Incorporation ofκ-carrageenan improves the practical features of agar/konjac glucomannan/κ-carrageenan ternary system

Three materials(agar,konjac glucomannan(KGM)andκ-carrageenan)were used to prepare ternary systems,i.e.,sol-gels and their dried composites conditioned at varied relative humidity(RH)(33%,54%and 75%).Combined methods,e.g.,scanning electron microscopy,small-angle X-ray scattering,infrared spectroscopy(IR)and X-ray diffraction(XRD),were used to disclose howκ-carrageenan addition tailors the features of agar/KGM/κ-carrageenan ternary system.As affirmed by IR and XRD,the ternary systems withκ-carrageenan below 25%(agar/KGM/carrageenan,50:25:25,m/m)displayed proper component interactions,which increased the sol-gel transition temperature and the hardness of obtained gels.For instance,the ternary composites could show hardness about 3 to 4 times higher than that for binary counterpart.These gels were dehydrated to acquire ternary composites.Compared to agar/KGM composite,the ternary composites showed fewer crystallites and nanoscale orders,and newly-formed nanoscale structures from chain assembly.Such multi-scale structures,for composites withκ-carrageenan below 25%,showed weaker changes with RH,as revealed by especially morphologic and crystalline features.Consequently,the ternary composites with lessκ-carrageenan(below 25%)exhibited stabilized elongation at break and hydrophilicity at different RHs.This hints to us that agar/KGM/κ-carrageenan composite systems can display series applications with improved features,e.g.,increased sol-gel transition point.

Simultaneous Quantification of κ-Carrageenan Oligosaccharides of DP 3, 5 and 7 by LC-MS/MS: Application to an in vitro Absorption Study

Carrageenans are widely utilized in many commercial applications such as the food and pharmaceutical industry, due to their excellent functional properties. In this study, a sensitive LC-MS/MS method was developed to determine κ-3, κ-5, and κ-7 carrageenan oligosaccharides simultaneously. Optimum MRM transitions for κ-3, κ-5, and κ-7 carrageenan oligosaccharides were(645.079→565.111, [M-H]-),(515.137→474.946, [M-2H]^2-), and(471.484→445, [M-3H]^3-), respectively. Chromatographic separation was performed on an Amide column coupled with a guard column operated at 60℃ under stepwise gradient elution. The linearity of the LC-MS/MS method for κ-3, κ-5, and κ-7 carrageenan oligosaccharides, evaluated over the concentration range of 0.10- 20.0 μmol L^-1, was excellent. The precisions of the method for κ-3, κ-5, and κ-7 carrageenan oligosaccharides were from 0.91% to 9.66%, and the inter-day precisions were from 0.92% to 10.5%. Validation of the LC-MS/MS method indicated that the method was precise and in line with the CFDA guidance. This method has been successfully applied to an in vitro absorption study.

Simultaneous bottom-up double-layer synergistic engineering by multifunctional natural molecules for efficient and stable SnO2-based planar perovskite solar cells

The performance and stability of perovskite solar cells(PSCs)is limited by detrimental defects,mostly distributed at the grain boundary(GB)of bulk perovskite film and interface,which induce serious carrier non-radiative recombination.Therefore,there is particularly urgent to realize simultaneous passivation of bulk defects and interfacial defects.In this work,a simple,low-cost and effective multifunctional modification strategy is developed by introducing theλ-Carrageenan(λ-C)as the interfacial layer of SnO_(2)/perovskite.The sulfate groups ofλ-C not only play a positive role in passivating the Sn4+from SnO_(2)film,resulting in high conductivity,but also effectively passivate the defects at the SnO_(2)/perovskite interface.Meanwhile,λ-C can effectively passivate the defects in the perovskite film due to the strong binding force between the high content of sulfate groups and PbI2.The synergistic effect ofλ-C simultaneously achieves interfacial defects and bulk defects passivation,better crystalline quality,suppressed charge recombination,released interfacial stress and more favorable interfacial energy level alignment.Based on the above efficient synergy,theλ-C-modified device achieves a high efficiency of 23.81%,which is~24.53%higher than the control device(19.12%).To our best knowledge,23.81%of power conversion efficiency(PCE)is the highest reported PCE value of PSCs employing green natural additives.Moreover,long-term and thermal stabilities are significantly improved after interface modification.Thus,this work provides an idea for developing multifunctional natural materials towards the attainment of the efficient and stable PSCs.

