Tip Biosystems 509-OD600, Руководство пользователя

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User Manual V1.0.2 35
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Cell Viability - Resazurin/Alamar Blue™
Tip Biosystems offers the measurement of the reduction of resazurin to resofurin. In this cell
viability assay, the resazurin exhibits an absorption peak at 600 nm and the resofurin at 570 nm
wavelengths. An alternate wavelength measurement for absorption peak is available at 630 nm.
Resazurin is an indicator dye which incorporates an oxidation-reduction (REDOX) indicator that
changes color in response to the chemical reduction of growth medium of the growing cells. The
bioassay can be used to establish proliferation or relative cytotoxicity. The toxicity of related
novel agents can be predicted by comparing its baseline data against the baseline data of the
known in-vivo toxicity.
Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles
that are present but undissolved. Determining Turbidity of an aqueous solution is a frequently used
procedure to estimate the quality of water. Turbidity is determined by measuring the optical density
(OD) at 600 nm since light is scattered rather than absorbed. Careful mixing of the suspension is
required before each measurement is taken.
Turbidity - A calibration graph can be plotted using Turbidity 4000 NTU Calibration Standard –
Formazin from Sigma Aldrich (Product number TURB4000). The turbidity of the test solution is
then determined by substituting the OD value in the equation of the straight line that is determined
from the calibration graph.
Turbidity – McFarland for Cell Count
The number of cells in a sample can be estimated by measuring the OD of the cells suspended in
a liquid. A calibration curve from the absorbance of known cell density is plotted and the
absorbance of the unknown cell density is compared against the calibration curve. This is a quick
way to determine the number of bacteria in a sample. The OD value may differ when different
type of cells is used. Therefore, the calibration curve can only be used for the same type of cell.