(252g) Hybrid-Field Microfluidics Enhanced Polyplex Synthesis and Delivery

Micro/nanofluidics has great potentials for many biomedical applications, such as noviral gene delivery with polyplex and lipoplex. Hydrodynamic focusing microfluidics and other flow patterns have been successfully used for improving the synthesis quality of such nanoparticle probes. In these applications, it is cirtical to ensure efficient initial interactions between molecular probes and their later conjugation homogeneity. Therefore, it is highly desired to bring cationic polymers, DNA, or both to their conjugation interfaces for efficient packing and production of nanocarriers only overthere. Here we introduce a hybrid field microfluidic (HFM) approach to create such conjugation environment (interfacial conjugation) for efficient polyplex synthesis and delivery. In HFM, an electric field is imposed at desired locations and appropriate moments to balance the flow stress on negatively charged DNA molecules to effectively regulate their initial conformations, deformation dynamics, and accumulation in flows. Under appropriate conditions, DNA molecules could continuosly accumulate at the interface of different flow streams from the main flow in a hydrodynamic focusing setup, where the conjugation with polyethylenimine (PEI) occurs. Frequently switching the electric field helps retain most probes at the conjugation interface while avoid potential drawbacks such as large aggregates and Joule heating. Atomic force microscopy (AFM) and dynamic light scattering (DLS) results confirmed the good complexation quality of polyplex nnaoparticles. The delivery efficiency was evaluated with mammalian cells with better cellular uptake of molecular probes and reduced adverse effects. This new nanoparticle synthesis concept may stimulate further exploration in the delivery of various therapeutic materials for both in vitro and in vivo applications.