School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, BT9 7BL, United Kingdom.
School of Mechanical and Aerospace Engineering, Queen's University Belfast, 123 Stranmillis Road, Belfast BT9 5AH, United Kingdom.
Mater Sci Eng C Mater Biol Appl. 2019 Feb 1;95:409-421. doi: 10.1016/j.msec.2017.09.003. Epub 2017 Sep 27.
Alginate grafted poly(N-isopropylacrylamide) hydrogels (Alg-g-P(NIPAAm)) form three-dimensional networks in mild conditions, making them suitable for incorporation of labile macromolecules, such as DNA. The impact of P(NIPAAm) on copolymer characteristics has been well studied, however the impact of alginate backbone characteristics on copolymer properties has to-date not been investigated. Six different Alg-g-P(NIPAAm) hydrogels were synthesised with 10% alginate, which varied in terms of molecular weight (MW) and mannuronate/guluronate (M/G) monomer ratio, and with 90% NIPAAm in order to develop an injectable and thermo-responsive hydrogel formulation for localised gene delivery. Hydrogel stiffness was directly proportional to MW and the M/G ratio of the alginate backbone. Hydrogels with a high MW or low M/G ratio alginate backbone demonstrated a greater stiffness than those hydrogels comprising low MW alginates and high M/G ratio. Hydrogels with a high M/G ratio also produced a complexed and meshed hydrogel network while hydrogels with a low M/G ratio produced a simplified structure with the superposition of Alg-g-P(NIPAAm) sheets. This study was designed to produce the optimal Alg-g-P(NIPAAm) hydrogel with respect to localised delivery of DNA nanoparticles as a potential medical device for those with castrate resistant prostate cancer (CRPC). Given that CRPC typically disseminates to bone causing pain, morbidity and a plethora of skeletal related events, a copolymer based hydrogel was designed to for long term release of therapeutic DNA nanoparticles. The nanoparticles were comprised of plasmid DNA (pDNA), complexed with an amphipathic cell penetrating peptide termed RALA that is designed to enter cells with high efficiency. Alginate MW and M/G ratio affected stiffness, structure, injectability and degradation of the Alg-g-P(NIPAAm) hydrogel. Algogel 3001, had the optimal characteristics for long-term application and was loaded with RALA/pDNA NPs. From the release profiles, it was evident that RALA protected the pDNA from degradation over a 30-day period and conferred a sustained and controlled release profile from the hydrogels compared to pDNA only. Taken together, we have designed a slowly degrading hydrogel suitable for sustained delivery of nucleic acids when incorporated with the RALA delivery peptide. This now opens up several opportunities for the delivery of therapeutic pDNA from this thermo-responsive hydrogel with numerous medical applications.
藻酸盐接枝聚（N-异丙基丙烯酰胺）水凝胶（Alg-g-P（NIPAAm））在温和条件下形成三维网络，使其适合掺入不稳定的大分子，如 DNA。聚（N-异丙基丙烯酰胺）对共聚物特性的影响已经得到了很好的研究，然而，藻酸盐主链特性对共聚物性质的影响迄今为止尚未得到研究。用 10%的藻酸盐合成了六种不同的 Alg-g-P（NIPAAm）水凝胶，其分子量（MW）和甘露糖醛酸/古洛糖醛酸（M/G）单体比不同，并含有 90%的 NIPAAm，以便开发一种可注射和温敏水凝胶制剂，用于局部基因传递。水凝胶的硬度与 MW 和藻酸盐主链的 M/G 比直接成正比。具有高分子量或低 M/G 比藻酸盐主链的水凝胶表现出比那些由低分子量藻酸盐和高 M/G 比组成的水凝胶更高的硬度。具有高 M/G 比的水凝胶还产生了复杂的网状水凝胶网络，而具有低 M/G 比的水凝胶则产生了具有 Alg-g-P（NIPAAm）片层叠加的简化结构。这项研究旨在生产出最佳的 Alg-g-P（NIPAAm）水凝胶，以实现 DNA 纳米颗粒的局部传递，作为治疗去势抵抗性前列腺癌（CRPC）的潜在医疗器械。鉴于 CRPC 通常扩散到骨骼引起疼痛、发病率和大量骨骼相关事件，设计了一种基于共聚物的水凝胶，用于长期释放治疗性 DNA 纳米颗粒。纳米颗粒由质粒 DNA（pDNA）组成，与一种称为 RALA 的两亲性细胞穿透肽复合，旨在高效进入细胞。藻酸盐 MW 和 M/G 比对 Alg-g-P（NIPAAm）水凝胶的硬度、结构、可注射性和降解性有影响。Algogel 3001 具有长期应用的最佳特性，并负载了 RALA/pDNA NPs。从释放曲线可以明显看出，与仅 pDNA 相比，RALA 保护了 pDNA 在 30 天内免受降解，并赋予了水凝胶的持续和控制释放曲线。总之，我们设计了一种缓慢降解的水凝胶，当与 RALA 递药肽结合时，适合于核酸的持续递药。这为从这种温敏水凝胶中递送电疗性 pDNA 提供了多种医疗应用机会。
