Search results for "colorimetry"
showing 10 items of 85 documents
Inkjet printing methodologies for drug screening
2010
We show for the first time a contactless, low-cost, and rapid drug screening methodology by employing inkjet printing for molecular dispensing in a microarray format. Picoliter drops containing a model substrate (D-glucose)/ inhibitor (D-glucal) couple were accurately dispensed on a single layer consisting of the enzymatic target (glucose oxidase) covalently linked to a functionalized silicon oxide support. A simple colorimetric detection method allowed one to prove the screening capability of the microarray with the possibility to assay with high reproducibility at the single spot level. Measurements of the optical signal as a function of concentration and of time verified the occurrence a…
Colourimetric image analysis as a diagnostic tool in female genital schistosomiasis
2015
Female genital schistosomiasis (FGS) is a highly prevalent waterborne disease in some of the poorest areas of sub-Saharan Africa. Reliable and affordable diagnostics are unavailable. We explored colourimetric image analysis to identify the characteristic, yellow lesions caused by FGS. We found that the method may yield a sensitivity of 83% and a specificity of 73% in colposcopic images. The accuracy was also explored in images of simulated inferior quality, to assess the possibility of implementing such a method in simple, electronic devices. This represents the first step towards developing a safe and affordable aid in clinical diagnosis, allowing for a point-of-care approach.
Phenolic and Antioxidant Analysis of Olive Leaves Extracts (Olea europaea L.) Obtained by High Voltage Electrical Discharges (HVED)
2019
Background: The aim of this study was to evaluate high voltage electrical discharges (HVED) as a green technology, in order to establish the effectiveness of phenolic extraction from olive leaves against conventional extraction (CE). HVED parameters included different green solvents (water, ethanol), treatment times (3 and 9 min), gases (nitrogen, argon), and voltages (15, 20, 25 kV). Methods: Phenolic compounds were characterized by ultra-performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS), while antioxidant potency (total phenolic content and antioxidant capacity) were monitored spectrophotometrically. Data for Near infrared spectroscopy (NIR) spectroscopy, colorimetry…
Quantitation of HCV-replication using one-step competitive reverse transcription-polymerase chain reaction and a solid phase, colorimetric detection …
1994
A solid phase assay for the colorimetric detection of competitively amplified HCV-cDNA has been established and used to investigate clinical samples from patients with chronic hepatitis. The assay is based on the reduction in the amplification of an hepatitis C virus-related competitor molecule by wild-type hepatitis C virus during polymerase chain reaction. The internal standard contains a lac operator sequence, allowing the amount of amplified competitor to be determined using a lac I-repressor/beta-galactosidase fusion protein. The reduction in the amplification of competitor is dependent upon the concentration of HCV-RNA in the original sample. External hepatitis C virus wild-type stand…
Optical chemosensors and reagents to detect explosives
2012
[EN] This critical review is focused on examples reported from 1947 to 2010 related to the design of chromo-fluorogenic chemosensors and reagents for explosives (141 references). © 2012 The Royal Society of Chemistry.
Selective opening of nanoscopic capped mesoporous inorganic materials with nerve agent simulants; an application to design chromo-fluorogenic probes.
2011
A hybrid nanoscopic capped mesoporous material, that is selectively opened in the presence of nerve agent simulants, has been prepared and used as a probe for the chromo-fluorogenic detection of these chemicals. © 2011 The Royal Society of Chemistry.
Quantitative colorimetric-imaging analysis of nickel in iron meteorites.
2011
A quantitative analytical imaging approach for determining the nickel content of metallic meteorites is proposed. The approach uses a digital image of a series of standard solutions of the nickel-dimethylglyoxime coloured chelate and a meteorite sample solution subjected to the same treatment as the nickel standards for quantitation. The image is processed with suitable software to assign a colour-dependent numerical value (analytical signal) to each standard. Such a value is directly proportional to the analyte concentration, which facilitates construction of a calibration graph where the value for the unknown sample can be interpolated to calculate the nickel content of the meteorite. The…
NQS-Doped PDMS Solid Sensor: From Water Matrix to Urine Enzymatic Application
2021
The development of in situ analytical devices has gained outstanding scientific interest. A solid sensing membrane composed of 1,2-naphthoquinone-4-sulfonate (NQS) derivatizing reagent embedded into a polymeric polydimethylsiloxane (PDMS) composite was proposed for in situ ammonium (NH4+) and urea (NH2CONH2) analysis in water and urine samples, respectively. Satisfactory strategies were also applied for urease-catalyzed hydrolysis of urea, either in solution or glass-supported urease immobilization. Using diffuse reflectance measurements combined with digital image processing of color intensity (RGB coordinates), qualitative and quantitative analyte detection was assessed after the colorime…
Simultaneous application of Fourier transform Raman spectroscopy and differential scanning colorimetry for the in situ investigation of phase transit…
1991
Abstract The combination of Fourier transform Raman spectroscopy with differential scanning colorimetry for the in situ investigation of phase transitions is illustrated using ammonium nitrate as an example. This method helps unambiguous characterisation of different phases by providing a simultaneous probe of thermodynamic and vibrational data.
Hemin-coupled iron(III)-hydroxide nanoparticles show increased uptake in Caco-2 cells
2011
Abstract Objectives The absorption of commonly used ferrous iron salts from intestinal segments at neutral to slightly alkaline pH is low, mainly because soluble ferrous iron is easily oxidized to poorly soluble ferric iron and ferrous iron but not ferric iron is carried by the divalent metal transporter DMT-1. Moreover, ferrous iron frequently causes gastrointestinal side effects. In iron(III)-hydroxide nanoparticles hundreds of ferric iron atoms are safely packed in nanoscaled cores surrounded by a solubilising carbohydrate shell, yet bioavailability from such particles is insufficient when compared with ferrous salts. To increase their intestinal uptake iron(III)-hydroxide nanoparticles …