Single-walled Carbon Nanotubes For Detection Research Articles

A novel sensor made of Antimony Doped Tin Oxide-silica composite sol on a glassy carbon electrode modified by single-walled carbon nanotubes for detection of norepinephrine

In this study, we designed a novel molecularly imprinted polymer (MIP), Antimony Doped Tin Oxide (ATO)-silica composite sol, which was made using a sol–gel method. Then a sensitive and selective imprinted electrochemical sensor was constructed with the ATO-silica composite sol on a glassy carbon electrode modified by single-walled carbon nanotubes (SWNTs). The introduction of SWNTs increased the sensitivity of the MIP sensor. The surface morphology of the MIP and MIP/SWNTs were characterized by scanning electron microscopy (SEM), and the optimal conditions for detection were determined. The oxidative peak current increased linearly with the concentration of norepinephrine in the range of 9.99×10−8M to 1.50×10−5M, as detected by cyclic voltammetry (CV), the detection limit was 3.33×10−8M (S/N=3). In addition, the proposed electrochemical sensors were successfully applied to detect the norepinephrine concentration in human blood serum samples. The recoveries of the sensors varied from 99.67% to 104.17%, indicating that the sensor has potential for the determination of norepinephrine in clinical tests. Moreover, the imprinted electrochemical sensor was used to selectively detect norepinephrine. The analytical application was conducted successfully and yielded accurate and precise results.

A visible and colorimetric aptasensor based on DNA-capped single-walled carbon nanotubes for detection of exosomes

Recently, many studies have shown the potential use of circulating exosomes as novel biomarkers for monitoring and predicting a number of complex diseases, including cancer. However, reliable and cost-effective detection of exosomes in routine clinical settings, still remain a difficult task, mainly due to the lack of adequately easy and fast assay platforms. Therefore, we demonstrate here the development of a visible and simple method for the detection of exosomes by integrating single-walled carbon nanotubes that being excellent water solubility (s-SWCNTs) and aptamer. Aptamers, specific to exosomes transmembrane protein CD63, are absorbed onto the surface of s-SWCNTs and improve the minic peroxidase activity of s-SWCNTs, which can efficiently catalyze H2O2-mediated oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) and lead to a change from colorless to blue in solution. However, after adding exosomes, the aptamers are bound with CD63, leaving from the surface of s-SWCNTs through conformational changes, which results the color of solution from deep to moderate, and this can be observed by the naked eye and monitored by UV–vis spectrometry. Under optimal conditions, the linear range of exosomes is estimated to be 1.84×106 to 2.21×107 particles/μL with a detection of limit (LOD) of 5.2×105 particles/μL. Consequently, a visible and simple approach detecting exosomes is successfully constructed. Moreover, this proposed colorimetric aptasensor can be universally applicable for the detection of other targets by simple change the aptamer.

Chemiresistive sensor based on polythiophene-modified single-walled carbon nanotubes for detection ofNO2

In the present investigation, a chemiresistive sensor based on conducting polythiophene-modified single-walled carbon nanotubes (SWNTs) for NO2detection has been reported. The SWNTs were aligned across 3 μm gap between two gold microelectrodes on Si / SiO2substrate. Alignment of SWNTs was carried out by using AC dielectrophoretic technique and it was confirmed by current–voltage (I–V) measurement. Aligned SWNTs were modified by conducting polythiophene using charge controlled potentiostatic deposition and it was confirmed by field-effect transistor (FET) and electrochemical measurements. Polythiophene-modified SWNT devices were used for the NO2detection in chemiresistive modality. This sensor exhibited very good linear response range from 10 ppb to 10 ppm.

Hexafluorobisphenol A Covalently Functionalized Single-Walled Carbon Nanotubes for Detection of Dimethyl Methylphosphonate Vapor

Hexafluorobisphenol A (6FBPA), as a novel nerve agents sensing molecule, has been successfully attached onto the surface of single-walled carbon nanotubes (SWNTs). The sensing groups have been confirmed by infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectrometry. The results revealed that the sensing groups had been successfully anchored on the surface of nanotubes. The quantitative determination of the functional groups has also been carried out through characterization by thermogravimetric analysis. Furthermore, the morphology of the resultant SWNT-6FBPA hybrids has been observed by transmission electron microscopy and scanning electron microscopy. Due to the existence of phenolic hydroxyl groups, which can form strong hydrogen-bonding with dimethyl methylphosphonate (DMMP) (simulant of nerve agent sarin), the functionalized SWNTs showed excellent sensitivity and selectivity while the sensing devices have been fabricated.

