A simple photoelectrochemical aptasensor based on MoS2/rGO for aflatoxin B1 detection in grain crops.

Designing a simple and sensitive photoelectrochemical (PEC) sensor is crucial to addressing the limitations of routine analytical methods. The sensitivity of the PEC sensor, however, relies on the photoelectric material used. In this manuscript, composites of MoS2/rGO (MG) with a large area and layered structure are prepared by simple steps. This material exhibits sensitivity to visible light and demonstrates outstanding photoelectric conversion performance. The constructed PEC aptasensor using this material to detect aflatoxin B1 (AFB1) shows significantly higher sensitivity and stability compared to similar sensors. This may be attributed to the presence of surface defects in MoS2, which provide more active sites for photocatalysis. Additionally, graphene oxide (GO) is reduced to rGO by thiourea and forms a heterojunction with MoS2, enhancing charge carrier separation and interfacial electron transfer. Our research has revealed that the photocurrent intensity of the aptamer electrode decreases with an increase in AFB1 concentration, resulting in a "signal-off" PEC aptasensor. The detection limit of this aptasensor is 2.18 pg mL-1, with a linear range of 0.001 to 100 ng mL-1. This result will also provide a reference for the study of other mycotoxins in food.

A Tröger's base-linked aluminium phthalocyanine polymer for discriminative electrochemical sensing of the antibiotic isoniazid.

Isoniazid is a first-line drug used to treat tuberculosis. However, its excessive use can lead to serious adverse effects. Thus, strict monitoring of the isoniazid levels in medications and human systems is required. In this study, a new polymer (AlPc-TB POP) containing a metal phthalocyanine and Tröger's base was synthesized and explored as an electrocatalyst for the oxidation of isoniazid. The results indicated that the polymer is an excellent electron-transfer medium for isoniazid oxidation. The AlPc-TB POP-based sensor quantified isoniazid in the linear range of 0.1-130 µM, with a detection limit of 0.0185 µM. The response of the developed sensor to isoniazid was reproducible and stable. Furthermore, this method can accurately determine isoniazid levels by ignoring the influence of common interfering species in tablets and biological samples. This study contributes to the development of nitrogen-rich porous organic polymers and offers a novel strategy for addressing challenges in disease therapeutic efficacy and public safety monitoring.

Conductive phthalocyanine-based porous organic polymer as sensing platform for rapid determination of vanillin.

Vanillin (Van) is widely utilized in processed foods and medicines for its appealing scent and multiple therapeutic benefits. However, its overconsumption poses a risk to public health, making its quantification essential for ensuring food and medicine safety and quality. This study introduces a stable and conductive phthalocyanine-based porous organic polymer (NiPc-CC POP), synthesized through a straightforward electrophilic substitution of nickel tetra-amine phthalocyanine (NiTAPc) with cyanuric chloride (CC). Appropriate characterization techniques were employed to determine the morphologies and structures of the synthesized materials. Furthermore, the NiPc-CC POP was applied to devise a sensitive Van detection method. Leveraging the high electrocatalytic activity of NiPc-CC POP toward Van oxidation, a linear response of 0.15-32 µmol L-1 was achieved, along with an exceptional detection limit of 0.10 µmol L-1. The sensor demonstrated high selectivity and stability. Samples of human serum and tablets spiked with Van were analyzed, yielding satisfactory recoveries. Consequently, this work contributes to the advancement of sensitive detection platforms for Van at minimal concentrations.

A Sensitive Photoelectrochemical Sensor for Levodopa Detection Using Benzothiadiazole-Based Conjugated Microporous Polymer-Coated Graphene Heterostructures.

