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The dysregulation of microRNA (miRNA) expression levels is intricately linked to a myriad of human diseases, and the precise and delicate detection thereof holds paramount significance in the realm of clinical diagnosis and therapy. Herein, a near-infrared (NIR) light-mediated homogeneous photoelectrochemical (PEC) biosensor was constructed for miRNA-155 detection based on NaYF4: Yb, Tm@ZnIn2S4 (NYF@ ZIS) coupled with a three-dimensional (3D) walking nanomotor-assisted CRISPR/Cas12a strategy. The upconverted light emitted by the NYF in the visible and UV region upon NIR light excitation could be utilized to excite ZIS to produce a photocurrent response. The presence of target miRNA-155 initiated an amplification reaction within the 3D walking nanomotor, resulting in the production of multiple nucleic acid fragments. These fragments could activate the collateral cleavage capability of CRISPR/Cas12a, leading to the indiscriminate cleavage of single-stranded DNA (ssDNA) on ALP-ssDNA-modified magnetic beads and the subsequent liberation of alkaline phosphatase (ALP). The released ALP facilitated the catalysis of ascorbic acid 2-phosphate to generate ascorbic acid as the electron donor to capture the photogenerated holes on the NYF@ZIS surface, resulting in a positively correlated alteration in the photocurrent response. Under optimal conditions, the NIR light-initiated homogeneous PEC biosensor had the merits of good linear range (0.1 fM to 100 pM), an acceptable limit of detection (65.77 aM) for miRNA-155 detection. Considering the pronounced sensitivity, light stability, and low photodamage, this strategy presents a promising platform for detecting various other miRNA biomarkers in molecular diagnostic practice.
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Técnicas Biossensoriais , Sistemas CRISPR-Cas , Técnicas Eletroquímicas , Raios Infravermelhos , MicroRNAs , Processos Fotoquímicos , MicroRNAs/análise , Humanos , Limite de DetecçãoRESUMO
Photoreversible color switching systems (PCSSs) exhibiting multi-color responses to visible light are favored for sustainable societal development over those relying on ultraviolet light due to safer operation and better penetration depth. Here, a PCSS capable of multi-color switching responsive to visible light based on highly photoreductive rutile-phase Sn-doped TiO2-x nanoparticles is reported. The Sn-doping significantly red-shifts the absorption band of the nanoparticles to the visible region, improving charge separation and transfer efficiencies and introducing Ti3+ species and oxygen vacancies as internal sacrificial electron donors for scavenging photogenerated holes. The resulting Sn-doped TiO2-x nanoparticles feature exceptional photoreduction ability and activity, thereby enabling photoreversible color switching of various redox dyes operational under visible light illumination. Furthermore, multi-color switching can be achieved via the color overlay effect by combining different redox dyes in one system, opening the door to many advanced applications, as demonstrated in their successful uses for developing visible-light-driven rewritable multi-color light-printing systems and visual information displays.
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Sulfides poisoning of metallic Ni is an important issue in catalyst deactivation. SO2, similar to H2S and other sulfides, is an impurity presented in reactants or during the regeneration steps. Herein, spin-polarized density functional theory calculations were used to study the adsorption and decomposition of SO2 on a pristine and metal-doped Ni(111) surface. The adsorption energy, transition state energy, and partial density of state (PDOS) were calculated. On the pristine Ni(111) surface, ten different configurations were considered, and three typical ones were selected for transition state searching. It was found that the reaction barrier of the first S-O bond dissociation was much higher than that of the second one. Doping the top layer with a second metal could strongly change the adsorption and decomposition behavior. Doping with 3/9ML Co slightly increases the adsorption energy of SO2 for most configurations and decreases the reaction barriers of the SO2-tht-2 decomposition, while the others decrease the adsorption ability and increase the barriers. The order of adsorption energy for the most stable configurations is Co > Ni > Cu > Rh > Pd. The order of the first S-O bond dissociation reaction barriers is Pd > Rh > Cu = Ni > Co, and the order of the second bond dissociation barrier is Rh > Pd > Cu > Ni > Co.
