Piezoelectric immunosensors for urine specimens of Chlamydia trachomatis employing quartz crystal microbalance microgravimetric analyses.

The assembly of a biosensor for Chlamydia trachomatis based on the microgravimetric quartz crystal microbalance (QCM) analysis of the bacteria association to an antibody-functionalized electrode is described. The sensing interfaces consist of a primary cystamine monolayer assembled onto Au electrodes associated with the quartz crystal. The monolayer is further modified with sulfosuccinylimidyl 4-(p-maleimidophenyl)butyrate (sulfo-SMPB) and the goat IgG-anti-mouse IgG Fc-specific Ab or the fragmented F(ab')2 anti-mouse IgG Ab that act as sublayers for the association of the sensor-active anti-C. trachomatis LPS-Ab. Bacteria in the concentration range from 260 ng.mL-1 to 7.8 micrograms.mL-1 are sensed by the functionalized crystals. The association of C. trachomatis to the sensing interface can be confirmed and amplified via interaction of the crystal with various anti-C. trachomatis antibodies. Urine-pretreated functionalized quartz crystals are applied in the analysis of C. trachomatis in urine samples. The sensitivity limits of the electrodes for sensing the bacteria in urine samples corresponds to approximately 260 ng.mL-1. The functionalized crystals assembled via association of anti-C. trachomatis LPS-Ab to the fragmented F(ab')2 anti-mouse IgG Ab reveal long-term stability upon storage at 4 degrees C.