Photothermal System Research Articles

Construction of a photothermal controlled-release microcapsule pesticide delivery system

This study aimed to achieve the controlled-release of bioactive ingredients in microcapsule pesticide delivery systems. A photothermal controlled-release microcapsule pesticide delivery system was constructed using chitosan and polydopamine (PDA) as the wall materials to encapsulate avermectin. All the prepared microcapsules were characterized by the methods of optical microscopy, scanning electron microscopy, transmission electron microscopy, and Fourier-transform infrared spectroscopy. The slow-release, UV-shielding, photothermal performance, and the nematicidal activity of the prepared microcapsules were also systematically investigated. The results indicated that the prepared microcapsules had excellent slow-release and UV-shielding performance when further encapsulated with the PDA layer relative to those of the non-PDA-encapsulated products. The photothermal sensitivity of the AVM@CS/CMA/PDA composite microcapsule under the irradiation of near-infrared light (NIR) was dramatically enhanced with the photothermal conversion efficiency (η) of 14.93%. Furthermore, the nematicidal activity of the AVM@CS/CMA/PDA composite microcapsule system was effectively improved on exposure to the irradiation of a light-emitting diode (LED) full-spectrum light. The strategies used in this study for developing the photothermal controlled-release pesticide delivery system might play an important role on improving utilization of pesticides.

An azobenzene-based photothermal energy storage system for co-harvesting photon energy and low-grade ambient heat via a photoinduced crystal-to-liquid transition

Ambient heat, slightly above or at room temperature, is a ubiquitous and inexhaustible energy source that has typically been ignored due to difficulties in its utilization. Recent evidence suggests that a class of azobenzene (Azo) photoswitches featuring a reversible photoinduced crystal-to-liquid transition could co-harvest photon energy and ambient heat. Thus, a new horizon has been opened for recovering and regenerating low-grade ambient heat. Here, a series of unilateral para-functionalized photoinduced liquefiable Azo derivatives is presented that can co-harvest and convert photon energy and ambient heat into chemical bond energy and latent heat in molecules and eventually release them in the form of high-temperature utilizable heat. A straightforward crystalline-to-liquid phase transition achieved with ultraviolet light irradiation (365 nm) is enabled by appending a halogen/alkoxy group on the para-position of the Azo photoswitches, and the release of thermal energy is triggered by short-wavelength visible-light irradiation (420 nm). The phase transition properties of the trans- and cis-isomers and the energy density, storage lifetime and heat release performance of the cis-liquid are investigated with differential scanning calorimetry, ultraviolet-visible absorption spectroscopy, and an infrared (IR) thermal camera. The experimental results indicate a high energy density of 335 J/g, a long lifetime of 5 d and a heat release of up to 6.3 °C due to the coupled photochemical-thermophysical mechanism. This work presents a new model for utilizing renewable energy, i.e., the photoinduced conversion of ambient thermal energy.

A Flexible and Highly Efficient Graphene-Based Photothermal Evaporation Device with Independent Water Transport and Photothermal Absorption System

A Flexible and Highly Efficient Graphene-Based Photothermal Evaporation Device with Independent Water Transport and Photothermal Absorption System

A photothermal system for wastewater disposal and co-generation of clean water and electricity

Since energy crisis and water shortage become critical issues in increasingly industrialized society, solar-assisted water disposal technologies remain a great challenge. This work investigated solar-driven photothermal disposal of wastewater for simultaneous production of clean water and electricity. This strategy relies on an integrated photothermal and photoelectric film composed of Ag/TiO2 nanoparticles grafted on the surface of carbon nanotubes (CNTs) coated with nickel foam (NF) substrate (Ag/TiO2@CNTs@NF). The long-wavelength portion in the solar spectrum was employed for high-quality freshwater generation via solar-driven interfacial evaporation (water evaporation rate at 1.48 kg m−2 h−1), with a solar-to-water evaporation efficiency of ~96%. The short-wavelength bands were adsorbed for the simultaneous solar-driven oxidation of organic pollutants (oxidation efficiency to methylene blue of ~94.2%) and the generation of electricity (photocurrent of ~228 μA cm−2). Therefore, this integrated system can dispose wastewater while achieve pure water and electricity with high utilization efficiency for solar energy.

