In Vitro Investigation of Thiol-Functionalized Cellulose Nanofibrils as a Chronic Wound Environment Modulator

Abstract

There is currently a huge need for new, improved therapeutic approaches for the treatment of chronic wounds. One promising strategy is to develop wound dressings capable of modulating the chronic wound environment (e.g., by controlling the high levels of reactive oxygen species (ROS) and proteases). Here, we selected the thiol-containing amino acid cysteine to endow wood-derived cellulose nanofibrils (CNF) with bioactivity toward the modulation of ROS levels and protease activity. Cysteine was covalently incorporated into CNF and the functionalized material, herein referred as cys-CNF, was characterized in terms of chemical structure, degree of substitution, radical scavenging capacity, and inhibition of protease activity. The stability of the thiol groups was evaluated over time, and an in vitro cytotoxicity study with human dermal fibroblasts was performed to evaluate the safety profile of cys-CNF. Results showed that cys-CNF was able to efficiently control the activity of the metalloprotease collagenase and to inhibit the free radical DPPH (1,1-Diphenyl-2-picrylhydrazyl radical), activities that were correlated with the presence of free thiol groups on the nanofibers. The stability study showed that the reactivity of the thiol groups challenged the bioactivity over time. Nevertheless, preparing the material as an aerogel and storing it in an inert atmosphere were shown to be valid approaches to increase the stability of the thiol groups in cys-CNF. No signs of toxicity were observed on the dermal fibroblasts when exposed to cys-CNF (concentration range 0.1–0.5 mg/mL). The present work highlights cys-CNF as a promising novel material for the development of bioactive wound dressings for the treatment of chronic wounds.

Near-infrared analysis of nanofibrillated cellulose aerogel manufacturing

“…In general, aerogels are solid lightweight materials with extremely low density in between 0.001 and 0.2 g/cm 3 , with over 90% porosity with the most prevalent pore diameter of 2-50 nm and with tunable mechanical and chemical properties (Zaman et al, 2020). Concerning the drug delivery and biomedical approaches, aerogels can be utilized for example for controlled drug release, to provide scaffolds for cell colonization, or wound healing (Blasi-Romero et al, 2021;Grenier et al, 2019;Nagy et al, 2019).…”

Approaches to Control and Monitor Protease Levels in Chronic Wounds

“…Blasi‐Romero and others prepared cysteine‐conjugated cellulose nanofibrils; they reported that collagenase activity was reduced in a dose‐dependent manner, primarily through inactivation rather than sequestration from protease solution. [ 163 ] This effect was assigned to the modification with thiol groups.…”

Thiolated Poly‐ and Oligosaccharide‐Based Hydrogels for Tissue Engineering and Wound Healing

“…The findings of this research underscore the potential of cysteine-modified cellulose nanofibrils as a promising material for the development of bioactive wound dressings, particularly for the treatment of chronic wounds. [175] Xu et al synthesized a hydrogel through the reaction between sodium alginate and cysteine methyl ester, leading to the formation of thiolated alginate (SA-SH). The thiolated alginate rapidly underwent in situ gelation (SA-SS-SA) by covalent bonding within a short span of 20 seconds, resulting in a highly hydrated hydrogel structure.…”

“…Moreover, the strong intermolecular interactions between thiolated polymers and blood cells, resulting from the electrostatic attraction between cationic polymers (positively charged) and negatively charged blood cells, contribute to their high hemostatic properties. [ 35,175 ] The mechanism underlying the effectiveness of hydrogels as wound dressings can be attributed to their unique properties. Specifically, hydrogels possess the capacity to absorb and retain wound exudates, thereby creating a conducive environment for critical biological events such as fibroblast proliferation and keratinocyte migration.…”