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.

Non-noble metal plasmonic enhanced photoelectrochemical sensing of chlorpyrifos based on 1D TiO2-x/3D nitrogen-doped graphene hydrogel heterostructure

Low-cost and resource-rich non-noble metal plasmonic materials have attracted tremendous attention as potential substitutes for plasmonic noble metals. Herein, 3D nitrogen-doped graphene hydrogels (NGH) decorated with Ti³⁺ self-doped 1D rod-shaped titanium dioxide nanorods (TiO_2-x NR), 10-25 nm in size, were prepared by a facile one-step method. It was found that the as-fabricated TiO_2-x NR/NGH showed a synergistic effect, displaying enhanced photoelectrochemical (PEC) activity by controlling the nanoscale architecture and improving the electronic properties, while also producing abundant oxygen vacancies, which extended the light harvesting and suppressed the recombination of electron-hole pairs induced by the non-noble metal surface plasmon resonance (SPR) effect. In particular, the transient-state photocurrent intensity of the TiO_2-x NR/NGH composites was 5.1 times as high as that of pure TiO₂. Therefore, the TiO_2-x NR/NGH composites could serve as a substrate material for PEC sensing, providing a good basis for selective and sensitive detection of chlorpyrifos. Under optimal conditions, the constructed PEC sensor was found to have several advantages including a broad linear range (0.05 ng/mL-0.5 μg/mL), low detection limit (0.017 ng/mL), and considerable stability, demonstrating that the sensor may offer a promising route in the field of environmental analysis.

Carbon dots-sensitized amorphous MoSx photoanode: Sequential electrodeposition preparation and dual amplified photoelectrochemical aptasensing of adenosine

The design and fabrication of high visible-light activated photoelectrode are essential to precisely detect biomolecule in biological system. Herein, an ultrasensitive photoelectrochemical (PEC) aptasensor for specific recognition of adenosine is established based on carbon dots sensitized-amorphous molybdenum sulfide (a-MoS_x/CDs) photoanode and dual amplification strategy. The heterostructured photoanode achieved by sequential electrodeposition reveals significantly boosted photocurrent with good stability and repeatability under visible light illumination, giving the credit to highly activated visible light absorption, uniform coverage and good electric contact to the underlying substrate, as well as the energy-band alignment between the two components. By stepwisely immobilizing complementary DNA probe (NH₂-DNA) and adenosine aptamer (Apt), followed by methylene blue (MB) binding with the guanine base on Apt, a dual amplified self-powered PEC aptasensor for adenosine detection is constructed. Based on the co-sensitization effect of CDs and MB, ultrasensitive and high-affinitive determination of adenosine is realized over the concentration range of 0.01 nM-1000 nM at 0 V (vs. SCE), with satisfactory stability and reproducibility. The detection limit is as low as 3.3 pM, demonstrating a performance even surpassing most of the sensors reported so far. The prospective application of the co-sensitized a-MoS_x photoanode for ultrasensitive aptasensing is highlighted in this work.

A single-interface photoelectrochemical sensor based on branched TiO2 nanorods@strontium titanate for the detection of two biomarkers

Based on the enhanced photogenerated charge-separation properties of B-TiO₂ NRs@SrTiO₃ heterostructures, a photoelectrochemical sensor for detecting alpha fetoprotein and cancer antigen 153 at a single interface was first established.

A facile synthesis of Fe3O4/nitrogen-doped carbon hybrid nanofibers as a robust peroxidase-like catalyst for the sensitive colorimetric detection of ascorbic acid

We describe a facile synthesis of Fe₃O₄/nitrogen-doped carbon hybrid nanofibers as a robust peroxidase-like catalyst for the sensitive colorimetric detection of ascorbic acid.