Single-Molecule Spectroscopy Reveals the Plasmon-Assisted Nanozyme Catalysis on AuNR@TiO2.

Gold nanoparticles are frequently employed as nanozyme materials due to their capacity to catalyze various enzymatic reactions. Given their plasmonic nature, gold nanoparticles have also found extensive utility in chemical and photochemical catalysis owing to their ability to generate excitons upon exposure to light. However, their potential for plasmon-assisted catalytic enhancement as nanozymes has remained largely unexplored due to the inherent challenge of rapid charge recombination. In this study, we have developed a strategy involving the encapsulation of gold nanorods (AuNRs) within a titanium dioxide (TiO2) shell to facilitate the efficient separation of hot electron/hole pairs, thereby enhancing nanozyme reactivity. Our investigations have revealed a remarkable 10-fold enhancement in reactivity when subjected to 530 nm light excitation following the introduction of a TiO2 shell. Leveraging single-molecule kinetic analyses, we discovered that the presence of the TiO2 shell not only amplifies catalytic reactivity by prolonging charge relaxation times but also engenders additional reactive sites within the nanozyme's intricate structure. We anticipate that further enhancements in nanozyme performance can be achieved by optimizing interfacial interactions between plasmonic metals and semiconductors.

Efficacy of novel recombinant fowlpox vaccine against recent Mexican H7N3 highly pathogenic avian influenza virus.

Since 2012, H7N3 highly pathogenic avian influenza (HPAI) has produced negative economic and animal welfare impacts on poultry in central Mexico. In the present study, chickens were vaccinated with two different recombinant fowlpox virus vaccines (rFPV-H7/3002 with 2015 H7 hemagglutinin [HA] gene insert, and rFPV-H7/2155 with 2002 H7 HA gene insert), and were then challenged three weeks later with H7N3 HPAI virus (A/chicken/Jalisco/CPA-37905/2015). The rFPV-H7/3002 vaccine conferred 100% protection against mortality and morbidity, and significantly reduced virus shed titers from the respiratory and gastrointestinal tracts. In contrast, 100% of sham and rFPV-H7/2155 vaccinated birds shed virus at higher titers and died within 4 days. Pre- (15/20) and post- (20/20) challenge serum of birds vaccinated with rFPV-H7/3002 had antibodies detectable by hemagglutination inhibition (HI) assay using challenge virus antigen. However, only a few birds (3/20) in the rFPV-H7/2155 vaccinated group had antibodies that reacted against the challenge strain but all birds had antibodies that reacted against the homologous vaccine antigen (A/turkey/Virginia/SEP-66/2002) (20/20). One possible explanation for differences in vaccines efficacy is the antigenic drift between circulating viruses and vaccines. Molecular analysis demonstrated that the Mexican H7N3 strains have continued to rapidly evolve since 2012. In addition, we identified in silico three potential new N-glycosylation sites on the globular head of the H7 HA of A/chicken/Jalisco/CPA-37905/2015 challenge virus, which were absent in 2012 H7N3 outbreak virus. Our results suggested that mutations in the HA antigenic sites including increased glycosylation sites, accumulated in the new circulating Mexican H7 HPAIV strains, altered the recognition of neutralizing antibodies from the older vaccine strain rFPV-H7/2155. Therefore, the protective efficacy of novel rFPV-H7/3002 against recent outbreak Mexican H7N3 HPAIV confirms the importance of frequent updating of vaccines seed strains for long-term effective control of H7 HPAI virus.