温敏性抗菌水凝胶的制备与控释技术研究进展

温敏水凝胶是一类通过感知温度变化使自身发生相变的智能型聚合物凝胶,通过负载抗菌剂或抗菌性单体制备抗菌水凝胶是近年来药物控制释放、组织工程以及生物免疫等领域关注的热点。本文概述了负载抗菌剂型温敏性抗菌水凝胶的物理交联和化学交联制备技术的研究概况,着重阐述了温敏性抗菌水凝胶的孔径调控、制备材料调控、载药模式调控等技术的研究进展,并对温敏性抗菌水凝胶的控释技术应用前景,特别是在生物质材料领域的应用前景进行了展望。     

快速响应的温敏性聚(N-异丙基丙烯酰胺)水凝胶的合成及表征

快速响应的温敏性聚(N-异丙基丙烯酰胺)水凝胶的合成及表征;N-异丙基丙烯酰胺;水凝胶;温敏性;快速响应     

明胶-聚异丙基丙烯酰胺水凝胶的pH、温度敏感性

用明胶(Gel)和N 异丙基丙烯酰胺(NIPAM)为原料,制备了Gel/聚异丙基丙烯酰胺(PNIPAM)水凝胶;研究了不同含量的水凝胶的温度、pH敏感性。结果表明:温度对水凝胶pH敏感性的影响取决于水凝胶的组成。明胶含量高的水凝胶,其pH敏感性几乎不受温度的影响;当0.500.90时,pH值几乎不影响水凝胶的温敏性。     

温敏性水杨酸分子印迹水凝胶的合成与性能研究

以水杨酸为模板分子,丙烯酰胺为功能单体,N-异丙基丙烯酰胺为温敏单体,乙二醇二甲基丙烯酸酯为交联剂,偶氮二异丁腈为引发剂,采用本体聚合法,60℃热聚合制备了温度敏感的分子印迹(MIP)水凝胶,其最低临界溶解温度(LCST)在40℃左右.该分子印迹水凝胶对水杨酸显示了高的选择识别性,非分子印迹水凝胶则表现出低的选择性.温敏性分子印迹水凝胶的吸附容量达6.35 mg/g,是非印迹水凝胶的3.66倍.相对于未添加温敏单体的分子印迹聚合物,温敏性水杨酸分子印迹水凝胶对目标分子的吸附和洗脱效率分别提高33.3％和50％,并实现了温度响应的水凝胶结合、释放水杨酸的功能.     

变温反相悬浮聚合制备温度敏感性聚合物微凝胶

报道了一种利用变温的途径制备具有温度敏感性聚合物凝胶微粒的悬浮聚合方法.以正庚烷为连续相,过硫酸铵和四甲基乙二胺为引发剂,采用将具有反向温敏性的可降解大分子单体水溶液在低温下分散好以后再升高到聚合温度的变温反相悬浮聚合的方法制备了反向温敏性的可降解微凝胶.该方法避免了由于分散相在聚合温度下发生物理凝胶化所导致的分散困难等问题.考察了微凝胶的温敏性、粒径分布和降解行为等,并研究了油水比对微凝胶形貌的影响.     

快速响应的温敏性聚(N-异丙基丙烯酰胺)水凝胶 Ⅰ.以CaCO_3为成孔剂制备方法、表征及动力学研究

以不同粒径的CaCO3粒子为成孔剂 ,合成了快速响应的温敏性聚 (N 异丙基丙烯酰胺 ) (PNIPA)水凝胶 .利用扫描电镜观察到水凝胶具有特殊的孔状结构 ,得到水凝胶的孔径大小为几十微米左右 .动力学研究表明 ,该水凝胶在温敏膨胀或收缩时 ,具有快速的响应速率 ,在 10min内的失水率可达 90 % .比较了干凝胶和4 0℃下失水后的凝胶两种不同状态下水凝胶的膨胀曲线 ,发现两者的溶胀动力学曲线明显不同 ,前者的曲线有拐点 .同时发现与失水收缩速率相比 ,水凝胶具有较慢的吸水膨胀速率 .     

