講演情報
[20p-A601-8]Multilayer Assembly Formation of Protein at Solution Surface upon Sequential Optical Trapping of Gold Nanoparticles
〇Hiroshi Masuhara1, Ke-An Kuo1, Chih-Hao Huang1, Po-Wei Yi1 (1.National Yang Ming Chiao Tung University)
キーワード：
optical trapping、protein assembly、gold nanoparticles
We have been exploring new optical trapping phenomena of protein and nanoparticle (NP) at solution interface and elucidating their dynamics and mechanism.1 Previously, lysozyme (Lys) assembly of a sub-milliliter size was demonstrated to be formed, extending from the laser focus to the outside in a radial fashion along the interface.2,3 Despite the optical force, photothermal heating due to the trapping laser is considered to induce concentration increase and phase transition of protein. In this work, we present a novel trapping phenomenon of Lys by adding Au NPs and examining the induced assembly dynamics.
We study a super-saturated solution of 375 mg/mL Lys in D2O by adding 200 nm Au NPs as a heat source due to its high photothermal conversion efficiency. The 1064 nm trapping laser of 1 W is focused at the air/D2O interface, where transmission and fluorescence imaging are carried out. Without Au NPs Lys assembly slowly expands two-dimensionally along the interface upon trapping laser irradiation, while a unique behavior is observed by adding the Au NP. As shown in Figure 1A, concentric layers are sequentially formed in an assembly that arises from the sequential arrival of Au NPs which are pumped up from the bottom to the surface by the trapping laser. The timing of new layer formation at the outside matches with the arrival of next Au NP. Concentration distribution of lysozyme is visualized using scanning confocal fluorescence imaging as in Figure 1B. A highly concentrated area is rapidly formed, while its central intensity distribution is flat. The assembly formation is not simply ascribed to photo thermal heating effect by the Au NPs but may be coupled with local concentration increase and saturation of Lys.
We study a super-saturated solution of 375 mg/mL Lys in D2O by adding 200 nm Au NPs as a heat source due to its high photothermal conversion efficiency. The 1064 nm trapping laser of 1 W is focused at the air/D2O interface, where transmission and fluorescence imaging are carried out. Without Au NPs Lys assembly slowly expands two-dimensionally along the interface upon trapping laser irradiation, while a unique behavior is observed by adding the Au NP. As shown in Figure 1A, concentric layers are sequentially formed in an assembly that arises from the sequential arrival of Au NPs which are pumped up from the bottom to the surface by the trapping laser. The timing of new layer formation at the outside matches with the arrival of next Au NP. Concentration distribution of lysozyme is visualized using scanning confocal fluorescence imaging as in Figure 1B. A highly concentrated area is rapidly formed, while its central intensity distribution is flat. The assembly formation is not simply ascribed to photo thermal heating effect by the Au NPs but may be coupled with local concentration increase and saturation of Lys.