Current methods for detecting biotoxins are hindered by complex sample preparation and dependence on sophisticated instrumentation. Consequently, there is an urgent need for innovative solutions that facilitate efficient and portable detection capabilities. Herein, a self-powered biosensing platform based on enzyme-based biofuel cells (EBFCs) is reported for the first time for ultrasensitive detection of aflatoxin B1 (AFB1), utilizing gold-embedded hierarchical porous carbon (Au@HPC) and enzymatic signal amplification. Au@HPC was prepared to function as an electrode material of EBFCs for constructing superior EBFCs, representing a novel application of this composite in a self-powered sensing platform. An aptamer-based selective recognition strategy coupled with enzymatic signal amplification was further implemented to monitor the bioelectrocatalytic response toward AFB1. Synergy of enzymatic signal amplification and high-performance carrier material (Au@HPC) amplified electrical signals, markedly improving the sensitivity of the detection platform. As a result, AFB1 could be reliably identified over a wide concentration range of 0.01–104 pg/mL, with a detection limit reaching the femtogram level (1.52 fg/mL, S/N = 3). This study presents a highly accurate, sensitive, and portable detection method suitable for rapid analysis in real food samples.

In the present study, a novel mesoporous silica/nitrogen-doped graphene composite modified electrode (MS/ NGR/GCE) is prepared using an in-situ electrochemical method. The large specific surface area, excellent loading and electron transfer capabilities of the mesoporous silica/nitrogen-doped graphene composite make the modified electrode favored for electrochemical sensing. The sensing properties of different electrodes towards tannins are investigated, and the results show that MS/NGR/GCE exhibits much better sensing performance than individual graphene or mesoporous silica modified electrodes. Under optimal conditions, the linear range of MS/ NGR/GCE for determination of tannins is 0.10-5.0 mu mol/L and 5.0-80 mu mol/L, respectively, with a detection limit of 0.050 mu mol/L (S/N = 3). These results demonstrate that this study has opened up a new pathway for constructing high-performance nanocomposite electrochemical sensors.

A pyrene-phenol-based fluorescent probe PyP which showed typical intramolecular charge transfer (ICT) and monomer-excimer activities was synthesized by using pyrene carboxaldehyde hydrazone and 4-tert-butyl-2,6-diformylphenol as the raw materials. The effects of solvents on PyP were studied, and the results showed that the color of protic polar solvents (Ethanol, N,N-dimethylformamide, methanol and H2O) were successfully identified. Based on the solvent polarity-regulated PyP monomer-excimer switching, the rapid and highly sensitive ratiometric probe, '' Turn-off '' and '' Turn-on '' multimodal probes were established for detection of trace water content in organic solvents (Dimethyl sulfoxide, N,N-dimethylformamide, ethanol and methanol), with detection limits (3 sigma/k) of 0.0021%, 0.046%, 0.062% and 0.024%. The method was successfully used to detect water content in dimethyl sulfoxide, N,N-dimethylformamide, ethanol and methanol commercial organic solvents, with recoveries ranging from 97.2% to 108.0%. The developed method showed good accuracy and stability, and had good application prospect.

Patulin (PAT) in food is a menace to human health. Hence, a sensitive and precise approach to PAT detection is significant. In this research, an innovative electrochemical assay was developed for sensitively determining PAT by assembling aptamers on a carboxylation hierarchically porous carbon (HPC-COOH) modified glassy carbon electrode. Diverse analytical methods were used to describe electrode morphology, structure, chemical composition, and electrochemistry properties. The HPC-COOH, with a large surface area, played a crucial role as a unique substrate to effectively immobilize aptamers and enhance target PATs' recognition and capture ability. Simultaneously, the excellent electrical conductivity of HPC-COOH was significant for the signal amplification of sensors. Under optimized conditions, the aptasensor enabled efficient PAT detection in a broad concentration range (0.5 to 5.0×106ng/L) with a low detection limit (0.25ng/L). The designed aptasensor showed high sensitivity, selectivity, reproducibility, and stability under optimized conditions. The sensors’ feasibility for practical applications was further demonstrated by analyzing apple juice and haw juice samples.

