Antimicrobial Activity of Starch Hydrogel Incorporated with Copper Nanoparticles

Abstract

In order to obtain an antimicrobial gel, a starch-based hydrogel reinforced with silica-coated copper nanoparticles (Cu NPs) was developed. Cu NPs were synthesized by use of a copper salt and hydrazine as a reducing agent. In order to enhance Cu NP stability over time, they were synthesized in a starch medium followed by a silica coating. The starch hydrogel was prepared by use of urea and water as plasticizers and it was treated with different concentrations of silica-coated copper nanoparticles (Si-Cu NPs). The obtained materials were characterized by Fourier transform infrared (FT-IR) spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, scanning electron microscopy (SEM), and rheometry. FT-IR and EPR spectra were used for characterization of Cu NPs and Si-Cu NPs, confirming that a starch cap was formed around the Cu NP and demonstrating the stability of the copper nanoparticle after the silica coating step. SEM images showed Cu NP, Si-Cu NP, and hydrogel morphology. The particle size was polydisperse and the structure of the gels changed along with particle concentration. Increased NP content led to larger pores in starch structure. These results were in accordance with the rheological behavior, where reinforcement by the Si-Cu NP was seen. Antimicrobial activity was evaluated against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacterial species. The hydrogels were demonstrated to maintain antimicrobial activity for at least four cycles of use. A dermal acute toxicity test showed that the material could be scored as slightly irritant, proving its biocompatibility. With these advantages, it is believed that the designed Si-Cu NP loaded hydrogel may show high potential for applications in various clinical fields, such as wound dressings and fillers.

Comparative environmental fate and toxicity of copper nanomaterials

“…Many applications involve the traditional role of Cu as a conductor, such as conductive dyes (Albrecht et al, 2016;Hokita et al, 2015;Tam and Ng, 2015;Kharisov and Kharissova, 2010;Tsai et al, 2015;Gopalan et al, 2016) or heat transfer fluids (Park et al, 2015;Montes et al, 2015;Azizi et al, 2016;Rizwan-ul-Haq et al, 2016), but the use of nano-Cu is rapidly expanding into novel applications such as catalysts in organic synthesis (Dugal and Mascarenhas, 2015;Lennox et al, 2016;Barot et al, 2016), sensors (Albrecht et al, 2016;Tsai et al, 2015;Gopalan et al, 2016;Brahman et al, 2016;Pourbeyram and Mehdizadeh, 2016), solar cells (Yoon et al, 2010;Parveen et al, 2016;Shen et al, 2016), light-emitting diodes , hydrogen generation (Liu et al, 2015a;Liu et al, 2015b), and drug delivery (Woźniak-Budych et al, 2016). Based on the antifungal and antimicrobial properties of Cu + 2 , Cu NPs are actively being developed for applications in agriculture and food preservation (Park et al, 2015;Montes et al, 2015;Dugal and Mascarenhas, 2015;Ray et al, 2015;Kalatehjari et al, 2015;Ponmurugan et al, 2016;Maniprasad et al, 2015;Majumder and Neogi, 2016;Villanueva et al, 2016), textiles (Majumder and Neogi, 2016;Sedighi and Montazer, 2016), ...…”

Starch–metal complexes and metal compounds

“…Potato starch gels provided a suitable matrix hindering nanosilver, nanogold particles and bimetallic nanoAg/Au particles from agglomeration. Villanueva et al . prepared nanocopper particles in cornstarch.…”

Low‐temperature assembling of naturally driven copper ferrite starch nanocomposites hydrogel with magnetic and antibacterial activities

“…Natural polymers are suitable for making hydrogels because of biocompatibility and biodegradability . Starch is a polysaccharide with low cost, abundant and hydrogel ability . Starch hydrogels were often prepared by graft copolymerization of synthetic polymers such as acrylamide and acrylonitrile.…”

“…The nanoparticles can be simply mixed with the hydrogel raw material or synthesized during the processing entrapped within the swelled hydrogel in an aqueous media or synthesized between the free‐space of networks in the swollen gel . Mixing metal nanoparticles with hydrogels leads to the special properties for various biomedical applications …”