Search for: All records

We demonstrate optically pumped blue lasing at room temperature in a merged moiré photonic crystal fabricated out of gallium nitride with embedded, fragmented quantum wells. Lasing occurs at two closely spaced wavelengths of 450 and 451 nm, matched to simulated flat bands induced by the moirésuperlattice. Both thresholds occur at 30 μJ/cm2. Light in−light out curves were taken at both room temperature and 77 K across different gain materials, including fragmented quantum wells, continuous quantum wells, and quantum dots. Lasing was observed only at room temperature in fragmented quantum well devices, suggesting the importance of gain material carrier dynamics in unconventional laser cavities like the moiré design explored. These insights and the experimental validation of moiré simulations in a previously unexplored III−V material indicate promise toward a new kind of efficient, tunable laser. 

Intracellular delivery is crucial for cellular engineering and the development of therapeutics. Laser-activated thermoplasmonic nanostructured surfaces are a promising platform for high-efficiency, high-viability, high-throughput intracellular delivery. Their fabrication, however, typically involves complicated nanofabrication techniques, limiting the approach’s applicability. Here, colloidal self-assembly and templating are used to fabricate large arrays of thermoplasmonic nanocavities simply and cost-effectively. These laser-activated substrates are used to deliver membrane-impermeable dye into cells at an efficiency of 78% and throughput of 30 000 cells min–1 while maintaining 87% cell viability. Proof-of-concept data show delivery of large cargoes ranging from 0.6 to 2000 kDa to cells without compromising viability. 

Abstract The delivery of biomolecules into cells relies on porating the plasma membrane to allow exterior molecules to enter the cell via diffusion. Various established delivery methods, including electroporation and viral techniques, come with drawbacks such as low viability or immunotoxicity, respectively. An optics-based delivery method that uses laser pulses to excite plasmonic titanium nitride (TiN) micropyramids presents an opportunity to overcome these shortcomings. This laser excitation generates localized nano-scale heating effects and bubbles, which produce transient pores in the cell membrane for payload entry. TiN is a promising plasmonic material due to its high hardness and thermal stability. In this study, two designs of TiN micropyramid arrays are constructed and tested. These designs include inverted and upright pyramid structures, each coated with a 50-nm layer of TiN. Simulation software shows that the inverted and upright designs reach temperatures of 875 °C and 307 °C, respectively, upon laser irradiation. Collectively, experimental results show that these reusable designs achieve maximum cell poration efficiency greater than 80% and viability greater than 90% when delivering calcein dye to target cells. Overall, we demonstrate that TiN microstructures are strong candidates for future use in biomedical devices for intracellular delivery and regenerative medicine.