Electrochemical immunosensors have attracted immense attention due to the ease of mass electrode production and the high compatibility of the miniature electric reader, which is beneficial for developing point-of-care diagnostic devices. Electrochemical immunosensors can be divided into label-free and label-based sensing strategies equipped with potentiometric, amperometric, voltammetric, or impedimetric detectors. Emerging nanomaterials are frequently used on electrochemical immunosensors as a highly rough and conductive interface of the electrodes or on nanocarriers of immobilizing capture antibodies, electroactive mediators, or catalyzers. Adopting nanomaterials can increase immunosensor characteristics with lower detection limits and better sensitivity. Recent research has shown innovative immobilization procedures of nanomaterials which meet the requirements of different electrochemical immunosensors. This review discusses the past five years of advances in nanomaterials (metal nanoparticles, metal nanostructures, carbon nanotubes, and graphene) integrated into the electrochemical immunosensor. Furthermore, the new tendency and endeavors of nanomaterial-based electrochemical immunosensors are discussed.

Fast and sensitive detection of foodborne bacteria, such as Salmonella, is essential for food safety and public health control. This study constructed a microfluidic device integrating a top-bottom opposite electrode pair for performing positive dielectrophoresis (pDEP) and electrochemical impedance spectroscopy (EIS). The immunomagnetic beads (IMBs) modified with anti-Salmonella antibodies were spiked in Salmonella enterica serovar Choleraesuis (SC)-containing samples for 30 min to form IMBs@SC complexes, and they were separated by a magnet, which can prevent the sample matrix from contaminating the EIS detectors. After applying the 50 kHz/7.5 V_pp pDEP for 3 min to collect the IMBs@SC complexes in the microholes of the working electrodes, EIS was used to determine the SC concentration. The linear range and the calculated detection limit obtained from SC-spiked undiluted milk samples are 10¹ to 10⁴ and 2 cfu/mL. The total procedures from the IMBs immunoreaction to the sample-to-result on the device only take 50 min. The microfluidic device offers a promising platform for the rapid and ultrasensitive detection of pathogenic bacteria.

An outbreak of foodborne pathogens would cause severe consequences. Detecting and diagnosing foodborne diseases is crucial for food safety, and it is increasingly important to develop fast, sensitive, and cost-effective methods for detecting foodborne pathogens. In contrast to traditional methods, such as medium-based culture, nucleic acid amplification test, and enzyme-linked immunosorbent assay, electrochemical biosensors possess the advantages of simplicity, rapidity, high sensitivity, miniaturization, and low cost, making them ideal for developing pathogen-sensing devices. The biorecognition layer, consisting of recognition elements, such as aptamers, antibodies and bacteriophages, and other biomolecules or polymers, is the most critical component to determine the selectivity, specificity, reproducibility, and lifetime of a biosensor when detecting pathogens in a biosample. Furthermore, nanomaterials have been frequently used to improve electrochemical biosensors for sensitively detecting foodborne pathogens due to their high conductivity, surface-to-volume ratio, and electrocatalytic activity. In this review, we survey the characteristics of biorecognition elements and nanomaterials in constructing electrochemical biosensors applicable for detecting foodborne pathogens during the past five years. As well as the challenges and opportunities of electrochemical biosensors in the application of foodborne pathogen detection are discussed.