Photothermal Probe Research Articles

Click-free imaging of carbohydrate trafficking in live cells using an azido photothermal probe.

Real-time tracking of intracellular carbohydrates remains challenging. While click chemistry allows bio-orthogonal tagging with fluorescent probes, the reaction permanently alters the target molecule and only allows a single snapshot. Here, we demonstrate click-free mid-infrared photothermal (MIP) imaging of azide-tagged carbohydrates in live cells. Leveraging the micromolar detection sensitivity for 6-azido-trehalose (TreAz) and the 300-nm spatial resolution of MIP imaging, the trehalose recycling pathway in single mycobacteria, from cytoplasmic uptake to membrane localization, is directly visualized. A peak shift of azide in MIP spectrum further uncovers interactions between TreAz and intracellular protein. MIP mapping of unreacted azide after click reaction reveals click chemistry heterogeneity within a bacterium. Broader applications of azido photothermal probes to visualize the initial steps of the Leloir pathway in yeasts and the newly synthesized glycans in mammalian cells are demonstrated.

A novel fluorescent and photothermal probe based on nanozyme-mediated cascade reaction for detecting organophosphorus pesticide residues

In this study, a nanozyme (ZIF-Co-Cys) with high oxidase-like catalytic activity was prepared, and a ratiometric fluorescent/photothermal dual-mode probe was constructed for organophosphorus pesticides (OPs) detection based on the competitive effect of ZIF-Co-Cys and the enzymatic reaction product of acid phosphatase (ACP) on o-phenylenediamine and the inhibition effect of OPs on ACP activity. Using dimethyl dichloroviny phosphate (DDVP) as the model, both the fluorescence intensity ratio and the temperature change of the probe solution exhibited an excellent correlation with OPs concentration. The detection limits were 1.64 ng/mL and 0.084 ng/mL, respectively. Additionally, the detection of DDVP residues in real samples verified the outstanding anti-interference and accuracy of the probe. This work not only provided a complementary dual-mode method for the accurate and rapid detection of OPs residues in complex samples, but also supplied a new insight into the design of a multi-mode sensing platform based on the cascade reaction of nanozyme.

Hyperthermia/glutathione-triggered ferritin nanoparticles amplify the ferroptosis for synergistic tumor therapy

Breast cancer is the most diagnosed malignancy in women globally, and drug resistance is among the major obstacles to effective breast cancer treatment. Emerging evidence indicates that photothermal therapy and ferroptosis are both promising therapeutic techniques for the treatment of drug-resistant breast tumors. In this study, we proposed a thermal/ferroptosis/magnetic resonance imaging (MRI) triple functional nanoparticle (I@P-ss-FRT) in which ferritin, an iron storage material with excellent cellular uptake capacity, was attached via disulfide bonds onto polydopamine coated iron oxide nanoparticle (I@P) as photothermal transduction agent and MRI probe. I@P-ss-FRT converted the near-infrared light (NIR) into localized heat which accelerated the release of ferrous ions from ferritin accomplished by glutathione reduction and subsequently induced ferroptosis. The drug-resistant cancer cell lines exhibited a more significant uptake of I@P-ss-FRT and sensitivity to PTT/ferroptosis compared with normal cancer cell lines. In vivo, I@P-ss-FRT plus NIR displayed the best tumor-killing potential with inhibitory rate of 83.46 %, along with a decline in GSH/GPX-4 content and an increase in lipid peroxides generation at tumor sites. Therefore, I@P-ss-FRT can be applied to combat drug-resistant breast cancer.

