Atomically Strained Metal Sites for Highly Efficient and Selective Photooxidation.

Strain engineering is an attractive strategy for improving the intrinsic catalytic performance of heterogeneous catalysts. Manipulating strain on the short-range atomic scale to the local structure of the catalytic sites is still challenging. Herein, we successfully achieved atomic strain modulation on ultrathin layered vanadium oxide nanoribbons by an ingenious intercalation chemistry method. When trace sodium cations were introduced between the V2O5 layers (Na+-V2O5), the V-O bonds were stretched by the atomically strained vanadium sites, redistributing the local charges. The Na+-V2O5 demonstrated excellent photooxidation performance, which was approximately 12 and 14 times higher than that of pristine V2O5 and VO2, respectively. Complementary spectroscopy analysis and theoretical calculations confirmed that the atomically strained Na+-V2O5 had a high surficial charge density, improving the activation of oxygen molecules and contributing to the excellent photocatalytic property. This work provides a new approach for the rational design of strain-equipped catalysts for selective photooxidation reactions.

Engineering detoxified pneumococcal pneumolysin derivative ΔA146PLY for self-biomineralization of calcium phosphate: Assessment of their protective efficacy in murine infection models.

Vaccine design ushered in the era of nanotechnology, as the vaccine is being developed toward particulate formulation. We have previously shown that the attenuated pneumolysin mutant (ΔA146PLY) was a safe and effective pneumococcal vaccine candidate. Here, to further optimize the formulation, we fused calcium phosphate (CaP) binding domains with ΔA146PLY so that the biocompatible CaP can mineralize with the protein automatically, allowing simple production of nanoparticle antigen during preparation. We fabricated four different nanoparticles, and then we compared the characteristics of different CaP-ΔA146PLY nanoparticles and demonstrated the influence of CaP binding domains on the size, shape and surface calcium content of the nanoparticles. It was found that these self-biomineralized CaP-ΔA146PLY nanoparticles varied in their capacity to induce BMDCs and splenocytes production of cytokines. We further demonstrated that, compared to free proteins, nanoparticle antigens induced more efficient humoral and cellular immune responses which was strong enough to protect mice from both pneumonia and sepsis infection. Also, the integration of CaP to protein has no significant impairment on body weight of animals, and subcutaneous injection of ΔA146PLY-peptides@CaP nanoparticles did not lead to permanent formation of nodules in the skin relative to Alum adjuvant formulated antigens. Together, our data sufficiently suggest that soluble ΔA146PLY vaccine candidate could be processed into nanoparticles by self-biomineralization of CaP, the immunogenicity of which could be efficiently improved by the CaP binding domains and biomineralization.

Antibacterial effects of Traditional Chinese Medicine monomers against Streptococcus pneumoniae via inhibiting pneumococcal histidine kinase (VicK).

Two-component systems (TCSs) have the potential to be an effective target of the antimicrobials, and thus received much attention in recent years. VicK/VicR is one of TCSs in Streptococcus pneumoniae (S. pneumoniae), which is essential for pneumococcal survival. We have previously obtained several Traditional Chinese Medicine monomers using a computer-based screening. In this study, either alone or in combination with penicillin, their antimicrobial activities were evaluated based on in vivo and in vitro assays. The results showed that the MICs of 5'-(Methylthio)-5'-deoxyadenosine, octanal 2, 4-dinitrophenylhydrazone, deoxyshikonin, kavahin, and dodecyl gallate against S. pneumoniae were 37.1, 38.5, 17, 68.5, and 21 µg/mL, respectively. Time-killing assays showed that these compounds elicited bactericidal effects against S. pneumoniae D39 strain, which led to a 6-log reduction in CFU after exposure to compounds at four times of the MIC for 24 h. The five compounds inhibited the growth of Streptococcus pyogenes, Streptococcus mitis, Streptococcus mutans or Streptococcus pseudopneumoniae, meanwhile, deoxyshikonin and dodecyl gallate displayed strong inhibitory activities against Staphylococcus aureus. These compounds showed no obvious cytotoxicity effects on Vero cells. Survival time of the mice infected by S. pneumoniae strains was prolonged by the treatment with the compounds. Importantly, all of the five compounds exerted antimicrobial effects against multidrug-resistant clinical strains of S. pneumoniae. Moreover, even at sub-MIC concentration, they inhibited cell division and biofilm formation. The five compounds all have enhancement effect on penicillin. Deoxyshikonin and dodecyl gallate showed significantly synergic antimicrobial activity with penicillin in vivo and in vitro, and effectively reduced nasopharyngeal and lung colonization caused by different penicillin-resistant pneumococcal serotypes. In addition, the two compounds also showed synergic antimicrobial activity with erythromycin and tetracycline. Taken together, our results suggest that these novel VicK inhibitors may be promising compounds against the pneumococcus, including penicillin-resistant strains.

In vitro maturation and artificial activation of donkey oocytes.

Three media were evaluated for their ability to support in vitro maturation of donkey (Equus asinus) oocytes and their development after parthenogenetic activation. The basal medium for Medium 1 (M1) and Medium 2 (M2) was M199 and DMEM/F12 respectively, whereas, Medium 3 (M3) consisted of equal parts (v/v) of M199 and DMEM/F12. All three media were supplemented with 10% (v/v) fetal calf serum, 0.01 units/mL porcine FSH, 0.01 units/mL equine LH, 200 ng/mL insulin-like growth factor 1(IGF-I), 10 µl/mL insulin-transferrin-selenium (ITS), 0.1 mg/mL taurine, 0.1 mg/mL L-cysteine, 0.05 mg/mL L-glutamine, 0.11 mg/mL sodium pyruvate, and 25 mg/mL gentamycin. There were no significant differences among the three maturation media for oocyte maturation. Maturation rate of donkey oocytes in M1 was 53% for compact (Cp) cumulus-oocyte complexes and 75% for expanded (Ex) cumulus-oocyte complexes; in M2 these were 55 and 77%, respectively; and in M3, 58 and 75%. The percentage of cleaved parthenotes and 4- or 8-cell embryos were not significantly different for oocytes matured in the various media (61 and 24% for M1; 66 and 32% for M2; and 67 and 33% for M3). Oocytes matured in M3 tended to yield a higher rate of advanced embryo development (morula) than oocytes matured in M1 (22 vs 9%; P = 0.07). In conclusion, donkey oocytes were matured and parthenogenetically activated in vitro, using methods similar to those used in the horse.