Tf2O/2-Chloropyridine-Triggered Synthesis of Benzo[b]thiophene 1,1-Dioxides from Sulfonium α-Acyl Sulfonylmethylides.

Triflic anhydride and 2-chloropyridine-comediated tandem activation, intramolecular aromatic electrophilic addition, and 1,2-sulfonyl shift via spirocyclic intermediates of sulfonium α-acyl sulfonylmethylides realize the efficient synthesis of 2-alkyl/arylthiobenzo[b]thiophene 1,1-dioxides. The deactivated sulfonyl group determines the site-selectivity of the electrophilic addition via the ipso-attack, while the following S-migration controls the regioselectivity. Some of 2-methylthiobenzo[b]thiophene 1,1-dioxides show fluorescence properties in the solid state and in their solutions.

Demethyl oxidative halogenation of diacyl dimethylsulfonium methylides.

α-Halo-α-methylthio-ß-ketosulfones containing a quaternary halocarbon stereocenter were prepared via selective demethyl oxidative halogenations of diacyl dimethylsulfonium methylides in moderate to excellent yields (39 examples; up to 98%). The current protocols directly and efficiently introduce a halogen atom into organic compounds with high functional group tolerance under metal-free conditions.

Halide-promoted pyridinylation of α-acylmethylides with 2-halo-1-methylpyridinium iodides as reagents.

Halide-promoted pyridinylation between α-acyl sulfonylmethylides and 2-halo-1-methylpyridinium iodides in a transition-metal-free protocol is described. A broad range of α-acyl sulfonylmethylides were transformed to bifunctionalized vinylsulfones in moderate to good yields, thereby providing a facile and practical approach for constructing methylthio- and pyridinoxyl-substituted vinylsulfones. The substrates can be extended to other acyl methylides. The reaction was shown to entail the formation of a C-O bond and consecutive breaking of C-S, C-Cl and C-N bonds.

Self-assembled flagella protein nanofibers induce enhanced mucosal immunity.

Nanofibers are potential vaccines or adjuvants for vaccination at the mucosal interface. However, how their lengths affect the mucosal immunity is not well understood. Using length-tunable flagella (self-assembled from a protein termed flagellin) as model protein nanofibers, we studied the mechanisms of their interaction with mucosal interface to induce immune responses length-dependently. Briefly, through tuning flagellin assembly, length-controlled protein nanofibers were prepared. The shorter nanofibers exhibited more pronounced toll-like receptor 5 (TLR5) and inflammasomes activation accompanied by pyroptosis, as a result of cellular uptake, lysosomal damage, and mitochondrial reactive oxygen species generation. Accordingly, the shorter nanofibers elevated the IgA level in mucosal secretions and enhanced the serum IgG level in ovalbumin-based intranasal vaccinations. These mucosal and systematic antibody responses were correlated with the mucus penetration capacity of the nanofibers. Intranasal administration of vaccines (human papillomavirus type 16 peptides) adjuvanted with shorter nanofibers significantly elicited cytotoxic T lymphocyte responses, strongly inhibiting tumor growth and improving survival rates in a TC-1 cervical cancer model. This work suggests that length-dependent immune responses of nanofibers can be elucidated for designing nanofibrous vaccines and adjuvants for both infectious diseases and cancer.

Monosodium urate crystals with controlled shape and aspect ratio for elucidating the pathological progress of acute gout.