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The development of self-powered flexible multicolor electrochromic (EC) systems that could switch different color without an external power supply has remained extremely challenging. Here, a new trilayer film structure for achieving self-powered flexible multicolor EC displays based on self-charging/discharging mechanism is proposed, which is simply assembled by sandwiching an ionic gel film between 2 cathodic nickel hexacyanoferrate (NiHCF) and Prussian blue (PB) nanoparticle films on indium tin oxide substrates. The display exhibits independent self-powered color switching of NiHCF and PB films with fast responsive time and high reversibility by selectively connecting the Al wire as anodes with the 2 EC films. Multicolor switching is thus achieved through a color overlay effect by superimposing the 2 EC films, including green, blue, yellow, and colorless. The bleaching/coloration process of the displays is driven by the discharging/self-charging mechanism for NiHCF and PB films, respectively, ensuring the self-powered color switching of the displays reversibly without an external power supply. It is further demonstrated that patterns can be easily created in the self-powered EC displays by the spray-coating method, allowing multicolor changing to convey specific information. Moreover, a self-powered ionic writing board is demonstrated based on the self-powered EC displays that can be repeatedly written freehand without the need of an external power source. We believe that the design concept may provide new insights into the development of self-powered flexible multicolor EC displays with self-recovered energy for widespread applications.
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Herein, a novel near-infrared (NIR) light-driven photoelectrochemical (PEC) biosensor based on NaYF4:Yb3+, Er3+@Bi2MoO6@Bi (NYF@BMO@Bi) nanocomposites was elaborately developed to achieve highly sensitive detection of microRNA-155 (miRNA-155). To realize signal enhancement, the coupled plasmonic bismuth (Bi) nanoparticles were constructed as an energy relay to facilitate the transfer of energy from NaYF4:Yb3+, Er3+ to Bi2MoO6, ultimately enabling the efficient separation of electron-hole pairs of Bi2MoO6 under the irradiation of a 980 nm laser. For constructing biosensing system, the initial signal was firstly amplified after the addition of alkaline phosphatase (ALP) in conjunction with the biofunctionalized NYF@BMO@Bi nanocomposites, which could catalyze the conversion of ascorbic acid 2-phosphate into ascorbic acid, and then consumed the photoacoustic holes created on the surface of Bi2MoO6 for the enlarging photocurrent production. Upon addition of target miRNA-155, the cascade signal amplification process was triggered while the ALP-modified DNA sequence was replaced and then followed by the initiation of a simulated biocatalytic precipitation reaction to attenuate the photocurrent response. On account of the NIR-light-driven and cascade amplifications strategy, the as-constructed biosensor was successfully utilized for the accurate determination of miRNA-155 ranging from 1 fM to 0.1 µM with a detection limit of 0.32 fM. We believed that the proposed nanocomposites-based NIR-triggered PEC biosensor could provide a promising platform for effective monitoring other tumor biomarkers in clinical diagnostics.
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Técnicas Biossensoriais , MicroRNAs , Nanocompostos , Técnicas Eletroquímicas , Raios Infravermelhos , Limite de DetecçãoRESUMO
The harsh operating conditions and time-consuming fabrication process of the photoelectrode modification process have limited the potential applications of photoelectrochemical (PEC) sensors. To overcome these drawbacks, this study introduced a unique split-type PEC biosensor for microRNA-21 (miRNA-21) detection. Specifically, a Ti3C2/MgIn2S4 heterojunction was adopted as the photosensitive material, and a target-controlled glucose release system, comprising a multifunctional porphyrin-based metal-organic framework (PCN-224), was used for signal amplification. The Ti3C2/MgIn2S4 heterojunction effectively separated the photogenerated electrons and holes, and improved the photoelectric conversion efficiency, offering a strong initial photocurrent signal during PEC biosensing. Meanwhile, the porous PCN-224 acted as a nimble nanocontainer that encapsulated glucose using a capture probe (CP). In the presence of miRNA-21, the CP formed a CP-miRNA-21 complex and then detached from PCN-224, controllably releasing the trapped glucose. The oxidization of glucose by glucose oxidase resulted in hydrogen peroxide generation, which acted as a scavenger for the holes generated on the surface of Ti3C2/MgIn2S4, and significantly enhanced the photocurrent response under visible light irradiation. Finally, the sensor exhibited good performance for miRNA-21 detection with a low detection limit (0.17 fM) and wide linearity range (0.5 fM-1.0 nM). Thus, the proposed Ti3C2/MgIn2S4-based split-type PEC sensor is a promising tool for sensitive and accurate detection of miRNA-21 and provides an innovative basis for the preparation of other high-performance sensors.
