Session: 3A

Surfaces and interfaces play important role in biology and medicine since most biological processes are surface related or surface mediated, and measurement techniques which are capable of monitoring biological interfacial processes are of rapidly growing interest. We present a novel quantitative sensing technique based on multiresonant nano-acoustic shear wave biosensor technology for study of interactions of cells with biofunctionalized surfaces. This technique allows rapid measurement of mechanical interfacial properties such as density and complex elastic modulus of biological substances in real time at different depths at nano-scale level. TSM acoustic sensors, which utilize shear motion generated by a vibrating AT-cut quartz resonator structure, have the ability to monitor interfacial phenomena at the sensor/liquid interface. Chondrocyte cells were placed in DMEM solution, which provided appropriate conditions for maintaining cells at the required level of bioactivity. Next, the immobilization process of the chondrocyte cells onto various solid surfaces was characterized. Specifically, the properties of the cells suspended in DMEM buffer and their interaction with a gold and collagen surfaces with modified receptors sites were measured at different physiological conditions. The processes accompanying sedimentation of chondrocyte cells initially uniformly suspended in DMEM buffer were monitored at the fundamental and harmonic frequencies in the frequency range from 5 to 55MHz as a function of time. A sedimentation rate, and different arrangements of the cells at the gold and biofunctionalized collagen surfaces were determined. Specifically, the adhesion period followed by the cell proliferation time were measured, and unique acoustic signatures of the sensor response corresponding to each of these processes were identified. The acoustic responses of the cells were compared with images obtained with optical, SEM and AFM microscopic techniques. In conclusion, multiresonant TSM piezoelectric sensors offer a very attractive technology platform for study various processes involving cells and surfaces in real time with high sensitivity and reproducibility.