Superabsorbent wound dressing with silver nanoparticles formed in situ by gamma radiation: low-cost production

Abstract

Healing devices must be designed to provide the basic needs for the different types of wounds. One of the most complex problems is the development of wound dressing based in non-toxic superabsorbent polymers, which can satisfy highly exudate wounds. At present time, there are few materials used in the biomedical area with a high level of water absorption in highly exudative wounds. The common material can cause toxicity (acrylates) or they are expensive (alginates). The high cost of treatment with superabsorbent devices make the final price expensive for Brazil public health system (SUS). This problem can be resolved using modified non-toxic abundant polymers to obtain superabsorbent polymers (SAP) at low cost. Recently, PVA was modified with glyoxylic acid trough formation of cyclic acetals to obtain poly(vinylglyoxylic acid) (PVGA), but the chemical crosslinking reaction to obtain the SAP, decreases gradually the polymer absorption of exudates. However, crosslinking reaction is necessary to synthesize a stable superabsorbent hydrogel. In order to crosslink PVGA without decrease of superabsorbent or mechanical properties, another synthesis route has to be studied. The decrease in absorption capacity can be tracked with other strategy: ionizing radiation. Radiation induced crosslinking do not use the crossover points of the acid functional groups instead, the CH2 groups in PVGA chains. Then free radicals and macroradiacals can recombine to make crosslinking chains without decrease of superabsorption because the free acids group's are not involved.SAP polymers tend to decrease their mechanical properties when swollen in water. Therefore wound dressings based on SAP's can be easily destroyed by the body movement, mainly from arms and legs. The mechanical stability can be improved with addition of polysaccharides like carboxymethyl cellulose (CMS), which is inexpensive, biodegradable, hydrophilic and a non-cytotoxic polymer. In the treatment of open highly exudate wounds, a bactericide agent is essential when wounds are infected. Silver nanoparticles (AgNP) have been extensively used due to effectivity against a large spectrum of bacteria, but nanoparticles are expensive. It is possible to synthetize in situ AgNP from silver ions through free electrons generated by irradiation of system PVGA/CMS/Ag+ in water. The irradiated system PVGA/CMS/AgNP has a large quantity of radical species, which can generate different final polymer architectures with different physicochemical properties: semi-penetrating or interpenetrating networks, grafting copolymers or comb-type copolymers. Polymer architectures will be studied in order to improve key properties (mechanical, swelling kinetics and superabsorption). The project aims is develop a super absorbent wound dressing, with good mechanical properties, bactericide, sterilized and with low cost of production based on simultaneous sterilization, crosslinking and nanosilver formation. The superabsorbent hydrogel can cover growing demands of medical devices for the treatment of highly exudate wounds in Brazil. (AU)