Graphene Nanoplatelets/Chitosan-Modified Electrochemical Immunosensor for the Label-Free Detection of Haptoglobin

Elevated levels of haptoglobin, a blood serum protein, have been implicated in a variety of disorders, such as cancer, diabetes mellitus, Crohn's disease and Parkinson's disease, to name a few. Due to its link to many disorders, it is therefore essential to develop a simple but sensitive technique for the detection of haptoglobin for the purpose of disease monitoring. To this end, we have developed a label-free electrochemical immunosensor that is superior to the conventional methods currently available for haptoglobin detection. The immunosensor involves simple physisorption of graphene nanoplatelets with the polysaccharide chitosan to develop a GNPs/Chi nanocomposite for subsequent detection of electrochemical signal, and together their collective properties synergistically resulted in a highly sensitive detection method. The immunosensor was able to detect a wide linear range of concentrations from 1 ng mL(-1) to 30 fg mL(-1) with a low limit of detection of 30 fg mL(-1). This developed immunosensor has proven to be extremely selective with great reproducibility and stability, with resistance to interference for the detection of haptoglobin. It is additionally sensitive enough to detect haptoglobin in human serum samples.