速响应的温敏性聚(N-异丙基丙烯酰胺)水凝胶Ⅰ.以CaCO3为成孔剂制备方法、表征及动力学研究

以不同粒径的CaCO3粒子为成孔剂,合成了快速响应的温敏性聚(N-异丙基丙烯酰胺)(PNIPA)水凝胶.利用扫描电镜观察到水凝胶具有特殊的孔状结构,得到水凝胶的孔径大小为几十微米左右.动力学研究表明,该水凝胶在温敏膨胀或收缩时,具有快速的响应速率,在10 min内的失水率可达90%.比较了干凝胶和40℃下失水后的凝胶两种不同状态下水凝胶的膨胀曲线,发现两者的溶胀动力学曲线明显不同,前者的曲线有拐点.同时发现与失水收缩速率相比,水凝胶具有较慢的吸水膨胀速率.     

温敏性微凝胶的研究技术

温敏性微凝胶因具有尺寸小、对温度的变化响应速度快、渗透性好等优点,所以在许多领域显示出良好的应用前景.温敏性微凝胶的应用性能取决于由其结构所决定的物理化学性能.为了深入了解温敏性微凝胶的结构与性能关系,研究人员利用不同技术手段进行了广泛研究.本文主要综述了显微技术、示差扫描量热技术、光散射技术、中子散射技术、核磁共振及荧光光谱等在温敏性微凝胶结构与性能研究中的应用、主要研究结果,并对微凝胶未来的研究方向提出了一些建议.     

磁性半互穿网络智能水凝胶的合成及性质评价

以甲基丙烯酸(MAA)、N-异丙基丙烯酰胺(NIPAAm)、丙烯酰胺(AM)为原料,N,N′-亚甲基双丙烯酰胺(MBA)为交联剂,利用IPN技术并结合磁性的γ-Fe2O3增强剂,在水溶液中制备了半互穿网络水凝胶(PMAA/PAM-NIPAAm/γ-Fe2O3),研究了水凝胶的溶胀性﹑热稳定性和电磁性。实验表明,水凝胶形成稳定的IPN互穿网络结构且该水凝胶具温度、pH双重敏感性和顺电磁性。所合成的水凝胶在低临界溶解温度31℃以下,具有明显正向温敏性,高于此温度,水凝胶的温度敏感性会逐渐减弱。产品成功克服了NIPAAm类水凝胶的温缩性。     

快速响应的温敏性聚（N—异丙基丙烯酰胺）水凝胶——Ⅰ.以CaCO3为成孔剂制备方法、表征及动力学研究

以不同粒径的CaCO3粒子为成孔剂，合成了快速响应的温敏性聚（N-异丙基丙烯酰胺）（PNIPA）水凝胶，利用扫描电镜观察到水凝胶具有特殊的孔状结构，得到水凝胶的孔径大小为几十微米左右，动力学研究表明，该水凝胶在温敏膨胀或收缩时，具有快速的响应速率，在10min内的失水率可达90%，比较了干凝胶和40℃下失水后的凝胶两种不同状态下水凝胶的膨胀曲线，发现两者的溶胀动力学曲线明显不同，前者的曲线有拐点，同时发现与失水收缩速率相比，水凝胶具有较慢的吸水膨胀速率。     

A novel thermoresponsive hydrogel with ion-recognition property through supramolecular host-guest complexation

A novel thermoresponsive hydrogel with ion-recognition property was prepared via free-radical cross-linking copolymerization of N-isopropylacrylamide (NIPAM) with benzo-18-crown-6-acrylamide (BCAm) as host receptor. Both chemical structures and stimuli-sensitive properties of the prepared poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) P(NIPAM-co-BCAm) hydrogel were characterized. The smart hydrogel could respond to both temperature and ion stimuli. When the crown ether units captured Ba2+ and formed stable BCAm/Ba2+ host-guest complexes, the lower critical solution temperature (LCST) of the hydrogel increased due to the repulsion among charged BCAm/Ba2+ complex groups and osmotic pressure within the hydrogel. Whereas crown ethers captured Cs+, the LCST shifted to a lower temperature because of the formation of 2:1 sandwich complexes. Unexpectedly, the LCST of the cross-linked P(NIPAM-co-BCAm) hydrogel in K+ solution did not shift to a higher temperature, which was definitely different from the previously reported linear P(NIPAM-co-BCAm) copolymer in K+ solution. The results of this work provide valuable information for development of dual thermo- and ion-responsive hydrogels which have potential applications in drug controlled-release systems or biomedical fields.     

