost and facile preparation, this makes these polymer nanomaterials highly promising for photothermal therapy applications.

Sulfur-Doped NiFe Hydroxide Nanobowls with Wrinkling Patterns for Photothermal Cancer Therapy.

Hierarchical multiscale wrinkling nanostructures have shown great promise for many biomedical applications, such as cancer diagnosis and therapy. However, synthesizing these materials with precise control remains challenging. Here, we report a sulfur doping strategy to synthesize sub-1 nm NiFe hydroxide ultrathin nanosheets (S-NiFe HUNs). The introduction of sulfur affects the reduction of the band gap and the adjustment of the electronic structure, thereby improving the light absorption ability of the S-NiFe HUNs. Additionally, S-NiFe HUNs show a multilayered nanobowl-like structure that enables multiple reflections of incident light inside the nanostructure, which improved the utilization of incident light and achieved high photothermal conversion. As a result, the as-prepared product with hydrophilic modification (dS-NiFe HUNs) demonstrated enhanced tumor-killing ability in vitro. In a mouse model of breast cancer, dS-NiFe HUNs combined with near-infrared light irradiation greatly inhibited tumor growth and prolonged the mice survival. Altogether, our study demonstrates the great potential of dS-NiFe HUNs for cancer photothermal therapy applications.

Preparation of polyvinyl alcohol/chitosan nanofibrous films incorporating graphene oxide and lanthanum chloride by electrospinning method for potential photothermal and chemical synergistic antibacterial applications in wound dressings

Electrospun fibres have been widely used as skin dressings due to their unique structur. However, due to the lack of intrinsic antimicrobial activity, it is easy for the wound to become infected. Bacterial infection, which leads to chronic inflammation, severely hinders the normal process of skin regeneration. In this study, a polyvinyl alcohol/chitosan (PVA/CS) composite films with chemical sterilization and near-infrared (NIR) photothermal antibacterial activity was fabricated by electrospinning. Graphene oxide (GO), a photosensitiser, was incorporated into the films, and lanthanum chloride (Lacl3) as a chemical antibacterial agent was also doped in the electrospun films. The structure, morphology, mechanical properties, wettability, and antimicrobial and photothermal antibacterial activity of the PVA/CS-based fibre films were investigated. The results showed that the addition of Lacl3 to the PVA/CS/GO nanofibres (PVA/CS/GO-La) improved the hydrophilicity, tensile strength and resistance to elastic deformation of the nanofibres. The PVA/CS/GO-La12.5 mM sample exhibited the best antibacterial performance, showing high inhibition against Staphylococcus aureus (82% antibacterial efficacy) and Escherichia coli (99.7% antibacterial efficacy). Furthermore, the antibacterial efficacy of the films surface was further enhanced after exposure to NIR light (808 nm, 0.01 W) for 20 min. In addition, the nanofibre films showed no cytotoxicity against human skin fibroblasts (HSFs), indicating its potential application in the field of broad-spectrum antibacterial materials.

Flexible phase-change composite films for infrared thermal camouflage and photothermal energy storage

To meet the requirement of multipurpose applications in infrared thermal camouflage and solar photothermal energy storage, we have developed a series of multifunctional composite films based on polyurethane (PU) as a flexible matrix and double-layered phase-change microcapsules as an additive. The double-layered microcapsules were first constructed by encapsulating n-docosane as a phase-change material in a titanium dioxide shell, followed by depositing a polyaniline (PANi) functional layer. Then, the microcapsules were incorporated into the PU matrix to form the composite films through in situ polycondensation. A high latent heat capacity of over 130 J g−1 was achieved by the microcapsules as a result of a high n-docosane loading. This can generate an effective thermal buffer for the composite films and thus endow them with a good thermal camouflage capability. The composite films also show good solar energy-storage performance thanks to their superior sunlight absorptivity derived from the PANi coating layer of the microcapsules. The composite films present a much higher surface temperature (68.6 °C) than pure PU film (41.9 °C) under simulated sunlight irradiation for 1488 s. In addition, the composite films exhibit a self-cleaning surface and high flexibility. Integrating the double-layered microcapsules and flexible PU matrix may provide an innovative strategy for developing flexible functional films for infrared thermal camouflage and photothermal energy storage applications.

