Aptamer-Based Microcantilever Biosensors for Label-Free PSA Detection

The single-ended clamped microcantilever biosensors and qual-ended clamped with serpentine cantilevers microcantilever biosensors were developed and batch-fabricated using micro-electromechanical system technology for accurately measuring prostate-specific antigen (PSA) via a laser emitted by the confocal fiber displacement sensor. The aptamer was immobilized on the gold surface of the sensing cantilever, so that interactions between the aptamer and PSA successfully generated a stress change of the microcantilever biosensors, resulting in a bending conformation. The reference cantilever without gold eliminates interference from the environment by detecting deflection induced by nonspecific interactions. The profile of microcantilevers could be monitored by a spectral confocal 3-D morphological scanning and imaging system. The two microcantilever deflections had a good linearity within 50-2000 ng/mL. The detection limits of the two microcantilever are 9.88 and 7.08 ng/mL, respectively. These microcantilever biosensors provide a promising approach to detect PSA in early prostate cancer (PCa) diagnosis.