Swaminathan Iyer

Detection of surface brush on biological cells in vitro with atomic force microscopy

Observation of a brush on the cell surface with the atomic force microscopy (AFM) in vitro is reported. The number of methods to study brushes that coat living cells is limited despite their biological importance. Moreover, it is important to take into account the brush layer when studying cell mechanics. Here the authors present an AFM method to detect the length and grafting density of the brush on viable cells with resolution that considerably surpasses any existing method. The authors demonstrate this method using cultured human cervical epithelial cells, but it can be applied to any type of cell.

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.

Recovery of Aging-Related Size Increase of Skin Epithelial Cells: In vivo Mouse and In vitro Human Study

The size increase of skin epithelial cells during aging is well-known. Here we demonstrate that treatment of aging cells with cytochalasin B substantially decreases cell size. This decrease was demonstrated on a mouse model and on human skin cells in vitro. Six nude mice were treated by topical application of cytochalasin B on skin of the dorsal left midsection for 140 days (the right side served as control for placebo treatment). An average decrease in cell size of 56±16% resulted. A reduction of cell size was also observed on primary human skin epithelial cells of different in vitro age (passages from 1 to 8). A cell strain obtained from a pool of 6 human subjects was treated with cytochalasin B in vitro for 12 hours. We observed a decrease in cell size that became statistically significant and reached 20–40% for cells of older passage (6–8 passages) whereas no substantial change was observed for younger cells. These results may be important for understanding the aging processes, and for cosmetic treatment of aging skin.

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.

Atomic Force Microscopy Helps to Develop Methods for Physical Detection of Cancerous Cells

Humans are still far from defeating cancer. Early detection of cancer will decrease fatality from this disease. Traditional methods of identification of cancerous cells are mainly based on regular techniques used in biology, such as visual identification of maligant changes, cell growth analysis, specific ligand-receptor labeling, or genetic tests. After many years of research, these methods are still either insufficiently accurate or require a lengthy complicated analysis. It has been recently shown that the atomic force microscopy (AFM) method can be useful in the search for alternative methods for a reliable detection of cancer cells. Here we describe the atomic force microscopy (AFM) study of malignant and normal cells cultured from human cervix. Studying adhesion of AFM probes to both of these types of cells, we found that the adhesion can be statistically different. This finding allows us to propose two novel methods for detection cancer cells by using fluorescent silica beads. The methods show high sensitivity to detect cancer in-vitro. Nevertheless, more statistical data will be needed to determine the actual accuracy of the methods.