Biophysical Society Thematic Meeting - October 25-30, 2015

Polymers and Self Assembly: From Biology to Nanomaterials Poster Session II

43-POS Board 43 Synthesis, Characterization and Applications of Size Restricted Polycationic Hen Lysozyme Nanoparticles Tulsi Swain .Rajaram Swaminathan, Indian Inst. Tech. Guwahati, Guwahati, Assam, India. We report a novel strategy for synthesis of Hen Egg-White Lysozyme (HEWL) nanoparticles by alkaline pH-induced aggregation at room temperature with subsequent stabilization by intermolecular disulfide bonds [1]. Size heterogeneity of the nanoparticles renders their characterization a formidable challenge. To address this we have used size exclusion and ion exchange chromatography to separate differently sized nanoparticles. Further biophysical methods like steady state fluorescence anisotropy, DLS, TEM, AFM and SAXS were employed to characterize the size-fractionated nanoparticles in detail. Accessible hydrophobic regions in the HEWL nanoparticles were assessed by ANS fluorescence. Pyrene fluorescence sensitivity to solvent polarity has been used to estimate changes in probe microenvironment as a result of conformational change during aggregation of HEWL. Significant drop in steady state anisotropy of fluorescein conjugated fractions clearly shows that aggregates labeled with multiple fluorophores exhibit homo-FRET. Self-quenching of fluorescein limits the brightness available per labeled protein. But in our case the phenomenon of self-quenching is turned into an advantage to study aggregation. The fluorescein conjugated nanoparticles can be used for targeted molecular imaging by attaching appropriate ligands to them. Polycationic HEWL nanoparticles have numerous positive charges on their surface which can facilitate association of polyplexes to various negatively charged cargoes.These nanoparticles were able to condense DNA efficiently as revealed from gel retardation assay. The promising HEWL nanoparticles can be utilized as imaging nanovectors, DNA delivery vehicle and F19 contrast agents. These nanoparticles also offer the advantage of being engineered for use as drug delivery vehicle in future. [1] Ravi VK, Swain T, et. al., (2014) PLoS ONE 9(1): e87256. doi:10.1371/journal.pone.0087256

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