## 3 Results and Discussion  
It has previously been shown that grafting MMA on CC in an aqueous dispersion under visible light irradiation (\(\lambda\) = 400-700 nm) of the complex oxide RbTe\({}_{1.5}\)W\({}_{0.5}\)O\({}_{6}\) is associated with a series of transformations:  
* The irradiated complex oxide generates electron-hole pairs, which leads to different radical formations [37; 40]. There is a possibility of several chemical reactions occurring in the mixture. Collagen and MMA grafting are associated with an extremely active hydroxyl radical in the aqueous dispersion (Figure 1). * The hydroxyl radical forms oxygen- or carbon-centered radicals, which are more stable than the HO\(\bullet\) radical in the collagen macromolecule. It is related to separation of the hydrogen atom from the hydroxyl group in the amino acid residue (for example, hydroxproline) or the hydrocarbon part of the amino acid residue molecule (for example, alanine) [41]. These radicals interact with the monomer and form a grafted synthetic fragment. Simultaneously, there is MMA grafting on the surface of RbTe\({}_{1.5}\)W\({}_{0.5}\)O\({}_{6}\), and the formation of the MMA polymer is due to the reaction between hydroxyl radical and monomer [10]. Schematically, the reactions that occurred in a mixture of catalyst, MMA, and CC are shown in Figure 1.  
Evidence of PMMA grafting on collagen was the data of physicochemical analysis for the polymer isolated from the aqueous phase [10]. The curves of the molecular weight distribution (MWD) of the PMMA-CC graft copolymer were shifted to the region with high MW. Moreover, the MW values had increased in comparison to collagen. A comparison of the IR spectra for the PMMA-CC graft copolymer, collagen, and PMMA indicated that all of the characteristic bands of collagen and PMMA were observed for the graft copolymer. According to elemental analysis, the nitrogen content was decreased due to the grafting of a nitrogen-free synthetic fragment. The SEM results showed a new structural relief organization of the PMMA-CC graft copolymer in comparison to the initial collagen. This can be related to the compaction of the collagen fibers of the structural matrices. \begin{table}
\begin{tabular}{c l} \hline \hline
**Score** & **Score Characteristic** \\ \hline
0 & The germination of spores and conidia was not observed under a microscope \\ \hline
1 &
\begin{tabular}{l} Germinated spores and slightly developed mycelium were visible under \\ a microscope \\ \end{tabular} \\ \hline
2 &
\begin{tabular}{l} A developed mycelium was clearly visible under a microscope; sporulation \\ could be also observed \\ \end{tabular} \\ \hline
3 &
\begin{tabular}{l} Mycelium and/or sporulation were barely visible to the naked eye, but \\ clearly visible under a microscope \\ \end{tabular} \\ \hline
4 &
\begin{tabular}{l} The development of fungi was clearly visible to the naked eye, covering less \\ than 25\% of the test surface \\ \end{tabular} \\ \hline
5 &
\begin{tabular}{l} The development of fungi was clearly visible to the naked eye, covering \\ more than 25\% of the test surface \\ \end{tabular} \\ \hline \hline \end{tabular} Samples are considered fungi-resistant if the growth of fungi does not exceed a score of 2.  
\end{table} 
Table 2: Evaluation of the fungal resistance of samples. The effect of adding modifiers to the structure and properties of collagen with acrylate graft copolymers was controlled by the same physicochemical characteristics. It is important to note that collagen isolated from any natural substrate, even the most delicately as a high-molecular-weight polymer with MW \(\sim\)300 kDa, does not have sufficient mechanical strength. This is related to the destruction of intra- and intermolecular cross-links in a solution, which are formed during the biosynthesis of collagen in vivo and give its fibrils a stable structure, mechanical strength, and resistance to enzymes.