Anil Kumar Dasanna, PhD

I am mostly interested in the following areas:

Malaria biophysics
Cell adhesion
Cell mechanics
Active matter and rheology of soft materials.

Here I include some of the most recent problems I've worked on, along with a brief explanation.

How does RBC deformability help parasite alignment?

During the blood stage of infection, merozoites invade healthy RBC to multiply inside them, by evading immune system. Prior to the invasion process, merzoites need to align their apex with RBC membrane surface. This alignment time is measured experimentally and found to be around 10-20 seconds. Here, we asked a question, does RBC deformability help the parasite in the alignment process and does purely passive process such as adhesion explain alignment timescales? We found that RBC deformations help the parasite to align faster. In Fig. (b), the alignment timescales are shown both soft and rigid RBC cases and for two different off-rates which shows that alignment times increases when RBC becomes rigid. More details can be found here and here.

Stability of heterogeneous adhesion bond cluster:

Cell adhesion is the most common mechanism by which cells communicate with extracellular matrix and with other cells. Cells often contain distinct types of receptors/ligands, meant for either single biological function or multiple cellular functions. To understand the role of such heterogeneous environment on the stability of adhesion, we considered simple parallel adhesion cluster where two bond populations with distinct binding kinetics are under the same stretching force as shown in Fig. (a). We showed that the stability of the adhesion cluster is maximised when you have bond populations of comparable binding kinetics. Fig. (b) shows the stability (\chi) in the plane of ratio of spring constants and ratio of on-rates of both populations. More details can be found here.

How does infected RBC interact with endothelium?

The malaria infected RBCs have higher membrane stiffness compared to healthy RBC. These cells are also sticky and both stickiness as well as membrane stiffness increases with post infection time. The adhesion dynamical states in shear flow depend on the post-infection time i.e shape, density of adhesion patches (knobs) and membrane stiffness. Trophozoites, mid-stage infected cells, flip while schizonts, late-stage infected cells, roll on the substarte. The snapshots of cells from both mesoscopic simulations and microfluidic experiments are shown in Fig. (a). More details can be found here. At higher shear rate flows, crawling state (membrane tank-treading) can be observed. This can be seen in a state diagram shown in Fig. (b). More details can be found here.