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1.
Shimada T Ookubo K Komuro N Shimizu T Uehara N 《Langmuir : the ACS journal of surfaces and colloids》2007,23(22):11225-11232
We describe the first determination of thiol compounds with gold nanocomposites composed of gold nanoparticles and thermoresponsive copolymers having polyamino groups. The gold nanocomposites, which are used as a chromatic sensor, reveal chromatic change from blue to red with thermal stimuli, heating followed by cooling the solution. The blue-to-red chromatic change results from disassembly of the gold nanocomposites, which arises from shrinkage of the thermoresponsive copolymers bound to the gold nanoparticle surfaces due to the phase transition induced by thermal stimuli. The disassembly is inhibited by addition of thiol compounds through displacement of the adhered thermoresponsive copolymers. The detached copolymers no longer influence morphological change of the gold nanocomposites. Corresponding with increase of concentration of the thiol compounds, a solution of the gold nanocomposites after the thermal stimuli shows chromatic change, which was quantified with the a* value in L*a*b* chromatic coordinates. A linear relationship between the a* value and concentration of cysteine, examined as a bio-important thiol, is obtained below 7x10(-6) mol dm(-3), estimating a detection limit defined as 3sigma of the blank to be 2.8x10(-7) mol dm(-3). The chromatic sensor of the gold nanocomposites is applied to the determination of cysteine in commercial supplements containing ascorbic acid, which seriously interferes with redox-based determination of cysteine. Analytical results obtained with the chromatic sensor are identical to those obtained with HPLC. 相似文献
2.
The growth of gold nanoparticles without chemical reduction of gold (III) ions was achieved by the disruption of thermoresponsive polymers conjugated with the gold nanoparticles through the phase transition of the polymers. When a solution of gold nanoparticles coated with thermoresponsive polymers was heated, chains of the thermoresponsive polymers were disrupted because of dehydration, resulting in the fusion of gold nanoparticles to form larger nanoparticles. The evolution of the extinction band around 550 nm evidenced the formation of these large (post-fusion) gold nanoparticles, which were characterized by transmission electron microscope (TEM) and dynamic light scattering (DLS). TEM images verified the formation of the large gold nanoparticles having particle sizes of 80-100 nm, whereas DLS indicated the existence of large nanoparticles with hydrodynamic diameters exceeding 200 nm. The deposition did not require the addition of reductants or trivalent gold ions for the formation of the large gold nanoparticles. Both the heating and the solution conditions were studied to elucidate the mechanism of the formation of large gold nanoparticles. 相似文献
3.
Simple and sensitive colorimetric detection of cysteine based on ssDNA-stabilized gold nanoparticles
Zhang Chen Shenglian Luo Chengbin Liu Qingyun Cai 《Analytical and bioanalytical chemistry》2009,395(2):489-494
In this paper, we demonstrate a simple and sensitive colorimetric detection of cysteine based on the cysteine-mediated color
change of ssDNA-stabilized gold nanoparticles (AuNPs). Cysteine is capable of absorbing onto AuNPs surfaces via the strong
interaction between its thiol group and gold. ssDNA molecules which stabilize AuNPs against salt-induced aggregation are removed
away by cysteine encapsulation on the AuNPs surfaces, resulting in a characteristic color change of AuNPs from red to blue
as soon as salt is added. The ratio of absorptions at 640 to 525 nm (A
640/A
525) is linear dependent on the cysteine concentration in the range from 0.1 to 5 μM. Furthermore, amino acids other than cysteine
cannot mediate the color change under the identical conditions due to the absence of thiol groups, suggesting the selectivity
of the proposed method toward cysteine. The employment of complicated protocols and sophisticated processes such as the preparation
of modified AuNPs are successfully avoided in design to realize the simple and low-cost cysteine detection; and the high sensitivity
and low cost of the method is favorable for practical applications.
