Analysis of Compression Resistance and Oil Adsorption Capacity of Cellulose/NaOH Cryogels

This work aimed at analyzing the petroleum adsorption capacity and the compressive strength of cellulose cryogels produced with the addition of 4 and 8%(w/w)sodium hydroxide(NaOH).Cryogels were produced from a 1.5%(m/m)suspension of cellulose microfibers,which originated from Pinus elliotti,in distilled water.The addition of NaOH increased the compression strength of cryogel by 30% when compared to cryogel without the reagent.Due to the 50% decrease in volume,the cryogel FLNB-8h(8%NaOH)has its petroleum adsorption capacity decreased in average by 58%,whereas the FLNB-4(4%NaOH)cryogel had it only by 14%.The cellulose suspension which provided the best results for the properties of the cryogels tested had a 4%concentration of NaOH.

Ice-and cryogel-soil composites in water-retaining elements in embankment dams constructed in cold regions

There are a number of serious problems connected with building and repairing water-reining elements in embankment dams in cold regions. One of them is the difficulty in finding inexpensive clay materials with the necessary structural properties and using them in the winter. Another is the cracks that appear in the upper part of a dam when the core freezes to the banks, and leakage along the cracks threatens to desWoy the dam. Still another is the process of erosion at the bottom of the core which may occur through fissures in the rock foundation of a dam and in transport constructions. Also, the behaviour of water-retaining elements during eazthquakes is unreliable. All of these problems can be solved by using iceand cryogel-soil composites created by cryotropic gel formation （CGF）. Our laboratory investigations demonstrate that the materials proposed for water-retaining elements have the necessary permeable, plastic, thermophysical, and slrength properties to solve all of these problems. Certain consmactious of water-retaining elements which may prove to be both safe and cost-effective are proposed. However, these iceand cryogel-soil composites need to be field-validated before they are used in dams and transport structures in cold regions.

Preparation of Supermacroporous Composite Cryogel Embedded with SiO_2 Nanoparticles

与 SiO2 nanoparticles 嵌入的 Supermacroporous 合成 cryogels 被 acrylamide (AAm ) 和 N 的反应单体混合的激进的低温实验法的 copolymerization 准备，在玻璃列在结冰温度变化条件下面包含 SiO2 nanoparticles (到从 0.01 ～ 0.08 的单体 AAm 的 nanoparticles 的集体比率) 的 N-methylene-bis-acrylamide (MBAAm ) 。这些合成 cryogels 的性质被测量。到以不同液体流动率的 cryogel 床的理论板(HETP ) 的高度等价物被住处时间分发(RTD ) 用 tracer 脉搏反应方法决定。与 0.02 的 SiO2 nanoparticles 的集体部分嵌入的合成 cryogel 矩阵介绍了最好的性质并且在下列接枝聚合被采用。在有 2-acrylamido-2-methyl-1-propanesulfonic 酸(AMPSA ) 的合成 cryogel grafted 的溶解酵素的色析法的过程被执行评估蛋白质突破和 elution 特征。层析能在相对高的表面的速度被执行，即， 15 厘米 ? ‥髧躘? 用 ? 用吗？？

Relaxation of Mechanical Stress in Poly(vinyl alcohol) Cryogels of Different Compositions

The study presents the experimental results of measurements of the relaxation time of cryogels formed from various colloid-dispersed systems based on a poly(vinyl alcohol) aqueous solution.It is shown that the value of relaxation time,which characterizes the relationship between the viscosity and elasticity of real bodies,describes the rheological properties of materials more objectively than the traditional assessment of their physical and mechanical characteristics only by the elasticity modulus of the samples.