Gout is a self-limiting inflammatory arthritis mediated by the precipitation of monosodium urate (MSU) crystals that further activate the NLRP3 inflammasome and initiate a cascade of inflammatory events. However, the key physicochemical properties of MSU crystals that determine the acute phase of gout have not been fully identified. In this study, a library of engineered MSU crystals with well-controlled size and shape is designed to explore their proinflammatory potentials in mediating the pathological progress of gout. It is demonstrated that medium-sized long aspect ratio MSU crystals induce more prominent IL-1ß production in vitro due to enhanced cellular uptake and the production of mitochondrial reactive oxygen species (mtROS). The characteristics of MSU crystals are also correlated with their inflammatory potentials in both acute peritonitis and arthritis models. Furthermore, 2-hydroxypropyl-ß-cyclodextrin (HP-ß-CD) is demonstrated to inhibit MSU-induced oxidative burst by removing plasma membrane cholesterol. As a result, it attenuates the inflammatory responses both in vitro and in vivo. Additionally, antioxidant N-acetylcysteine (NAC) is shown to alleviate acute gouty symptom by suppressing oxidative stress. This study identifies the key physicochemical properties of MSU crystals that mediate the pathogenesis of gout, which sheds light on novel design strategies for the intervention of gout.

Virus-Like Particle-Templated Silica-Adjuvanted Nanovaccines with Enhanced Humoral and Cellular Immunity.

Virus-like particles (VLPs) are self-assembled viral proteins that represent a superior form of antigens in vaccine formulations. To enhance immunogenicity, adjuvants, especially the aluminum salts (Alum), are essentially formulated in VLP vaccines. However, Alum only induce biased humoral immune responses that limits further applications of VLP-based vaccines. To stimulate more balanced immunity, we, herein, develop a one-step strategy of using VLPs as the biotemplates to synthesize raspberry-like silica-adjuvanted VLP@Silica nanovaccines. Hepatitis B surface antigen (HBsAg) VLPs and human papillomavirus type 18 (HPV 18) VLPs are selected as model templates. Circular dichroism (CD) and affinity analyses demonstrate that HBsAg VLPs in the nanovaccines maintain their secondary structure and immunogenicity, respectively. VLP@Silica promote silica dissolution-induced lysosomal escape and cytosolic delivery of antigens, and enhance the secretion of both Th1 and Th2 type cytokines in murine bone marrow-derived dendritic cells (BMDCs). Additionally, they could improve antigen trafficking and mediate DC activation in draining lymph nodes (DLNs). Vaccination study demonstrate that both HBsAg VLP@Silica and HPV 18 VLP@Silica nanovaccines induce enhanced antigen-specific antibody productions and T-cell mediated adaptive immune responses. This design strategy can utilize VLPs derived from a diversity of viruses or their variants as templates to construct both prophylactic and therapeutic vaccines with improved immunogenicity.

Mechanistic understanding of the aspect ratio-dependent adjuvanticity of engineered aluminum oxyhydroxide nanorods in prophylactic vaccines.

Aluminum oxyhydroxide (AlOOH) adjuvants are widely used in human vaccines. However, the interaction mechanisms at the material-bio interface, and further understandings on physicochemical property-dependent modulation of the immune responses still remain uncertain. Herein, a library of AlOOH nanorods with well-defined aspect ratios is designed to explore the mechanisms of adjuvanticity. The aspect ratios of AlOOH nanorods were demonstrated to be intrinsically modulated by the hydroxide supersaturation level during crystal growth, leading to the differences in surface free energy (SFE). As a result, higher aspect ratio AlOOH nanoadjuvants with lower SFE exhibited more hydrophobic surface, resulting in more membrane depolarization, cellular uptake and dendritic cell (DC) activation. By using hepatitis B surface antigen (HBsAg) virus-like particles (VLPs) or SARS-CoV-2 spike protein receptor-binding domain (RBD) as model antigens, AlOOH nanorods with higher aspect ratio were determined to elicit more potent humoral immune responses, which could be attributed to the enhanced DC activation and the efficient antigen trafficking to the draining lymph nodes. Our findings highlight the critical role of aspect ratio of AlOOH nanorods in modulating adjuvanticity, and further provide a design strategy for engineered nanoadjuvants for prophylactic vaccines.

Engineered Hydroxyapatite Nanoadjuvants with Controlled Shape and Aspect Ratios Reveal Their Immunomodulatory Potentials.

