Recent advances in nanomaterial‐assisted electrochemical sensors for food safety analysis

A flexible glove-based electrochemical biosensor with highly stretchable printed electrode system has been developed as a wearable point-of-use screening tool for defense and food security applications. This disposable-mechanically robust "lab-on-a-glove" integrates a stretchable printable enzyme-based biosensing system and active surface for swipe sampling on different fingers, and is coupled with a compact electronic interface for electrochemical detection and real-time wireless data transmission to a smartphone device. Stress-enduring inks are used to print the electrode system and the long serpentine connections to the wireless electronic interface. Dynamic mechanical deformation, bending, and stretching studies illustrate the resilience and compliance of the printed traces against extreme mechanical deformations expected for such on-glove sampling/sensing operation. An organophosphorus hydrolase (OPH)-based biosensor system on the index finger enables rapid on-site detection of organophosphate (OP) nerve-agent compounds on suspicious surfaces and agricultural products following their swipe collection on the thumb finger. The new wireless glove-based biosensor system offers considerable promise for field screening of OP nerve-agents and pesticides in defense and food-safety applications, with significant speed and cost advantages. Such "lab-on-a-glove" demonstration opens the area of flexible wearable sensors to future on-the-hand multiplexed chemical detection in diverse fields.

The nanomaterials with enzyme-like catalytic activity, named as nanozymes, have aroused wide research interest owing to their striking merits. Metal-organic frameworks (MOFs) have showed great prospect in the construction of novel nanozymes. In this review, firstly, we summarize the most recent contributions in the design construction of the MOFs-based nanozymes. Then, we concentrate our attention on their applications in the fields of sensing and cancer therapies. According to the design strategies, we categorized MOFs-based nanozymes into four classes for review (i.e. pristine MOFs, MOFs with modification, MOFs-based nanocomposites, and MOF derivatives). Meanwhile, the emerging and fascinating 2D MOFs-based nanozymes were also reviewed. A variety of novel applications are also discussed, including nanozymes catalytic mediated signal amplification in sensing applications (e.g. colorimetric sensing, fluorescent sensing, chemiluminescent sensing, electrochemical sensing, and surface-enhanced Raman scattering (SERS)), and nanozymes catalytic mediated cancer therapy (i.e. cancer-starvation therapy, enhancing photodynamic therapy, and cancer-starvation and PDT synergistic therapy). At the end of the article, future opportunities and challenges in this promising research area are tentatively proposed.