Search results for "colorimetry"

Toxicity and cell density monitoring in monolayer and three-dimensional cultures with the XTT assay

1998

The application of viability criteria (MTT and XTT tests) to monolayer cultures and immobilised cells in three-dimensional systems was investigated in order to assess cell viability and cell proliferation. The suitability and accuracy of these tests were compared with the conventional criteria (cellular protein and DNA content) used in monolayer cultures for the same purpose. The colorimetric assay based on the metabolic reduction of the tetrazolium salt XTT to a water-soluble formazan proved to be very useful, rapid and sensitive. This automated spectrophotometric enzymatic method, due to its lack of toxicity, also permits repeated nondestructive assays on a single cellular culture for the…

Colorimetric quantitation of trace amounts of sodium lauryl sulfate in the presence of nucleic acids and proteins

1992

A fast and sensitive procedure for the colorimetric detection of sodium lauryl sulfate (SDS) is presented. The assay is based upon the formation of a chloroform-extractable ion pair between lauryl sulfate and methylene blue that is quantified spectrophotometrically with an estimated detection limit of 150 ng of SDS. The method is suitable for the monitoring of contaminating traces of SDS in protein or nucleic acid samples that have the potential to interfere with enzymatic manipulations such as proteolytic digest, restriction analysis, or reverse transcription. Since the procedure is extremely simple and no special equipment is required it is accessible to every researcher concerned with SD…

Comparison of creatinine and inulin clearances in multiple trauma

1990

Creatinine clearance (Ccr) is a good predictor of renal dysfunction. However, numerous analytical interferences have been observed with the classical measurement of creatinine by Jaffé's procedure. This prospective study was conducted to compare 4 methods for determining creatinine; and also endogenous creatinine clearance with inulin clearance (Cin) to estimate the glomerular filtration rate. The 4 different techniques for measuring creatinine were: 1) 2 techniques using Jaffé's colorimetric reaction: one with rapid and the other with slow kinetics: 2) 2 more selective methods: enzymatic procedure and high performance liquid chromatography (HPLC). Measurements were performed in 13 multiple…

Sensitive and selective plasmonic assay for spermine as biomarker in human urine.

2014

A simple, fast, and highly selective and sensitive colorimetric assay to detect nanomolar levels of spermine in human urine (healthy donors, cancer patients) is reported. This assay is based on the absence of a competitive organic capping on the gold nanoparticles together with the high affinity of the amine groups of the analyte for the nanoparticle surface.

A tailor-made nucleoside-based colourimetric probe of formic acid

2014

A ratiometric, specific probe of formic acid has been developed. It is based on intermolecular nucleobase-pairing of inosine-capped plasmonic nanoparticles to form nucleoside channels, which are destabilised by the analyte.

A solid colorimetric sensor for the analysis of amphetamine-like street samples.

2016

A solid sensor obtained by embedding 1,2-naphthoquinone-4-sulfonate (NQS) into polydimethylsiloxane/tetraethylortosilicate/silicon dioxide nanoparticles composite has been developed to identify and determine amphetamine (AMP), methamphetamine (MAMP), 3,4-methylenedioxymetamphetamine (MDMA) and 3,4-methylenedioxyamphetamine (MDA). The analytes are derivatized inside the composite for 10 min to create a colored product which can be then quantified by measuring the diffuse reflectance or the color intensity after processing the digitalized image. Satisfactory limits of detection (0.002–0.005 g mL−1) and relative standard deviations (<10%) have been achieved. The proposed kit has been successfu…

Host Solids Containing Nanoscale Anion-Binding Pockets and Their Use in Selective Sensing Displacement Assays

2005

A specific microassay for evaluating hepatic LDH activity in co-cultures of hepatocytes with other cells.

1994

This study describes the development of a simple, rapid and reproducible microassay for determining the intracellular LDH activity of rat hepatocytes present in a co-culture system with other cells. The procedure involves treatment of cellular homogenates with an anti-LDH antiserum that specifically inhibits the LDH activity of rat hepatocytes. The assay is performed in 96-well plates and LDH activity can be measured directly in the same wells using a colorimetric method. The difference in LDH activity values measured before and after antiserum incubation reflects the LDH content of the hepatocytes in the sample. The advantages of this method are the small number of cells required, a reduct…

A smartphone-based innovative approach to discriminate red pigments in roman frescoes mock-ups

2022

The characterization of red pigments in frescoes wall paintings has been of great interest for researchers to better understand raw material procurement dynamics, pigment receipts, stylistic evolution and to assess their conservation state. In this study a non-destructive colorimetric approach implementing a smartphone-based method was developed in order to be able to distinguish between three pigments made from minium, haematite and cinnabar minerals, and also mixed pigments, preparing frescoes mock-ups following the roman receipt described by Vitruvius. Portable FT-IR, Raman spectroscopy, portable XRF and visible reflectance spectra analyses were carried out as reference methods for smart…

Delivering Inorganic and Organic Reagents and Enzymes from Zein and Developing Optical Sensors.

2018

Nowadays, interest in using environmentally friendly materials is increasing in many fields. However, the rational design of sensors with biodegradable materials is a challenge. The main aim of this work is to show the possibility of using zein, a protein from corn, as a biodegradable and low-cost material for immobilizing, stabilizing, and delivering different kind of reagents for developing optical sensors. Enzymes, metallic salts, and aromatic and small organic compounds were tested. In addition, different techniques of immobilization, entrapment and adsorption, were used, and different formats, such as solid devices and also multiwell platforms, were proposed. The capacity of zein for i…