Chitosan–graphene oxide based aptasensor for the impedimetric detection of lysozyme

•The chitosan/graphene oxide (CHIT–GO) modified graphite electrode was developed as aptasensor.•DNA aptamer (APT) was covalently immobilized onto the surface of CHIT–GO modified electrode.•Surface characterization of these sensors were performed by SEM and EIS techniques.•The impedimetric lysozyme detection was performed by APT/CHIT–GO-PGE.•Our impedimetric aptasensor presented a good selectivity contrast to BSA and thrombin.

An impedimetric detection of lysozyme (LYS) was performed for the first time in this study at the surface of chitosan–graphene oxide (CHIT–GO) modified sensor based on the specific interaction process between DNA aptamer and its cognate protein, LYS.The amino linked DNA aptamer (APT) was covalently immobilized without using any chemical agents onto the surface of pencil graphite electrode (PGE). These PGEs are inexpensive and simple to use, and thus, they can be furtherly developed for a single-use application in a portable protein chip device. The electrochemical impedance spectroscopy (EIS) technique was used herein to analyze (i) the surface characterization of unmodified PGE and CHIT–GO modified PGE, and also (ii) the interaction between APT and LYS. The limit of detection (DL) was found as 0.38 μg/mL (equals to 28.53 nM). This impedimetric LYS aptasensor exhibited a higher selectivity toward thrombin and bovine serum albumin, even in the mixture samples.

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