A photothermal colorimetric dual-signal sensor for Staphylococcus aureus in food based on CuS nanoparticles

Staphylococcus aureus (S. aureus) is a common foodborne pathogenic organism, and rapid detection with high sensitivity and targeted killing are essential for controlling its spread. Therefore, a sandwich structure of magnetic bead-target bacteria-copper sulfide was constructed in this paper. The photothermal conversion function and peroxidase (POD) activity of CuS NPs were utilized to establish a dual sensing platform for temperature and color rendering, that is, after capturing target bacteria, light was converted to heat signal by infrared irradiation. Moreover, the specific detection of S. aureus was realized by detecting the temperature change of the complex and the oxidation of TMB by nano-enzymes of residual CuS in the supernatant to form oxTMB blue product, which formed the change of UV (ultraviolet) − Visible spectroscopy. Based on the high specificity binding and strong signal amplification of the method, the linear range of the photothermal specific probe combined with MBs-S. aureus-CuS was 10–106 CFU/mL, and the detection limit was 1.407 CFU/mL. The linear range of the color specific probe was 10–106 CFU/mL, R2 = 0.9853, and the detection limit was 1.15 CFU/mL. The photothermal efficiency of MBs-S. aureus-CuS system can reach 62.84 %, which has excellent photothermal conversion effect, and the temperature rises to about 70 °C within 7 min, which can directly kill bacteria in the detection. In addition, the portable infrared thermal imager is applied to realize the real-time field detection of S. aureus. The study was significant, because exploratory experiments were conducted to conceive a proof-of-concept based on multiple bacterial sensors that could easily be adapted to a variety of fields where bacteria pose a threat.

Colorimetric and photothermal double-model immunochromatographic assay based on MoS2@Au nanocomposite for high sensitive detection of imidacloprid in food

In this work, a colorimetric and photothermal double-model immunochromatographic assay for the detection of imidacloprid (IMI) was developed using gold nanoparticles (AuNPs) deposited on two-dimensional layered molybdenum disulphide nanosheets (MoS2 NSs). Here, as a signal amplification carrier, the AuNPs on the surface of MoS2 NSs can be well connected with antibody to prepare the photothermal signal probe, this probe has good biocompatibility and high heat conversion efficiency. It is worthing mentioning that the assay realizes the double-mode signal output of semi-quantitative visual detection and quantitative photothermal detection under 808 nm excitation. Under optimal conditions, the limit of detection (LOD) of assay based on photothermal model for IMI was 0.18 μg L-1 and the visual limit of detection (vLOD) of assay based on colorimetric model was 12 μg L-1. The proposed assay has good specificity and other neonicotinoid pesticide analogues have no effect on assay performance. The detection results of this assay were consistent with that of HPLC, indicating the good accuracy of this proposed quantitative detection method. This double-model assay can be used as a promising candidate for sensitive and rapid detection of IMI, which provides a new strategy for real-time monitoring of pesticide residues in food safety test.

Precisely Self-Cooperative Nanoassembly Enables Photothermal/Ferroptosis Synergistic Tumor Eradication.

Ferroptosis is identified as a potential target for anticancer therapy. However, most conventional ferroptosis inducers not only fail to trigger intracellular lipid peroxidation storm, but are also prone to cause ferroptosis-related toxicity through off-target destruction of intracellular antioxidant defense systems. Therefore, a potent and highly tumor-specific ferroptosis induction modality is desired. Herein, a self-cooperative nanomedicine for imaging-guided photothermal ferrotherapy, which is fabricated based on molecular nanoassembly (NA) of DiR (a photothermal probe) and ferrocene (Fc, a reactant of the Fenton reaction), is elaborately exploited. DiR-elicited hyperthermia induces both photothermal therapy (PTT) and a significant acceleration of the kinetics of the Fc-involved Fenton reaction, collaboratively causing a lipid peroxidation storm in tumor cells. In turn, plenty of lipid peroxides boost PTT through the downregulation of heat shock protein 90. As expected, such a self-cooperative NA demonstrates synergetic tumor eradication in the 4T1 breast tumor-bearing mice xenograft model. This study offers a novel nanotherapeutic paradigm for precise multimodal cancer therapy.

