γ -Irradiated CuS-graphene nanoparticles for selective optical sensing of cancer biomarker CA-125

Selective optical sensing of ovarian cancer biomarker carbohydrate antigen 125 (CA-125) in serum medium is established here using an easy, rapid and economic method. A naturally occurring plant polyphenol, epigallocatechin gallate is used for the generation of copper sulphide nanoparticles (10–12 nm). The nanoparticles were further incorporated in graphene nanoplatelets and irradiated with γ-radiations (CuS-Gr-γ-NP) (total dose 30 kGy) and used for the optical sensing of CA-125. UV–Visible spectroscopic results reveal that the CuS-Gr-γ-NP enhanced the CA-125 sensing ability with a notable limit of detection (LOD) value of 0.019 U/mL compared to pristine CuS-NP (LOD 0.090 U/mL). Furthermore, improvement of CA-125 sensing by CuS-Gr-γ-NP was observed in presence of interfering biomolecules like glucose, cholesterol and insulin in serum as the LOD values further lower down to the range of 0.007–0.019 U/mL. Fluorescence, circular dichroism and Raman spectroscopy are used to study the underlying mechanism of CA-125 sensing by CuS-Gr-γ-NP. Molecular docking studies of the interaction between CuS-Gr-γ-NP and CA-125 also support the experimental results. The novelty of the work lies on the fact that CA-125 could be sensed in serum medium using the spectral property of CuS-Gr-γ-NP. This is a one-of-a-kind study without involving CA-125 antibody. Furthermore, sensing assays were performed in presence of certain biomolecules in serum which mimic several pathophysiological conditions in body, like, diabetes, hypercholesterolemia, hyperinsulinemia, etc. Thus, this proposed easy and rapid method holds the potential for clinical applicability in an economic way.