Real-time and non-invasive fluorescence tracking of in vivo degradation of the thermosensitive PEGlyated polyester hydrogel†
The real-time monitoring of materials degradation is crucial to determine the in vivo retention time and the design or screening of degradable biomaterials. However, in vivo performance cannot always be predicted through the traditional determination of in vitro erosion and current standard methods sacrifice samples or animals, preventing the sequential measurement of the same specimen. Herein, a non-invasive fluorescence imaging method was developed to sequentially follow in vivo loss of fluorescence signal to simultaneously characterize the hydrolytic and enzymatic degradation of PEGlyated polyester hydrogel. Rhodamine B was conjugated to thermosensitive amphiphilic triblock copolymer based on cyclic ether modified PCL and PEG (abbreviated as PECT) and no obvious influence on gelation time or gel strength was observed with the conjugation content under 0.121% (w/w). Both in vitro and in vivo degradation profiles followed linear fittings while in vivo and in vitro hydrogel degradation rates correlated in an exponential mathematical model, enabling the general prediction of in vivo erosion trends of new biomaterial formulations from in vitro data. This methodology possibly enabled rational design and rapid in vitro screening of degradable materials, and might be potentially extended to simultaneously determine the material erosion and speculate the drug release from a drug-incorporated scaffold, or the cell growth profile in tissue-engineering formulations.