Mn-modified porphyrin metal–organic framework mediated colorimetric and photothermal dual-channel probe for sensitive detection of organophosphorus pesticides

Herein, a novel dual-mode probe for organophosphorus pesticides (OPs) colorimetric and photothermal detection was developed based on manganese modified porphyrin metal–organic framework (PCN-224-Mn). PCN-224-Mn had excellent oxidase-like activity and oxidized colorless 3,3,5,5-tetramethylbenzidine (TMB) to blue–green oxidation state TMB (oxTMB), which exhibited high temperature under near-infrared irradiation. l-ascorbate-2-phosphate was hydrolyzed by acid phosphatase to produce ascorbic acid, which weakened colorimetric and photothermal signals by impacting oxTMB generation. The presence of OPs blocked the production of ascorbic acid by irreversibly inhibiting the activity of acid phosphatase, causing the restoration of chromogenic reaction and the increase of temperature. Under the optimal conditions, the probe showed a good linear response to OPs in the concentration range of 5 ∼ 10000 ng/mL, using glyphosate as the analog. The detection limits of glyphosate in colorimetric mode and photothermal mode were 1.47 ng/mL and 2.00 ng/mL, respectively. The probe was successfully used for sensitive identification of OPs residues in tea, brown rice, and wheat flour. This work proposes a simple and reliable colorimetric/photothermal platform for OPs identification, which overcomes the problem that single-mode detection probes are susceptible to external factors, and has broad application potential in the field of food safety.

A novel photothermal sensing probe based on violet phosphorus for sensitive immunochromatographic sensing detection

Photothermal immunochromatographic sensor is an emerging detection technology, and it is important to develop new sensing probes with excellent photothermal performance to improve its detection performance. In the present study, a novel photothermal sensing probe based on violet phosphorus nanosheets with satisfactory photothermal conversion efficiency (31.1 %) was reported for the first time. A photothermal immunochromatographic sensor using the above probe was applied for visual and photothermal detection of diethylstilbestrol. The diethylstilbestrol concentration was inversely proportional to photothermal sensing signal and showed a good linear correlation in the range of 0.75 ∼ 50 μg·L−1. After optimizing, the visual and photothermal detection limits were 6 μg·L−1 and 0.56 μg·L−1, respectively. The recovery rates in tap water, milk and pork samples ranged from 82.2 % to 115.2 %, with a coefficient of variation (CV) ranging from 2.0 % to 10.8 %. This work not only structured a new type of photothermal probe, but also expanded the application range of violet phosphorus.

A pressure-colorimetric multimode system with photothermal activated multiple rolling signal amplification for ovarian cancer biomarker detection

Utilizing the photothermal effect to activate enzyme activity, realize signal conversion and amplification show promising prospects in biosensing. Herein, a pressure-colorimetric multi-mode bio-sensor was proposed through the multiple rolling signal amplification strategy of photothermal control. Under NIR light radiation, the Nb2C MXene labeled photothermal probe caused notable temperature elevation on a multi-functional signal conversion paper (MSCP), leading to decomposition of thermal responsive element and in-situ formation of Nb2C MXene/Ag-Sx hybrid. The generation of Nb2C MXene/Ag-Sx hybrid accompanied with valid color change from pale yellow to dark brown on MSCP. Moreover, the Ag-Sx as a signal amplification element enhanced the NIR light absorption to further improve the photothermal effect of Nb2C MXene/Ag-Sx thereby induce cyclic in situ production of Nb2C MXene/Ag-Sx hybrid with rolling enhanced photothermal effect. Subsequently, the continuously enhanced photothermal effect rolling activated catalase-like activity of Nb2C MXene/Ag-Sx, which accelerated the decomposition of H2O2 and promoted the pressure elevation. Therefore, the rolling-enhanced photothermal effect and rolling activated catalase-like activity of Nb2C MXene/Ag-Sx considerately amplified the pressure and color change. Making full use of multi-signal readout conversion and rolling signal amplification, accurate results can be obtained in a short time, whether in the laboratory or in the patient's homes.

A smartphone-assisted colorimetric and photothermal probe for glutathione detection based on enhanced oxidase-mimic CoFeCe three-atom nanozyme in food

The rational fabrication of point-of-care testing (POCT) featuring simplicity, rapidity, low cost, portability, high sensitivity and accuracy is crucial for maintaining food safety in resource-limited locations and home healthcare but remains challenging. Herein, we report a universal colorimetric-photothermal-smartphone triple-mode sensing platform for POC food-grade glutathione (GSH) detection. This simple sensing platform for GSH detection takes merits of three techniques: commercially available filter paper, thermometer and smartphone via an excellent CoFeCe-mediated oxidase-like activity. This strategy allows CoFeCe three-atom hydroxide to efficiently convert dissolved oxygen into O2·− and catalyzes 3, 3′, 5, 5′-tertamethylbenzidine (TMB) to generate an oxidized TMB with remarkable color changes and photothermal effect, resulting in a colorimetric-temperature-color triple-mode signal output. The constructed sensor exhibits high sensitivity with a limit of detection of 0.092 μM for GSH detection. We expect this sensing platform can be easily modified for the determination of GSH in commercial samples with the simple testing strips.