An efficient method for the fabrication of temperature-sensitive hydrogel microactuators

In this article a new method for the photolithographical deposition of temperature-sensitive hydrogels is presented. The method can be used in conjunction with standard 365 nm UV-photolithography to accurately dimension and position temperature-sensitive hydrogel microactuators in a highly parallel fashion. A number of characteristics of the hydrogels were investigated. These include: the photolithographical reproduction quality, the effect of the crosslinking density in the hydrogels on their swelling behavior, the swelling hysteresis behavior, the effect of dimensional constraints on the swelling of the hydrogels and the effect of copolymerization with an ionizable comonomer on the temperature behavior of the hydrogels. The method presents a considerable improvement in the microfabrication of temperature-sensitive hydrogel microactuators and has potential for the mass-fabrication of these interesting microactuators.     

Controlling the properties of poly(amino ester urethane)–poly(ethylene glycol)–poly(amino ester urethane) triblock copolymer pH/temperature-sensitive hydrogel

A series of triblock copolymers composed of poly(ethylene glycol) (PEG) and poly(β-amino ester urethane) (PAEU) was synthesized and characterized. Its aqueous solution can be used as a non-cytotoxic, biodegradable, and pH/temperature-sensitive hydrogel system. The copolymer solutions exhibited sol-to-gel and gel-to-sol transitions with increasing pH and temperature, respectively. The properties of this hydrogel system, such as its sol–gel transition diagram, mechanical properties, and degradation rate, can be controlled by modulating the PEG molecular weight, PAEU block length, copolymer concentration, or structure of the monomers. The presence of urethane groups and ionized tertiary amine groups in the copolymer solution at lightly acidic pH may lead to a strong interaction of the copolymer with formulated bioactive therapeutic agents, while the existence of the gel state under physiological conditions (37 °C, pH 7.4) may enable this copolymer hydrogel to be applicable as a drug/protein carrier.     

Investigation of nanocomposite PNIPAm-g-graphene with pre-lower critical solution temperature rapid thermal response function for chip adaptive cooling: A molecular dynamics and computational fluid dynamics simulations

Temperature-sensitive hydrogels have been widely used for rapid adaptive cooling in electronic device thermal management with promising applications. However, existing temperature-sensitive hydrogels can only regulate the flow in the chip cooling system after the ambient temperature reaches their lower critical solution temperature (LCST). Before reaching LCST, effective rapid heat dissipation for electronic chips is not achievable. This study aims to develop a temperature-sensitive hydrogel that can provide assisted adaptive cooling for electronic chips before reaching its LCST. This requires the hydrogel to have a thermal conductivity far surpassing existing hydrogel materials. Using the temperature-sensitive hydrogel PNIPAm and graphene molecules as base materials, this research utilized molecular dynamics simulations to graft graphene molecules onto PNIPAm molecules in different ways, resulting in the temperature-sensitive hydrogel material PNIPAm-g-graphene. Non-equilibrium molecular dynamics (NEMD) was employed to calculate the thermal conductivity of this material under different temperature conditions. The results indicate that the thermal conductivity of PNIPAm-g-graphene can reach up to 1.95474 W/m K (graphene grafted at  CH₃ functional group, temperature at 280 K). Compared to the thermal conductivity of PNIPAm under the same conditions (0.45 W/m K), the increase in thermal conductivity is significant, demonstrating excellent thermal conductivity compared to PNIPAm. Subsequently, this study analyzed the underlying mechanisms of different thermal conductivities in materials obtained by grafting graphene molecules at different points using the method of overlap in Phonon Density of States Curves (PDOS) from the perspective of interfacial thermal conduction. Finally, through computational fluid dynamics (CFD) simulations, this study investigates the chip's adaptive cooling performance with PNIPAm-g-graphene material. The results show that, compared to traditional temperature-sensitive hydrogels, PNIPAm-g-graphene can achieve efficient adaptive cooling of chip hotspots before the cooling fluid temperature reaches its LCST value. This finding is significant for the field of chip cooling. The study proposes a new method for rapid, adaptive cooling of chip hotspots and explores its feasibility from the perspectives of molecular dynamics and CFD simulation. It holds importance in the thermal management of electronic devices and the rapid adaptive cooling of electronic chips.     

