Development of Up-Conversion nanoparticle-based portable screening test for in situ diagnosis of infectious diseases

This dissertation is concerned with the development and validation of nanotechnological sensor components and platforms for the diagnosis of A-group beta-hemolytic streptococcus using the lateral flow strip (LFA) method. Streptococcus is a common bacterium found in the human flora, especially in the throat and nose, and is prevalent in rural locations where accurate detection may be challenging. LFA is a rapid, simple, and cost-effective biosensor used for the analysis of various samples at the point of care, making it one of the most common biosensors currently available. The main goal of this thesis is to develop an upconversion nanoparticle-based lateral flow assay (UCNP-LFA) for the rapid detection of A-group beta-hemolytic streptococcus. Surface modification of probes with various polymers and conjugating them with disease-specific antibodies (varying concentration), designing the sensor in which disease-specific antibody traps are imprinted onto a membrane are all necessary steps in the development of Lateral Flow Strip units that is performed in this thesis. In addition, optimization of various buffers that allow flow of disease specific antibody-nanoparticle conjugate through the Nitrocellulose Membrane, and optimization of other strip components such as various types of Nitrocellulose Membrane (with varying pore size), conjugation and sample pads, antibodies dispensing speed were investigated. The developed UCNP-LFA samples were characterized by HR-TEM, SEM, XRD, FTIR, DLS, Zeta potential, Uv-Vis spectroscopy, Fluorescent microscope and PL spectroscopy. The UCNP-LFA tests were evaluated for sensitivity, specificity, accuracy, and achieved a value of 73% , 75%, 74% according to the results, respectively.