Photothermal Method Research Articles

“Dandelion” magnetic bead-driven CDs@CeO2 based-multifunctional nanoplatform for tri-modal ultrasensitive detection and efficient eradication of pathogenic bacteria

To address the challenge of foodborne pathogens, we have developed an ultra-sensitive tri-modal detection and effective pathogen eradication strategy utilizing a “dandelion” magnetic bead-driven cerium dioxide doped with carbon dots (CDs@CeO2) multifunctional nanoplatform. Aptamer (Apt) modification CDs@CeO2 specifically recognizes and binds to the outer membrane proteins of Salmonella typhimurium (S. typhimurium). Concurrently, mannose-functionalized dandelion-like magnetic beads selectively recognize adhesins of S. typhimurium, avoiding competition with Apt for binding sites and leveraging the strong bacterial capture capability for high-sensitivity detection. The prepared CDs@CeO2 has been demonstrated to exhibit favourable fluorescence characteristics. In the presence of H2O2, CDs@CeO2 is capable of oxidising colourless 3,3',5,5'-tetramethylbenzidine (TMB) into blue oxide, displaying exceptional photothermal properties. CDs@CeO2 have the potential to generate •OH through a Fenton-like reaction, which could directly damage cells. Notably, coupling the photosensitizer Ce6 to CDs@CeO2 and subsequent illumination generates 1O2, which synergistically eradicates bacteria with •OH. Detection limits of the fluorescence, colorimetry, and photothermal methods were 3.85 cfu/mL, 9.44 cfu/mL, and 5.00 cfu/mL, respectively. The platform successfully achieves precise detection of S. typhimurium in actual pre-prepared food samples through fluorescence, colorimetry, and photothermal tri-modal signals, and effectively kills bacteria, achieving trace detection and source control.

Photothermal measurement of material properties for translucent thermal barrier coatings

In this study, a photothermal nondestructive method was proposed to measure the material parameters of semi-transparent or translucent thermal barrier coatings (TBCs). We derived a theoretical model for the photothermal signal from a two-layer semi-infinite material system with a translucent first layer after a pulse laser excitation. Its solution was verified by numerical solution. A data regression algorithm based on a least-squares fitting was used for the determination of the material parameters in the translucent first layer material. To verify this new method, an experimental system was set up with a pulse laser for thermal excitation and an infrared camera for image acquisition of the thermal emission transient from several translucent EBPVD TBC samples. The predicted coating thickness is consistent with the measured value by an optical microscope. The predicted thermal conductivity and optical attenuation coefficients in the absorption and emission band are found to be in good agreement with reference values.

Achieving ultrasensitive detection of glyphosate in fruits and vegetables using a triple-mode strategy based on carbon dots nanozymes derived from expired drugs

Rapid and sensitive detection of glyphosate (GLP) holds significant importance in the monitoring of environmental pollution and potential risks to human health. In this study, carbon dots nanozymes (CDszymes) with peroxidase-like activity were synthesized rapidly using a microwave-assisted method, employing expired drugs as raw materials. In the presence of H2O2, CDszymes catalyze the oxidation of TMB to generate blue oxTMB, which exhibits a photothermal effect under near-infrared light irradiation; an inner filter effect (IFE) may occur between oxTMB and CDszymes. By coupling the cascade catalysis of AChE and ChOx to generate H2O2, GLP effectively inhibits the activity of AChE, constructing a colorimetric/fluorescent/photothermal response platform for GLP. In colorimetry, the detection limit of GLP was 0.33 ng/mL. The detection limits of GLP by fluorescence method and photothermal method were 0.02 ng/mL and 0.41 ng/mL, respectively. The efficacy of this methodology has been successfully demonstrated in fruit and vegetable, it also provides a strategy for the high-value conversion of expired drugs.

