The formation of α-synuclein peptide (α-syn) oligomers on neural cells is regarded as a pathological hallmark of the onset of Parkinson’s disease. This research focuses on a folding or unfolding process of α-syn under an interfacial environment. We use an approach to provide surface potential required for folding through nanogold colloidal particles. The folded or unfolded conformation of α-syn can be prepared by externally changing the pH to pH 10 or pH 4, respectively. Corresponding the folded or unfolded conformation of the α-syn pre-adsorbed over the gold particles create either dispersed or aggregated condition of gold particles, resulting in a no-shift or red-shift SPR (Surface Plasmon Resonance) band for various sizes of gold colloids. Under 25 <sup>o</sup>C conditions, the reversible self-assembly mechanism was most enhanced over the gold colloidal size of 60 nm, and least over the 10 nm gold colloidal size. When temperature was raised to 55 °C, the reversible self-assembly was enhanced for 10 nm of gold colloidal size. Dissimilarly, the enhancement of the self-assembly was observed for the gold colloidal size of 60 nm as temperature was decreased to 5 <sup>o</sup>C. Our observations regarding nanosize-, pH-, and temperature- dependence confirmed that a plausible oligomeric unit of α-syn constructed over nanogold colloid must be dimer and trimer over 10 nm and 60 nm gold colloidal surfaces, respectively.

Nano size, pH, and temperature dependence of interfacial self-assembly of α-synuclein peptide

249th National Meeting (2015)

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