Siangproh, WeenaKhamcharoen, WisarutHenry, Charles S.
8页
查看更多>>摘要：This work presents an all-in-one origami paper-based electrochemical platform for simple and inexpensive L- cysteine (Cys) detection using Cys as a monomer for modifying electrode surfaces. The proposed method combines the steps of electropolymerization and detection into a single device to offer a highly convenient method for the end-user. In comparison, the sensitivity toward Cys detection is a significantly increased using this modified electrode. The developed device provided a linear concentration range of 10-800 mu M with a limit of detection of 5.5 mu M. For application, the device was successfully applied to detect Cys in different food products such as wheat flour, bread, and cake with satisfactory results, yielding excellent intra-day and inter-day relative standard deviations (1.5-4.9%) and recoveries (84.2-110.8%). This discovery is important from the viewpoint of the development of Cys detection in other applications in the future.
查看更多>>摘要：Development of noninvasive bioimaging fluorescent probes for detecting particular enzyme activity is greatly recommendable for preclinical diagnosis of cancer. Given that the elevated beta-gal activity is positively correlated with several tumors, developing a fluorescent probe for the sensing of beta-gal is therefore highly desirable for cancer diagnosis. Herein, a new enzyme-activatable near-infrared (NIR) turn-on fluorescent probe (DMC-beta gal) was developed for accurately detecting beta-gal activity characterized by excellent selectivity, high sensitivity (LOD = 0.298 U/L), and low toxicity. More importantly, DMC-beta gal qualifies remarkable NIR excitation (725 nm) and emission wavelength (770 nm), an ideal tool for restrained photodamage and suppressed autofluorescence. The above excellent performance of DMC-beta-gal allowed for the accurate monitoring of endogenous beta-gal in living cells. Moreover, the probe was successfully applied to detect intracellular beta-gal activity in different types of cancer cells, verifying that SKOV-3 cells had a higher level of beta-gal activity than those of A549, HCT-116, MCF-7, and HepG2 cells. Furthermore, DMC-beta gal could real-time visualize endogenously beta-gal in tumor-bearing nude mice with low auto-fluorescence interference. All results fully demonstrated that DMC-beta gal has potential value as a promising strategy for diagnosis of beta-gal-related diseases.
Rios, AngelBartolome, ManuelContento, Ana M.Villasenor, Maria J....
12页
查看更多>>摘要：A current nourishment issue is the development of smart and reliable analytical strategies to control in a simple way main bioactive compounds of nutritional supplements whose increasing use is deemed a trend nowadays. With this aim a quick and highly sensitive plasmonic sensor using simple citrate coated gold nanoparticles (AuNPs) as optical probe, was developed for both qualitative and quantitative global assessment of all the proteinogenic amino acids in nutritional supplements. AuNPs of five different sizes (from 19 to 74 nm) were synthesized, characterized and evaluated as optimal transductor element for the sensing approach. Critical physic-chemical conditions controlling aggregation (pH, incubation time, AuNPs amount and ionic strength) were investigated on the main five types of aas, structurally different attending to their R-side chain and with expected distinctive behaviour on aggregation mechanisms, which are also discussed. All proteinogenic amino acids induced AuNPs aggregation at low pH (2.5) causing a change in the colour solution from red to blue, as well as a redshift in the plasmon band from 518 nm (disperse NPs) to 650 nm (aggregated NPs). Based on this sensing approach two different strategies are allowed, a preliminary qualitative/semi-quantitative screening just by the naked eye (simple spot test) and a second quantitative confirmation procedure using the analytical signal (A650/ A518). Reliability of quantitative approach was assessed by an exhaustive validation procedure, where matrix effects and potential interferences usually present in commercial samples and affecting the analytical signal were mainly focussed. The results for the analysis of complex nutritional samples were validated by means of a statistical comparison with those ones of the official reference Kjeldahl method (paired Student test-t) at a 95% confidence level. This is the first sensing approach able to provide the global estimation of proteinogenic aas amount based on their simply AuNPs aggregation induction, irrespectively of their R-side chain structure.
