Yaroslav Kievsky

Dynamics of molecular diffusion of rhodamine 6G in silica nanochannels

We describe a method to study diffusion of rhodamine 6G dye in single silica nanochannels using arrays of silica nanochannels. Dynamics of the molecules inside single nanochannel is found from the change of the dye concentration in solution with time. A 10(8) decrease in the dye diffusion coefficient relative to water was observed. In comparison to single fluorescent molecule studies, the presented method does not require fluorescence of the diffusing molecules.

Towards Nonspecific Detection of Malignant Cervical Cells with Fluorescent Silica Beads

To date, the methods for detection of cancer cells are mostly based on traditional techniques used in biology, such as visual identification of malignant changes, cell-growth analysis, specific ligand-receptor labeling, or genetic tests. Despite being well developed, these methods are either insufficiently accurate or require a lengthy complicated analysis. A search for alternative methods for the detection of cancer cells may be a fruitful approach. Proposed here is a novel method for the detection of cancer cells in vitro, which is based on nonspecific adhesion of silica beads to cells. First, atomic force microscopy is used to study the adhesion of single silica beads to malignant and normal cells cultured from human cervix. It is found that adhesion depends on the time of contact, and can be statistically different for malignant and normal cells. Using these data, an optical method utilizing fluorescent silica beads is developed, which is based on detection of the difference in the number of adherent particles. The method is tested using primary cells cultured from cervical tissues of three healthy individuals and three patients with cervical cancer. The method shows sufficiently high sensitivity for cancer to make it interesting to perform further statistical tests.

3D design of self-assembled nanoporous colloids

Recently discovered synthesis of unusual curved nanoporous silica shapes, such as rods, discoids, spheres, tubes, and hollow helicoids, have brought forth the problem of understanding the formation mechanism. Knowledge of such mechanism may lead to the ability to control the nanoporous shapes. This is important in a variety of applications and new technologies where nanostructure and geometry determine function. In this work the problem of morphogenesis of nanoporous silica shapes is analyzed. A theoretical basis is outlined to describe the variety of forms and surface designs that result from the liquid crystal stage, silicification and rigidification of shapes. Further experimental evidence in favor of the suggested mechanisms is presented.

Fluorescent silica colloids for study and visualization of skin care products

Background: The efficacy of skin care products depends on the time and dynamics of their absorbance by the skin, and its spatial distribution on the skin. Regular scrape‐based methods may depend on the operator and are destructive and invasive in nature. Here, we describe a novel method based on non‐contact optical measurements to trace the location and dynamics of skin care products on the skin.