Naked-Eye Thiol Analyte Detection via Self-Propagating, Amplified Reaction Cycle.

We present an approach for detecting thiol analytes through a self-propagating amplification cycle that triggers the macroscopic degradation of a hydrogel scaffold. The amplification system consists of an allylic phosphonium salt that upon reaction with the thiol analyte releases a phosphine, which reduces a disulfide to form two thiols, closing the cycle and ultimately resulting in exponential amplification of the thiol input. When integrated in a disulfide cross-linked hydrogel, the amplification process leads to physical degradation of the hydrogel in response to thiol analytes.

Enhancing the ROS Sensitivity of a Responsive Supramolecular Hydrogel Using Peroxizyme Catalysis.

Hydrogels that can disintegrate upon exposure to reactive oxygen species (ROS) have the potential for targeted drug delivery to tumor cells. In this study, we developed a diphenylalanine (FF) derivative with a thioether phenyl moiety attached to the N-terminus that can form supramolecular hydrogels at neutral and mildly acidic pH. The thioether can be oxidized by ROS to the corresponding sulfoxide, which makes the gelator hydrolytically labile.

Temporally programmed polymer - solvent interactions using a chemical reaction network.

Out of equilibrium operation of chemical reaction networks (CRNs) enables artificial materials to autonomously respond to their environment by activation and deactivation of intermolecular interactions. Generally, their activation can be driven by various chemical conversions, yet their deactivation to non-interacting building blocks remains largely limited to hydrolysis and internal pH change. To achieve control over deactivation, we present a new, modular CRN that enables reversible formation of positive charges on a tertiary amine substrate, which are removed using nucleophilic signals that control the deactivation kinetics.

Thioanisole ester based logic gate cascade to control ROS-triggered micellar degradation.

In certain tumor and diseased tissues, reactive oxygen species (ROS), such as HO, are produced in higher concentrations than in healthy cells. Drug delivery and release systems that respond selectively to the presence of ROS, while maintaining their stability in "healthy" biological conditions, have great potential as on-site therapeutics. This study presents polymer micelles with 4-(methylthio)phenyl ester functionalities as a ROS-responsive reactivity switch.

Indoline Catalyzed Acylhydrazone/Oxime Condensation under Neutral Aqueous Conditions.

Acylhydrazones formation has been widely applied in materials science and biolabeling. However, their sluggish condensation rate under neutral conditions limits its application. Herein, indolines with electron-donating groups are reported as a new catalyst scaffold, which can catalyze acylhydrazone, hydrazone, and oxime formation via an iminium ion intermediate.

Unexpected Racemization in the Course of the Acetalization of (+)-()-5-Methyl-Wieland-Miescher Ketone with 1,2-Ethanediol and TsOH under Classical Experimental Conditions.

(+)-() and (-)-()-5-methyl-Wieland-Miescher ketone (+)- and (-)-, are important synthons in the diastereo and enantioselective syntheses of biological and/or pharmacological interesting compounds. A key step in these syntheses is the chemoselective C(1)O acetalization to (+)- and (-)-, respectively. Various procedures for this transformation have been described in the literature.