Silver-doped self-assembling di-phenylalanine hydrogels as wound dressing biomaterials

Abstract

Chronic and acute wounds can be quickly contaminated and infected by microorganisms such as bacteria, multi-resistant organisms or fungi. The introduction of silver as anti-microbial agent into wound management has widely been demonstrated to be effective and contribute to wound healing. As a consequence, many approaches and different materials have been employed to synthesize antibacterial silver-hydrogels. In this work the introduction of silver particles into the fibrillar structure of self-assembling aromatic di-phenylalanine derivatives modified with aromatic groups such as 9-fluorenylmethoxycarbonyl is proposed to produce antibacterial wound dressings. Hydrogels doped with increasing amounts of silver were tested and adopted to modify flax textiles. The influence of silver on the structure of hydrogels was studied using light and confocal microscopy, while SEM-EDX allowed the characterization of the hydrogel coating on the surface of the textile substrates as well as the identification and distribution of silver nanoparticles. The antibacterial potential of the treated flax was demonstrated through microbiological tests on Staphylococcus aureus. The combination of the physico-chemical and anti-bacterial properties, together with the ease of preparation of these biomaterials, fulfils the requirement of clinically-effective wound dressings.

Stimuli-responsive Hydrogels for Textile Functionalisation: A Review

“…e latter include combinations of NiPAAm with chitosan [59,[72][73][74][75][76][77][78][79], ALA [80], MAA [81] or N-aminoethyl methacrylate (AEMA) [82]. Hydrogels have been synthesised using various techniques such as surfactant-free dispersion copolymerisation with a conventional stirring technique [59,[72][73][74][75][76][77], mixing with the help of an ultrasound bath [78][79]83], copolymer synthesis [82], coupling of a triblock copolymer [61], surface-initiated atom transfer radical polymerisation (ATRP) [26], free radical polymerisation [81] and precipitation polymerisation [76]. In most cases, surfactant-free dispersion polymerisation is used to synthesise both microgels and nanogels.…”

“…In this way, particles with a diameter of 81.2 nm were obtained [90]. Other microgels used for textile modi cation have been based on carboxymethylcellulose (CMC) in combination with fumaric acid as a crosslinker [91], di-phenylalanine [83], CMC and hydroxyethyl cellulose [92] and poly (ethylene glycol) (PEG) and poly(ε-caprolactone) (PCL) [61]. In the case of the synthesis of nanogels, PVA- [93], β-cyclodextrin (β-CD)- [94], hydrophobised-pullulan- [95] and collagen-bearing pullulan- [96] based polymers have been used.…”

“…Photo-induced gra copolymerisation of poly-NiPAAm on previously plasma-treated textile substrates has also been carried out through copolymerisation with polypropylene (PP) [99], with the addition of chitosan [100] and with a polyethylene terephthalate (PET) lm [99]. Microgels based on carboxymethyl chitosan (CMCh) and PVA [112], CMC and fumaric acid [91], CMC and hydroxyethyl cellulose derivatives [92], self-assembling di-phenylalanine [83], glycol and ε-caprolactone [62], collagen [30], and polyacrylic acid and β-cyclodextrin [107] have been used. Poly-NIPAAm-based microgels have been by far the most studied because of the LCST of the polymer, which is in the body temperature range.…”

Nonconventional Routes to Silver Nanoantimicrobials

“…Natural and synthetic fibers deposited with silver nanoparticles demonstrated long-lasting antifungal and antibacterial capabilities on many micro-organisms, no skin irritation effect in vivo, excellent adhesion of the coating to the fibers, and durability in laundry (Paladini et al, 2014c). Silver-coated cotton and flax substrates have been developed as effective wound dressing biomaterials for the prevention of wound infections (Paladini et al, 2013a(Paladini et al, , 2014b; silver-treated textiles have also been proposed for other biomedical applications such as the production of antimicrobial bed linens for the prevention of cross-transmission among patients (Paladini et al, 2014c). The transmission of infectious diseases can also be associated with public places such as waiting rooms, schools, or public transportation, where hand-touch surfaces can easily get colonized by bacteria and fungi.…”

Mechanically Responsive Antibacterial Plasma Polymer Coatings for Textile Biomaterials

“…Therefore, the use of alternative antibacterial agents is now highly desired in the medical field. In this framework, silver species that have long been known to have antimicrobial activity are used in more and more biomedical sectors . No toxicity to human cells has been highlighted for silver ions (Ag + ) up to micromolar concentrations .…”