BIODEGRADABLE FILM MATERIALS BASED ON POLYMER HYDROGELS AND SILVER NANOPARTICLES
This work deals with various aspects of obtaining and evaluating the effectiveness of biodegradable film materials based on polymer hydrogels and silver nanoparticles. Polyvinyl alcohol and potato and maize starch are used as a matrix in the materials under consideration. These polymers are safe for humans and allow of obtaining biodegradable materials. Introduction of silver nanoparticles into the film materials under consideration makes it possible to increase their antibacterial and fungicidal properties. The comparative analysis of the obtained film materials demonstrated the most promising materials based on polyvinyl alcohol and maize starch with silver nanoparticles (PVS/MaizeStarch/Agnano).
BIODEGRADABLE FILM MATERIALS BASED ON POLYMER HYDROGELS AND SILVER NANOPARTICLES
O.A.Farus1, Cand. of Sci. (Chemical), Docent, ORCID: 0000-0002-1426-6534 / email@example.com
Abstract. This work deals with various aspects of obtaining and evaluating the effectiveness of biodegradable film materials based on polymer hydrogels and silver nanoparticles. Polyvinyl alcohol and potato and maize starch are used as a matrix in the materials under consideration. These polymers are safe for humans and allow of obtaining biodegradable materials. Introduction of silver nanoparticles into the film materials under consideration makes it possible to increase their antibacterial and fungicidal properties. The comparative analysis of the obtained film materials demonstrated the most promising materials based on polyvinyl alcohol and maize starch with silver nanoparticles (PVS/MaizeStarch/Agnano).
Keywords: biodegradable film materials, hydrogel, silver nanoparticles, antibacterial and fungicidal properties
For citation: O.A. Farus. Biodegradable film materials based on hydrogels polymers and silver nanoparticles. NANOINDUSTRY. 2022. V. 15, no. 3–4. PP. 196–203. https://doi.org/10.22184/1993-8578.2022.15.3-4.196.203
Modern reality dictates new living conditions. Hence, pollution of the environment with household hard-to-degrade waste, most commonly household plastics and polyethylene is one of the global problems of the world. The coronavirus pandemic has contributed to emergence of a new term – COVID-19 rubbish. COVID-19 rubbish refers to the waste generated by use of personal protective equipment, such as used disposable masks, gloves and disinfectant vials .
According to the Environmental Science & Technology Journal, 129 billion masks and 65 billion gloves are discarded every month. This means that nowadays there is a significant increase of burden on the environment in the form of virtually indestructible plastic and polyethylene. In order to reduce environmental pollution, it is necessary to move towards the widespread use of biodegradable materials. At the same time, biodegradable materials with additional functional properties have the greatest practical relevance . Therefore, the practice of involving nanochemistry in the development of biodegradable materials is one of the ways to reduce the technogenic burden on the environment.
In most cases, modern nanomaterials are not used or produced as monocomponent systems consisting of several types of isolated or compacted nanoparticles, but rather in the form of nanocomposites (composite nanomaterials) containing at least 2 components where at least one has a size range of 1–100 nm. From the point of view of the described problem, biodegradable materials modified with nanoparticles have good prospects. These materials are promising for several reasons. Firstly, the biodegradability of the composite material can be achieved through the right choice of its base, and secondly, use of the functional properties of materials can be changed by introduction of different types of nanoparticles.
As part of this study, the methods for the synthesis of biodegradable films have been developed. Analysis of literature data shows that such natural polymer as starch is quite effectively used in producing biodegradable materials [3, 4]. Wide application of starch is due to its composition. It consists of two polymeric components, amylose (linear molecules) and amylopectin (branched molecules), whose chains are constructed of α-D-glucopyranose residues.
The gel-forming component in starch is amylose. Analysis of literature data showed that the percentage of amylose in potato and maize starches is 20% (more often 13–17%) and 25% respectively. Consequently, maize starch, which forms more stable gels and films, is preferable for use.
In addition to starch, polyvinyl alcohol, a water-soluble polymer, is widely used in medicine and the food industry as an emulsifier and can also be used as the base . The polymers under consideration as the basis for biodegradable materials have a number of advantages. On the one hand, they have universal binding properties, are capable of film formation, are water-soluble and safe for the human body, which makes it possible to widely use nanocomposite materials based on them, and on the other hand, these polymers can act as stabilizers of metal nanoparticles.
In this work silver nanoparticles were used as a modifier. They were obtained by direct synthesis from silver nitrate solution in the presence of a reducing agent (N2H4 hydrazine) and a functional polymer:
Ag+ + N2H4 + 4OH- = Ag0 + N2 + 4H2O.