Contactless thermal diffusivity characterization of second order magnetocaloric materials under magnetic field using modulated photo-thermal radiometry method with very low power probe beam

The thermal diffusivity of magnetocaloric materials has a transition point at a given temperature that depends on the intensity of the applied magnetic field. Consequently, a fine temperature resolution on the material sample is needed to obtain an accurate determination of the thermal diffusivity variation with temperature. The coupling between the external and the internal fields has to be carefully mastered since the pertinent operating condition is fixed by the actual internal field which is not directly measurable and may be heavily affected by any element in contact with the sample. Therefore, contactless methods such as Photo-Thermal Radiometry (PTR) are privileged. The latter is based on a radiative excitation of the front face of a thin sample and the detection of the thermal effect on the opposite face. However, the powerful radiative source may significantly increase the sample temperature which is not suitable for caloric materials. In this work, a low power modulated PTR method is proposed to characterize second order magnetocaloric materials under magnetic field. It was compared to high energy thermo-flash PTR and validated on common materials such as steel and stainless steel, and then applied to gadolinium which is the reference magnetocaloric material for magnetic refrigeration and heat pumping study. The thermal diffusivity of gadolinium samples is measured in the 285.1 K to 305.1 K temperature range, including the magnetic transition temperature without and under an external magnetic flux density of 0.5 T in the 13 mm air gap of the permanent magnet magnetic circuit. The low power probe beam ensures a temperature stability with a negligible sample temperature fluctuation less than 0.05 K on the incident sample surface and less than 0.03 K on the measurement surface. The experimental results without magnetic field align with those using other methods including the magnetic transition temperatures determination. This low-power optical method proved its efficiency to characterize highly temperature dependent materials such as magnetocaloric materials sensitive to magnetic field. The data obtained partly fills the lack of information in the literature on excited gadolinium.

Development of MnO2 nanosheets nanozyme-based colorimetric and photothermal dual-signal platform for monitoring alkaline phosphatase activity

Herein, a dual-signal biosensing platform for monitoring alkaline phosphatase (ALP) activity was developed. This platform combined the oxidase-mimicking activity of MnO2 nanosheets (NS) with the colorimetric and photothermal properties of oxidized 3,3′,5,5′-tetramethylbenzidine (oxTMB). MnO2 NS effectively catalyzed the oxidation of TMB to oxTMB, resulting in a color change from colorless to blue and a significant light absorption band at 652 nm. Meanwhile, oxTMB demonstrated pronounced photothermal properties, with the solution exhibiting a notable increase in temperature upon irradiation with an 808 nm laser. In the presence of ALP, 2-Phospho-L-ascorbic acid trisodium salt (AAP) was converted into L-ascorbic acid (L-AA), which then reacted with MnO2 NS. Consequently, MnO2 NS was inhibited from oxidizing TMB to oxTMB. Based on this principle, a dual-readout assay that integrated both colorimetric and photothermal signals for ALP detection was developed. The detection limits were 0.08 mU/mL for the colorimetric method and 0.12 mU/mL for the photothermal method. Furthermore, the platform was successfully applied to human serum samples, demonstrating its effectiveness in detecting ALP in complex biological matrices. The combination of colorimetric and photothermal responses enhanced both the accuracy and reliability of ALP detection, making this platform a promising tool for biomedical applications.

Multifunctional Photothermal Nanorods for Targeted Treatment of Drug-Resistant Bacteria-Induced Wound Healing.

