## 3 Description of the State of Knowledge
### Green Biosynthesis of Silver Nanoparticles with Antifungal Properties  
Of great interest is the green synthesis of nanoparticles, a technique based on the use of plants and their components as reducing agents (Figure 4). The possibility of their use results from the fact that many plants are rich in antioxidant compounds, such as polyphenols, flavonoids, and amide compounds. They have reducing hydroxyl groups that have the ability to reduce silver ions to elemental silver [46]. These methods are usually simple, convenient, cost-effective, and, most importantly, environmentally friendly, as they eliminate the need for toxic chemicals and solvents. Various species of microorganisms can also be used for the synthesis of nanoparticles; however, a necessary condition in this method is to maintain the asepticity of the entire process [47; 48]. Figure 4: Green synthesis scheme based on the example of the synthesis of silver nanoparticles using plant extracts. The first step includes the selection and appropriate preparation of the plant, followed by the extraction process and obtaining the plant extract, which, in the next stage, is mixed with a solution of silver salts under the appropriate set of conditions. Then, the phytochemicalomotes from the plant extract act as reducing agents and cause the conversion of Ag\({}^{+}\) ions to Ag\({}^{0}\) nanoparticles. AgNPs synthesized by _Artemisia amnua_, plants from the Asteraceae family, were evaluated against three species of _Candida: C. albicans, C. tropicalis_, and C. _glabrata_. The particles showed activity against all the species used in the study with an MIC value in the range of 80-120 \(\upmu\)g/mL [49]. Silver nanoparticles synthesized using been back extracts (BBE), silver acetate, and nitrate salts (AgNPs Acetate BBE and AgNPs Nitrate BBE) were tested as well. The antifungal activity of the compounds was tested against _Candida_ reference strains (_C. albicans, C. parapsilosis, C. Krusei, C. auris_, and _C. guilliermondii_). Growth inhibition was observed in all the tested strains in the presence of both AgNP BBEs, with the exception of C. _auris_. The tested compounds also inhibited biofilm formation but only against _C. albicans_ and _C. guilliermondii_. In addition, synergistic activity of the nanoparticles was observed in combination with funconazole against _C. parapsilosis_ and _C. guilliermondii_[43]. Spruce bark extracts (SBE) were also used for AgNP biosynthesis. Acetate and nitrate silver salts (AgNPs SBE acetate, AgNPs SBE nitrate) against the same five _Candida_ strains were tested as above. AgNP SBEs inhibited the growth of _C. parapsilosis, C. Krusei, and C. guilliermondii_; moreover, they showed a synergistic effect with funconazole against _C. parapsilosis_ and _C. guilliermondii_ and inhibited biofilm formation by _C. albicans, C. auris_, and _C. guilliermondii_[50]. Other research focused on AgNPs produced by the callus extract from _Solanum incanum_ L., a plant from the nightshade family. Plant pathogenic fungi _F. oxysporum, Alternaria alternata, Aspergillus niger_, and _Pythium ultimum_ were used. At a concentration of 25 \(\upmu\)g/mL, AgNPsNPs inhibited the growth of these fungi in the range of approximately 30-50% depending on the strain, while these values at a concentration of 200 \(\upmu\)g/mL ranged between 65 and 90% [51]. [PERSON] et al. carried out an environmentally friendly synthesis of silver nanoparticles using _Pseudomonas indica_ [PERSON] [52]. The studies of the antifungal activity of these molecules focused on fungi that cause mucormyosis, a dangerous disease that affects mainly people with diabetes or cancer or after transplants. The Rhizopus microsporus, Mucor racemous, and Syncephalastrum racemous species were used in the study. The results showed antifungal activity of nanoparticles against all the tested fungi at a concentration of 400 \(\upmu\)g/mL, with the MIC values of 50, 50, and 100 \(\upmu\)g/mL against _R. microsporus, S. racemosum, and M. racemosus_, respectively.