Microplate nephelometer for light-scattering and turbidity measurements
The world’s first and only laser-based microplate nephelometer was developed to meet high-throughput demands for fast compound solubility screens. The NEPHELOstar® Plus detects insoluble particles in liquid samples by measuring forward scattered light and can be used for turbidity measurements, drug solubility screening, protein binding kinetics, microbial growth, and petroleum process control.
The NEPHELOstar Plus is a microplate nephelometer with a high-intensity laser diode. It can be up to thirty times more sensitive than traditional transmission optical density readers that measure the reduction in direct light passing through a sample well. Thanks to its speed, flexibility and performance, the NEPHELOstar Plus allows more applications to be adapted to microplate-based laser nephelometry than ever before.
96-well nephelometric assay to detect calcification propensity of serum samplesA Pasch (1) , W Jahnen-Dechent (2), 1) University of Bern , 2) RWTH Aachen University, 07/2013
The precipitation of Ca2+ and phosphate results in calcium phosphate that is used for building up bone and teeth. Disregulation of this strictly regulated process may result in cardiovascular diseases. Here, we present a novel assay to determine the intrinsic ability of serum to inhibit calcification. It relies on the formation of small colloidal protein-mineral complexes, so-called primary calciprotein particles (CPP). These are converted into secondary CPPs and the time it takes for conversion reflects the inhibitory calcification propensity of the serum. Secondary CPPs differ from primary CPPs in regard to particle diameter and shape which can be detected by measuring light scattering.
This nephelometric assay was measured on BMG LABTECH's Nephelostar® Plus in sera of transgenic mice with different propensities to inhibit calcification. These differences were mirrored by differing conversion times of primary to secondary CPPs. Furthermore, different conversion times were determined for hemodialysis patients that have an increased risk in for calcifications.
Nephelometric monitoring growth of Candida albicans using BMG LABTECH's NEPHELOstar PlusU-C. Hipler, Friedrich-Schiller University Jena, 08/2008
Nephelometry measures the forward scattered light when passing solutions. This can be used to determine particles in solution as they increase light-scattering. The particles may be derived from drugs at their limit of solubility or from microbes. Hence, determination of drug-solubility and microbial growth are two main applications for nephelometry.
Using a microplate-based nephelometer, the NEPHELOstar® Plus, solubility of the antifungal substances Econazole-nitrate and ciclopirox-olamine each complexed with Cyclodextrins was monitored and showed a higher solubility than their uncomplexed form. The Cyclodextrin-complexes were studied regarding their antifungal activity on Candida albicans and revealed a higher efficiency of the Econazole complex as compared to the ciclopirox complex.
This study has proven that laser nephelometry in a 96-well microtiter plate can be used as a method for the rapid determination of the solubility of potential drug compounds.
Measuring of rheumatoid factors by the NEPHELOstar Plus microplate readerLisa Mack , Anne Barton, University of Manchester, 08/2005
Rheumatoid Factors (RF) are immunoglobulins which react to antigenic sites on the Fc region of human or animal immunoglobulin G (IgG). Presence of RF is one of the classification criteria for RA and presence of RF is associated with a poorer prognosis such as increased risk of developing erosive disease.
A method of measuring RF uses nephelometry. Patient serum is added to a microplate containing a fixed amount of antigen (IgG). Any RF present will form an antibody-antigen complex with the IgG and the concentration of the RF antibody can be determined by light dispersion. The microplate-based nephelometry reader, the NEPHELOstar® Plus, enables the assay and, hence, provides the advantage of higher throughput, low sample volumes and cost-effectiveness.
Monitoring of microbial growth curves by laser nephelometrySven Brand , Christian Rückert, University of Bielefeld, 07/2004
Nephelometry is a direct method of measuring light scattered by particles suspended in solution at right angles to the beam, or preferably, at a forward angle. In dilute solutions, where absorption and reflection are minimal, the intensity of the scattered light is a function of the concentration of scattering particles such as microbes.
In this application note, the only laser-based microplate nephelometer was used to monitor growth of the Corynebacterium glutamicum. Relative nephelometric units detected by the NEPHELOstar® Plus were compared to OD600 absorbance measurements and revealed that both density measurements correlated well, with nephelometry being the more sensitive method.
A fully automated kinetic solubility screen in 384-well plate format using nephelometryCaroline Green , Seona McKee , Ken Saunders, Pfizer Global Research, 10/2004
The solubility of a potential drug is one of the most important characteristics as water solubility is required to assure activity at site of action. Solubility can be determined by laser nephelometry which detects forward scattered light. If a particle in a solvent (non-solved compound) scatters the light of a laser the signal is increased and reflects the threshold of solubility.
This application note presents the automatic solubility screen for drugs such as Progesterone, Hydrocortizone, Dofetilide and Paracetamol which was achieved by integrating the NEPHELOstar® Plus microplate nephelometer in a liquid handling platform. Test compounds of different concentrations were measured in quadruplicates in 384-well format. A plate of 24 compounds was studied in 75 min and the MARS software automatically calculated the solubility as well as visualized the evaluation as soluble, non-soluble and partially-soluble by a colour-code.