Metallic micro-ring device for highly efficient large cargo delivery in mammalian cells using infrared light pulses.

Uniform transfection of biomolecules into live cells with high delivery efficiency and cell viability is an immensely important area of biological research and has many biomedical applications. In the present study, we report highly efficient, uniform parallel intracellular delivery of small to very large biomolecules into diverse cell types using a titanium micro-ring (TMR) device activated by infrared (IR) light pulse. A TMR array device (2 cm × 2 cm) consists of a 10 µm outer diameter and 3 µm inner diameter for each micro-ring, and 10 µm interspacing between two micro-rings. Upon IR (1050 nm) pulse laser irradiation on the TMR device, photothermal cavitation bubbles are generated, disrupting the cell plasma membrane, and biomolecules are gently delivered into the cells by a simple diffusion process. This TMR device successfully delivered diverse types of small to very large biomolecules such as propidium iodide (PI; 668.4 Da) dye, dextran (3 kDa), small interfering RNA (13.3 kDa), enhanced green fluorescent protein expression plasmid DNA (6.2 kb), and ß-galactosidase enzyme (465 kDa) into human cervical (SiHa), mouse fibroblast (L929), and mouse neural crest-derived (N2a) cancer cells. For smaller molecules (PI dye), delivery efficiency and cell viability were achieved at ∼96% and ∼97%, respectively, with a laser fluence of 21 mJ cm-2 for 250 pulses. In contrast, ∼85% transfection efficiency and ∼90% cell viability were achieved for plasmid DNA with 45 mJ cm-2 laser fluence for 250 pulses in SiHa cells. Moreover, the intracellular delivery of ß-galactosidase enzyme was confirmed with confocal microscopy and flow cytometry analysis resulting in ∼83% co-staining of ß-galactosidase enzyme and calcein AM. Based on these efficient deliveries of diverse types of biomolecules in different cell types, the device has the potential for cellular diagnostic and therapeutic applications.