Fluorescent Double Network Hydrogels with Ionic Responsiveness and High Mechanical Properties for Visual Detection

We developed a fluorescent double network hydrogel with ionic responsiveness and high mechanical properties for visual detection.The nanocomposite hydrogel of laponite and polyacrylamide serves as the first network,while the ionic cross-linked hydrogel of terbium ions and sodium alginate serves as the second network.The double-network structure,the introduction of nanoparticles and the reversible ionic crosslinked interactions confer high mechanical properties to the hydrogel.Terbium ions are not only used as the ionic cross-linked points,but also used as green emitters to endow hydrogels with fluorescent properties.On the basis of the “antenna effect” of terbium ions and the ion exchange interaction,the fluorescence of the hydrogels can make selective responses to various ions(such as organic acid radical ions,transition metal ions) in aqueous solutions,which enables a convenient strategy for visual detection toward ions.Consequently,the fluorescent double network hydrogel fabricated in this study is promising for use in the field of visual sensor detection.

Semi-Interpenetrating Novolac-Epoxy Thermoset Polymer Networks Derived from Plant Biomass

Bio-based phenol-formaldehyde polymer (BioNovolac) was developed by reacting molar excess of bio-oil/phenolwith formaldehyde in acidic medium. Glycidyl 3,5-diglycidoxybenzoate (GDGB), was prepared by directglycidylation of α-resorcylic acid (RA), a naturally occurring phenolic monomer. GDGB was crosslinked in thepresence of BioNovolac by anionic polymerization. Fourier transform infrared spectroscopy (FTIR) confirmedthe formation of semi-interpenetrating polymer networks. The glass transition temperature and moduli of biobasedcrosslinked systems were observed to increase with increasing GDGB content. Active chain density andmass retention measured by dynamic mechanical analysis (DMA) and Soxhlet extraction, respectively, indicated ahigh crosslink density of the cured networks. Scanning electron microscopy (SEM) images depicted thehomogeneity of the bulk phase. The preparation of bio-based epoxy-novolac thermoset network resulted inreduced consumption of petroleum-based chemicals.

Semi-interpenetrating network anion exchange membranes based on quaternized polyvinyl alcohol/poly(diallyldimethylammonium chloride)

The semi-interpenetrating network anion exchange membranes(AEMs)based on quaternized polyvinyl alcohol(QPVA)and poly(-diallyldimethylammonium chloride)(PDDA)are synthesized.The chemical cross-linking structure is formed between hydroxyl groups of QPVA and aldehyde groups of glutaraldehyde(GA),which makes PDDA more stable embed in the QPVA matrix and also improves the mechanical properties and dimensional stability of AEMs.Due to the phase separation phenomenon of AEMs swelling in water,a microporous structure may be formed in the membrane,which reduces the transmission resistance of hydroxide ions and provides a larger space for the transfer of hydroxide ions,thus improving the conductivity.The ring structure of PDDA is introduced as a cationic group to transfer hydroxide ions,and shields the nucleophilic attack of the hydroxide ions through the steric hindrance effect,which improves alkaline stability.The hydroxide conductivity of semi-interpenetrating network membrane(QPVA/PDDA0.5-GA)is 36.5 mS cm^(-1) at 60℃.And the membrane of QPVA/PDDA0.5-GA exhibits excellent mechanical property with maximum tensile strength of 19.6 MPa.After immersing into hot 3 mol L^(-1) NaOH solutions at 60℃ for 300 h,the OHconductivity remains 78%of its initial value.The semi-interpenetrating network AEMs with microporous structure exhibit good ionic conductivity,mechanical strength and alkaline durability.

Tough Semi-interpenetrating Polyvinylpyrrolidone/Polyacrylamide Hydrogels Enabled by Bioinspired Hydrogen-bonding Induced Phase Separation

