Label-free electrochemical immunosensor based on L-cysteine-functionalized AuNP on reduced graphene oxide for the detection of dengue virus E-protein in dengue blood serum

Dengue fever is one of the most deadly viruses, and it has become a recurring public health problem in tropical areas. The increase in dengue cases worldwide has increased the demand for rapid and accurate diagnostic methods. In order to detect the content of dengue virus type E-proteins (DENV-E protein), we fabricated an efficient label-free electrochemical immunosensor platform that was constructed based on in situ reduction and functionalized gold nanoparticles decorated heteroatom-doped reduced graphene oxides nanocomposites (AuNPs/NSG). Here, L-cystein (L-cys) is introduced to green reducing and stabilizing agent of Au(III) and graphene oxide. The sensing platform offers a suitable higher number of antibody immobilization by providing Lcys. The highly crystalline AuNP was unfoirmly grafting on 2D graphene sheet. Under the optimized conditions, the as-designed immunosensor exhibited a wide linear working range from 0.01-100 ng mL-1 with a low detection limit of 1.6 pg mL-1 for DENV-E detection. The proposed immunosensor shows high selective for discriminating DENV-E against antibodies of their antibodies, including the closely related DENV. The reliability of fabricated immunosensor had been used to detect the viral E-protein contents in serum samples collected from patients, and obtained results were compared with the enzyme-linked immunosorbend assay. Furthermore, the developed AuNPs/NSG immunosensor can be used as a potential probe for future prospective clinical diagnostic applications.

Automated summary

A label-free electrochemical immunosensor platform was fabricated using AuNPs/NSG for detecting DENV-E protein content, showing a wide linear working range and low detection limit with high selectivity for discriminating DENV-E against other antibodies. The platform has the potential for future clinical diagnostic applications.