查看更多>>摘要：Amyloid beta-peptide (A beta) is a key predictor for preclinical diagnosis of Alzheimer's disease (AD) and vascular diseases. In this work, we propose a gold nanoparticle (AuNPs)-A beta-nickel (Ni)-horseradish peroxidase (HRP) based colorimetric assay for the detection of A beta(1-40). The consecutive binding of A beta(1-40) to AuNPs and metal ions is designed and examined for A beta-specific aggregation of AuNPs and the generation of quantitative colorimetric signals. The affinity of A beta(1-40) towards various metal ions was studied first, and two metal ions, Cu and Ni, were specifically tested with Metal Ion-Binding Site Prediction (MIB) and High-resolution Electrospray Ionization Mass Spectrometry (HR-ESI-MS). Subsequently, the binding of A beta(1-40) and AuNPs was examined, and the binding between A beta-AuNPs and Ni-HRP was finally analyzed by UV-Vis and nano-zetasizer. Based on the characterized dual binding of A beta(1-40), a colorimetric sandwich assay was developed and the analytical performance of the developed assay has been evaluated with standard solutions and human serum samples. Good linearity within a range from 0 nM to 10 nM was found. The detection limits of 0.22 nM in the standard sample and 0.23 nM in the human serum sample have been demonstrated. The newly developed colorimetric sandwich assay is a short, simple, antibody-free assay and achieves high sensitivity with only 100 mu L A beta(1-40) samples. The assay has immense potential for the detection of A beta(1-40) in biological or biomedical diagnosis.
查看更多>>摘要：Adulteration of essential oils is a common and serious problem. Adequate and fast methods are required to establish the authenticity and purity. GC-MS, H-1 and C-13 NMR were compared in combination with similarity calculations as well as differential spectroscopy and chromatography for the authentication and determination of purity of vetiver essential oils. In the investigation of eight commercial oils H-1 and C-13 NMR adequately detected all six adulterants encountered in four of the commercial samples, while GC-MS was not able to detect adulteration with vegetable oils. A great advantage of the combined use of similarity calculation and NMR is that the authenticity can be verified without the need of concomitant measurement of a standard sample. The calculation can be carried out with a registered reference spectrum, in the case of 1H NMR acquired using the same magnetic field, but in the case of C-13 NMR the spectrum can be obtained with another magnetic field. H-1 NMR has the advantage of high speed, and the results can be obtained within minutes. C-13 NMR was found to be superior in its ability to provide unequivocal identification of eventual adulterants, with differential spectroscopy revealing all signals of the adulterants.
查看更多>>摘要：Mass Spectrometry Imaging is an effective technology that allows to determine the in-situ distribution of endogen and/or exogen small molecules. It is a rapidly emerging approach for visualizing drugs and their metabolites within biological tissues. Matrix-Assisted Laser Desorption Ionization (MALDI) Mass Spectrometry Imaging (MSI) coupled to high resolving power analyzer (e.g. TOF) was already investigated for metallodrug localization and metabolization studies, but was proved to suffer from a lack of sensitivity and resolution, leading to poor coverage and assignment. To counter these technological limitations, the use of ultra-high resolving power analyzer such as Fourier Transform Ion Cyclotron Resonance (FTICR) could be revealed as a technique of choice. The high field FTICR MS provides ultra-high resolving power and mass accuracy that allows exhaustive molecule coverage and non-ambiguous molecular formula assignments. Platinum derivatives, such as oxaliplatin, are widely used as therapeutic agents for cancer treatment. The assessment of their intake, distribution and metabolism within the organs is important to know the risks associated with their use. In this study, MALDI FTICR MSI analyses were performed to better understand the penetration and metabolization of platinum derivatives in ovaries of women treated by Hyperthermic Intraperitoneal Chemotherapy (HIPEC) for peritoneal metastasis of colorectal or appendicular origin. Twelve ovary sections, from six ovary samples in six women donors, before and after treatment, were analyzed with 120 mu m spatial resolution. For the first time, the high resolving power (220,000 at m/z 457) and sub-ppm accuracy (<1 ppm) of the FTICR combined with an Isotopic Fine Structure study enabled to distinguish two Pt-isobaric species derived from oxaliplatin in biological tissues. One of these, which is unknown, was specifically localized at the contour of the ovary.