Semi-interpenetrating(semi-IPN)hydrogels formed by the continuous interpenetration of cross-linked polymer network and linear non-crosslinked polymer with multifunctionality are widely used in biomedical and other fields.However,the negative impact of linear polymer on the homogeneity of the cross-linked network often leads to a decrease in the mechanical properties of semi-IPN hydrogels and severely limits their applications.Herein,a bioinspired hydrogen-bonding induced phase separation strategy is presented to construct the tough semi-IPN polyvinylpyrrolidone/polyacrylamide hydrogels(named PVP/PAM hydrogels),including the linear polymer polyvinylpyrrolidone(PVP)and cross-linked polyacrylamide(PAM)network.The resultant PVPx/PAM hydrogels exhibit unique phase separation induced by the hydrogen bonding between PVP and PAM and affected by the amount of substance of PVP.Meanwhile,the phase separation of PVPx/PAM hydrogels results in excellent mechanical properties with a strain of 2590%,tensile strength of 0.28 MPa and toughness of 2.17 MJ/m^(3).More importantly,the hydrogen bonding between PVP and PAM firstly disrupts to dissipate energy under external forces,so the PVPx/PAM hydrogels exhibit good self-recovery properties and outperform chemically cross-linked PAM hydrogels in impact resistance and damping applications.It is believed that the PVPx/PAM hydrogels with hydrogen-bonding induced phase separation possess more potential application prospects.

A Double Network Hydrogel with High Mechanical Strength and Shape Memory Properties

Double network(DN)hydrogels as one kind of tough gels have attracted extensive at-tention for their potential applications in biomedical and load-bearing fields.Herein,we import more functions like shape memory into the conventional tough DN hydro-gel system.We synthesize the PEG-PDAC/P(AAm-co-AAc)DN hydrogels,of which the first network is a well-defined PEG(polyethylene glycol)network loaded with PDAC(poly(acryloyloxyethyltrimethyl ammonium chloride))strands,while the second network is formed by copolymerizing AAm(acrylamide)with AAc(acrylic acid)and cross-linker MBAA(N;N′-methylenebisacrylamide).The PEG-PDAC/P(AAm-co-AAc)DN gels exhibits high mechanical strength.The fracture stress and toughness of the DN gels reach up to 0.9 MPa and 3.8 MJ/m^3,respectively.Compared with the conventional double network hydrogels with neutral polymers as the soft and ductile second network,the PEG-PDAC/P(AAm-co-AAc)DN hydrogels use P(AAm-co-AAc),a weak polyelectrolyte,as the second network.The AAc units serve as the coordination points with Fe^3+ions and physically crosslink the second network,which realizes the shape memory property activated by the reducing ability of ascorbic acid.Our results indicate that the high mechanical strength and shape memory properties,probably the two most important characters related to the potential application of the hydrogels,can be introduced simultaneously into the DN hydrogels if the functional monomer has been integrated into the network of DN hydrogels smartly.

A double-network hydrogel for the dynamic compression of the lumbar nerve root

Current animal models of nerve root compression due to lumbar disc herniation only assess the mechanical compression of nerve roots and the inflammatory response. Moreover, the pressure applied in these models is static, meaning that the nerve root cannot be dynamically compressed. This is very different from the pathogenesis of lumbar disc herniation. In this study, a chitosan/polyacrylamide double-network hydrogel was prepared by a simple two-step method. The swelling ratio of the double-network hydrogel increased with prolonged time, reaching 140. The compressive strength and compressive modulus of the hydrogel reached 53.6 and 0.34 MPa, respectively. Scanning electron microscopy revealed the hydrogel's crosslinked structure with many interconnecting pores. An MTT assay demonstrated that the number of viable cells in contact with the hydrogel extracts did not significantly change relative to the control surface. Thus, the hydrogel had good biocompatibility. Finally, the double-network hydrogel was used to compress the L4 nerve root of male sand rats to simulate lumbar disc herniation nerve root compression. The hydrogel remained in its original position after compression, and swelled with increasing time. Edema appeared around the nerve root and disappeared 3 weeks after operation. This chitosan/polyacrylamide double-network hydrogel has potential as a new implant material for animal models of lumbar nerve root compression. All animal experiments were approved by the Animal Ethics Committee of Neurosurgical Institute of Beijing, Capital Medical University, China(approval No. 201601006) on July 29, 2016.

