Color Bricks: Building Highly Organized and Strongly Absorbing Multicomponent Arrays of Terpyridyl Perylenes on Metal Oxide Surfaces

Terpyridine‐substituted perylenes containing cyclic anhydrides in the peri position were synthesized. The anhydride group served as an anchor for assembly of the terpyridyl‐crowned chromophores as monomolecular layers on metal oxide surfaces. Further coordination with Zn²⁺ ions allowed for layer‐by‐layer formation of supramolecular assemblies of perylene imides on the solid substrates. With properly selected anchor and linker molecules it was possible to build high quality structures of greater than ten successive layers by a simple and straightforward procedure. The prepared films were stable and had a broad spectral coverage and high absorbance. To demonstrate their potential use, the synthesized dyes were employed in solid‐state dye‐sensitized solar cells, and electron injection from the perylene antennas to titanium dioxide was observed.     

Recent Advancements in Using Polymers for Intestinal Mucoadhesion and Mucopenetration

Oral administration of actives is the most desired form of delivery, but the formulations need to overcome a variety of barriers including the intestinal mucus. This feature article summarizes the developments from the past 2–3 years in this context focusing on polymer‐based formulations. The progress in assembling mucopenetrating nanoparticles is outlined considering coatings using noninteracting polymers as well as virus‐like particles and charge‐shifting particles. Next, polymers and their modification to enhance mucoadhesion are discussed, followed by providing examples of double‐encapsulation systems that aim to combine mucopenetration with mucoadhesion in the same formulation. Finally, a short outlook is provided highlighting a few of the most pressing challenges to address.     

Iodine(I) and Silver(I) Complexes of Benzoimidazole and Pyridylcarbazole Derivatives

The synthesis of iodine(I) complexes with either benzoimidazole or carbazole-derived sp² N-containing Lewis bases is described, as well as their corresponding silver(I) complexes. The addition of elemental iodine to the linear two-coordinate Ag(I) complexes produces iodine(I) complexes with a three-center four-electron (3c–4e) [N−I−N]⁺ bond. The ¹H and ¹H-¹⁵N HMBC NMR studies unambiguously confirm the formation of the complexes in all cases via the [N−Ag−N]⁺→[N−I−N]⁺ cation exchange, with the ¹⁵N NMR chemical shift change between 94 to 111 ppm when compared to the free ligand. The single crystal X-ray crystallographic studies on eight I⁺ complexes revealed highly symmetrical [N−I−N]⁺ bonds with I−N bond distances of 2.21–2.26 Å and N−I−N angles of 177–180°, whilst some of the corresponding Ag⁺ complexes showed a clear deviation from linearity with N−Ag−N angles of ca. 150° and Ag−N bond distances of 2.09–2.18 Å.     

Synthesis of porphyrinoids with silane anchors and their covalent self-assembling and metallation on solid surface

We have synthesized a set of porphyrin and phthalocyanine compounds with two different silane anchors. Syntheses of the anchor-substituted chromophores have been carried out via hydrosilylation of alkene derivatives, catalyzed by platinum complexes. The reduction side-process was suppressed using specific anchor/catalyst pairs, and the silane-containing compounds were successfully isolated from hydrogenated by-products in pure form with good yields. The target porphyrinoids having stable reactive silane anchors possess the ability to self-assemble on metal oxides and quartz surfaces and optical fibers. Covalent attachment is done in one-step, which makes the bonding process fast and easy. Immobilized chromophores were further converted by on-surface reactions into Zn(II) and Mg(II) metal complexes. The metallation time was found to be as fast as 1 min for Zn ion. Bonding densities calculated from the absorbances of the deposited layers give rough estimations for packing of the molecules on various substrates and evidence for monomolecular layers formation.     

Intracorneal Implantation of 3D Bioprinted Scaffolds Containing Mesenchymal Stromal Cells Using Femtosecond-Laser-Assisted Intrastromal Keratoplasty

Injury of the cornea is a complex biological process. Regeneration of the corneal stroma can be facilitated by the presence of mesenchymal stromal cells (MSCs) and application of tissue equivalents. A new tissue-engineering strategy for corneal stroma regeneration is presented using cellularized 3D bioprinted hydrogel constructs implanted into organ cultured porcine corneas using femtosecond laser-assisted intrastromal keratoplasty. The ex vivo cultured, MSC-loaded 3D bioprinted structures remain intact, support cell survival, and contain de novo synthesized extracellular matrix components and migrating cells throughout the observation period. At day 14 postimplantation, the cellularized tissue equivalents contain few or no cells, as demonstrated by optical coherence tomography imaging and immunofluorescent staining. This study successfully combines a laboratory-based method with modern, patient-care practice to produce a cell-laden tissue equivalent for corneal implantation. Optimal bioink composition and cellularization of tissue equivalents are essential in fine-tuning a method to promote the current technique as a future treatment modality.