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Despite considerable progress having been made in thermosensitive protein hydrogels, regulating their thermal transitions remains a challenge due to the intricate molecular structures and interactions of the underlying protein polymers. Here we report a genetic fusion strategy to tune the unique dual thermal transitions of the C-terminal domain (CTD) of spider major ampullate spidroin 1, and explore the regulation mechanism by biophysical characterization and molecular dynamics simulations. We found that the fusion of elastin-like polypeptides (ELPs) tuned the dual transition temperatures of CTD to a physiologically relevant window, by introducing extra hydrogen bonding at low temperatures and hydrophobic interactions at high temperatures. The resulting hydrogels constructed from the fusion proteins were demonstrated to be a promising vehicle for cell preservation and delivery. This study provides insights on the regulation of the dual thermosensitive protein hydrogels and suggests a potential application of the hydrogels for consolidated cell storage and delivery.

Enhancing cross-protections against diverse influenza viruses is desired for influenza vaccinations. Neuraminidase (NA)-specific antibody responses have been found to independently correlate with a broader influenza protection spectrum. Here, we report a sequential immunization regimen that includes priming with NA protein followed by boosting with peptide nanoclusters, with which targeted enhancement of antibody responses in BALB/c mice to certain cross-protective B-cell epitopes of NA was achieved. The nanoclusters were fabricated via desolvation with absolute ethanol and were only composed of composite peptides. Unlike KLH conjugates, peptide nanoclusters would not induce influenza-unrelated immunity. We found that the incorporation of a hemagglutinin peptide of H2-d class II restriction into the composite peptides could be beneficial in enhancing the NA peptide-specific antibody response. Of note, boosters with N2 peptide nanoclusters induced stronger serum cross-reactivities to heterologous N2 and even heterosubtypic N7 and N9 than triple immunizations with the prototype recombinant tetrameric (rt) N2. The mouse challenge experiments with HK68 H3N2 also demonstrated the strong effectiveness of the peptide nanocluster boosters in conferring heterologous protection. [ABSTRACT FROM AUTHOR]