A Macroporous Cryogel with Enhanced Mechanical Properties for Osteochondral Regeneration In vivo

The dense networks of conventional hydrogel hinder the efficient cell penetration and thus tissue regeneration.In this study,a macroporous cryogel with excellent mechanical properties was designed and fabricated through cryogelation and crosslinking of methacrylated gelatin(Gel-MA)and gelatin grafted with 2-ureido-4[1H]-6-methyl-pyrimidinone(Gel-UPY).The successful modification of the two functional units on the side chain of gelatin was confirmed by ^(1)H-NMR and infrared spectroscopy.The macroporous structure of cryogel was verified by scanning electron microscopy and confocal microscopy.The compressive modulus of cryogel(110 kPa)was 2 magnitudes higher than that of the conventional hydrogel of the same chemical compositions(8 kPa).Both the hydrogel and cryogel exhibited excellent stress-recovery ability.The cryogel could well maintain the viability of chondrocytes and facilitated their migration into the scaffold interior.After being implanted into osteochondral defects in rabbits for 12 w,the Gel-MA/Gel-UPY cryogel better facilitated the regeneration of upper cartilage and subchondral bone compared to the conventional hydrogel.

Hypoxia-inducing cryogels uncover key cancer-immune cell interactions in an oxygen-deficient tumor microenvironment

Hypoxia is a major factor shaping the immune landscape,and several cancer models have been developed to emulate hypoxic tumors.However,to date,they still have several limitations,such as the lack of reproducibility,inadequate biophysical cues,limited immune cell infiltration,and poor oxygen(O_(2))control,leading to non-pathophysiological tumor responses.Therefore,it is essential to develop better cancer models that mimic key features of the tumor extracellular matrix and recreate tumor-associated hypoxia while allowing cell infiltration and cancer-immune cell interactions.Herein,hypoxia-inducing cryogels(HICs)have been engineered using hyaluronic acid(HA)to fabricate three-dimensional microtissues and model a hypoxic tumor microenvironment.Specifically,tumor cell-laden HICs have been designed to deplete O_(2) locally and induce long-standing hypoxia.HICs promoted changes in hypoxia-responsive gene expression and phenotype,a metabolic adaptation to anaerobic glycolysis,and chemotherapy resistance.Additionally,HIC-supported tumor models induced dendritic cell(DC)inhibition,revealing a phenotypic change in the plasmacytoid DC(pDC)subset and an impaired conventional DC(cDC)response in hypoxia.Lastly,our HIC-based melanoma model induced CD8^(+)T cell inhibition,a condition associated with the downregulation of pro-inflammatory cytokine secretion,increased expression of immunomodulatory factors,and decreased degranulation and cytotoxic capacity of T cells.Overall,these data suggest that HICs can be used as a tool to model solid-like tumor microenvironments and has great potential to deepen our understanding of cancer-immune cell relationship in low O_(2) conditions and may pave the way for developing more effective therapies.

Ion imprinted cryogel-based supermacroporous traps for selective separation of cerium(Ⅲ) in real samples

This study demonstrates the preparation and characterization of a novel ion imprinted cryogel which exhibits high affinity and selectivity towards Ce（Ⅲ） ions in aqueous solutions and bastnasite ore samples.2-Hydroxyethyl methacrylate（HEMA） and N-methacryloylamido antipyrine（MAAP） were used as functional monomers for the preparation of Ce（Ⅲ） imprinted cryogel. The effects of various factors such as initial Ce（Ⅲ） concentration, flow rate, pH, interaction time and ionic strength on the Ce（Ⅲ） binding to the prepared ion imprinted cryogels were also studied. The binding equilibrium for Ce（Ⅲ） is obtained in30 min at the flow rate of 0.5 mL/min. The maximum binding capacity of the prepared ion imprinted cryogel towards Ce（Ⅲ） is obtained as 36.58 mg/g at optimum conditions. The selectivity of the prepared ion imprinted cryogel towards Ce（Ⅲ） in the presence of other possible interfering lanthanide ions such as La（Ⅲ） and Nd（Ⅲ） were also performed. The obtained results showed that the prepared ion imprinted cryogel exhibits high selectivity and sensitivity towards Ce（Ⅲ） ions. The limit of detection（LOD） was found as 50 μg/L.

