Masao Koyama

Liposome immune lysis assay (LILA): a simple method to measure anti-protein antibody using protein antigen-bearing liposomes

A new simple immunoassay technique using immune lysis of liposomes was developed to measure antibody against protein antigens. Multilamellar liposomes were composed of dipalmitoylphosphatidylcholine, cholesterol and phosphatidylethanolamine substituted with the hetero-bifunctional cross-linking reagent N-hydroxysuccinimidyl 3-(2-pyridyldithio)propionate (SPDP). The protein antigen (human IgG) was coupled to these liposomes after treatment with SPDP and mild reduction. As a release marker, carboxyfluorescein (CF) was entrapped in the liposomes. The CF release was specific to anti-human IgG antibody and depended on the presence of complement. This technique could detect 10(-15) mol of anti-human IgG antibody or human IgG. The liposomes were stable over 8 months at 4 degrees C under nitrogen gas.

Improved enzyme sensor for glucose with an ultrafiltration membrane and immobilized glucose oxidase

Abstract A specific enzyme sensor for glucose was constructed by covering an immobilized glucose oxidase membrane on an oxygen electrode with an asymmetric ultra-filtration membrane. The response time is only 10 s, the calibration graph is linear for 3 × lO -6 –2 × lO -3 M glucose, and the sensor can be used repeatedly at room temperature for at least 100 days with little deterioration in response.