Enhanced antibacterial activity of a novel biocompatible triarylmethane based ionic liquid-graphene oxide nanocomposite

Biofilm formation on medical implants and devices has been a severe concern that results in their impaired performance and life-threatening complications. Thus, development of novel functional coatings for infection prone surfaces with biofilm inhibiting characteristics is of prime significance considering the rapid emergence of multidrug resistant bacteria. Herein we present a novel nanocomposite derived from Graphene Oxide (GO) and a newly developed functional Ionic liquid (IL) obtained through a metathesis reaction between a triarylmethane dye hexamethyl pararosaniline chloride or crystal violet (CV) and sodium dodeceyl sulfate (SDS) to yield [CV][DS] (hexamethyl pararosaniline dodecyl sulfate). This highly biocompatible [CV][DS]-GO nanocomposite exhibit more than four times improved antibacterial activity in comparison to bare GO against both gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus). As suggested by XRD, FTIR and UV absorption and SEM results improved activity of [CV][DS]-GO nanocomposite is ascribed to the synergistic effect of reduced nanocomposite sheet thickness, enhanced amphiphilicity imparted by dodecylsulfate (DS), exposed active ArN⁺ groups of CV and some inherent functionalities of GO. This is also complemented by the ruptured and diffused S. aureus cell walls as observed in bacterial SEM result. In contrast, the nanocomposites of the precursors with GO do not demonstrate any significant antibacterial effect. Coatings developed using GO upon infestation with E. coli revealed significant biofilm formation after 48 and 72 h of incubation while [CV][DS]-GO coated surface demonstrated no colony growth under similar circumstances. Thus, [CV][DS]-GO nanocomposite coatings exhibit excellent resistance to bacterial growth even up to 72 h incubation signifying its bactericidal effect. Therefore, the developed nanocomposite may be considered as one of the improved antibacterial wash resistant coating material for biomedical devices and surfaces susceptible to to biofilm formation.

Metal Phthalocyanines as Catalyst Precursors of Metallated Carbon Nanotubes

BACKGROUND

The addition of nanoparticles to cellulose paper can improve its mechanical strength, chemical stability, biocompatibility and hydrophobic properties. Silica nanoparticles are known to be inert, hydrophobic, biocompatible, biodegradable and have a good distribution being deposited on surfaces. The main characteristics of 20 nm SiO2 nanoparticles are good chemical and thermal stability with a melting point of 1610-1728°C, a boiling point of 2230°C with a purity of 99.5%.

OBJECTIVE

To carry out the hydrophobization of paper based on Kraft cellulose and on cellulose obtained from soybean husk with 20-nm size SiO2 nanoparticles and to study hydrophobicity, morphology and topography of the prepared composites. Few relevant patents to the topic have been reviewed and cited.

METHODS

The ground and roasted soybean husk was treated with a NaOH, washed and dried. Hydrophobization of paper was carried in aqueous medium by SiO2 addition in weight ratios "paper-SiO2 " of 0.01-0.05 wt.%, stirring, filtration and drying. The obtained cellulose sheet composites were characterized by Scanning Electron Microscopy (SEM), Transmisión Electron Microscopy (TEM), FTIRspectroscopy, Mullen proofs of hydrophobicity, and contact angle measurements.

RESULTS

The mechanical properties of paper nanocomposites (tensile strength and compression) increased considerably by varying the concentrations. The tensile strength increased by 41-46% and the compressive strength increased by 55-56%. The existence of fiber nanofoils, good adhesion of 20-nm SiO2 nanoparticles to the paper surface, and their homogeneous distribution were observed.

CONCLUSION

Cellulose was successfully obtained from soybean husk, applying the alkaline-based extraction method. A good reinforcement of cellulose fibers is observed due to the outstanding characteristics of the silicon dioxide nanoparticles.