Functionalization of mesoporous silica foam (MSF) is a feasible strategy to enhance the electrocatalytic performance of designed sensors. Herein, an organic ligand, pyrene-1-carboxaldehyde hydrazone (PCH), is used to functionalize MSF and as a modifier for carbon paste electrodes to construct a Cu2+ detection sensor. The experimental results demonstrate that the PCH functionalization can significantly enhance the sensor's sensitivity and selectivity. Under optimized conditions, the linear range of the prepared electrochemical sensor is 0.0050 - 1.0 μM and 1.0 - 10 μM, and the Cu2+ detection limit is 0.0020 μM. The developed sensor is applied to detect Cu2+ content in standard rice control samples, and the obtained results fall well within the range of marked values. Moreover, the recoveries of the standard addition method are 98.4 - 102.6 %, suggesting the developed sensor's good accuracy and practicability.

Functionalization of mesoporous silica foam (MSF) is a feasible strategy to enhance the electrocatalytic performance of designed sensors. Herein, an organic ligand, pyrene-1-carboxaldehyde hydrazone (PCH), is used to functionalize MSF and as a modifier for carbon paste electrodes to construct a Cu2+ detection sensor. The experimental results demonstrate that the PCH functionalization can significantly enhance the sensor's sensitivity and selectivity. Under optimized conditions, the linear range of the prepared electrochemical sensor are 0.0050-1.0 mu M and 1.0-10 mu M, and the Cu2+ detection limit is 0.0020 mu M. The developed sensor is applied to detect Cu2+ content in standard rice control samples, and the obtained results fall well within the range of marked values. Moreover, the recoveries of the standard addition method are 98.4-102.6 %, suggesting the developed sensor's good accuracy and practicability.

Copper (II) (Cu2+) and 3-nitropropionic acid (3-NPA) are harmful substances usually found in foods. Therefore, establishing rapid, sensitive, and accurate detection method for both of these substances is significant research work. A pyrene-based fluorescent sensor (PP) was synthesized to enable highly selective and sensitive simultaneous detection of Cu2+ and 3-NPA in food samples. Initially, PP showed weak fluorescence because of the photo–induced electron transfer process (PET). Upon the presence of Cu2+, the emission of PP at 454nm enhanced owing to the coordination between PP and Cu2+ which hindered the PET. Additionally, under 365nm UV irradiation, the color of the PP solution transitions from orange to bright blue, allowing for naked-eye detection. The sensor PP demonstrated high selectivity and sensitivity toward Cu2+ compared to other competitive metal ions, with the detection limit was 0.036μM, within a linear range of 0–20μM. The binding stoichiometry between PP and Cu2+ is determined to be 2:1 using the Job’s plot method, with a binding constant (Ka) of 7.2 ×103M−1/2. Furthermore, at lower pH (in the range 2.55–5.98), the emission of PP was also enhanced due to the protonation of PP which suppresses the PET process. Given its sensitive and linear response to acidic pH, PP exhibits excellent sensing performance for detecting 3-NPA, with a low detection limit of 0.32μM, surpassing previously reported methods in terms of detection sensitivity.

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.

The ability to monitor changes in metabolites and corresponding gene transcription within living cells is highly desirable. However, most current assays for quantification of metabolites or for gene transcription are destructive, precluding tracking the real-time dynamics of living cells. Here, we used the intracellular elemental sulfur in a Thiophaeococcus mangrovi cell as a proof-of-concept to link the quantity of metabolites and relevant gene transcription in living cells by a nondestructive Raman approach. Raman spectroscopy was utilized to quantify intracellular elemental sulfur noninvasively, and a computational mRR (mRNA and Raman) model was developed to infer the transcription of genes relevant to elemental sulfur. The results showed a significant linear correlation between the exponentially transformed Raman spectral intensity of intracellular elemental sulfur and the mRNA levels of genes encoding sulfur globule proteins in T. mangrovi. The mRR model was verified independently in two genera of Thiocapsa and Thiorhodococcus, and the mRNA levels predicted by mRR showed high consistency with actual gene expression detected by real-time polymerase chain reaction (PCR). This approach could enable noninvasive assessment of the quantity of metabolites and link the pertinent gene expression profiles in living cells, providing useful baseline data to spectroscopically map various omics in real time.

