University of Hawaii

Electrical Engineering

Microsystem toward "Body on a chip" AND Surface-Enhanced Raman Spectroscopy using Directionally and Regularly Arrayed Gold Nanoparticle Dimers

Date: 2016-10-05           Add to Google Calendar
Time: 1:30pm - 2:45pm
Location: Holmes Hall 242
Speaker: Osamu Tabata, Professor, Kyoto University and Koji Sugano, Professor, Kobe University

A joint seminar by Prof. Osamu Tabata from Kyoto University and Prof. Koji Sugano from Kobe University.

Microsystem toward "Body on a chip":
Organ-on-chip have a great potential as in vitro human tissue models to accurately emulate human responses to drug candidates. However, the current organ-on-chip technology is still insufficient to reproduce such conditions. This is largely due to the lack of interaction among different organs via a circulation system in a body. To meet with this requirement, microfluidic technology is advantageous to integrate multiple organs and a precise circulation system within a single chip. It enables recreating tissue interactions by medium circulation and evaluating drugs by monitoring multiple organs simultaneously (named body-on-a-chip). Although several efforts have been attempted to develop such a body-on-a-chip, many challenges must be overcome and further innovation is necessary for their realization. In this presentation, our approach of a simplified body-on-a-chip is explained and preliminary assessment result about its potential for a drug testing is demonstrated. In the proposed device fabrication, 3D lithography with the process optimization method is applied to improve the current soft lithography techniques, leading to accurate closed-loop circulation between two types of organs within the device. We also discuss the potential of the fabricated device for a drug testing through in vitro cell-based assay.

Surface-Enhanced Raman Spectroscopy using Directionally and Regularly Arrayed Gold Nanoparticle Dimers:
This talk introduces an ultrasensitive bio/chemical analysis by surface-enhanced Raman spectroscopy (SERS) using directionally arrayed gold nanoparticle dimers. The gold nanoparticle dimer, which has been reported as the highest Raman enhancing structure, was directionally arrayed on a substrate using nanotrench-guided self- assembly. The highest enhancement can be achieved when a particle connection direction of a dimer is matched to polarization direction of incident light. Optimizing the dimer arrangement, 10−11 M limit of detection and 0.3 s rapid detection were achieved using 4,4-bipyridine molecule as a detection molecule. In addition we achieved single molecule detection on the prefabricated substrate for SERS with non-resonant molecules. Single-molecule SERS has never been achieved using the prefabricated SERS substrate. It has been achieved only using molecule bridged particle dimer by in-liquid formation. At 10−5 M, the distribution of Raman intensities were fitted by one Gaussian curve. At 10−11 M, the distribution was fitted by three Gaussian curves. That is consistent with a Poisson distribution. This indicates the probability of detecting 0, 1, and 2 molecule(s). From these results, we confirmed that the developed substrates achieved single molecule SERS detection and identification of the molecule.