Functionalized Carbon Nanomaterials Research Articles

Carbon Nanomaterials for Drug Delivery

Carbon Nanotubes (CNTs) and Graphene Have Attracted Tremendous Attention as the Most Promising Carbon Nanomaterials in the 21st Century for a Variety of Applications such as Electronics, Biomedical Engineering, Tissue Engineering, Neuroengineering, Gene Therapy and Biosensor Technology. For the Biomedical Applications, Cnts Have Been Utilized over Existing Drug Delivery Vectors due to their Ability to Cross Cell Membranes Easily and their High Aspect Ratio as Well as High Surface Area, which Provides Multiple Attachment Sites for Drug Targeting. Besides, it Has Also Been Proved that the Functionalization of CNTs May Remarkably Reduce their Cytotoxic Effects and at the Same Time Increase their Biocompatibility. So, the Functionalized CNTs Are Safer than Pristine or Purified CNTs, Thus Offering the Potential Exploitation of Nanotubes for Drug Administration. On the other Hand, More Recently Graphene and its Derivatives Have Been Enormously Investigated in the Biological Applications because of their Biocompatibility, Unique Conjugated Structure, Relatively Low Cost and Availability on both Sides of a Single Sheet for Drug Binding. In Our Study, we Have Covalently Functionalized Multiwalled Carbon Nanotubes (MWCNTs) and Graphene Oxide (GO) with Highly Hydrophilic and Biocompatible Excipients in Order to Increase their Aqueous Solubility and Biocompatibility. Various Excipients Used Were Polyvinyl Alcohol, Pluronic F38, Tween 80 and Maltodextrin. The Poorly Water-Soluble Anticancer Drugs such as, Camptothecin and Ellagic Acid, Were Loaded onto the Functionalized MWCNTs and GO via Non-Covalent Interactions. Furthermore, Drug Loading and Cytotoxic Activity of Drugs Incorporated with the Functionalized MWCNTs and GO as Nanocarriers Were Also Investigated. Drugs Loaded on both Carbon Nanocarriers Exhibited a Higher Cytotoxic Activity than Free Drug. On the other Hand, No Significant Toxicity Was Found even at Higher Concentrations when the Cells Were Incubated with the Functionalized Mwcnts and GO. Therefore, both these Functionalized Carbon Nanomaterials Are Ideal Carriers for Drug Delivery.

Polyacrylonitrile/polybenzoxazine-based Fe3O4@carbon nanofibers: hierarchical porous structure and magnetic adsorption property

Hierarchical porous, magnetic Fe3O4@carbon nanofibers (Fe3O4@CNFs) comprising graphitic nanofibers and embedded Fe3O4 nanocrystals were prepared by using electrospun polyacrylonitrile/polybenzoxazine (PBZ) nanofibers as composite carbon precursor. By the combination of precursor design and activation process, a series of Fe3O4@CNFs with a tunable porous structure including the surface area, pore volume and micro/mesopore ratio were obtained, and could achieve an extremely high surface area of 1623 m2 g−1 and a pore volume of 1.635 cm3 g−1. Quantitative pore size distribution and fractal analysis were employed to investigate the hierarchical porous structure using N2 adsorption methods and synchrotron radiation small-angle X-ray scattering measurements. The role of the precursor structure and activation treatment for the tuning of the porous structure and surface fractal dimension is discussed, and the relative fraction of closed and open pores in CNFs is confirmed. Furthermore, the as-prepared Fe3O4@CNFs exhibit efficient adsorption for organic dyes in water and excellent magnetic separation performance, which would make them a promising adsorbent for water treatment, and a new insight was also provided into the design and development of functional carbon nanomaterials based on PBZ precursor.