Hydroxyapatite (HAP) has been formulated as adjuvants in vaccines for human use. However, the optimal properties required for HAP nanoparticles to elicit adjuvanticity and the underlying immunopotentiation mechanisms have not been fully elucidated. Herein, a library of HAP nanorods and nanospheres was synthesized to explore the effect of the particle shape and aspect ratio on the immune responses in vitro and adjuvanticity in vivo. It was demonstrated that long aspect ratio HAP nanorods induced a higher degree of cell membrane depolarization and subsequent uptake, and the internalized particles elicited cathepsin B release and mitochondrial reactive oxygen species generation, which further led to pro-inflammatory responses. Furthermore, the physicochemical property-dependent immunostimulation capacities were correlated with their humoral responses in a murine hepatitis B surface antigen immunization model, with long aspect ratio HAP nanorods inducing higher antigen-specific antibody productions. Importantly, HAP nanorods significantly up-regulated the IFN-γ secretion and CD107α expression on CD8+ T cells in immunized mice. Further mechanistic studies demonstrated that HAP nanorods with defined properties exerted immunomodulatory effects by enhanced antigen persistence and immune cell recruitments. Our study provides a rational design strategy for engineered nanomaterial-based vaccine adjuvants.

Microwave-accelerated and efficient synthesis of structurally diverse N-(2,2-diphenylvinyl)-ß-oxoamides.

N-(2,2-Diphenylvinyl)-ß-oxoamides are both the structural moiety of biologically active compounds and important synthetic intermediates. Structurally diverse N-(2,2-diphenylvinyl)-ß-oxoamides are prepared efficiently from 2-diazo-1,3-dicarbonyl compounds and N-alkyl-2,2-diphenylaziridines via an electrophilic ring opening reaction under two different reaction conditions of reflux and microwave irradiation. 2-Diazo-1,3-dicarbonyl compounds undergo the Wolff rearrangement under heating to generate α-oxoketenes, which electrophilically react with N-alkylaziridines to directly produce structurally diverse N-(2,2-diphenylvinyl)-ß-oxoamides in good to excellent yields under microwave irradiation. Microwave irradiation accelerates the reaction obviously and efficiently. Both 2-diazo-1,3-diketones and alkyl 2-diazo-3-oxoalkanoates work well. The reaction is catalyst-free and highly atom economical, involves only loss of nitrogen and does not require additives. The products are useful synthons for the convenient preparation of multisubstituted ß-lactam derivatives.

Construction of Stable Wide-Temperature-Range Proton Exchange Membranes by Incorporating a Carbonized Metal-Organic Frame into Polybenzimidazoles and Polyacrylamide Hydrogels.

Proton exchange membrane fuel cells (PEMFCs) are promising devices for clean power generation in fuel cell electric vehicles applications. The further request of high-efficiency and cost competitive technology make high-temperature proton exchange membranes utilizing phosphoric acid-doped polybenzimidazole be favored because they can work well up to 180 °C without extra humidifier. However, they face quick loss of phosphoric acid below 120 °C and resulting in the limits of commercialization. Herein UiO-66 derived carbon (porous carbon-ZrO2 ), comprising branched poly(4,4'-diphenylether-5,5'-bibenzimidazole) and polyacrylamide hydrogels self-assembly (BHC1-4) membranes for wide-temperature-range operation (80-160 °C) is presented. These two-phase membranes contained the hygroscopicity of polyacrylamide hydrogels improve the low-temperature proton conductivity, relatively enable the membrane to function at 80 °C. An excellent cell performance of BHC2 membrane with high peak power density of 265 and 656 mW cm-2 at both 80 and 160 °C can be achieved. Furthermore, this membrane exhibits high stability of frequency cold start-ups (from room temperature to 80 °C) and long-term cell test at 160 °C. The improvement of cell performance and stability of BHC2 membrane indicate a progress of breaking operated temperature limit in existing PEMFCs systems.

Engineering aluminum hydroxyphosphate nanoparticles with well-controlled surface property to enhance humoral immune responses as vaccine adjuvants.

