Smartphone-Integrated Biopolymer-Based Immunosensing Platform for Osteosarcoma Biomarker Analysis

Abstract

Osteopontin (OPN) is an important biomarker related to osteosarcoma, potentially the most aggressive bone cancer, that plays a vital role in tumor initiation, progression, and metastasis. Here, we present a label-free, stable, and highly specific electrochemical immunosensor for sensitive detection of OPN. The sensing interface was engineered using a Manganese hexacyanoferrate- chitosan (MnHCF-CS) composite subsequently layered on an rGO modified electrode to form a biocompatible, self-reporting redox-active interface, followed by immobilization of anti-OPN antibodies via the bioconjugation chemistry. All electrochemical measurements, namely linear sweep voltammetry, and electrochemical impedance spectroscopy, were performed in PBS, the only solvent required to generate analytical signals. The immunosensor exhibited a stable, reproducible redox response, sufficient anti-interference properties, and high selectivity for the detection of OPN. The combined effects of gold nanoparticles, rGO, and the MnHCF-CS composite resulted in a greater electroactive surface area, improved conductivity, and enhanced antibody stabilization. To assess the concentration of OPN, a smartphone-integrated application, ‘‘OsteoPredictor,’’ was developed as an easy-to-use platform. This buffer-based immunosensor showed potential for early osteosarcoma diagnosis and ultimately, point-of-care (POC) analysis. The developed sensor system demonstrates excellent analytical performance, achieving a low detection limit of 0.156 ng/mL (RSD < 4.72%, n = 3) and a wide linear detection range of 10–1000 ng/mL. Its applicability was validated in human serum, confirming its application in a realistic environment.