The challenge of drug-resistant bacteria-induced wound healing in clinical and public healthcare settings is significant due to the negative impacts on surrounding tissues and difficulties in monitoring the healing progress. We developed photothermal antibacterial nanorods (AuNRs-PU) with the aim of selectively targeting and combating drug-resistant Pseudomonas aeruginosa (P. aeruginosa). The AuNRs-PU were engineered with a bacterial-specific targeting polypeptide (UBI29-41) and a bacterial adhesive carbohydrate polymer composed of galactose and phenylboronic acid. The objective was to facilitate sutureless wound closure by specially distinguishing between bacteria and nontarget cells and subsequently employing photothermal methods to eradicate the bacteria. AuNRs-PU demonstrated high photothermal conversion efficiency in 808 nm laser and effectively caused physical harm to drug-resistant P. aeruginosa. By integrating the multifunctional bacterial targeting copolymer onto AuNRs, AuNRs-PU showed rapid and efficient bacterial targeting and aggregation in the presence of bacteria and cells, consequently shielding cells from bacterial harm. In a diabetic rat wound model, AuNRs-PU played a crucial role in enhancing healing by markedly decreasing inflammation and expediting epidermis formation, collagen deposition, and neovascularization levels. Consequently, the multifunctional photothermal therapy shows promise in addressing the complexities associated with managing drug-resistant infected wound healing.

Photothermal Catalytic Removal of 1,2-DCE with High HCl Selectivity over the Brønsted Acid-Enriched Sulfur-Doped MOFs.

Chlorinated volatile organic compounds come from a wide range of sources and are highly toxic, posing a serious threat to biological health and the environment. Herein, a high-efficiency and energy-saving photothermal synergistic catalytic oxidation method was developed for the removal of 1,2-dichloroethane (1,2-DCE). Compared to traditional thermocatalysis, the 1,2-DCE conversion over Ru-U6S in photothermal synergistic catalysis at 340 °C increased by approximately 44% not only reducing energy consumption but also avoiding the instability of MOF structure caused by high reaction temperature. The excellent photothermal catalytic oxidation activity was derived from the synergistic effect of photo- and thermocatalysis. Ru-U6S demonstrated excellent 1,2-DCE adsorption capacity and stronger light utilization and could produce more reactive oxygen species (•OH and •O2-) after light illumination, which participated in the oxidation reaction, promoting the release of the active site of the catalyst. The results of H2O-TPD and NH3-DRIFTS exhibited that the use of S-containing ligands in the synthesis process increased the hydroxyl groups and Brønsted acid sites, significantly improved the selectivity of CO2 and HCl in the oxidation process, and reduced the release of chlorine-containing byproducts. This work provides a high-efficiency and energy-saving strategy for removing chlorinated volatile organic compounds and increasing the selectivity of ideal products directly with MOFs directly.

Photothermally Heated Asymmetric Thin Nanopores Suggest the Influence of Temperature on the Intermediate Conformational State of Cytochrome c in an Electric Field.

Nanopore sensing is a label-free single-molecule technique that enables the study of the dynamical structural properties of proteins. Here, we detect the translocation of cytochrome c (Cyt c) through an asymmetric thin nanopore with photothermal heating to evaluate the influence of temperature on Cyt c conformation during its translocation in an electric field. Before Cyt c translocates through an asymmetric thin SiNx nanopore, ∼1 ms trapping events occur due to electric field-induced denaturation. These trapping events were corroborated by a control analysis with a transmission electron microscopy-drilled pore and denaturant buffer. Cyt c translocation events exhibited markedly greater broad current blockade when the pores were photothermally heated. Collectively, our molecular dynamics simulation predicted that an increased temperature facilitates denaturation of the α-helical structure of Cyt c, resulting in greater blockade current during Cyt c trapping. Our photothermal heating method can be used to study the influence of temperature on protein conformation at the single-molecule level in a label-free manner.

Ultrasmall VOx nanoparticle as low-cost photothermal nanoprobe for enzyme-based biodetection

Low-cost photothermal probes facilitate the practical application of photothermal detection. However, current photothermal nanoprobes are generally larger in size and thus have slower reactivity with analytes, which is not conducive to rapid testing. Therefore, ultra-small photothermal nanoprobes would be preferred but have not been reported. Here, the ultrasmall VOx nanoparticle is constructed as low-cost photothermal nanoprobe, which is more reactive to H2O2 and thus has reduced response time. In cooperation with enzymes, this nanoprobe can be used for photothermal detection of other biomolecules, such as glucose and uric acid. Compare with the standard colorimetric method, the photothermal method with ultrasmall VOx nanoparticle has high similarity and low analytical error of less than 5 %, which is sufficient for actual practice.

