Nanotubes, Carbon ; adverse effects ; chemistry

Carbon nanotube (CNT) is an important class of artificial nanomaterials with diverse potentials of nanobiomedical application. Before being introduced into bio-systems, it is necessary to explore the behavior and fate of CNTs in cells. However, limited understandings or information has been currently obtained in this realm, even some experimental results from different labs are conflicted. In this review, we focused on the location of CNTs in various cells as well as on the mechanisms of CNTs crossing the cell membranes. On the basis of data analysis shown by the current literatures, it was suggested that CNTs could enter cell's nucleus in certain conditions. Endocytosis and diffusion both exist; however, in some cases, one of them exhibited as major path, while the other one was not detectable because of the challenge resulting from the complex biological environments. The obstacles to powerful and standard characterizations of CNTs have also been discussed.
Cells ; metabolism ; Diffusion ; Endocytosis ; Nanotubes, Carbon ; chemistry

In recent years, multi-walled carbon nanotubes (MWCTs) are very favorable to the adsorption of middle molecular substances in the hemoperfusion because of their multiporous structure, large surface area and high reactivity, which are beneficial to the excellent absorption properties. The purpose of this study was to study the MWCTs on the adsorption capacity of the middle molecular substances. Vitamin B12 (VB12) was selected as a model of the middle molecular substances. The morphologies of MWCTs and activated carbon from commercial "carbon kidney" were observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The adsorption behavior of VB12 was compared to each other with UV-visible absorption spectra. The MWCTs formed a sophistaicate gap structure, and compared to the activated carbon, MWCTs had a larger surface area. By Langmuir equation and Freundlich equation fitting analysis, VB12 adsorption on MWCTs is fit for multi-molecular layer adsorption, and the adsorption type of activated carbon is more inclined to the model corresponding to Langmuir monolayer adsorption. The adsorption rate of MWCTs is faster than that of the activated carbon and the adsorption capacity is greater, which could be expected to become the new adsorbent in the hemoperfusion.
Adsorption ; Charcoal ; chemistry ; Nanotubes, Carbon ; chemistry ; Porosity ; Toxins, Biological ; chemistry ; Vitamin B 12 ; chemistry

In this study, the adsorption behavior of epirubicin hydrochloride (EPI) on carboxylated single-walled carbon nanotubes (c-SWNTs) obtained by mixture acid treatment was investigated. The results indicated that the dispersion of c-SWNTs in water was obviously improved. The absorption of EPI on c-SWNTs came to equilibrium after 240 min and could be explained by pseudo-second-order model. Moreover, there were heterogeneous distribution of active sites onto c-SWNTs surface and the Freundlich isotherm model was better fit to describe the absorption precess of EPI on c-SWNTs. The absorption capacity of EPI on c-SWNTs increased obviously with the increasing pH and decreasing temperature. Compared with multi-walled carbon nanotubes, carboxylated multi-walled carbon nanotubes, SWNTs, c-SWNTs possessed higher absorption capacity for EPI. The controlled, targeted and sustained release of EPI from c-SWNTs-EPI could be instructive for the development of nano-carrier.
Adsorption ; Antibiotics, Antineoplastic ; chemistry ; Carboxylic Acids ; chemistry ; Drug Carriers ; Epirubicin ; chemistry ; Nanotubes, Carbon ; chemistry

AIMTo simulate the inhalation of the C21H27NO and C29H41NO4 molecules, the effective components of methadone and buprenorphine, into carbon nanotubes, and discuss the feasibility of the loading of methadone and buprenorphine into carbon nanotubes.

METHODSThe MM + force-field based molecular dynamics (MD) method uas used.

RESULTSThe ends-opened carbon nanotubes with diameter larger than 1 or 1.25 nm can initiatively inhale the C21H27 NO or C29H41NO4 molecule, and both two molecules have higher potential energy at the open ends of the carbon tubes than that at the middle of the tubes; the present single-walled nanotubes are very suitable for the loading of methadone and buprenorphine.

CONCLUSIONIt is possible to make sustained-release detoxification agents with methadone- or buprenorphine-loaded carbon nanotubes.

Buprenorphine ; chemistry ; Computer Simulation ; Methadone ; chemistry ; Models, Molecular ; Molecular Structure ; Nanotubes, Carbon ; chemistry ; Narcotic Antagonists ; chemistry

Single walled carbon nanotubes (SWNT) have attracted increasing research interests for the purpose of biomedical application because they provide not only nanostructured topography, but also chemical composition of pure carbon atoms, as well as ultra high strength and excellent flexibility. Regarding the interactions of nanomaterials to biological systems, non-specific adsorption of plasma proteins is one of the most important issues to be concerned, which plays a crucial role that would determine how biological systems response to the biomaterials. Motivated by application of SWNT materials in biomedical fields, in this study, the adsorption behaviors of plasma proteins on the surface of SWNT nonwoven, prepared directly by floating chemical vapor observation and energy deposition method were investigated by means of scanning electron microscope (SEM), dispersive X-ray (EDX) analysis and ELISA. Results indicated the SWNT non-woven showed a clear adsorption preference of fibrinogen over albumin. There was no human serum albumin detected using above analysis methods on the SWNT nonwoven even incubated in the albumin solution of 4 mg/ml. While more than 0.15 microg of human fibrinogen was detected by ELISA on the SWNT nonwoven with area of 40 mm x 40 mm incubated in the fibrinogen solution of 5 microg/ml. In addition, IgG of sheep-anti-human serum fibrinogen exhibited strong nonspecific adsorption on the surface of SWNT nonwoven. The adsorption behaviors are different significantly from those of other carbon materials and conventional biomaterials. The unique interaction of SWNT nonwoven to plasma proteins is of significance to further studies of blood cells responses.
Adsorption ; Biocompatible Materials ; chemistry ; Blood Proteins ; chemistry ; Nanotubes, Carbon ; chemistry ; Surface Properties

