Aims: The aims of this study are to synthesize new derivatives of sodium alginate that improve the inherent properties, such as hydrogel strengthening, and create environmental sensitivity, such as pH sensitivity, for use in drug delivery. Background: Today, hydrogels, due to outstanding properties such as biodegradability, biocompatibility, mechanical properties, and response to stimuli properties, are widely used as harmless biomaterials in various fields in drug delivery, wound dressing, and tissue engineering. Stimulus-sensitive polymers significantly respond to slight changes in their environment. Different types of stimuli are used to influence the properties of polymers, the most important of which are temperature and pH because these are two vital factors in the human body; hence, temperature-sensitive and pHsensitive hydrogels have been extensively studied. The ability to absorb water and swell the hydrogel is due to hydrophilic chains in the hydrogel network, and water absorption by hydrogel can be controlled by response to the stimuli. Since hydrogels mimic human tissue, the ability to retain water in them is essential. As a result, it is considered in many biomedical drug delivery systems. Stimulusresponsive swelling can control diffusion out of and into the hydrogel network, which allows temporal and spatial control of drug release. When a drug is loaded onto a biodegradable and stimulisensitive hydrogel, the drug delivery system has the added advantage of sustained release of the drug, which reduces side effects. Methods: In this study, two different hydrocarbons, [1,3-diaminopropane (DAP)] as a short-chain hydrocarbon, and [1,7-diaminoheptane (DAH)] as a long-chain hydrocarbon were grafted onto three types ofsodium alginate (SA), through amide bond linkages. The hydrogel copolymer matrices were compared with sodium alginate (SA) beads. The graft copolymers were characterized using FTIR, 1HNMR, XRD spectroscopy, elemental analysis (CHNS) and thermal analysis (TGA, DTA and DSC). An environmental scanning electron microscope (ESEM) was used to investigate the surface morphology of hydrogels. Results: Effects of variables such as the length of hydrocarbon chains cross-linked to alginate, temperature, pH, and cross-linkers on the properties of hydrogels investigated in the temperature range of 2-70 ˚C and two different pH values (4.4 and 7.4). The results showed that when the hydrocarbon chain length of diamines decreases, the extent of cross-linking and strength of the hydrogels are increased. Other results suggest that the hydrogels obtained from high-viscosity alginate derivatives had positive pH sensitivity. Hydrogels prepared in this study demonstrated good mechanical and swelling ratios that are necessary for wound dressing. Conclusion: DAP-g-SA and DAH-g-SA pH-sensitive hydrogels were successfully synthesized through amide bond linkages. The new synthesis derivatives showed lower swelling levels at low pH (4.4). In contrast, their swelling levels at higher pH (7.4) were significantly enhanced. Higher swelling degree could be obtained at high pH. pH-responsive hydrogels are especially useful for various biological applications due to their unique feature of controlled swelling, biodegradability, biocompatibility, and fluid retention in their network structures. pH-responsive hydrogels, as intelligent systems, can be used in controlled-release drug delivery systems such as insulin delivery.

中文翻译：

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用于组织工程和药物输送的新型 pH 响应性胺化海藻酸盐衍生物水凝胶的合成和表征

目的：本研究的目的是合成新的海藻酸钠衍生物，以改善其固有特性（例如水凝胶强化），并产生环境敏感性（例如 pH 敏感性），用于药物输送。背景：如今，水凝胶由于具有生物可降解性、生物相容性、机械性能和刺激响应性能等优异性能，作为无害生物材料被广泛应用于药物输送、伤口敷料和组织工程等各个领域。刺激敏感聚合物对其环境的轻微变化有显着的反应。不同类型的刺激可影响聚合物的性能，其中最重要的是温度和 pH 值，因为这是人体的两个重要因素；因此，温度敏感和pH敏感的水凝胶已被广泛研究。水凝胶吸水和膨胀的能力归因于水凝胶网络中的亲水链，并且水凝胶的吸水性可以通过对刺激的响应来控制。由于水凝胶模仿人体组织，因此保留水分的能力至关重要。因此，许多生物医学药物输送系统都考虑它。刺激响应性膨胀可以控制水凝胶网络的扩散出入，从而可以控制药物释放的时间和空间。当药物负载到可生物降解且刺激敏感的水凝胶上时，药物输送系统具有药物持续释放的额外优势，从而减少副作用。方法：在本研究中，将两种不同的碳氢化合物，作为短链碳氢化合物的[1,3-二氨基丙烷（DAP）]和作为长链碳氢化合物的[1,7-二氨基庚烷（DAH）]接枝到三种类型的钠上海藻酸盐（SA），通过酰胺键连接。将水凝胶共聚物基质与海藻酸钠 (SA) 珠进行比较。使用 FTIR、1HNMR、XRD 光谱、元素分析 (CHNS) 和热分析（TGA、DTA 和 DSC）对接枝共聚物进行了表征。使用环境扫描电子显微镜（ESEM）研究水凝胶的表面形态。结果：与海藻酸盐交联的烃链长度、温度、pH 值和交联剂等变量对水凝胶性能的影响，在 2-70 ℃ 温度范围和两种不同 pH 值（4.4 和7.4）。结果表明，当二胺的烃链长度减小时，水凝胶的交联程度和强度增加。其他结果表明，从高粘度藻酸盐衍生物获得的水凝胶具有正 pH 敏感性。本研究中制备的水凝胶表现出良好的机械和溶胀比，这是伤口敷料所必需的。结论：通过酰胺键连接成功合成了DAP-g-SA和DAH-g-SA pH敏感水凝胶。新的合成衍生物在低 pH (4.4) 下表现出较低的溶胀水平。相比之下，它们在较高 pH (7.4) 下的溶胀水平显着增强。在高pH值下可获得较高的溶胀度。pH响应性水凝胶由于其网络结构中的受控膨胀、生物降解性、生物相容性和流体保留的独特特征而特别适用于各种生物应用。pH响应水凝胶作为智能系统，可用于控释药物递送系统，例如胰岛素递送。