Amphiphilic Self-Assembled “Polymeric Drugs”: Morphology, Properties, and Biological Behavior of Nanoparticles

Bioactive and Bioadhesive Catechol Conjugated Polymers for Tissue Regeneration

The effective treatment of chronic wounds constitutes one of the most common worldwide healthcare problem due to the presence of high levels of proteases, free radicals and exudates in the wound, which constantly activate the inflammatory system, avoiding tissue regeneration. In this study, we describe a multifunctional bioactive and resorbable membrane with in-built antioxidant agent catechol for the continuous quenching of free radicals as well as to control inflammatory response, helping to promote the wound-healing process. This natural polyphenol (catechol) is the key molecule responsible for the mechanism of adhesion of mussels providing also the functionalized polymer with bioadhesion in the moist environment of the human body. To reach that goal, synthesized statistical copolymers of N-vinylcaprolactam (V) and 2-hydroxyethyl methacrylate (H) have been conjugated with catechol bearing hydrocaffeic acid (HCA) molecules with high yields. The system has demonstrated good biocompatibility, a sustained antioxidant response, an anti-inflammatory effect, an ultraviolet (UV) screen, and bioadhesion to porcine skin, all of these been key features in the wound-healing process. Therefore, these novel mussel-inspired materials have an enormous potential for application and can act very positively, favoring and promoting the healing effect in chronic wounds.

Soft amphiphilic polyesters obtained from PEGs and silicon fatty compounds: structural characterizations and self-assembly studies

Transesterification polymerizations between a silicon fatty ester derived from methyl 10-undecenoate and polyethylene glycol (PEG) monomers generate amphiphilic biopolyesters ​showing abilities to form micelle and fiber structures.

Amphiphilic polysaccharide nanocarriers with antioxidant properties

The development of self-assembled nanocarriers for the encapsulation of hydrophobic antioxidants is of growing interest. Self-assembled amphiphilic chitosan conjugate nanocarriers that stabilize antioxidants were prepared based on the concept that both the nanocarrier and the antioxidant bear similar hydrophobic moieties able to establish hydrophobic interactions. This work describes the preparation and characterization of a system consisting of a palmitoyl chitosan conjugate and retinyl palmitate. Palmitic acid was coupled to chitosan using a carbodiimide-mediated coupling reaction, and two different palmitoyl chitosan conjugates were obtained by varying the coupling system. Palmitoyl chitosan conjugates self-assembled to form nanoparticles in aqueous medium varying in mean average diameter (Dh) between 200 and 437 nm. Retinyl palmitate–loaded nanoparticles were prepared by a solvent displacement method using dialysis, with loading efficiencies of 77.5% and 88.6%, loading contents of 12.6% and 14.6%, and Dh values of approximately 280 nm. The zeta potential (ζ) of all palmitoyl chitosan nanoparticle were above 25 mV, but ζ slightly increased in the retinyl palmitate–loaded nanoparticle. Antioxidant activity of loaded nanoparticles was confirmed using the 1,1-diphenyl-2-picryl-hydrazyl radical scavenging assay. The in vitro cytotoxicity of blank and loaded nanoparticles was determined using fibroblasts of human embryonic skin. All nanoparticles were not cytotoxic when they were tested with methylthiazol tetrazolium and lactate dehydrogenase tests. The obtained results suggest that the system has potential as a nanocarrier for dermal application. Additionally, the approach considered in this article can be expanded to other nanocarrier/antioxidant systems.