半疏水晶胶微球的悬浮特性及固载乳杆菌合成有机酸

针对有机酸生物合成过程中底物和产物抑制、细胞密度低和耐受性弱等问题,采用“结晶致孔-低温聚合”方法制备聚甲基丙烯酸羟乙酯-甲基丙烯酸丁酯半疏水晶胶微球,通过高速成像和数值模拟研究10 L搅拌式生物反应器(STR)内的悬浮行为,通过固载乳杆菌分析半疏水晶胶微球在乳酸和苯乳酸生物合成中的作用。结果表明,数值模拟得到晶胶微球的悬浮特性与高速成像实验结果基本一致,体积分数为3%的晶胶微球均匀悬浮所需最低搅拌转速为55 r·min-1;在晶胶固载乳杆菌发酵联产乳酸和苯乳酸过程中,乳杆菌生物量达10.5 g·L^(-1),相比于无载体发酵提高了84.2%;在第1次补料期间,乳酸的发酵周期大幅缩短至21 h,比无载体发酵周期缩短了50%。

Study of locust bean gum reinforced cyst-chitosan and oxidized dextran based semi-IPN cryogel dressing for hemostatic application

Severe blood loss due to traumatic injuries remains one of the leading causes of death in emergency settings.Chitosan continues to be the candidate material for hemostatic applications due to its inherent hemostatic properties.However,available chitosan-based dressings have been reported to have an acidic odor at the wound site due to the incorporation of acid based solvents for their fabrication and deformation under compression owing to low mechanical strength limiting its usability.In the present study semi-IPN cryogel was fabricated via Schiff's base cross-linking between the polyaldehyde groups of oxidized dextran and thiolated chitosan in presence of locust bean gum(LBG)known for its hydrophilicity.Polymerization at
12C yielded macroporous semi-IPN cryogels with an average pore size of 124.57±20.31 mm and 85.46%porosity.The hydrophobicity index of LBG reinforced semi-IPN cryogel was reduced 2.42 times whereas the swelling ratio was increased by 156.08%compare to control cryogel.The increased hydrophilicity and swelling ratio inflated the compressive modulus from 28.1 kPa to 33.85 for LBG reinforced semi-IPN cryogel.The structural stability and constant degradation medium pH were also recorded over a period of 12 weeks.The cryogels demonstrated lower adsorption affinity towards BSA.The cytotoxicity assays(direct,indirect)with 3T3-L1 fibroblast cells confirmed the cytocompatibility of the cryogels.The hemolysis assay showed<5%hemolysis confirming blood compatibility of the fabricated cryogel,while whole blood clotting and platelet adhesion assays confirmed the hemostatic potential of semi-IPN cryogel.

A robust polyacrylic acid/chitosan cryogel for rapid hemostasis

Currently,it is a challenge to develop hemostatic materials with high water absorption capacity and anti-fatigue properties for quickly preventing massive hemorrhage from arteries and visceral organs.A series of polyacrylic acid/chitosan(PAA/CS)cryogels were prepared by a cryostructurization technique to improve mechanical performance and hemostatic efficiency of chitosan(CS).In this system,the chemically cross-linked PAA network was used as a framework to improve water absorption behaviors and mechanical strength.The CS network was co-blended by hydrogen bonding and electrostatic interactions,both of which synergistically promoted hemostasis.These cryogels had high porosity(>94%),rapid water absorption rate(<3 s),high blood absorption capacity(>2000%),outstanding mechanical strength,and fatigue resistance.Moreover,the results of cytotoxicity and hemolysis demonstrated that the cryogels had good biocompatibility.Notably,the PAA/CS cryogels exhibited superior whole blood coagulation ability and red blood cell and platelet adhesion ability compared to those of commercial hemostatic dressing(gauze,gelatin sponges,and CS sponges).Based on these results,mouse femoral artery hemorrhage models and liver hemorrhage models were prepared to investigate the hemostatic ability of the prepared PAA/CS cryogels.Results suggested that the hemostatic ability of PAA5/CS cryogels was superior to that of commercial hemostatic materials.Therefore,the PAA/CS cryogels showed potential application in preventing massive hemorrhage from arteries and visceral organs.

