Presentation Information
[8a-P01-6]Gold nanoparticle-assisted formation of multiple ring-like lysozyme assembly at air/solution interface
〇(M1)Ming-Lung Lau1, Ke-An Kuo1, Mu-En Li1, Keisuke Yuzu1,2, Eri Chatani2, Hiroshi Masuhara1 (1.National Yang Ming Chiao Tung Univ., 2.Kobe Univ.)
Keywords:
Lysozyme,Gold nanoparticle
Optical trapping is typically performed inside the solutions, while we have been studying optical trapping of polystyrene and gold particles at solution interface, where the trapped particles show characteristic assembling structures extending from the focus to its outside area along the interface. Recently we have been extending this optical trapping to protein solution, discovering the formation of a single large lysozyme (Lys) assembly with the submillimeter diameter and 30 µm depth along the solution surface. To design a new optical trapping method with high speed and more easily controllability, here we introduce gold nanoparticle (Au NP) into the Lys solution. It is expected that the surface plasmon resonance and light scattering may enhance and modulate the Lys assembly.
We irradiated a 1064 nm laser onto a supersaturated Lys solution in D2O (375 mg/mL) containing Au NP at air/solution interface. Without Au NP, graduate assembling and its domain expansion is observed (Fig. 1 (B)), while with Au NPs a unique multiple ring-like structure of Lys assembly was observed (Fig. 1 (C)). This step-by-step assembling may result from the sequential trapping of Au NPs. To analyze this behavior, we propose a two-step optical trapping procedure. Initially, a lower power laser (20 mW) was used to trap a single Au NP, then irradiate it with 500 mW. This procedure is shown in Fig. 1 (A), where obtained images are arranged. The Lys assembly gave an outer dark ring accompanied by a smaller, bright inner ring (Fig. 1 (D)). Upon turning off the laser, the bright ring disappeared, and the dark ring shrank. These results will be examined in terms of enhanced optical force and photothermal effects.
We irradiated a 1064 nm laser onto a supersaturated Lys solution in D2O (375 mg/mL) containing Au NP at air/solution interface. Without Au NP, graduate assembling and its domain expansion is observed (Fig. 1 (B)), while with Au NPs a unique multiple ring-like structure of Lys assembly was observed (Fig. 1 (C)). This step-by-step assembling may result from the sequential trapping of Au NPs. To analyze this behavior, we propose a two-step optical trapping procedure. Initially, a lower power laser (20 mW) was used to trap a single Au NP, then irradiate it with 500 mW. This procedure is shown in Fig. 1 (A), where obtained images are arranged. The Lys assembly gave an outer dark ring accompanied by a smaller, bright inner ring (Fig. 1 (D)). Upon turning off the laser, the bright ring disappeared, and the dark ring shrank. These results will be examined in terms of enhanced optical force and photothermal effects.