Reusable and self-sterilization mask for real-time personal protection based on sunlight-driven photocatalytic reaction.

Personal protective masks play critical role in preventing the disease epidemic and resisting pathogenic bacterial infestation. However, large quantities of masks were disposed during COVID-19 epidemic, which caused environmental problem and huge economic burden. Herein, we developed reusable masks with inherent antimicrobial and self-cleaning features under solar irradiation. With spun-bonded nonwoven fabrics (SNF) layer as substrate, copper sulfide@polydopamine nanoparticles are deposited on SNF layer (CuS@PDANPs-SNF), which presents excellent photocatalytic activity. Under solar irradiation, CuS@PDANPs produce abundant of singly linear oxygen (1O2), which inactivates pathogenic bacteria with high efficiency over 99%. Interestingly, CuS@PDANPs-SNF cannot cause high temperature to bring any uncomfortable to the person, which is suitable for human to wear in daily life. Such design effectively protect person from the transmission of viral aerosol. Meanwhile, CuS@PDANPs-SNF masks are reusable and still maintain robust bactericidal ability after washing. The sunlight-mediated self-sterilization at low temperature endows CuS@PDANPs-SNF masks as powerful personal protective equipment for daily protection, which also provides an instructive way for reducing the environmental impact.

A cerium-based fluorescent nanosensor for highly specific detection of glutathione over cysteine and homocysteine.

Ever-increasing attention has been focused on constructing a sensing system for specific detection of glutathione (GSH) over cysteine (Cys) and homocysteine (Hcy), which usually interfere with the GSH detection due to their similar structures and the presence of thiol groups in these amino acids. Here, a novel fluorescence-sensing system is developed for highly specific GSH detection over Cys and Hcy. The sensing system is constructed through facilely mixing dipicolinic acid (DPA) and guanosine 5'-monophosphate (GMP) with cerium acetate at ambient conditions, denoted as DPA-Ce-GMP. The resultant DPA-Ce-GMP possesses fluorescence emission with excellent thermal stability and anti-light bleaching, which can be quenched by copper ions (Cu2+). The GSH, and not Cys or Hcy, can trap Cu2+ from DPA-Ce-GMP, resulting in the restoration of the fluorescence of the sensing system. The limit of detection reaches as low as 7.1 nM. The GSH detection in a real sample of human serum was further explored and exhibits satisfactory recovery. The developed sensing system has the advantages of ease-of-preparation, excellent selectivity and stability, demonstrating its potential application in disease diagnosis in the future.

Smartphone-based enzyme-free fluorescence sensing of organophosphate DDVP.

A novel fluorescence strategy based on the outstanding catalytic capability of CuS nanoparticles (CuSNPs) has been developed for highly sensitive and specific determination of o,o-dimethyl-o-2,2-dichlorovinyl phosphate (DDVP) under enzyme-free and hydrogen peroxide (H2O2)-free conditions. In the presence of DDVP, CuSNPs can catalyze non-fluorescence substratum of Amplex red (AR) into resorufin, which exhibits fluorescence emission at 584 nm under excitation at 540 nm. The sensing system exhibits outstanding specificity and only responds to DDVP and no other organophosphorus pesticides (OPs). A wide linear range is obtained from 0.0001 to 0.1 µg/mL, and the limit of detection (LOD) is 0.1 ng/mL. Furthermore, paper-based test strips have been constructed for visual detection of DDVP under ultraviolet light irradiation. By integrating a smartphone installed with Color Picker APP, point-of-care detection with quantitative determination is realized, demonstrating substantial potential applications of the as-developed assay for in situ detection. Graphical abstract.

Dual stimuli-responsive lanthanide-based phosphors for an advanced full-color anti-counterfeiting system.

Dual stimuli-responsive lanthanide (Ln)-based phosphors were prepared for constructing a multi-level full color anti-counterfeiting system. The encrypted information can be visually read out under UV irradiation. Further triggered by water, not only are the fluorescence colors changed, but so are the patterns of the encrypted information. The Ln-based phosphors can be cost-effectively prepared in a simple way, presenting great potential application in constructing an advanced anti-counterfeiting system with a convenient authentication assay.

A smartphone-integrated ratiometric fluorescence sensing platform for visual and quantitative point-of-care testing of tetracycline.

