Diana Haase

Carbon nanotubes filled with a chemotherapeutic agent: a nanocarrier mediates inhibition of tumor cell growth

AIM In this paper, carbon nanotubes (CNTs) are presented as feasible carriers for carboplatin, a therapeutic agent for cancer treatment. The drug was introduced into CNTs to demonstrate that they are suited as nanocontainers and nanocarriers and can release the drug to initialize its medical virtue. METHOD The filling was accomplished by a wet-chemical approach after the CNTs were opened. The effect on cell proliferation and cytotoxicity of the carboplatin-filled CNT was investigated by using a viability assays. RESULTS Using different analysis methods such as electron energy loss spectroscopy and x-ray photoelectron spectroscopy the structure of carboplatin incorporated into the CNTs was found to be retained. In vitro studies showed that carboplatin-filled CNTs inhibited growth of bladder cancer cells whereas unfilled, opened CNTs barely affected cancer cell growth. CONCLUSION A reversible filling-emptying process could be performed successfully within this work. This highlights the potential of CNTs for applications in the field of drug delivery.

Delivery of carboplatin by carbon-based nanocontainers mediates increased cancer cell death

Since the activity of several conventional anticancer drugs is restricted by resistance mechanisms and dose-limiting side-effects, the design of nanocarriers seems to be an efficient and promising approach for drug delivery. Their chemical and mechanical stability and their possible multifunctionality render tubular nanomaterials, such as carbon nanotubes (CNTs) and carbon nanofibres (CNFs), promising delivery agents for anticancer drugs. The goal of the present study was to investigate CNTs and CNFs in order to deliver carboplatin in vitro. No significant intrinsic toxicity of unloaded materials was found, confirming their biocompatibility. Carboplatin was loaded onto CNTs and CNFs, revealing a loading yield of 0.20 mg (CNT-CP) and 0.13 mg (CNF-CP) platinum per milligram of material. The platinum release depended on the carrier material. Whereas CNF-CP marginally released the drug, CNT-CP functioned as a drug depot, constantly releasing up to 68% within 14 days. The cytotoxicity of CNT-CP and CNF-CP in urological tumour cell lines was dependent on the drug release. CNT-CP was identified to be more effective than CNF-CP concerning the impairment of proliferation and clonogenic survival of tumour cells. Moreover, carboplatin, which was delivered by CNT-CP, exhibited a higher anticancer activity than free carboplatin.

A carbon-wrapped nanoscaled thermometer for temperature control in biological environments

AIMS A carbon-wrapped nanoscaled thermometer for a contactless temperature control in biological systems on the cellular level is presented. MATERIALS & METHODS The thermometer is based on multiwalled carbon nanotubes (MWCNTs) filled with materials with strongly temperature-dependent nuclear magnetic resonance (NMR) parameters. The NMR frequency shift and relaxation time were measured in cuprous-iodide-filled CNTs at different temperatures. RESULTS The experimental data indicate a pronounced temperature dependence of the NMR parameters, thereby realizing the nanoscaled thermometer. CONCLUSION This study is a proof-of-concept that the functionalized CNTs can be used as a contactless thermometer in biomedical applications.

Novel carbon nanotube composites by grafting reaction with water-compatible redox initiator system

Multi-walled carbon nanotubes were chemically functionalized with methacrylic acid and methacrylated bovine serum albumin by free radical grafting reaction to obtain novel nanocomposites. The nanotubes were synthesized by aerosol-assisted chemical vapor deposition, and then the monomers were directly grafted by the action of hydrogen peroxide/ascorbic acid redox pair which allows operating in water-compatible and eco-friendly environment without the generation of any toxic reaction by-product. A multi-technique approach was used to evaluate the effectiveness of the grafting process employing Fourier transform infrared, Raman, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and thermogravimetric analyses. Considering the high importance of methacrylate polymers and bovine serum albumin, the proposed nanocomposites could be of great applicability in biomedical and pharmaceutical fields.

Carbon Nanotubes Filled with Carboplatin: Towards Carbon Nanotube-Supported Delivery of Chemotherapeutic Agents

Thanks to their capillary-like structure CNTs provide a well-characterized container material for hosting miscellaneous fillings. Here we present basic studies on the use of CNTs for drug delivery. By introducing carboplatin, an anticancer drug, into the CNTs via a wet chemical approach, drug-filled nanotubes have been produced. The maintenance of the structure of carboplatin was proven using electron energy loss spectroscopy and X-ray photoelectron spectroscopy. It was shown that the drug is released into cell culture medium leading to cell death. Cell viability assays performed with bladder cancer cells EJ28 demonstrated the cytotoxicity of CNTs filled with carboplatin. For comparison a reference of unfilled, open ended CNTs did not affect the cell viability. These results point out the general capabilities of CNTs as nanocarriers for drug delivery.

Carbon Nanotubes – Imprinted Polymers: Hybrid Materials for Analytical Applications

Molecular imprinting is a recent new and rapidly evolving technique which allows the creation of synthetic receptors (MIPs) consisting of highly cross-linked porous-rich polymers with recognition properties comparable to the biological systems related to the presence of specific recognition sites complementary in shape, size and functional groups to a target molecule. It is a facile concept, which involves the construction of sites of specific recognition, commonly within synthetic polymers. The template of choice is entrapped within a pre-polymerization complex, consisting of functional monomers with good functionality, which chemically interacts with the template. Polymerization in the presence of crosslinker serves to freeze these template-monomer interactions and subsequent removal of the template results in the formation of a molecularly imprinted polymer matrix. Due to the advantages of MIPs such as low cost, stability, and easy preparation compared with natural molecular recognition products (e.g. antibody), Molecular imprinting is a welldeveloped tool in the analytical field, mainly for separating and quantifying very different substances, including drugs and bio-active molecules contained in relatively complex matrices. Despite the application of MIPs as sensor matrices or separation materials, they suffer from basic limitations associated with the limited concentration of imprinted sites, and the bulk volume of the polymer matrices that requires long diffusion paths of the imprinted host molecules. These limitations lead to inefficient sensing or separation processes. MIP nanomaterials are proposed as a pain reliever for headache by improving the accessibility and the homogeneity of the binding sites. In particular, with high strength, the extremely large surface area and unique chemical properties, Carbon nanotubes (CNTs) could serve as the reinforcing element or core in fabricating core–shell structural MIPs.