Cytotoxicity Effects of Water-Soluble Multi-Walled Carbon Nanotubes Decorated with Quaternized Hyperbranched Poly(ethyleneimine) Derivatives on Autotrophic and Heterotrophic Gram-Negative Bacteria

Abstract

Oxidized multi-walled carbon nanotubes (oxCNTs) were functionalized by a simple non-covalent modification procedure using quaternized hyperbranched poly(ethyleneimine) derivatives (QPEIs), with various quaternization degrees. Structural characterization of these hybrids using a variety of techniques, revealed the successful and homogenous anchoring of QPEIs on the oxCNTs’ surface. Moreover, these hybrids efficiently dispersed in aqueous media, forming dispersions with excellent aqueous stability for over 12 months. Their cytotoxicity effect was investigated on two types of gram(−) bacteria, an autotrophic (cyanobacterium Synechococcus sp. PCC 7942) and a heterotrophic (bacterium Escherichia coli). An enhanced, dose-dependent antibacterial and anti-cyanobacterial activity against both tested organisms was observed, increasing with the quaternization degree. Remarkably, in the photosynthetic bacteria it was shown that the hybrid materials affect their photosynthetic apparatus by selective inhibition of the Photosystem-I electron transport activity. Cytotoxicity studies on a human prostate carcinoma DU145 cell line and 3T3 mouse fibroblasts revealed that all hybrids exhibit high cytocompatibility in the concentration range, in which they also exhibit both high antibacterial and anti-cyanobacterial activity. Thus, QPEI-functionalized oxCNTs can be very attractive candidates as antibacterial and anti-cyanobacterial agents that can be used for potential applications in the disinfection industry, as well as for the control of harmful cyanobacterial blooms.

Carbon Nanodisks Decorated with Guanidinylated Hyperbranched Polyethyleneimine Derivatives as Efficient Antibacterial Agents

“…It was found that, on average, 19.2 μmol (0.128 g) GPEI5K and 5.1 μmol (0.170 g) GPEI25K were attached to 1 g of oxCNDs@GPEI5K and oxCNDs@GPEI25K, respectively. Additionally, the quantification of the GPEI content was calculated using the nitrogen mass fraction in the final oxCNDs@GPEIs as the nitrogen signal mainly derives from GPEIs [ 35 , 36 , 52 ]. As presented in Table S3 , the actual value of the GPEI content in the final oxCNDs@GPEI5K and oxCNDs@GPEI25K was estimated at 13.63% w/w and 16.26% w/w , respectively, which are in line with the results obtained from 1 H NMR spectroscopy.…”

“…Another crucial parameter related to the enhanced antibacterial activity of oxCNDs@GPEIs is their improved aqueous dispersion compared to oxCNDs, which can facilitate their interaction with bacteria, resulting in greater cell damage. It is known that well-dispersed carbon-based materials, such as carbon nanotubes [ 36 ] or graphene oxide [ 16 ], can strongly interact with bacteria though direct contact, resulting in extended membrane damage.…”

“…The functionalization of oxCNDs with guanidinylated hyperbranched polyethyleneimine derivatives was performed following an analogous method previously described [ 35 , 36 ] In brief, 150 mg oxCNDs were dispersed in 50 mL distilled H 2 O with the aid of ultrasonication for 30 min, applying a Hielscher UP200S high intensity ultrasonic processor (Hielscher Ultrasonics GmbH, Teltow, Germany) coupled with a standard sonotrode (3 mm tip-diameter) at 50% amplitude and 0.5 cycles/s. Then, the pH value of the dispersion was adjusted to ~9 by the addition of NaOH solution (0.5 M) and left under stirring for 24 h, at room temperature.…”

Ultrasonic-Assisted Synthesis of Germanane and Siloxane Nanostructures

“…In last decades, carbon nanomaterials such as graphene and its derivatives, [1][2][3][4][5] nanotubes, [6] nanodots, [7] etc. have been actively studied due to their physicochemical properties making them ideal materials in many technological applications.…”

Special Issue “Novel Antibacterial Agents”

“…Functionalization of oxidized multi-walled carbon nanotubes (oxCNTs) was studied by Z. Sideratou et al [7], who used a simple non-covalent modification procedure, using hyperbranched poly(ethyleneimine) derivatives (QPEIs), with various quaternization degrees. The aqueous dispersion of this material was found to be stable over 12 months and to be provided with significant antibacterial and anti-cyanobacterial activity.…”