Enzymatic sensing of tyrosine in egg and cheese samples using electrochemical sensor amplified with reduced graphene oxide

Recent advances and challenges in graphene-based electrochemical biosensors for food safety

Ensuring food safety is a critical global concern, particularly in light of recent pandemics and rising contamination risks from pesticides, antibiotics, toxins, and allergens. These contaminants pose significant health hazards, including neurological disorders, endocrine disruption, antibiotic resistance, and carcinogenic effects. Regulatory agencies such as the Food and Agriculture Organization (FAO), the World Health Organization (WHO), and the United States Food and Drug Administration (FDA) have established strict maximum residue limits (MRLs) to mitigate these risks. However, enforcement remains challenging due to limitations in current detection methods. The increasing global population and limited food resources have exacerbated food security challenges, while contaminants can infiltrate food at various stages, including production, processing, and packaging. Despite consumer awareness, significant amounts of food are discarded due to quality concerns. To address these issues, researchers are actively developing low-cost, reliable sensing technologies for real-time food quality assessment and contamination detection. Among these, graphene-based electrochemical biosensors have emerged as a promising solution due to their high sensitivity, selectivity, and cost-effectiveness. This review provides an in-depth analysis of recent advancements in graphene-based electrochemical biosensors, focusing on their role in detecting foodborne hazards and improving food quality monitoring. By integrating selective layers, these sensors enhance detection efficiency and provide an innovative solution for safeguarding public health. The findings underscore the transformative potential of graphene-derived biosensors in food safety diagnostics, paving the way for more reliable and sustainable food monitoring systems.

Rapid determination for tyrosine isomers in food based on N-acetyl-L-cysteine/Upconversion nanomaterials target-induced quench by chiral Electrochemiluminescence sensor

Rapid determination of amino acid isomer is very important for the evaluation of the amino acid nutrition in different foods, so a fast and sensitive electrochemiluminescence (ECL) sensor was innovatively fabricated for the determination of tyrosine isomers in foods based on N-Acetyl-L-cysteine/upconversion nanomaterials possessed a good particular selectivity to L-tyrosine. Under the optimal conditions, for L-tyrosine, the limit of detection (LOD) of the sensor for L-tyrosine was 2.87 × 10-6 M, detection range of 5.5 × 10-5-5.5 × 10-3 M, for D-tyrosine, LOD was 2.56 × 10-5 M, detection range was from 5.5 × 10-4 to 5.5 × 10-3 M. The developed chiral sensor was used to determinate the tyrosine isomers in foods successfully, which provided a convenient method to quickly evaluate the nutritional value of amino acids in food.

A new electroanalytical approach for sunset yellow monitoring in fruit juices based on a modified sensor amplified with nano-catalyst and ionic liquid

The determination of food additives is one of the major points in the food industry that directly is relative to human health. This research work focused on sensing and monitoring sunset yellow as azo additive dyes in fruit juices using an electrochemical sensor amplified with Ni doped Pt decorated carbon nanotubes (NiO/Pt/CNTs) as nano-catalyst and 1-hexyl-3-methylimidazolium chloride ([HMIM][Cl]) as an ionic liquid binder. Carbon paste electrode (CPE) amplified with NiO/Pt/CNTs and [HMIM][Cl] (CPE/([HMIM][Cl])/NiO/Pt/CNTs) improved the sensitivity of sunset yellow sensing in aqueous solution in acidic condition and successfully monitored this azo dye in concentration range 1.0 nM-280 μM with detection limit 0.4 nM. On the other hand, the CPE/([HMIM][Cl])/NiO/Pt/CNTs was used for sensing and analysis of sunset yellow in different fruit juices, and recovery data between 98.65% and 103.66% confirmed the powerful ability of sensor for monitoring of sunset yellow in food samples.

Biosynthesis of Ag-Pt bimetallic nanoparticles using propolis extract: Antibacterial effects and catalytic activity on NaBH4 hydrolysis

The critical environmental issues of antibiotic resistance and renewable energies supply urge researching materials synthesis and catalyst activity on hydrogen production processes. Aiming to analyse the antibacterial effect of platinum-silver (Ag-Pt) nanoparticles (NPs) and the catalyst effect on NaBH₄ hydrolysis that can be used for hydrogen generation technology, in this work, Ag-Pt NPs were prepared using aqueous propolis extract. Various methods were used for the characterization (Uv-vis Spectroscopy, Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM) and X-ray diffraction Spectroscopy (XRD)). The antimicrobial activity of Ag-Pt bimetallic nanoparticles was evaluated in vitro by the microdilution method against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae, Staphylococcus epidermidis, and Serratia marcescens. The results confirmed the antimicrobial activity of bimetallic NPs Ag-Pt concentrations of (25, 50, and 100 μg/ml). A concentration of 100 μg/ml showed low bacterial viability varying between 22.58% and 29.67% for the six tested bacteria. For the catalyst activity on NaBH₄ hydrolysis, the results showed high turnover factor (TOF) and low activation energy of 1208.57 h^-1 and 25.61 kJ/mol, respectively, with high hydrogen yield under low temperature. Synthesized Ag-Pt NPs can have great potential for biological and hydrogen storage applications.

Quantification of Tyrosine in Pharmaceuticals with the New Biosensor Based on Laccase-Modified Polypyrrole Polymeric Thin Film

Stress, a state of body tension, sometimes caused by increased levels of tyrosine (Tyr) in the body, can lead to serious illnesses such as depression, irritability, anxiety, damage to the thyroid gland, and insomnia. The body can be provided with an adequate concentration of tyrosine by taking pharmaceutical products or by dietary intake. Therefore, this study presents the development of a new enzyme sensor for the quantification of Tyr in pharmaceuticals. A screen-printed carbon electrode (SPCE) was modified with the conductive polymer (CP) polypyrrole (PPy) doped with hexacyanoferrate (II) anion (FeCN), the polymer having been selected for its excellent properties, namely, permeability, conductivity, and stability. The enzyme laccase (Lacc) was subsequently immobilized in the polymer matrix and cross-linked with glutaraldehyde, as this enzyme is a thermostable catalyst, greatly improving the performance of the biosensor. The electrochemical method of analysis of the new device, Lacc/PPy/FeCN/SPCE, was cyclic voltammetry (CV), and chronoamperometry (CA) contributed to the study of changes in the biosensor with doped PPy. CV measurements confirmed that the Lacc/PPy/FeCN/SPCE biosensor is a sensitive and efficient platform for Tyr detection. Thus, this enzyme sensor showed a very low limit of detection (LOD) of 2.29 × 10-8 M, a limit of quantification (LOQ) of 7.63 × 10-8 M, and a very high sensitivity compared to both devices reported in the literature and the PPy/FeCN/SPCE sensor. Quantitative determination in pharmaceuticals was performed in L-Tyr solution of different concentrations ranging from 0.09 to 7 × 10-6 M. Validation of the device was performed by infrared spectrometry (FT-IR) on three pharmaceuticals from different manufacturers and with different Tyr concentrations.