Tailoring ZnO nanowire morphology by substrate-position-controlled VLS growth for label-free protein sensing

ZnO nanostructures are emerging as powerful platforms for optical biosensing; however, direct control over the relationship between morphology and sensing performance remains challenging. In this study, ZnO architectures were engineered via vapor–liquid–solid (VLS) growth using substrate-position control, leading to the formation of nanowires with branched tree-like morphologies and different optical signatures. Intense defect-related photoluminescence (PL) was systematically quenched upon adsorption of thiolated bovine serum albumin (BSA-thiol). After UV activation, submicromolar detection (0.6 μM) was achieved, placing this platform among the most sensitive label-free optical biosensors reported to date. A direct correlation between growth parameters, morphology, and biosensing efficiency was established, providing a strategy for tailoring ZnO surfaces for protein detection. • VLS growth tuning substrate position yields novel tree-like ZnO nanowires. • First direct link between ZnO morphology and protein sensing performance. • Defect-related PL quenching enables label-free detection down to 0.6 μM. • UV activation enhances ZnO–protein interactions for sensitive biosensing. • Morphology-guided design paves route to next-gen optical biosensors.