Search

• A sensitive sensor that utilized oriented probe was developed to detect aflatoxin B 1. • The Fe 2 O 3 -antigen probe directionally connected antibodies and improved bioactivity. • The proposed strategy possessed a low detection limit and wide detection range. • Satisfactory analytical results in real foodstuffs showed the sensor's feasibility. One of the major concerns in the application of nanocarriers in biosensing is the impair of the recognition molecules bioactivity loaded on their surfaces due to harsh and laborious cross-linking and random orientation, resulting in unsatisfactory sensitivity. Herein, we proposed a novel immunochromatographic test strip (FNS-ag-DICTS) by taking advantage of the antigen (ag) modified Fe 2 O 3 nanostructures (FNSs) as new signal tags and goat anti-mouse IgG labeling on the detection line instead of ag, which was used for sensitive detection of aflatoxin B 1 (AFB 1). The fabricated FNS-ag can orientate the Fab region of monoclonal antibodies (mAbs), waiving the intrinsic limitations of traditional nanomaterials labeled mAbs. Under optimal conditions, FNS-ag-DICTS possessed excellent specificity and a wide detection range, with a visual limit of detection (vLOD) of 0.0125 ng mL−1. In addition, the biosensor successfully detected AFB 1 in peanut, green bean and corn, with an average recovery rate of 82.8–124.9%. [ABSTRACT FROM AUTHOR]

Herein, a novel bimodal ratiometric probe for sensitive and selective detection of biothiols (including glutathione (GSH), cysteine (Cys) and homocysteine (Hcys)) was constructed, which was based on the redox reaction between manganese dioxide nanoflakes (MnO 2 NFs) and rhodamine (RhB) and biothiols. When MnO 2 NFs was added into RhB solution, RhB was oxidized to a series of derivatives, accompanying with the colorimetric color changing from purple to light pink and fluorescence changing from red to green. In the presence of GSH, Cys or Hcys, they could reduce MnO 2 NFs to Mn2+, thereby preventing the following oxidization of RhB and the corresponding color and fluorescence changes. The absorption intensity ratio and fluorescence intensity ratio showed good linear relationships with the concentrations of biothiols. The colorimetric detection limits for GSH, Cys and Hcys were 0.057 μM, 0.140 μM and 0.087 μM, respectively. And the fluorescence detection limits were 0.177 μM, 0.282 μM and 0.161 μM. More importantly, this probe was successfully applied to monitor the concentration of GSH/Cys/Hcys in human serum samples, with satisfactory recovery. Thus, this MnO 2 NFs-RhB platform can potentially be a candidate for the detection of biothiols. Image 1 • A bimodal ratiometric probe based on RhB and MnO 2 nanoflakes was fabricated. • This probe utilized the redox reactions between MnO 2 nanoflakes and RhB and biothiols. • It had a high sensitivity and a low detection limit. • It was applied in detecting biothiols in serum sample with satisfactory recoveries. • It can be used for detection biothiols with naked eyes under daylight and UV lamp. [ABSTRACT FROM AUTHOR]

Multiple mycotoxins may co-occurred in a single product and cause serious threats to public health. Herein, a multiplex immunochromatographic assay (mICA) was developed based on novel α-Fe 2 O 3 nanocubes (FNCs) as signal tags for the simultaneous detection of deoxynivalenol (DON) and aflatoxins B 1 (AFB 1). The FNCs with eminent water-dispersibility and stability were synthesized by a one-step hydrothermal process, which can rapidly label monoclonal antibodies (mAbs) to form FNCs-mAb probe. Under optimal experimental conditions, the visual limit of detection for DON and AFB 1 were 0.18 ng/mL and 0.01 ng/mL, respectively, which were at least 2-fold improvement compared with the traditional gold nanoparticles based mICA. Furthermore, DON and AFB 1 residual in mung bean, millet and corn were successfully detected by the proposed biosensor, and the average recovery rates were 93.3%–128.3%. Thus, this work indicated that the developed FNCs-mICA provided a sensitive, rapid and reliable on-site simultaneous detection of multiple mycotoxins. • A multiplex biosensor was constructed to sensitive detect deoxynivalenol and aflatoxins B 1. • The α-Fe 2 O 3 nanocubes with eminent water-dispersibility and stability as signal tags. • The sensor can detect deoxynivalenol and aflatoxins B 1 as low as 0.18 ng/mL and 0.01 ng/mL, separately. • The approach exhibited high selectivity and real food sample testing. [ABSTRACT FROM AUTHOR]

• The Sc nanocubes based immunoassay was developed for detection of imidacloprid. • The Sc nanocubes had large surface area, remarkable intensity and biocompatibility. • The sensor had a low limit of detection and specificity for imidacloprid detection. • Satisfactory analytical results in real samples suggested the sensor's applicability. In this work, a highly sensitive immunochromatographic test strip (ITS) based on Scandium-Tetrakis (4-carboxyphenyl) porphyrin (TCPP) metal–organic framework nanocubes (ScTMNs) was developed for ultrasensitive and facile visual determination of imidacloprid (IDP). TCPP as the porphyrin-based planar ligand and Sc3+ as the metal center were applied to form the ScTMNs via coordination chelation. Giving the credit to its excellent optical characteristics, strong affinity with monoclonal antibodies, and favorable biocompatibility, the ScTMNs was selected as a signal tag. Under optimized conditions, the ITS exhibited a great liner relationship in the range of 0.04–3 ng/mL and the detection limit was 0.04 ng/mL for the IDP detection. Additionally, IDP was successfully detected in tomatoes, millet, corn and carrot samples with satisfied recoveries. To the best of our knowledge, this is the first time that ScTMNs have been used in immunochromatography which are expected to have potential applications in detection of other substances. [ABSTRACT FROM AUTHOR]

