Synthetic biology approach for point-of-care device applications of biosensors

Abstract

Synthetic biology has broadened the scope of detection tool alternatives, among which whole-cell biosensors and cell-free programmable riboregulators are straightforward, inexpensive to develop and easily implementable to fast-screening point-of-care devices. While considered as more convenient, reliable and low-cost alternatives to traditional detection and monitoring methods, the transfer rate of cellular bio-sensing devices to real life applications has been relatively slow. With the aim of precisely identifying and integrating multiple signals from environmental and serum samples, a series of whole-cell biosensors that respond to heavy metals including copper, lead, cadmium and arsenic were developed in Escherichia coli host. After characterization of single analyte biosensors, synthetic biology strategies such as promoter engineering and coupling with a genetic amplifier are used to enhance detection time and dynamic range for the signal output. Heavy metal bio-recognition modules were designed to produce different output molecules to employ multiplexed sensing where simultaneous detection of multiple molecules is needed for fast-screening. In addition, a novel attempt for transforming these bio-sensing systems to a point-of-care device has been investigated. Thorough functional biofilm amyloid protein and cellulose interactions, immobilization of whole-cell biosensors on a low-cost, easy-storage and portable paper-based platform has been aspired to attain more widespread application globally. Secondly, SARS-CoV-2 is a human pathogen and the main cause of COVID-19 disease, announced as a global pandemic by the World Health Organization. COVID-19 is characterized by severe conditions and early diagnosis can make dramatic changes for both personal and public health. Low cost, easy-to-use diagnostic capabilities can have a very critical role to control the transmission of the disease. Here, a state-of-the-art diagnostic tool was developed with in vitro synthetic biology approach by employing engineered de novo riboregulators. Our design coupled with a home-made point-of-care device can detect and report the presence of SARS-CoV-2 specific genes. The presence of SARS-CoV-2 related genes triggers translation of sfGFP mRNAs, resulting in green fluorescence output. The approach proposed here has the potential of being a game changer in SARS-COV-2 diagnostics by providing an easy-to-run, low-cost-demanding diagnostic capability. Overall, point-of-care device applications of both whole-cell and cell-free biosensor systems have been developed for distinct applications of sensing analytes and nucleic acids.