Investigation of the electrochemical behavior of dopamine at electrodes modified with ferrocene-filled double-walled carbon nanotubes

Electrochemical properties of a new class of endohedral functionalized carbon nanomaterial, ferrocene-filled double-walled carbon nanotubes (Fc@DWNTs) have been investigated by preparing an Fc@DWNTs modified glassy carbon electrode (Fc@DWNTs/GCE). In an aqueous LiClO4 solution, one pair of redox peaks corresponding to the surface-confined Fc+/Fc couple was observed, suggesting that Fc molecules encapsulated inside DWNTs retain their electrochemical activity. Moreover, the Fc@DWNTs/GCE showed good stability because DWNTs could overcome the leaching of Fc from the modified electrode. Electrocatalytic oxidation of dopamine (DA) at the Fc@DWNTs modified electrodes was also obtained, indicating that encapsulated Fc molecules can serve as good electron-transfer mediators. In addition, due to the peculiar structure of Fc@DWNTs, direct electroreduction of oxidation product of DA was also observed. An electrochemical sensor for DA has been constructed based on Fc@DWNTs and a kind of cation exchange membrane, Nafion, which played a key role in the selectivity of the sensor. Amperometric measurements were conducted in the presence of a large excess of ascorbic acid (AA). The limit of detection was found to be 0.3μM based on S/N of 3.

Functionalized carbon nanomaterials: exploring the interactions with Caco-2 cells for potential oral drug delivery

Although carbon nanomaterials (CNMs) have been increasingly studied for their biomedical applications, there is limited research on these novel materials for oral drug delivery. As such, this study aimed to explore the potential of CNMs in oral drug delivery, and the objectives were to evaluate CNM cytotoxicity and their abilities to modulate paracellular transport and the P-glycoprotein (P-gp) efflux pump. Three types of functionalized CNMs were studied, including polyhydroxy small-gap fullerenes (OH-fullerenes), carboxylic acid functionalized single-walled carbon nanotubes (f SWCNT-COOH) and poly(ethylene glycol) functionalized single-walled carbon nanotubes (f SWCNT-PEG), using the well-established Caco-2 cell monolayer to represent the intestinal epithelium. All three CNMs had minimum cytotoxicity on Caco-2 cells, as demonstrated through lactose dehydrogenase release and 3-(4,5-dimethyliazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Of the three CNMs, f SWCNT-COOH significantly reduced transepithelial electrical resistance and enhanced transport of Lucifer Yellow across the Caco-2 monolayer. Confocal fluorescence microscopy showed that f SWCNT-COOH treated cells had the highest perturbation in the distribution of ZO-1, a protein marker of tight junction, suggesting that f SWCNT-COOH could enhance paracellular permeability via disruption of tight junctions. This modulating effect of f SWCNT-COOH can be reversed over time. Furthermore, cellular accumulation of the P-gp substrate, rhodamine-123, was significantly increased in cells treated with f SWCNT-COOH, suggestive of P-gp inhibition. Of note, f SWCNT-PEG could increase rhodamine-123 accumulation without modifying the tight junction. Collectively, these results suggest that the functionalized CNMs could be useful as modulators for oral drug delivery, and the differential effects on the intestinal epithelium imparted by different types of CNMs would create unique opportunities for drug-specific oral delivery applications.

Functionalized carbon nanomaterials as nanocarriers for loading and delivery of a poorly water-soluble anticancer drug: a comparative study

Carbon nanomaterials such as multiwalled carbon nanotubes (MWCNTs) and graphene oxide (GO) have been functionalized by highly hydrophilic and biocompatible poly(vinyl alcohol) (PVA) for loading and delivery of an anticancer drug, camptothecin (CPT). For the first time, CPT was loaded onto MWCNT-PVA and GO-PVA through π-π interactions and its capability to kill human breast and skin cancer cells was investigated.

ChemInform Abstract: Functionalized Carbon Nanomaterials Derived from Carbohydrates

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High-performance biofuel cell made with hydrophilic ordered mesoporous carbon as electrode material

A highly hydrophilic ordered mesoporous carbon has been synthesized by a microwave assisted method from a mixture containing glucose and poly(vinyl alcohol) and with a silica template to have high hydrophilicity, low charge transfer resistance and large specific surface area. The new carbon material is further used as an electrode material to fabricate an anode-limited glucose/O 2 biofuel cell, which gives an output power density of 110 μW cm −2 with cell voltage of 0.72 V, a performance much higher than the reported anodes made from SWNT, bi-polymer layer and carbon black at the same or even higher glucose concentration. This work provides a universal approach to synthesize functional carbon nanomaterials with desired architectures and properties for various important applications in energy conversion systems such as fuel cells and solar cells.