A photothermal lateral flow immunoassay for zearalenone with high sensitivity and wide detection range

Mycotoxin zearalenone can induce reproductive toxicity and oxidative toxicity, so its on-site monitoring in foods is of great significance in food control. Herein, we develop a novel photothermal lateral flow immunoassay (LFIA) for ZEN based on gold nanoparticle loaded black phosphorus (BP-Au) nanocomposite. The self-assembled BP-Au nanocomposite showed a dark purple color and an excellent photothermal conversion efficiency of 69.62%, better than either BP or Au. Therefore, it was developed into not only a colorimetric probe for qualification but also a sensitive photothermal probe for quantification. Our competitive LFIA showed a detection limit down to 17.2 ng/kg and an ultrawide linear range of 10 pg/mL-106 pg/mL in its photothermal mode. The recoveries of ZEN in cereals were between 91.8% and 120.2%. The wide detection range of our method allows monitoring the variation of trace ZEN content to evaluate food storage and transportation conditions, but also gives regulators a fast and accurate picture of the level of ZEN exceeding limits without relying on laboratory chromatography.

Two birds with one stone: An enzyme-regulated ratiometric fluorescent and photothermal dual-mode probe for organophosphorus pesticide detection

In this study, based on the oxidase activity and photothermal effect of manganese dioxide nanosheets (MnO2 NSs), with thiamine (TH) as the fluorescence response signal and tris (2,2'-bipyridyl) ruthenium (II) hexahydrate as the reference signal, an enzyme-regulated ratiometric fluorescence and photothermal dual-mode probe was constructed for the quantitative detection of organophosphorus pesticide (OPs) residues. OPs reduced the production of the reductive product thiocholine by inhibiting the activity of acetylcholinesterase, thereby regulating the residual amount of MnO2 NSs. With the increase of OPs concentration, the color of the probe solution gradually transitioned from red to blue, and the temperature gradually increased. Using dichlorvos and chlorpyrifos as pesticide models, the developed probes exhibited sensitive responses to OPs in a wide linear range of 0.1–8000 ng/mL. The detection limits of dichlorvos and chlorpyrifos in fluorescence mode were 1.13 × 10−3 ng/mL and 0.86 ng/mL, respectively. The corresponding detection limits in photothermal mode were 1.01 ng/mL and 1.02 ng/mL, respectively. The proposed probe displayed excellent anti-interference and reliability in the analysis of OPs residues in real samples. The dual-mode probe with self-verification function is expected to provide more accurate and robust detection results than the single-mode probe, and has a wider application prospect.

An ultra-sensitive photothermal lateral flow immunoassay for 17β-estradiol in food samples

Hormone residues in food and drinking water endanger human health, therefore, on-site analysis techniques of superior performance are important for monitoring this risk. In this study, an ultra-sensitive photothermal lateral flow immunoassay (LFIA) for quantification of 17β-estradiol (E2) has been developed. Anti-E2 antibody modified black phosphorus-Au (BP-Au) nanocomposite was developed as a photothermal contrast signal probe and the temperature at test-zone was recorded with an infrared camera. Under the irradiation of 808 nm laser at test-zone, it gave temperatures negatively related to the concentrations of E2 in samples. Under optimal detecting conditions, the developed photothermal LFIA exhibited a limit of detection of 50 pg mL−1, over 100-fold more sensitive than visual LFIA, and a linear range of 3 orders of magnitude. This method has been successfully applied to water, milk, and milk powder samples.