Improving physical properties of poly(vinyl alcohol)/montmorillonite nanocomposite hydrogels via the Hofmeister effect

Hydrogel is a kind of three-dimensional crosslinked polymer material with high moisture content.However,due to the network defects of polymer gels,traditional hydrogels are usually brittle and fragile,which limits their practical applications.Herein,we present a Hofmeister effect-aided facile strategy to prepare high-performance poly(vinyl alcohol)/montmorillonite nanocomposite hydrogels.Layered montmorillonite nanosheets can not only serve as crosslinking agents to enhance the mechanical properties of the hydrogel but also promote the ion conduction.More importantly,based on the Hofmeister effect,the presence of(NH_(4))_(2)SO_(4)can endow nanocomposite hydrogels with excellent mechanical properties by affecting PVA chains'aggregation state and crystallinity.As a result,the as-prepared nanocomposite hydrogels possess unique physical properties,including robust mechanical and electrical properties.The as-prepared hydrogels can be further assembled into a high-performance flexible sensor,which can sensitively detect large-scale and small-scale human activities.The simple design concept of this work is believed to provide a new prospect for developing robust nanocomposite hydrogels and flexible devices in the future.

Progress of High Strength Double-Network Hydrogels

The design principles and preparation methods of the double-network hydrogels are reviewed. In addition,the application of the double-network hydrogels in different fields is also introduced.

Fluorinated semi-interpenetrating polymer networks for enhancing the mechanical performance and storage stability of polymer-bonded explosives by controlling curing and phase separation rates

Herein, the effect of fluoropolymer binders on the properties of polymer-bonded explosives(PBXs) was comprehensively investigated. To this end, fluorinated semi-interpenetrating polymer networks(semiIPNs) were prepared using different catalyst amounts(denoted as F23-CLF-30-D). The involved curing and phase separation processes were monitored using Fourier-transform infrared spectroscopy, differential scanning calorimetry, a haze meter and a rheometer. Curing rate constant and activation energy were calculated using a theoretical model and numerical method, respectively. Results revealed that owing to its co-continuous micro-phase separation structure, the F23-CLF-30-D3 semi-IPN exhibited considerably higher tensile strength and elongation at break than pure fluororubber F2314 and the F23-CLF-30-D0 semi-IPN because the phase separation and curing rates matched in the initial stage of curing.An arc Brazilian test revealed that F23-CLF-30-D-based composites used as mock materials for PBXs exhibited excellent mechanical performance and storage stability. Thus, the matched curing and phase separation rates play a crucial role during the fabrication of high-performance semi-IPNs;these factors can be feasibly controlled using an appropriate catalyst amount.

单宁酸改性互穿网络水凝胶促进断裂跟腱术后的组织重塑

背景:跟腱断裂术后的再生与重塑是临床治疗的难点,组织工程水凝胶材料为促进跟腱修复提供了可能。目的:探究单宁酸改性互穿网络水凝胶对大鼠断裂跟腱组织再生与重塑的作用。方法:①通过蓝光照射及CaSO4溶液浸泡交联制备单宁酸改性互穿网络水凝胶,表征水凝胶的微观形貌、力学性能、黏附性能、体外释药性能与生物相容性。②取30只SD大鼠,采用随机数字表法分为假手术组、手术组与水凝胶组,每组10只,后2组建立右后肢跟腱断裂模型,手术组采用改良Kessler法将断裂跟腱重新缝合,水凝胶组采用相同术式缝合断裂跟腱后将单宁酸改性互穿网络水凝胶贴片完全缠绕包裹于断端接合处。术后4周,对断裂跟腱进行影像学检查、组织学评价、生物力学测试及炎症因子水平检测。结果与结论:①扫描电镜下可见单宁酸改性互穿网络水凝胶呈多孔微观结构,孔径为3-10μm,并且水凝胶具备良好的体外释药性能、黏附强度与拉伸强度;CCK-8检测与活/死染色显示,该水凝胶对大鼠骨髓间充质干细胞增殖活性无明显影响,具备良好的生物相容性。②MRI成像显示,与手术组比较,水凝胶组大鼠跟腱呈均一低信号,跟腱前后径厚度减小,与周围组织分界更为明确,表现更接近假手术组。苏木精-伊红与Masson染色显示,手术组大鼠跟腱纤维排列松散混乱,细胞密度增加且排布杂乱,伴有明显炎性细胞浸润,部分区域出现腱内骨化;水凝胶组大鼠跟腱纤维排列有序,细胞密度降低且排布规整,炎性细胞浸润明显减少。手术组大鼠跟腱的拉伸强度低于假手术组(P<0.05),水凝胶组大鼠跟腱的拉伸强度高于手术组(P<0.05)。与假手术组比较,手术组大鼠跟腱中白细胞介素1β、白细胞介素6及肿瘤坏死因子α质量浓度及mRNA表达升高(P<0.05);与手术组比较,水凝胶组3种炎症因子水平及mRNA表达降低。③结果表明,单宁酸改性互穿网络水凝胶可显著抑制局部炎症反应、促进断裂跟腱组织重塑。