Porous photothermal antibacterial antioxidant dual–crosslinked cryogel based on hyaluronic acid/polydopamine for non-compressible hemostasis and infectious wound repair

Cryogel dressings with good absorption ability and photothermal antibacterial properties for preventing wound infections and treating infected wounds have attracted widespread attention.In this work,a series of cryogels with macroporous structure,antioxidant and photothermal properties were prepared based on adipic dihydrazide modified hyaluronic acid(HA-ADH),and dopamine(DA).The antioxidant properties,hemostatic properties,near infrared(NIR)assisted photothermal antibacterial ability provided by polydopamine,recyclable compression mechanical properties,and cytocompatibility were tested.The results demonstrated that the HA-ADH/DA cryogels have stable mechanical properties,great antibacterial properties against E.coli(EC)and methicillin-resistant S.aureus(MRSA).The high swelling ratio due to the high water retention of HA equipped the cryogels with the capability of absorbing exuded blood and excessive tissue fluid in the infected full-thickness skin defect model of mouse.The cryogels demonstrated good cytocompatibility and antioxidant performance through cell tests and 1,1-diphenyl-2-methylbenzohydrazino(DPPH)scavenging efficiency test.The cryogels showed enhanced blood-clotting index(BCI)and better hemostatic ability in the mouse liver trauma model and the rat deep noncompressible liver defect model compared with gauze and gelatin sponge.Furthermore,compared with commercial TegadermTMdressing in vivo,the HA-ADH/DA cryogels could greatly promote infected skin wound healing in a full-thickness infected skin defect wound model.In summary,the macroporous HAADH/DA cryogels with good antioxidant,high swelling ratio,photothermal antibacterial property,and biocompatibility are a promising hemostatic material and wound healing dressing.

Transpiration-prompted Photocatalytic Degradation of Dye Pollutant with AuNPs/PANI Based Cryogels

Incautious discharge of organic dyes such as methyl orange(MO)has produced serious pollution to the environment,calling for the efficient techniques to remove them with retaining the green world.The photo-catalytic degradation of organic dyes is promising among the developed techniques.Thus,a strategy based on transpiration-prompted photocatalytic degradation of dye pollutant under sunlight is put forward.Aniline(ANI)is graft-polymerized onto poly(acrylamide-co-N-4-aminophenylacrylamide)(PAAm)cryogel embedded with gold nanoparticles(AuNPs,diameter:4-10 nm).The obtained cryogels integrated with AuNPs and PANI inside PAAm matrix(AuNP@PAAm-g-PANI)have been structurally explored based on the chemical composition and the phase/porous morphology.SEM and TEM observation shows that PANI and AuNPs are uniformly distributed in PAAm matrix.Since the macro-porosity of cryogel,hydrophilicity of PAAm and photo-thermal activity of PANI,PAAm-g-PANI cryogels without AuNPs can have a photo-thermal evaporation rate of water at 1.63 kg·m^(-2)·h^(-1).As a comparison,Au NP@PAAm-g-PANI cryogels with AuNPs exhibit higher one at 2.20 kg·m^(-2)·h^(-1),suggesting the promotion of AuNPs to photo-thermal evaporation.Meanwhile,PANI appreciatively assists AuNPs to display higher catalytic ability for the oxidative degradation of MO.Therefore,the removal of MO from water is obviously prompted by the water transpiration under sunlight with AuNP@PAAm-g-PANI cryogels,whose rate constant can reach to 0.320 h^(-1),being three folds of that for the sole absorption of MO.This transpiration-prompted photocatalytic degradation provides a fascinating route to eliminate organic pollutants and obtain pure water from wastewater simultaneously with sustainable sunlight energy.

Multifunctional chitosan/gelatin@tannic acid cryogels decorated with in situ reduced silver nanoparticles for wound healing