Figure In the presence of cysteine, cysteine binds to the AuNPs surface via Au-S bond, spontaneously driving ssDNA molecules away
from the nanoparticles, which leads to the AuNPs aggregation under the condition of NaCl introduction, and the corresponding
color change from red to blue. However, the presence of other amino acids results in no color change due to the absence of
thiol groups.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
Xiaofeng Liu Xiaorong He Tonggang Jiu Mingjian Yuan Jialiang Xu Jing Lv Huibiao Liu Yuliang Li 《Chemphyschem》2007,8(6):906-912
A new route is developed to control the self-assembly of gold nanoparticles (AuNPs) functionalized with a novel pyridyl-ended porphyrin-oligo(p-phenylene vinylene) conjugated oligomer (P-OPV-Py) into branched-rods, chain-networks, uniform fractal-like Au clusters, and larger nanoparticles. The techniques of optical spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS) are used to characterize the self-assembly in various solvent systems (pure toluene, CHCl(3)/toluene, THF/toluene and n-butanol/toluene). A combination of the ligand/AuNPs molar ratio and relative concentration serves as the driving force to control the size and shape of P-OPV-Py capped AuNPs. 相似文献
5.
Kim S Kim J Lee NH Jang HH Han MS 《Chemical communications (Cambridge, England)》2011,47(37):10299-10301
Cytidine triphosphate (CTP) stabilized-Au nanoparticles (CTP-AuNPs) allow a quantitative assay of Ca(2+) down to a concentration of 10(-4) M with high selectivity towards Ca(2+) ions over various metal ions including Mg(2+) and the detection range of this probe also can be easily tuned by changing the concentration of CTP. 相似文献
6.
A nonenzymatic electrochemical method is described for the detection of glucose by using gold (Au) nanoparticles self-assembled on a three-dimensional (3D) silicate network obtained by using sol-gel processes. The nanosized Au particles have been self-assembled on the thiol tail groups of the silicate network and enlarged by hydroxylamine. The Au nanoparticles efficiently catalyze the oxidation of glucose at less-positive potential (0.16 V) in phosphate buffer solution (pH 9.2) in the absence of any enzymes or redox mediators. The Au nanoparticle-modified transducer (MPTS-nAuE) was successfully used for the amperometric sensing of glucose and it showed excellent sensitivity with a detection limit of 50 nM. The common interfering agent ascorbate (AA) does not interfere with the detection of glucose. The MPTS-nAuE transducer showed individual voltammetric responses for glucose and AA. This transducer responded linearly to glucose in the range of 0-8 mM and the sensitivity of the transducer was found to be 0.179 nA cm(-2) nM(-1). Excellent reproducibility, and long-term storage and operational stability was observed for this transducer. 相似文献
7.
Zhang Nana Li Jian Zhang Panpan Yang Xiaodi Sun Chong 《Analytical and bioanalytical chemistry》2019,411(27):7105-7113
Analytical and Bioanalytical Chemistry - A novel electrochemical approach for determination of arachidonic acid (ARA) was developed based on the linear arginine-glycine-aspartic-Au (RGD-Au)... 相似文献
8.
Voltammetric determination of cysteine at a graphite electrode modified with gold nanoparticles 总被引:1,自引:0,他引:1
The electrochemical behaviour of cysteine (Cys) at a graphite electrode modified with gold nanoparticles (G-Aunano electrode) was studied by cyclic voltammetry. It was found that the graphite electrode-Au nanoparticles show an electrocatalytic activity towards the oxidation of Cys in 0.1?M NaOH. At 0.05?V, there is an “inverse” maximum in the cathodic voltammogram of Cys. Using a G-Aunano electrode, the dependence of the peak current of the “inverse” maximum on Cys concentration was linear in the range from 1 to 14?pM, and the detection limit was 0.6?pM. The proposed analytical method is simple, rapid and sensitive. 相似文献
9.
