Infections acquired from ingesting contaminated food and water poses an adverse effect on public health and safety, thus affecting nations' economy. Technical approaches developed over years have contributed adequately to microbial detection in food and water, yet, unveiling spaces for more improvement on early and rapid detection of pathogens. This review highlights different strategy assessing bio-functionalized inorganic nanoparticles towards the detection of pathogens in food and water samples. Conjugates of several bio-receptors and inorganic nanoparticles showed rapid, real-time, repeatability, and appreciable limit of detection in targeted pathogens. A patent referenced in this study established the biocompatibility of bio-functionalized inorganic nanoparticles mechanism. Unique attributes exhibited by bio-functionalized inorganic nanoparticles showed potential and improvement of the existing bio-sensing pathogen detection methods. Each of the identified strategies described showed a promising pathway accommodating the development of simple, and even the fabrication of low-cost materials for easy detection of bacterial pathogens in food and water products.

Pathogenic bacteria and several biomolecules produced by cells and living organisms are common biological components posing a harmful threat to global health. Several studies have devised methods for the detection of varying pathogenic bacteria and biomolecules in different settings such as food, water, soil, among others. Some of the detection studies highlighting target pathogenic bacteria and biomolecules, mechanisms of detection, colorimetric outputs, and detection limits have been summarized in this review. In the last 2 decades, studies have harnessed various nanotechnology-based methods for the detection of pathogenic bacteria and biomolecules with much attention on functionalization techniques. This review considers the detection mechanisms, colorimetric prowess of bio-receptors and compares the reported detection efficiency for some bio-receptor functionalized nanoparticles. Some studies reported visual, rapid, and high-intensity colorimetric detection of pathogenic bacteria and biomolecules at a very low concentration of the analyte. Other studies reported slight colorimetric detection only with a large concentration of an analyte. The effectiveness of bio-receptor functionalized nanoparticles as detection component varies depending on their selectivity, specificity, and the binding interaction exhibited by nanoparticles, bio-receptor, and analytes to form a bio-sensing complex. It is however important to note that the colorimetric properties of some bio-receptor functionalized nanoparticles have shown strong and brilliant potential for real-time and visual-aided diagnostic results, not only to assess food and water quality but also for environmental monitoring of pathogenic bacteria and a wide array of biomolecules.