Green synthesis of copper iodide nanoparticles: gamma irradiation for spectroscopic sensing of cancer biomarker CA 19-9

A simple, fast, green and cost-effective method is designed for the synthesis of copper iodide nanoparticles (CuI-NP) for spectroscopic detection of cancer biomarker, carbohydrate antigen 19-9 (CA 19-9). Results of UV-visible spectroscopy establish the efficacy of prepared CuI-NP to sense CA 19-9 in serum medium even at its low concentration (~ 0.066 U/mL). Our study reveals that γ-irradiated (24 h) copper iodide nanoparticles (CuI-NP-γ) have higher sensitivity towards CA 19-9 sensing due to their higher surface activity and charged nature as compared to CuI-NP. CuI-NP-γ could deliver higher signal enhancement and was able to lower the limit of detection (LOD) of CA 19-9 from 0.082 to 0.066 U/mL. Results also indicate that in presence of high concentration of glucose, cholesterol, bilirubin and insulin, which cause pathophysiological disorders like diabetes, hypercholesterolemia, hepatic disorder, hyperinsulinemia, etc., the LOD is even lower (0.037, 0.034, 0.157, 0.029 U/mL respectively). The interaction between the biomarker and the NPs were further established using fluorescence and circular dichroism spectroscopy. The specificity of sensing was tested by checking the response in presence of other biomarkers, like CEA and CA-125 which did not show any signal enhancement with CuI-NP-γ.