Monodisperse Hyperbranched Polytriazoles as Unimolecular Nanocontainers for Encapsulation of Functional Payloads.

In this work, a series of polytriazole-based unimolecular nanocontainers (UNs) with good water solubility, uniformity, and colloidal stability via a bottom-up chain-growth copper-catalyzed azide-alkyne cycloaddition (co)polymerization that features tunable size, degree of branching (DB), and functionality of the UNs is developed. A broad selection of hydrophobic payload molecules, including Nile red (NR), camptothecin, pyrene, 1-pyrenemethanol, and IR676, are successfully encapsulated to demonstrate the high versatility of these polymers as UNs. Using NR as a probe guest, the relationship between the encapsulation performance and the structural properties of UNs, including size and DB, is investigated. Furthermore, the localization and dispersity of encapsulated NR are explored and the dependence of payload's dispersity on the DB of UNs is revealed. The payload encapsulated in UNs exhibits tunable release kinetics, determined by either adjusting release conditions or including pH-responsive structural units in the UNs. Meanwhile, the dyes encapsulated in UNs exhibit improved photostability and stronger resistance to photobleaching. It is expected that these explorations address the size and stability issues widely encounter in current drug/dye nanocarriers and provide a versatile platform of polytriazole-based UNs for suitable payloads in various applications, including drug delivery and bio-imaging.

Tunable Luminescence and Enhanced Polar Solvent Resistance of Perovskite Nanocrystals Achieved by Surface-Initiated Photopolymerization.

Colloidal lead halide perovskite nanocrystals (PNCs) have demonstrated great potential as materials of light-emitting diodes if their colloidal and compositional instability could be addressed. Herein, we reported a facile surface-initiated photopolymerization method that introduced polymers on a CsPbBr3 PNC surface to achieve improved stability and regulated halide exchange of PNCs in polar solvents. Synthetic polymers grafted from the surface of an individual PNC surface stabilized the PNCs, in which the multidentate linkage initiators and the extending polymers were two essential factors. The polymer-grafted PNCs showed composition-dependent colloidal dispersity and structural stability in various polar organic solvents and aqueous condition. It was found that changing the polarity of dispersing solvents effectively switched the swelling and collapsed states of surface polymers on the PNC-polymer nanoparticles, which provided an on-off mechanism to regulate the permeation of halide anions into the PNC cores. Thus, halide exchange of polymer-grafted PNCs in a good solvent for polymers varied the composition of PNCs and their emissive color, while switching the nanoparticles into a poor solvent, for example, ethanol and water, collapsed the surface polymer, prohibited the halide exchange, and consequently retained the color stability. It was demonstrated that different CsPbX3 PNCs with collapsed surface polymers could coexist into one solvent medium, achieving simultaneous emission with a white display. We believe this work provided insights into the rational functionalization of PNC materials using well-defined synthetic polymers toward tunable emission and outstanding stability in polar media.

Magnetic Nanoplatforms for Covalent Protein Immobilization Based on Spy Chemistry.

Immobilization of proteins on magnetic nanoparticles (MNPs) is an effective approach to improve protein stability and facilitate separation of immobilized proteins for repeated use. Herein, we exploited the efficient SpyTag-SpyCatcher chemistry for conjugation of functional proteins onto MNPs and established a robust magnetic-responsive nanoparticle platform for protein immobilization. To maximize the loading capacity and achieve outstanding water dispersity, the SpyTag peptide was incorporated into the surface-charged polymers of MNPs, which provided abundant active sites for Spy chemistry while maintaining excellent colloidal stability in buffer solution. Conjugation between enhanced green fluorescence protein (EGFP)-SpyCatcher-fused proteins and SpyTag-functionalized MNPs was efficient at ambient conditions without adding enzymes or chemical cross-linkers. Benefiting from the excellent water dispersity and interface compatibility, the surface Spy reaction has fast kinetics, which is comparable to that of the solution Spy reaction. No activity loss was observed on EGFP after conjugation due to the site-selective nature of Spy chemistry. The immobilization process of EGFP on MNPs was highly specific and robust, which was not affected by the presence of other proteins and detergents, such as bovine serum albumin and Tween 20. The MNP platform was demonstrated to be protective to the conjugated EGFP and significantly improved the shelf life of immobilized proteins. In addition, experiments confirmed the retained magnetophoresis of the MNP after protein loading, demonstrating fast MNP recovery under an external magnetic field. This MNP is expected to provide a versatile and modular platform to achieve effective and specific immobilization of other functional proteins, enabling easy reuse and storage.