Micro/nano Nozzles for Gene Delivery
Particle Transport in Micronozzles
Micro/nano nozzles and diffusers have been used for ionic transport, drug and gene delivery. A mathematical model is developed to simulate the electroosmotic flow (EOF) and particle transport in micro/nano nozzles/diffusers. Particle motion is found to be dependent primarily on the particle charge and the wall charge. The calculated particle velocities compare well with experimental data.
Experiments have been done by Prof. J. L. Lee’s group to investigate particle transport in micronozzles. The Polymethyl Methacrylate (PMMA) nozzle is fabricated by photolithography, followed by replica molding and wet etching respectively. Negatively charged and fluorescence-labeled polystyrene (PS) beads of size from 3 nm to 40 nm were used to examine the transport of particles in micro-nozzles.
Modeling results for electroosmotic flow in the experimental microdiffuser. The height of the diffuser is 20 μm at the inlet and 130 μm at the outlet and the length of the diffuser is 650 μm. In this case, the EDLs are thin compared to the diffuser. The imposed electric field is 8,000 V/m and the ζ -potential is −15 mV.
Comparison of the analytical results and the experimental data. The length of the micro-diffuser is 650μm; the inlet height is 20μm and the outlet height is 130μm. The electric field is 80 V/cm. The ζ-potential of the PMMA walls are −15mV (Kirby and Hasselbrink, 2004). Both the particles and the walls are negatively charged.
Membrane Sandwich Electroporation
Nanotips can be used for drug/gene delivery. The aperture of nanotips can carry a specific dosage of drugs/genes and leave them inside cells. The short penetration of these tiny nanotips would not cause permanent damage to cells.
Single Cell in a DC Field
Experiments on gene delivery(left): A sigle cell is fixed in a micronozzle and the dots shows the pathlines of polystyrene beads. Modeling result for the applied electric field(right).
Design of the device for gene delivery using micro/nano nozzle arrays.