Developing Nanoparticle-Based Platforms for Applications in Nanosensing and Bioanalyses

Abstract

Fundamental understanding of biological systems requires elucidation of biological pathways and processes that can then be exploited to advance new approaches to treat and diagnose diseases. Continuous development of new analytical tools (e.g. biosensors) with enhanced sensitivity and selectivity with spatial and temporal resolution is important to better probe biological systems. Ideal sensor platforms should offer minimal perturbation and be unimpaired by the biological system being probed. Nanoparticle-based platforms offer advantages in sensor technologies, including miniaturization, compartmentalization for multifunctionality, high surface-to-volume ratio, and amenability to surface modification. The work presented in this dissertation describes efforts in fabrication and functionalization of polystyrene-core silica-shell nanoparticles for applications in radioisotope-sensing and O2-sensing. Scintillant-doped polystyrene-core silica-shell nanoparticles (nanoSPA) were prepared and functionalized with various recognition elements for applications in scintillation proximity assay (SPA). In model systems, nanoSPA showed enhanced scintillation response due to binding but suffered from non-specific adsorption. Phospholipid coating was subsequently used to minimize non-specific adsorption and to facilitate insertion of membrane-based receptors. Model binding systems were used to investigate the utility of phospholipid-coated nanoSPA for studying ligand-receptor interactions in a simple separation-free format. GM1-doped phospholipid-coated nanoSPA was also applied in a competitive binding assay to quantify CTB in a complex shrimp extract matrix. The polystyrene-core silica-shell nanoparticle architecture was subsequently used to prepare O2-responsive core-shell nanoparticles (OxyReCS) for O2 detection. OxyReCS were doped with O2-sensitive dye and reference dye for ratiometric measurement of intracellular O2. The in vitro response of OxyReCS was characterized. OxyReCS were introduced into INS-1 cells and were used to measure intracellular O2 consumption in hypoxic conditions. O2 consumption of other metabolic pathways may be monitored with OxyReCS to expand the utility of the platform.