Synthesis and synergistic antibacterial efficiency of chitosan-copper oxide nanocomposites
Jüri Laanoja,
Mariliis Sihtmäe,
Svetlana Vihodceva,
Mairis Iesalnieks,
Maarja Otsus,
Imbi Kurvet,
Anne Kahru,
Kaja Kasemets
Affiliations
Jüri Laanoja
Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia; Department of Chemistry and Biotechnology, School of Science, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia
Mariliis Sihtmäe
Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia
Svetlana Vihodceva
Institute of Materials and Surface Engineering, Faculty of Natural Sciences and Technology, Riga Technical University, Paula Valdena 3/7, LV-1048 Riga, Latvia
Mairis Iesalnieks
Institute of Materials and Surface Engineering, Faculty of Natural Sciences and Technology, Riga Technical University, Paula Valdena 3/7, LV-1048 Riga, Latvia
Maarja Otsus
Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia
Imbi Kurvet
Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia
Anne Kahru
Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia; Estonian Academy of Sciences, Kohtu 6, 10130 Tallinn, Estonia
Kaja Kasemets
Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia; Corresponding author.
Copper and chitosan are used for biomedical applications due to their antimicrobial properties. In this study, a facile method for the synthesis of chitosan-copper oxide nanocomposites (nCuO-CSs) was modified, yielding stable colloidal nCuO-CSs suspensions. Using this method, nCuO-CSs with different copper-to-chitosan (50–190 kDa) weight ratios (1:0.3, 1:1, 1:3) were synthesized, their physicochemical properties characterized, and antibacterial efficacy assessed against Gram-negative Escherichia coli and Pseudomonas aeruginosa, and Gram-positive Staphylococcus aureus. The nCuO-CSs with a primary size of ∼10 nm and a ζ-potential of >+40 mV proved efficient antibacterials, acting at concentrations around 1 mg Cu/L. Notably, against Gram-negative bacteria, this inhibitory effect was already evident after a 1-h exposure and surpassed that of copper ions, implying to a synergistic effect of chitosan and nano-CuO. Indeed, using flow cytometry and confocal laser scanning microscopy, we showed that chitosan promoted interaction between the nCuO-CSs and bacterial cells, facilitating the shedding of copper ions in the close vicinity of the cell surface. The synergy between copper and chitosan makes these nanomaterials promising for biomedical applications (e.g., wound dressings).
