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.

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.

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.

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.

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.

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.