Synergistic enhancement of optical properties in Ca/Ni co-doped LaFeO3 perovskite coatings enabling high-temperature photothermal conversion

Perovskite-type oxides (ABO3) are widely acknowledged as novel light-absorbing materials owing to their adaptable composition, distinctive oxidation states, and customizable physicochemical properties. In this study, we reported a series of A-site or A/B-sites doped LaFeO3-based ceramic coatings for photothermal conversion. An exhaustive investigation was undertaken to explore the effects of doping element on the microstructure, microchemistry, and optical properties of the ceramic coating. Among all the samples, the La0.5Ca0.5Fe0.95Ni0.05O3 coating exhibits the highest absorptivity in the solar spectrum (300–2500 nm) and in the wavelength range of 0.3–14 μm, reaching 92.2 % and 88.1 %, respectively. Furthermore, it demonstrated the superior photothermal conversion performance under solar and infrared radiation. Complementary first-principles calculations provide fundamental principles for comprehending the light absorption enhancement mechanisms in LaFeO3-based materials, revealing the complex interplays between crystal structure, band structure, and light absorption. The experimental findings, along with the results of first-principles calculations, demonstrate that the doping of Ca or Ca and Ni can effectively reduce the bandgaps and induce lattice distortions, thereby enhancing the light absorption in the visible and infrared wavebands. This work presents a facile method to prepare LaFeO3-based coatings with different morphologies, providing a novel option for high-temperature photothermal conversion applications.

Biomass aerogel composite containing BaTiO3 nanoparticles and MXene for highly sensitive self-powered sensor and photothermal antibacterial applications

Biomass aerogel materials are increasingly attracting researchers’ attention because of good biocompatibility of biomass materials and multiple functional features of aerogel materials. Herein, novel biomass aerogel composite was fabricated by doping hydroxylated barium titanate (BT-OH) nanoparticles and MXene in chitosan/bacterial cellulose (CB) aerogel by simple methods containing chemical modification, physical mixture and lyophilization. The novel aerogel composite named CB/BT-OH/MXene showed favorable piezoelectric properties and excellent photothermal antibacterial properties. The aerogel composite-based piezoelectric sensor displayed short response time (0.4 s), high response sensitivity (800 mV/N), and long cycle stability (over 1000 cycles), which could monitor various body movements, including fingers bending, speaking, wrist bending, elbow bending, smiling, and walking. Moreover, the aerogel composite possessed satisfactory photothermal conversion ability, which could reach 55 ℃ by 10 s of near-infrared irradiation (808 nm, 0.2 W/cm2), successfully achieving complete sterilization effect towards S. aureus and E. coli. The novel biomass aerogel composite may find its potential applications in wearable or implantable self-powered sensors with satisfactory antibacterial performance.

A Review on Microencapsulated Phase‐Change Materials: Preparation, Photothermal Conversion Performance, Energy Storage, and Application

The leakage‐prone disadvantage of pure phase change materials (PCMs) has hampered their practical application, and the encapsulation technology of PCMs has been favored for its ability to mitigate leakage. Combining large solar reserves with energy storage technology can increase the utilization of renewable energy and broaden the application of microencapsulated phase change materials (MEPCMs) in the field of solar energy. First, the fabrication technologies of MEPCMs, which include physical, chemical, and physical–chemical methods, have been comprehensively elaborated in this article. Second, the characteristics of different methods are also summarized. Then, the influences of MEPCMs properties on their thermal storage capacity have been clarified. This work shows the supercooling, phase separation, mechanical properties, encapsulation efficiency, and photothermal conversion performance of MEPCMs. Modification of MEPCMs by metal materials and their oxides, carbon, and semiconductor materials to improve the light absorption capacity. In addition, two‐dimensional materials such as MXene have been widely used to improve the photothermal properties of MEPCMs. Finally, the applications of MEPCMs in the construction, slurry, textile, and food industries are discussed. This work can provide some useful guidance for the optimization strategies of the photothermal conversion performance and practical applications of MEPCMs.

In situ formation of alginic acid-gold nanohybrids for application in cancer photothermal therapy.

Gold-based nanoparticles present excellent optical properties that propelled their widespread application in biomedicine, from bioimaging to photothermal applications. Nevertheless, commonly employed manufacturing methods for gold-based nanoparticles require long periods and laborious protocols that reduce cost-effectiveness and scalability. Herein, a novel methodology was used for producing gold-alginic acid nanohybrids (Au-Alg-NH) with photothermal capabilities. This was accomplished by promoting the in situ reduction and nucleation of gold ions throughout a matrix of alginic acid by using ascorbic acid. The results obtained reveal that the Au-Alg-NHs present a uniform size distribution and a spike-like shape. Moreover, the nanomaterials were capable to mediate a temperature increase of ≈11°C in response to the irradiation with a near-infrared region (NIR) laser (808nm, 1.7W cm-2 ). The in vitro assays showed that Au-Alg-NHs were able to perform a NIR light-triggered ablation of cancer cells (MCF-7), being observed a reduction in the cell viability to ≈27%. Therefore, the results demonstrate that this novel methodology holds the potential for producing Au-Alg-NH with photothermal capacity and higher translatability to the clinical practice, namely for cancer therapy.

