Copper‐Based Nanostructured Coatings on Natural Cellulose: Nanocomposites Exhibiting Rapid and Efficient Inhibition of a Multi‐Drug Resistant Wound Pathogen, A. baumannii, and Mammalian Cell Biocompatibility In Vitro

Abstract

This paper describes a layer‐by‐layer (LBL) electrostatic self‐assembly process for fabricating highly efficient antimicrobial nanocoatings on a natural cellulose substrate. The composite materials comprise a chemically modified cotton substrate and a layer of sub‐5 nm copper‐based nanoparticles. The LBL process involves a chemical preconditioning step to impart high negative surface charge on the cotton substrate for chelation controlled binding of cupric ions (Cu2+), followed by chemical reduction to yield nanostructured coatings on cotton fibers. These model wound dressings exhibit rapid and efficient killing of a multidrug resistant bacterial wound pathogen, A. baumannii, where an 8‐log reduction in bacterial growth can be achieved in as little as 10 min of contact. Comparative silver‐based nanocoated wound dressings–a more conventional antimicrobial composite material–exhibit much lower antimicrobial efficiencies; a 5‐log reduction in A. baumannii growth is possible after 24 h exposure times to silver nanoparticle‐coated cotton substrates. The copper nanoparticle–cotton composites described herein also resist leaching of copper species in the presence of buffer, and exhibit an order of magnitude higher killing efficiency using 20 times less total metal when compared to tests using soluble Cu2+. Together these data suggest that copper‐based nanoparticle‐coated cotton materials have facile antimicrobial properties in the presence of A. baumannii through a process that may be associated with contact killing, and not simply due to enhanced release of metal ion. The biocompatibility of these copper‐cotton composites toward embryonic fibroblast stem cells in vitro suggests their potential as a new paradigm in metal‐based wound care and combating pathogenic bacterial infections.

Drying cellulose-based materials containing copper nanoparticles

“…). Similar phenomenon was reported by Cady et al (2011). After the sprayand freeze-drying process, the CMC-copper nanoparticles exhibited a yellow and green color, respectively.…”

“…cannot be distinguished from one another based on XPS analysis only since both peaks appear in the range between 932 and 933 eV and the Cu2p 3/2 bands for the two species are separated by 0.1 eV (Cady et al 2011). The absence of Cu2p 3/2 peaks between 933 and 934 eV suggests that no Cu 2?…”

A highly conductive porous graphene electrode prepared via in situ reduction of graphene oxide using Cu nanoparticles for the fabrication of high performance supercapacitors

“…XPS has been recognized as a powerful tool in atomic and element analysis. [44][45][46] The XPS spectrum of GO exhibited a high atomic ratio of carbon and oxygen (C/O) of 1.33. The spectrum can be divided into five different peaks centered at 284.5, 285.4, 286.6, 287.8, and 288.8 eV, which can be attributed to C=C, C-C, C-O, C=O, and O-C=O groups, respectively.…”

Bacterial cellulose in the field of wound healing and regenerative medicine of skin: recent trends and future prospectives

“…It occurs naturally in plant and animal tissues where it participates in a number of important roles. To certain limits, the human body has mechanisms available for protection against copper toxicity at the cellular, tissue, and organ levels [99,100]. It has been reported that copper nanoparticles have bactericidal effects comparable to silver nanoparticles in single strains of E. coli and B. subtilis [101].…”