单宁酸-纤维素/聚乙烯醇/聚丙烯酸双网络水凝胶的制备及性能

通过将单宁酸(TA)和纤维素纳米纤维(CNF)嵌入硼砂-聚乙烯醇(PVA)/聚丙烯酸(PAA)水凝胶网络,利用一锅法制备了TA/CNF-g-PVA/PAA纳米复合双网络水凝胶。采用红外光谱、扫描电镜、热重分析、溶胀、黏附及生物实验对其进行结构表征和性能测试。结果表明,当TA和CNF的质量比为1:2时,PATCP水凝胶在猪皮上的黏附强度最高达5.64 kPa;PATCP水凝胶还表现出显著的抗溶胀性能,其平衡溶胀率仅为PVA/PAA水凝胶的3/5;PATCP水凝胶对大肠杆菌和金黄色葡萄球菌的抑菌圈最大宽度分别为17 mm和13 mm;该水凝胶具有一定的自愈合性能,水凝胶溶血率均在2%以下,且水凝胶提取液中细胞存活率均在89%以上,表现出优异的生物相容性。

生物质氧化石墨烯基双网络水凝胶球的制备与吸附性能

为了减轻废弃甘蔗渣给环境带来的压力,以废弃甘蔗渣为原料,制备了生物质氧化石墨烯(BGO)。以Ca^(2+)交联的海藻酸钠(SA)为第一交联网络,以BGO为异质晶核,借助于冷冻-解冻法诱导聚乙烯醇(PVA)结晶交联,制备了PVA/SA/BGO双网络水凝胶球,考察了PVA/SA/BGO双网络水凝胶球的结构、形貌以及对有机染料结晶紫(CV)的吸附性能。结果表明:所得BGO具有片层结构和丰富的含氧基团。PVA/SA/BGO双网络水凝胶球对CV的最大吸附容量为460.21 mg·g^(-1),吸附过程符合Langmuir等温吸附模型和拟二级动力学吸附模型。

海藻酸钠/聚丙烯酰胺复合水凝胶的壳聚糖增韧

以天然多糖海藻酸钠(SA)、丙烯酰胺(AM)单体为基础原料构筑双网络水凝胶,引入不同含量的壳聚糖(CS),增强水凝胶的力学韧性。通过扫描电子显微镜、红外光谱、X射线衍射仪及热失重分析仪等表征水凝胶的形貌特征、网络交联结构及热学性能,分析SA/聚丙烯酰胺(PAM)水凝胶的交联机理。结果表明,水凝胶的韧性随CS含量的增加而增加,CS低含量时韧性增加由伸长能力增加引起,而高添加时则因强度伸长同步增加引起,添加10%CS的水凝胶其韧性值达到2.50×10~5 kJ/m~3,明显高于添加5%和7.5%CS的水凝胶;对水凝胶定伸长循环拉伸,其弹性回复率随所定伸长率的增加而有所降低,在25%定伸长时均高于98%,而在200%时只高于90%,其中添加10%CS的水凝胶弹性最佳,且有较强的断裂应力(0.249 MPa)和断裂伸长率(1 635.65%),在200%及以内定伸长循环拉伸时具有优异的回复能力。

聚苯胺复合多网络水凝胶的制备和性能研究

为了研究醋酸掺杂聚苯胺(PANI)复合聚乙烯醇(PVA)/聚丙烯酸钠(PAAS)多网络水凝胶的电化学性能和光敏性能,采用水溶液共聚法制得PVA/PAAS多网络水凝胶,然后用原位聚合法将PANI与水凝胶复合生成导电水凝胶,即PANI/PVA/PAAS水凝胶;利用紫外-可见光吸收光谱(UV)、傅利叶红外光谱(FT-IR)、X射线衍射(XRD)和扫描电子显微镜图(SEM)对PANI粉体进行表征,以探究PANI粉体的结构和形貌。结果表明:PANI粉体具有不错的晶体结构以及在掺杂醋酸浓度为0.12mol/L时具有最好的棒状形貌特征。通过循环伏安法(CV)和恒电流充放电测试(CP)证明了导电水凝胶在醋酸掺杂浓度为0.12mol/L时具有最大的面积比电容216.5mF/cm^(2),使该材料有发展成超级电容器的前景;通过光敏感性测试证明了在掺杂醋酸浓度为0.20mol/L时,导电水凝胶具有最好的光敏性能,说明该材料有发展成光敏感材料的潜力。

