In this study, we demonstrate the fabrication of graphene oxide sheet (GOS)-based surface plasmon resonance (SPR) sensors for protein immobilization detection. GOS was used as the medium owing to its high covalent binding affinity for proteins. We were able to monitor the binding phenomenon in real time using the SPR-based technique. Thus, this GOS sensor can detect bovine albumin serum (BSA) directly in GOS films and exhibited up to a 4.3-fold higher angle shift than that of the conventional Au/Cr-based sensor in 10 ng/ml of BSA. The results showed that the SPR biosensor formed using a GOS solution of 2 mg/ml has optimal sensitive and had a BSA detection limit as low as 100 pg/ml. The sensitivity of the slope ratio of the GOS vs. conventional Au substrate is 2.4:1. Moreover, GOS is a label-free detection without additional amplification steps to enhance the sensitivity. In addition, the average value of the affinity binding constant KA for the GOS-based sensor with respect to BSA was 80.8 × 106 M-1. These results suggest that GOS-based SPR biosensors have potential for use in high-sensitivity protein immobilization detection.
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