Specific Uptake of Lipid-Antibody-Functionalized LbL Microcarriers by Cells

Abstract

The modular construction of Layer-by-Layer biopolymer microcarriers facilitates a highly specific design of drug delivery systems. A supported lipid bilayer (SLB) contributes to biocompatibility and protection of sensitive active agents. The addition of a lipid anchor equipped with PEG (shielding from opsonins) and biotin (attachment of exchangeable outer functional molecules) enhances the microcarrier functionality even more. However, a homogeneously assembled supported lipid bilayer is a prerequisite for a specific binding of functional components. Our investigations show that a tightly packed SLB improves the efficiency of functional components attached to the microcarrier's surface, as illustrated with specific antibodies in cellular application. Only a low quantity of antibodies is needed to obtain improved cellular uptake rates independent from cell type as compared to an antibody-functionalized loosely packed lipid bilayer or directly assembled antibody onto the multilayer. A fast disassembly of the lipid bilayer within endolysosomes exposing the underlying drug delivering multilayer structure demonstrates the suitability of LbL-microcarriers as a multifunctional drug delivery system.

Reversible Fusion Proteins as a Tool to Enhance Uptake of Virus-Functionalized LbL Microcarriers

“…From previous investigations it has been shown that a significant interaction between SLB-LbL microcarriers and Vero cells does not occur prior to 3 h post coincubation. 44 However, cellular internalization of lipid-enveloped viruses via clathrin-mediated endocytosis occurs within a few minutes. 45 Therefore, the interaction of the VSV-LbL microcarriers was monitored by means of FC over relatively short time frames of 30 and 60 min (comparing red fluorescent cells and nonfluorescent cells).…”

“…LbL microcarriers were surface coated with an additional lipid bilayer. Therefore, liposomes were prepared as described according to Gose et al 15,44 POPS and POPC were mixed in a 1:1 molar ratio. The dried lipids were rehydrated with 522 μL of PBS (without calcium and magnesium) to obtain a 10.2 mM lipid solution.…”

Enhanced Uptake and Endosomal Release of LbL Microcarriers Functionalized with Reversible Fusion Proteins

“…As a platform for the VSV, the LbL microcarriers were additionally equipped with a supported lipid bilayer (SLB). Preparation of liposomes as a prerequisite for an SLB was performed as described in Gose et al 39 LbL microcarriers equipped with an SLB were named as SLB-LbL microcarriers.…”

“…To analyze the processing of the supported lipid bilayer of the LbL microcarrier after internalization, the SLB was equipped with 0.1 mol % of PE-RITC. 39 Again, cells were seeded in chamber slides with a density of 5 × 10 4 cells per well. Microcarriers were applied to cells at a 5:1 ratio, and cells were stained with Hoechst33342 after the respective time points.…”

Protein A Functionalized Polyelectrolyte Microcapsules as a Universal Platform for Enhanced Targeting of Cell Surface Receptors

“…After targeting is being achieved, the actual uptake mechanism allowing for encapsulated cargo to be delivered to the cell, as well as the uptake specificity must be investigated in detail. 38,58 It is known that particle size, shape, and mechanical properties could influence the interaction with cells and uptake substantially. 59,60 If the capsules are taken up by cells via the endocytic pathway, which is the major uptake mechanism of cells for larger entities, their endosomal escape can be facilitated by several viral and bacterial proteins, synthetic biomimetic peptides, polymers, etc.…”