Janus Nanoparticle Coupled Double-Network Hydrogel.

For double network (DN) hydrogels, their performance can be tuned by adjusting the interaction between their two networks. A novel DN hydrogel toughening approach is proposed by employing Janus nanoparticles (JNs) as crosslinkers to gain a conjoined-network hydrogel. First, a kind of JNs modified by amino groups and quaternary ammonium salt is synthesized, named R3 N+ -JN-NH2 . The DN hydrogel is fabricated based on ionic coordination between calcium chloride (CaCl2 ) and sodium alginate (Alg), as well as covalent (benzoic imine) between glycol chitosan (GC) and benzaldehyde-capped poly(ethylene oxide) (BzCHO-PEO-BzCHO). Based on the same covalent and ionic dynamic crosslinking mechanism, the added R3 N+ -JN-NH2 interacts with two networks to promote crosslinking to form a dually crosslinked structure. The R3 N+ -JN-NH2 effectively provides more energy dissipation, and the hydrogel with conjoined networks shows better compression resistance.

Affinity-Guided Oxime Chemistry for Selective Protein Acylation in Live Tissue Systems.

Catalyst-mediated protein modification is a powerful approach for the imaging and engineering of natural proteins. We have previously developed affinity-guided 4-dimethylaminopyridine (AGD) chemistry as an efficient protein modification method using a catalytic acyl transfer reaction. However, because of the high electrophilicity of the thioester acyl donor molecule, AGD chemistry suffers from nonspecific reactions to proteins other than the target protein in crude biological environments, such as cell lysates, live cells, and tissue samples. To overcome this shortcoming, we here report a new acyl donor/organocatalyst system that allows more specific and efficient protein modification. In this method, a highly nucleophilic pyridinium oxime (PyOx) catalyst is conjugated to a ligand specific to the target protein. The ligand-tethered PyOx selectively binds to the target protein and facilitates the acyl transfer reaction of a mild electrophilic N-acyl-N-alkylsulfonamide acyl donor on the protein surface. We demonstrated that the new catalytic system, called AGOX (affinity-guided oxime) chemistry, can modify target proteins, both in test tubes and cell lysates, more selectively and efficiently than AGD chemistry. Low-background fluorescence labeling of the endogenous cell-membrane proteins, carbonic anhydrase XII and the folate receptor, in live cells allowed for the precise quantification of diffusion coefficients in the protein's native environment. Furthermore, the excellent biocompatibility and bioorthogonality of AGOX chemistry were demonstrated by the selective labeling of an endogenous neurotransmitter receptor in mouse brain slices, which are highly complicated tissue samples.

Semisynthetic lectin-4-dimethylaminopyridine conjugates for labeling and profiling glycoproteins on live cell surfaces.

Glycoproteins on cell surfaces play important roles in biological processes, including cell-cell interaction/signaling, immune response, and cell differentiation. Given the diversity of the structure of glycans, labeling and imaging of selected glycoproteins are challenging, although several promising strategies have been developed recently. Here, we design and construct semisynthetic reactive lectins (sugar-binding proteins) that are able to selectively label glycoproteins. Congerin II, an animal galectin, and wheat germ agglutinin are conjugated with 4-dimethylaminopyridine (DMAP), a well-known acyl transfer catalyst by our affinity-guided DMAP method and Cu(I)-assisted click chemistry. Selective labeling of glycoproteins is facilitated by the DMAP-tethered lectin catalysts both in vitro and on living cells. Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) analysis enabled us to isolate labeled glycoproteins that are uniquely exposed on distinct cell lines. Furthermore, the combination of immunoprecipitation with mass spectrometry (MS)-fingerprinting techniques allowed us to characterize 48 glycoproteins endogenously expressed on HeLa cells, and some low-abundant glycoproteins, such as epidermal growth factor receptor (EGFR) and neuropilin-1, were successfully identified. Our results demonstrate that semisynthetic DMAP-tethered lectins provide a new tool for labeling and profiling glycoproteins on living cells.

Photocorrosion-Based BiOCl Photothermal Materials for Synergistic Solar-Driven Desalination and Photoelectrochemistry Energy Storage and Release.

Solar-driven interfacial evaporation is one of the most promising desalination technologies. However, few studies have effectively combined energy storage with evaporation processes. Here, a novel multifunctional interfacial evaporator, calcium alginate hydrogel/bismuth oxychloride/carbon black (HBiC), is designed, which integrates the characteristics of interfacial evaporation and direct photoelectric conversion. Under illumination, the Bi nanoparticles which were produced by photoetching of BiOCl and its reaction heat are simultaneously used for the heating of water molecules. Meanwhile, part of the solar energy is converted into chemical energy through the photocorrosion reaction and stored in HBiC. At night, Bi NPs undergo autooxidation reaction and an electric current is generated during this process (like a metal-air battery), in which the maximum current density is more than 15 µA cm-2. This scientific design cleverly combines desalination with power generation and provides a new development direction for energy collection and storage.

An ideal catalyst carrier: patchy nanoparticles with dual functional domains of substrate enrichment and catalysis.

Enriching substrates near catalysts is an effective strategy to improve heterogeneous catalytic performance. The surface of PMMA@PIL-PA patchy nanoparticles is segmented into PMMA and PIL-PA domains. The hydrophobic PMMA domain can enrich water-insoluble substrates, while the hydrophilic PIL-PA one catalyzes the reaction of water-soluble and water-insoluble substrates in close proximity. The special patchy nanoparticles with both a hydrophobic substrate warehouse and catalysis functional divisions can effectively improve the catalytic efficiency. They were employed to catalyze the acetal reaction between water-insoluble benzaldehyde and water-soluble ethylene glycol by phosphotungstic acid (PA). Compared with the homo-nanoparticles, the conversion rate was greatly improved.