A synergistic effect of gold nanoparticles and melamine with signal amplification for C-reactive protein sensing

Novel synergistic effect between gold nanoparticles (AuNPs) and melamine (MEL) signal amplification were used to develop a sensor in this study to detect C-reactive protein (CRP). A ferrocene derivative (Fc-ECG) was used as electrochemical probe, as well as sensitive element, to prepare the sensor. The Fc-ECG/MEL/AuNPs/SPE disposable electrochemical sensor was fabricated by depositing AuNPs onto the SPE. Combination with MEL for their synergistic effect allowed for dual signal amplification, which was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. Under optimized conditions, the developed sensor presented a linear concentration range from 0.001 to 1000 μg mL −1 , and relationship between peak current response and logarithm of CRP concentration was represented by the following regression equation: I (μA) = 7.6468–0.78446 lgC (μg mL −1 ) with 0.99506 correlation coefficient (R 2 ). The detection limit for the sensor was 0.30 ng mL −1 and sensitivity was 11.10 μA μg −1 mL cm −2 . When compared to CS/Fc(COOH)/SPE sensor, the detection limit was lowered 1000 times, and sensitivity was improved 56 times by the prepared sensor. The sensor was also used in human serum samples, with 98.69–102.43% recovery and lower than 6.59% total R.S.D, indicating that it is also usable for rapid detection of CRP in actual samples.