Bioreceptors for smartphone-based food contaminants detection

Abstract

A bioreceptor is defined as a biological element that specifically recognizes and binds to its ligand. Receptors from natural origin are characterized by their high affinity and selectivity for a target analyte. In the biosensing field, they are generally used to detect molecules in complex matrices such as milk, tissues and vegetable extracts, feed or urine. The classification of the variety of bioreceptors available is based on their chemical and biological nature. Baring this aspect in mind, they are classified in antibodies, enzymes, nucleic acids or emerging biomimetic receptors. Each one presents certain advantages and limitations considering the target analyte, matrix, affinity, stability, cost or even sensing principle. Bioreceptors became relevant in the food safety field due to their capabilities to identify a wide variety of harmful substances in nutritional matrixes in short periods of time. Also, food sources need to undergo strict regulatory controls to ensure quality and safety for consumers. Nowadays, conventional confirmatory techniques (e.g., chromatographic methods) are based on long sample preparation protocols and therefore, are not suitable for fast and high-throughput analysis. Furthermore, they are generally performed by trained personnel and require expensive equipment. On the other hand, screening biosensing platforms have emerged as alternative tools to process hundreds of samples, with reduced costs and analysis time. Gold standard methods employ biological elements for recognition of distinct target analytes including enzyme linked immunosorbent assay (ELISA) for antibodies, enzymatic assays or polymerase chain reaction (PCR) and its variants for nucleic acids. The integration of biorecognition elements with miniaturized platforms, e.g., smartphones, extend the possibilities for the development of reliable biosensing platforms. In this work, we provide an overview of the most widely used bioreceptors mainly in the food safety field but also including medical and environmental applications to discuss their implementation over biosensors development with special emphasis on those that make use of smartphone readout.