Photocurable Thiol–yne Alginate Hydrogels for Regenerative Medicine Purposes

Abstract

Every year millions of people worldwide undergo surgical interventions, with the occurrence of mild or severe post-treatment consequences meaning that rehabilitation plays a key role in modern medicine. Considering the cases of burns and plastic surgery, the pressing need for new materials that can be used for wound patches or body fillers and are able to sustain tissue regeneration and promote cell adhesion and proliferation is clear. The challenges facing next-generation implant materials also include the need for improved structural properties for cellular organization and morphogenic guidance together with optimal mechanical, rheological, and topographical behavior. Herein, we propose for the first time a sodium alginate hydrogel obtained by a thiol–yne reaction, easily synthesized using carbodiimide chemistry in a two-step reaction. The hydrogels were formed in all cases within a few minutes of light irradiation, showing good self-standing properties under solicitation. The mechanical, rheological, topographical, and swelling properties of the gels were also tested and reported. Lastly, no cytotoxicity was detected among the hydrogels. Soluble extracts in culture media allowed cell proliferation, and no differences between samples were detected in terms of metabolic activity and DNA content. These results suggest the potential use of these cytocompatible hydrogels in tissue engineering and regenerative medicine.

Solid Rocket Propellant Photo-Polymerization with an In-House LED-UV Prototype

“…Lately, photo-polymerization processes have been proposed as a suitable alternative to standard production techniques in many different fields such as: coatings [ 12 , 13 ], composites [ 14 ], microelectronics [ 15 ], medicine [ 16 ], additive manufacturing [ 17 , 18 , 19 ] and more recently also in the energetic material production [ 20 , 21 , 22 ]. In particular, in the energetic material production, UV-curing technique seems to find its best fallout on optimization of charge grain production, overcoming shaping issues, and avoiding extra tooling costs, as enabler of additive manufacturing in this specific field.…”

Vat 3D printing of full-alginate hydrogels via thiol–ene reactions towards tissue engineering applications

“…This system possesses a yield point at 138% of strain, which is in line or higher with respect to other polysaccharide-based crosslinked hydrogels. 31,35,69,71,72 Furthermore, the compressive elastic modulus of 44 ± 3 kPa places the resulting hydrogel among the stiff soft tissue scaffolds, with properties comparable with the human intestine or tendons (Fig. 4C).…”

“…Strictly concerning alginate photocrosslinking, to the best of our knowledge, just a few publications focused on the creation of photocured thiol–ene/yne alginate hydrogels are available and these report the use of ene/yne-modified alginate crosslinked with the addition of synthetic dithiol molecules. 31,35…”

“…[30][31][32] Under these circumstances, especially "click chemistry" reactions are employed because of their rapidity, versatility, regiospecificity, easy usability, and high yields achievable under mild conditions. [33][34][35] Despite the fact that thiol-ene reactions are known to be biocompatible photoinduced reactions, [36][37][38] thiomers have gained increased popularity in the last decade in the biomedical field mainly for drug delivery applications (due to their mucoadhesive properties) [39][40][41] but not much for tissue engineering applications. [42][43][44] Within this framework, many synthetic protocols have been reported in the last few years to functionalize alginate with thiol moieties, [45][46][47] but not much attention has been paid to the maximization of the degree of functionalization (essential if pursuing a photoactivated crosslinking via thiol-ene reactions, also suitable for DLP printing).…”

“…Strictly concerning alginate photocrosslinking, to the best of our knowledge, just a few publications focused on the creation of photocured thiol-ene/yne alginate hydrogels are available and these report the use of ene/yne-modified alginate crosslinked with the addition of synthetic dithiol molecules. 31,35 Herein, aiming to enlarge the palette of 3D printable hydrogels, sodium alginate was selected considering its easy modification due to its high quantity of carboxylic moieties (compared with chitosan, hyaluronic acid, cellulose, etc.). 48 Different polysaccharide batches were modified separately with alkene and thiol groups investigating different functionalization procedures and different degrees of functionalization toward the creation of hydrogels.…”