Enhanced Intracellular Delivery via a Titanium-Coated TiO₂ Microstructure Device: Leveraging an Infrared Laser for...

This study presents a novel optoporation technique using a titanium-coated TiO₂ microstructure (TMS) device activated by an infrared diode laser for highly efficient intracellular delivery. The TMS device, fabricated with 120 nm titanium coating on a titanium dioxide (TiO₂) microstructure containing microneedles (height ∼2 μm and width ∼4.5 μm), demonstrates enhanced biocompatibility and thermal conductivity compared to the conventional TiO₂ microstructure (MS). Exposure to the TMS device with an IR diode laser (980 nm) generates heat, forming photothermal bubbles that disrupt the cell membrane and create transient pores for biomolecular delivery. Unlike traditional optoporation methods, which rely on large, vibration-sensitive lasers, the IR diode laser-assisted TMS device-based optoporation technique offers a compact, cost-effective, and portable alternative, making it suitable for clinical and research applications in resource-constrained environments. The performance of the TMS and MS devices was compared in various cancer cell lines (HeLa, L929, and N2a), with the TMS device showing superior delivery success rates for biomolecules of varying molecular sizes. Notably, the TMS device achieved a 99.30% delivery success rate for the smallest molecule, PI dye, and an 85.17% success rate for the largest studied molecule, β-galactosidase enzyme-Cy5. Furthermore, the TMS device consistently provided a higher delivery success rate at lower laser power, minimizing cellular stress and preserving cell survivability. Moreover, using Western Blot analysis, the TMS device demonstrated lower levels of apoptosis compared to the MS device, with statistically significant differences, highlighting its potential for efficient intracellular delivery while minimizing cellular stress and damage. These results highlight the potential of the TMS device as an advanced tool for large-size intracellular biomolecular delivery, offering significant improvements in stability, efficiency, and cell survivability.