Search

Stimuli-responsivehydrogels have great potentials in biomedicaland biotechnological applications. Due to the advantages of precisecontrol over molecular weight and being biodegradable, protein-basedhydrogels and their applications have been extensively studied. However,protein hydrogels with dual thermosensitive properties are rarelyreported. Here we present the first report of dual thermosensitivehydrogels assembled from the conserved C-terminal domain of spiderdragline silk. First, we found that recombinant C-terminal domainof major ampullate spidroin 1 (MaSp1) of the spider Nephila clavipesformed hydrogels when cooled toapproximately 2 °C or heated to 65 °C. The conformationalchanges and self-assembly of the recombinant protein were studiedto understand the mechanism of the gelation processes using multiplemethods. It was proposed that the gelation in the low-temperatureregime was dominated by hydrogen bonding and hydrophobic interactionbetween folded protein molecules, whereas the gelation in the high-temperatureregime was due to cross-linking of the exposed hydrophobic patchesresulting from partial unfolding of the protein upon heating. Moreinterestingly, genetic fusion of the C-terminal domain to a shortrepetitive region of N. clavipesMaSp1resulted in a chimeric protein that formed a hydrogel with significantlyimproved mechanical properties at low temperatures between 2 and 10°C. Furthermore, the formation of similar hydrogels was observedfor the recombinant C-terminal domains of dragline silk of differentspider species, thus demonstrating the conserved ability to form dualthermosensitive hydrogels. These findings may be useful in the designand construction of novel protein hydrogels with tunable multiplethermosensitivity for applications in the future. [ABSTRACT FROM AUTHOR]

The currently used hemoperfusion adsorbents such as activated carbon and ion-exchange resin show dissatisfactory hemocompatibility, and a large dose of injected heparin leads to the increasing cost and the risk of systematic bleeding. Natural polysaccharide adsorbents commonly have good biocompatibility, but their application is restricted by the poor mechanical strength and low content of functional groups. Herein, we developed an efficient, self-anticoagulant and blood compatible hemoperfusion adsorbent by imitating the structure and functional groups of heparin. Carrageenan and poly(acrylic acid) (PAA) cross-linked networks were built up by the combination of phase inversion of carrageenan and post-cross-linking of AA, and the formed dual-network structure endowed the beads with improved mechanical properties and controlled swelling ratios. The beads exhibited low protein adsorption amounts, low hemolysis ratios, low cytotoxicity, and suppressed complement activation and contact activation levels. Especially, the activated partial thromboplastin time, prothrombin time, and thrombin time of the gel beads were prolonged over 13, 18, and 4 times than those of the control. The self-anticoagulant and biocompatible beads showed good adsorption capacities toward exogenous toxins (560.34 mg/g for heavy metal ions) and endogenous toxins (14.83 mg/g for creatinine, 228.16 mg/g for bilirubin, and 18.15 mg/g for low density lipoprotein (LDL)), thus, highlighting their potential usage for safe and efficient blood purification. [ABSTRACT FROM AUTHOR]