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Técnicas Biossensoriais , MicroRNAs , Técnicas Biossensoriais/métodos , Preparações de Ação Retardada , Técnicas Eletroquímicas/métodos , Glucose , Limite de Detecção , TitânioRESUMO
Objective: To study structure-specific solubilization effect of Sulfobutyl ether-ß-cyclodextrin (SBE-ß-CD) on Remdesivir (RDV) and to understand the experimental clathration with the aid of quantum mechanics (QM), molecular docking and molecular dynamics (MD) calculations. Methods: The experiment was carried out by phase solubility method at various pH and temperatures, while the concentration of Remdesivir in the solution was determined by HPLC. The complexation mechanism and the pH dependence of drug loading were investigated following a novel procedure combining QM, MD and molecular docking, based on accurate pKa predictions. Results: The phase solubility and solubilization effect of RDV in SBE-ß-CD were explored kinetically and thermodynamically for each assessed condition. An optimal drug / SBE-ß-CD feeding molar ratio was determined stoichiometrically for RDV solubility in pH1.7 solution. The supersaturated solubility was examined over time after pH of the solution was adjusted from 1.7 to 3.5. A possible hypothesis was raised to elucidate the experimentally observed stabilization of supersaturation based on the proposed RDV Cation A /SBE-ß-CD pocket conformations. Conclusion: The computational explorations conformed to the experimentally determined phase solubilization and well elucidated the mechanism of macroscopic clathration between RDV and SBE-ß-CD from the perspective of microscopic molecular calculations.
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Smart color switching materials that can change color with a fast response and a high reversibility have attracted increasing attention in color-on-demand applications. However, most of them can only respond to a single stimulus from their external environment, which dramatically limits their broad applications. To address this problem, we report a new strategy in developing a dual pH-/photo-responsive color switching system by coupling the pH-dependent and redox-driven color switchable neutral red (NR) with photoreductive TiO2-x nanoparticles. The biodegradable TiO2-x nanoparticles/NR/agarose gel film shows a rapid color switching between yellow and red upon stimulation with acidic/basic vapors in more than 20 cycles because of the protonation and deprotonation process of NR. Moreover, the film shows interesting photoreversible color switching properties under both acidic and basic conditions, including a fast response time and a high reversibility. Taking advantage of the excellent dual pH-/photo-responsive color switching properties, we demonstrated the potential applications of the TiO2-x nanoparticles/NR/agarose gel film in dynamic rewritable paper, in which the created patterns by photo-printing produce dynamic color changing upon applying an acidic or a basic vapor. We believe that the result will enable a new path for the development of dual- and even multi-responsive color switching systems, broadening their new applications.
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The achievement of photoreversible color switching systems (PCSS) has offered great opportunities for fundamental studies and practical applications. However, the development of PCSS that possessing highly reversible cyclability and on-demand regulation of recoloration process remains a grand challenge. Herein, we report a hydrazine-mediated self-doping strategy for the synthesis of alkaline Ti3+ self-doped TiO2-x nanoparticles, enabling the TiO2-x nanoparticles/methylene blue based PCSS with long photoreversible cyclability and rapid color switching rate. The Ti3+ species as internal sacrificial electron donors significantly improve the photoreductive activity of TiO2-x nanoparticles, which results in fast decoloration rate and long cycling number of the PCSS. Simultaneously, the alkaline property of TiO2-x nanoparticles enhances the oxidation kinetics of the PCSS to dramatically accelerate the recoloration rate. Moreover, the PCSS can be integrated elaborately with biodegradable agarose to form flexible color switching films, which exhibit long-waited on-demand regulation of recoloration rate in a wide range. By taking advantage of photoreversible color switching and time-resolved color changing process, we demonstrate their potential application in self-erasing rewritable paper and transient optical information encryption. This work represents a new strategy for the future development of PCSS and their advanced applications.