双网络水凝胶在医药领域的应用及研究进展

双网络(DN)水凝胶是一种具有三维网络结构的高分子生物黏附材料,采用刚性网络与柔性网络互穿的形式对传统单网络(SN)水凝胶进行了强化,具备较高的机械强度与韧性,被广泛应用于医药领域。近年来,出现了多种新型DN水凝胶,为传统DN水凝胶赋予了快速凝胶化、强组织附着力等更多优势,进一步拓宽了DN水凝胶的应用范围。现将近年来DN水凝胶在医药领域的应用及发展现状进行综述。

Polyzwitterionic cross-linked double network hydrogel electrolyte enabling high-stable Zn anode

Zn metal anode suffers from dendrite issues and passive byproducts,which severely plagues the practical application of aqueous Zn metal batteries.Herein,a polyzwitterionic cross-linked double network hydrogel electrolyte composed of physical crosslinking(hyaluronic acid)and chemical crosslinking(synthetic zwitterionic monomer copolymerized with acrylamide)is introduced to overcome these obstacles.On the one hand,highly hydrophilic physical network provides an energy dissipation channel to buffer stress and builds a H_(2)O-poor interface to avoid side reactions.On the other hand,the charged groups(sulfonic and imidazolyl)in chemical crosslinking structure build anion/cation transport channels to boost ions’kinetics migration and regulate the typical solvent structure[Zn(H_(2)O)_(6)]^(2+)to R-SO_(3)^(−)[Zn(H_(2)O)_(4)]^(2+),with uniform electric field distribution and significant resistance to dendrites and parasitic reactions.Based on the above functions,the symmetric zinc cell exhibits superior cycle stability for more than 420 h at a high current density of 5 mA·cm^(−2),and Zn||MnO_(2)full cell has a reversible specific capacity of 150 mAh·g^(−1)after 1000 cycles at 2 C with this hydrogel electrolyte.Furthermore,the pouch cell delivers impressive flexibility and cyclability for energy-storage applications.

pH响应型形状记忆复合水凝胶制备及性能研究

通过在聚乙烯醇(PVA)网络中引入动态亚胺键,成功制备了具有pH响应性能的形状记忆水凝胶,并对其微观形貌、力学性能和形状记忆性能进行了研究。结果表明,浸泡pH=10的NaOH溶液后,水凝胶内部交联度提高,网络更加致密,其最高拉伸强度和最大断裂伸长率分别可达(68±0.5)kPa和200%,这表明在碱性条件下,可在聚合物网络中成功引入可逆的动态亚胺键。此外,水凝胶具有形状记忆性能,并且随着壳聚糖季铵盐(HACC)与氧化硫酸软骨素(OCS)质量比的降低,水凝胶的形状固定率与形状恢复率都呈上升趋势,且最优形状固定率和形状恢复率均在80%以上。该pH响应型形状记忆水凝胶,凭借高含水率、良好的生物相容性和独特的刺激响应性等特点,在信息储存与解密、航空航天等领域具有良好的应用前景。

机械训练自增强复合水凝胶的制备及性能研究

以2-甲基-2-丙烯酰胺基丙磺酸钠(NaAMPS)、聚乙烯醇(PVA)、羧甲基纤维素(CMC)作为原料,采用N,N′-亚甲基双丙烯酰胺作为交联剂,2-氧基戊二酸作为引发剂,紫外光引发NaAMPS化学交联形成凝胶第一重网络;采用循环冷冻-解冻方法使PVA链间通过氢键作用形成凝胶第二重网络;采用Al^(3+)与CMC的羧基之间的离子络合作用形成凝胶第三重网络,制备得到PNaAMPS/PVA/CMC-Al^(3+)复合水凝胶。对凝胶进行微观形貌表征、力学性能测试。结果表明:在形成第一、二重网络结构后,水凝胶内部网络变得更为致密,PVA间氢键的形成使凝胶的断裂强度由14kPa提升至53kPa;CMC-Al^(3+)的第三重网络形成后凝胶的断裂强度提升至127kPa。此外,将N-异丙基丙烯酰胺(NIPAM)作为预聚合单体加入凝胶中,凝胶在机械训练后表现出断裂应力自增强的效果,在机械训练应变为40%时,断裂强度提升23%,随着机械训练应变由40%增至160%,凝胶的断裂强度提升56%。该水凝胶通过机械训练诱导的结构破坏并重建过程实现了力学性能自增强,拓宽了在各领域中的实际应用,可为用于软机器人和智能设备等应用的自增强材料奠定基础。

