Safety of food is a scientific domain requiring advanced handling, preparation, and storage. Food is a paramount need for growth of microorganisms it serves as a medium for proliferation and contamination. The primary historical techniques for food analysis are time-consuming and laborious whereas biosensors have an easier control over these limitations. Biosensor technology is a powerful tool for food analysis. Optical sensors reveal higher calibre for analysis of drugs, pesticide residues, pathogens, heavy metals, toxic substances as well as for overall hygiene monitoring in the food system. Label-free operations altogether acquired a well-established need for the characterization and identification of molecular components. We review the recent advances in label-free optical biosensors based on the target analytes. This study focuses on the concise classification, underlying principles on the optical transducer, optical (surface) analytical techniques as a part of biosensing and use of nanostructures in optical sensors. The main highlights include characterisation of localized surface plasmon and surface plasmon resonance based biosensors. Additionally, other optical biosensors such as bioluminescent optical fibre biosensors, evanescent wave fluorescence, ellipsometric, surface-enhanced Raman scattering and light-addressable potentiometric sensors are also well explained and characterized for food and environmental applications.

Label-free optical biosensors for food and biological sensor applications

Review—Recent Progress in Portable Fluorescence Sensors

A review on photodegradation of organic pollutants using spinel oxide

Carbon nanostructures like graphene and carbon nanotubes are promising components for biosensor transducers because of the high sensitivity of their properties to changes in the environment. One of the most auspicious applications where carbon nanostructures demonstrate an active growth of research interest is food analysis. The unique physical and chemical properties of graphene, as well as carbon nanotubes, warrant their multimodal application potential. The high specific surface area and catalytic activity are utilized for the extraction of analytes from food samples. In addition to their high absorption ability, their high conductivity contributes to the performance efficacy of the electrodes. The main application of carbon nanostructures is expected in constitution of transducing elements of biosensors due to their inherent high modulation capabilities of physico-chemical properties upon exposure to different analytes, and their stability under harsh chemical conditions. They have been utilized as transducers in biosensing platforms such as electrochemical, optical, chemoresistive and field effect transistor-based biosensors for detection of various analytes in food. In this review, we discuss the current state-of-the-art of graphene and carbon nanotube applications in the sensors for food analysis. We summarize the recent progress in using carbon nanostructures for detection of chemical contaminants in food, and the principles of operation, and discuss the perspectives of developing portable devices for rapid in-field analysis.

Graphene-based biosensors for on-site detection of contaminants in food

Dual aptamer assay for detection of Acinetobacter baumannii on an electromagnetically-driven microfluidic platform.

This study examined the applications of chemical sensing devices integrated with LEDs in the range between UV and IR (247–3800 nm). These chemical sensors are used to detect heavy metals, toxins and toxic gases, environmental nutrients, as well as biochemicals and biohazard related compounds. The possible shortcomings of some reviewed applications are discussed, with suggestions or likely resolutions provided. Orange, yellow, and green LEDs, which are less used in other scientific studies, are found to prevail in sensing device applications. A table that includes the findings covered in this paper has been compiled to list some common types of LEDs and their respective uses in the areas of interest. As the fifth paper of a series that discuss LEDs' applications in scientific researches, this review leads to the conclusion that LEDs have become the prominent light sources of chemical sensors and are well qualified to succeed its more energy demanding counterparts in and beyond the reviewed areas.

Chin-Hai Lee

Papers

Applications of LEDs in optical sensors and chemical sensing device for detection of biochemicals, heavy metals, and environmental nutrients