Nanobiosensors per a la detecció de contaminants en aigua

Resumen

This thesis aims to develop biosensing tools for environmental monitoring. First, a colorimetric lateral flow biosensor (LFB) has been developed for the detection and quantification of Escherichia coli as a universal fecal indicator. Gold nanoparticles (AuNPs) are used as optical transducers and polyclonal antibodies as the biorecognition elements to capture, tag and indicate the presence of the bacteria. In parallel, a filtration system has been developed to improve the sensitivity of the LFBs. The optimization of the flow properties of the different lateral flow materials has been done by an innovative technique based on the tracking of the flow of the bioluminescent bacteria Aliivibrio fischeri, similar in size and shape to E. coli. Eventually, these LFBs have been tested with river and sewage waters, showing similar sensitivity and good reproducibility and selectivity in all the cases. Second, a bioluminescent toxicity biosensor has been developed for the detection and quantification of pesticides in water samples. In particular, Aliivibrio fischeri, a bioluminescent bacteria, has been used as the biorecognition element and the transducer because it turns up and down bioluminescence according to the concentration of toxic compounds within the water samples. Besides, graphene-oxide (GO) has been used as a non-specific growth enhancer to promote bacterial growth and increase the sensitivity of the system by partially screening the bioluminescence emitted by A. fischeri. The detection and quantification of the bioluminescence has been performed by a smartphone that allows for a cheaper, more user friendly, and portable water toxicity assessment. Third, a smartphone-based portable platform has been developed for the performance of optical sensing, including colorimetric, fluorescent, and bioluminescent assays. This platform has been used to perform and read standard ELISA tests based on colorimetric outputs for human IgG and coronavirus detection. In addition, the system allows for tracking AuNPs aggregation based on the color output of the solution. On the other hand, the platform has been used to detect and quantify quantum dots (QDs) and other fluorescent reporters (i.e. fluorescein), as well as performing fluorescent ELISA tests based on these transducers. Next, the platform allows for bioluminescent readouts with applications in toxicity analysis. Eventually, the platform is suitable for bacteria culture, turbidity measurements, and drug screening for antibiotic resistances assessment.