Biomedical subjects

Valery N Khabashesku

Publications and source records attributed to Valery N Khabashesku.

8 recordsLinked to original sources

PubMed2005

AFM and STM characterization of thiol and thiophene functionalized SWNTs: pitfalls in the use of chemical markers to determine the extent of sidewall functionalization in SWNTs.

Thiol- and thiophene-functionalized SWNTs prepared via the reaction of a substituted amine with fluoronanotubes show similar levels of sidewall functionalization, however, the use of Au nanoparticles as chemical markers for AFM gives misleading results for substituent distribution since STM shows the thiol substituents grouped in bands while the thiophene substituents uniformly distributed along the SWNTs.

Journal Article↗

PubMed2005

Diels-Alder addition to fluorinated single walled carbon nanotubes.

Fluorinated single walled carbon nanotubes (SWNTs) undergo a facile Diels-Alder [4 + 2] cycloaddition with a range of dienes resulting in a C ratio substituent ratio between 20 ratio 1 to 32 ratio 1; IR, Raman, AFM and (13)C NMR characterization are consistent with sidewall functionalization.

Journal Article↗

PubMed2005

Fluorinated nanodiamond as a wet chemistry precursor for diamond coatings covalently bonded to glass surface.

The chemical reaction between fluoro-nanodiamond (F-ND) powder, solubilized in o-dichlorobenzene, and a glass surface, functionalized with the silane coupling agent, 3-aminopropyltriethoxysilane (APTES), was found to proceed under heating at 130 degrees C for 24-40 h and to result in covalent bonding of F-ND particles to a glass substrate, forming a 10-40 nm thick nanocrystalline film. The observed process presents a novel and cost-effective approach to fabrication of diamond coatings on glass by using wet chemistry instead of CVD and can be extended to other materials.

Journal Article↗

PubMed2004

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.

Amino Acid Sequence↗

PubMed2003

Sidewall carboxylic acid functionalization of single-walled carbon nanotubes.

The reactions of single-walled carbon nanotubes (SWNTs) with succinic or glutaric acid acyl peroxides in o-dichlorobenzene at 80-90 degrees C resulted in the addition of 2-carboxyethyl or 3-carboxypropyl groups, respectively, to the sidewalls of the SWNT. These acid-functionalized SWNTs were converted to acid chlorides by derivatization with SOCl(2) and then to amides with terminal diamines such as ethylenediamine, 4,4'-methylenebis(cyclohexylamine), and diethyltoluenediamine. The acid-functionalized SWNTs and the amide derivatives were characterized by a set of materials characterization methods including attenuated total reflectance (ATR) FTIR, Raman and solid state (13)C NMR spectroscopy, transmission electron microscopy (TEM), and thermal gravimetry-mass spectrometry (TG-MS). The degree of SWNT sidewall functionalization with the acid-terminated groups was estimated as 1 in 24 carbons on the basis of TG-MS data. In comparison with the pristine SWNTs, the acid-functionalized SWNTs show an improved solubility in polar solvents, for example, alcohols and water, which enables their processing for incorporation into polymer composite structures as well as for a variety of biomedical applications.

Journal Article↗

PubMed2003

Sidewall functionalization of single-walled carbon nanotubes with organic peroxides.

Single-wall carbon nanotubes (SWNTs) and their fluorinated derivatives (F-SWNTs) were reacted with organic peroxides including benzoyl and lauroyl peroxide to produce phenyl and undecyl sidewall functionalized SWNTs, respectively, which were characterized by Raman, FTIR, and UV-Vis-NIR spectra as well as TGA/MS, TGA/FTIR, and TEM data.

Journal Article↗

PubMed2002

Fluorination of single-wall carbon nanotubes and subsequent derivatization reactions.

This Account focuses on the most recent and systematic efforts in the area of functionalization chemistry of the single-wall carbon nanotubes (SWNTs) which utilizes direct fluorination for the preparation of "fluoronanonotubes" and their subsequent derivatization. The results obtained prove that the addition of fluorine drastically enhances the reactivity of the nanotube side walls. The use of this strategy as a versatile tool for preparation and manipulation of SWNTs with variable side-wall functionalities has been demonstrated. The functionalized SWNTs have shown an improved solubility in selected solvents and significantly altered electrical, mechanical, and optical properties. An overview of new synthetic methods for preparation and a discussion of characterization data for the functionalized SWNTs are provided.

Journal Article↗

PubMedDate not supplied

Oxidative properties and chemical stability of fluoronanotubes in matrixes of binary inorganic compounds.

The chemical stability of fluoronanotubes in selected solid inorganic matrixes has been studied by initially mixing and mechanically grinding the components and subsequently heating them at temperatures ranging from 35 to 600 degrees C. The inorganic compounds selected for matrixes included halides (KBr, KI, Lil, LiBr, LiCl, NaCl, Znl2), oxides (Li2O, Fe2O3, PbO, MnO), lithium peroxide (Li2O2), potassium superoxide (KO2), sulfides (Li2S and ZnS), zinc selenide (ZnSe), lithium nitride (Li3N), and aluminum phosphide (AIP). Solid products, resulting from the proceeding chemical reactions, were analyzed by X-ray diffraction, Raman spectroscopy, and SEM/EDX elemental analysis. Gaseous and volatile products were identified with the help of the TGA/MS technique. Experimental data presented in this paper provide clear evidence that fluoronanotubes are not chemically inert toward the solid matrixes studied and exhibit significant oxidative properties in the redox reactions occurring under various temperatures, depending on the nature of the inorganic compound.

Crystallization↗