Fabrication of superior laccase-mimicking enzyme with catalytic oxidative and photothermal properties for anti-bacterial and dual-mode glutathione S-transferase monitoring

A novel laccase mimic enzyme Cu–Mn with excellent photothermal properties was firstly prepared via a combination of hydrothermal and in situ synthesis. Cu–Mn nanozymes could catalyze the typical laccase substrate 2,4-dichlorophenol (2,4-DP) to generate the red quinone imine. Further, loading the MnO2 nanosheets with photothermal properties, Cu–Mn nanozymes possessed not only excellent laccase catalytic activity, but also high photothermal conversion efficiency. The presence of glutathione S-transferase (GST) recovered the glutathione (GSH)-induced weakness of the laccase activity and photothermal properties of Cu–Mn. Hence, a GST enzyme-regulated dual-mode sensing strategy was established based on Cu–Mn nanozymes. The detection limits of GST monitoring based on colorimetric and photothermal methods were 0.092 and 0.087 U/L with response times of 20 min and 8 min, respectively. Furthermore, the proposed method enabled the measuring of GST levels in human serum and was successfully employed in the primary evaluation of hepatitis patients. Another attraction, the impressive photothermal behavior also endowed the Cu–Mn nanozymes with promising antimicrobial properties, which exhibited significant antimicrobial effects against Escherichia coli (E.coli) and Staphylococcus aureus (S.aureus). Unsurprisingly, multifunctional Cu–Mn nanozymes certainly explore new paths in biochemical analysis and antimicrobial applications.

Multifunctional 2D hemin-bridged MOF for the efficient removal and dual-mode detection of organophosphorus pesticides.

The high-residual and bioaccumulation property of organophosphorus pesticides (OPs) creates enormous risks towards the ecological environment and human health, promoting the research for smart adsorbents and detection methods. Herein, 2D hemin-bridged MOF nanozyme (2D-ZHM) was fabricated and applied tothe efficient removal and ultrasensitive dual-mode aptasensing of OPs. On the one hand, the prepared 2D-ZHM contained Zr-OH groups with high affinity for phosphate groups, endowing it with selective recognition and high adsorption capacity for OPs (285.7mgg-1 for glyphosate). On the other hand, the enhanced peroxidase-mimicking biocatalytic property of 2D-ZHM allowed rapid H2O2-directed transformation of 3,3',5,5'-tetramethylbenzidine to oxidic product, producing detectable colorimetric or photothermal signals. Using aptamers of specific recognition capacity, the rapid quantification of two typical OPs, glyphosate and omethoate, was realized with remarkable sensitivity and selectivity. The limit of detections (LODs) of glyphosate were 0.004nM and 0.02nM for colorimetric and photothermal methods, respectively, and the LODs of omethoate were 0.005nM and 0.04nM for colorimetric and photothermal methods, respectively. Theconstructed dual-mode aptasensing platform exhibited outstanding performance for monitoring OPs in water and fruit samples. This work provides a novel pathway to develop MOF-based artificial peroxidase and integrated platform for pollutant removal and multi-mode aptasensing.

Rapid quantitative PCR equipment using photothermal conversion of Au nanoshell

The emergence of infectious diseases worldwide necessitates rapid and precise diagnostics. Using gold nanoshells in the PCR mix, we harnessed their unique photothermal properties in the near-infrared regime to attain efficient heating, reaching ideal photothermal PCR cycle temperature profile. Our photothermal PCR method expedited DNA amplification while retaining its detection sensitivity. Combining photothermal quantitative PCR with real-time fluorometry and non-invasive temperature measurement, we could amplify the target DNA within just 25 min, with a minimum detectable DNA amount of 50 picograms. This innovation in photothermal qPCR, leveraging the photothermal properties of gold nanoshells, will pave the way for immediate point-of-care diagnostics of nucleic acid biomarkers.

