Piezoelectric crystal immunosensors based on immobilized fullerene C60-antibodies

Abstract

Fullerene C60-antibodies, e.g., C60-anti-human IgG and C60-anti-hemoglobin (Hb), coated piezoelectric crystals were prepared and applied in piezoelectric quartz crystal immunosensors for human IgG and hemoglobin, respectively. The immobilization of anti-IgG and anti-Hb onto fullerene C60 were studied with a C60-coated piezoelectric crystal detection system. The partially irreversible responses for these antibodies were observed by the desorption study, which implied that C60 could chemically react with these bio-species. Thus, immobilized C60-anti-IgG and C60-anti-Hb coating materials were successfully prepared and identified with FTIR spectrometry. The C60-anti-human IgG and C60-anti-Hb coated piezoelectric (PZ) quartz crystal immunosensors with homemade computer interfaces for signal acquisition and data processing were developed and applied for detection of human IgG and hemoglobin, respectively. The C60-antibody coated PZ Bio-Sensors for IgG and hemoglobin exhibited linear frequency responses to the concentrations of human IgG and hemoglobin with sensitivities of 1.25×10 2 Hz per decade (ΔHz/Δlog (mg/ml)) and 1.56×10 4 Hz/(mg/ml), respectively. Both C60-antibody coated PZ immunosensors showed detection limit of <10 −4 mg/ml for IgG and hemoglobin in aqueous solutions. Effects of pH and temperature on the frequency response of the IgG PZ immunosensor were also investigated. Optimum pH of the IgG solutions and optimum temperature for the IgG sensor were observed at pH=6.7 and 30 °C, respectively. The interference of various common species in the human blood, e.g., urea, uric acid, cysteine, tyrosine, ascorbic acid and metal ions, to the IgG PZ biosensor was also investigated. These species showed nearly no interference with the IgG PZ biosensor. The reproducibility and lifetime of these immobilized C60-antibody coated PZ immunosensors were also investigated and discussed.