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Photoelectrochemical (PEC) sensors are relatively new sensing platforms with high detection sensitivity and low cost. However, the current PEC biosensors dependent on ultraviolet or visible light as the exciting resource cause injuries to biological samples and systems, which restrains the applications in complicated matrixes. Herein, a near-infrared light (NIR)-initiated PEC biosensor based on NaYF4:Yb,Tm@NaYF4@TiO2@CdS (csUCNRs@TiO2@CdS) was constructed for sensitive detection of acute myocardial infarction (AMI)-related miRNA-133a in an immobilization-free format coupled with a hybridization chain reaction and a redox circle signal amplification strategy. A low-energy 980 nm NIR incident laser was converted to 300-480 nm light to excite the adjacent TiO2@CdS photosensitive shell to generate photocurrent by NaYF4:Yb,Tm@NaYF4 upconversion nanorods. Also, magnetic beads were employed for the homogeneous determination of target miRNA-133a to reduce the recognition steric hindrance and improve the detection sensitivity. The photocurrent response was positively correlated with the level of ascorbic acid as the energy donor to consume photoacoustic holes produced on the surface of csUCNRs@TiO2@CdS, which was generated by alkaline phosphatase catalyzation and regenerated by tris(2-carboxyethyl) phosphine reduction upon the appearance of miRNA-133a. Exerting a NIR-light-driven and immobilization-free strategy, the as-constructed biosensor displayed linearly sensitive and selective determination of miRNA-133a with a detection limit of 36.12 aM. More significantly, the assay method provided a new concept of the PEC sensing strategy driven by NIR light to detect diverse biomarkers with pronounced sensitivity, light stability, and low photodamage.
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Técnicas Biossensoriais , MicroRNAs , Nanotubos , Técnicas Eletroquímicas , Raios Infravermelhos , Limite de DetecçãoRESUMO
A biodegradable amphiphilic liquid polymer was designed to form self-emulsifying nanodroplets in water for delivering poorly soluble drugs. The polymer was composed of multiple short blocks of poly(ethylene glycol) (PEG) and poly(caprolactone) (PCL) connected through acid-labile acetal linkages. With an overall average molecular weight of over 18 kDa, the polymer remained as a viscous liquid under room and physiological temperatures. Dispersing the polymer in an aqueous buffer gave rise to highly stable micelle-like nanodroplets with an average size of approximately 15-20 nm. The nanodroplet dispersions underwent reversible temperature-sensitive aggregation with cloud points ranging from 45 to 50 °C, depending on polymer concentration. Nuclear magnetic resonance (NMR) and dynamic light scattering analyses revealed that while the nanodroplets were stable at pH 7.4 for several days, hydrolysis of the acetal linkages in the polymer backbone was much accelerated under mildly acidic pH 5.0, resulting in the formation of large microdroplets. Nile red (NR), a poorly water-soluble fluorophore, can be solubilized in the nanodroplets, and efficient intracellular delivery of NR was achieved. The hydrophobic indocyanine green (ICG) was also encapsulated in the nanodroplets. Near-infrared (NIR) fluorescence imaging and in vivo biocompatibility of the ICG-loaded nanodroplets were demonstrated in mice. In summary, the self-emulsifying nanodroplets of amphiphilic liquid polymer would be a promising material system for poorly soluble drug delivery and imaging in vivo.
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Materiais Biocompatíveis/química , Verde de Indocianina/química , Nanopartículas/química , Poliésteres/química , Polietilenoglicóis/química , Animais , Materiais Biocompatíveis/síntese química , Linhagem Celular Tumoral , Portadores de Fármacos/química , Sistemas de Liberação de Medicamentos , Teste de Materiais , Camundongos , Estrutura Molecular , Tamanho da Partícula , Poliésteres/síntese química , Polietilenoglicóis/síntese química , SolubilidadeRESUMO
Lightweight, broad-band, and highly efficient microwave-absorbing materials (MAMs) with tunable electromagnetic properties are in high demand. However, the absorption properties are limited by the simple loss mechanism in commonly used absorbing materials. Here, we tested the microwave-absorbing properties of Fe-NiS2/NiS/poly(vinylidene fluoride) (PVDF) in the frequency range of 2-18 GHz. For the 2.5% Fe-NiS2/NiS/PVDF with the filling content of 20 wt %, the maximum reflection loss can reach -61.72 dB at 14.88 GHz, and the bandwidth can reach 3.8 GHz with the reflection loss value below -10 dB. Loss mechanisms of different composites were analyzed on the basis of their magnetic and dielectric properties using both experimental and computational methods. The results indicate that strong microwave absorption property is achieved through a balancing of dielectric loss and magnetic loss. These findings present a new strategy for the future design of MAMs.
