Microfluidic Directed Self-Assembly of Liposome−Hydrogel Hybrid Nanoparticles

Abstract

We present a microfluidic method to direct the self-assembly of temperature-sensitive liposome-hydrogel hybrid nanoparticles. Our approach yields nanoparticles with structural properties and highly monodisperse size distributions precisely controlled across a broad range relevant to the targeted delivery and controlled release of encapsulated therapeutic agents. We used microfluidic hydrodynamic focusing to control the convective-diffusive mixing of two miscible nanoparticle precursor solutions (a DPPC:cholesterol:DCP phospholipid formulation in isopropanol and a photopolymerizable N-isopropylacrylamide mixture in aqueous buffer) to form nanoscale lipid vesicles with encapsulated hydrogel precursors. These precursor nanoparticles were collected off-chip and were irradiated with ultraviolet (UV) light in bulk to polymerize the nanoparticle interiors into hydrogel cores. Multiangle laser light scattering in conjunction with asymmetric flow field-flow fractionation was used to characterize nanoparticle size distributions, which spanned the approximately 150 to approximately 300 nm diameter range as controlled by microfluidic mixing conditions, with a polydispersity of approximately 3% to approximately 5% (relative standard deviation). Transmission electron microscopy was then used to confirm the spherical shape and core-shell composition of the hybrid nanoparticles. This method may be extended to the directed self-assembly of other similar cross-linked hybrid nanoparticle systems with engineered size/structure-function relationships for practical use in healthcare and life science applications.

Microfluidic hydrodynamic focusing based synthesis of POPC liposomes for model biological systems

“…Earlier studies have demonstrated the ability of vesicles synthesized by the microfluidics approach to encapsulate hydrophilic molecules including DNA fragments [25,29,54]. It has also been shown previously [25,30,43] and in this study that hydrophobic dye molecules can be incorporated in the vesicle lipid bilayer. All of these results show capability of the MHF approach to synthesize unilamellar lipid vesicles loaded with a versatile set of hydrophilic and hydrophobic molecules that can be used in simplified models of cellular compartments.…”

“…More recently, a new approach based on hydrodynamic focusing in micro-channels [24] has been developed and successfully applied in synthesis of vesicles of various lipids, as well as other types on nanoparticles [25][26][27][28][29][30]. Microfluidic hydrodynamic focusing (MHF) is conducted by introducing the lipid solution through a central inlet channel of a microfluidic device, and focusing this central stream by the flow of an aqueous solution through two or more side channels [24].…”

Analysis of a laminar-flow diffusional mixer for directed self-assembly of liposomes

“…Specifically, three previous studies generate liposomes of 100-nm or smaller at sheath-to-core ratios of 10 or greater, 14,43,44 whereas the present study generates liposomes in the range of 100-200 nm. This difference may occur as a consequence of adding DSPE-PEG, a hydrophilic and large molecular weight molecule, into the lipid solution.…”

Self-Assembly in Micro- and Nanofluidic Devices: A Review of Recent Efforts

“…Indeed, because of the emergence of new materials, especially those with potential for use in microelectronic, photonic, and biomedical applications, interest in the applications of self-assembly to components larger than molecules have grown dramatically. At a larger scale, self-assembly has been employed to produce microcontainers [11], janus/ternary microparticles of varied packing and surface characteristics [12], large scale crystalline nanoarrays [13], and liposomes [14].…”

“…Micro-and nanofluidic technology is arguably the most promising candidate to overcome the bottleneck of bulk techniques as it enables a range of fundamental features to accompany system miniaturization such as high spatial and temporal resolution, high throughput, ease of chemical and biological micro-and nanopatterning, reduced reagent consumption, high resolution and sensitivity, low cost, well-controlled supply of reagents due to laminar flow, dominant surface tension effect, and potential for sensor and actuator integration. There are several outstanding examples of successful applications of self-assembly in micro-and nanofluidic devices: from material synthesis of plasmonic nanomaterials [17], molecular separation of DNA based on self-patterning of crystalline nanoarray [13], to preparation of temperature sensitive liposome-hydrogel hybrid nanoparticles for targeted delivery [14].…”