Chemically Induced Vinylphosphonothiolate Electrophiles for Thiol-Thiol Bioconjugations.

Herein we introduce vinylphosphonothiolates as a new class of cysteine-selective electrophiles for protein labeling and the formation of stable protein-protein conjugates. We developed a straightforward synthetic route to convert nucleophilic thiols into electrophilic, thiol-selective vinylphosphonothiolates: In this protocol, intermediately formed disulfides can be chemoselectively substituted with vinylphosphonites under acidic conditions to yield the desired vinylphosphonothiolates. Notably, this reaction sequence enables the installation of vinylphosphonothiolate electrophiles directly on cysteine side chains within peptides and proteins. In addition to labeling the monoclonal antibody trastuzumab with excellent cysteine-selectivity, we applied our protocol for the site-specific conjugation of two proteins with unique cysteine residues yielding a nonhydrolyzable phosphonothiolate-linked diubiquitin and an ubiquitin-α-synuclein conjugate. The latter was recognized as a substrate in a subsequent enzymatic ubiquitination reaction.

Lowering the Healing Temperature of Photoswitchable Dynamic Covalent Polymer Networks.

To reduce the environmental footprint of the modern society, it is desirable to elongate the lifetime of consumer products, for example by implementing healable coatings and protective layers. However, since most healing processes carried out by heat or light suffer from material degradation, improving the robustness and integrity of healable materials is of tremendous importance to prolong their lifetime. In recent work, a prototype is created of a dynamic covalent polymer network, whose thermal healing ability can be switched "on" and "off" by light to provide a means to locally control repair of a damaged coating. Based on the initial concept, herein a new set of difunctional crosslinkers and linear polymers of various compositions is presented to form dynamic covalent polymer networks, in which the barrier for the retro Diels-Alder decrosslinking reaction is decreased. The approach results in lower healing temperatures and thus a longer lifetime of the material.