Materials engineered to elicit targeted cellular responses in regenerative medicine must display bioligands with precise spatial and temporal control. Although materials with temporally regulated presentation of bioadhesive ligands using external triggers, such as light and electric fields, have been recently realized for cells in culture, the impact of in vivo temporal ligand presentation on cell-material responses is unknown. Here, we present a general strategy to temporally and spatially control the in vivo presentation of bioligands using cell adhesive peptides with a protecting group that can be easily removed via transdermal light exposure to render the peptide fully active. We demonstrate that non-invasive, transdermal time-regulated activation of cell-adhesive RGD peptide on implanted biomaterials regulates in vivo cell adhesion, inflammation, fibrous encapsulation, and vascularization of the material. This work shows that triggered in vivo presentation of bioligands can be harnessed to direct tissue reparative responses associated with implanted biomaterials.

Mussel glue: Bioinspired underwater chemical bonding with the possibility of phototriggered debonding is reported. A four-arm star-poly(ethyleneglycol) endfunctionalized by nitrodopamine was synthesized. The nitrodopamine offered the reactivity of catechol and the chemistry of the photocleavable o-nitrophenyl ethyl group (see picture).

Inspired by the amino acid 2‐chloro‐4,5‐dihydroxyphenylalanine (Cl‐DOPA), present in the composition of the proteinaceous glue of the sandcastle worm Phragmatopoma californica, a simple strategy is presented to confer antifouling properties to polymer surfaces using (but not releasing) a bioinspired biocide. Cl‐Dopamine is used to functionalize polymer materials and hydrogel films easily, to prevent biofilm formation on them.

The curing time of an adhesive material is determined by the polymerization and cross-linking kinetics of the adhesive formulation and needs to be optimized for the particular application. Here, we explore the possibility of tuning the polymerization kinetics and final mechanical properties of tissue-adhesive PEG gels formed by polymerization of end-functionalized star-PEGs with catecholamines with varying substituents. We show strong differences in cross-linking time and cohesiveness of the final gels among the catecholamine-PEG variants. Installation of an electron-withdrawing but π-electron donating chloro substituent on the catechol ring resulted in faster and more efficient cross-linking, while opposite effects were observed with the strongly electron-withdrawing nitro group. Chain substitution slowed down the kinetics and hindered cross-linking due either to chain breakdown (β-OH group, in norepinephrine) or intramolecular cyclization (α-carboxyl group, in DOPA). Interesting perspectives derive from use of mixtures of catecholamine-PEG precursors offering further opportunities for fine-tuning of the curing parameters. These are interesting properties for the application of catecholamine-PEG gels as tissue glues or biomaterials for cell encapsulation.

Der Klebstoff von Muscheln: Eine bioinspirierte chemische Verklebung wird vorgestellt, die unter Wasser geknüpft und durch Bestrahlung mit Licht wieder gelöst werden kann. Zu diesem Zweck wurde ein vierarmiges Polyethylenglycol‐Sternpolymer mit Nitrodopamin‐Endgruppen bestückt, die zum einen als 1,2‐Dihydroxybenzol reagieren und zum anderen als photospaltbare o‐Nitrophenylethyl‐Gruppe wirken (siehe Bild).

The influence of 6-chloro and 6-nitro substituents on the thickness, homogeneity, and general properties of coatings produced by controlled oxidative polymerization of dopamine and its beta-hydroxy derivative, norepinephrine, is investigated. Substitution at the catecholamine 6-position affects the deposition kinetics due to modification of the oxidation potential of the catechol groups. Increasing the hydroxyl group acidity results likewise in changes in pH response and water uptake. A similar trend with pH is also observed in covalently crosslinked catechol-functionalized PEG-hydrogels, while an opposite behavior is measured in metal crosslinked films. These results pave the way toward the definition of structure-property relationships based on dopamine substitution effects in polycatecholamine layers and derived polymers

This work was inspired by a previous report [Janjua, M. R. S. A. Inorg. Chem. 2012, 51, 11306–11314] in which the optoelectronic properties were improved with an acceptor bearing heteroaromatic rings. Herein, we have designed four novel Y-series non-fullerene acceptors (NFAs) by end-capped acceptor modifications of a recently synthesized 15% efficient Y21 molecule for better optoelectronic properties and their potential use in solar cell applications. Density functional theory (DFT) along with time-dependent density functional theory (TDDFT) at the B3LYP/6-31G(d,p) level of theory is used to calculate the band gap, exciton binding energy along with transition density matrix (TDM) analysis, reorganizational energy of electrons and holes, and absorption maxima and open-circuit voltage of investigated molecules. In addition, the PM6:YA1 complex is also studied to understand the charge shifting from the donor polymer PM6 to the NFA blend. Results of all parameters suggest that the DA’D electron-deficient core and effective end-capped acceptors in YA1–YA4 molecules form a perfect combination for effective tuning of optoelectronic properties by lowering frontier molecular orbital (FMO) energy levels, reorganization energy, and binding energy and increasing the absorption maximum and open-circuit voltage values in selected molecules ( YA1–YA4) . The combination of extended conjugation and excellent electron-withdrawing capability of the end-capped acceptor moiety in YA1 makes YA1 an excellent organic solar cell (OSC) candidate owing to promising photovoltaic properties including the lowest energy gap (1.924 eV), smallest electron mobility (λ e = 0.0073 eV) and hole mobility (λ h = 0.0083 eV), highest λ max values (783.36 nm (in gas) and 715.20 nm (in chloroform) with lowest transition energy values ( E x ) of 1.58 and 1.73 eV, respectively), and fine open-circuit voltage ( V oc = 1.17 V) with respect to HOMO PM6 –LUMO acceptor . Moreover, selected molecules are observed to have better photovoltaic properties than Y21 , thus paving the way for experimentalists to look for future developments of Y-series-based highly efficient solar cells.

No abstract