Golden Cancer Diagnosis
Dynamic light scattering (DLS) makes it possible to accurately determine the size and size distribution of various particles – polymers, nanoparticles, proteins. It is especially pleasant that using this method it is possible to determine the presence in the solution of even very low concentrations of various gold nanoparticles (spherical, rods and shells) with sizes from several tens to hundreds of nanometers, due to the strong scattering of light at the wavelengths of surface plasmon resonance.
A group of scientists from the University of Central Florida (USA) suggested that with the help of gold nanoparticles conjugated with antibodies, it is easy, in one stage, to quickly diagnose the presence of markers of certain diseases using DLS. As an example, they showed how one of the markers of prostate cancer can be quickly quantified.
In the blood plasma of a healthy man, prostate-specific antigen (prostate specific antigen, PSA) is present at a concentration of several nanograms per milliliter (it is believed that normally no more than 4 ng / ml), of which unrelated PSA is less than a nanogram per milliliter, that is, about 10% of the total amount of PSA. In the case of cancer or benign prostatic hyperplasia, the total amount of PSA increases, but the relative amount of free PSA in the case of a malignant tumor is lower than in normal or benign degeneration of the prostate gland.
To detect free PSA, scientists used two types of gold nanoparticles associated with different antibodies to this antigen. Spherical gold particles of about 37 nm in size and gold nanopalls of 10-40 nm in length were synthesized. The lower limit of their detection by the DLS method was 0.02 picomol for spherical particles and 0.4 pM for sticks. After binding of nanoparticles with antibodies, their average size increased to 57 nm for spherical particles, and to 30-37 nm for rods. When PSA was added to a solution containing both types of nanoparticles, large oligomeric particles were formed; at the same time, a dependence on the concentration of PSA was observed. The researchers showed that the method allows to determine PSA in concentrations of 0.1-10 ng/ml.
Work "A One-Step Homogeneous Immunoassay for Cancer Biomarker Detection Using Gold Nanoparticle Probes Coupled with Dynamic Light Scattering" published in JACS.
Portal "Eternal youth" www.vechnayamolodost.ru
26.03.2008