Antibacterial Cellulose Nanopapers via Aminosilane Grafting in Supercritical Carbon Dioxide

Abstract

In this work, we present an innovative strategy for the grafting of an antibacterial agent onto nanocellulose materials in supercritical carbon dioxide (scCO 2 ). Dense cellulose nanofibril (CNF) nanopapers were prepared and subsequently functionalized in supercritical carbon dioxide with an aminosilane, N-(6-aminohexyl)aminopropyltrimethoxysilane (AHA-P-TMS). Surface characterization (X-ray photoelectron spectroscopy, contact angle, zeta potential analysis) evidenced the presence of the aminosilane. Results show that the silane conformation depends on the curing process: a non-polycondensed conformation of grafted silane with the amino groups facing outwards was favored by curing in an oven while the curing step performed 2 in scCO 2 yielded CNF structures with the alkyl chain facing outwards. The grafted nanopapers exhibited antibacterial activity and no antibacterial agent was released into the media. Furthermore, these materials proved to benefit from a low cytotoxicity. This study offers a proof of concept for the covalent grafting of active species on nanocellulose structures and the control of aminosilane orientation using a green and controlled approach. These newly designed materials could be used for their antibacterial activity in the biomedical field. Thus, perspectives for topical administration and design of wound dressing could be envisaged.

Functional Modification of Cellulose Acetate Microfiltration Membranes by Supercritical Solvent Impregnation

“…The faster impregnation at the higher pressure is the consequence of the thymol solubility in scCO 2 increase with pressure [ 20 ] and interactions between the polymer and thymol. Namely, the pressure increase leads to the rise in scCO 2 density and, consequently, enhances its solvating power.…”

“…The peak at 1741 cm −1 is ascribed to the stretching mode of the C=O group [ 11 , 25 , 26 , 27 , 28 , 29 ]. The bands at 1433, 1367, and 1219 cm −1 are assigned to the C-H bending, rocking, and wagging vibrations, respectively [ 11 , 18 , 20 ]. The peak at 1036 cm −1 originates from C-O-C (ether linkage) from the glycosidic unit, while the peak at 901 cm −1 is a characteristic of saccharide [ 11 , 24 , 26 , 27 ].…”

“…Achoundong et al [ 19 ] reported the modification of CA films aimed for gas separation via grafting of vinyltrimethoxysilane to hydroxyl groups of CA, with subsequent condensation of hydrolyzed methoxy groups on the silane to form a polymer network. Although the grafting was performed to enhance the membranes’ selectivity in gas separations, silanization, especially by aminosilanes, may also be used to add antibacterial properties to the material [ 20 ].…”

A Review on Cellulose-based Materials for Biomedicine

“…Cellulose modified with aminoalkyl functional groups exhibit antibacterial activity [118,[127][128][129][130]. The modification takes place via the reaction with silanol groups as coupling agents.…”

Cellulose Acetate Membranes Modification by Aminosilane Grafting in Supercritical Carbon Dioxide towards Antibiofilm Properties

“…Generally, in the reported studies, monomer grafting was performed to reduce the interaction between 2 of 16 undesirable solutes and particulates with the surface, introduce suitable charged groups to create electrostatic repulsion from the membrane surface, or improve hydrophilicity for better surface-water interaction [7][8][9]. There are several reports on using ethoxy or methoxy silanes for grafting purposes, where hydroxyl groups at the surface of the solid phase were needed for the grafting reaction [10][11][12]. He et al reported bacterial cellulose grafting by 3-aminopropyltriethoxysilane as a method to produce membranes with antibiofilm properties for biomedical applications [10].…”