查看更多>>摘要：In this paper, a facile hydrothermal combined with subsequent two-step post-calcination method was used to fabricate hematite (alpha-Fe2O3) nanoarrays on fluorine-doped SnO2 glass (FTO). The morphology, crystalline phase, optical property and surface chemical states of the fabricated alpha-Fe2O3 photoelectrode were characterized by scanning electron microscopy, X-ray diffraction, ultraviolet visible spectroscopy and X-ray photoelectron spectroscopy correspondingly. The alpha-Fe2O3 photoelectrode exhibits excellent photoelectrochemical (PEC) response toward hydrogen peroxide (H2O2) in aqueous solutions, with a low detection limit of 20 mu M (S/N = 3) and wide linear range (0.01-0.09, 0.3-4, and 6-16 mM). Additionally, the alpha-Fe2O3 photoelectrode shows satisfying reproducibility, stability, selectivity and good feasibility for real samples. Mechanism analysis indicates, comparing with H2O, H2O2 possesses much more fast reaction kinetics over alpha-Fe2O3 surface, thus the recombination of photogenerated charges are reduced, followed by much more photogenerated electrons are migrated to the counter electrode via external circuit. The insight on the enhanced photocurrent, which is corelative to the concentration of H2O2 in aqueous solution, will stimulate us to further optimize the surface structure of alpha-Fe2O3 to gain highly efficient alpha-Fe2O3 based sensors.
查看更多>>摘要：C Owing to the satisfactory properties such as high specific surface area, finely tunable chemical composition, large yet adjustable pore sizes, and diverse architecture, metal-organic frameworks (MOFs) have the potential to be used as a stable, efficient, reusable and protective biomacromolecule immobilization carrier in capillary electrophoresis. Herein, a novel immobilized receptor open-tubular affinity capillary electrochromatography (OTACEC) strategy was developed for the first time to rapidly investigate the interactions between a set of drugs and bovine serum albumin (BSA). To further increase the amount of immobilized BSA and maintain the bioactivity of BSA, BSA was immobilized on the inner capillary surface by using polydopamine (PDA) as the adhesion layer and surface functionalization agent, a MOF namely dresden university of technology-5 (DUT-5) as supporting platform and biomacromolecule immobilization carrier, respectively. The amount of immobilized BSA on the capillary surface of the BSA@capillary and the PDA/MOFs/BSA@capillary column are separately calculated as 0.00756 nmol and 0.01812 nmol. Besides, the PDA/MOFs/BSA@capillary column was applied to investigate the interactions between BSA and flavonoids, fluoroquinolones. Under the optimal interaction conditions, three flavonoids and three fluoroquinolones are able to achieve baseline separation in the PDA/MOFs/BSA@capillary column (with resolution values of three flavonoids, 5.78 and 4.13; three fluoroquinolones, 1.72 and 1.68). The PDA/MOFs/BSA@capillary column shows good stability and reproducibility over 100 runs (relative standard deviation (RSD)<5%). In addition, the normalized capacity factor (K-RCE) in this method replaced the binding constant and was used as an evaluation index to fast predict the activities of 20 drugs, some of which have not yet been reported for their interactions with BSA. Spectroscopy and molecular docking further illuminated the binding mechanism.
查看更多>>摘要：In this paper, we proposed a dual-signal fluorometric and colorimetric system based on silicon quantum dots (SiQDs) and 4-nitrophenol (4-NP) for pH and urease sensing. SiQDs with fluorescence emission of 460 nm were prepared via aqueous-phase synthesis. As the pH of the system gradually increased, the absorption band of 4-NP at 400 nm increased and a color reaction from colorless to yellow occurred. The absorption of 4-NP overlapped quiet well with the fluorescence excitation spectrum of SiQDs, which can effectively quench the fluorescence of SiQDs. Therefore, the change of fluorescence and absorption intensities could be used to quantify pH value. The fluorometric and colorimetric pH-sensing systems both exhibited a linear respond to pH ranging from 6.0 to 7.8 with an interval of 0.2 pH unit. Urease could specifically hydrolyze urea to generate carbon dioxide and ammonia, causing an obvious increase of the pH value. Thus, urease could also be detected quantitatively by the above dual-signal pH sensing system. The linear ranges of the fluorometric and colorimetric methods for urease detection were both 2-40 U L-1. The limits of detection were 1.67 and 1.07 U L-1, respectively. More importantly, this established dual-signal system has been successfully exploited in the detection of urease in real samples with satisfactory recoveries. Compared with other traditional single-signal assay strategies, the results obtained by dual-signal methods are more accurate and reliable.
NSTL
Elsevier