Design and Simulation of an Integrated Centrifugal Microfluidic Device for CTCs Separation and Cell Lysis
Separation of circulating tumor cells (CTCs) from a blood sample and subsequent extraction of DNA from these cells play an important role in cancer research and drug discovery. Microfluidics is a versatile technology that has been applied to creating niche solutions for biomedical applications, such as cell separation and mixing, droplet generation, bioprinting, and organs on a chip. Centrifugal microfluidic biochips made on a compact disc showing great potential in processing biological samples for point of care diagnostics.
This study investigates the design and numerical simulation of integrated microfluidic devices, including cell separation unit to isolate CTCs from blood samples and micromixer unit for cell lysis on a rotating disk platform. For this purpose, the inertial microfluidic device designed for the separation of target cells using microchannel arrays contraction-expansion. In addition, the micromixer established to separate the target cells with a mixture of chemical reactants that dissolve the cell membrane lysis them to facilitate further tests. Our numerical simulations validated approach to both cell division and unit micromixer and strengthen the existing experimental results.
In the first compartment of the proposed device (cell separation unit), several simulations were carried out at a different angular velocity of 500 rpm to 3000 rpm to find the optimal angle speed for maximum separation efficiency. By using inertial separation of the proposed approach, CTCs, successfully separated from white blood cells (leukocytes) with a high efficiency (~ 90%) in the angular speed of 2000 rpm. In addition, the meandering channel with square obstacles designed to achieve highly efficient micromixer units with high quality mixing (~ 98%) to isolate CTCs lysis at 2000 rpm.
BIOCHEMICAL PROPERTIES OF THE NETWORK OF carboxypeptidase a UNTRANSFERRED AND FROM malignant neoplasms of the mammary gland
To study the biochemical properties of carboxypeptidase A from untransformed tissue and malignant neoplasms glands of mammals. Sampling anatomical materials for research conducted with adherence to ethical and legal standards.
Excretion of these enzymes include gradual fractionation with (NH4) 2SO4, dialysis in the presence of 2.0 мМ Zn ++ and gel chromatography on sephadex – G 75. Investigations substrate specificity of the enzyme substrate is held by hydrolysis carbobenzoxyphenylalanine, phenylalanylalanine, glutamyltyrosine, prolylalanine (2, 0 mM), hemoglobin and casein (2.0%). Effect of inhibitors and activators is determined in the presence of: Zn ++, cysteine, triton X-100, soybean trypsin inhibitor, leupeptin, pepstatin, PHMB, PMSF, dimethylmolyemydanhydride, tozylheptanol, mercaptoethanol, EDTA and 1.10 – fenantrolin.
Maximum velocity (Vmax), Mihaelis constant (Km), the type of inhibition and inhibition constant (Ki) were analyzed by Lineweaver – Burk method. Carboxypeptidase A from untransformed tissue and malignant neoplasms mammalian gland better divide the substrate, which has both hydrophobic and aromatic amino acids. A carboxypeptidase activity of mammalian gland malignant tumors was inhibited most of all under the influence of soybean trypsin inhibitor and PMSF, in contrast to untransformed tissue.Connection error.
To Carboxypeptidase A from untransformed tissue of the mammalian gland Km = 0.24 mM, and Ki = 0.40 mM determined, to carboxypeptidase A of a mammalian gland malignant neoplasms – Km = 0.17 mM, and Ki = 0, 65 mM. Carboxypeptidase A from untransformed tissue and mammalian gland malignant neoplasm identical to the specificity of the substrate