Human serum albumin adsorption study on 62-MHz miniaturized quartz gravimetric sensors.
We have designed and fabricated 25-microm-thick quartz resonators operating at a fundamental resonance frequency of approximately 62 MHz. The results show a substantial increase in the mass sensitivity compared to single monolithic commercial resonators operating at lower frequencies in the approximately 5-10-MHz range. The overall performance of the micromachined resonators is demonstrated for the example of human serum albumin protein adsorption from aqueous buffer solutions onto gold electrodes functionalized with self-assembled monolayers. The results show a saturation adsorption frequency change of 6.8 kHz as opposed to 40 Hz for a commercial approximately 5-MHz sensor under identical loading conditions. From the analysis of the adsorption isotherm, the equilibrium adsorption constant of the adsorption of the protein layer was found to be K = 8.03 x 10(6) M(-1), which is in agreement with the values reported in the literature. The high sensitivity of the miniaturized QCM devices can be a significant advantage in both vapor and solution adsorption analyses.
Kao
Ping
P
Department of Electrical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Patwardhan
Ashish
A
Allara
David
D
Tadigadapa
Srinivas
S
D000327:Adsorption; D004566:Electrodes; D006801:Humans; D008722:Methods; D008904:Miniaturization; D011791:Quartz; D012709:Serum Albumin / Q000737:chemistry*
D012709:Serum Albumin; D011791:Quartz