Application of photothermal effects of nanomaterials in food safety detection.

Numerous nanomaterials endowed with outstanding light harvesting and photothermal conversion abilities have been extensively applied in various fields, such as photothermal diagnosis and therapy, trace substance detection, and optical imaging. Although photothermal detection methods have been established utilizing the photothermal effect of nanomaterials in recent years, there is a scarcity of reviews regarding their application in food safety detection. Herein, the recent advancements in the photothermal conversion mechanism, photothermal conversion efficiency calculation, and preparation method of photothermal nanomaterials were reviewed. In particular, the application of photothermal nanomaterials in various food hazard analyses and the newly established photothermal detection methods were comprehensively discussed. Moreover, the development and promising future trends of photothermal nanomaterial-based detection methods were discussed, which provide a reference for researchers to propose more effective, sensitive, and accurate detection methods.

A colorimetric and photothermal dual-mode immunobiosensor for chloramphenicol based on the β-NiOOH nanozyme-3,3′,5,5′-tetramethylbenzidine system

A colorimetric and photothermal dual-mode detection method based on β-NiOOH nanozyme-3,3′,5,5′-tetramethylbenzidine system was established for chloramphenicol content in fruit juice.

4D Printed Protein‐AuNR Nanocomposites with Photothermal Shape Recovery

Abstract4D printing is the 3D printing of objects that change chemically or physically in response to an external stimulus over time. Photothermally responsive shape memory materials are attractive for their ability to undergo remote activation. While photothermal methods using gold nanorods (AuNRs) are used for shape recovery, 3D patterning of these materials into objects with complex geometries using degradable materials is not addressed. Here, the fabrication of 3D printed shape memory bioplastics with photo‐activated shape recovery is reported. Protein‐based nanocomposites based on bovine serum albumin (BSA), poly (ethylene glycol) diacrylate (PEGDA), and AuNRs are developed for vat photopolymerization. These 3D printed bioplastics are mechanically deformed under high loads, and the proteins served as mechano‐active elements that unfolded in an energy‐dissipating mechanism that prevented fracture of the thermoset. The bioplastic object maintained its metastable shape‐programmed state under ambient conditions. Subsequently, up to 99% shape recovery is achieved within 1 min of irradiation with near‐infrared (NIR) light. Mechanical characterization and small angle X‐ray scattering (SAXS) analysis suggest that the proteins mechanically unfold during the shape programming step and may refold during shape recovery. These composites are promising materials for the fabrication of biodegradable shape‐morphing devices for robotics and medicine.

Photothermal radiometry using normalized DC component for coating thickness evaluation

An improved photothermal technique for evaluating opaque coating thicknesses using a normalized DC component is proposed. The pump beam is modulated at a frequency that the generated thermal wave only exists in the coating layer and becomes invariant to the thickness changes. The DC component is normalized by the amplitude of the AC signal in order to eliminate the dependency on the pump intensity, surface absorptivity, and emissivity. Both theoretical analysis and experimental results demonstrate that the normalized DC component is linearly correlated to the coating thickness over a broad range. This method offers a significant advantage over existing photothermal methods by avoiding the tedious procedure of frequency trails for coatings of an unknown thickness. Also, the non-monotonic issue is successfully resolved.

Colorimetric and photothermal dual-mode aptasensor with redox cycling amplification for the detection of ochratoxin A in corn samples

Ochratoxin A (OTA) detection is critical for public health safety. This study proposes a G-quadruplex-Hemin/iodide (G4-Hemin/I−)-mediated non-enzyme redox cycling amplification (RCA) system for dual-modal (colorimetric and photothermal thermometer) OTA analysis. The proposed aptasensor platform for point-of-care testing employs a common thermometer for quantitative signal readouts. The OTA aptamer folds into a G4 structure, which significantly enhances the catalytic activity in the presence of I− after RCA reaction. Moreover, a notable temperature enhancement causes color changes, providing an ultrasensitive and label-free platform for OTA detection. Further, the designed sensor was applied to OTA content determination in corn samples and achieved satisfactory results compared to a commercial enzyme-linked immunoassay kit. The proposed dual-mode aptasensor is simple, highly sensitive (1 pg/mL for colorimetric method, 0.8 pg/mL for photothermal method), selective, and suitable for low-cost instrument-free bioanalysis in low-resource settings.

