ナノポアを利用したウイルスの電気物性評価とウイルスセンサーへの展開

2015 Fiscal Year Annual Research Report

• Project/Area Number: 15H06205
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: 楊 路 東京工業大学, 理工学研究科, 産学官連携研究員 (60757392)
• Project Period (FY): 2015-08-28 – 2017-03-31
• Keywords: バイオセンシング / ウイルス

Outline of Annual Research Achievements

It is considerably vital to quantify individual viral particles in many fields, such as virology, diagnostic, medicine, and so forth. This study aims to develop an efficient sensing method based both on physical and electrical properties of viruses to realize comprehensive, long-term and continuous monitoring of viruses that are widespread in our surrounding environment. Our work is divided into two parts. First, physical properties of viruses, such as size distribution, total particle concentration and zeta potential, will be measured on a particle-by-particle basis with Tunable Resistive Pulse Sensing (TRPS) technology. Then, electrical properties of viruses, including conductivity and permittivity, will be determined by their impedance spectroscopy. Combining these physical and electrical properties, a database related to characteristics of viral particles is expected to be established to discriminate between different viruses.
We concentrated on the first part of our proposal last year. The baculovirus, tobacco mosaic virus and bacteriophage were chosen as representative viral samples. First, the size distributions were obtained, from which the shape information was also extracted. Then, the total particle concentrations were determined, which provided important supplementary information to those infectious titer results. Additionally, the zeta potential reported to be inadequate was measured as well. These preliminary results enabled us to access the basic and in-depth characteristics of various viral particles.

Current Status of Research Progress

3: Progress in research has been slightly delayed.

Reason

Overall, our work is slightly behind the schedule due to two main reasons. The first problem is limited source of getting viral samples. We were supposed to detect as many viruses of interest as possible. However, the current samples used in our experiments are provided generously by collaborative research groups dealing with specific viruses. More diverse viruses need to be further analyzed. Another unexpected thing is that we were in trouble with TRPS device which was out of order. Unfortunately, these problems severely delayed our progress.

Strategy for Future Research Activity

For our future work, measurements of electrical properties of viral particles will be carried out utilizing impedance spectroscopy technology. Specifically, a sophisticated nanochannel equipped with microelectrodes, which allows only one viral particle to pass through the channel and to be detected, will be designed and fabricated. Then, the impedance of viral samples under a wide range of AC voltage and frequency will be recorded, and a model consisting of electrical parameters will be created based on the specific structures of viral particles. By fitting this model with experimental results, the conductivity and permittivity of single viral particle can be estimated. Combining these properties, it is possible to construct a database that is capable of distinguishing between various viruses.
Additionally, the remainder of TRPS measurements will be completed as well. Several measures have been implemented to overcome the aforementioned problems. For instance, we have tried to purchase viruses from commercial organizations, and contacted the qNano distributor to fix the device.
Finally, the recent research has proved that it is accurate enough to measure bioanalytes’ size or concentration with TRPS, and the data from TRPS no longer needs to be verified alongside DLS, TEM, or other technologies. Therefore, we decided to search for the information from some references instead of conducting those measurements by ourselves to make comparison between our results and other studies, ensuring the feasibility of TRPS.