Since the 1960s, levodopa (LDA) has been the standard drug for treating of Parkinson's disease. In this study, a novel benzothiadiazole-based conjugated microporous polymer-coated graphene heterostructure (CMP-rGO) was synthesized and used to construct a sensitive photoelectrochemical (PEC) sensor capable of detecting LDA. Under optimal experimental conditions, the intensity of the photocurrent produced by the sensor was linear from 0.005 to 40 µM, and the limit of detection of the sensor was 0.0027 µM. The sensor showed good repeatability, stability, and selectivity for LDA detection. Finally, the constructed sensor was used to detect LDA in levodopa tablets, human serum samples, and urine samples and satisfactory results were obtained. Therefore, the PEC sensor provides a novel platform for the detection of LDA in real samples and broadens the applications of conjugated microporous polymers in PEC sensing.

Photoelectrochemical detection for 3,3',4,4'-tetrachlorobiphenyl in fish based on synergistic effects by Schottky junction and sensitization.

In this study, a novel signal amplification strategy on photoelectrochemical (PEC) aptasensor was designed for high-sensitivity and -selectivity detection of 3,3',4,4'-tetrachlorobiphenyl (PCB77) on the basis of Schottky junction and sensitization. First, the Schottky barrier not only provided an electron-transfer irreversible passage from CuO to Au Nanoparticles (NPs) but also generated excellent local surface plasmon resonance between CuO and Au NPs, thus improving the efficiency of charge separation and light absorption. Second, to further improve the response of the PEC aptasensor under the action of the sensitization, the complementary-DNA-functionalized CdS quantum dots were introduced onto the surface of CuO/Au NPs via hybridization of the target aptamer. The PEC aptasensor exhibited a low detection limit of 17.3 pg L-1, and a wide linear response was shown at a range of 0.2-220 ng L-1 depending on the variation of photocurrent before and after incubation.

Au Quantum Dot/Nickel Tetraminophthalocyanaine-Graphene Oxide-Based Photoelectrochemical Microsensor for Ultrasensitive Epinephrine Detection.

Owing to the importance of epinephrine as a neurotransmitter and hormone, sensitive methods are required for its detection. We have developed a sensitive photoelectrochemical (PEC) microsensor based on gold quantum dots (Au QDs) decorated on a nickel tetraminophthalocyanine-graphene oxide (NiTAPc-Gr) composite. NiTAPc was covalently attached to the surface of graphene oxide to prepare NiTAPc-Gr, which exhibits remarkable stability and PEC performance. In situ growth of Au QDs on the NiTAPc-Gr surface was achieved using chemical reduction at room temperature. The synthesized materials were characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and electrochemical impedance spectroscopy. Au QDs@NiTAPc-Gr provided a much greater photocurrent than NiTAPc-Gr, making it suitable for the ultrasensitive PEC detection of epinephrine. The proposed PEC strategy exhibited a wide linear range of 0.12-243.9 nM with a low detection limit of 17.9 pM (S/N = 3). Additionally, the fabricated PEC sensor showed excellent sensitivity, remarkable stability, and good selectivity. This simple, fast, and low-cost strategy was successfully applied to the analysis of human serum samples, indicating the potential of this method for clinical detection applications.

Novel porous iron phthalocyanine based metal-organic framework electrochemical sensor for sensitive vanillin detection.

Vanillin is widely used as a flavor enhancer and is known to have numerous other interesting properties, including antidepressant, anticancer, anti-inflammatory, and antioxidant effects. However, as excess vanillin consumption can affect liver and kidney function, simple and rapid detection methods for vanillin are required. Herein, a novel electrochemical sensor for the sensitive determination of vanillin was fabricated using an iron phthalocyanine (FePc)-based metal-organic framework (MOF). Scanning electron microscopy and transmission electron microscopy showed that the FePc MOF has a hollow porous structure and a large surface area, which impart this material with high adsorption performance. A glassy carbon electrode modified with the FePc MOF exhibited good electrocatalytic performance for the detection of vanillin. In particular, this vanillin sensor had a wide linear range of 0.22-29.14 µM with a low detection limit of 0.05 µM (S/N = 3). Moreover, the proposed sensor was successfully applied to the determination of vanillin in real samples such as vanillin tablets and human serum.