Fabrication of unique chemical patterns and concentration gradients with visible light.

A modular and general method based on a photomediated ATRA reaction for the spatially controlled functionalization of surfaces with visible light is reported. The ability to control reactivity with light intensity combined with the orthogonality of ATRA chemistry allows well-defined chemically differentiated monolayers and complex nonlinear chemical concentration gradients to be easily prepared. Use of light to mediate these reactions permits spatial regulation and the generation of unique, multifunctional chemical gradients

Clipping de 21/03/2018

Clipping de 21/03/2018: A crise civilizatória / Jéferson Dantas / Professor / Doutor em Educação / Oportunidade / Cheesecake Labs / Aplicativos / Startups / Expectativa / UFSC / Sistemas de Informação / Estudantes / Comissão de Transportes / Alesc / Palestra / Ônibus elétrico / Mutirão de avaliação das funções visuais em bebês será realizado no Arroio / Profissionais formados / Graduandos / Fisioterapia / Balneário Arroio do Silva / Programa de Pós-Graduação em Ciências da Reabilitação / Secretaria de Saúde / Fisioterapeuta e Mestranda / Giovana Pascoali Rodovanski / Terapias alternativas / Exercício físico supervisionado / Funções visuais / Bebês / Marcelo Câmara / Polifarmáci

Fabrication of Unique Chemical Patterns and Concentration Gradients with Visible Light

A modular and general method based on a photomediated ATRA reaction for the spatially controlled functionalization of surfaces with visible light is reported. The ability to control reactivity with light intensity combined with the orthogonality of ATRA chemistry allows well-defined chemically differentiated monolayers and complex nonlinear chemical concentration gradients to be easily prepared. Use of light to mediate these reactions permits spatial regulation and the generation of unique, multifunctional chemical gradients

Interfacial Adhesion of Fully Transient, Mussel‐Inspired Hydrogels with Different Network Crosslink Modalities

In fully transient, mussel-inspired hydrogels, metal-coordinate complexes form supramolecular crosslinks, which offer tunable viscoelastic properties and mechanical reversibility. The metal-coordination complexation that comprises the crosslinks can take on tris-, bis-, mono-, and free-state modalities (3, 2, 1, or 0 ligands per ion, respectively). Although prior work has established relationships between network crosslinking and mechanical properties, the effect of crosslink and ligand modalities on gel-surface adhesion is not well understood for fully transient hydrogels. Using glass and nickel-coated spherical probes, the effect of network crosslinking modalities on the adhesive strength of hydrogels based on histidine-Ni2+ and nitrodopamine-Fe3+ ion crosslinks is investigated. Since crosslink modalities have a strong impact on the mechanical properties of the bulk network, it is first determined how adhesion relates to the mechanical properties, regardless of the distribution of crosslinking modalities and ligand type. It is ultimately found that the peak adhesive stress increases with decreasing percentage of ligands in tris-crosslinks

Control of hierarchical polymer mechanics with bioinspired metal-coordination dynamics

In conventional polymer materials, mechanical performance is traditionally engineered via material structure, using motifs such as polymer molecular weight, polymer branching, or copolymer-block design(1). Here, by means of a model system of 4-arm poly(ethylene glycol) hydrogels crosslinked with multiple, kinetically distinct dynamic metal-ligand coordinate complexes, we show that polymer materials with decoupled spatial structure and mechanical performance can be designed. By tuning the relative concentration of two types of metal-ligand crosslinks, we demonstrate control over the material’s mechanical hierarchy of energy-dissipating modes under dynamic mechanical loading, and therefore the ability to engineer a priori the viscoelastic properties of these materials by controlling the types of crosslinks rather than by modifying the polymer itself. This strategy to decouple material mechanics from structure may inform the design of soft materials for use in complex mechanical environments