Synthesis of Temperature-Sensitive Poly(N-isopropylacrylamide) Hydrogel with Improved Surface Property

A new PNIPA hydrogel was synthesized by carrying out the polymerization in the gelated corn starch aqueous solution. This PNIPA hydrogel has an improved surface property and does not form the disadvantageous bubbles during the shrinking process. This change is due to the hydrogen bonds between the corn starch and the hydrophilic side groups of the PNIPA chains, which let the starch act as the long graft-like chains of the PNIPA hydrogel. During the reswelling process, this PNIPA hydrogel exhibits a sigmoidal swelling pattern. This hydrogel with improved surface property may be very useful for the potential applications of the temperature-sensitive hydrogel. Copyright 2000 Academic Press.     

Temperature-sensitive polyamidoamine dendrimer/poly(N-isopropylacrylamide) hydrogels with improved responsive properties

Novel temperature-sensitive poly(N-isopropylacrylamide)/amine-terminated polyamidoamine dendrimer G6-NH2 hydrogels with fast responsive properties were synthesized by forming semi-interpenetrating polymeric networks. In contrast to the conventional PNIPA hydrogel, these new gels showed rapid shrinking rate at the temperature above lower critical solution temperature (LCST), and exhibited higher equilibrium swelling ratio at room temperature. All these properties might be attributed to the incorporation of polyamidoamine dendrimer G6-NH2, which forms water-releasing channels and increases the hydrophilicity of PNIPA network. The novel hydrogels have potential applications in drug and gene delivery.     

A parallel approach to the discovery of carrier delivery vehicles to enhance antigen immunogenicity

As part of an ongoing effort to generate human and murine monoclonal antibodies against poorly immunogenic tumor-associated antigens we have merged the rapidly expanding disciplines of parallel polymer synthesis and controlled-release technology with immunology to produce a rapid and generic approach to improve the immunogenicity of carrier-bound antigens. The process involves three stages: An array of cross-linked hydrogel materials containing a carrier protein (at various concentrations) is prepared in parallel in one step. The array is then screened in mice to determine the most effective hydrogel at enhancing the immunogenicity of the encapsulated versus nonencapsulated carrier. Finally, the most efficient hydrogel is prepared containing the critical carrier-antigen conjugate and is used for immunization protocols. The strategy was successful for the BSA-glycoconjugate of the tumor-associated antigen GM3 analogue 4. When encapsulated within the hydrogel array member most efficient at elevating BSA immunogenicity, the BSA-4 glycoconjugate was significantly more immunogenic that when administered as a free antigen.     

A novel sol–gel strategy to prepare temperature-sensitive hydrogel for encapsulation of protein

A novel sol–gel strategy was proposed to prepare temperature-sensitive hydrogel including the copolymerization of N-isopropylacrylamide and 3-methacryloxypropyl-trimethoxy silane and then the hydrolysis and condensation of the linear polymers through the sol–gel process under extra-mild conditions. Bovine serum albumin, as a model protein, was loaded into the hydrogel matrix to investigate the encapsulation and release properties. Experimental results indicated that the preparation conditions were valuable for the loading and release of biomacromolecules.     

Drug release of pH/temperature-responsive calcium alginate/poly(N-isopropylacrylamide) semi-IPN beads

A series of semi-interpenetrating, polymer network (semi-IPN), hydrogel beads, composed of calcium alginate (Ca-alginate) and poly(N-isopropylacrylamide) (PNIPAAM), were prepared for a pH/temperature-sensitive drug delivery study. The equilibrium swelling showed the independent pH- and thermo- responsive nature of the developed materials. At pH=2.1, the release amount of indomethacin incorporated into these beads was about 10% within 400 min, while this value approached to 95% at pH=7.4. The release rate of the drug was higher at 37 degrees C than that at 25 degrees C and increased slightly with increasing PNIPAAM content. These results suggest that the Ca-alginate/PNIPAAM beads have the potential to be used as an effective pH/temperature sustainable delivery system of bioactive agents. [GRAPHS: SEE TEXT] A summary of the temperature- and pH-dependence on the release of the drug over a period of 450 min. The effect of the temperature on the swelling of the beads is shown in the inset.