Stabilisation of silver nanoparticles is achieved by encapsulating a nanoparticle in a hydrophobic polymer core.
Preliminary tests show that the materials obtained from pure starch hydrogel are brittle, inflexible and easily crumbling. Therefore, in order to improve quality of the obtained materials it was decided to use hydrogels based on polyvinyl alcohol and starch as the matrix.
The quantitative composition used for synthesis of a particular biomaterial is shown in Table 1.
Techniques for production of polymer films modified with nanoparticles are also in progress of development. These techniques have been tested and repeatedly validated in practice.
Depending on the base the biomaterials were synthesised from, they have been given names that correlated with their composition (Table 2).
RESULTS AND DISCUSSION
Since the obtained materials should theoretically be biodegradable, we studied the biodegradability of the polymers obtained. The biodegradability of the obtained materials was assessed using the burial test. When using this test, the rate of the material biodegradation is assessed by changes in their appearance after exposure to soil in given time intervals (2, 4, 6 and 12 months). In addition to the visual assessment of the samples, a check weighing was carried out using electronic analytical scales Vibra ensuring the accuracy of ±0.0001. The data obtained are shown in Table 3.
Hence, we can arrange the obtained biomaterials in order of their decomposition rate:
PVA/MaizeStarch/Agnano and PVA/MaizeStarch
The analysis of the obtained data suggests that the materials containing starch have the shortest decomposition time - the higher the starch content, the shorter the decomposition time. This may explain attractiveness of starch as a food for soil-dwelling destructors. It should be noted that the materials containing silver nanoparticles have longer decomposition times than their counterparts without nanoparticles. This fact can be explained by the antibacterial and fungicidal activity of the considered nanoparticles [6, 7].
As silver nanoparticles have antibacterial properties, the study evaluated the antibacterial properties of the nanomaterials obtained on the bacteria belonging to the intestinal group (Escherichia coli). Petri dishes dia. 9.3, E. coli-rich water, Endo nutrient medium and 2.0 × 2.0 cm samples of degradable biomaterial were used for the study. Before biotesting, the dishes were thoroughly washed with a chromium mixture, followed by a baking soda solution and distilled water.
During the study, we prepared nutrient media and poured it into five Petri dishes. Intestinal bacteria isolated from drinking water were superficially inoculated into all five dishes. Petri dish number one was used as a standard, no material was placed in it, and the material to be analysed was placed in the centre of the other four Petri dishes:
- № 2 – PVA/MaizeStarch
- № 3 – PVA
- № 4 – PVA/MaizeStarch/Agnano
- № 5 – PVA/PotStarch/MaizeStarch
Bacterial growth continued for 24 hours at room temperature. The study shows that a lysis zone was only observed in the Petri dish with the silver nanoparticle sample (PVA/MaizeStarch/Agnano). In all other samples uniform growth of E. coli was observed. We conclude that the developed nanomaterial has antibacterial activity.
It is interesting to study the effect of the developed materials on preservation of foodstuffs. Wheat bread was chosen as the object of research. For this purpose, pieces of white bread of equal weight were placed in Petri dishes and favourable conditions were created for the development of Mucor (Mucor) fungus. Materials with an identical polymer matrix composition were selected for comparison, but one sample contained silver nanoparticles and the other did not (PVA/MaizeStarch and PVA/MaizeStarch/Agnano). Experimental materials were placed on the bread samples. The experiment lasted for seven days. The obtained results are shown in Table 4.
Analysis of the obtained results shows that in all Petri dishes, except for Petri dish No. 4, there was a complete overgrowth of the Mucor mould fungus, and in Petri dishes with PVA/MaizeStarch/Agnano material, the fungus overgrowth occurred only in the lower part where there was no composite material.
Thus, the analysis of the current environmental situation calls for active use of renewable resources and materials that cause the least damage to the environment, which include biodegradable composites. The study revealed that the effectiveness of these composites can be significantly improved by modifying them. Silver nanoparticles are among the most effective modifying agents. The effectiveness of their use is due to improvement of antibacterial and fungicidal properties of biodegradable materials and it is necessary to consider the effect of the concentration of these particles in the material upon the increase of the decomposition time of the obtained materials.
PEER REVIEW INFO
Editorial board thanks the anonymous reviewer(s) for their contribution to the peer review of this work. It is also grateful for their consent to publish papers on the journal’s website and SEL eLibrary eLIBRARY.RU. ■
Declaration of Competing Interest. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.