15:30 〜 15:45
▲ [12p-N107-8] Optically Evolved Condensation of Lysozyme Study by Raman Microspectroscopy
キーワード：Optical Trapping, Raman microscopy, Liquid-liquid phase separation
We have been studying on optical trapping of assembling of polystyrene (PS) nanoparticles (NPs) and crystallization of amino acids at solution surface. All the assemblies expand along the surface from the focal point (~ 1 µm) reaching a few tens μm. It was directly confirmed that all behaviors are initiated by optical force. We call those phenomena “Optically Evolved Assembling”, which never happen inside bulk solution. In previous work, we reported the formation of a highly concentrated lysozyme domain. Here we clarify how lysozyme are gathered and distributed starting from solution surface.
The cooperative optical trapping of PS microparticles (MPs) with lysozyme was carried out, which enables us to monitor the optical trapping induced highly concentrated lysozyme domain. Upon switching the trapping laser on, lysozyme molecules are attracted to the focus. The highly concentrated lysozyme domain is formed and its volume expands both laterally and axially. PS MPs are also attracted toward the focus point at the surface, however they did not penetrate into the lysozyme domain. Instead, the linear assembly of PS MPs grew along the edge of the lysozyme domain. We performed Raman microspectroscopy of lysozyme using a 532 nm laser as the excitation beam, before, during, and after the optical trapping of lysozyme. The measurements were carried out at the radial positions far from the trapping laser focus. The integrated intensity 1334 cm-1 (assigned to deformation motion of -CH2 and -CH3 groups) is enhanced with irradiation time and with shorter radial distance dependence fashion. After switching off the irradiation, the intensity came back to the original. In conclusion, the highly concentrated lysozyme domain is inhomogeneous and has a concentration gradient, which may be a precursor state of liquid-liquid phase separation.
The cooperative optical trapping of PS microparticles (MPs) with lysozyme was carried out, which enables us to monitor the optical trapping induced highly concentrated lysozyme domain. Upon switching the trapping laser on, lysozyme molecules are attracted to the focus. The highly concentrated lysozyme domain is formed and its volume expands both laterally and axially. PS MPs are also attracted toward the focus point at the surface, however they did not penetrate into the lysozyme domain. Instead, the linear assembly of PS MPs grew along the edge of the lysozyme domain. We performed Raman microspectroscopy of lysozyme using a 532 nm laser as the excitation beam, before, during, and after the optical trapping of lysozyme. The measurements were carried out at the radial positions far from the trapping laser focus. The integrated intensity 1334 cm-1 (assigned to deformation motion of -CH2 and -CH3 groups) is enhanced with irradiation time and with shorter radial distance dependence fashion. After switching off the irradiation, the intensity came back to the original. In conclusion, the highly concentrated lysozyme domain is inhomogeneous and has a concentration gradient, which may be a precursor state of liquid-liquid phase separation.