Combing DNAzyme with single-walled carbon nanotubes for detection of Pb(ii) in water

A sensitive and simple assay for the detection of Pb(2+) in aqueous solutions is reported. It takes advantage of the high affinity between single-stranded DNA (ssDNA) and single-walled carbon nanotubes (SWCNT) as well as the capability of SWCNT in fluorescence quenching. Lead(II) catalyzes the cleavage of a fluorescently labeled DNA substrate by a DNAzyme, which releases the single-stranded product to be adsorbed onto a SWCNT. The decrease in fluorescence is proportional to the Pb(2+) concentration. Concentrations as low as 1 nM Pb(2+) in water could be detected and the detection range spans over 5 orders of magnitude. The unique combination of Pb-specific DNAzyme with SWCNT produces a universal, facile and cost-effective sensing platform for lead ions. The concept can be applied to the design of detection assays for other metal ions or small molecules.

Abstract 3686: Antibody-functionalized single-walled carbon nanotubes for detection and selective destruction of breast and pancreas cancer cells

Abstract Nanocarrier-based antibody targeting is a promising modality in therapeutic and diagnostic oncology. Single-walled carbon nanotubes (SWNTs) exhibit two unique optical properties that can be exploited for such applications, i.e., strong Raman signal for cancer cell detection and near-infrared (NIR) absorbance for selective photothermal ablation of tumors. In the present study, we constructed a HER2 IgY-SWNT complex and a MUC4 IgG-SWNT complex, and demonstrated in vitro their dual functionality for both detection and selective destruction of breast and pancreas cancer cells. The two complexes were constructed by covalently conjugating carboxylated SWNTs with anti-HER2 chicken polyclonal IgY antibody and with anti-MUC4 mouse monoclonal IgG antibody, respectively. Raman signals were recorded on a Raman spectrometer with a laser excitation at 785 nm. NIR irradiation was performed using a diode laser system, and cells with or without nanotube treatment were irradiated by 808 nm laser at 50 W/cm2 for 5 min. Cell viability was examined by calcein AM/ethidium homodimer-1 (EthD-1) staining. Immunohistochemical studies showed that HER2 IgY-SWNT complex specifically targeted receptor-expressing SK-BR-3 cells but not receptor-negative MCF-7 cells; MUC4 IgG-SWNT complex specifically targeted pancreatic cancer cells but not normal pancreas cells. Using a Raman optical microscope, we found the Raman signal collected at single-cell level from the complex-treated breast or pancreatic cancer cells was significantly greater than that from various control cells. NIR irradiation selectively destroyed the complex-targeted breast and pancreatic cancer cells without harming receptor-free cells. The death rate after NIR irradiation were 94.1% and 96.6% respectively for complex-treated breast and pancreatic cancer cells, but only 1.3% and 1.8% for the untreated controls of the two cancer cell types, respectively. These results demonstrated that the antibody-SWNT complexes have the potential to detect cancer cells at the early stages of tumor development. In addition, the complexes are potentially useful for selectively killing cancer cells while sparing healthy ones. Thus, the unique intrinsic properties of SWNTs combined with high specificity and sensitivity of antibodies can lead to new strategies for cancer detection and therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3686.

Novel pyrenehexafluoroisopropanol derivative-decorated single-walled carbon nanotubes for detection of nerve agents by strong hydrogen-bonding interaction

Fabrication of hybridized single-walled carbon nanotube (SWNT) device based on novel sensing material N-4-Hexafluoroisopropanolphenyl-1-pyrenebutyramide (HFIPP) via facile approach has been reported for the first time. Considered that strong hydrogen-bonding can be formed between HFIPP and dimethyl methylphosphonate (DMMP) (simulant of nerve agent sarin), the HFIPP-decorated SWNT device has been employed to detect DMMP. The detection limit achieved with our sensor is as low as 50 ppb; moreover, the response and reproducibility can be presented clearly even at very low concentration of DMMP. Excellent sensitivity and selectivity of the hybridized SWNT-HFIPP device suggest that it has great potential application for detecting explosives and nerve agents. In order to investigate sensing mechanism of SWNT-HFIPP for DMMP, control electrical and fluorescent experiments have been carried out and discussed in the present paper.

P-Hexafluoroisopropanol phenyl covalently functionalized single-walled carbon nanotubes for detection of nerve agents

Novel p-hexafluoroisopropanol phenyl (HFIPPH) covalently functionalized single-walled carbon nanotubes (SWCNTs) have been prepared through in situ diazonium reaction between SWCNTs and p-hexafluoroisopropanol aniline; moreover, the hybridized material can be characterized by ultraviolet vision near infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, X-ray photoelectron spectrometry, field-emission scanning electron microscopy and high resolution transmission electron microscopy. The results reveal that the one-dimensional electronic structures of the functionalized tubes could be basically maintained without damaging their electronic properties. Considered that strong hydrogen-bonding can be formed between hexafluoroisopropanol groups and dimethyl methylphosphonate (DMMP) (simulant of nerve agent sarin), the SWCNT-HFIPPH sensing devices have been fabricated and employed to detect DMMP. Excellent sensitivity and selectivity of the hybridized SWCNT-HFIPPH devices suggest that it has great capability of detecting explosives and chemical warfare agents.