Limits of antibacterial activity of triangular silver nanoplates and photothermal enhancement thereof for Bacillus subtilis

Currently, nanoparticles are being actively explored for antimicrobial applications involving variety of pathogens. Bacillus subtilis is a major concern considering its sporulation and biofilm formation capability which involves high bacteria loadings. Also, there is natural ability of B subtilis to adapt and develop resistance to the silver nanoparticles alone. So, this study reports the limits of antibacterial activity of triangular silver nanoplates (∆AgNPs) and further photothermal enhancement for B. subtilis ATCC 6051 for considerably high bacterial load of 2.5 × 107 to 5 × 108 CFU/ml.Triangular silver nanoplates were synthesized using one pot synthesis method and showed significant photothermal response i.e., ∼36 °C temperature rise on near infrared irradiation as well as photothermal stability. Triangular silver nanoplates alone showed absolute destruction for 2.5 × 107 CFU/ml initial B. subtilis load in 5 min. Whereas, for further higher bacterial loads, the antibacterial efficacy of ∆AgNPs is observed to be insignificant. For higher initial bacterial loads of 5 × 107 CFU/ml and 5 × 108 CFU/ml, photothermally enhanced triangular silver nanoplates resulted in complete destruction of bacteria in about 5 and 10 min, respectively. Antibacterial efficacy and mechanism of the destruction assessed via scanning electron microscopy and LIVE/DEAD assay confirmed morphological deformities. Further the generation of higher levels of reactive oxygen species is also confirmed due to photothermal activation of ∆AgNPs. The study concludes that ∆AgNPs alone are effective only up to bacterial load of 2.5 × 107 CFU/ml. Whereas, for higher bacterial loads of B. subtilis, photothermally activated ∆AgNPs lead to irreversible damage due to multiple targeting mechanisms leading to absolute elimination in short span of 5–10 min for the chosen irradiation conditions.Ultimately, this study demonstrates photothermally enhanced silver nanoplates as a potential antimicrobial agent for considerably high bacterial loads of B. subtilis. Overall, the broader window of considered high bacterial loadings and its irradiation by this technique shows the full-proof nature of photothermal applications for scenarios involving high cell density such as biofilms and wound infections etc. Further, the concept may be useful for sterilization or decontamination of samples, devices, etc. because B. subtilis and its spores are the challenges during sterilization.

Anti Stokes Thermometry of Plasmonic Nanoparticle Arrays

AbstractMetallic nanoparticles possess strong photothermal responses, especially when illuminated as ensembles due to collective effects. However, accurately quantifying the temperature increase remains a significant challenge, impeding progress in several applications. Anti Stokes thermometry offers a promising solution by enabling direct and non‐invasive temperature measurements of the metal without the need for labeling or prior calibration. While Anti Stokes thermometry is successfully applied to individual nanoparticles, its potential to study light‐to‐heat conversion with plasmonic ensembles remains unexplored. In this study, the theoretical framework and the conditions that must be fulfilled for applying Anti Stokes thermometry to ensembles of nanoparticles are discussed. Then, this technique is implemented to measure the light‐induced heating of square arrays of Au nanodisks. The obtained temperature measurements are validated using wavefront microscopy, demonstrating excellent agreement between the two thermometry methods. These results showcase the extension of Anti Stokes thermometry to plasmonic ensembles, highlighting its potential for implementation in the diverse photothermal applications involving these systems.

Nanoporous Titanium Oxynitride Nanotube Metamaterials with Deep Subwavelength Heat Dissipation for Perfect Solar Absorption.

We report a quasi-unitary broadband absorption over the ultraviolet-visible-near-infrared range in spaced high aspect ratio, nanoporous titanium oxynitride nanotubes, an ideal platform for several photothermal applications. We explain such an efficient light-heat conversion in terms of localized field distribution and heat dissipation within the nanopores, whose sparsity can be controlled during fabrication. The extremely large heat dissipation could not be explained in terms of effective medium theories, which are typically used to describe small geometrical features associated with relatively large optical structures. A fabrication-process-inspired numerical model was developed to describe a realistic space-dependent electric permittivity distribution within the nanotubes. The resulting abrupt optical discontinuities favor electromagnetic dissipation in the deep sub-wavelength domains generated and can explain the large broadband absorption measured in samples with different porosities. The potential application of porous titanium oxynitride nanotubes as solar absorbers was explored by photothermal experiments under moderately concentrated white light (1-12 Suns). These findings suggest potential interest in realizing solar-thermal devices based on such simple and scalable metamaterials.

Improving Lyophilization and Long-Term Stability of Gold Nanostars for Photothermal Applications

Improving Lyophilization and Long-Term Stability of Gold Nanostars for Photothermal Applications