Poly(N-phenylglycine)/MoS2 Nanohybrid with Synergistic Solar-Thermal Conversion for Efficient Water Purification and Thermoelectric Power Generation.

Solar interfacial evaporation is an emerging technology in solar energy harvesting developed to remedy the global energy crisis and the lack of freshwater resources. However, developing fully enhanced thermal management to optimize solar-heat utilization efficiency and form remains a great challenge. We created a synergistic photothermal layer from a poly(N-phenylglycine) (PNPG)/MoS2 nanohybrid via electrostatic-induced self-assembly for a broad-spectrum and efficient solar absorption. The PNPG/MoS2 system provided effective synergistic photothermal conversion and good water transmission, enabling rapid solar steam escape. Notably, synergistic coupling of solar evaporation-thermoelectric (TE) power generation was also achieved, providing more efficient exploitation of solar heat. The system demonstrated a solar evaporation rate of up to 1.70 kg m-2 h-1 and achieved a maximum thermoelectric output power with 0.23 W m-2 under one sun. The high-performance PNPG/MoS2 synergistic photothermal system developed in this study offers potential opportunities for coupling solar water purification with thermoelectric power generation to meet the needs of resource-scarce areas.

Photothermal air gap membrane distillation for the removal of heavy metal ions from wastewater

As the world population grows, pure water becomes increasingly scarce, making wastewater treatment necessary. However, the processes currently used to treat industrial wastewater are generally energy-intensive, highlighting the need to develop environmentally friendly wastewater treatment technologies. To address this issue, a photothermal air–gap membrane distillation system was developed and tested for the first time to remove heavy metal ions from wastewater. Activated carbon particles at different concentrations were used in the prepared polyvinylidene fluoride membranes as components for solar energy recovery. Zinc, one of the most common heavy metals in industrial wastewater in the United Arab Emirates, was used as a model contaminant in this study. The results showed that the use of Activated Carbon particles to modify Polyvinylidene fluoride membranes can significantly improve solar absorption (97%) and porosity (60.6%), resulting in a permeate flux of 0.32 L/m2h and a rejection of 97% of Zn ions. Additionally, the optimized membrane was tested using a synthetic heavy metal solution and showed high rejection rates for most of the tested heavy metals (Zn2+, Fe3+, Cu2+, Cr3+, and Ni2+), which can be potentially used in the industrial heavy metal removal process. The developed photothermal water treatment system can provide a highly efficient and scalable water treatment process.

A 3D C@TiO2 multishell nanoframe for simultaneous photothermal catalytic hydrogen generation and organic pollutant degradation

Rapid heat loss and fast charge carrier recombination constitute two crucial issues that hinder the development of efficient solar energy utilization and conversion over the semiconductor in a photothermal catalytic system. Inspired by energy production from waste water, we designed an advanced 3D C@TiO2 multishell nanoframe (MNF) photocatalyst. Its unique structural features of heat confinement and vibrant photocarrier kinetics lead to excellent photo-thermal conversion for synchronous superior photocatalytic H2 evolution (503 μmol g-1h−1) and 98.2% RhB removal without the use of any co-catalyst and sacrificial reagent under simulated sunlight irradiation (AM 1.5G). Mechanism exploration reveals that the difference between the inner and outer gas pressure formed inside C@TiO2 precursor facilitates the selective cleavage of outer TiO2 layers at selected temperatures during calcination. Synergistic effects between residual carbon core and multi-shelled TiO2 framework endow C@TiO2 MNF with excellent heat confinement and vibrant photocarrier kinetics. Such MNF photo-thermocatalyst concept provides a novel strategy for effective utilization of solar energy, and this work may open a novel avenue towards advanced nanostructures for efficient waste-to-energy conversion.

