The environmental situation in the world is one of the most important problems of our time. Huge mountains of unutilized plastic continue to pollute the atmosphere of our planet, its water and soil. In this regard, the creation of biodegradable materials is very relevant. Biodegradable polymers are designed to degrade upon disposal by the action of living organisms. They can be used in various fields: heavy and light industry, food industry, as well as medicine. The field of using depends on different properties that polymer material have. For instance, biodegradable material for medical use must posses a number of specific properties: do not cause a local inflammatory reaction, do not have a toxic and allergic effect on the body, do not have a carcinogenic effect, do not provoke the development of infection and maintain functional properties during the intended service life.
The time period during which the material decomposes under the influence of various factors directly depends on the composition of the polymer. The aim of our study was to correlate the data on the degradation time of composite polymer films with its composition.
In this work, different kinds of polymer films based on the natural polysaccharides blends were prepared for studying their degradation. Carboxymethyl cellulose (CMC) posess outstanding characteristics, including good biocompatibility, high thermal stability, and good affinity with body tissue, for which reason CMC-based material can be widely used [1]. Polyvinyl alcohol (PVA) is biocompatible, nontoxic, and relatively inert in body fluids. Such favourable properties have gained wide interest in its use for biomedical applications such as contact lenses, linings in artificial heart, and polymeric scaffolds for tissue engineering [2]. Sodium alginate (SA) can improve the residency stability of hydrophilic polymers in the body because of the embedding of hydrophilic polymers in the alginate network structure [3]. Alginate dressings in the dry form absorb wound fluid to re-gel, and the films then can supply water to a dry wound, maintaining a physiologically moist microenvironment and minimizing bacterial infection at the wound site during surgical operations. Alginate can be selectively ionically cross-linked with calcium ions to maximize its performance as a film. In addition, we used glycerol in different concentrations as the plasticizing agent in all samples.
To study the degradation process we choose medium of the PBS (phosphate buffered saline, pH = 7,4). It is a balanced salt solution used for a variety of cell culture applications, such as washing cells before dissociation, transporting cells or tissue, diluting cells for counting, and preparing reagents. It was prepared according to the method described in the source [3].
Prepared membranes were cut into 20×20 mm pieces, then placed in a test tube containing 30 ml of pH 7.4 phosphate-buffered saline for the study of degradation in vitro. The tubes were immersed in a 37 °C and observed for 16 weeks. At predetermined time intervals, the PBS was collected and replaced with a fresh one. The assessment was carried out according to the following marks: the beginning of destruction, complete decomposition of the film into pieces, complete dissolving.
During the experiment, the following results were obtained: the optimal concentration of the calcium chloride solution for crosslinking the alginate was selected in order to obtain a film with a established dissolution time For comparison, when the film is cross-linked with a 2% solution of calcium chloride, the destruction of the film begins on the second day, while without it, the film completely dissolves in 15 minutes. However, due to the interaction of phosphate anions and calcium cations, turbidity is formed due to the appearance of insoluble calcium phosphates and calcium hydrophosphates. An increase in the alginate content also extends the degradation time of the film compared to a single-component composition. The film with a mass content of 50% alginate disintegrated into segments in 3 days, while the 30% alginate film began to degrade on 2 days. The addition of PVA extends the degradation time, but all samples didn't dissolve during the all time of experiment. An important factor is the content of glycerol in the film sample: excess or lack of it negatively affects the process of degradation. For comparison, after treating the film with a 5% glycerol solution for 15, 30, and 90 seconds, destruction began on the 2nd, 7th, and 2nd day, respectively.
During the experiment, it can be concluded that the best compositions based on CMC and alginate completely dissolve within 3 weeks, therefore, they can be used for effective prevention of peritoneal adhesions. PVA-based films have shown themselves to be quite resistant to the external environment. They can be offered for use as the same packaging materials for products for which a long shelf life is important.