Cell culture-based intestinal models are important to evaluate nanoformulations intended for oral drug delivery. We report the use of a floating structured paper chip as a scaffold for Caco-2 cells and HT29-MTX-E12 cells that are two established cell types used in intestinal cell models. The formation of cell monolayers for both mono- and cocultures in the paper chip are confirmed and the level of formed cell–cell junctions is evaluated. Further, cocultures show first mucus formation between 6–10 days with the mucus becoming more pronounced after 19 days. Hybrid vesicles (HVs) made from phospholipids and the amphiphilic block copolymer poly­(cholesteryl methacrylate)-block-poly­(2-carboxyethyl acrylate) in different ratios are used as a representative soft nanoparticle to assess their mucopenetration ability in paper chip-based cell cultures. The HV assembly is characterized, and it is illustrated that these HVs cross the mucus layer and are found intracellularly within 3 h when the cells are grown in the paper chips. Taken together, the moist three-dimensional cellulose environment of structured paper chips offers an interesting cell culture-based intestinal model that can be further integrated with fluidic systems or online read-out opportunities.

Artificial organelles are envisioned as nanosized assemblies with intracellular biocatalytic activity to provide the host cells with non-native or missing/lost function.

Catalyzing biochemical reactions with enzymes and communicating with neighboring cells via chemical signaling are two fundamental cellular features that play a critical role in maintaining the homeostasis of organisms. Herein, we present an artificial enzyme (AE) facilitated signal transfer between artificial cells (ACs) and mammalian HepG2 cells. We synthesize metalloporphyrins (MPs) based AEs that mimic cytochrome P450 enzymes (CYPs) to catalyze a dealkylation and a hydroxylation reaction, exemplified by the conversion of resorufin ethyl ether (REE) to resorufin and coumarin (COU) to 7‐hydroxycoumarin (7‐HC), respectively. The AEs are immobilized in hydrogels to produce ACs that generate the two diffusive fluorophores, which can diffuse into HepG2 cells and result in dual intracellular emissions. This work highlights the use of AEs to promote AC to mammalian signal transfer, which opens up new opportunities for integrating the synthetic and living world with a bottom‐up strategy.

Artificial biology is an emerging concept that aims to design and engineer the structure and function of natural cells, organelles, or biomolecules with a combination of biological and abiotic building blocks. Cell mimicry focuses on concepts that have the potential to be integrated with mammalian cells and tissue. In this feature article, we will emphasize the advancements in the past 3–4 years (2017‐present) that are dedicated to artificial enzymes, artificial organelles, and artificial mammalian cells. Each aspect will be briefly introduced, followed by highlighting efforts that considered key properties of the different mimics. Finally, the current challenges and opportunities will be outlined. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology

Polymer -lipid hybrid vesicles are an emerging type of nano-assemblies that show potential as artificial organelles among others. Phospholipids and poly(cholesteryl methacrylate)-blockpoly(methionine methacryloyloxyethyl ester (METMA) -random -2-carboxyethyl acrylate (CEA)) labeled with a FRET reporter pair is used for the assembly of small and giant hybrid vesicles with homogenous distribution of both building blocks in the membrane as confirmed by the FRET effect. These hybrid vesicles have no inherent cytotoxicity when incubated with HepG2 cells up to 1.1 x 10 11 hybrid vesicles per mL, and they are internalized by the cells. In contrast to the fluorescent signal ocoming from the block copolymer, the fluorescent signal originating from the lipids was barely detectable in cells incubated with hybrid vesicles for 6 h followed by 24 h in cell media, suggesting that the two building blocks have a different intracellular fate. These findings provide important insight in the design criteria of artificial organelles with potential structural integrity.Bottom-up assembled (semi)synthetic entities that interact with mammalian cells and tissue is an emerging approach, which aims to replace missing or lost cellular function as well as to integrate non-native activity. A diversity of cellular and subcellular structural assemblies (e.g., artificial cells [1] and artificial organelles [2] , synthetic biomolecules (e.g., nanozymes [3] ) and biological functions (e.g., locomotion, [4] fusion, [5] catalytic conversion [6] etc.) are being considered.