转谷氨酰胺酶、复合磷酸盐、卡拉胶、酪蛋白对鸡肉肠质硬度的影响

本文以鸡脯肉为原料,利用中心复合正交试验设计的原理,设计了4因子3水平的试验,并采用响应曲面法研究了转谷氨酰胺酶(0～0.8%)及复合磷酸盐(0～0.5%)、卡拉胶(0～0.8%)、酪蛋白(0～5%)对鸡肉肠硬度的综合影响。结果显示,TGase和酪蛋白能显著提高鸡肉肠硬度(p<0.05),而复合磷酸盐和卡拉胶则影响不显著(p>0.05)。并得出硬度预测回归方程,并优化得到最佳组合:TGase(0.8%)、复合磷酸盐(0%)、卡拉胶(0.8%)、酪蛋白(5%)条件下有最大硬度705.517g。

卡拉胶、黄原胶、海藻酸钠、瓜尔豆胶及转谷氨酰胺酶对鸡肉肠出品率和硬度的影响

本实验采用两因素析因试验设计,研究了转谷氨酰胺酶和四种亲水胶体(卡拉胶、黄原胶、海藻酸钠、瓜尔豆胶)对鸡肉肠硬度和出品率的影响。结果表明,随着浓度的增加,四种亲水胶体均可显著增加鸡肉肠的出品率(p<0.01);转谷氨酰胺酶对鸡肉肠的出品率没有显著的影响,且与各亲水胶体之间均无显著交互作用(p>0.05)。转谷氨酰胺酶可显著增加鸡肉肠的硬度(p<0.05),卡拉胶对转谷氨酰胺酶处理的鸡肉肠硬度无显著影响,而黄原胶、海藻酸钠、瓜尔豆胶则均极显著降低了鸡肉肠的硬度(p<0.01)。

к-卡拉胶和黄原胶复合凝胶及其载药抗菌性能研究

目的合成新型к-卡拉胶(к-CA)和黄原胶(XG)复合水凝胶,观测凝胶形貌、微结构和形成机制及其装载左氧氟沙星(LVFX)凝胶制剂的抗菌效果。方法利用溶胶-凝胶法合成к-CA/XG凝胶,使用扫描电子显微镜(SEM)、傅里叶红外光谱(IR)、X射线衍射(XRD)以及流变学等手段观测к-CA/XG凝胶结构、性质性能等;采用自制的牛津杯法对比测试LVFX凝胶制剂的抗菌效果。结果获得了新型к-CA和XG复合水凝胶体系以及LVFX凝胶新剂型。新型凝胶形貌表现为带状纹理为主的多形态微结构,在流变学上凝胶的应力屈服值只有25pa,表现为弱凝胶的性质;к-CA/XG凝胶的形成机制是天然多糖分子链之间依靠氢键作用通过螺旋形成纤维束带状纹理结构;试验表明,空白凝胶没有抑菌作用,LVFX凝胶制剂的杀菌效能可达到对照标准的50%。结论新型к-CA/XG复合凝胶合成,方法简便、成本低廉,同时利用该复合凝胶获得了新型抗菌药物凝胶制剂。

Preparation of κ-carra-Oligosaccharides with Microwave Assisted Acid Hydrolysis Method

A rapid method of microwave assisted acid hydrolysis was established to prepare κ-carra-oligosaccharides. The optimal hydrolysis condition was determined by an orthogonal test. The degree of polymerization （DP） of oligosaccharides was detected by high performance thin layer chromatography （HPTLC） and polyacrylamide gel electrophoresis （PAGE）. Considering the results of HPTLC and PAGE, the optimum condition of microwave assisted acid hydrolysis was determined. The concentration of κ-carrageenan was 5 mgmL-1; the reaction solution was adjusted to pH 3 with diluted hydrochloric acid; the solution was hydrolyzed under microwave irradiation at 100 ℃ for 15 min. Oligosaccharides were separated by a Superdex 30 column （2.6 cm × 90 em） using AKTA Purifier UPC100 and detected with an online refractive index detector. Each fraction was characterized by electrospray ioni- zation mass spectrometry （ESI-MS）. The data showed that odd-numbered κ-carra-oligosaccharides with DP ranging from 3 to 21 could be obtained with this method, and the structures of the oligosaccharides were consistent with those obtained by traditional mild acid hydrolysis. The new method was more convenient, efficient and environment-friendly than traditional mild acid hydrolysis. Our results provided a useful reference for the preparation of oligosaceharides from other polysaccharides.

