Dopamine-Initiated Photopolymerization for a Versatile Catechol-Functionalized Hydrogel

Abstract

Biomimetic catechol-functionalized hydrogels have attracted substantial attention due to their potential in a variety of biomedical applications, such as tissue repair and regeneration, drug delivery, and antimicrobial and antifouling applications. In this study, a one-pot strategy for fabrication of functional catecholic hydrogels using dopamine as a photoinitiator was developed. Under UV irradiation in an acidic solution, dopamine generates free radicals, likely semiquinone radicals, to trigger the addition polymerization, following pseudo-first-order kinetics. The dopamine-initiated photopolymerization provides a straightforward and facile approach and, in addition, prevents the undesirable oxidation to catecholic groups. Superhydrophilic sulfobetaine methacrylate (SBMA) was applied for developing biocompatible hydrogels. 1H nuclear magnetic resonance, UV–vis spectroscopy, gel permeation chromatography, and rheological studies were conducted to explore the polymerization mechanism and optimal experimental conditions in terms of pH, UV doses, and the concentration of dopamine. The unique properties of the resultant catechol-functionalized pSBMA hydrogels were demonstrated by enhanced mechanical properties through metal–catechol complexation, self-healing and injectable capability, high adhesiveness, and fouling resistance. Consequently, the synthetic strategy to design catecholic hydrogels can leverage the use of dopamine in a variety of applications.

Polymer Grafting to Polydopamine Free Radicals for Universal Surface Functionalization

“…The CCR formed during the oxidative polymerization of dopamine has been suggested to be capable of initiating FRP for generating PDA–polymer hydrogels; however, the specific initiating species and the underlying polymerization mechanism have yet to be understood. − PDA itself can also initiate FRP when illuminated under high-intensity UV irradiation (>100 mW/cm 2 ), where polymer brushes are proposed to grow from PDA-functionalized surfaces . In contrast to this, PDA has been employed to inhibit free radical formation in polymer formulations, reducing the radical-induced thermal and photo-degradation of polymer materials. , The SQR of PDA has been shown to contribute to the widely reported free radical scavenging of these materials .…”

A Multicomponent Polymer-Metal-Enzyme System as Electrochemical Biosensor for H2O2 Detection

“…The spectrum of PAA-graphene presents a maximum absorption at 263 nm, which signifies π-π* transitions between the aromatic C=C bonds (He et al, 2011). After reacting with DA, a shoulder peak at 275 nm, a characteristic absorption for catechol, is detected (Bui et al, 2021). After reduction of HAuCl 4 , a relatively new peak at 556 nm appears and the solution becomes violet black in color.…”

Green Hydrogel Synthesis: Emphasis on Proteomics and Polymer Particle-Protein Interaction

“…As a more biocompatible alternative to the Irgacure 2959 photoinitiator, Bui et al synthesized a catechol-functionalized hydrogel using dopamine as a photoinitiator to polymerize sulfobetaine methacrylate and BIS in Tris buffer. Dopamine exhibited lower cytotoxicity than Irgacure 2959 and yielded a self-healing, injectable hydrogel [ 168 ]. In an innovative green chemistry approach, Fonseca et al synthesized hydrogels from milk permeate, an agriculture industry waste product, by functionalizing lactose with methacrylic anhydride via ester linkage prior to aqueous UV photopolymerization without requiring a photoinitiator [ 169 ].…”