Novel Photothermal Aptamer-based Sensing System for Highly Ultrasensitive Detection of Ochratoxin A

Novel Photothermal Aptamer-based Sensing System for Highly Ultrasensitive Detection of Ochratoxin A

Functionalized MoS2 Nanoflowers with Excellent Near-Infrared Photothermal Activities for Scavenging of Antibiotic Resistant Bacteria.

Presently, antibiotic resistant bacteria (ARB) have been commonly found in environment, such as air, soil and lakes. Therefore, it is urgent and necessary to prepare antimicrobial agents with excellent anti-antibiotic resistant bacteria. In our research, poly-ethylene glycol functionalized molybdenum disulfide nanoflowers (PEG-MoS2 NFs) were synthesized via a one-step hydrothermal method. As-prepared PEG-MoS2 NFs displayed excellent photothermal conversion efficiency (30.6%) and photothermal stability. Under 808 nm NIR laser irradiation for 10 min, the inhibition rate of tetracycline-resistant Bacillus tropicalis and Stenotrophomonas malphilia reached more than 95% at the concentration of 50 μg/mL. More interestingly, the photothermal effect of PEG-MoS2 NFs could accelerate the oxidation of glutathione, resulting in the rapid death of bacteria. A functionalized PEG-MoS2 NFs photothermal anti-antibiotic resistant system was constructed successfully.

Solar Desalination via Multilayers of Transparent Photothermal Fe3O4@Cu2–xS Thin Films

In contrast to a conventional single layer solar still, herein a multilayer system for solar light harvesting and water evaporation via transparent photothermal thin films is developed. Monodispersed Fe3O4@Cu2–xS nanoparticles are dispersed in a polymer solution and deposited on glass and quartz substrates as transparent thin films. These thin films are optically characterized with strong absorptions in the UV and NIR regions, and high average visible transmittance. The photon energies in the UV/NIR regions are converted to heat increasing the water evaporation rate, while the film high transparency makes it possible for light to pass through many layers for an enlarged solar harvesting surface area. A multilayer photothermal evaporation system (MPTES) is developed for water evaporation experiments using various photothermal films. Water evaporation rates are compared between Fe3O4@Cu2–xS and Fe3O4 against different numbers of layers in the MPTES. The photothermal and optical properties of Fe3O4@Cu2–xS thin films are correlated to the heating behaviors and saltwater evaporation rate. Due to high transparency and strong photothermal effects of the films, water evaporation is significantly enhanced via multilayers. The concept of the multilayer solar still will show promise in water desalination.

A sensitive photothermometric biosensor based on redox reaction-controlled nanoprobe conversion from Prussian blue to Prussian white.

As a new low-cost photothermal nanoprobe, Prussian blue nanoparticles (PB NPs) have been demonstrated to have more potential in photothermometric-based point-of-care testing (POCT) application. However, most of the existing PB NP-based photothermometric sensors were constructed mainly relying on in situ generation of PB NPs or their combination with antigens and antibodies, therefore usually suffering from the inherent defects like complicated preparation and cumbersome surface process as well as high-cost modification. To break this limitation of PB NP-based photothermometric POCT, we proposed an ingenious redox reaction-controlled nanoprobe conversion strategy and successfully applied to photothermometric detection of ascorbate oxidase (AAO). In this design, the heat of PB NP photothermal system under 808-nm laser irradiation dramatically decreased with the addition of AA, due to a unique AA-induced Prussian blue to Prussian white (PB-to-PW) conversion. Upon AAO addition, the heat of reaction system increased because of the enzymatic catalytic reaction between AAO and AA, which led to a significant reduction of AA and resultantly inhibited PB-to-PW conversion. Such target-mediated nanoprobe conversion resulted in an obvious temperature change that could be easily detected by a common thermometer and exhibited good linear ranges from 0.25 to 14mU/mL with a detection limit as low as 0.21mU/mL for POCT analysis of AAO. This facile, convenient, and portable photothermometric sensing platform provides an innovative route for the design of PB NP nanoprobe-based photothermometric detection methods. A sensitive photothermometric AAO sensor based on a redox reaction-controlled nanoprobe conversion strategy from Prussian blue to Prussian white.

