Polyacrylic acid/polyethylene glycol hybrid antifouling interface for photoelectrochemical immunosensing of MDA-MB-231 cells using BiOBr/FeTPPCl/BiOI co-sensitized composite as matrix

An ultrasensitive photoelectrochemical (PEC) antifouling immunosensor was proposed using BiOBr/FeTPPCl/BiOI as matrix and polyacrylic acid (PAA)/polyethylene glycol (PEG) as hybrid antifouling interface for MDA-MB-231 detection. An indium tin oxide (ITO) electrode was successively modified with bismuth oxybromide (BiOBr) with layered crystal structure, which was sensitized with tetraphenyl iron(Ⅲ) porphyrin chloride (FeTPPCl) to widen the absorption range of visible light, and decorated with bismuth oxyiodide (BiOI) nanosheets to improve the PEC response. The joint action of PAA and PEG could offset the adsorption of non-specific proteins on the immunosensing interface for obtaining good antifouling performance. Based on the specific interaction of sialic acid (SA) on the cytomembrane with 3-aminophenylboronic acid (APBA), and the synergistic antifouling effect of PEG and PAA, a simple PEC immunosensing method was developed for the quantitative determination of MDA-MB-231 cells. This proposed antifouling PEC immunosensor exhibited a wide linear range (1 × 10 2 ∼ 1 × 10 6 cells·mL -1 ) and a low detection limit (30 cells·mL -1 ). The development of antibody-free immunosensors may improve the application for the diagnosis of human breast cancer.