Smartphone-based analytical devices with optical detection for on-site biosensing: environmental, food and forensic applications

There has been an increasing demand for fast and easy monitoring technologies designed to respond to different analytes. The standard analytical techniques offer accurate and precise results; however, they require clean samples, sophisticated equipment and skilled personnel. For these reasons, they are not suitable for on site, real-time, cost-effective routine monitoring. Biosensors are analytical devices integrating a biological recognition element and a transducer element able to convert the biological response into an easily measurable analytical signal. These tools can easily quantify an analyte or a class of analytes of interest even in a complex matrix, like clinical or environmental samples, thanks to the specificity of the biological components and can be easily implemented in portable devices. The activity carried out during my PhD was mainly focused on the development of different portable paper-based biosensors for multianalyte detection and their implementation into portable analytical devices for point-of-care and point-of-need applications. In particular, enzymes and cells (bacteria and mammalian cell) have been exploited as biorecognition elements, in some cases even by coupling different elements in the same biosensor to increase its robustness. The final goal of biosensors developed was the application in the environmental and forensic fields, since the target analytes are organophosphorus pesticides, heavy metals and molecules with androgenic activity, including new drugs or endocrine disrupting chemicals. Moreover, different optical detection principles (chemiluminescence, bioluminescence, colorimetry) have been exploited and coupled to create an orthogonal detection, which provides more accurate results. Different portable detectors, such as coupled-charged device, smartphone cameras and silicon photomultiplier, and also benchtop laboratory instruments have been used to validate and support the developed biosensors. Several paper-based platforms have been designed and implemented with adaptors and devices fabricated using a dual-extrusion 3D printer to better adapt to the type of assay, reagents, samples and detection method