Aluminum phosphate adjuvants play a critical role in human inactivated and subunit prophylactic vaccines. However, a major challenge is that the underlying mechanism of immune stimulation remains poorly understood, which impedes the further optimal design and application of more effective adjuvants in vaccine formulations. To address this, a library of amorphous aluminum hydroxyphosphate nanoparticles (AAHPs) is engineered with defined surface properties to explore the specific mechanism of adjuvanticity at the nano-bio interface. The results demonstrate that AAHPs could induce cell membrane perturbation and downstream inflammatory responses, with positively-charged particles showing the most significantly enhanced immunostimulation potentials compared to the neutral or negatively-charged particles. In a vaccine using Staphylococcus aureus (S. aureus) recombinant protein as antigens, the positively-charged particles elicit long-lasting and enhanced humoral immunity, and provide protection in S. aureus sepsis mice models. In addition, when formulated with human papillomavirus type 18 virus-like particles, it is demonstrated that particles with positive charges outperform in promoting serum antigen-specific antibody productions. This study shows that engineering AAHPs with well-controlled physicochemical properties enable the establishment of a structure-activity relationship that is critical to instruct the design of suitable engineered nanomaterial-based adjuvants within vaccine formulations for the benefits of human health.

Direct oxidation of N-ynylsulfonamides into N-sulfonyloxoacetamides with DMSO as a nucleophilic oxidant.

N-Arylethynylsulfonamides are oxidized into N-sulfonyl-2-aryloxoacetamides directly and efficiently with dimethyl sulfoxide (DMSO) as both an oxidant and solvent with microwave assistance. DFT calculations indicate that DMSO nucleophilically attacks the ethylic triple bond and transfers its oxygen atom to the triple bond to form zwitterionic anionic N-sulfonyliminiums to trigger the reaction. Then it nucleophilically attacks the generated iminium intermediates to accomplish the oxidation via the second oxygen atom transfer. The current method provides a straightforward and efficient strategy to transform various N-arylethynylsulfonamides into N-sulfonyl-2-aryloxoacetamides, sulfonyl oxoacetimides, without any other electrophilic activators or oxidants.

Methanesulfinylation of Benzyl Halides with Dimethyl Sulfoxide.

A phenyltrimethylammonium tribromide-mediated nucleophilic substitution/oxygen transformation reaction of benzyl halides with DMSO has been developed. In this transition-metal-free reaction, DMSO acts as not only a solvent but also a "S(O)Me" source, thus providing a convenient method for the efficient and direct synthesis of various benzyl methyl sulfoxides.

PEGylated doxorubicin cloaked nano-graphene oxide for dual-responsive photochemical therapy.

Graphene oxide (GO) owns huge surface area and high drug loading capacity for aromatic molecules, such as doxorubicin (DOX). However, its biocompatibility is poor and it might agglomerate in physiological conditions. Chemical modification of GO with hydrophilicpolymer, especially PEGylation, was a common method to improve its biocompatibility. But the chemical modification of GO was complicated, and its drug loading capacity might be reduced because of the occupation of its functional groups. In this study, DOX-PEG polymers with different PEG molecular weights were synthesized to modify nano graphene oxide (NGO) to simultaneously realize the solubilization of NGO and the high loading capacity of DOX. The result showed that the drug release of NGO@DOX-PEG was pH sensitive. NIR irradiation could augment the drug release, cellular uptake, cytotoxicity and nuclear translocation of nanodrugs. Among the three kinds of nanodrugs, NGO@DOX-PEG5K was superior to others. It suggested that after conjugating with PEG, the bond between DOX-PEG and NGO was weakened, which resulted in a better drug release and treatment effect. In summary, the NIR and pH dual-responsive NGO@DOX-PEG nanodrugs were developed by noncovalent modification, and it demonstrated excellent biocompatibility and photochemical therapeutic effect, presenting a promising candidate for antitumor therapy, especially NGO@DOX-PEG5K.

