Sahiner Nurettin, Jha Amit K, Nguyen David, Jia Xinqiao
Department of Materials Science and Engineering, 201 DuPont Hall, University of Delaware, Newark, DE 19716, USA.
J Biomater Sci Polym Ed. 2008;19(2):223-43. doi: 10.1163/156856208783432462.
There is a critical need to engineer hyaluronic acid (HA)-based hydrogels with prolonged in vivo residence time, temporal release of therapeutics and matching viscoelasticity for use in vocal fold tissue engineering. We have previously demonstrated the synthesis and characterization of HA-based soft hydrogel particles (HGP) and particle cross-linked networks as injectable materials to treat vocal fold scarring. In this paper, we report a more versatile technique for preparing cross-linkable HA HGP with reduced sizes. HA HGP were synthesized via chemical cross-linking with divinyl sulfone using a sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane reverse micelle system in the presence of 1-heptanol. These HGP were rendered cross-linkable by introducing aldehyde groups via sodium periodate oxidation (oxHGP). The presence of aldehyde groups was confirmed by multi-photon confocal microscope upon fluorescence staining using cascade blue hydrazide. The aldehyde groups were used as reactive handles for covalent cross-linking with HA that has been previously modified with adipic acid dihydrazide (HADH). The resulting doubly cross-linked networks (DXN) are highly pliable and do not break until approx. 200-300% strain. The measured elastic modulus of the DXN is around 500 Pa, while the dynamic viscosity decreases linearly with frequency in log- log scale. The mechanical characteristics of DXN are similar to that of vocal fold lamina propria. In vitro cell-proliferation assays showed that the cross-linkable HA HGP did not adversely affect the proliferation of the cultured fibroblasts as assessed by MTT assay. A low-molecular-weight model drug, rhodamine 6G (R6G), was loaded into oxHGP, and its release was monitored using UV-Vis spectroscopy. R6G-loaded oxHGP maintained their ability to form DXN when mixed with the HAADH solution. Approximately 84% of entrapped R6G was liberated from oxHGP at a rate of 0.24%/min in the first 6 h. When encapsulated in the DXN, R6G was released at a steady rate of 0.03%/min for over 3 days. These novel hydrogels are promising implant materials for vocal fold tissue regeneration.
迫切需要设计出具有延长体内停留时间、治疗药物的定时释放以及匹配的粘弹性的基于透明质酸（HA）的水凝胶，用于声带组织工程。我们之前已经展示了基于HA的软水凝胶颗粒（HGP）和颗粒交联网络的合成与表征，它们作为可注射材料用于治疗声带瘢痕。在本文中，我们报道了一种制备尺寸更小的可交联HA HGP的更通用技术。HA HGP是在1 - 庚醇存在下，使用双（2 - 乙基己基）磺基琥珀酸钠（AOT）/异辛烷反胶束体系通过与二乙烯基砜化学交联合成的。通过高碘酸钠氧化（oxHGP）引入醛基使这些HGP具有可交联性。使用级联蓝酰肼进行荧光染色后，通过多光子共聚焦显微镜确认了醛基的存在。醛基用作与预先用己二酸二酰肼（HADH）修饰的HA进行共价交联的反应位点。所得的双交联网络（DXN）具有高度柔韧性，在约200 - 300%应变之前不会断裂。DXN的测量弹性模量约为500 Pa，而动态粘度在对数 - 对数尺度上随频率线性降低。DXN的力学特性与声带固有层相似。体外细胞增殖试验表明：通过MTT试验评估，可交联的HA HGP对培养的成纤维细胞的增殖没有不利影响。一种低分子量模型药物罗丹明6G（R6G）被载入oxHGP中，并使用紫外 - 可见光谱监测其释放。载入R6G的oxHGP与HAADH溶液混合时保持了形成DXN的能力。在前6小时内，约84%包封的R6G以0.24%/分钟的速率从oxHGP中释放出来。当封装在DXN中时，R6G以0.03%/分钟的稳定速率释放超过3天。这些新型水凝胶是用于声带组织再生的有前景的植入材料。
