Abstract

The expanding role of metal-organic frameworks (MOFs) for the recognition of hazardous materials can be assigned to their numerous intriguing properties. Some unique characteristics of MOFs include dynamic porosity, high pore volume, tailorable optical properties, myriad of functionalities, and open metal sites. Besides, MOFs can harbor various guest molecules (e.g., metal nanoparticles, proteins, enzymes, and so on) both at their surface and within their pores. The above-mentioned properties of MOFs justify their expanding role in sensing applications. Accordingly, this work elaborates about the recent progress in the sensing applications of MOFs with specific focus on organophosphate pesticides (OPPs). Specifically, for OPPs sensing, acetylcholinesterase (AChE) was encapsulated in zeolitic imidazolate framework (ZIF)-8 to yield a nanoreactor (NR) termed as AChE@ZIF-8 NR. This NR produces a characteristic yellow color upon hydrolysis of acetylthiocholine chloride (ATCh) under optimized conditions of pH, temperature, and substrate concentration. The colorimetric biosensing of OPPs (e.g., malathion, glyphosate) was based upon their suppressive action on the ATCh hydrolysis activity of the NR. As a result, the intensity of the yellow color produced during ATCh hydrolysis by the NR is substantially reduced. Overall, the NR exhibited excellent reproducibility, stability, and ease of detection of the OPPs inhibitory colorimetric response.