Stimuli-responsive domains capable of releasing loaded molecules, “on-demand,” have garnered increasing attention due to their enhanced delivery, precision targeting, and decreased adverse effects. The development of an on-demand delivery system that can be easily triggered by dental clinicians might have major roles in dental and oral tissue engineering. A series of random graft poly(NIPAm-co-HEMA-Lactate) copolymers were synthesized using 95:5, 85:5, 60:40, and 40:60 ratios of thermosensitive NIPAm and HEMA-poly lactate respectively then electrospun to produce nanofibrous scaffolds loaded with bovine serum albumin (BSA). Cumulative BSA release was assessed at 25C and 37°C. To appraise the use of scaffolds as on-demand delivery systems, they were subjected to thermal changes in the form cooling and warming cycles during which BSA release was monitored. To confirm the triggered releasing ability of the synthesized scaffolds, the copolymer made with 60% NIPAm was selected, based on the results of the release tests, and loaded with bone morphogenetic protein-2 (BMP-2). The loaded scaffolds were placed with mesenchymal-like stem cells (iMSCs) derived from induced pluripotent stem cells (iPSCs), and subjected to temperature alterations. Then, the osteogenic differentiation of iMSCs, which might have resulted from the released protein, was evaluated after 10 days by analyzing runt-related transcription factor 2 (RUNX-2) osteogenic gene expression by the cells using real-time quantitative polymerase chain reaction (qRT-PCR). BSA release profiles showed a burst release at the beginning followed by a more linear pattern at 25°C, and a much slower release at 37°C. The release also decreased when the PNIPAm content decreased in the scaffolds. Thermal triggering led to a step-like release pattern in which the highest release was reported 30 min through the warming cycles. The iMSCs cultivated with scaffolds loaded with BMP-2 and exposed to temperature alteration showed significantly higher RUNX-2 gene expression than cells in the other experimental groups. The synthesized scaffolds are thermo-responsive and could be triggered to deliver biological biomolecules to be used in oral and dental tissue engineering. Thermal stimuli could be simulated by dental clinicians using simple means of cold therapy, for example, cold packs in intraoral accessible sites for specified times.

中文翻译：

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基于聚（N-异丙基丙烯酰胺）的智能纳米纤维支架，用作口腔和牙科组织再生的按需输送系统

能够“按需”释放负载分子的刺激响应域由于其增强的递送能力、精确的靶向性和减少的副作用而受到越来越多的关注。牙科临床医生可以轻松触发的按需输送系统的开发可能在牙科和口腔组织工程中发挥重要作用。分别使用 95:5、85:5、60:40 和 40:60 比例的热敏 NIPAm 和 HEMA-聚乳酸合成了一系列无规接枝聚 (NIPAm-co-HEMA-乳酸) 共聚物，然后静电纺丝生产纳米纤维。支架上装有牛血清白蛋白（BSA）。在 25°C 和 37°C 下评估累积 BSA 释放。为了评估支架作为按需输送系统的使用情况，他们在冷却和升温循环中经历了热变化，在此期间监测了 BSA 的释放。为了确认合成支架的触发释放能力，根据释放测试的结果，选择由 60% NIPAm 制成的共聚物，并负载骨形态发生蛋白 2 (BMP-2)。负载的支架上放置有源自诱导多能干细胞（iPSC）的间充质样干细胞（iMSC），并进行温度变化。然后，10天后，通过使用实时定量聚合酶链反应分析细胞的runt相关转录因子2（RUNX-2）成骨基因表达，评估iMSCs的成骨分化，这可能是由释放的蛋白质引起的。定量RT-PCR）。 BSA 释放曲线显示，开始时呈爆发式释放，随后在 25°C 时呈线性模式，在 37°C 时释放速度慢得多。当支架中 PNIPAm 含量减少时，释放也减少。热触发导致阶梯式释放模式，其中在升温周期的 30 分钟内报告最高释放量。使用装载有 BMP-2 的支架培养并暴露于温度变化的 iMSC 表现出比其他实验组中的细胞显着更高的 RUNX-2 基因表达。合成的支架具有热响应性，可以被触发以输送生物分子，用于口腔和牙科组织工程。牙科临床医生可以使用简单的冷疗方法来模拟热刺激，例如在口腔内可触及的部位进行指定时间的冷敷。