Background:Most traditional wound dressings only partially meet the needs of wound healing because of their single function.Patients usually suffer from the increasing cost of treatment and pain resulting from the frequent changing of wound dressings.Herein,we have developed a mutifunctional cryogel to promote bacterial infected wound healing based on a biocompatible polysaccharide.Methods:The multifunctional cryogel is made up of a compositive scaffold of chitosan(CS),gelatin(Gel)and tannic acid(TA)and in situ formed silver nanoparticles(Ag NPs).A liver bleeding rat model was used to evaluate the dynamic hemostasis performance of the various cryogels.In order to evaluate the antibacterial properties of the prepared cryogels,gram-positive bacterium Staphylococcus aureus(S.aureus)and gram-negative bacterium Escherichia coli(E.coli)were cultured with the cryogels for 12 h.Meanwhile,S.aureus was introduced to cause bacterial infection in vivo.After treatment for 2 days,the exudates from wound sites were dipped for bacterial colony culture.Subsequently,the anti-inflammatory effect of the various cryogels was evaluated by western blotting and enzyme-linked immunosorbent assay.Finally,full-thickness skin defect models on the back of SD rats were established to assess the wound healing performances of the cryogels.Results:Due to its porous structure,the multifunctional cryogel showed fast liver hemostasis.The introduced Ag NPs endowed the cryogel with an antibacterial efficiency of>99.9%against both S.aureus and E.coli.Benefited from the polyphenol groups of TA,the cryogel could inhibit nuclear factor-κB nuclear translocation and down-regulate inflammatory cytokines for an anti-inflammatory effect.Meanwhile,excessive reactive oxygen species could also be scavenged effectively.Despite the presence of Ag NPs,the cryogel did not show cytotoxicity and hemolysis.Moreover,in vivo experiments demonstrated that the biocompatible cryogel displayed effective bacterial disinfection and accelerated wound healing.Conclusions:The multifunctional cryogel,with fast hemostasis,antibacterial and anti-inflammation properties and the ability to promote cell proliferation could be widely applied as a wound dressing for bacterial infected wound healing.

Cryo-copolymerization preparation of dextran-hyaluronate based supermacroporous cryogel scaffolds for tissue engineering applications

Dextran-hyaluronate （Dex-HA） based supermacroporous cryogel scaffolds for soft tissue engineering were prepared by free radical cryo-copolymerization of aqueous solutions containing the dextran methacrylate （Dex-MA） and hyaluronate methacrylate （HA-MA） at various macromonomer concentrations under the freezing condition. It was observed that the suitable total concen- tration of macromonomers for the preparation of Dex-HA cryogel scaffold with satisfied properties was 5% （w/w） at the HA-MA concentration of 1% （w/v）, which was then used to produce the test scaffold. The obtained cryogel scaffold with 5% （w/w） macromonomer solution had high water permeability （5.1 × 10 ^-2m2） and high porosity （92.4%）. The pore diameter examined by scanning electron microscopy （SEM） was in a broad range of 50-135 um with the mean pore diameter of 91 um. Furthermore, the cryogel scaffold also had good elastic nature with the elastic modulus of 17.47±1.44 kPa. The culture of 3T3-L1 preadipocyte within the scaffold was investigated and observed by SEM. Cells clustered on the pore walls and grew inside the scaffold indicating the Dex-HA cryogel scaffold could be a promising porous biomaterial for applications in tissue engineering.

Bioactive gelatin cryogels with BMP-2 biomimetic peptide and VEGF:A potential scaffold for synergistically induced osteogenesis

A poor biocompatibility and bioactivity of invasive materials remains major problems for biomaterialbased therapy. In this study, we introduced gelatin scaffolds carrying both bone morphogenetic protein-2(BMP-2) biomimetic peptide and vascular endothelial growth factor-165(VEGF) that achieved controlled release, cell attachment, proliferation and differentiation. To promote osteogenesis with VEGF, we designed the BMP-2 biomimetic peptide that comprised BMP-2 core sequence oligopeptide(SSVPT), phosphoserine, and synthetic cell adhesion factor(RGDS). In vitro cell experiments, the scaffold was conducive to the adhesion and proliferation of rat bone marrow mesenchymal stem cells(r BMSCs). The micro-CT3 D reconstruction of the rat cranial bone defect model showed that bone regeneration patterns occurred from one side edge towards the center area implanted with the prepared cryogel, and tissue section staining analysis demonstrated that the scaffold with double-growth factor can synergistically accelerate bone regeneration. These findings suggested that the obtained gelatin cryogel could serve as a cell-responsive platform for biomaterial-based nonbearing bone repair.

