Homo/heterojunctions engineering on hollow multi-shelled TiO2 with remarkable photocurrent for cytosensing and in-situ evaluation of EGFR

Precise control over nanostructured scaffolds, such as hollow multi-shelled structures engineered to incorporate both homo- and heterojunctions, has been far less frequently mimicked. This study developed a sacrificial template method to synthesize hollow TiO₂ microspheres with a controlled number of shells and a closed, thin exterior shell. The rutile/anatase phases within the TiO₂ scaffold were regulated to form an optimized homojunction, followed by the in-situ growth of In₂S₃ nanoplates to construct a heterojunction. Detailed investigations illustrated that the coupling of homo- and heterojunctions established a type-Ⅱ configuration with well-aligned band-edge levels. Furthermore, the increased charge carrier density, rapid charge migration kinetics, and large electrochemically active surface area collectively contributed to outstanding photoelectrochemical (PEC) performance. As a result, the final composite served as an effective matrix to fabricate a PEC sensing platform for cell assays, with a limit of detection of 117 mL⁻¹ (S/N = 3). A novel strategy was proposed for evaluating epidermal growth factor receptor (EGFR) on the surface of different cell lines, further achieving actual applications in drug screening and physiological monitoring. This study not only explores PEC substrates by precisely engineering hollow architecture and energy band configurations, but also develops promising strategies for cytosensing and protein subtype assessment.