In this paper, the new carbon nanotube modified glassy carbon electrode (F-CNTs/GCE) was prepared to establish a new method for studying the molecular interaction mechanism between baicalin metal complexes (BMC) and bovine serum album (BSA), and the principle of this method was discussed deeply. Under the physiological condition, the thermodynamics and kinetics properties of interaction between BMC and BSA were studied by cyclic voltammetry (CV) to inference their molecular effective mechanism. The results show that the presence of F-CNTs can accelerate the electron transfer, and better response signal was showed in the BMC/BMC-BSA system. The detection of interaction of BMC-BSA used new method show that BMC-BSA generates stable thermodynamically non-covalent compounds, and the obtained average binding sites of BMC-BSA were 1.7; the number of electron transfer in BMC/BMC-BSA reaction process was 2, and non electroactive supramolecular compounds of BMC-BSA were generated by this interacting reaction. The relevant research work provides a new way to study the molecular mechanism for the interaction of drugs with protein, and with a certain reference value for discussion on the non covalent interactions.
Animals ; Cattle ; Coordination Complexes ; chemistry ; Electrodes ; Flavonoids ; chemistry ; Kinetics ; Nanotubes, Carbon ; Serum Albumin, Bovine ; chemistry ; Thermodynamics

A sensitive electrochemical biosensor based on Aflatoxin-Oxidase (AFO) was developed for detection of sterigmatocystin (ST). The enzyme was immobilized on chitosan-single-walled carbon nanotubes (CS-SWCNTs) hybrid film, which attached to the poly-o-phenylenediamine (POPD)-modified Au electrode. The fabricated procedures of the biosensor were characterized with atomic force microscopy (AFM), fourier transform-infrared spectroscopy (FT-IR), and electrochemical impedance spectroscopy (EIS). The cyclic voltammetric results of the biosensor indicated that AFO exhibited a surface-controlled and quasi-reversible electrochemical redox behavior with a formal potential of -0.436 V (vs. Ag/AgCl) in 0.1 mol/L PBS (pH 7.0), which resulted from the direct electron transfer between entrapped AFO and the underlying electrode. The enzymatic electrode exhibited an excellent electrocatalytic response to ST. The linear range of ST determination was from 10 ng/mL to 310 ng/mL with correlation coefficient of 0.997, the detection limit was 3 ng/mL (S/N=3), and the response time was less than 10 seconds. The apparent Michaelis-Menten constant (K(M)app) was estimated to be 7.13 micromol/L. The biosensor had the advantages of good repeatability and stability, remaining 85.6% of its original current value after storage at 4 degrees C for a month, and the RSD for 11 replicate determination of 20 ng/mL ST was 3.9%. This AFO/CS-SWCNTs/POPD/Au modified electrode showed high selectivity and sensitivity in real sample analysis, giving values of recovery in the range of 87.6%-105.5%. The proposed method can be applied to the determination of ST in real samples with satisfactory results.
Aflatoxins ; Biosensing Techniques ; methods ; Chitosan ; chemistry ; Electrons ; Nanotubes, Carbon ; Oxidation-Reduction ; Oxidoreductases ; Phenylenediamines ; chemistry ; Sterigmatocystin ; analysis

Research and development of new drug carriers are crucial to the research of drugs. Due to their unique hollow structure and nano-diameter, carbon nanotubes (CNTs) can be used as drug carriers. Functionalization of CNTs with peptides, proteins, nucleic acids or even drug molecules, the so obtained functionalized CNTs can be used as carriers to deliver bioactive molecules into cells without causing any toxicity. The research progress of CNTs as drug carriers in recent years is summarized, and the CNTs' cytotoxicity and their ability to penetrate cells are discussed, and the methods of functionalizing carbon nanotubes are also mentioned in the paper. Along with the advancement of CNTs in drug carriers system, the relationship between the way to functionalize CNTs and the so obtained modified CNTs' ability to penetrate into cells, including the effect of dimension, should be further studied. Preparation of functionalized CNTs with high solubility and low toxicity as drug carriers will be the main research areas in the near future.
Animals ; Biocompatible Materials ; Drug Carriers ; chemistry ; Drug Design ; Genetic Vectors ; Humans ; Nanotubes, Carbon ; chemistry ; Solubility

With the emergence of avian flu, influence A virus and other diseases, the development of rapid, real-time, label-free biological sensors has become increasingly significant at the early detection and clinical diagnoses of various diseases. Single-walled carbon nanotubes (SWNTs) have unique one-dimensional structure, special electrical properties, good biocompatibility and size compatibility, so that the SWNTs have great potential uses in the biosensor fields due to these advantages. This article reviews recent examples of carbon nanotubes field-effect transistor (CNTFET) as a label-free biosensors for detecting a variety of biological macromolecules, such as protein, enzyme, DNA, cancer, virus, carbohydrate and so on.
Animals ; Biosensing Techniques ; instrumentation ; trends ; DNA ; chemistry ; Humans ; Nanotubes, Carbon ; chemistry ; Proteins ; analysis ; Transistors, Electronic