Seogil Oh

Mesoporous silica thin films as a spatially extended probe of interfacial electric fields for amplified signal transduction in surface plasmon resonance spectroscopy

A new simpler concept about the signal amplification of surface plasmon resonance (SPR) that is based on the utilization of mesoporous silica thin films is demonstrated. As compared to monolayer based coatings, mesoporous silica thin films of approximately 200 nm extend the interaction arena away from the metal, thus permitting the integration of the change in optical contrast at different distances from the sensor surface.

Investigation of adsorption behavior of bisphenol A on well fabricated organic surfaces using surface plasmon resonance spectroscopy.

Molecular adsorption of bisphenol A (BPA) on three types of self-assembled monolayers with different functionalities, such as -CH3, -SH, and -COOH, was examined using surface plasmon resonance (SPR) spectroscopy. BPA molecules in an aqueous solution were easily adsorbed onto a hydrophobic surface compared to a hydrophilic surface. Sorption behavior of BPA into poly(2-methoxyethyl acrylate) (PMEA) layer, which is known as a biocompatible polymer, was also investigated. Sorption and desorption dynamics of BPA into PMEA were found to be very rapid and quite reversible. The swelling of PMEA by sorption of BPA results in the change in SPR angle and allows one to quantify the BPA concentration below 100 ppm. In addition, the transport mechanism of BPA within the membrane of organ can be inferred by the experimental results.

pH-triggered ionization of self-assembled monolayers investigated byin-situ surface plasmon resonance measurements

Self-assembled monolayers (SAMs) of 2-aminoethanethiolhydrochloride (AET) or 2-aminoethanethiol-hydrochloride (AHT) were formed on gold substrate. Deprotonation and reprotonation of SAMs of AET and AHT on gold substrate were investigated by using time-resolved surface plasmon resonance (SPR) measurements. The changes of the terminal functional groups from -NH3+Cl-to -NH2 (vice versa) via the HCl and NaOH treatment were successfully detected, based on the fact that the initially formed AET and AHT SAMs were assumed to be a zwitterion-like species,-NH3+Cl-.