Microporous aluminum-based metal-organic frameworks (CAU-1) are used to develop a simple and sensitive electrochemical sensor for myricetin (MYR) based on a modified carbon paste electrode (CPE) for the first time. The morphologies and electrochemical properties of the as-synthesized CAU-1 are studied utilizing various analytical methods including scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption-desorption, and electrochemical impedance spectroscopy. In terms of electrochemical oxidation of MYR, CAU-1/CPE with its large number of active micropores and rapid electron transfer demonstrates superior performance compared to the bare CPE. Under optimized conditions, the calibration curve for MYR exhibits a linear range of 1.0-10 μg L-1 and 10-1000 μg L-1 with a detection limit of 0.50 μg L-1. The developed CAU-1/CPE exhibits superior analytical characteristics, compared to previously reported electrochemical sensors for MYR detection. Furthermore, CAU-1/CPE is employed to determine MYR in Myrica bark samples, and the results are consistent with those obtained by high-performance liquid chromatography, demonstrating the excellent potential of CAU-1/CPE for the rapid analysis of MYR in complicated real samples.

In this study, a one-step in situ method was developed for the preparation of mesoporous molecularly imprinted sensor for the determination of indole-3-acetic acid. The as-obtained molecularly imprinted films well maintained the mesoporous structure but numerous microporous formed after removal of indole-3-acetic acid. The molecularly imprinted sensors were characterized by various analytical techniques and the data indicated a substantial increase in the electroactive surface area and electrochemical properties of the as-prepared molecularly imprinted sensor thanks to the micro/nanoporous structure. The sensor also showed much better sensitivity and selectivity toward the electrochemical determination of indole-3-acetic acid when compared to both non-imprinted sensor and bare glassy carbon electrode. Under the optimal experimental conditions, the molecularly imprinted sensor displayed a good linear response toward indole-3-acetic acid from 0.080 to 10 mu M with a detection limit of 0.050 mu M (S/N = 3) and a good selectivity toward common interfering substances. Moreover, the as-prepared molecularly imprinted sensor successfully determined indole-3-acetic acid in real samples composed of soybean sprout and mungbean sprout. In sum, the suggested simple strategy looks promising for the construction of high sensitivity and selectivity electrochemical sensors.

3-硝基丙酸是由节菱孢霉菌等真菌产生的一种有毒代谢产物,常见于霉变甘蔗及其制品中,摄入会损害人的中枢神经系统,严重的可致人死亡.因此,建立准确、高效的3-硝基丙酸检测方法对大众身体健康的防护和推进甘蔗产业的健康有序发展具有重要意义.本文综述了国内外最新的甘蔗及其制品中3-硝基丙酸含量的检测方法,分析了各种方法的优缺点,并对其未来的发展方向进行展望,为构筑更为精准、灵敏、高效的3-硝基丙酸的检测方法提供参考.

In this study, we describe a new and straightforward method of electrode modification for introducing intrinsic defects into hierarchically porous carbon (D-HPC), and we use this method to fabricate a robust carbendazim (CBZ) electrochemical sensor. The characterization results of D-HPC demonstrate that this material possesses a hierarchical porous structure (micropores, mesopores, and macropores) with a large specific surface area (1508.9 m(2) g(-1)). The unique structure and excellent electrical conductivity of D-HPC significantly enhance the electrochemical properties of the CBZ sensor. The active sites formed by defect engineering resulted in a high loading of CBZ molecules on the electrode surface, which allows for the sensor to possess excellent sensitivity. Under optimized conditions, the linear range of the sensor for determination of CBZ concentration was 0.010-1.0 mu M, and the detection limit was 0.0061 mu M. Lastly, we demonstrate the practical applicability of the sensor by using it to determine the concentration of CBZ in river water, lettuce, and soil samples.

In this study, a stable and sensitive acetylcholinesterase biosensor was developed for the electrochemical determination of 3-nitropropionic acid (3-NPA). To this end, NaOH etching was used to activate the surface of the glassy carbon electrode, and the morphologies and electrochemistry properties of the resulting electrodes were characterized by various analytical methods. The results indicated dramatic enhancement in the electrochemical properties of electrodes by NaOH etching. As a result, the etched electrodes were applied as novel platforms for the immobilization of acetylcholinesterase. Accordingly, a sensor based on inhibition of 3-NPA toward the activity of acetylcholinesterase was constructed for the electrochemical determination of 3-NPA. Under the optimal conditions, the inhibition rate was found to be proportional to the logarithm of the concentration of 3-NPA from 0.1 to 30 mu g/L, and the limit of detection was recorded as 0.05 mu g/L. In comparison to conventional detection method, the fabricated biosensor also has added advantages in the form of easy and convenient operation, high sensitivity and better linear range.