Multifunctional magnetic composite nanomaterial for Colorimetric-SERS Dual-Mode detection and photothermal sterilization of Vibrio parahaemolyticus

In this study, a colorimetric and SERS dual-mode detection and photothermal sterilization method targeting Vibrio parahaemolyticus (V. parahaemolyticus) was proposed by preparing a multifunctional composite magnetic material (Fe3O4@MOF(Fe-Cu)-GNS-MBA-Apt) and integrating it with magnetophoretic chromatography technology. The composite magnetic material modified with aptamer demonstrated specific capture of V. parahaemolyticus in food matrices through magnetic separation. The dual-mode quantitative detection of V. parahaemolyticus was achieved by combining magnetophoretic chromatography for the separation of free materials and bacteria-material complexes and the peroxidase-like activity and SERS effect of the composite material. Under optimized conditions, the dual-mode sensor exhibited detection limits of 9 cfu·mL−1 (101 ––105 cfu·mL−1) in the colorimetric modality and 7 cfu·mL−1 (101 ––105 cfu·mL−1) in the SERS modality. Furthermore, the photothermal properties of the material allowed for the sterilization of bacteria in the detection solution within 4 min of near-infrared irradiation. Moreover, the developed method, based on the multifunctional materials, characterized by its rapid, sensitive, and efficient, was successfully applied to fresh shrimp samples, thus validating its potential for rapid pathogen diagnosis and contributing to the establishment of a safety control system of food and environmental detection process.

Photothermally heated colloidal synthesis of nanoparticles driven by silica-encapsulated plasmonic heat sources

Using photons to drive chemical reactions has become an increasingly important field of chemistry. Plasmonic materials can provide a means to introduce the energy necessary for nucleation and growth of nanoparticles by efficiently converting visible and infrared light to heat. Moreover, the formation of crystalline nanoparticles has yet to be included in the extensive list of plasmonic photothermal processes. Herein, we establish a light-assisted colloidal synthesis of iron oxide, silver, and palladium nanoparticles by utilizing silica-encapsulated gold bipyramids as plasmonic heat sources. Our work shows that the silica surface chemistry and localized thermal hotspot generated by the plasmonic nanoparticles play crucial roles in the formation mechanism, enabling nucleation and growth at temperatures considerably lower than conventional heating. Additionally, the photothermal method is extended to anisotropic geometries and can be applied to obtain intricate assemblies inaccessible otherwise. This study enables photothermally heated nanoparticle synthesis in solution through the plasmonic effect and demonstrates the potential of this methodology.

Mechanically Robust Interface at Metal/Muscovite Quasi van der Waals Epitaxy.

Quasi van der Waals epitaxy is an approach to constructing the combination of 2D and 3D materials. Here, we quantify and discuss the 2D/3D interface structure and the corresponding features in metal/muscovite systems. High-resolution scanning transmission electron microscopy reveals the atomic arrangement at the interface. The theoretical results explain the formation mechanism and predict the mechanical robustness of these metal/muscovite quasi van der Waals epitaxies. The evidence of superior interface quality is delivered according to the outstanding performance of the designed systems in both retention (>105 s) and cycling tests (>105 cycles) through electromechanical measurements. With high-temperature X-ray reciprocal space mapping, the unique anisotropy of thermal expansion is discovered and predicted to sustain the thermal stress with a sizable thermal actuation. A maximum bending curvature of 264 m-1 at 243 °C can be obtained in the silver/muscovite heteroepitaxy. The electrothermal and photothermal methods show a fast response to thermal stress and demonstrate the interface robustness.