We report on the application of an automated and easy-to-use device to directly measure the immunoreactions between adda-specific monoclonal antibodies and microcystins. The antibodies were immobilized on a gold electrode whose surface was modified first with polytyramine and then with gold nanoparticles. The immunoreaction leads to a change in the capacitance of the system. Under optimum conditions, the sensor is capable of performing stable regeneration-assay cycles and has a low detection limit at a concentration of 0.01 pM level of microcystin-leucine-arginine (MC-LR). The surface of the biosensor can be regenerated with pH 2.5 glycine buffer which dissociates the antibody-antigen complex. The biosensor was used to monitor the production of microcystins during batch cultivation of Microcystis aeruginosa (isolated from ponds in Botswana). Liquid chromatography coupled to MS/MS detection was used to identify three variants, viz. MC-LR (995.6 Da), DmMC-LR (981.2 Da) and MC-LA (910.5 Da). Figure
A capacitive immunosensor was fabricated by immobilizing monoclonal antibodies on a polytyramine-gold nanoparticle layer. The immunosensor was used to quantify microcystins produced by Microcystis aeruginosa; MC-LR, DmMC-LR and MC-LA, and further identified by LC- MS/MS. The results show that cumulative determination of microcystin variants is possible with this immunosensor. 相似文献
10.
Chonghui Wang Shigeo Nakamura 《Journal of polymer science. Part A, Polymer chemistry》1995,33(13):2157-2163
Aromatic polyester, copolyester, and poly(ester-amide-thioester) having pendant carboxyl groups are directly synthesized by the organic phase/water phase interfacial polyconden-sation using low-molecular and polymeric phase transfer catalysts. Spectral analysis of the resulting polymers indicates that the nucleophilicity of salts of phenols to diacid chloride is far higher than that of salts of carboxylic acids and chemoselective esterification occurs in a 100% yield. Even if the polymeric catalyst having amino acid moiety as a nucleophilic group is used in the polycondensation, the polymers do not contain anhydride groups. The polyester can be almost quantitatively converted to polymers with different reactive groups by reacting the pendant carboxyl groups with alkyl halides in a DMAc-H2O mixture con-taining K2CO3. A bifunctional catalytic mechanism is proposed for the chemical modification of the polyesters. © 1995 John Wiley & Sons, Inc. 相似文献
11.
Binding of adenosine to the thermosensitive copolymer of N-isopropylacrylamide and 3-(acrylamido)aminophenylboronic acid (82:18, Mn = 47,000 g . mol(-1)) was studied by equilibrium dialysis at 22 degrees C and 37 degrees C, in a 0.1 M glycine buffer containing 0.1 M NaCl at pH 9.2. The copolymer exhibited a the phase transition temperature (T(p)) of 26.5 degrees C under the above conditions. At 22 degrees C the binding of adenosine to the water-soluble copolymer was well described by a Langmuir model, accounting for preferential ionisation of the boronate-nucleoside complexes and, therefore, restricted reactivity of the rest of boronates. At saturation, the copolymer contained 38% of its phenylboronic acid groups in the form of complexes, whereas the association constant was 1,400 M(-1). At 37 degrees C no binding of adenosine to thermally precipitated copolymer was found, presumably owing to interaction of the phenylboronates with hydrophobic segments of polyNIPAM. At high loading of the copolymer by the reversibly bound adenosine the T(p) steeply increases with increasing fraction of the phenylboronate-adenosine complexes in the chains. The increase of the T(p) observed above the saturating adenosine concentration (>1 x 10(-3) M, 22 degrees C) very probably testifies to competition of the nucleoside with hydrophobic polyNIPAM segments for binding to the pendant phenylboronates. 相似文献
12.
Parameters for selective colorimetric sensing of mercury(II) in aqueous solutions using mercaptopropionic acid-modified gold nanoparticles 总被引:1,自引:0,他引:1
We unveil a new homogeneous assay-using mercaptopropionic acid-modified Au nanoparticles in the presence of 2,6-pyridinedicarboxylic acid for the highly selective and sensitive detection of Hg(2+) ions. 相似文献
13.
In this paper, we report a simple, sensitive and selective colorimetric visualization of dopamine (DA) using dithiobis(succinimidylpropionate) (DSP)-modified gold nanoparticles (AuNPs) as probes and ferric ions as cross-linkers. Via the standard amine coupling reaction between the amino groups of DA and activated carboxyl groups of DSP, DA molecules can be assembled onto the surface of DSP-AuNPs. Accordingly, Fe(3+) ions induce a change of DSP-AuNPs in color and UV-vis absorbance by coordinating to the catechol groups of the anchored DA. The pH dependence and mechanism of this method are discussed. A detection limit of 2 nM was obtained, which is lower than those achievable with currently used chromatographic and electrochemical techniques. The feasibility for the detection of DA in artificial cerebrospinal fluid has been demonstrated. 相似文献
14.