A highly sensitive photothermal immunochromatographic sensor for detection of aflatoxin B1 based on Cu2-xSe-Au nanoparticles

In the study, Cu2-xSe-Au nanoparticles (CSA) with a photothermal conversion efficiency of 60.78 % at 808 nm were applied to the construction of thermal analysis immunochromatographic test strips for the highly sensitive quantitative detection of aflatoxin B1 (AFB1) in grain. The CSA was coupled with the AFB1 antibody to form a photothermal sensor probe by physical adsorption. The constructed immunosensor exhibited high sensitivity and a wide linear range from 0.01 to 10 μg/L in PBS. The detection limits of 0.00842 μg/L based on the thermal analysis was significantly improved by 11.88-fold compared with colorimetric results. No cross-reaction with the other mycotoxins was found except for aflatoxin B2, aflatoxin M1, aflatoxin G1 and aflatoxin G2. Applied to analysize grain sample, the method achieved the detection of AFB1 ranging from 0.16 to 160 μg/kg.

Plasmonic Gold Nanostar Mediated Self-Photothermal Modulation of Microfiber Bragg Grating

Photothermal actuation that leverages optical fiber and plasmonic materials would not only add a practical function but also spur many important applications for the fiber-optic sensors, for example, the self-temperature governing and fiber-optic photothermal medicine probe. In this paper, we propose and demonstrate a microfiber Bragg grating device that integrates the functionality of self photothermal modulation mediated by the plasmonic gold nanostar (AuNSt). As an excellent plasmnoic nanomaterial, AuNSt stands out due to its tailorable surface plasmon resonance(SPR) spectrum and pronouced “lightning rod” effect. After exploring the optimized AuNSt colodial solution for immobilization on the fiber surface, the AuNSt-functionalized microfiber Bragg grating presented a high pump-heat slope <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\sim }$</tex-math></inline-formula> 0.06 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C/mw and the maximum temperature elevation of 18.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C in the liquid environment. Furthermore, the enhanced electromagnetic field of AuNSt effectively improves the sensitivity of the microfiber Bragg grating. The functional grating probe also performs good stability and fast on-off switch of the photoheating. The demonstration heralds the potential of the plasmonic microfiber grating for steering the interfacial temperature through the photothermal effect, which will be beneficial for the bio-chemical sensing and medical therapeutics.

Photothermal sensor based on water-soluble CsPbBr3@sulfobutylether-β-cyclodextrins nanocomposite using a thermometer as readout

All-inorganic perovskite quantum dots (CsPbX3 QDs) with bright photoluminescence are suitable for application in optoelectronic field, but their extreme instability and insolubility in aqueous solution limit their development in other fields. Herein, for the first time, we encapsulated CsPbBr3 QDs using sulfobutylether-β-cyclodextrins to form nanocomposite (CsPbBr3@SBE-β-CD nanocomposite) with high water solubility and stability via a host-guest interaction strategy, in which the PL intensity remained above 100% of the initial value after 3 h storage in water. Hydrogen sulfide (H2S) is known to be an important mediator of diverse cellular functions in health and in disease, which is important to develop a selective and portable detection method for H2S. The obtained CsPbBr3@SBE-β-CD nanocomposite was employed to develop a photothermal sensor for quantitative detection of H2S using a thermometer as signal readout. Specifically, the obtained CsPbBr3@SBE-β-CD nanocomposite was used as the photothermal probe while H2S acted as a switch of the photothermal probe, and the photothermal sensor was triggered by the reaction between H2S and CsPbBr3@SBE-β-CD nanocomposite. Notably, the naked eye and fluorescence spectrophotometer could also be the signal readout for this strategy, and their detection range and limit of detection were not better than those of the proposed photothermal sensor. On the basis of this H2S-triggered photothermal sensor, H2S was successfully detected at a concentration as low as 5.0 µM in organs of adult zebrafish at room temperature for 10 min. Such innovative strategy enables new opportunity for the development of affordable assays, especially as point-of-care testing in low-resource settings.

Elaborately Engineering a Self-Indicating Dual-Drug Nanoassembly for Site-Specific Photothermal-Potentiated Thrombus Penetration and Thrombolysis.

