Phospholipid-Block Copolymer Hybrid Vesicles with Lysosomal Escape Ability.

The success of nanoparticulate formulations in drug delivery depends on various aspects including their toxicity, internalization, and intracellular location. Vesicular assemblies consisting of phospholipids and amphiphilic block copolymers are an emerging platform, which combines the benefits from liposomes and polymersomes while overcoming their challenges. We report the synthesis of poly(cholesteryl methacrylate)- block-poly(2-(dimethylamino) ethyl methacrylate) (pCMA- b-pDMAEMA) block copolymers and their assembly with phospholipids into hybrid vesicles. Their geometry, their ζ-potential, and their ability to adsorb onto polymer-coated surfaces were assessed. Giant unilamellar vesicles were employed to confirm the presence of both the phospholipids and the block copolymer in the same membrane. Furthermore, the cytotoxicity of selected hybrid vesicles was determined in RAW 264.7 mouse macrophages, primary rat Kupffer cells, and human macrophages. The internalization and lysosomal escape ability of the hybrid vesicles were confirmed using RAW 264.7 mouse macrophages. Taken together, our findings illustrate that the reported hybrid vesicles are a promising complementary drug delivery platform for existing liposomes and polymersomes.

Mucopenetrating micelles with a PEG corona.

Crossing the intestinal mucus layer is a long-standing challenge for orally delivered nanoparticles carrying therapeutic cargo. We report the assembly of mucopenetrating cargo-loaded micelles using block copolymers consisting of either linear poly(ethylene glycol) (PEG) or bottle-brush poly(oligo(ethylene glycol)methacrylate) (PEGb) as the hydrophilic block and poly(caprolactone) (PCL) or poly(cholesteryl methacrylate) (PCMA) as the hydrophobic extension. The micelles were shown to preserve their stability and retain ∼50% of their cargo in simulated gastric fluid. The ability of micelles to diffuse through reconstituted porcine mucus was assessed in a microfluidic set-up. Finally, the delivery of Nile Red as a hydrophobic model cargo across a mucus layer produced by epithelial cells was demonstrated. These engineered mucopenetrating micelles have potential to be developed into efficient absorption enhancers, contributing a nanotechnology solution to oral drug delivery.

Enzymes as key features in therapeutic cell mimicry.

Cell mimicry is a nature inspired concept that aims to substitute for missing or lost (sub)cellular function. This review focuses on the latest advancements in the use of enzymes in cell mimicry for encapsulated catalysis and artificial motility in synthetic bottom-up assemblies with emphasis on the biological response in cell culture or more rarely in animal models. Entities across the length scale from nano-sized enzyme mimics, sub-micron sized artificial organelles and self-propelled particles (swimmers) to micron-sized artificial cells are discussed. Although the field remains in its infancy, the primary aim of this review is to illustrate the advent of nature-mimicking artificial molecules and assemblies on their way to become a complementary alternative to their role models for diverse biomedical purposes.

Double-Fueled Janus Swimmers with Magnetotactic Behavior.

Self-propelled particles attract a great deal of attention due to the auspicious range of applications for which nanobots can be used. In a biomedical context, self-propelled swimmers hold promise to autonomously navigate to a desired location in an attempt to counteract cell/tissue defects either by releasing drugs or by performing surgical tasks. The vast majority of prior reports deal with single engine assemblies, often utilizing fuel molecules which are considered to be highly cytotoxic. Herein, we introduce two engines: (1) a motor which couples enzymes (i.e., glucose oxidase) and inorganic nanoparticles (i.e., platinum nanoparticles) to gain power and (2) a peptide-fueled trypsin motor. We demonstrate that both engines can induce enhanced diffusion properties of (Janus) particles using bioavailable and completely harmless fuel molecules. By combining both engines on the same carrier, we show self-propelled particles employing two independent engines, using two different fuels. A collaborative enhancement of the swimmer's diffusion properties upon powering-up both engines simultaneously is observed. Additionally, the incorporation of magnetic nanoparticles allows for the swimmer to move in a magnetic gradient upon applying an external magnetic field, yielding in directional motion of the double-fueled particles. These multiple-fueled biocompatible swimmers are a significant contribution to make them applicable in a biomedical context.

Planar and Cell Aggregate-Like Assemblies Consisting of Microreactors and HepG2 Cells.

The assembly of microreactors has made considerable progress toward the fabrication of artificial cells. However, their characterization remains largely limited to buffer solution-based assays in the absence of their natural role model-the biological cells. Herein, the combination of microreactors with HepG2 cells either in planar cell cultures or in the form of cell aggregates is reported. Alginate (Alg)-based microreactors loaded with catalase are assembled by droplet microfluidics, and their activity is confirmed. The acceptance of polymer-coated ∼40 µm Alg particles by proliferating HepG2 cells is depending on the terminating polymer layer. When these functional microreactors are cocultured with HepG2 cells, they can be employed for detoxification, that is, hydrogen peroxide removal, and by doing so, they assist the cells to survive. This report is among the first successful combination of microreactors with biological cells, that is, HepG2 cells, contributing to the fundamental understanding of integrating synthetic and biological partners toward the maturation of this semisynthetic concept for biomedical applications.