透過交聯劑設計調控幾丁聚醣/葡聚醣水凝膠的結構與性質於感測應用

Abstract

交聯劑在水凝膠的製備及網絡結構和特性等方面至關重要，在親水高分子中引入疏水片段會引起微相分離，從而顯著提高水凝膠的機械拉伸性。透過調整這些疏水鏈段的長度，可以調整水凝膠的彈性和延展性。在本研究中，我們利用不同疏水鏈長的二羧酸（即己二酸 (AA)、癸二酸 (SA) 和十四烷二酸 (TDA)）合成功能性交聯劑，並透過帕瑟里尼反應與醛官能化的聚乙二醇 (PEG-FA) 反應，得到三種含醛的交聯劑（即 AA-PEG-FA, SA-PEG-FA, and TDA-PEG-FA）。隨後將這些交聯劑與季銨化幾丁聚醣 (QCS) 和葡聚醣肼 (PDH) 結合，並透過動態鍵（例如靜電相互作用、氫鍵、亞胺鍵和腙鍵）形成 QCS/PDH 水凝膠。結果表明，交聯劑的疏水鏈段越長，水凝膠的拉伸應變就越大。因此，可以透過交聯劑的長短來微調 QCS/PDH 水凝膠的機械特性，以滿足生物醫學工程、穿戴式裝置和其他先進材料應用的需求。 此外，我們期望透過共價鍵形成的網絡結構來提升水凝膠的抗壓強度，我們使用由聚丙烯醯胺（PAM）與TDA-PEG-FA形成的互穿高分子網絡（IPN）水凝膠。為了進一步增強其功能性，我們在水凝膠中引入了銪離子。銪離子的加入不僅能強化水凝膠的網絡結構，還使其具有發光特性。藉由這些特性，該水凝膠未來有望應用於即時監測與先進感測等領域。

It has been well-documented that crosslinkers play a crucial role in determining the structures and properties of hydrogel networks. Introducing hydrophobic segments in hydrophilic polymers induces microphase separation, significantly improving the mechanical stretchability of the hydrogel matrix. By adjusting the length of these hydrophobic segments, one can tailor the elasticity and extendibility of the hydrogels. In this study, we synthesized functional crosslinkers using dicarboxylic acids with different hydrophobic chain lengths (i.e., adipic acid (AA), sebacic acid (SA), and tetradecanedioic acid (TDA)), which were reacted with aldehyde-functionalized polyethylene glycol (PEG-FA) via the Passerini reaction, yielding three types of aldehyde-containing crosslinkers (i.e., AA-PEG-FA, SA-PEG-FA, and TDA-PEG-FA). These crosslinkers were subsequently incorporated with quaternized chitosan (QCS) and polydextran hydrazide (PDH) to form hybrid QCS/PDH hydrogels through dynamic bonds (e.g., electrostatic interactions, hydrogen bonding, imine bonds, and hydrazone bonds). The results showed that the tensile strains of hydrogels increased with crosslinkers with longer hydrophobic chain segments. Therefore, the mechanical characteristics of QCS/PDH hydrogels can be fine-tuned through crosslinker design, addressing requirements across biomedical engineering, wearable devices, and other advanced material applications. Besides, we aim to construct a covalent bond-formed network to allow the hydrogel with enhanced mechanical strength by developing an interpenetrating polymer network (IPN) hydrogel with polyacrylamide (PAM) and TDA-PEG-FA. To enhance the functionality, trivalent europium (Eu3+) was incorporated into the hydrogel. The addition of Eu³⁺ not only strengthens the hydrogel network but also enables luminescence. With these features, the hydrogel may be used in real-time monitoring and advanced sensing applications.