Graduate School of Science, Osaka

TAKUYA IIDA: ’Development of Light-induced Acceleration System for Various Biochemical Reactions Based on Photothermal Fluidics’

A biomolecular recognition is crucial for the high selectivity for the specific detection, and a rapid, highly sensitive and specific detection methods of various nano-biomaterials and microbes (bacteria, viruses etc.) are required in the fields of medical care and food hygiene. There are various types of biomolecular recognitions, for example, DNA double strand formation, antigen-antibody reaction etc., and biomolecule-modified nanoparticles (NPs) as the probe are useful for the control of these processes.

Moreover, the detection efficiency can be dramatically increased if the probe NPs and target biomaterials would be remotely assembled into the observation region. The optical guiding method with laser irradiation is promising for this purpose.

We are developing simulation methods for light-induced nano-dynamics with the unified theory of light-induced force (LIF) exerted on nanomaterials, and the selective assembly of NPs with specific properties and the control of their quantum mechanical properties such as radiative decay rate were predicted and successfully demonstrated in the recent experiment. On the other hand, if probe NPs have high photothermal properties, the light-induced convection (LIC) can be used for the macroscopic transportation. Paying attention to the synergetic effect of such LIF and LIC as the “optical guiding force“, we are trying to develop the methods for the dynamics control of nano-biomaterials and microbes to realize the extremely high performance bio-analysis based on “light-induced biomolecular recognition“.

In this talk, we would like to introduce our challenge in the development of the “light-induced acceleration system (LAC-SYS)“ based on our recent research achievements focusing on three topics as follows: (i) photothermal assembling of biomolecules (pg-level to fg-level proteins and polycrystallization of porphyrin-based molecules), (ii) submillimeter network formation triggered by light-induced hybridization of zmol-level DNA, and (iii) assembling and rapid counting of small amounts of microbes with optical and electric fields. Our trial will pave the way to a next generation smart biophotonics based on “Photothermal Fluidics“.

YASUYUKI YAMAMOTO: ’Photothermal Assembly Dynamics of Small Objects’

Laser heating at the solid-liquid interface can generate a bubble and fluid flow to rapidly assemble dispersoids such as nano-, micro-particles, bacteria and molecules (Photothermal-Fluidics). This phenomenon enables us to colloidal lithography, concentration measurement of small objects and chemical reaction in the local region and so on. In this method, it is required to assemble various dispersoids, that have different constituent materials, size, etc., at an arbitrary place with high efficiency and good reproducibility. However, there is little knowledge on physicochemical mechanism for the highly efficient assembly and the control of assembly dynamics. In this study, focusing on the surface modulation of the bubble with a amphiphilic agent, we have clarified that this process greatly affects assembly dynamics of polystyrene microparticles (PS) and improves assembly efficiency (= the number of assembled PS / total number of PS in the suspension) 10-20 times in comparison with the case of no amphiphilic agent. Furthermore, we revealed the influence of concentration and constituent material of dispersoids (PS and bacteria) on assembly efficiency. These results can extend the limit of measurable concentration by one order and lead to improvement of measurement precision.

Seminar, September 26, 2018, 12:00. ICFO’s Seminar Room

Hosted by Prof. Romain Quidant