With the increasingly serious problem of antimicrobial resistance and the lack of clinical response strategies, the development of new antibacterial materials is imminent. Herein, a VIS/NIR co-irradiation photodynamic-photothermal and oxidase-like synergistic antibacterial platform of transition metal sulfide/TiO 2 nanofibers (TMSs/TiO 2 NFs) is proposed to fight bacterial infection. On one hand, three-dimensional (3D) MoS 2 nanoflowers load can quickly capture the photogenerated electrons of two-dimensional (2D) TiO 2 nanofibers, inhibit the recombination of electron-hole pairs and greatly increase the yield of reactive oxygen species (ROS), thereby overcoming the UV sterilization defects of pure TiO 2 , endowing TiO 2 excellent photodynamic antibacterial ability in the long-wavelength region. On other hand, with the combination of MoS 2 and TiO 2 , the photothermal effect of the 3D/2D heterostructure (MoS 2 /TiO 2 NFs) was significantly enhanced and the local temperature rose to above 50 °C in a short time, which was enough to induce the inactivation of bacterial protein, thereby providing an efficient secondary sterilization effect. In addition, MoS 2 /TiO 2 NFs has fascinating oxidase-like activity, which further accelerated the oxidation of physiologically relevant antioxidants in bacteria. In the end, MoS 2 /TiO 2 NFs exerted outstanding antibacterial efficiencies against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) through the synergy of photodynamic-photothermal and oxidase-like performance. Meanwhile, MoS 2 /TiO 2 NFs antibacterial platform effectively accelerated the healing of S. aureus -infected wounds and showed negligible toxicity and hemolysis on normal cells and tissues. Hence, this study contributed an effective alternative strategy for reducing the use of antibiotics, providing new ideas for application of semiconductor nanomaterials in collaborative combination therapy. [Display omitted] • The 3D/2D TMSs/TiO 2 NFs (MoS 2 /TiO 2 NFs) heterojunctions are successfully prepared in situ. • MoS 2 /TiO 2 NFs heterojunctions are demonstrated to increases the yield of ROS. • MoS 2 /TiO 2 NFs show enhanced photodynamic-photothermal and oxidase-like properties. • MoS 2 /TiO 2 NFs process charming sterilization activity. • MoS 2 /TiO 2 NFs antibacterial agent accelerate S. aureus- infected wound healing. [ABSTRACT FROM AUTHOR]

• A prussian blue nanocubes decomposition-assisted competitive sensor was developed. • With the dissolution of the nanocubes, a decreased T -line intensity was obtained. • The proposed sensor was highly sensitive and selective with a low detection limit. • Satisfactory analytical results in real samples suggests the sensor's applicability. A prussian blue nanocubes decomposition-assisted signal amplification strategy for competitive lateral flow immunoassay (PBNCD-SALFIA) was innovatively proposed to analyze aflatoxin B 1 (AFB 1) in foodstuffs. The signal was amplified on account of the PBNCs can degrade and fade under alkaline condition, which could weak the color of the test- and control-lines, thereby improving the sensitivity of the sensor. The strategy was technically-simple, just using NaOH as an amplifier can realize signal amplification in the competition assay. Under optimized conditions, the enhanced strip exhibited excellent specificity and sensitivity in AFB 1 monitoring with a detection limit of 23 pg/mL, which was approximately 4- and 8-folds lower than those of PBNCs-LFIA (90 pg/mL) and conventional gold nanoparticles-LFIA (175 pg/mL), respectively. Taking the advantage of the color-fading, this platform revealing the lowest detectable concentration of 0.184, 0.368 and 0.184 μg/kg for AFB 1 in corn, peanut and pumpkin seed within 58 min, separately, showing reliable results. [ABSTRACT FROM AUTHOR]

• Developed a sensitive photothermal sensor for deoxynivalenol detecting in food. • Au nanoparticle-enhanced MnO 2 nanoflowers were used as photothermal-sensing probes. • Quantitative analysis was carried out by a thermal imager and infrared thermometer. A sensitive photothermal immunochromatographic test strip (PITS) for the detection of deoxynivalenol (DON) was developed using flower-like gold nanoparticle-deposited manganese dioxide nanocarrier (FMD-G NC) labeled antibodies (Abs) as the photothermal-sensing probe. FMD was used as a template to deposit small gold nanoparticles (GNPs) to synthesize FMD-G NC with large specific surface area and significant photothermal conversion property. The FMD-G-Ab probe was competitively captured by DON target and antigen coated on test line (T -line), forming colorimetric signals under naked eyes and photothermal signals under an 808 nm laser. Under optimal conditions, the PITS exhibited sensitive and specific detection of DON from 0.19 ng mL−1 to 12 ng mL−1 with detection limits of 0.013 ng mL−1, which were over 15-fold and 58-fold more sensitive than visual FMD-G-ITS and traditional GNPs-ITS. In addition, the novel FMD-G-PITS possessed a universal applicability, which could be well applied in green bean, corn, and millet. [ABSTRACT FROM AUTHOR]