A smartphone-integrated ratiometric fluorescent sensing system (DPA-Ce-GMP-Eu) for visual and point-of-care testing (POCT) of tetracycline with high sensitivity and accuracy was developed. The blue fluorescence of DPA-Ce-GMP was changed into red by doping with Eu3+ duo to the energy transfer from Ce3+ to Eu3+. Upon exposure to tetracycline, coordination between Eu3+ and tetracycline blocks energy transfer from Ce3+ to Eu3+, converting the fluorescent color from red to blue. The tetracycline detection can be realized within a wide concentration range from 0.01 µM to 45 µM. The limit of detection (LOD) reaches as low as 6.6 nM. To realize quantitative point-of-care detection in real samples, a portable device with smartphone as signal reader and analyzer is further designed to integrate with the DPA-Ce-GMP-Eu sensing platform. The Color Picker APP installed in the smartphone can convert the Red, Green and Blue (RGB) channels of the fluorescence images into digital values. With milk as real sample, tetracycline can be on-site detected with LOD of 10.8 nM. This developed platform presents a great promise for POCT in practical application with merits of low cost, easy carry, simple operation, and excellent selectivity and repeatability.

Tumor-Microenvironment-Induced All-in-One Nanoplatform for Multimodal Imaging-Guided Chemical and Photothermal Therapy of Cancer.

Precisely locating tumor site based on tumor-microenvironment-induced (TMI) multimodal imaging is especially interesting for accurate and efficient cancer therapy. In the present investigation, a novel TMI all-in-one nanoplatform, CuSNC@DOX@MnO2-NS, has been successfully fabricated for chemical and photothermal (Chem-PTT) therapy guided by multimodal imaging on tumor site. Here, the CuS nanocages with mesoporous and hollow structure (CuSNC) acting as nanocarriers provide high capacity for loading the anticancer drug, doxorubicin (DOX). The outer layer of the MnO2 nanoshell (MnO2-NS) acts as "gatekeeper" to control the DOX release until the nanoplatform arrives at the tumor site, where abundant glutathione and H+ decompose MnO2-NS into paramagnetic Mn2+. The magnetic resonance imaging and fluorescent imaging were then triggered to locate the tumor, which was further improved by photothermal imaging on account of the intrinsic property of CuSNC. Guided by the multimode imaging, the combination of chemical therapy upon DOX and photothermal therapy upon CuSNC exhibits eminent efficiency on tumor ablation. The nanoplatform exhibits biocompatibility to avoid unwanted harm to normal tissues during trans-shipment in the body. The investigation thus develops a cost-effective TMI nanoplatform with facile preparations and easy integration of Chem-PTT treatment capabilities guided by multimodal imaging for potential application in precise therapy.

Arsenic Species Analysis at Trace Level by High Performance Liquid Chromatography with Inductively Coupled Plasma Mass Spectrometry.

A sensitive and accurate simultaneous continuous analysis for six arsenic species including arsenobetaine (AsB), arsenocholine (AsC), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenite (AsIII), and arsenate (AsV) has been developed by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). An anion-exchange column of Hamilton PRP-X100 (Switzerland) was applied for separation of the six arsenic species with gradient elution of 1.25 mmol/L Na2HPO4 and 11.0 mmol/L KH2PO4 as the mobile phase A and 2.5 mmol/L Na2HPO4 and 22.0 mmol/L KH2PO4 as the mobile phase B. The linearity ranges for AsB, AsC, MMA, DMA, AsIII, and AsV were between 0.5 and 50.0 µg/L, and the detection limits of the six arsenic species were all within 0.01-0.35 ng/L. The relative standard deviations (RSDs) were within 2.26-3.68% and the recovery rates of samples ranged from 95 to 103%. The proposed method was applied for the arsenic speciation analysis of sediment pore-water samples, which were taken from the supernatant after centrifugation and filtration.

A Asp/Ce nanotube-based colorimetric nanosensor for H2O2-free and enzyme-free detection of cysteine.