Anti-HER2 IgY antibody-functionalized single-walled carbon nanotubes for detection and selective destruction of breast cancer cells

BackgroundNanocarrier-based antibody targeting is a promising modality in therapeutic and diagnostic oncology. Single-walled carbon nanotubes (SWNTs) exhibit two unique optical properties that can be exploited for these applications, strong Raman signal for cancer cell detection and near-infrared (NIR) absorbance for selective photothermal ablation of tumors. In the present study, we constructed a HER2 IgY-SWNT complex and demonstrated its dual functionality for both detection and selective destruction of cancer cells in an in vitro model consisting of HER2-expressing SK-BR-3 cells and HER2-negative MCF-7 cells.MethodsThe complex was constructed by covalently conjugating carboxylated SWNTs with anti-HER2 chicken IgY antibody, which is more specific and sensitive than mammalian IgGs. Raman signals were recorded on Raman spectrometers with a laser excitation at 785 nm. NIR irradiation was performed using a diode laser system, and cells with or without nanotube treatment were irradiated by 808 nm laser at 5 W/cm2 for 2 min. Cell viability was examined by the calcein AM/ethidium homodimer-1 (EthD-1) staining.ResultsUsing a Raman optical microscope, we found the Raman signal collected at single-cell level from the complex-treated SK-BR-3 cells was significantly greater than that from various control cells. NIR irradiation selectively destroyed the complex-targeted breast cancer cells without harming receptor-free cells. The cell death was effectuated without the need of internalization of SWNTs by the cancer cells, a finding that has not been reported previously.ConclusionWe have demonstrated that the HER2 IgY-SWNT complex specifically targeted HER2-expressing SK-BR-3 cells but not receptor-negative MCF-7 cells. The complex can be potentially used for both detection and selective photothermal ablation of receptor-positive breast cancer cells without the need of internalization by the cells. Thus, the unique intrinsic properties of SWNTs combined with high specificity and sensitivity of IgY antibodies can lead to new strategies for cancer detection and therapy.

Decoration of Gold Nanoparticles on Surface-Grown Single-Walled Carbon Nanotubes for Detection of Every Nanotube by Surface-Enhanced Raman Spectroscopy

An electroless deposition method comprised of seed formation and subsequent seeded growth is developed for the decoration of surface-grown single-walled carbon nanotubes (SWCNTs) with gold nanoparticles of controlled size and interparticle distance. The density of the gold nanoparticles is determined by the density of seeds. Gold seeds are used for the SWCNT arrays grown on SiO(x)/Si substrates. For the dense SWCNT arrays on quartz, palladium seeds are used because it is much easier to obtain higher quantities of seeds. Attributed to both the seed formation specified on SWCNTs and the succedent efficient seeded growth process, the gold nanoparticles deposit on SWCNTs with very high selectivity. This electroless method shows no selectivity on types, defects, and conductivity of the SWCNTs, and thus ensures the uniform decoration of all SWCNTs on the wafer. Most importantly, this method provides the possibility to realize the optimal configurations of gold nanoparticles on SWCNTs for obtaining maximal surface-enhanced effects and consequently surface-enhanced Raman spectrum (SERS) of each SWCNT. Thus, both the in situ Raman detection of every SWCNT including those nonresonant with laser energy and the observation of the radial breathing modes of SWCNTs originally undetectable with resonance Raman spectroscopy are achieved. Further investigations over the effect of the laser wavelength and the interparticle distance on the SERS enhancement factors of SWCNTs prove that the coupled surface plasmon resonance absorption of the high-density gold nanoparticles decorated on SWCNTs contributes most to the strong surface enhancement.

Overflow of catecholamine neurotransmitters to the circulation: source, fate, and functions

Article de synthese sur l'efflux des neurotransmetteurs catecholaminergiques chez les mammiferes. Origine des catecholamines: la noradrenaline, l'adrenaline et la dopamine dans le plasma et l'urine. Decharge de ces catecholamines dans le corps entier et dans les differents organes. Etude des determinants de la decharge de la noradrenaline des nerfs sympathiques vers la circulation. Utilisation des mesures du taux de decharge dans l'estimation du mode de decharge des nerfs