15.
Kyung Min Kim Yun-Sik Nam Yeonhee Lee 《International journal of environmental analytical chemistry》2017,97(7):673-683
A sensitive colorimetric method for the determination of iodide ions was developed using gold nanoparticles (AuNPs) functionalised with glycol chitosan (GCS). The iodide ions were at the centre of the O–I––O coordination structure, formed with the GCS-AuNPs, reducing their interparticle distance and inducing aggregation. Time-of-flight secondary ion mass spectrometry analyses showed that the bound iodide ions were coordinated to the oxygen atoms of the ethylene glycol in GCS, with this aggregation leading to a considerable variation in colour from light red to dark violet. Using this GCS-AuNP probe, the iodide ion concentration in environmental, biological and pharmaceutical samples could be determined by both the naked eye and UV-Vis spectroscopy. Additionally, the sensitivity of the detection was found to be markedly enhanced at pH 6, where a more pronounced colour change was observed. The absorption ratio A700/A521 of the functionalised AuNP solution correlated linearly with the iodide ion concentration within the range 0.0–10.0 mg/L, and the limits of detection in tap water, pond water, and bovine serum solution were 3.5, 3.6, and 3.4 μg/L, respectively. The present assay method can thus be utilised to rapidly measure the concentration of iodide ions in aqueous samples. 相似文献
16.
Spain E Miner B Keyes TE Forster RJ 《Chemical communications (Cambridge, England)》2012,48(6):838-840
Suspensions of electrocatalytic gold nanoparticles with radii as small as 83 ± 13 nm that are functionalised with DNA only in one region have been created using templated electrodeposition. The integrity of the bound DNA following nanoparticle desorption from the electrode is demonstrated by detecting picomolar concentrations of DNA without the need for molecular, e.g., PCR or NASBA, amplification. 相似文献
17.
18.
Aggregation of fluorosurfactant-capped gold nanoparticles could be induced selectively by cysteine and homocysteine and, when solution ionic strength was low, the kinetics of homocysteine-induced aggregation of large size nanoparticles (approximately 40 nm) was much faster than that induced by cysteine, leading to specific detection of homocysteine in the presence of excess cysteine. 相似文献
19.
Watanabe S Sonobe M Arai M Tazume Y Matsuo T Nakamura T Yoshida K 《Chemical communications (Cambridge, England)》2002,(23):2866-2867
A gold nanoparticle surface-modified with amide ligands shows enhanced optical sensing of anions: the detection limit is increased by about three orders of magnitude higher than that originally expected from the anion binding ability of neutral amide ligands. 相似文献
20.
A sensor for detecting cysteine (Cys) in a solution of fluorosurfactant (FSN)-capped gold nanoparticles (AuNPs) has been developed. Under acidic conditions, FSN-capped AuNPs are aggregated in the presence of homocysteine (HCys) and Cys but not in the presence of cysteinylglycine, glutathione, and gamma-glutamycysteine. When adding NaOH to a solution of HCys, the five-membered ring transition state is formed through intramolecular hydrogen abstraction. By contrast, it is difficult for Cys to form a four-membered ring transition state after Cys has been pretreated with NaOH. As a result, the HCys-induced aggregation of the FSN-capped AuNPs is suppressed because the five-membered ring transition state exhibits relatively larger steric hindrance and has stronger interaction with the FSN molecules. Thus, we can discriminate between Cys and HCys on the basis of different aggregation kinetics. Under the optimum condition, the selectivity of the probe for Cys in aqueous solutions is remarkably high over the other aminthiols. Note that HCys and Cys have very similar structure and pK(a) value. We have validated the applicability of our method through the analyses of Cys in urine samples. It is believed that this approach has great potential for the detection of Cys in biological samples. 相似文献