A facile photothermometric sensor of acid phosphatase based on CoOOH nanozymes-mediated 3,3′,5,5′-tetramethylbenzidine photothermal system

Nanozymes-catalyzed 3,3′,5,5′-tetramethylbenzidine (TMB) reaction systems have been extensively used for fabricating colorimetric sensors, but they still require advanced instruments like color analysis software or ultraviolet spectrophotometers to achieve accurate quantitative analysis. Herein, we explored an alternative strategy to convert a color readout to a temperature readout of a CoOOH nanoflakes-TMB colorimetric reaction system, and successfully fabricated a simple and facile photothermometric sensor of acid phosphatase (ACP) by using a common thermometer as the reader. It mainly performed based on the strong photothermal effect of the oxidation product (TMBox) of TMB upon an 808 nm near-infrared (NIR) laser irradiation, which showed a close relationship with the ACP content with a lower limit of detection (LOD) of 0.037 mU/mL for photothermometric ACP determination. This photothermometric method was proved to be suitable for not only sensing ACP but also screening its inhibitor in human serum, and providing a simple, rapid, convenient, low cost, and portable organic chromogenic substrate-based sensing platform.

Effect of Cr2O3 on structural and magnetic properties of SiO2–B2O3–Fe2O3–Al2O3–Na2O glass–ceramics

SiO2–B2O3–Fe2O3 magnetic glass–ceramics were prepared by conventional melt quench using a heat treatment method. The effects of Cr2O3 on the phase structure and magnetic properties of the ferrimagnetic glass–ceramics were examined by differential scanning calorimetry, photothermal measurement system, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. The magnetic phase of the obtained glass–ceramics was Fe3O4, and the magnetic crystal size and amount of second phase (hematite, Fe2O3) increased with increasing amount of Cr2O3 added. More importantly, the coercivity and saturation magnetization of the sample without Cr2O3 were higher than the samples containing 1–4 wt.% Cr2O3, indicating the spontaneous crystallization capacity of magnetite.

Unidirectionally Driving Nanofluidic Transportation via an Asymmetric Textile Pump for Simultaneous Salt-Resistant Solar Desalination and Drenching-Induced Power Generation

Solar-driven seawater desalination provides a promising technology for sustainable water energy harvesting. Although tremendous efforts have been dedicated to developing efficient evaporators, the challenge of preventing salt accumulation while simultaneously realizing high-performance steam-electricity cogeneration remains to be addressed. In this work, inspired by the water and solute transportation in plants via the wicking mechanism, a one-way asymmetric nanofluidic photothermal evaporator fabricated by disproportionately depositing photothermal MXene nanosheets on a hydrophilic cotton textile is reported for simultaneous freshwater and power production. By unidirectionally driving dynamic saline transportation via this photothermal cotton textile pump, this evaporator not only enables self-operating salt rejection for stable steam generation but also affords continuous electric power generation induced by the formation of an asymmetric double electrode layer within MXene nanochannels under the drenching state. Specifically, the solar-driven evaporation rate and voltage generation reach 1.38 kg/m2/h (with a conversion efficiency of 83.1%) and 363 mV under 1 sun irradiation, respectively. Notably, this designed nanofluidic system suffers negligible performance depreciation after 30 h of operation and washing 15 times, which indicates its outstanding stability and reusability. This facile design of the asymmetric nanofluidic photothermal system may provide prospective opportunities for scaling up sustainable freshwater and electric power production.

Selective thermotherapy of tumor by self-regulating photothermal conversion system

One major challenge of photothermal therapy (PTT) is achieving thermal ablation of the tumor without damaging the normal cells and tissues. Here, we designed a self-regulating photothermal conversion system for selective thermotherapy based on self-assembling gold nanoparticles (S-AuNPs) and investigated the selectivity effect using a novel home-made in vitro selective photothermal transformation model and an in vivo skin damaging assessment model. In the in vitro selective photothermal transformation model, laser irradiation selectively increased the temperature of the internal microenvironment (pH 5.5) and resulted in an obvious temperature difference (ΔT ≥ 5 °C) with that of the external environment (pH 7.4). More importantly, in the in vivo skin damaging assessment model, S-AuNPs achieved good tumor inhibition without damaging the normal skin tissue compared with the conventional photothermal material. This work provides not only a novel validation protocol for tumor thermotherapy to achieve the biosafety of specifically killing tumor cells and normal tissue but also an evaluation methodology for other precise therapy for cancers.