基于高缠结纤维素水凝胶的力学作用机制研究

采用丙烯酰胺(AM)和羧甲基纤维素(CMC)构建高力学性能双网络(DN)水凝胶,探讨第一网络聚丙烯酰胺(PAM)的交联与缠结以及第二网络CMC的氢键作用,对水凝胶力学性能的作用机制。研究结果表明:对于第一网络,PAM在C=10^(-5)(C=n_(交联剂)/n_(单体)为水凝胶的交联度)下能形成显著的缠结结构,在应力作用下能通过滑动分子链逐渐形成缠结结构来实现能量耗散;PAM在C=10^(-2)下会形成高交联网络,在应力作用下通过化学键的断裂来耗散能量。对于第二网络,当水凝胶中CMC的质量分数Q=5.0%时,通过冻融能形成显著的氢键,并有效提高网络的作用力,从而提高水凝胶的力学性能。在C=10^(-5)、Q=5.0%时,水凝胶的应力达到0.328 MPa。CMC较大的渗透压会引起凝胶的溶胀,降低聚合物密度。此外,引入CMC还会影响第一网络PAM的缠结结构。

可缓释富血小板血浆生长因子的新型自组装多肽水凝胶制备及性能表征

背景:富血小板血浆水凝胶由于生长因子的突发释放与伤口部位蛋白酶的快速清除,导致生长因子在伤口部位的停留时间较短,近年来研究者关注利用水凝胶材料包封富血小板血浆,以改善富血小板血浆水凝胶的不足。目的:制备自组装多肽-富血小板血浆水凝胶,探究其对富血小板血浆生物活性因子释放的影响。方法:采用固相合成法合成自组装多肽,以D-PBS配制成溶液。将不同体积的多肽溶液分别与富血小板血浆、氯化钙/凝血酶溶液混合制备水凝胶,使体系中多肽的最终质量分数分别为0.1%,0.3%,0.5%,观察成水凝胶状态,并体外检测富血小板血浆中生长因子释放情况。将质量分数1%多肽溶液与质量分数1%人血清白蛋白溶液混合激发多肽自组装,使多肽的最终质量分数分别为0.1%,0.3%,0.5%,观察液体流动状态,并检测自组装多肽的流变力学性能。通过扫描电镜与透射电镜观察多肽(质量分数分别为0.1%,0.001%)-人血清白蛋白溶液的微观结构。结果与结论:①不同体积多肽溶液与富血小板血浆均可形成水凝胶,与富血小板血浆水凝胶相比,0.1%,0.3%多肽-富血小板血浆凝胶可缓解表皮生长因子、血管内皮生长因子的突发释放,延长释放时间至48 h。②添加人血清白蛋白后,0.1%多肽组仍呈流动液体,0.3%多肽组呈半液体状态,0.5%多肽组激发自组装形成水凝胶,确定富血小板血浆中人血清白蛋白可激发多肽自组装;随着多肽质量分数的提高,自组装多肽的存储模量越高,越容易成胶。③透射电镜下可见,添加人血清白蛋白前,多肽纳米纤维较短且无序堆积;添加人血清白蛋白后,多肽纳米纤维明显变长,并且相互交联成束,形成致密的纤维网络结构。扫描电镜下可见,添加人血清白蛋白前,多肽呈无序堆积的片状结构;添加人血清白蛋白后,多肽自组装成相互交联且有序密集排列的多孔状结构。④结果显示,新型自组装多肽可由富血小板血浆激发自组装,根据人血清白蛋白与多肽的比例可精准调节自组装效果,且多肽对富血小板血浆生长因子有缓释作用,可作为一种新型的生物材料应用于组织修复。