A New κ-Carrageenase Cgk S from Marine Bacterium Shewanella sp. Kz7

A new κ-carrageenase gene cgkS was cloned from marine bacterium Shewanella sp. Kz7 by using degenerate and site-finding PCR. The gene was comprised of an open reading frame of 1224bp, encoding 407 amino acid residues, with a signal peptide of 24 residues. Based on the deduced amino acid sequence, the κ-carrageenase CgkS was classified into the Glycoside Hy- drolase family 16. The cgkS gene was expressed in Escherichia coli, and the recombinant enzyme was purified to homogeneity with a specific activity of 716.8 U mg-1 and a yield of 69%. Recombinant CgkS was most active at 45 ℃ and pH 8.0. It was stable at pH 6.0-9.0 and below 30℃. The enzyme did not require NaCl for activity, although its activity was enhanced by NaCI. CgkS degraded κ-carrageenan in an endo-fashion releasing tetrasaccharides and disaccharides as main hydrolysis products.

Optimization and evaluation of reduced graphene oxide hydrogel composite as a demulsifier for heavy crude oil-in-water emulsion

The rising production of produced water from oilfields had been proven to bring detrimental environmental effects.In this study,an efficient,recyclable,and environmental-friendly reduced graphene oxide immobilizedκ-Carrageenan hydrogel composite(κCaGO)was fabricated as an alternative sorbent for crude oil-in-water demulsification.Polyethyleneimine(PEI)was employed to form a stable hydrogel composite.The conditions for the immobilization of graphene oxide(GO)on PEI-modifiedκ-Carrageenan(κC)beads were optimized appropriately.An immobilization yield of 77%was attained at 2%PEI,2 h immobilization activation time,and pH 6.5.Moreover,the synthesizedκCaGO is capable of demulsification with an average demulsification efficiency of 70%.It was found that the demulsification efficiency increases with salinity andκCaGO dosage,and it deteriorates under alkaline condition.These phenomena can be attributed to the interfacial interactions betweenκCaGO and the emulsion.Furthermore,theκCaGO can be recycled to use for up to six cycles without significant leaching and degradation.As such,the synthesizedκCaGO could be further developed as a potential sorbent substitute for the separation of crude oil from produced water.

Capillary Zone Electrophoresis Investigation of Interactions between Granulocyte-colony Stimulating Factor and Dextran Sulfate/Carrageenan Oligosaccharide

The interactions between granulocyte-colony stimulating factor (G-CSF) and dextran sulfate / κ-carrageenan oligosaccharide were studied by capillary zone electrophoresis. Dextran sulfate could strongly interact with G-CSF and the complex was detected. The binding constant and stoichiometry were determined to be 1.2×106 (mol/L)-1 and 3:1, respectively. However, the interaction between κ-carrageenan oligosaccharide and G-CSF was not found.

Influence of soy protein isolate on the gel properties of walnut protein isolate-κ-carrageenan treated with NaCl

The demand for plant protein is increasing significantly due to the shortage of protein resources.Walnut protein,the main by-product of preparing walnut oil,has limited application in the food industry due to its poor solubility.It was found that the soy protein isolate(SPI)concentration had significant effects on the gel properties of the walnut protein isolate(WNPI)-κ-Carrageenan(KC)composite system treated with 15 mmol/L NaCl.The results showed that the gel strength of the composite system increased first and then decreased with the increased concentration of SPI from 0 to 2.5%.The best rheological properties,texture properties,water holding capacity((92.03±1.05)%),swelling ratio((2.04±0.19)%),freeze-thaw stability and thermal stability(85.53°C)of the composite gel were found at an SPI concentration of 1%.In the meantime,the secondary structure of protein had the least α-helix content of 10.17% and the highest β-sheet content of 39.64%,the fluorescence intensity and free sulfhydryl content reached the highest value.1% SPI could also act as a filler for WNPI to enhance the intermolecular forces such as hydrophobic interaction between the two substances,thus forming a stable gel network structure.This study can provide technical support for improving the gel properties of walnut protein and producing new plant protein gel products.

