Fabrication of an imprinted polymer based graphene oxide composite for label-free electrochemical sensing of Sus DNA

Abstract

An innovative label-free electrochemical sensor was developed for selective detection of Sus (pig) deoxyribonucleic acid (DNA) through adenine imprinted polypyrrole fabricated on the surface of allyl mercaptan modified GO (MIP/mGO). Different techniques were used to characterize the molecularly imprinted polymer on modified graphene oxide (MIP/mGO) composite including Fourier transform infrared (FTIR) spectroscopy, Energy dispersive spectroscopy (EDS), Surface enhanced microscopy (SEM), Atomic force microscopy (AFM) and Raman spectroscopy. The results obtained from FTIR spectroscopy and EDS confirmed the successful fabrication of all the materials. Raman results further confirmed the fabrication of single layered GO and polymeric composites. The mGO, MIP/mGO and NIP/mGO based electrochemical sensors were also characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The EIS results revealed that mGO was the most conductive among all the sensors with a minimum charge transfer resistance (R_ct) of 200 Ω. However, the R_ct values of MIP/mGO and NIP/mGO were found as 832 Ω and 5447 Ω, respectively. The electrochemical sensor based on MIP/mGO was utilized to establish an electrochemical method for the detection of Sus DNA. Differential pulse voltammetry (DPV) was used to quantify the amount of Sus DNA. The essential parameters such as the type of electrolyte, pH of electrolyte, scan rate and potential range were thoroughly optimized. Sus DNA produced a good DPV response using Britton–Robinson (BR) buffer of pH 2 at a scan rate of 50 mV/s in the potential range of −0.2 V to 0.6 V. The developed method was comprehensively validated and found to be linear in the range of 0.39 to 20 ng mL⁻¹ of Sus DNA, with a limit of detection of 0.13 ng mL⁻¹ and a limit of quantification of 0.39 ng mL⁻¹, respectively. The fabricated MIP/mGO based electrochemical sensor was found to be 2.0 times more selective for Sus DNA than for Gallus domesticus (chicken) DNA and did not show any response to Bos taurus (cow) DNA in the voltage range of Sus DNA response. The applicability of the developed sensor was also checked for food samples and good percent recovery was obtained.