Ultrathin Covalently Bound Organic Layers on Mica: Formation of Atomically Flat Biofunctionalizable Surfaces

Tough and Alkaline-Resistant Mussel-Inspired Wet Adhesion with Surface Salt Displacement via Polydopamine/Amine Synergy

The mussel-inspired catechol-based strategy has been well recognized as a promising alternative to design and exploit new generation adhesive materials applicable in many fields, ranging from biomedical adhesives to coatings of biomedical devices and engineering applications. However, in situ achievement of tough adhesion capability to substrate surfaces (e.g., minerals) is severely limited under the physiological environment or seawater condition (namely, relatively high salinity and mild alkalinity). In this work, a facile and versatile approach is proposed to in situ achieve robust wet adhesion in aqueous solutions of high salinity and mild alkalinity, via integrating primary amines into mussel-inspired polydopamine (PDA). By using a surface forces apparatus (SFA), the corresponding interaction behaviors have been systematically investigated. The strong wet adhesion was demonstrated and achieved via a synergetic effect of amine and PDA to the wet surfaces, including the surface salt displacement assisted by primary amine, strong adhesion to substrates facilitated by the catechol groups on PDA moieties, and enhanced cohesion through their cation-π interactions. Our results provide useful insights into the design and development of high-performance underwater adhesives and water-resistance materials.

Quantitative and Orthogonal Formation and Reactivity of SuFEx Platforms

The constraints of minute reactant amounts and the impossibility to remove any undesired surface‐bound products during monolayer functionalization of a surface necessitate the selection of efficient, modular and orthogonal reactions that lead to quantitative conversions. Herein, we explore the character of sulfur–fluoride exchange (SuFEx) reactions on a surface, and explore the applicability for quantitative and orthogonal surface functionalization. To this end, we demonstrate the use of ethenesulfonyl fluoride (ESF) as an efficient SuFEx linker for creating “SuFEx‐able” monolayer surfaces, enabling three distinct approaches to utilize SuFEx chemistry on a surface. The first approach relies on a di‐SuFEx loading allowing dual functionalization with a nucleophile, while the two latter approaches focus on dual (CuAAC–SuFEx/SPOCQ–SuFEx) click platforms. The resultant strategies allow facile attachment of two different substrates sequentially on the same platform. Along the way we also demonstrate the Michael addition of ethenesulfonyl fluoride to be a quantitative surface‐bound reaction, indicating significant promise in materials science for this reaction.

ortho-Quinones and Analogues Thereof: Highly Reactive Intermediates for Fast and Selective Biofunctionalization

Fast, selective and facile functionalization of biologically relevant molecules is a pursuit of ever‐growing importance. A promising approach in this regard employs the high reactivity of quinone and quinone analogues for fast conjugation chemistry by nucleophilic addition or cycloadditions. Combined with in situ generation of these compounds, selective conjugation on proteins and surfaces can be uniquely induced in a time and spatially resolved manner: generation of a quinone can often be achieved by simple addition of an enzyme or stoichiometric amounts of chemoselective oxidant, or by exposure to light. In this Minireview, we discuss the generation and subsequent functionalization of quinones, iminoquinones, and quinone methides. We also discuss practical applications regarding these conjugation strategies.

Approach Matters: The Kinetics of Interfacial Inverse-Electron Demand Diels-Alder Reactions

Rapid and quantitative click functionalization of surfaces remains an interesting challenge in surface chemistry. In this regard, inverse electron demand Diels-Alder (IEDDA) reactions represent a promising metal-free candidate. Herein, we reveal quantitative surface functionalization within 15 min. Furthermore, we report the comprehensive effects of substrate stereochemistry, surrounding microenvironment and substrate order on the reaction kinetics as obtained by surface-bound mass spectrometry (DART-HRMS).