Yeast-induced Multistage Pore Sericin/genipin/calcium Alginate Hydrogel And Its Adsorption Behavior

In comparison with conventional hydrogels,superporous hydrogels possess both high swelling kinetics and high swelling degree,improved response-rate of gels at the same time.Pore architecture in the hydrogel matrix can be formed via the addition of porogen templates during gelation.Porogens are usually used for creating porous structure in hydrogels,e.g.supercritical CO₂,surfactants,silica particles and bicarbonate etc.,while they are limited due to complex operation,complicated post-processing,high cost or residued chemicals etc.Yeast is a facultative anaerobe,which can produce CO₂ by aerobic and anaerobic respiration.This shows yeast was a good foaming agent for the advantages such as high breed speed,rich raw material,low cost,good safety and environmental friendliness.In this work,learning from the pore formation mechanism of bread and steamed bread and combineing yeast fermentation and ionic cross-linking,a microorganism inspired porous hydrogel membrane?MIHM?was prepared.The effects of yeast/SA content on the appearance,cross-linking mechanism,pore shape,porosity,hydrophilicity/hydrophobicity,swelling behavior and adsorption performance for removing crystal violet?CV?of obtained hydrogel membranes were systematically studied.It turned out that:the MIHM hydrogel membranes exhibited low transparency and hierarchical porous structure with pore sizes varying from 2 nm to 1 mm leading to CA values increasing from 63.65° to 107.83° and equilibrium swelling ratios decreasing from 79.72 to 18.05.The results upon adsorption kinetics of CV exhibited an encouraging uptake capacity of 18,40 mg/g at 10 mg/g and the adsorption kinetics of CV could be well defined by pseudo-first-order kinetic equation because of the electrostatic adsorption.Then,taking advantage of fermentation process in microbiology and excellent biocompatibility of sericin,a novel super-porous double network IPN hydrogel based on genipin cross-linked silk sericin and calcium cross-linked sodium alginate was prepared.The effects of only silk sericin or both silk sericin and genipin on the appearance,pore shape,porosity,hydrophilicity/hydrophobicity,swelling behavior,thermo stability and mechanical property of obtained hydrogel membranes were systematically studied.The cross-linking mechanism of silk sericin and genipin was confirmed and the double network cross-linking mechanism was described.The adsorption kinetics of crystal violet of the MIDHO,MIDH-S and MIDH-S/G were analyzed and the adsorption mechanism was described.It proved that the obtained hydrogel exhibited lower transparency and obvious super-porous structure.Due to hydrophilicity of genipin/SS,compared to calcium alginate hydrogel,the maximum equilibrium swelling ratios increased to 88.53 from 43.81,while the contact angel values decreased from 81.40° to 60.67°.DMA results revealed that the increased cross-linking network of genipin/SS increased storage modulus of porous calcium alginate hydrogel.The adsorption kinetics of crystal violet could be well defined by pseudo-first-order kinetic equation with a high correlation coefficient.