Sapkota Thakur, Shrestha Sita, Regmi Bishnu P, Bhattarai Narayan
Department of Applied Science and Technology, North Carolina A&T State University Greensboro NC 27411 USA.
Department of Chemical, Biological, and Bioengineering, North Carolina A&T State University Greensboro NC 27411 USA
RSC Adv. 2025 Apr 22;15(16):12876-12895. doi: 10.1039/d5ra01397f. eCollection 2025 Apr 16.
Nanofiber-embedded 3D hydrogel constructs have garnered significant attention due to their versatile applications in drug delivery, cell therapy, tissue engineering, and regenerative medicine. These constructs are especially prized for their capacity to mimic the composition of the extracellular matrix (ECM) found in living tissues and organs. The unique chemical and mechanical properties of hydrogel microcapsules have made them particularly notable among various biomaterial constructs for their effectiveness in cell encapsulation, which aims to improve cell growth and proliferation. In this study, we developed alginate hydrogel microcapsules embedded with chitin nanofibrils, using divalent calcium ions and trivalent iron ions as crosslinking agents. An electrostatic encapsulation technique was utilized to create microcapsules with diameters ranging from 200-500 μm, and their physicochemical properties, rheological properties, size, and mechanical stability were evaluated. The rheological analysis demonstrated that the Fe crosslinked hydrogel (AF0) and Fe/Ca cross-linked hydrogel (AFC) have higher storage modulus than the Ca crosslinked hydrogel (AC0). Additionally, FTIR analyses of AF0 and AFC demonstrated a broader -O-H stretching peak compared to that of AC0, suggesting that more hydroxyl groups of alginate chains are involved in crosslinking with ferric ions exhibiting extended mechanical stability compared to those crosslinked with calcium ions under physiological conditions. We also investigated the cellular responses to the composite hydrogels crosslinked with these divalent and trivalent metal ions through studies involving the seeding and encapsulation of NIH/3T3 fibroblast cells. Remarkably, both types of crosslinked microcapsules maintained excellent cell viability for up to 5 days. Our scratch assay demonstrated that media extracted from AF0 microcapsules facilitated faster wound closure compared to that extracted from AC0, suggesting that hydrogels crosslinked with Fe ions promote enhanced cellular proliferation. These results suggest that calcium and ferric ion crosslinked alginate-chitin composite microcapsules provide a promising platform for developing 3D hydrogel constructs suitable for various biomedical applications, including wound healing models, tissue engineering, and drug toxicity testing.
嵌入纳米纤维的3D水凝胶构建体因其在药物递送、细胞治疗、组织工程和再生医学中的广泛应用而备受关注。这些构建体因其能够模拟活组织和器官中细胞外基质（ECM）的组成而备受珍视。水凝胶微胶囊独特的化学和机械性能使其在各种生物材料构建体中脱颖而出，尤其在细胞封装方面表现出色，旨在促进细胞生长和增殖。在本研究中，我们以二价钙离子和三价铁离子作为交联剂，开发了嵌入几丁质纳米纤维的藻酸盐水凝胶微胶囊。利用静电封装技术制备了直径范围为200 - 500μm的微胶囊，并对其物理化学性质、流变学性质、尺寸和机械稳定性进行了评估。流变学分析表明，铁交联水凝胶（AF0）和铁/钙交联水凝胶（AFC）的储能模量高于钙交联水凝胶（AC0）。此外，AF0和AFC的傅里叶变换红外光谱（FTIR）分析显示，与AC0相比，其 -O-H 伸缩峰更宽，这表明藻酸盐链的更多羟基参与了与铁离子的交联，与在生理条件下与钙离子交联的情况相比，表现出更长的机械稳定性。我们还通过涉及NIH/3T3成纤维细胞接种和封装的研究，研究了细胞对与这些二价和三价金属离子交联的复合水凝胶的反应。值得注意的是，两种类型的交联微胶囊在长达5天的时间内都保持了优异的细胞活力。我们的划痕试验表明，与从AC0中提取的培养基相比，从AF0微胶囊中提取的培养基促进伤口闭合的速度更快，这表明与铁离子交联的水凝胶促进了细胞增殖增强。这些结果表明，钙和铁离子交联的藻酸盐 - 几丁质复合微胶囊为开发适用于各种生物医学应用的3D水凝胶构建体提供了一个有前景的平台，包括伤口愈合模型、组织工程和药物毒性测试。