γ-PGA/HEMA/PEG聚合物晶胶支架修复兔眼眶骨折缺损的实验研究

目的近年来,眶骨骨折发生率逐年增加,其治疗关键旨在修复缺损的眶骨,聚(γ-谷氨酸)/2-羟乙基甲基丙烯酸酯/聚(乙二醇)(γ-PGA/HEMA/PEG)聚合物晶胶是一种具有互连多孔结构的新型支架材料,研究旨在检验其在眼眶骨折缺损修复中的骨修复效果。方法采用低温凝胶技术制备了γ-PGA/HEMA/PEG聚合物晶胶。制备了兔的眼眶骨缺损模型,根据植入支架材料的不同分为3组,空白对照组、聚合物晶胶组(Gel组)、矿化聚合物晶胶组(M-gel组)。植入后8周和16周标本取材进行大体观察,通过影像学和组织学检查观察其血管生成和成骨效果。结果影像学检查结果表明,支架材料能有效促进眶骨缺损的修复,缺损区被骨组织完全替代。组织学结果表明,支架材料可以增加Runt相关转录因子2(Runx-2)、碱性磷酸酶(ALP)、骨桥蛋白(OPN)和血小板内皮细胞黏附分子1(CD31)的表达,这表明支架材料植入后血管生成和成骨能力增强。结论矿化聚合物晶胶是一种良好的眼眶骨折缺损修复的支架材料。

形状记忆双网络晶胶止血剂的制备及性能

以天然高分子材料羧甲基壳聚糖(CMCS)和海藻酸钠(SA)为基体,通过低温冷冻交联的方法制备了初始晶胶;再通过一步浸泡法负载Ca^(2+),得到可生物降解的形状记忆双网络晶胶止血剂CMCS_(x)-SA_(y)-Ca_(z)。采用FTIR和SEM对CMCS_(x)-SA_(y)-Ca_(z)进行了表征,并测试了它的机械性能和生物相容性。实验结果表明,CMCS与SA质量比为7∶3的CMCS_(7)-SA_(3)-Ca_(z)晶胶呈现出孔径为50~200μm的贯通大孔结构,并具有良好的力学性能和抗疲劳性,抗压强度最大可达9.55 kPa;在循环压缩5次后,形变与强度仍能较初始状态恢复80%以上;CMCS_(7)-SA_(3)-Ca_(z)具有良好的形状记忆功能,可以反复进行压缩固定与吸水复原。CMCS_(7)-SA_(3)-Ca_(z)的大孔连通结构有利于血液浓缩、血细胞聚集和凝血成分的阻滞,具有快速吸收血液的能力,并能迅速控制伤口出血。

分子印迹冰胶聚合物研究进展

冰胶是在低于体系凝固点以下,通过聚合或交联反应制备的疏松的、大孔状的凝胶,其在分析化学领域的应用,主要是将分子印迹技术的构效预知性、特异识别性与冰胶的多孔结构和高通量结合,构成"分子印迹冰胶法";分子印迹冰胶法在蛋白质分离纯化方面,对于保持蛋白质的生物活性,有独特的优势。冰胶通常制备成颗粒包埋型分子印迹冰胶填充柱或整体柱,也可制备成分子印迹选择性分离膜;所选的模板成分可以是无机离子、小分子或大分子,也可以是大分子上的某些片段;既可以是单分子(片段、离子),也可以是多种分子(片段、离子)的混和物,即混和模板法;既可以直接是目标物本身,还可以是目标物质的结构类似物、同位素标记物及目标物质的片段,即虚拟模板法;甚至还可直接以复杂样品中的高丰度组分作为模板制备分子印迹冰胶,使高丰度组分被选择性吸附,从而使低丰度成分的信号增强,即待定模板法。

冰胶印迹聚合物固定化脂肪酶的制备及催化性能

利用冰冻凝胶(cryogel,简称冰胶)印迹聚合物实现了脂肪酶的固定化。在脂肪酶存在的条件下,以过硫酸铵/亚硫酸氢钠为引发剂,由丙烯酰胺、N,N-亚甲基双丙烯酰胺、丙烯酸、烯丙胺共聚而得到印迹聚合物固定化酶。通过催化三油酸甘油酯与甲醇的酯交换反应,发现冰胶固定化脂肪酶、常规凝胶固定化脂肪酶、游离脂肪酶具有相似的催化性能。冰胶固定化酶与相应的凝胶固定化酶显示出类似的稳定性,而传质方面则优于常规凝胶固定化酶,因此冰胶印迹聚合物固定化有望成为一种具有吸引力的酶固定化方法。