**4. Conclusion**

The modern Fourier transform infrared spectroscopic techniques (linear scan, reflection, trans‐ mission, mapping, video analysis) in combination with diffraction (XRD), energy‐dispersive X‐ray (EDX), spectrophotometric (UV‐Vis), and electronic microscopy (SEM) methods are applied in the structure analysis of synthesized green nanoparticles and polysaccharide complexes, as well as for the confirmation of suggested types of complexes structure and for the testing of samples homogeneity. In this respect, silver nanoparticles were prepared with dextran sulfate or carboxymethyl dextran as a reducing and capping agent, while cobalt biocomplexes were synthesized with reduced low‐molar dextran as ligand. Comparison of FTIR spectra of initial exopolysaccharide compounds (DS, CMD, RLMD) and final products (AgNP‐DS, AgNP‐CMD, Co(II)‐RLMD complexes), in the specific region of characteristic functional group vibrations, has indicated on coordination complexes forming as a part of complex structure. FTIR spectroscopic analysis has shown that interactions between metal ions and specific polysaccharide functional groups have steric character and suggest 4 C1 con‐ formation of the glucopyranose unit. The existence of nanoparticles (in range of 10–60 nm) has been confirmed by SPR band in the UV‐Vis spectra, by SEM microscopy, and XRD meth‐

ods. AgNP size was determined on the Bragg reflection at 38.24°2θ, yielding mean crystal‐ lite size of 40 ± 4 nm. It has been found that crystalline structures of silver complexes are face‐centered cubic type by XRD method. Morphological SEM analysis has been shown that formed nanoparticles are spherical and inclined to aggregation. It has been established that size distribution and morphology of mentioned nanoparticles (by SEM and FTIR microspec‐ troscopy methods), as well as the structural form of the complexes (by FTIR, UV‐Vis, XRD), are depended on ligand properties (such as constitution, degree of amorphousness or crystal‐ linity, molar mass, units conformation, chain linearity) and on the reaction conditions (such as metal‐ligand weight ratio, reaction time, temperature, and pH values). Also, antimicrobial and antifungal activities of synthesized AgNP have been determined. The highest inhibition zones were observed against *P. aeruginosa* and *B. luteusin haus strain*, while *P. vulgaris* was the least sensitive to the nanoparticles. The fungus *Penicillium* spp. was more sensitive to the AgNP comparing to the other two fungal strains. Having in mind these results, it can be con‐ cluded that this design of silver nanoparticles synthesis has a great potential because of their antimicrobial activity.
