Enhanced Intraliposomal Metallic Nanoparticle Payload Capacity Using Microfluidic-Assisted Self-Assembly

Abstract

Hybrids composed of liposomes (L) and metallic nanoparticles (NP) hold great potential for imaging and drug delivery purposes. However, the efficient incorporation of metallic nanoparticles into liposomes using conventional methodologies has so far proved to be challenging. In this study, we report the fabrication of hybrids of liposomes and hydrophobic gold nanoparticles of size 2-4 nm (Au) using a microfluidic assisted self-assembly process. The incorporation of increasing amounts of Au nanoparticles into liposomes was examined using microfluidics and compared to L-AuNP hybrids prepared by the reverse-phase evaporation method. Our microfluidics strategy produced L-AuNP hybrids with a homogeneous size distribution, smaller polydispersity index, and a 3-fold increase in loading efficiency when compared to those hybrids prepared using the reverse-phase method of production. Quantification of the loading efficiency was determined by ultraviolet spectroscopy, inductively coupled plasma mass spectroscopy and centrifugal field flow fractionation and confirmed qualitatively by transmission electron microscopy. The higher loading of gold nanoparticles into the liposomes achieved using microfluidics produced a slightly thicker and more rigid bilayer as determined with small angle neutron scattering. These observations were confirmed using fluorescent anisotropy and atomic force microscopy, respectively. Structural characterization of the liposomal-nanoparticle hybrids with cryo-electron microscopy revealed the coexistence of membrane-embedded and interdigitated nanoparticle-rich domains suggesting AuNP incorporation through hydrophobic interactions. The microfluidic technique that we describe in this study allows for the automated production of monodisperse liposomal-nanoparticle hybrids with high loading capacity highlighting the utility of microfluidics to improve the payload of metallic nanoparticles within liposomes, thereby enhancing their application for imaging and drug delivery.

Microfluidic Synthesis and Purification of Magnetoliposomes for Potential Applications in the Gastrointestinal Delivery of Difficult-to-Transport Drugs

“…Figure 3 shows the TEM characterization of the MLPs obtained with both the two-layer and three-layer devices. The images show that the MLPs formed correctly and in agreement with previous reports of MLPs synthesized via microfluidics [34,35]. The images also show that the size of the MLPs obtained for the three-layer device is slightly larger than that obtained with the two-layer device, which agrees well with the hydrodynamic diameters measured via DLS.…”

“…Currently, liposome preparation techniques using microfluidic systems have allowed greater control over physical properties, yielding massive and robust production of MLPs with uniform size distribution, high loading efficiencies, and reduced costs [33][34][35]. Nevertheless, there is still a challenge in the separation and sample purification methods due to the minor size differences between the MLPs and the non-encapsulated nanoparticles [32,36].…”

Fabrication and Applications of Microfluidic Devices: A Review

“…Much interest has also been drawn to the microfluidic platform synthesis of liposomes, as they represent highly efficient drug delivery systems [128]. Liposomal carriers achieve selective and sufficiently precise localization of the diseased site, also ensuring a slow and sustained release [134,135], the features required for the treatment of cancers and inflammatory conditions [136], infections, meningitis, malaria, HIV, hepatitis A, and influenza [137]. Liposomes of well-controlled sizes can encapsulate small molecules, such as amphotericin B and doxorubicin [138], being proposed to deliver vaccines, anticancer drugs, and gene therapy [134].…”

In Silico Analysis of Microfluidic Systems for the Purification of Magnetoliposomes

“…Despite the progress, these methods pose some challenges, including the relatively large particle size distribution, heterogeneous morphology, and, most importantly, the difficulty in separating the non-encapsulated/unbound MNPs [9]. Recent reports have demonstrated that these issues can be addressed through more precise control of assembly conditions at the microscale via microfluidic devices [10,11].…”

“…In this regard, microfluidic systems have enabled the massive production of MLs with more homogeneous physicochemical, uniform size distribution, high loading efficiencies and reduced costs [4,11,10]. Despite the significant advances in the synthesis and liposomal encapsulation technologies (LET) provided by microfluidics, proper separation methods are still a major challenge.…”