A novel colorimetric nanosensor has been developed for high sensitive and selective detection of cysteine (Cys) based on the intrinsic oxidase-like activity of cerium nanotube coordinated with aspartic acid (Asp/Ce-NT). Under the function of Asp/Ce-NT, colorimetric reaction of TMB (3,3',5,5'-tetramethylbenzidine) takes place within five minutes without the assistance of additional oxidizing agents (e.g. H2O2). The oxidase-like activity of Asp/Ce-NT can be modulated by adjusting the ratio of Asp to Ce(NO3)3 during preparation process as well as the chirality of Asp (levogyration/L and dextrorotation/D). Compared with D-Asp/Ce-NT, L-Asp/Ce-NT exhibits more excellent activity which can be specifically depressed by Cys. According to the developed strategy, limit of detection for Cys reaches as low as 33.2 nM. The avoiding use of H2O2 would improve the repeatability and reliability. Nice recoveries from 92.5% to 100.8% are found for Cys detection in serum samples. The developed sensing assay is cost-effective and operated in H2O2-free and enzyme-free condition, providing an effective rapid detection way for practical application in disease monitoring and diagnosis.

A MnO2 nanosheet-based ratiometric fluorescent nanosensor with single excitation for rapid and specific detection of ascorbic acid.

Ascorbic acid (AA) detection in biological sample and food sample is critical for human health. Herein, a MnO2 nanosheet (MnO2-NS)-based ratiometric fluorescent nanosensor has been developed for high sensitive and specific detection of AA. The MnO2-NS presents peroxidase-like activity and can oxidize non-fluorescent substrate of o-phenylenediamine (OPDA) into fluorescent substrate, presenting maximum fluorescence at 568 nm (F568). If MnO2-NS is premixed with AA, the MnO2-NS is then decomposed as Mn2+ by AA, decreasing the fluorescent intensity of F568. Meantime, AA is oxidized as dehydroascorbic acid (DHAA), which can react with OPDA to generate fluorescent substrate. A new fluorescence response is found at 425 nm (F425). The dual fluorescent responses can be excited with a universal excitation wavelength, simplifying the detection procedure. With F425/F568 as readout, limit of detection for AA reaches as low as 10.0 nM. Satisfactory recoveries are found for AA detection in serum and diverse beverages. The ratiometric strategy significantly eliminates false-negative and false-positive results, providing a cost-effective, rapid, and reliable way for AA detection in real sample.

A target-induced logically reversible logic gate for intelligent and rapid detection of pathogenic bacterial genes.

For the first time, a target (pathogenic bacterial gene)-induced logically reversible logic gate was constructed as an intelligent biosensor, which has one-to-one mapping functionality and can rapidly distinguish all information of the two targets, the presence of any target and the absence (or presence) of both of the targets, from the unique output signal pattern.

An Ultrasensitive Fluorescence Sensor with Simple Operation for Cu2+ Specific Detection in Drinking Water.

Whether short-term or long-term, overexposure to an abnormal amount of copper ion does significant harm to human health. Considering its nonbiodegradability, it is critical to sensitively detect copper ion. Herein, a novel fluorescent strategy with a "turn-on" signal was developed for highly sensitive and specific detection of copper ion (Cu2+). In the present investigation, we found that Cu2+ exhibits excellent peroxidase-like catalytic activity toward oxidizing the nonfluorescent substrate of Amplex Red into the product of resofurin with outstanding fluorescence emission under the aid of H2O2. Thus, an enzyme-free and label-free sensing system was constructed for copper ion detection with quite simple operation. To ensure the detection sensitivity and reproducibility, the amount of H2O2 and incubation time were optimized. The limit of detection can reach as low as 1.0 nM. In addition, the developed assay demonstrated excellent specificity and could be utilized to detect copper ion in water samples including tap water and bottled purified water without standing recovery.

Nanozyme-based bio-barcode assay for high sensitive and logic-controlled specific detection of multiple DNAs.

Since HCV and HIV share a common transmission path, high sensitive detection of HIV and HCV gene is of significant importance to improve diagnosis accuracy and cure rate at early stage for HIV virus-infected patients. In our investigation, a novel nanozyme-based bio-barcode fluorescence amplified assay is successfully developed for simultaneous detection of HIV and HCV DNAs with excellent sensitivity in an enzyme-free and label-free condition. Here, bimetallic nanoparticles, PtAuNPs, present outstanding peroxidase-like activity and act as barcode to catalyze oxidation of nonfluorescent substrate of amplex red (AR) into fluorescent resorufin generating stable and sensitive "Turn On" fluorescent output signal, which is for the first time to be integrated with bio-barcode strategy for fluorescence detection DNA. Furthermore, the provided strategy presents excellent specificity and can distinguish single-base mismatched mutant from target DNA. What interesting is that cascaded INHIBIT-OR logic gate is integrated with biosensors for the first time to distinguish individual target DNA from each other under logic function control, which presents great application in development of rapid and intelligent detection.