Robust Waterborne Polyurethane/Wool Keratin/Silk Sericin Freeze-Drying Composite Membrane for Heavy Metal Ions Adsorption

Wool keratin(WK)and silk sericin(SS)have the ability to interact with metal ions.In order to take advantage of this potential,a novel environmentally friendly waterborne polyurethane(WPU)/WK/SS membrane named as WPU&WK&SS membrane with crosslinked structure was constructed by freeze-drying via self-assembly style.Surface morphology and chemical structure characterization were investigated by scanning electron microscopy(SEM)and Fourier transform infrared spectroscopy(FT-IR).In addition,the adsorption experiments of Cu2+and Cr6+were performed to evaluate the adsorption of WPU&WK&SS membrane,including adsorption kinetics,adsorption isotherm models and various factors affecting adsorption.Further investigation indicates that the maximum adsorption capacity of Cu2+and Cr6+can reach 54.21 mg·g-1and 85.21 mg·g-1,respectively,which are higher than most of the reported adsorbents.Through adsorption kinetics and thermodynamic analysis,it is find that the pseudo-second-order kinetic equation and the Langmuir adsorption isotherm model are more suitable for the static adsorption of Cu2+and Cr6+by WPU&WK&SS membrane.

Cell Growth and Desorption on the Surface of Temperature-sensitive Semi-IPNs Hydrogels Based on Silk Sericin

Semi-interpenetrating （semi-IPNs） hydrogels containing biocompatible silk sericin （SS） and poly（N-isopropylacrylamide）（PNIPAM） were prepared as novel cellular matrices. Their maximum swelling degree and basic characteristics for biomedical applications such as mouse ？broblasts （L929） cell proliferation and desorption were investigated. The results showed that the incorporation of high hydrophilic SS into PNIPAM hydrogel increased the maximum swelling degree of the semi-IPNs hydrogels, and the adhesion and growth of the L929 on semi-IPNs hydrogels were at least comparable to, or even better than, that on conventional PNIPAM hydrogel. In addition, L929 cells were found to detach from the hydrogels surface naturally by controlling environmental temperature. These results suggest great potential of semi-IPNs hydrogels in tissue engineering.

Temperature-pH Sensitive IPN Hydrogels Composed of Silk Sericin and Poly(N-isopropylacrylamide)

Interpenetrating polymer network （IPN） composed of silk sericin （SS） and poly（N-isopropylacrylamide） （PNIPAAm） was prepared. The morphology of the IPNs, in which the SS phase was stained with ammonium cuprate, was examined with TEM and a relative homogeneous distribution of the two polymers was exhibited. The swelling behavior of the IPN hydrogels showed both temperature and pH dependences.

Selective Adsorption of Ag(I) from Electronic Waste Leachate Using Modified Silk Sericin

A novel biosorbent was synthesized by grafting bisthiourea(BTU)on a silk sericin(SS)matrix.This biosorbent was denoted as BTU-SS and characterized by Fourier transform infrared spectroscopy(FTIR),zeta potential measurements,elemental analysis,and X-ray photoelectron spectroscopy(XPS).As revealed by the adsorption experiments,both BTU-SS and SS showed low affinity towards coexisting base metallic ions in Ag(I)-Cu(II)-Zn(II)-Ni(II)-Pb(II)electronic waste leachate mixtures,while their adsorption capacities towards Ag(I)reached 30.5 and 10.4 mg∙g-1 at a pH of 5.0,respectively.BTU-SS showed higher selectivity towards Ag(I)than SS,as revealed by the Ag(I)partition coefficients between the biosorbents and the leachate(16634.6 and 403.3,respectively).As further demonstrated by column experiments,BTU-SS allowed the separation of Ag(I)from an electronic waste leachate.Thermodynamic studies showed that the adsorption of Ag(I)was exothermic and spontaneous,while adsorption kinetic experiments revealed that chemisorption dominated the adsorption process with activation energies of 47.67 and 53.27 kJ∙mol-1 for BTU-SS and SS,respectively.FTIR and XPS analyses of fresh and Ag(I)-loaded BTU-SS further revealed an adsorption mechanism mainly involving electrostatic and coordination interactions.

Injectable silk sericin scaffolds with programmable shape-memory property and neuro-differentiation-promoting activity for individualized brain repair of severe ischemic stroke

Severe ischemic stroke damages neuronal tissue,forming irregular-shaped stroke cavities devoid of supporting structure.Implanting biomaterials to provide structural and functional support is thought to favor ingrowth of regenerated neuronal networks.Injectable hydrogels capable of in situ gelation are often utilized for stroke repair,but challenged by incomplete gelation and imprecise control over end-macrostructure.Injectable shape-memory scaffolds might overcome these limitations,but are not explored for stroke repair.Here,we report an injectable,photoluminescent,carbon-nanotubes-doped sericin scaffold(CNTs-SS)with programmable shape-memory property.By adjusting CNTs’concentrations,CNTs-SS′recovery dynamics can be mathematically calculated at the scale of seconds,and its shapes can be pre-designed to precisely match any irregular-shaped cavities.Using a preclinical stroke model,we show that CNTs-SS with the customized shape is successfully injected into the cavity and recovers its pre-designed shape to well fit the cavity.Notably,CNTs-SS’near-infrared photoluminescence enables non-invasive,real-time tracking after in vivo implantation.Moreover,as a cell carrier,CNTs-SS not only deliver bone marrow mesenchymal stem cells(BMSCs)into brain tissues,but also functionally promote their neuronal differentiation.Together,we for the first time demonstrate the feasibility of applying injectable shape-memory scaffolds for stroke repair,paving the way for personalized stroke repair.

Effect of silk sericin on morphology and structure of calcium carbonate crystal

In this paper, silk sericin was employed to regulate the mineralization of calcium carbonate （CaC03）. CaCO3 composite particles were prepared by the precipita- tion reaction of sodium carbonate with calcium chloride solution in the presence of silk sericin. The as-prepared samples were collected at different reaction time to study the crystallization process of CaCO3 by scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （FTIR）, thermogravimetric analysis （TGA） and X-ray diffraction （XRD）. The results showed that silk sericin significantly affected the morphology and crystallographic polymorph of CaCO3. With increasing the reaction time, the crystal phase of CaCO3 transferred from calcite dominated to vaterite dominated mixtures, while the morphology of CaCO3 changed from disk-like calcite crystal to spherical vaterite crystal. These studies showed the potential of silk sericin used as a template molecule to control the growth of inorganic crystal.

Co-encapsulation efficiency of silk sericin-alginate-prebiotics and the effectiveness of silk sericin coating layer on the survival of probiotic Lactobacillus casei

The use of silk sericin protein as a biomaterial to co-encapsulate probiotic Lactobacillus casei TISTR 1463 with alginate and various prebiotics was determined.In addition,0.2%silk sericin was also evaluated as a coating material to improve the viability of probiotic cells.Silk sericin coating has the potential to enhance probiotic survival in freeze-dried microcapsules.Under refrigerated storage condition of 4℃for 120 days,alginate-silk sericin-maltitol with silk sericin coating(ASM-C)provided the best performance with the lowest inactivation rate(k)and the highestδparameter(the first decimal reduction time)applied by the log-linear and Weibull models,respectively.However,the stability was relatively low at the temperature of 30℃.Co-encapsulation of alginate-silk sericin-prebiotic and coated with silk sericin exerted a protective impact on the strain survival when exposed to high temperatures and transited through the digestive system.