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The reversible photocatalytic color switching systems (PCSSs) driven by semiconductor nanoparticles have attracted considerable attention because of their wide applications. However, the developed semiconductor nanoparticles with photoreductive activity are mainly limited to TiO2-based photocatalysts, which greatly hinder their broad applications. Here we report a cocapping ligand-assisted strategy for the development of photoreductive BiOCl ultrathin nanosheets with abundant oxygen vacancies. Both the cocapping ligands and oxygen vacancies in BiOCl ultrathin nanosheets act as sacrificial electron donors to efficiently scavenge the photogenerated holes, endowing the BiOCl ultrathin nanosheets high photoreductive activity and thus enabling the photocatalytic color switching of redox dyes, such as methylene blue (MB) and neutral red. By successfully integrating the BiOCl ultrathin nanosheet/MB/H2O color switching system with poly(vinyl alcohol) hydrogel to fabricate a twistable gel film and simultaneously solving the dye-leaching issue of the gel film in a water environment, we further demonstrate its application in a colorimetric oxygen indicator for food packaging, exhibiting high sensitivity to monitor oxygen leakage by the naked eye. We believe the work opens a new avenue for designing photoreductive semiconductor nanomaterials to enrich the PCSSs and their applications.
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Titania nanocrystals have been investigated for fast color switching through photocatalytic reduction of dyes and hexacyanometalate pigments. Here we reveal that direct binding of sacrificial electron donors (SEDs) to the surface of titania nanocrystals can significantly promote the charge transfer rate by more efficiently scavenging photogenerated holes and releasing more photogenerated electrons for reduction reactions. Using diethylene glycol (DEG) as an example, we show that its binding to the nanoparticle surface, which can be achieved either during or after the nanoparticle formation, greatly enhances the photocatalytic reduction in comparison with the case where free DEG molecules are simply added as external SEDs.
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The dynamic dual-stimuli-responsive surface wrinkles on a bilayer film with high bistability are unattainable and attractive for the applications of smart windows and optical displays. Here, we report a new strategy in developing moisture and temperature dual-responsive surface wrinkles on the polyvinyl alcohol/polydimethylsiloxane (PVA/PDMS) bilayer film by rationally designing the modulus changes of the PVA skin layer upon moisture and temperature. By optimizing the thickness of the PVA layer to 4.5 µm, the as-prepared surface wrinkles show long-awaited properties, such as fast response time, excellent reversibility without degradation of optical contrast, and high light transmittance modulation, which greatly outperforms the reported surface wrinkles. Moreover, the surface wrinkles on the bilayer film remain highly bistable without additional energy consumption for more than five months in ambient room conditions both in the opaque and transparent states. These promising dual-stimuli-responsive surface wrinkles on bilayer films hold great promises for various applications triggered by moisture and temperature, such as smart windows and rewritable optical displays.
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The fast and reversible switching of plasmonic color holds great promise for many applications, while its realization has been mainly limited to solution phases, achieving solid-state plasmonic color-switching has remained a significant challenge owing to the lack of strategies in dynamically controlling the nanoparticle separation and their plasmonic coupling. Herein, we report a novel strategy to fabricate plasmonic color-switchable silver nanoparticle (AgNP) films. Using poly(acrylic acid) (PAA) as the capping ligand and sodium borate as the salt, the borate hydrolyzes rapidly in response to moisture and produces OH- ions, which subsequently deprotonate the PAA on AgNPs, change the surface charge, and enable reversible tuning of the plasmonic coupling among adjacent AgNPs to exhibit plasmonic color-switching. Such plasmonic films can be printed as high-resolution invisible patterns, which can be readily revealed with high contrast by exposure to trace amounts of water vapor.
