(174b) Design of a Drug Delivery System Based on Levan-Capped Silver Nanoparticles for Bactericidal Purposes

Silver has been identified as a good agent for controlling the growth of microorganisms, mainly bacteria. However, its current application in the pharmaceutical industry has some drawbacks, such as biodistribution, release and the required dose. In order to overcome these problems, the development of a drug delivery system formed by a hydrogel containing levan-capped silver nanoparticles has been developed in this work.

Levan is a polymer based on fructoses that has an important advantage compared with other polysaccharides because it can act as reducing and capping agent for gold and silver, creating nanoparticles (1). This possibility has been explored previously for catalysis purposes but not for controlling bacteria population.

Levan-capped silver nanoparticles were characterized by Dynamic Light Scattering (DLS), to study particle size distribution (36.9 ± 11.8 nm) and zeta potential (-22.3 ± 5.8 mV). Transmission Electron Microscopy (TEM) showed spherical and monodisperse nanoparticles, whereas infrared, spectrophometric and spectrosmetric analysis checked the presence of silver in the nanoparticles. These nanoparticles were tested in microwell plates against two different bacteria strains (Bacillus subtilis as Gram positive, and Escherichia coli as Gram negative) and the results followed a single-hit multiple-target, with a lethal dose of 12.6 ppm for B. subtilis and 6.8 ppm for E. coli. At the same time, the number of targets (n) were 1.904 for B. subtilis and 1.868 for E. coli).

The nanoparticles were also included in an alginate gel for improving silver release. This release was studied and modelling (by gPROMS) when it is exposed to a bacterial solution, analyzing the control of microorganism’s growth. The main parameters of release were estimated, so that these simulations can be used in further studies in order to optimize the release of silver nanoparticles from a gel for topical administration.

Acknowledgments:

Authors want to acknowledge the financial support for research from Spanish Ministry of Science (project grant: CTQ2016-78988-R). Álvaro González-Garcinuño also acknowledges Spanish Ministry of Education for his PhD. Fellowship (FPU14/04914).

References:

(1): K.B.A. Ahmed, D. Kalla, K.B. Uppuluri, V. Anbazhagan, Green synthesis of silver and gold nanoparticles employing levan, a biopolymer from Acetobacter xylinum NCIM 2526, as a reducing agent and capping agent, Carbohyd. Polym. 112 (2014) 539-545