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Alkaline phosphatase (ALP) is among the most studied enzymes by far, playing an important role in the metabolism of organisms and the regulation of protein activity. Herein, a label-free composite nanoprobe is constructed by combining inorganic nanomaterials and aggregation-induced emission (AIE) molecule to achieve highly sensitive and selective detection of ALP. Negatively charged 9,10-bis [2-(6-sulfonatopropoxyl) naphthylethenyl] anthracene (BSNVA) molecule is synthesized, which has the AIE performance and can be assembled on the surface of amino–SiO2 nanoparticles through electrostatic interaction for fluorescence enhancement. MnO2 nanosheets are rich in negative charges, enabling them to be wrapped on the surface of the amino–SiO2 nanosphere to shield the positive charge on its surface, making it impossible for BSNVA to accumulate on the surface and then weakening the bio-fluorescence of the system. Furthermore, with catalyzed substrates induced by ALP, generating ascorbic acid and the redox reaction between ascorbic acid and MnO2, the nanoprobe helps in realizing the high-sensitivity detection of ALP with a detection limit of 0.38 mU/mL. The proposed strategy requires no complex cleaning and modification processes and can overcome the quenching effect caused by the aggregation of traditional organic dyes, proving to be a simple, low-cost and "turn-on" fluorescent detection method for ALP. [ABSTRACT FROM AUTHOR]

Highlights: [•] The ionotropic crosslinking interactions result in the coacervation of chitosan. [•] A phosphonate-assisted encapsulation of proteins in chitosan matrix is introduced. [•] The encapsulated proteins retain their bioactivity. [•] The encapsulation method can be used to fabricate various chitosan-based biosensors. [Copyright &y& Elsevier]

A nonenzymatic iron(iii) diethylenetriaminepentaacetic acid (FeIII-DETPA) complex based amperometric sensor for the analytical determination of hydrogen peroxide was developed. By combining the electrostatic interaction between the FeIII-DETPA complex and polyallylamine (PAH) functionalized multiwalled carbon nanotubes (MWCNTs) as well as the ionotropic crosslinking interaction between PAH and ethylenediamine-tetramethylene phosphonic acid (EDTMP), the electroactive FeIII-DETPA complex was successfully incorporated within the MWCNT matrix, and firmly immobilized on the Au substrate electrode. The fabricated electrochemical sensor was characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical methods. The influences of solution pH and ionic strength on the electrochemical sensor were investigated. The prepared electrochemical sensor had a fast response to hydrogen peroxide (＜3 s) and an excellent linear range of concentration from 1.25 × 10−8 to 4.75 × 10−3 M with a detection limit of 6.3 × 10−9 M under the optimum conditions. [ABSTRACT FROM AUTHOR]

The alteration in protein conformation not only affects the performance of its biological functions, but also leads to a variety of protein‐mediated diseases. Developing a sensitive strategy for protein detection and monitoring its conformation changes is of great significance for the diagnosis and treatment of protein conformation diseases. Herein, a plasmon‐enhanced fluorescence (PEF) sensor is developed, based on an aggregation‐induced emission (AIE) molecule to monitor conformational changes in protein, using prion protein as a model. Three anthracene derivatives with AIE characteristics are synthesized and a water‐miscible sulfonate salt of 9,10‐bis(2‐(6‐sulfonaphthalen‐2‐yl)vinyl)anthracene (BSNVA) is selected to construct the PEF–AIE sensor. The sensor is nearly non‐emissive when it is mixed with cellular prion protein while emits fluorescence when mixed with disease‐associated prion protein (PrPSc). The kinetic process of conformational conversion can be monitored through the fluorescence changes of the PEF–AIE sensor. By right of the amplified fluorescence signal, this PEF–AIE sensor can achieve a detection limit 10 pM lower than the traditional AIE probe and exhibit a good performance in human serum sample. Furthermore, molecular docking simulations suggest that BSNVA tends to dock in the β‐sheet structure of PrP by hydrophobic interaction between BSNVA and the exposed hydrophobic residues. 9,10‐bis[2‐(6‐sulfonatopropoxyl)naphthylethenyl]anthracene (BSNVA) molecules with aggregation‐induced emission performance are introduced into a plasmon‐enhanced fluorescence system to build a hybrid sensor, and the fluorescence intensity of BSNVA is enhanced by the core–shell gold nanocube. Based on the specific recognition of proteins by the aptamer and the interaction between the protein and BSNVA, the sensor is applied to turn‐on detection of prion proteins and monitor its conformational transformation. [ABSTRACT FROM AUTHOR]

In this study, three kinds of CDs with blue, yellow and red emissions were prepared and their luminescence mechanisms through theoretical calculations together with experimental data were further investigated in depth. Afterwards, a sensor array was constructed by using three kinds of CD–metal ions for rapid discrimination of different types of sulfur-containing species. [ABSTRACT FROM AUTHOR]