Development of a paper-immobilized yeast biosensor for the detection of physiological concentrations of doxycycline in technology-limited settings

To combat pharmaceutical counterfeiting and antibiotic resistance in low- and middle-income countries (LMIC), there is a need for improved low-cost, portable methods that monitor pharmaceutical concentrations relevant to dosage forms and physiological fluids. To address this problem, we turned to paper analytical devices (PADs), and have recently extended this technology by incorporating whole cell yeast biosensors into PADs to create biological paper analytical devices (bioPADs). The goals of the work presented here were to build on our initial bioPAD technology by showing that fluorescence can be used as a read-out and that the yeast-based system can function in complex matrices. More specifically, we embedded the bioengineered yeast on a paper test strip and showed that this simple biosensor can detect physiologically relevant concentrations of doxycycline in both human urine and raw bovine serum. In this work we also manufactured an inexpensive and portable device capable of reading the fluorescent signal of the bioPAD. This work demonstrates the untapped potential of fluorescent yeast biosensors for use in LMICs.