Satoshi Fujiki

Single lymphocyte analysis with a microwell array chip.

Following genomics and proteomics, cytomics, a novel method of looking at life, has emerged for analyzing large populations of cells on a single‐cell basis with multiple parameters in a quantitative manner. We have developed a highly integrated live‐cell microarray system for analyzing the cellular responses of individual cells using a microwell array chip that has 234,000 microwells each of which is just large enough to fit a single cell. Compared with flow cytometry and microscope‐based methods, our system can analyze the history of the cellular responses of a large number of cells. We have successfully applied the system to analyze human antigen‐specific B‐cells and produced human monoclonal antibodies (MoAb) against hepatitis B virus surface antigen. We have also constructed a mouse system to assess hepatitis B virus‐neutralization activity and have demonstrated the neutralization activity of our antibodies. Our technology should expand the horizons of cell analysis as well as enable generation of human MoAb for antibody‐based therapeutics and diagnosis for infectious diseases such as hepatitis viruses.

Fabrication Technique for Preparing Nanogap Electrodes by Conventional Silicon Processes

A fabrication technique for preparing nanogap electrodes, such as a gold (Au) nano electrode, using conventional silicon (Si) processes–photolithography, etching, thermal oxidation and deposition–is proposed. Stencil substrates are prepared using the Si processes. Then, without requiring complicated technology, nanogap structures can be formed using the technique. Numerous kinds of materials can be selected as an electrode. The mass production of a sensing device for the detection of deoxyribonucleic acid (DNA), or a so-called DNA chip, can be realized at a low cost.

Trapping and Collection of Lymphocytes Using Microspot Array Chip and Magnetic Beads

A microspot array chip, which has microspots of a magnetic thin film patterned on a glass substrate, was fabricated for trapping individual cells and for measuring their cellular response. The chip was easily fabricated by conventional semiconductor fabrication techniques on a mass production level as a disposable medical device. When a solution of lymphocyte-bound-magnetic beads was poured into the magnetized chip, each lymphocyte was trapped on each microspot of the magnetic thin film. The trapped cells were easily recovered from the chip using a micromanipulator. The micro-spot array chip can be utilized for arraying live cells and for measuring the response of each cell. The chip will be useful for preparing on array of different kinds of cells and for analyzing cellular response at the single cell level. The chip will be particularly useful for detecting antigen-specific B-lymphocytes and antigen-specific antibody complementary deoxyribonucleic acid (cDNA).

Synthesis and characterization of high-quality skin-cooling sheets containing thermosensitive poly(N-isopropylacrylamid)

Poly(N-isopropylacrylamide) (PNIPAAm) is the most popular thermosensitive polymer, and exhibits a low critical solution temperature of approximately 32°C. This study aimed to examine the usefulness of new cooling sheets, which are manufactured using a thermosensitive poly(N-isopropylacrylamide) (PNIPAAm) material. We prepared cooling-hydrogel sheets containing PNIPAAm (PNIPAAm sheet). We measured the skin temperature on the arms of the subjects using a thermograph and compared the usefulness of the PNIPAAm sheet and a control cooling-hydrogel sheet that did not contain the PNIPAAm mixture. Thermographic measurements obtained 40 min after the treatment with the cooling sheets showed the skin temperature of the subjects treated with the 3.% (w/w) PNIPAAm sheets to be significantly lower than that of the subjects treated with the control cooling-hydrogel sheet (p < 0.005). Compared with the control sheet, the cooling effect of the new PNIPAAm sheet also persisted for a longer duration (up to 100 min). The PNIPAAm sheets exhibited excellent cooling effects. This sheet may therefore be useful for lowering the body temperature of patients with high-grade fever, such as fever due to influenza infection.