Activity

In this work, a multicolor visual immunoassay platform was developed. The photoelectric effects of Ag2S NPs@ZnO NTs made the color changes of PANI/PB, which enabled visual inspection of CEA. Under the visible light excitation, Ag2S NPs@ZnO NTs generates electron-holes. Where, photoelectrons will pass electrical circuit to PB and photoinduced holes will oxidize PANI, which making the PANI/PB composite changes from emerald green-blue-purple-black colors. Selleckchem PX-478 When CEA was incubated, the migration rate of photogenerated carriers is slowed down owing to the steric hindrance, resulting in different color changes of PANI/PB. In addition, the average green channel of PANI/PB read by photoshop has a certain correlated linear relationship with the concentration of CEA. Meanwhile, we can observe the color transformation of PANI/PB with our own eyes. By integrating advantages of photoelectrochemistry and colorimetry, the linear range of CEA detection was 0.1-20 ng/mL, and the detection limit was 0.05 ng/mL (S/N = 3). More importantly, this multicolor sensing method is very convenient, simple and low-cost. The photocarriers-modulated colorimetric strategy also provides a novel idea for visual portable platform design in clinical diagnosis. It is still a high challenge to develop a simple, sensitive and portable approach for bioassay in strong scattering medium. Herein, a photoacoustic (PA) device is developed for the detection of alkaline phosphatase (ALP) in serum with silver nanoparticles (AgNPs) as signal probe, without any requirements for expensive equipment, professional operation and pre-processing of real samples. ALP as an important disease marker could catalyze the breakdown of sodium L-ascorbyl-2-phosphate (AAP) into ascorbic acid (AA), thereby reducing Ag+ to AgNPs. AgNPs could generate strong PA signal under the irradiation of modulated 638-nm laser due to their localized plasmon resonance, and detected by the self-made portable PA device. Under the optimized experimental conditions, the present PA device exhibits excellent photostability and reproducibility with the relative standard deviation (RSD) of 2.2% at the concentration of 25 U L-1 ALP. Linear calibration graph is obtained within 5-70 U L-1 for ALP, along with a detection limit of 1.1 U L-1. This portable PA device is applied to detect ALP in serum samples, providing satisfactory spiking recoveries and competitive analytical performances with the current techniques. The PA-based analytical strategy obviously opens up a new avenue to the detection of disease-correlated biomarker in practice. Two novel fluorescent probes were designed to detect the biothiol in foods using the highly efficient Michael addition reaction between maleimide-derived probes and the biothiol. First, maleimide functionalized GQDs (M-GQDs) were synthesized and used for biothiol identification according to the Michael addition principle. The biothiol can be detected in the range of 5 × 10-9 to 4 × 10-7 mol/L and the detection limit was 1.69 × 10-9 mol/L. Then, a fluorescence resonance energy transfer (FRET) system between M-GQDs and tetrakis (4-aminophenyl) porphyrin (TAPP) for biothiol detection was developed. However, the process of FRET was switched off in the presence of biothiols due to the switch of M-GQDs fluorescence emission to the”ON” mode following the Michael addition mechanism. The system could quickly and accurately detect the biothiol with a detection range of 6.7 × 10-10 to 2 × 10-7 mol/L and a detection limit of 2.34 × 10-10 mol/L. Compared to the single detection system, the FRET system had a wider detection range and lower detection limit, and the related biomolecules did not interfere with the quantitative identification of the biothiol. The proposed method was successfully applied for the determination of the biothiol in foods and human blood samples. V.Two new hydroxyl-containing polyimides (PIs) with excellent comprehensive performances were designed and synthesized. After PIs react with fluoride ion (F-), the resulting polyimide-fluoride complexes (PI-1·F and PI-2·F) are exploited as ratiometric and colorimetric sensors for detecting trace water in DMSO/DMF with high sensitivity. Both sensors PI-1·F and PI-2·F exhibit a good naked-eye visual detection as well as an excellent linear relationship between the UV-vis absorbance ratio and the low water content in DMSO/DMF, which constitutes a quantitative method for determining water content in DMSO/DMF. The limits of detection (LOD) of sensor PI-1·F for water in DMSO and DMF are as low as 0.0035% and 0.0031% (v/v), respectively. The sensor PI-2·F shows the higher sensitivity for water detection with extremely low detection limits of 0.00084% and 0.0015% in DMSO and DMF, respectively. Furthermore, PI films have been directly used for the visual sensing of water in acetonitrile, acetone and ethanol, which provides an effective way for fabricating high-performance film-based water sensor devices. In this study, sandwich chemiluminescent immunoassay (CLIA) for the detection of Staphylococcal enterotoxin B (SEB) was developed using nanobody-alkaline phosphatase (Nb-ALP) fusion protein. The SEB-binding nanobodies were obtained from a naïve phage-display library and the Nb-ALP fusion protein was constructed and obtained as a thermally stable and potentially effective substance for detecting antibodies in CLIA. The working range of the sandwich CLIA based on anti-SEB monoclonal antibodies (mAbs) and our fusion protein, Nb37-ALP, was 3.12-50.0 ng mL-1 with SC50 = 8.59 ± 0.37 ng mL-1. The limit of detection was 1.44 ng mL-1 according to the blank value plus 3 standard deviations. In order to understand the interaction of SEB and Nb37 in depth, the 3D structure of the SEB-Nb37 complex was constructed and verified by molecular modeling and the docking method. The results showed that the complementary-determining region 3 (CDR3) of Nb37 embedded itself in the opening generated by the major histocompatibility complex (MHC) and T-cell receptor- (TcR) binding sites of SEB, indicating that Nb37 may affect the recognition of SEB by MHC class Ⅱ molecules and the TcR. The arginine residue (Arg) 101, Arg102 and phenylalanine residue (Phe)103 of CDR3 in Nb37 may have contributed to specific binding to form six salt-bridges between these and SEB. In conclusion, in terms of their specificity and sensitivity, the obtained anti-SEB Nb-ALP appears to have the potential to replace chemically labeled probes for the detection of SEB. V.