Thrombotic cardio‐cerebrovascular diseases seriously threaten human health. Currently, conventional thrombolytic treatments are challenged by the low utilization, inferior thrombus penetration, and high off‐target bleeding risks of most thrombolytic drugs, resulting in unsatisfactory treatment outcomes. Herein, it is proposed that these challenges can be overcome by precisely integrating the conventional thrombolytic strategy with photothermal therapy. After co‐assembly engineering optimization, a fibrin‐targeting peptide‐decorated nanoassembly of DiR (a photothermal probe) and ticagrelor (TGL, an antiplatelet drug) is prepared for thrombus‐homing delivery, abbreviated as FT‐DT NPs. The elaborately engineered nanoassembly shows multiple advantages, including simple preparation with high drug co‐loading capacity, synchronous delivery of two drugs with long systemic circulation, thrombus‐targeted accumulation with self‐indicating function, as well as photothermal‐potentiated thrombus penetration and thrombolysis with high therapeutic efficacy. As expected, FT‐DT NPs not only show bright fluorescence signals in the embolized vessels, but also perform photothermal/antiplatelet synergistic thrombolysis in vivo. This study offers a simple and versatile co‐delivery nanoplatform for imaging‐guided photothermal/antiplatelet dual‐modality thrombolysis.

Integration and Quantitative Visualization of 3,3',5,5'-Tetramethylbenzidine-Probed Enzyme-Linked Immunosorbent Assay-like Signals in a Photothermal Bar-Chart Microfluidic Chip for Multiplexed Immunosensing.

The photothermal effect shows significant promise for various biomedical applications but is rarely exploited for microfluidic lab-on-a-chip bioassays. Herein, a photothermal bar-chart microfluidic immunosensing chip, with the integration of the conventional 3,3',5,5'-tetramethylbenzidine (TMB)-probed enzyme-linked immunosorbent assay (ELISA)-like system, was developed based on exploiting the photothermal pumping technique for visual bar-chart microfluidic immunosensing. Both the sandwich ELISA-like system and the photothermal pumping protocol were integrated into a single photothermal bar-chart chip. On-chip immunocaptured iron oxide nanoparticles catalyzed the oxidation of the chromogenic substrate, TMB, to produce a sensitive photothermal and chromogenic dual-functional probe, oxidized TMB. As the result of heat generation and the subsequent production of elevating vapor pressure in the sealed microfluidic environment, the on-chip near-infrared laser-driven photothermal effect of the probe served as a dose-dependent pumping force to drive the multiplexed quantitative display of the immunosensing signals as visual dye bar charts. Prostate-specific antigen as a model analyte was tested at a limit of detection of 1.9 ng·mL-1, lower than the clinical diagnostic threshold of prostate cancer. This work presents a new perspective for microfluidic integration and multiplexed quantitative bar-chart visualization of the conventional TMB-probed ELISA signals possibly by means of an affordable handheld laser pointer in a lab-on-a-chip format.

Fiber optic probe with functional polymer composites for hyperthermia.

We demonstrate a fiber optic probe incorporating functional polymer composites for controlled generation of photothermal effects. The probe combines carbon-based and rare-earth composites on the tip of standard multimode fibers, thus yielding a compact fiber optic photothermal probe (FOPP) whose temperature can be measured simultaneously through fluorescent thermometry. We evaluate the thermal features of the probe through experiments and numerical calculations showing that large thermal gradients are obtained within the vicinity of the heating zone. The temperatures achieved with the FOPP are within the ranges of interest for hyperthermia and can be attained using low optical powers (< 280 mW).

Application of Molecular Probes in Tumor Treatment

Photothermal therapy refers to the addition of targeted drugs with photothermal effects into the patient's body. Through targeting, the drug specifically recognizes tumor cells and accumulates around tumor cells. Afterwards, it is irradiated with a laser of a specific wavelength to achieve a local temperature increase, thereby achieving the effect of killing or locating tumor cells. Therefore, the most important part of this treatment method is the photothermal probe with a targeting effect and good photothermal effect. The existing photothermal probes are mainly composed of inorganic substances, organic small molecules and organic biomolecules. This paper will mainly introduce the development status and prospects of performance of these three types of photothermal probes to introduce photothermal agent development.