Microfluidic delivery of small molecules into mammalian cells based on hydrodynamic focusing.
Microfluidics-based cell assays offer high levels of automation and integration, and allow multiple assays to be run in parallel, based on reduced sample volumes. These characteristics make them attractive for studies associated with drug discovery. Controlled delivery of drug molecules or other exogenous materials into cells is a critical issue that needs to be addressed before microfluidics can serve as a viable platform for drug screening and studies. In this study, we report the application of hydrodynamic focusing for controlled delivery of small molecules into cells immobilized on the substrate of a microfluidic device. We delivered calcein AM which was permeant to the cell membrane into cells, and monitored its enzymatic conversion into fluorescent calcein during and after the delivery. Different ratios of the sample flow to the side flow were tested to determine how the conditions of hydrodynamic focusing affected the delivery. A 3D numerical model was developed to help understand the fluid flow, molecular diffusion due to hydrodynamic focusing in the microfluidic channel. The results from the simulation indicated that the calcein AM concentration on the outer surface of a cell was determined by the conditions of hydrodynamic focusing. By comparing the results from the simulation with those from the experiment, we found that the calcein AM concentration on the cell outer surface correlated very well with the amount of the molecules delivered into the cell. This suggests that hydrodynamic focusing provides an effective way for potentially quantitative delivery of exogenous molecules into cells at the single cell or subcellular level. We expect that our technique will pave the way to high-throughput drug screening and delivery on a microfluidic platform.
Wang
Fen
F
Department of Agricultural and Biological Engineering, 225 S. University Street, Purdue University, West Lafayette, Indiana 47907, USA.
Wang
Hao
H
Wang
Jun
J
Wang
Hsiang-Yu
HY
Rummel
Peter L
PL
Garimella
Suresh V
SV
Lu
Chang
C
D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000737:chemistry*; D018914:Cells, Immobilized; D003198:Computer Simulation; D006224:Cricetinae; D003412:Cricetulus; D016503:Drug Delivery Systems / Q000379:methods*; D005452:Fluoresceins / Q000008:administration & dosage* / Q000737:chemistry*; D044085:Microfluidics / Q000295:instrumentation* / Q000379:methods; D008845:Microinjections / Q000295:instrumentation* / Q000379:methods; D008954:Models, Biological; D011312:Pressure
D005452:Fluoresceins; C085925:calcein AM