All-in-one smartphone imaging for visual immunobiosensing of cancer biomarker using electronic gyro-centrifuge and nanozyme

Integrated functionality that combines recognition elements and sensors on a single platform to provide real-time detection capabilities for fifth-generation biosensors is considered one of the dominant tools for addressing point-of-care testing in the community today. Inspired by gyroscope and smartphone-based sensors, we developed a portable and low-cost immunobiosensor for high-throughput detection of cancer-related markers. The main testing process was divided into two parts: blood sample preprocessing based on an electronic gyroscope and signal reading based on nanozyme and smartphone. The feasibility of a commercial electronic gyroscope for serum acquisition from whole blood samples was evaluated. In addition, PtCd nanoclusters (PtCd NCs) were used as excellent peroxidase-like nanozymes to trigger the target signal conversion of the immunosensor. PtCd NCs were able to catalyze the conversion of H2O2 to ·OH, which rapidly oxidized the colorless 3,3',5,5'-tetramethylbenzidine (TMB) substrate to the blue Oxidized-TMB (oxTMB). Naked eye visible obvious color change and the RGB values of the color metrology system could also be read by smartphone. Prostate-specific antigen (PSA) as a model biomarker was used to validate the utility of an integrated immunoassay system to enable early cancer screening through localization of RGB values. This work focuses on convenient blood sample preprocessing and simplified serologic cancer screening steps to develop an efficient and cost-effective immunoassay platform for community and on-site point-of-care testing (POCT) in resource-limited settings.