| AVS 62nd International Symposium & Exhibition | |
| Biomaterial Interfaces | Tuesday Sessions |
| Session BI-TuP |
| Session: | Biomaterial Interfaces Poster Session |
| Presenter: | Takumi Miyashita, Toyo University, Japan |
| Authors: | T. Miyashita, Toyo University, Japan N. Bessho, Toyo University, Japan T. Okamoto, Riken, Japan H. Vieker, Bielefeld University, Germany A. Beyer, Bielefeld University, Germany A. Gölzhäuser, Bielefeld University, Germany H. Takei, Toyo University, Japan |
| Correspondent: | Click to Email |
Noble metal nanoparticles possess an optical extinction peak due to localized surface plasmon resonance, LSPR. The peak shifts when the refractive index in the immediate vicinity changes, a useful property for making biosensors. While there are numerous ways to prepare noble metal nanostructures, we find that evaporating a noble metal on a surface coated with a monolayer of monodisperse silica nanospheres is a convenient method. With the above method, it is easy to form highly dense nanostructures, with the extinction peak in excess of O.D. 2. The spectrum can be readily modified by varying the sphere diameter and metal deposition thickness. While this method has been used by a number of groups, we found that resulting structures possess not only a peak in the visible but also an additional peak in the near-IR. The latter peak has four times the sensitivity of the peak in the visible.
There are many ways to use LSPR sensors other than the traditional antigen-antibody monitoring. One has to do with improving a colorimetric diagnostic method. Often it is implemented in the form of immunochromatographic assays, ICA. It is, however, used mostly only for qualitative assays, such as detection of flu. We believe that bestowing it with a quantitative detection capability as well as an increased dynamic range would further boast the use of ICAs. In some colorimetric assays, an enzyme is used to generate a colored product. By using the alkaline phosphatase-NBT/BCIP system, here we describe various techniques for maximizing the interaction between the enzymatic reaction product and the sensor surface. Another application is detection of nanoscopic gas bubbles. If bubbles form on the sensor surface, even with the size of 5 nm or less, it should lead to a detectable shift of the peak. We have decided to test this concept on detection of useful microorganisms from soil samples obtained below the ocean bed where very few are expected. Our strategy is to look for catalase which is secreted by practically every life form. When catalase, captured on the sensor, reacts with H2O2, oxygen bubbles form so that the presence of microorganisms can be potentially detected by monitoring bubble formation. Another set of experiment involves monitoring of vascular endothelial cells in the presence of elevated amounts of glucose. We have cultivated VE cells on our LSPR sensor. It is our intention to use the sensor signal for monitoring changes in the morphology of cells induced by glucose, leading to a better understanding of diabetes.