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Photoreversible color switching that can change colors with fast response and high stability is urgently desired in color-on-demand applications. Yet, developing such materials has long been a significant challenge. In this work, a strategy based on the integration of TiO2 nanoparticle (NP) photocatalytic color switching of redox dyes and poly(vinyl alcohol) gel matrix could produce robust and flexible photochromic gels (FPGs) that exhibit fast light-responsive time and high photoreversible stability. Benefited by the soft network structures and monomeric form of redox dyes in the FPG maintained by poly(vinyl alcohol) and ethylene glycol molecules, as well as enhanced photoreductive activity of TiO2 NPs modified by both surface ligands and oxygen vacancies, the FPG exhibits long photoreversible switching cycles (≥50 times), decoloration in a short period of less than 8 s upon UV illumination, and recoloration in 16 min in ambient air and rapidly in 140 s upon near-infrared light illumination. Consequently, the excellent photoreversible color switching of the FPGs is highly applicable as both self-erasing rewritable media and colorimetric oxygen indicators. We believe that the current systems represent a big step forward toward practical applications, such as time-sensitive information storage, colorimetric oxygen sensor, and potentially many other technologies.
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Dynamic manipulation of optical properties through the reversible assembly of plasmonic nanoparticles offers great opportunities for practical applications in many fields. The previous success, however, has been limited to Au nanoparticles. Reversible assembly and plasmonic tuning of Ag nanoparticles (AgNPs) have remained a significant challenge due to difficulty in finding an appropriate surface agent that can effectively stabilize the particle surface and control their interactions. Here, we overcome the challenge by developing a limited-ligand-protection (LLP) strategy for introducing poly(acrylic acid) with precisely controlled coverage to the AgNP surface to not only sufficiently stabilize the nanoparticles but also enable effective control over the surface charge and particle interaction through pH variation. The as-synthesized AgNPs can be reversibly assembled and disassembled and accordingly display broadly tunable coupling of plasmonic properties. Compared to the Au-based system, the success in the reversible assembly of AgNPs represents a significant step toward practical applications such as colorimetric pressure sensing because they offer many advantages, including broader spectral tuning range, higher color contrast, a one-pot process, and low materials and production cost. This work also highlights LLP as a new avenue for controlling the interparticle forces, their reversible assembly, and dynamic coupling of physical properties.
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In this work, three-dimensional nanoflowers with tunable fluorescent properties constructed with mixed Weakley-type polyoxometalates (POMs, Na9[LnW10O36]·32H2O, Ln = Eu, Tb, abbreviated to LnW10) and tetraethylenepentamine (TEPA) have been successfully prepared through a facile ionic self-assembly (ISA) method. The shape and petal size of the nanoflower as well as its fluorescent behaviors can be tuned through varying the ratio of EuW10/TbW10. The varied-temperature emission behaviors at 80-260 K show that the fluorescent intensity of both Tb3+ and Eu3+ decreased with the increase in temperature, which makes them potential luminescent ratiometric thermometers. Moreover, after being mixed with polydimethylsiloxane (PDMS), the as-formed hybrid films showed stable fluorescence along with good transparency. The robustness of the hybrid films was also demonstrated by corrosion resistance upon treatment with strong acid and alkali and thus can be used as a sensor to detect toluene circularly. Our results provide a new avenue to the facile construction of fluorescent composites and demonstrate that the POM complexes can be further used in supramolecular chemistry and nanomaterials.
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A novel pressure-responsive polymer composite film was developed based on Ag@Au composite nanoplates (NPLs) and polyvinylpyrrolidone (PVP) by using Au nanoparticles as concentration reference. The orientation change of Ag@Au NPLs is impelled by the deformation of polymer matrix under pressure, resulting in its localized surface plasmon resonance (LSPR) intensity change of in-plane dipolar peak. The intensity ratio between plasmon peak of Au nanoparticles and in-plane dipolar peak of Ag@Au NPLs relies on the intensity and duration of pressure. By adjusting the viscosity of the polymer, the orientation change of LSPR may respond to a wide range of stresses. This pressure sensitive film can be utilized to record the magnitude and distribution of pressure between two contacting surfaces via optical information.