Dopant‐Free Hydrogels with Intrinsic Photoluminescence and Biodegradable Properties

Abstract

Photoluminescent hydrogels that function as both injectable scaffolds and fluorescent imaging probes hold great potential for therapeutics delivery and tissue engineering. Current fluorescent hydrogels are fabricated by either conjugating or doping a fluorescent dye, fluorescent protein, lanthanide chelate, or quantum dot into polymeric hydrogel matrix. Their biomedical applications are severely limited due to drawbacks such as photostability, carcinogenesis, and toxicity associated with the above-mentioned dopants. Here, a successful development of dopant-free photoluminescent hydrogels in situ formed by crosslinking of biocompatible polymer precursors is reported, which can be synthesized by incorporating an amino acid to a citric acid based polyester oligomer followed by functionalization of multivalent crosslinking group through a convenient transesterification reaction using Candida Antarctica Lipase B as a catalyst. It is demonstrated that the newly developed hydrogels possess tunable degradation, intrinsic photoluminescence, mechanical properties, and exhibit sustained release of various molecular weight dextrans. In vivo study shows that the hydrogels formed in situ following subcutaneous injection exhibit excellent biocompatibility and emit strong fluorescence under visible light excitation without the need of using any traditional organic dyes. Their in vivo degradation profiles are then depicted by noninvasively monitoring fluorescence intensity of the injected hydrogel implants.

Roles and Mechanisms of Irisin in Attenuating Pathological Features of Osteoarthritis

“…Then we performed intraarticular injection of r-IRS protein with a nano-hydrogel. The hydrogel possesses ideal biocompatibility, biodegradability, tunable stiffness, intrinsic photoluminescence and injectable properties ( Tsou et al, 2018 ). Besides, the hydrogel has an excellent r-IRS protein release characteristic ( Figure 5C ) and can be detected under 360 UV light both in vitro ( Figure 5A ) and in vivo ( Figure 5B ).…”

“…The DMM surgery were completed on the right knee. The polyester-based hydrogel was synthesized following previously published procedures ( Tsou et al, 2018 ) with minor modifications. Briefly, the CHPO-Ser-ET oligomer was synthesized via polycondensation reaction between citric acid, serine and hexaethylene glycol.…”

“…Briefly, the IRS-loaded hydrogel was immersed in PBS. The suspension liquid was collected and analyzed for the release study using ELISA following the methods established in our lab and others that are designed specifically for IRS analysis ( Efe et al, 2017 ; Tsou et al, 2018 ; Yuan et al, 2019 ). At 2 days post-OA surgery, the hydrogel (10 wt%, 1XPBS, pH = 7.4, 1 μg/μl IRS) was injected into the knee joints of KO mice by a trans-patellar tendon approach every 3-days in the laboratory.…”

Multicolor Fluorescent Polymeric Hydrogels

“…In the area of in vivo detecting and tracking, Xu and co‐workers have developed an injectable and biocompatible MFPH‐based imaging probe (Figure 9 C). [37a] Although no traditional organic dyes are used, the system still emits strong fluorescence under irradiation with UV light. This hydrogel probe was further demonstrated to have tunable degradation and mechanical properties, as well as the ability to gel in situ after injection.…”

Biocompatible and Biodegradable Light‐Emitting Materials and Devices

“…b) (Left) Images of CHPO-Ser-ET/eight-arm PEG-maleimide hydrogels under ambient light (top) and with excitation at 450 nm (bottom), and (middle and right) corresponding PL spectra emission spectra at excitations of 365 nm (middle) and 488 nm (right). Reproduced with permission [18]. Copyright 2018, Wiley-VCH.…”