Medical hydrogels based on bioactive compounds. Synthesis, properties, and possible application for preparing bactericidal materials

Abstract

Several physicochemical analytical methods were used to study aqueous solutions and hydrogels based on L-cysteine and silver nitrate. It was found that anions played a decisive role in forming the threedimensional gel-network in dilute silver-cysteine solutions. The ability to use silver-cysteine solutions and hydrogels to prepare bactericidal fi bers and fabrics was examined.Self-assembly of supramolecular structures in solutions has recently attracted increased worldwide interest. This timely problem comprises studies of the formation of very important physicochemical and biological entities such as micelles, liposomes, lipoproteides, membranes, clusters, immune complexes, physical gels, etc.[1]. A common feature of the aforementioned entities is the absence of strong chemical bonds between the interacting components. The driving forces for forming the respective structures are electrostatic and van-der-Waals interactions, hydrophobic effects, H-bonds, and weak donor-acceptor bonds. Dilute gels occupy a special place among these entities. Only a few such molecular systems are known. In particular, they include the polysaccharide agar-agar, mixtures of muscle proteins, and calcium germinate [2].Gel formation in an aqueous solution with a low concentration of domestically produced L-cysteine and silver nitrate was fi rst established several years ago [3,4].The heightened interest in this system is completely understandable. First, the hydrogel is a unique model system for studying self-assembly processes in dilute aqueous solution (concentration 0.1% and lower). Second, the system can be used in medical practice as an independent medical preparation or as a matrix for formulating other preparations because of the presence of silver in it.The fact that silver in its various forms (ions, salts, colloidal solutions, nanoparticles) has been used for a long time in medical practice argues in favor of the second factor. The antibacterial properties of this element are well known. Interest in the use of silver to treat infectious diseases decreased with the emergence of antibiotics. However, many antibiotics have recently become obsolete because of the appearance of resistance to them in constantly evolving new strains of bacteria. This opens broad possibilities for the use of silver as an alternative to antibiotics that have become ineffective [5].A problematic issue for the use of silver nanoparticles and ions is the choice of the matrix for their practical application. Solutions of silver nanoparticles and ions, most often aqueous but other solvents are also employed, are used most commonly. Silver in such a form is used to prepare infusions, preservatives for various media, and disinfectants for medical instruments.Furthermore, materials consisting of either a solid compound (inorganic matrices, in particular silica gel) or condensed substances (gels, polymers) are often used as the matrix [6][7][8]. The practical application of silver is broadest for matrices of block polymers and gels such as suturing materials, w...

Supramolecular Hydrogelators and Hydrogels: From Soft Matter to Molecular Biomaterials

“…Several comprehensive reviews have focused on this subject. 1066 , 1067 In the following section, we only give a brief discussion of the works on antibacterial hydrogelators reported over the past decade.…”

Antibacterial Hydrogels

“…Polylysine, a popular AMP reported by Zhou et al, has been applied in photopolymerized antibacterial hydrogels, which generated promising coatings for medical devices and implants . In addition to antibacterial peptide maximin‐4‐loaded PHEMA hydrogels, l ‐cysteine‐ and silver nitrate (AgNO 3 )‐loaded hydrogels were proved to possess antibacterial activity against Staphylococci , Bacilli , Escherichia , and P. aeruginosa strains …”

Antimicrobial hydrogels: promising materials for medical application

“…AMP maximin-4-loaded poly (2-hydroxyethyl methacrylate) hydrogels, 244 l-cysteine-and silver nitrate-loaded hydrogels were proved to have qualified antibacterial activity. 245 Although AMPs still have disadvantages, such as tissue toxicity and hemolysis, 246,247 they also exhibited a higher antimicrobial biocompatibility index value compared with synthetic drugs with similar structures, 248,249 and a lot of studies have attempted to improve the biocompatibility. [234][235][236] A cell adhesive polypeptide and PEG hydrogel with inherent antibacterial activity was developed by Song et al as a potential scaffold for cutaneous wound healing.…”

“…286 Some researchers synthesized antimicrobial Ag NPs and impregnated them into antifouling zwitterionic hydrogels, thus getting mussel-inspired, antifouling, antibacterial hydrogels with great potential in wound healing applications (Figure 8). 287 Both bactericidal hydrogels based on l-cysteine and silver nitrate and Ag(I)-glutathione hydrogel which exhibited improved cytocompatibility were reported in 2011, 245,288 offering more possibilities on potential application in biomedical field such as burn wound dressings. For other combinations, Ag NP-curcumin composite hydrogels demonstrated that incorporation of curcumin into these hydrogel nanocomposites would further enhance their antibacterial efficacy.…”