Adsorption and encapsulation of melittin on covalently functionalized carbon nanotubes; a molecular dynamics simulation study

For the first time, molecular dynamics (MD) simulation was used to examine melittin's adsorption and encapsulation on covalently functionalized carbon nanotubes (fCNTs). The CNT wall and terminals were functionalized with carboxy, hydroxyl, and amine functional groups. The findings demonstrated that the melittin would be adsorbed on the fCNT's outer surface when just the CNT terminal is functionalized. On the other hand, melittin is encapsulated inside the nanotube space when the CNTs' walls and terminals are functionalized. Encapsulated melittin has an alpha-helix structure similar to melittin in a water medium. With the use of parameters like root mean square fluctuations (RMSF) and radius of gyration (Rg), the melittin conformational changes were evaluated. According to the findings, the amine functional group significantly alters the melittin's conformation. The wall and terminals fCNTs with hydroxyl and carboxyl could encapsulate melittin inside them with a stable structure. This result will be useful for the design of peptide carriers.

Investigation of the Pristine and Functionalized Carbon Nanotubes as a Delivery System for the Anticancer Drug Dacarbazine: Drug Encapsulation

Carbon Nanotubes (CNTs) have been used as the systems in drug delivery due to their exceptional physical and chemical properties. In this study, the adsorption of an anticancer drug Dacarbazine (DAC) into the inner and outer surface of pristine and Functionalized Carbon Nanotubes (FCNTs) with four carboxylic acid groups was investigated in aqueous solution using the Molecular Dynamics (MD) simulations. Our simulation results showed that in spite of the adsorption of drug molecules on the outer sidewall of pristine and functionalized nanotubes, the spontaneous encapsulation of DAC molecule into the cavity of CNTs and FCNTs is observed. The simulations show that the arrangement of the DAC molecule into the CNTs and FCNTs is controlled by π-π interactions.

Flow-electrode capacitive deionization with highly enhanced salt removal performance utilizing high-aspect ratio functionalized carbon nanotubes

Flow-electrode-based capacitive deionization (FCDI) has attracted much attention owing to its continuous and scalable desalination process without the need for a discharging step, which is required in conventional fixed-electrode capacitive deionization. However, flow electrode slurry is poorly conductive, which restricts desalination performance, but higher carbon mass loading in the slurry could improve salt removal capacity due to enhanced connectivity. However, increased viscosity restricts higher loading of active materials. Herein, we report a significant increase in salt removal performance by introducing functionalized carbon nanotubes (FCNTs) into activated carbon (AC)-based flow electrodes, which led to the generation of conducting bridges between AC particles. The salt removal rate in the presence of 0.25 wt% FCNT with 5 wt% AC improved four-fold from that obtained with only 5 wt% AC, which is the highest value reported in the literature so far (from 1.45 to 5.72 mmol/m²s, at a saline water concentration of 35.0 g/L and applied potential of 1.2 V). Further, FCNTs with a high aspect ratio (∼50,000) can more effectively enhance salt removal than low-aspect ratio FCNTs (∼1300). Electrochemical analysis further confirms that the addition of FCNTs can efficiently form a connecting percolation network, thus enhancing the conductivity of the flow electrode slurry for the practical application of highly efficient desalination systems.

Effect of carbon nanotube (CNT) functionalization in Epoxy-CNT composites

The effect of carbon nanotube (CNT) functionalization in altering the properties of Epoxy-CNT composites is presented. The presence of functional groups effectively influenced the colloidal behavior of CNTs in the precursor epoxy resin and the hardener triethylenetetramine (TETA), which affected the synthesis process and eventually the interfacial interactions between the polymer matrix and the CNTs. The physical, thermal and electrical properties of the composites exhibited strong dependence on the nature of functionalization. At a 0.5 wt% CNTs loading, the enhancement in tensile strength was found to be 7.2, 11.2, 11.4 and 14.2 percent for raw CNTs, carboxylated CNTs, octadecyl amide functionalized CNTs and hydroxylated CNTs, respectively. Glass transition temperatures (T_g) also varied with the functionalization and composite prepared using hydroxylated CNTs showed the maximum enhancement of 34%.

Gene Delivery to Tobacco Root Cells with Single-Walled Carbon Nanotubes and Cell-Penetrating Fusogenic Peptides

Development of efficient, easy, and safe gene delivery methods is of great interest in the field of plant biotechnology. Considering the limitations of the usual transfection methods (such as transgene size and plant type), several new techniques have been tested for replacement. The success of some biological and synthetic nanostructures such as cell-penetrating peptides and carbon nanotubes in transferring macromolecules (proteins and nucleic acids) into mammalian cells provoked us to assess the ability of an engineered chimeric peptide and also arginine functionalized single-walled carbon nanotube in gene delivery to intact tobacco (Nicotiana tabacum var. Virginia) root cells. It was suggested that the engineered peptide with its special cationic and hydrophobic domains and the arginine functionalized single-walled carbon nanotube due to its nano-cylindrical shape can pass plant cell barriers while plasmid DNA (which codes green fluorescent protein) has been condensed on them. The success of gene delivery to tobacco root cells was confirmed by fluorescence microscopy and western blotting analysis.

The functionalization of carbon nanotubes to enhance the efficacy of the anticancer drug paclitaxel: a molecular dynamics simulation study

Carbon nanotubes (CNTs) are widely used in drug delivery systems (DDSs) due to their unique chemical and physical properties. Investigation of interactions between biomolecules and CNTs is an interesting and important subject in biological applications. In this study, we used molecular dynamics (MD) simulation to investigate the adsorption mechanism of the anticancer drug paclitaxel (PTX) on pristine and functionalized CNTs (f-CNT) in aqueous solutions. Our theoretical results show that PTX can be adsorbed on sidewalls of CNT in different methods. In the case of f-CNTs, PTX can be adsorbed on the functional groups due to the existence of polar interactions. These interactions in the CNT functionalized with polyethylene glycol (PEG), are more than the other investigated systems. Furthermore, it was found that the solubility of CNTs in aqueous solution is increased by functionalization. This is related to the intermolecular hydrogen bonds between functional groups and solvent molecules. The PEG group has the greatest effect on the solubility of the CNT in aqueous solution due to more polar interactions.