Stimuli-responsive Ca-alginate-based photothermal system with enhanced foliar adhesion for controlled pesticide release

For minimizing volatilization and leaching of pesticides, and enhancing their residence time on crop surfaces, we synthesized and characterized a novel intelligent pesticide delivery system. Therein, imidacloprid (IMI) was adsorbed by polydopamine modified kaolin (PK) with high adsorption property through hydrogen bonds. Ca-alginate was used as a structural matrix of the system and a protective shell to hinder the pesticide burst release from PK, and endowed the system with unique pH-sensitive property for IMI release. The amino silicone oil (ASO) coating could bind with the waxy layer of crop leaves by the theory of “similarity-intermiscibility”, which increased the adhesion of composite on crop leaves. Moreover, by the excellent light-sensitive property of detonation nanodiamond (DND) and temperature-responsive performance of poly(N-isopropylacrylamide) (PNIPAm), the release of IMI from the functional system could be adjusted by sunlight. Besides, the composite displayed high control efficacy. This novel composite can promote the targeting ability and utilization efficiency of pesticides, thus having a huge potential application prospect in agriculture.

Oxidation efficiency and reaction mechanisms of gaseous elemental mercury by using CeO2/TiO2 and CuO/TiO2 photo-oxidation catalysts at low temperatures in multi-pollutant environments

• The catalytic oxidation efficiency of Hg 0 at low temperatures in multi-pollutant environments was investigated. • The oxidation efficiency of Hg 0 over 5%CuO/TiO 2 was obviously higher than that over 7%CeO 2 /TiO 2 . • In the atmosphere of N 2 +Hg 0 +SO 2 , SO 2 competed with Hg° for the active sites and thus inhibited the oxidation efficiency of Hg 0 . • 5%CuO/TiO 2 had better sulfur resistance than 7%CeO 2 /TiO 2 mainly due to strong interaction of Cu and Ti. Background :This study aimed to establish novel photothermal catalysts suitable for the reaction at temperatures of 100-200 ℃ to develop an innovative Hg0 and NO simultaneous removal technology in a lower temperature environment. To further explore the stability and sulfur resistance of 7%CeO 2 /TiO 2 and 5%CuO/TiO 2 , the oxidation efficiency and reaction mechanisms of Hg 0 were investigated in multi-pollutant environments at low temperatures. Methods: TiO 2 , CeO 2 /TiO 2 , and CuO/TiO 2 used to oxidize Hg 0 at low temperatures were prepared by the sol-gel method, which were localized to glass beads for each test. A self-designed photothermal catalytic reaction system consisted of a mercury generator, a mixing chamber, a catalytical reactor, and an m on-line mercury measuring instrument. Significant Findings: The oxidation efficiencies of Hg 0 for different reaction temperatures were ordered as η 100℃ >η 150℃ >η 200℃ in the atmosphere of N 2 +Hg 0 . In the atmosphere of N 2 +Hg 0 +NO, low concentration of NO (<300 ppm) exhibited inhibitive effect to Hg 0 oxidation, while high concentration of NO (>300 ppm) enhanced Hg 0 oxidation. In the atmosphere of N 2 +Hg 0 +SO 2 , SO 2 could occupy the active sites for Hg 0 oxidation and inhibited the oxidation of Hg 0 .

