Title

Novel Copper (Cu) Loaded Core-Shell Silica Nanoparticles With Improved Cu Bioavailability: Synthesis, Characterization And Study Of Antibacterial Properties

Keywords

Antibacterial; Copper biocide; Copper loaded silica; Core-shell nanoparticle; Sol-gel

Abstract

We report synthesis of a novel core-shell silica based antimicrobial nanoparticles where the silica shell has been engineered to accommodate copper (Cu). Synthesis of the core-shell Cu-silica nanoparticle (C-S CuSiO 2NP) involves preparation of base-hydrolyzed Stöber silica "seed" particles first, followed by the acid-catalyzed seeded growth of the Cu-silica shell layer around the core. The Scanning Electron Microscopy (SEM) and the Transmission Electron Microscopy (TEM) measured the seed particle size to be ∼380 nm and the shell thickness to be ∼35 nm. The SEM particle characterization confirms formation of highly monodispersed particles with smooth surface morphology. Characterization of particle size distribution in solution by Dynamic Light Scattering (DLS) technique was fairly consistent with the electron microscopy results. Loading of Cu to nanoparticles was confirmed by the SEM-Energy Dispersive X-Ray Spectroscopy (EDS) and Atomic Absorption Spectroscopy (AAS). The Cu loading was estimated to be 0.098 μg of metallic copper per mg of C-S CuSiO 2NP material by the AAS technique. Antibacterial efficacy of C-S CuSiO 2NP was evaluated against E.coli and B.subtilis using Cu hydroxide ("Insoluble" Cu compound, sub-micron size particles) as positive control and silica "seed" particles (without Cu loading) as negative control. Bacterial growth in solution was measured against different concentrations of C-S CuSiO 2NP to determine the Minimum Inhibitory Concentration (MIC) value. The estimated MIC values were 2.4 μg metallic Cu/mL for both E.coli and B.subtilis. Bac-light fluorescence microscopy based assay was used to count relative population of the live and dead bacteria cells. Antibacterial study clearly shows that C-S CuSiO 2NP is more effective than insoluble Cu hydroxide particles at equivalent metallic Cu concentration, suggesting improvement of Cu bioavailability (i.e., more soluble Cu) in C-SCuSiO 2NP material due to its core-shell design. Copyright © 2012 American Scientific Publishers All rights reserved.

Publication Date

8-1-2012

Publication Title

Journal of Biomedical Nanotechnology

Volume

8

Issue

4

Number of Pages

558-566

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1166/jbn.2012.1423

Socpus ID

84865137270 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84865137270

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