Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, IL 60616, USA.
J Fluoresc. 2012 May;22(3):907-13. doi: 10.1007/s10895-011-1029-6. Epub 2012 Jan 5.
Poly (ethylene glycol)-co-(L-Lactic acid) diacrylate (PEG-PLLA-DA) copolymers have been extensively investigated for a number of applications in medicine. PEG-PLLA-DA is biodegradable and the human body can process its degradation products. In this study, we describe the autofluorescence of PEG-PLLA-DA copolymers and compared it to the fluorescence of poly(ethylene glycol) diacrylate (PEG-DA) and the precursor molecules used for their synthesis. In addition, we examined the influence of pH on the fluorescence spectra. We found that PEG-PLLA-DA exhibits higher fluorescence than PEG-DA and all reagents involved in the synthesis of PEG-PLLA-DA. The fluorescence of PEG-PLLA-DA was affected by pH with fluorescence decreasing at high pH values. At high pH, PEG-PLLA-DA could not polymerize into hydrogels and exhibited a dramatic decrease in autofluorescence, suggesting that hydrolysis of the ester bond affected its autofluorescence. At low pH, PEG-PLLA-DA exhibited higher fluorescence and it was able to form crosslinked hydrogels. The autofluorescence of PEG-PLLA-DA could be exploited to monitor polymer degradation and material structure without the need to introduce exogenous fluorescent probes. The origin of fluorescence is not clear at this point in time but it appears to result from a synergetic effect of both lactate units and diacrylate groups in the PEG-PLLA-DA backbone. The observed autofluorescence of PEG-PLLA-DA persists after reaction of the acrylate groups in the polymerization reaction. This autofluorescence is advantageous because it could assist in the study of polymers used for drug delivery and tissue engineering applications.
聚乙二醇-co-(L-丙交酯)二丙烯酸酯（PEG-PLLA-DA）共聚物因其在医学领域的广泛应用而受到广泛研究。PEG-PLLA-DA 可生物降解，人体可以处理其降解产物。在这项研究中，我们描述了 PEG-PLLA-DA 共聚物的自发荧光，并将其与聚乙二醇二丙烯酸酯（PEG-DA）和用于其合成的前体分子的荧光进行了比较。此外，我们还研究了 pH 值对荧光光谱的影响。我们发现 PEG-PLLA-DA 的荧光强度高于 PEG-DA 和 PEG-PLLA-DA 合成中涉及的所有试剂。PEG-PLLA-DA 的荧光受 pH 值影响，在高 pH 值下荧光强度降低。在高 pH 值下，PEG-PLLA-DA 不能聚合形成水凝胶，并且自发荧光显著降低，表明酯键的水解影响了其自发荧光。在低 pH 值下，PEG-PLLA-DA 表现出更高的荧光强度，并且能够形成交联水凝胶。PEG-PLLA-DA 的自发荧光可用于监测聚合物降解和材料结构，而无需引入外源性荧光探针。目前尚不清楚荧光的起源，但它似乎是由 PEG-PLLA-DA 主链中乳酸单元和二丙烯酸酯基团的协同作用产生的。在聚合反应中丙烯酰基反应后，PEG-PLLA-DA 的自发荧光仍然存在。这种自发荧光是有利的，因为它可以帮助研究用于药物输送和组织工程应用的聚合物。