Cancer cell targeting, controlled drug release and intracellular fate of biomimetic membrane-encapsulated drug-loaded nano-graphene oxide nanohybrids.

Nano-graphene oxide (NGO) has been proposed as a novel drug carrier. However, the poor biocompatibility and physiological stability as well as lack of cancer targeting capability have limited its further applications in cancer therapy. To solve this problem, we developed a novel nanohybrid of NGO/DOX@SPC-FA by first allowing soy phosphatidylcholine membrane (SPC) to encapsulate DOX-loaded NGO (NGO/DOX) and then modifying the SPC membrane with PEGylated lipid-FA conjugate to achieve the display of cancer targeting FA on the nanohybrid surface. The SPC membrane (mimicking cell membrane) enabled the resultant nanohybrids (NGO/DOX@SPC-FA) to exhibit good stability and biocompatibility, high drug loading capability, efficient cellular uptake, and controlled drug release. Moreover, compared with NGO/DOX and SPC-modified NGO/DOX (NGO/DOX@SPC), the FA-modified NGO/DOX@SPC nanohybrids (NGO/DOX@SPC-FA) could deliver NGO/DOX to cancer cells with improved delivery and killing efficacy due to the presence of FA targeting motifs on the surface. The NGO/DOX@SPC-FA nanohybrids were found to be internalized specifically by FA-positive cancer cells (Hela cells) through both macropinocytosis-directed engulfment and clathrin-dependent endocytosis, and then become localized into the lysosomes. In vivo biodistribution study showed that NGO/DOX@SPC-FA had a high tumor targeting ability because of the active targeting mechanism with folate modification. In vivo antitumor therapy study demonstrated NGO/DOX@SPC-FA could significantly inhibit tumour growth and prolong the survival time of mice. Our results suggest that NGO/DOX@SPC-FA, as a novel drug delivery system with high drug loading and targeted delivery efficiency, holds promise for future cancer therapy.

Targeted delivery of in situ PCR-amplified Sleeping Beauty transposon genes to cancer cells with lipid-based nanoparticle-like protocells.

A Sleeping Beauty (SB) transposon system is made of a transposon plasmid (containing gene encoding a desired functional or therapeutic protein) and a transposase plasmid (encoding an enzyme capable of cutting and pasting the gene into the host cell genome). It is a kind of natural, nonviral gene delivery vehicle, which can achieve efficient genomic insertion, providing long-term transgenic expression. However, before the SB transposon system could play a role in promoting gene expression, it has to be delivered efficiently first across cell membrane and then into cell nuclei. Towards this end, we used a nanoparticle-like lipid-based protocell, a closed bilayer of the neutral lipids with the DNA encapsulated inside, to deliver the SB transposon system to cancer cells. The SB transposon system was amplified in situ inside the protocells by a polymerase chain reaction (PCR) process, realizing more efficient loading and delivery of the target gene. To reach a high transfection efficiency, we introduced two targeting moieties, folic acid (FA) as a cancer cell-targeting motif and Dexamethasone (DEX) as a nuclear localization signaling molecule, into the protocells. As a result, the FA enabled the modified targeting protocells to deliver the DNA into the cancer cells with an increased efficiency and the DEX promoted the DNA to translocate to cell nuclei, eventually leading to the increased chromosome insertion efficiency of the SB transposon. In vivo study strongly suggested that the transfection efficiency of FA-modified protocells in the tumor tissue was much higher than that in other tissues, which was consistent with the in vitro results. Our studies implied that with the targeting ligand modification, the protocells could be utilized as an efficient targeting gene carrier. Since the protocells were made of neutral lipids without cationic charges, the cytotoxicity of protocells was significantly lower than that of traditional cationic gene carriers such as cationic liposomes and polyethylenimine, enabling the protocells to be employed in a wider dosage range in gene therapy. Our work shows that the protocells are a promising gene carrier for future clinical applications.