Hidenobu Aizawa

Detection of deposition rate of plasma-polymerized films by quartz crystal microbalance

Abstract The deposition rates of plasma-polymerized (pp-) films of styrene, pentafluorostyrene, allyl alcohol, allylamine, methacrolein, acrolein, and acrylic acid were determined by the quartz crystal microbalance technique. Using the same polymerization conditions (100 W RF and 100 Pa vapor pressure) for the various monomers, it was found that the deposition rates were proportional to the polymerization time. The deposition rates of pp-styrene, pp-pentafluorostyrene, pp-allyl alcohol and pp-allylamine were independent of the position of the lower electrode in the plasma polymerization equipment. In contrast, the deposition rates of pp-methacrolein, pp-acrolein and pp-acrylic acid were scattered. The average deposition rate of pp-allyl alcohol was 0.42 μg/min. The average deposition rate of pp-styrene was higher by eight times, and that of pp-pentafluorostyrene was higher by 388 times than that of pp-allyl alcohol. The average deposition rate depended on the chemical structure of the monomer, giving rise to different mechanisms of polymerization. The deposition rates of monomers containing allylic hydrogens were slow due to radical–radical coupling. These unexpected but significant differences were assumed to have arisen from initiation-controlled free radical polymerization.

Turning of contact angle on glass plates coated with plasma-polymerized styrene, allylamine and acrylic acid

Plasma polymerization of styrene, allylamine and acrylic acid was performed under nine polymerization conditions. The obtained polymers generated the film-state only under these conditions. Over 90 days, the contact angles of plasma-polymerized (pp)-films were measured on glass plates coated with pp-styrene, pp-allylamine and pp-acrylic acid. The values of the contact angles of pp-styrene, pp-allylamine and pp-acrylic acid were scattered at the initial stage under the nine polymerization conditions. However, the contact angles of these films after 40 days of storage under vacuum condition always converged into one value. These converged values of contact angles were about 87° for pp-styrene, 67° for pp-allylamine and 28° for pp-acrylic acid. We assumed that this environmental adaptability of contact angle came from the turnover of the polar functional groups between the polymer surface and bulk.

Conventional diagnosis of C-reactive protein in serum using latex piezoelectric immunoassay

Abstract We constructed an integrated immunosensor system to combine a quartz crystal microbalance with the agglutination reaction of immunized latex beads. C-reactive protein (CRP) induced an immunoreaction due to the latex beads with anti-CRP antibody. We succeeded in measuring the concentration of CRP in the human serum as CRP Sensor II.

Rapid diagnosis of Treponema pallidum in serum using latex piezoelectric immunoassay

We developed a conventional immunosensor of Treponema pallidum (TP) using a quartz crystal microbalance (QCM). A QCM is able to measure an agglutination of TP due to TP antigen-immobilized latex particles within 10 min.

Conventional diagnosis of Treponema pallidum in serum using latex piezoelectric immunoassay

We developed a conventional immunosensor for Treponema pallidum (TP) to combine quartz crystal microbalance (QCM) with the agglutination reaction of immunized latex beads. TP induced an immunoreaction due to treponemal antigen-immobilized latex particles. We succeeded in measuring the concentration of TP in the human serum within 10 min by QCM method.

Environmental immunosensor detection for 2,4-dinitrophenol as a model compound of dioxin

We present the detection of 2,4-dinitrophenol (DNP) as a model compound of dioxin to use the competitive reaction between DNP and DNP-conjugated albumin via anti-DNP antibody immobilized quartz crystal microbalance (QCM). The present QCM method is detectable in the range 0.01 to 100 ng/mL of DNP concentration, and linear correlation is obtained from 1 to 100 ng/mL of DNP concentration.

Latex piezoelectric immunoassay: it's application for clinical and environmental analysis

Latex piezoelectric immunoassay (LPEIA) is a new immunoassay method that requires no immobilization of antigen or antibody on the electrode surface of quartz crystal, in contrast to previous immunoassays in which a piezoelectric crystal is used as a microbalance and immobilization is essential. The frequency change was observed during the aggregation of antibody- or antigen-coated latex particles. This method was used for the detection and is sufficiently sensitive for clinical applications. We made a prototype LPEIA sensor for remote sensing and diagnosis to care for a handicapped person in their home.