Fluorescence imaging enabled urethane-doped citrate-based biodegradable elastomers

Abstract

The field of tissue engineering and drug delivery calls for new measurement tools, non-invasive real-time assays, and design methods for the next wave of innovations. Based on our recent progress in developing intrinsically biodegradable photoluminescent polymers (BPLPs) without conjugating organic dyes or quantum dots, in this paper, we developed a new type urethane-doped biodegradable photoluminescent polymers (UBPLPs) that could potentially serve as a new tool to respond the above call for innovations. Inherited from BPLPs, UBPLPs demonstrated strong inherent photoluminescence and excellent cytocompatibility in vitro. Crosslinked UBPLPs (CUBPLPs) showed soft, elastic, but strong mechanical properties with a tensile strength as high as 49.41±6.17 MPa and a corresponding elongation at break of 334.87±26.31%. Porous triphasic CUBPLP vascular scaffolds showed a burst pressure of 769.33±70.88 mmHg and a suture retention strength of 1.79±0.11 N. Stable but photoluminescent nanoparticles with average size of 103 nm were also obtained by nanoprecipitation. High loading efficiency (91.84%) and sustained release of 5-fluorouracil (up to 120 h) were achieved from UBPLP nanoparticles. With a quantum yield as high as 38.65%, both triphasic scaffold and nanoparticle solutions could be non-invasively detected in vivo. UBPLPs represent an innovation in fluorescent biomaterial design and may offer great potential in advancing the field of tissue engineering and drug delivery where bioimaging has gained increasing interest.

Synthesis and characterization of citrate-based fluorescent small molecules and biodegradable polymers

“…Previously, our group has demonstrated the applications of BPLPs in tissue engineering, bioimaging, theranostic drug delivery, and more recently, selective halide (chloride, bromide, iodide) sensing for fluorescence based diagnosis of cystic fibrosis 7, 14, 37, 38 . To establish that the TPA structure is indeed the fluorescent moiety of BPLPs, we synthesized polymers by reacting purified CA-Cys with 1,8-octanediol.…”

Citrate-Based Biomaterials and Their Applications in Regenerative Engineering

“…Hydrophilic fluorescent materials have also been designed by partially or fully replacing hydrophobic diols with PEG to produce hydrophilic BPLPs, which were then used to create amphiphilic copolymers for self-assembling micelles for potential use in theranostic applications (63, 64). Unsaturated functional groups have also been incorporated into BPLP design to cross-link the polymer network using free radical polymerization for injectable, minimally invasive applications, and urethane bonds have been introduced in the polymer network to dramatically increase the strength of the resulting elastomer (63, 65). …”

Click Chemistry Plays a Dual Role in Biodegradable Polymer Design

“…Pore sizes of 150–250 μm have been proven to be ideal for the growth of fibroblasts and SMCs and the formation of extracellular matrix (ECM). [3, 30] The photographs and representative SEM images of POC-click TBS shown in Figure 2B clearly imply the soft nature of the biphasic scaffold. Although molded into a porous scaffold, the tensile strength and Young’s modulus of POC-click TBS (around 5 and 17 MPa, respectively) are all much higher than that of POC TBS (~1 and 1.2 MPa respectively), and even higher than that of CUPE TBS (~3.8 and 4 MPa, respectively) (Figure 2C).…”