Use of biologically active sol–gel precursors to form chitosan aspartate shell nanoparticles

The paper examines chitosan aspartate shell nanoparticles formed in situ in the process of counterion condensation using novel bioactive sol–gel precursors: silicon methyltriglycerolate (MeSi(OGly)₃), silicon dimethyldiglycerolate (Me₂Si(OGly)₂), silicon tetraglycerolate (Si(OGly)₄), and silicon tetrapolyethylene glycolate (Si[O(C₂H₄O)₉H]), as well as titanium tetrapolyethylene glycolate (Ti[O(C₂H₄O)₉H]). The diameter of nanoparticles in the freshly prepared dispersion increases in the series of sol–gel precursors Me₂Si(OGly)₂→Si[O(C₂H₄O)₉H]→MeSi(OGly)₃→Si(OGly)₄→Ti[O(C₂H₄O)₉H], with the lowest polydispersity for Si(OGly)₄ and the highest for Ti[O(C₂H₄O)₉H]. Si- or Ti- coated nanoparticles (excluding Me₂Si(OGly)₂) correspond to kinetically stable nanodispersions: the electrokinetic potential was within 35‒40 mV and the conductivity was 0.58‒0.73 mS/cm. Modification with Me₂Si(OGly)₂ led to abnormally high values of the ζ-potential of the nanoparticles and the conductivity of the system. It was found that dispersions of chitosan aspartate nanoparticles with a sol–gel shell exhibited surface activity. During two-year storage, Si(OGly)₄ -stabilized dispersions maintained stable size and stable electrochemical and surface properties. A slight decrease in particle size and an increase in polydispersity were observed during storage of the samples functionalized with the sol–gel precursor Si[O(C₂H₄O)₉H]; a significant decrease in the size and ζ-potential of particles were observed for Ti[O(C₂H₄O)₉H], while a significant increase in size, polydispersity, and surface tension were noted for MeSi(OGly)₃ and Me₂Si(OGly)₂. Silicon tetraglycerolate was identified as the optimal modifier for stable chitosan aspartate nanoparticles, with the resulting polysiloxane-stabilized particles exhibiting dual bioactivity: plant growth stimulation across taxa and antifungal action against soil pathogens.

Acknowledgment

This research was funded by a grant from the Russian Science Foundation No. 24-16-00172, https://rscf.ru/project/24-16-00172/.