Functionalized Carbon Nanomaterials Derived from Carbohydrates

A tremendous growth in the field of carbon nanomaterials has led to the emergence of carbon nanotubes, fullerenes, mesoporous carbon and more recently graphene. Some of these materials have found applications in electronics, sensors, catalysis, drug delivery, composites, and so forth. The high temperatures and hydrocarbon precursors involved in their synthesis usually yield highly inert graphitic surfaces. As some of the applications require functionalization of their inert graphitic surface with groups like -COOH, -OH, and -NH(2), treatment of these materials in oxidizing agents and concentrated acids become inevitable. More recent works have involved using precursors like carbohydrates to produce carbon nanostructures rich in functional groups in a single-step under hydrothermal conditions. These carbon nanostructures have already found many applications in composites, drug delivery, materials synthesis, and Li ion batteries. The review aims to highlight some of the recent developments in the application of carbohydrate derived carbon nanostructures and also provide an outlook of their future prospects.

Fibroblast cell behavior on chemically functionalized carbon nanomaterials

This paper describes the interaction of 3T3 fibroblast cells with chemically functionalized carbon nanomaterial substrates. Multiwall carbon nanotubes and carbon nanofibers were functionalized using acid treatment. A more hydrophilic surface was obtained by adding functional groups which are defects at the ends of the multi-walled carbon nanotubes and carbon nanofibers. 3T3 fibroblast cells were cultured on both as-grown and functionalized carbon nanomaterials on a glass slide. Visual differential interference contrast (DIC) images and fluorescent images of stained α, β tubulin showed the effectiveness of the functionalized nanomaterials as substrate materials. Good adhesion of the 3T3 fibroblast cells to the functionalized nanomaterials was verified and indicates that nanomaterials have potential for tissue scaffold development. No significant toxic effects of the nanomaterials on the 3T3 cells were observed. Possible explanations of why cells grow on nanomaterials are given.

Functionalization of carbon nanomaterials by evolutionary molecular engineering: Potential application in drug delivery systems

By virtue of the progress made in evolutionary molecular engineering, peptide aptamers that specifically recognize target molecules are now routinely created using a peptide phage display system. The system was originally developed for isolating peptides that specifically recognized biomacromolecules (e.g. proteinous receptors), but are now also being used to acquire peptide motifs that bind to inorganic materials, such as semiconductors, metals and carbon nanomaterials. We have created the peptide aptamer against carbon nanohorns, a vesicular carbon nanomaterial whose size is 80–100 nm in diameter. By combining the peptide motif that has affinity to the surfaces of carbon nanohorns with peptide aptamers that can target specific organs, we can functionalize the carbon nanomaterial to provide novel types of carriers for drug delivery systems.

MALDI Matrices for Biomolecular Analysis Based on Functionalized Carbon Nanomaterials

When used in small molar ratios of matrix to analyte, derivatized fullerenes and single wall nanotubes are shown to be efficient matrices for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The mixing of an acidic functionalized fullerene with a solution of bioanalyte, depositing a dried droplet, and irradiating with a pulsed nitrogen laser yields protonated or cationized molecular ions. Derivatized fullerenes could offer several advantages over conventional MALDI matrices: a high analyte ionization efficiency, a small molar ratios (less than 1) of matrix/analyte, and a broader optical absorption spectrum, which should obviate specific wavelength lasers for MALDI acquisitions. The major disadvantage to the use of fullerenes is the isobaric interference between matrix and analyte ions; however, it is overcome by using MALDI-ion mobility time-of-flight (IM-oTOF) mass spectrometry to preseparate carbon cluster ions from bioanalyte ions prior to TOF mass analysis. However, an alternative to the dried droplet preparation of fullerene MALDI samples is the aerosolization of matrix-analyte solutions (or slurries) followed by impacting the aerosol onto a stainless surface. We also demonstrate that the fullerene matrices can be used to acquire spectra from rat brain tissue.