Integrated optical tweezers and two-photon excitation for spatiotemporal control of DNA cargo release

Optical tweezers have been widely used as a versatile tool in various biomedical applications due to their ability to precisely manipulate micrometer-sized particles. However, integrating controlled cargo release with optical trapping remains challenging, particularly because most photo-responsive particle systems for controlled cargo release rely on ultraviolet (UV) light, which can induce photodamage and exhibits limited tissue penetration. To address these challenges, we developed a hybrid optical platform that integrates optical tweezers with two-photon excitation using a 780 nm femtosecond pulsed laser for spatiotemporally controlled cargo release. Using fluorescent particles with UV absorption, we demonstrated that fluorescence excitation was restricted to the optically trapped particle, confirming highly localized excitation within the laser focal volume. To evaluate light-controlled cargo release, we prepared DNA-loaded particles using photocleavable (PC) DNA linkers and investigated their release under two-photon excitation. Our results demonstrate that localized two-photon excitation can effectively trigger cargo release through selective photocleavage with spatially confined excitation. The proposed hybrid optical platform enables simultaneous particle manipulation and spatiotemporally controlled cargo release, providing a versatile approach for light-controlled biomedical applications with potential for future integration into gene delivery strategies.