Nafion assisted preparation of prussian blue nanoparticles and its application in electrochemical analysis of l-ascorbic acid

A signal "switch-on" photoelectrochemical sensor based on a 3D-FM/BiOI heterostructure for the sensitive detection of l-ascorbic acid

A highly efficient 3D flower MoS2 (3D-FM)-based heterostructure photocatalyst (3D-FM/BiOI) was successfully obtained via a simple hydrothermal synthesis strategy. 3D-FM/BiOI showed prominent photoelectrochemical performance, distinguished stability and good selectivity. The introduction of 3D-FM, by promoting the photoelectric property attributed to it, facilitated the separation of photogenerated electron-hole pairs. Since the redox process of l-ascorbic acid (l-AA) resulted in an increasing photocurrent of 3D-FM/BiOI, a signal "switch-on" photoelectrochemical sensor (PECS) was designed to sensitively determine l-AA for the first time. Under optimized conditions, the 3D-FM/BiOI PECS worked over a wide range from 1 μM to 0.8 mM with a low detection limit of 0.05 μM (S/N = 3). The PECS was successfully exploited for l-AA sensing in human urine with excellent accuracy and applicability, demonstrating its practical precision and superb serviceability. Furthermore, the 3D-FM/BiOI PECS exhibited satisfactory selectivity and stability, providing a great potential platform for the construction of an l-AA sensor in various practical samples and complicated environments.

A novel electrochemical aptasensor based on polyaniline and gold nanoparticles for ultrasensitive and selective detection of ascorbic acid

Ascorbic acid (AA) is involved in many physiological activities of the body and plays an important role in maintaining and promoting human health. It is also present in many natural and artificial foods. Therefore, the development of highly sensitive and accurate AA sensors is highly desirable for human health monitoring, as well as other commercial application fields. Herein, an ultrasensitive and selective electrochemical sensor based on an aptamer was developed for the determination of AA for the first time. The aptasensor was fabricated by modifying a composite made of polyaniline (PANI) and gold nanoparticles (AuNPs) on a glassy carbon electrode. The morphologies and electrochemical properties of the resulting electrodes were characterized by various analytical methods. The results indicated relatively good electrical conduction properties of PANI for accelerated electron transfer. The modification with AuNPs provided signal amplification, suitable for applications as novel platforms for the sensitive sensing of AA. Under optimized conditions, the proposed aptasensor displayed a wide linear response toward the detection of AA from 1.0 to 1.0 × 105 ng L-1 coupled with a low detection limit of 0.10 ng L-1. The sensor also exhibited excellent selectivity and high stability, with at least 2000-fold higher sensitivity than similar previously reported methods. Importantly, the aptasensor exhibited promising properties for the determination of AA in real fruits, vegetables, and infant milk powder, thereby showing potential for food analysis.

Rapid and sensitive determination of ascorbic acid based on label-free silver triangular nanoplates

In this study, a new method for the detection of ascorbic acid (AA) was proposed. It was based on the protective effect of AA on silver triangular nanoplates (Ag TNPs) against Cl- induced etching reactions. Cl- can attack the corners of Ag TNPs and etch them, causing a morphological shift from triangular nanoplates to nanodiscs. As a result, the solution changes color from blue to yellow. However, in the presence of AA, the corners of Ag TNPs can be protected from Cl- etching, and the blue color of the solution remains unchanged. Using this effect, a selective sensor was designed to detect AA in the range of 0-40.00 μM with a detection limit of 2.17 μM. As the concentration of AA varies in this range, color changes from yellow to blue can be easily observed, so the designed sensor can be used for colorimetric detection. This method can be used to analyze fruit juice samples.

A facile and sensitive magnetic relaxation sensing strategy based on the conversion of Fe3+ ions to Prussian blue precipitates for the detection of alkaline phosphatase and ascorbic acid oxidase

Herein, a novel magnetic relaxation sensing strategy based on the change in Fe³⁺ content has been proposed by utilizing the conversion of Fe³⁺ ions to Prussian blue (PB) precipitates. Compared with the common detection approach based on the valence state change of Fe³⁺ ions, our strategy can cause a larger change in the relaxation time of water protons and higher detection sensitivity since PB precipitate can induce a larger change in the Fe³⁺ ion concentration and has a weaker effect on the relaxation process of water protons relative to Fe²⁺ ions. Then, we employ alkaline phosphatase (ALP) as a model target to verify the feasibility and detection performance of the as-proposed strategy. Actually, ascorbic acid (AA) generated from the ALP-catalyzed L-ascorbyl-2-phosphate hydrolysis reaction can reduce potassium ferricyanide into potassium ferrocyanide, and potassium ferrocyanide reacts with Fe³⁺ to form PB precipitates, leading to a higher relaxation time. Under optimum conditions, the method for ALP detection has a wide linear range from 5 to 230 mU/mL, and the detection limit is 0.28 mU/mL, sufficiently demonstrating the feasibility and satisfactory analysis performance of this strategy, which opens up a new path for the construction of magnetic relaxation sensors. Furthermore, this strategy has also been successfully applied to ascorbic acid oxidase detection, suggesting its expansibility in magnetic relaxation detection.