Date of Award

5-2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Chemistry

Committee Member

Dr. Jason McNeill, Committee Chair

Committee Member

Dr. Julia Brumaghim

Committee Member

Dr. Steven Stuart

Abstract

Conjugated polymer nanoparticles (CPNs) or "polydots" are among the most promising fluorescent nanoparticle probes for many fluorescence-based techniques used in biological analysis as a result of their small size, large absorption cross-sections, tunable emission wavelengths and high fluorescence quantum yields. For this reason, various fluorescence-based applications are being pursued such as particle tracking and single nanoparticle sensors. Some applications require or could benefit from narrower particle size distributions, and there is also interest in the dependence of particle properties on size. Thus there is interest in developing and improving methods for separating conjugated polymer nanoparticles by size. This dissertation is focused on using the agarose gel electrophoresis technique for size separation of CPNs. The nanoparticles used in this study are made from three conjugated polymers which are PFBT, MEH-CN-PPV, and MEH-PPV. In order to study the effect of particle sizes on energy transfer in CPNs, perylene red doped PFBT particles with various doping ratios are also utilized. In this work, UV-Vis absorption, fluorescence emission and single molecule fluorescence microscopy and spectroscopy are used to study the photophysical properties of CPNs. Moreover, to study the size distribution, zeta potential and surface morphology of the nanoparticles, techniques such as dynamic light scattering (DLS) and atomic force microscopy (AFM) were applied. Different methods were tested to extract the nanoparticles from the agarose gel after the size separation and it was found out that among these methods, mini electrolysis extraction works the best for the case of CPNs. This work shows that by setting appropriate parameters such as gel concentration, electric field strength, gel passivation, etc., agarose gel electrophoresis is an appropriate technique for size separation of CPNs. Moreover, by having suitable methods for particle extraction from the gel after running electrophoresis experiment, the possibility of having samples of CPNs with a narrow size distribution which be used to study the size-dependent properties of CPNs is provided.

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