My research interests are in developing simple models of complex biological processes and study them by using tools of statistical physics like generating functions, exact transfer matrix, Monte Carlo and molecular dynamics simulations.
The melting or unzipping of DNA is a crucial step in many biological processes such as DNA replication and RNA transcription. In these processes, the strands of the dsDNA, which is a bound state of two polymers or strands held together by hydrogen bonds of base pair, are separated by mechanical force exerted by enzymes like helicases and polymerases. It is now possible to apply and measure forces in the piconewton range by using single molecule manipulation techniques, like atomic force microscopy, optical and magnetic tweezers, and study the structure and function of biomolecules. The theoretical studies on simpler models, like free jointed chain and worm like chain, help to understand the experimental results better and provide new insights to the problem.
We have modelled the strands of the DNA by directed self avoiding walks on the square lattice in the presence of an external force, and obtained many interesting results including phase diagrams, changing of the order of the transition due to the presence of single stranded binding proteins, and the existence of a critical end point in the presence of an attractive surface near DNA.
Presently, I am exploring the surface-polymer interaction via external forcing of the polymer and the behavior of particles or fluids on a fluctuating membrane.
- Rajeev Kapri , J. Chem. Phys., 130 , 145105 (2009), Can a double stranded DNA be unzipped by pulling a single strand ?: Phases of adsorbed DNA .
- Rajeev Kapri and S. M. Bhattacharjee, Europhysics Lett., 83 , 68002 (2008), Manipulating a single adsorbed DNA for a critical end point .
- Rajeev Kapri and S. M. Bhattacharjee, Phys. Rev. Lett., 98 , 098101 (2007), Randomly forced DNA .
- Rajeev Kapri , S. M. Bhattacharjee, Phys. Rev. E, 72 , 051803 (2005), Unzipping an adsorbed polymer in a dirty or random environment .
- Rajeev Kapri , S. M. Bhattacharjee and F. Seno, Phys. Rev. Lett., 93 , 248102 (2004), Complete phase diagram of DNA unzipping : Eye, Y-Fork and Triple point .