LED control of gene expression in a nanobiosystem composed of metallic nanoparticles and a genetically modified E. coli strain

BackgroundWithin the last decade, genetic engineering and synthetic biology have revolutionized society´s ability to mass-produce complex biological products within genetically-modified microorganisms containing elegantly designed genetic circuitry. However, many challenges still exist in developing bioproduction processes involving genetically modified microorganisms with complex or multiple gene circuits. These challenges include the development of external gene expression regulation methods with the following characteristics: spatial–temporal control and scalability, while inducing minimal permanent or irreversible system-wide conditions. Different stimuli have been used to control gene expression and mitigate these challenges, and they can be characterized by the effect they produce in the culture media conditions. Invasive stimuli that cause permanent, irreversible changes (pH and chemical inducers), non-invasive stimuli that cause partially reversible changes (temperature), and non-invasive stimuli that cause reversible changes in the media conditions (ultrasound, magnetic fields, and light).MethodsOpto-control of gene expression is a non-invasive external trigger that complies with most of the desired characteristics of an external control system. However, the disadvantage relies on the design of the biological photoreceptors and the necessity to design them to respond to a different wavelength for every bioprocess needed to be controlled or regulated in the microorganism. Therefore, this work proposes using biocompatible metallic nanoparticles as external controllers of gene expression, based on their ability to convert light into heat and the capacity of nanotechnology to easily design a wide array of nanostructures capable of absorbing light at different wavelengths and inducing plasmonic photothermal heating.ResultsHere, we designed a nanobiosystem that can be opto-thermally triggered using LED light. The nanobiosystem is composed of biocompatible gold nanoparticles and a genetically modified E. coli with a plasmid that allows mCherry fluorescent protein production at 37 °C in response to an RNA thermometer.ConclusionsThe LED-triggered photothermal protein production system here designed offers a new, cheaper, scalable switchable method, non-destructive for living organisms, and contribute toward the evolution of bioprocess production systems.

Photothermally Activated Coacervate Model Protocells as Signal Transducers Endow Mammalian Cells with Light Sensitivity.

The development of a novel photothermally activated coacervate model protocell is reported as a signal transducer to endow mammalian cells with light sensitivity. In this system, near-infrared light irradiation triggers H2 S release in coacervate model protocells, leading to modulation of the behavior of living cells. The functional coacervate model protocells are prepared by loading metal-alloyed plasmonic nanoparticles and an H2 S donor into the liquid coacervate microdroplets. Upon light irradiation, the H2 S signal messenger is released through the photothermal effect of plasmonic nanoparticles and photothermal mediated pyrolysis of the H2 S donor. The H2 S signal is delivered to the mammalian cell community to trigger depletion of reactive oxygen species, reduce the activity of lactate dehydrogenase and improve cell viability. This study provides a new approach to the implementation of chemical signaling in artificial cell colonies and protocell/living cell consortia. The photothermal protocell system offers a powerful platform for light modulation of the behavior of mammalian cells and shows great promise for biomedical applications.

Composite hydrogel-based photothermal self-pumping system with salt and bacteria resistance for super-efficient solar-powered water evaporation

Synergistically increasing the solar adsorption/conversion, regulating the water transfer and activation as well as resisting the fouling to enhance the solar-powered interfacial water evaporation performance remains an urgent challenge. Herein, a smart 3D porous photothermal composite hydrogel MoS2@GH, where the antibacterial porous molybdenum disulfide (MoS2) nanoflowers were intercalated between graphene (MoS2@GH) via a simple chemical reduction, was prepared. This cooperated with a controllable self-pumping system of salt concentration differences and liquid level height differences-driven capillary water transfer/transpiration (CHTS) for solar steam generator. In this generator, the hierarchically porous hydrogel not only contributed the light trapping to enhance solar absorption but also generated more dispersed hotspots to access and activate water. Simultaneously, the CHTS system regulated an appropriate water replenishment without direct immersion into bulk water to match the evaporation of hydrogel. As a result, this system can achieve a super-efficient water evaporation rate of 3.2 kg m−2 h−1 under 0.9 sun, and can also delay the salting out fouling and resist the bacterial biofouling. These together with the good thermal and chemical stability of the pure inorganic hydrogel entrust an efficient water desalination, paving a robust way for sustainable clean water production.