Thiolated polymeric hydrogels for biomedical application: Cross-linking mechanisms

Thiolated-Polymer-Based Nanoparticles as an Avant-Garde Approach for Anticancer Therapies—Reviewing Thiomers from Chitosan and Hyaluronic Acid

“…Photo-initiated thiol-ene reactions are frequently used for the synthesis of hydrogel networks in the biomedical field [77]. Another interesting nucleophilic reaction in which thiol groups participate is the Michael addition, commonly used to crosslink thiomers to improve the mechanical properties of, for example, 3D scaffolds and hydrogels [11,78,79]. It is also of interest in the anchoring of APIs to DDSs such as the monoclonal antibody Cetuximab [80].…”

“…The reaction is catalyzed by a nucleophile (Figure 7) that generates the thiolate anion, which is the nucleophilic species. R-S − will react with the β carbon from the α,β-unsaturated carbonyl moiety [11,15,78,79]. The catalysts are nucleophilic species such as amines [81] or alkylphosphines [82], which have been demonstrated to be extremely efficient in speeding up thiol-Michael addition reactions.…”

“…Thiolated polymers (thiomers) are biocompatible polymers that bear free or activated thiol groups covalently attached to them. They began to be explored in 1999 [10], and have since been used in multiple biomedical and pharmaceutical applications due to the close interest in their study among the research community [11][12][13]. These applications are connected with the presence of their thiol groups and their capability of conducting thiol-disulfide exchange reactions and oxidizing to disulfide bridges: from soft-tissue engineering [14] as biomaterial support for cartilage repair [15] and 3D bioscaffolds for cell culture [16,17] to antibacterial activity [18][19][20][21].…”

“…In tackling the preparation of new thiolated polymers, derivatization of (semi)natural polysaccharides is an interesting approach because of their inherent biocompatibility, degradability, absence of toxicity, and chemical versatility. Due to their unique properties, chitosan (CTS) and hyaluronic acid (HA) stand out among the most promising polysaccharides studied for biomedical applications [11][12][13]32], and more recently, their thiolated derivatives are gaining attention. In this review, we will focus on the thiolation strategies of the major biocompatible polysaccharides CTS and HA as promising platforms for the development of nanoparticulated DDS in anticancer therapy.…”

Thiomers of Chitosan and Cellulose: Effective Biosorbents for Detection, Removal and Recovery of Metal Ions from Aqueous Medium

“…There are several other factors that can reduce the efficiency of metal adsorbent of thiomers containing SH groups. It is well‐known that free thiol groups (SH) can oxidize and convert to disulfide (S−S) by oxygen in air [48,49] . This oxidation effectively is accelerated at higher pHs.…”