Biopolymer-stabilized emulsions on the basis of interactions betweenβ-lactoglobulin andι-carrageenan

ι-Carrageenan andβ-lactoglobulin(β-lg)stabilized oil-in-water(O/W)emulsions,which can be used for the oral administration of bioactive but environmentally sensitive ingredients,have been successfully prepared.The effects of protein/polysaccharide ratios,total biopolymer concentration,environmental stress(thermal processing and sonication),and pH on the complex formation betweenι-carrageenan andβ-lactoglobulin have been investigated.We found thatβ-lactoglobulin andι-carrageenan stabilized emulsions can be formed at pH values of 6.0,4.0,and 3.4.However,the microstructures of emulsions stabilized byβ-lactoglobulin andι-carrageenan was identified by optical microscopy,and it indicated that the emulsion prepared at pH 6.0 flocculated more extensively,while its hydrodynamic radius was much bigger than those prepared at pH 4.0 and 3.4.Regarding rheological properties,the emulsion of pH 6.0 showed a more solid-like behavior but with a lower viscosity than those of pH 4.0 and 3.4.The optimum concentration ranges forβ-lg andι-carrageenan to form stable emulsions at pH 4.0 and 3.4 were 0.3 wt-%-0.6 wt-%and 0.4 wt-%-0.7 wt-%,respectively.

Simple fabrication of carboxymethyl cellulose and k-carrageenan composite aerogel with efficient performance in removal of fluoroquinolone antibiotics from water

3D composite aerogels(CMC-CG)composed of carboxymethyl cellulose andκ-carrageenan were designed and fabricated using the one-pot synthesis technique.The optimized CMC-CG showed a good mechanical property and a high swelling ratio due to its superior textural properties with a proper chemically cross-linked interpenetrating network structure.CMC-CG was utilized for the removal of various fluoroquinolones(FQs)from water and exhibited high adsorption performance because of effective electrostatic attraction and hydrogen bonding interactions.Ciprofloxacin(CIP),a popular FQ,was used as the representative.The optimized CMC-CG had a theoretically maximal CIP uptake of approximately 1.271 mmol/g at the pH of 5.0.The adsorption capacity of CMC-CG was improved in the presence of some cations,Cu2+and Fe3+ions,at a low concentration through the bridging effect but was reduced at a high concentration.The investigation of adsorption mechanisms,based on the adsorption kinetics,isotherms and thermodynamic study,Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy analyses before and after adsorption,and changes in the adsorption performance of CMC-CG toward two molecular probes,further indicated that electrostatic attraction was the dominant interaction rather than hydrogen bonding in this adsorption.CMC-CG after saturated adsorption of CIP could be easily regenerated using a dilute NaCl aqueous solution and reused efficiently.Moreover,the disused aerogel could still be reused as a new adsorbent for effective adsorption of Cu2+ion.Overall,this study suggested the promising applications of this composite aerogel as an eco-friendly,cost-effective,and recyclable adsorbent for thie efficient removal of FQs from water.

Silk Fibroin and κ-Carrageenan Composite Films Containing Zinc-doped Bioactive Glass for Wound Closure

Natural biopolymers have excellent biocompatibility and biodegradability;they can be used as biomedical materials for wound healing.In this work,the Silk Fibroin(SF)andκ-carrageenan(κ-Car)composite films containing Zinc-doped Bioactive Glass(ZBG)have been fabricated for wound closure applications.The as-fabricated SF-κ-Car/ZBG composite films have excellent stretchability and foldability,which facilitates them for application as wound dressing.They also exhibit excellent hydrophilicity and water-absorption capacity,which can effectively absorb wound exudate and keep the wound sites under moist state.In addition,the composite films have a good antibacterial effect against S.aureus and E.coli in vitro,which can reduce the risk of wound infection.Their excellent cell compatibility is confirmed by the CCK-8 assay.The strong vascular proliferation and wound regeneration are found in SF-κ-Car/ZBG composite films on a mouse skin wound model.The SF-κCar/ZBG composite films can inhibit the secretion of inflammatory factors,and stimulate the production of vascular factors and collagen fibers.The results derived from the performed investigations revealed that the SF-κ-Car/ZBG composite films are a promising candidate dressing for wound healing applications.