Detection of galactosyltransferase using chemically modified piezoelectric quartz

Biosensors: a viable monitoring technology?

Biosensors for practical in vivo and in vitro applications are dependent on the effective integration of several biological and physical technologies. This review paper was stimulated by an IEE seminar. Some of the more recent advances aimed at taking techniques of fundamental and academic interest to various forms of practical reagentless biochemical analysis are highlighted, with associated clinical and commercial consequences. The paper describes some of the most recent developments in biosensor research, in particular those relating to material aspects of fabrication, including multilayer films for sensor applications, advances in ISFETs, conjugated polymers, new developments in quartz crystal based biosensors, as well as advances in amperometric enzyme electrodes and the application of devices for continuous monitoring.

Determination of immunoglobulin M concentration by piezoelectric crystal immunobiosensor coated with protamine

In the present study, the specific binding between protamine and immunoglobulin M (IgM) has been exploited to construct a piezoelectric crystal based immunobiosensor for the determination of concentration of IgM. The system consisted of highly stable IC based oscillator, 8-digit frequency counter and modified piezoelectric crystal device. The crystal surface was physically modified and chemically treated (refluxed) with strong acid to produce stable hydroxylic groups of silicon oxide. This modified surface reacted strongly with coupling reagents for binding of protein molecules. The protamine was immobilized by using either gamma-aminopropyltriethoxy silane (gamma-APTES) or 2.2.2-trifluoroethanesulfonyl chloride (tresyl chloride). Scanning electron microscope images of piezo crystal revealed that tresyl activated surface presented more surface area for binding than gamma-APTES modified surface and showed better sensitivity. This immobilization technique also improved the reproducibility and long term stability of the detection system. Using the system described, the IgM concentration up to the level of 10 ng/ml could be detected without interference of IgG.