Tumor Cell Behavior in Porous Hydrogels: Effect of Application Technique and Doxorubicin Treatment.

The effect of porosity on diffusion characteristics of scaffolds and invasive capacity of MCF-7 and PC-3 tumor cells was studied for gelatin hydrogels. According to MTS test results, the efficiency of population of a macroporous cryogel by cells applied by different techniques increased in the following order: migration from the monolayer

Conjugation of succinic acid to non-ionogenic amphiphilic polymers modulates their interaction with cell plasma membrane and reduces cytotoxic activity.

Pluronic block copolymers L61 and L121 were reacted with succinic anhydride to produce, respectively, their mono- and bisderivatives with succinic acid. The critical micelle concentration of Pluronics decreased after modification. The modification of Pluronic L61 promoted its association with the plasma membrane of human cells and increased membrane damage, while the membranotropic activity of modified Pluronic L121 reduced compared to the initial copolymer. Modified Pluronics interfered with the viability, apoptosis induction and metabolism of A549 cells and skin fibroblasts to a much lesser extent presumably due to the introduction of succinic acid residue inhibited intracellular penetration of copolymers. Modified Pluronic L121 promoted the cellular uptake of doxorubicin and rhodamine 123 in A549 cells attributed to the inhibition of membrane P-glycoprotein. Our study provides an approach to assessing the mechanism of interaction of amphiphilic polymers with living cells and demonstrates that Pluronic-succinic acid conjugates can be used as safe and efficient modulators of intracellular drug delivery.

Monitoring of the Zeta Potential of Human Cells upon Reduction in Their Viability and Interaction with Polymers.

The dynamic light scattering (DLS) technique was applied in order to assess the zeta potential of the plasma membrane of human cells. At pH 7.4, the cell zeta potential for different types of cells showed variations over a wide range and was equal to -19.4 ± 0.8 mV for HeLa cells and -31.8 ± 1.1 mV for erythrocytes. The difference could presumably be attributed to the differences in the biochemical composition of the cell plasma membrane. As a result of the heating of HeLa cells, the zeta potential shifted towards more negative voltages by 4.2 mV. An increase in the zeta potential correlated with an increase in the content of phosphatidylserine on the cell surface, which is considered to be an early marker of apoptosis. The DLS technique was also used to study the interactions between the cells and membranotropic polymers, such as polycations and nonionogenic Pluronic L121.

[Carbon nanotube-based biosensors for DNA structure characterization].

The possibility of DNA detection using electrodes modified with carbon nanotubes (CNTs) was studied. CNTs facilitate the electrochemical oxidation of DNA guanine nucleotide, which allows direct detection of DNA on a modified electrode. Electrochemical properties of DNA depend on its secondary structure and molecular weight. Denaturation of native DNA improves the adsorption of biopolymer on CNTs and results in an increase in DNA oxidation current on the modified electrode. A similar effect is observed after ultrasonic shearing of DNA or its treatment with Fenton's reagent due to the fragmentation of biopolymer. Our results demonstrate the feasibility of biosensors based on CNT-modified electrodes for the direct detection and characterization of DNA and DNA damaging factors.