Polymer Micro Chips for the Analyses of Calcification Risk

Abstract

Calcification is a pathological accumulation of calcium phosphate in soft tissues including blood vessels [1] where it can cause cardiovascular morbidity and mortality e.g. heart attack [2]. Mixing blood serum with supersaturated calcium and phosphate results in colloidal calcium protein particles (CPPs) undergoing a typical ripening process. The conversion time can be optically determined by light scatter measurements of smaller primary and larger secondary CPPs (Fig 1). The half-maximal conversion time T50 is a measure of the calcification risk in the patient. Here we report the miniaturization of the experimental setup on a polymer microchip fabricated by ultrasonic processing. Compared to the usual measurement of light scatter in a nephelometer, the analysis was accelerated by increasing the temperature. Furthermore, better reproducible results were obtained by using a staggered herringbone mixer to mix the reactants [3]. A Peltier element is employed to heat the chip. Using this setup, the analysis was shortened to 16.1 ± 1.1min compared to 279 ± 9min obtained in a nephelometer by increasing the temperature from 38°C to 52°C (Fig. 4).