Nanothin Coculture Membranes with Tunable Pore Architecture and Thermoresponsive Functionality for Transfer-Printable Stem Cell-Derived Cardiac Sheets

Coculturing stem cells with the desired cell type is an effective method to promote the differentiation of stem cells. The features of the membrane used for coculturing are crucial to achieving the best outcome. Not only should the membrane act as a physical barrier that prevents the mixing of the cocultured cell populations, but it should also allow effective interactions between the cells. Unfortunately, conventional membranes used for coculture do not sufficiently meet these requirements. In addition, cell harvesting using proteolytic enzymes following coculture impairs cell viability and the extracellular matrix (ECM) produced by the cultured cells. To overcome these limitations, we developed nanothin and highly porous (NTHP) membranes, which are ∼20-fold thinner and ∼25-fold more porous than the conventional coculture membranes. The tunable pore size of NTHP membranes at the nanoscale level was found crucial for the formation of direct gap junctions-mediated contacts between the cocultured cells. Differentiation of the cocultured stem cells was dramatically enhanced with the pore size-customized NTHP membrane system compared to conventional coculture methods. This was likely due to effective physical contacts between the cocultured cells and the fast diffusion of bioactive molecules across the membrane. Also, the thermoresponsive functionality of the NTHP membranes enabled the efficient generation of homogeneous, ECM-preserved, highly viable, and transfer-printable sheets of cardiomyogenically differentiated cells. The coculture platform developed in this study would be effective for producing various types of therapeutic multilayered cell sheets that can be differentiated from stem cells

Magnetically Separable Microporous Fe–Porphyrin Networks for Catalytic Carbene Insertion into N–H Bonds

Microporous organic networks (MONs) are a new class of porous materials. This work shows the application of MON chemistry for the preparation of magnetically separable catalytic systems. By the Sonogashira coupling of Fe^III–tetrakis­(4-ethynylphenyl)­porphyrin and 1,4-diiodobenzene, Fe₃O₄ nanoparticles were coated successfully with Fe–porphyrin networks. The average thickness of the homogeneous coating was ∼17 nm. According to the powder X-ray diffraction and N₂ isotherm analyses, the Fe–porphyrin network coating exhibited amorphous and microporous characteristics. The microporous Fe–porphyrin networks on the Fe₃O₄ nanoparticles showed good catalytic performance for carbene insertion into the N–H bond of amines. The catalytic systems were easily recycled from the reaction mixture by magnetic separation. We believe that the synthetic strategy in this work can be extended to the various catalytic systems

Cooperative Catechol-Functionalized Polypept(o)ide Brushes and Ag Nanoparticles for Combination of Protein Resistance and Antimicrobial Activity on Metal Oxide Surfaces

Prevention of biofouling and microbial contamination of implanted biomedical devices is essential to maintain their functionality and biocompatibility. For this purpose, polypept­(o)­ide block copolymers have been developed, in which a protein-resistant polysarcosine (pSar) block is combined with a dopamine-modified poly­(glutamic acid) block for surface coating and silver nanoparticles (Ag NPs) formation. In the development of a novel, versatile, and biocompatible antibacterial surface coating, block lengths pSar were varied to derive structure–property relationships. Notably, the catechol moiety performs two important tasks in parallel; primarily it acts as an efficient anchoring group to metal oxide surfaces, while it furthermore induces the formation of Ag NPs. Attributing to the dual function of catechol moieties, antifouling pSar brush and antimicrobial Ag NPs can not only adhere stably on metal oxide surfaces, but also display passive antifouling and active antimicrobial activity, showing good biocompatibility simultaneously. The developed strategy seems to provide a promising platform for functional modification of biomaterials surface to preserve their performance while reducing the risk of bacterial infections