Macromolecular recognition at the air-water interface: application of Langmuir-Blodgett technique

The proximate aim of this review is to investigate the specific interaction between two macromolecules, either two complementary strands of DNA or the binding of DNA with a protein. Although a lot of experiments have been done to address these issues, our aim here is different. We either create a dense brush of DNA chains at the air-water interface or orient a large protein, like RNA polymerase, such that they are amenable for specific interaction at the surface. The advantage of our system is that the macromolecules are stretched, oriented parallel to each other, and their concentrations can be made similar to these encountered in real nuclei. In this way we plan to construct an 'artificial nucleus'. Other methods adopted so far can check for the possibility of collective behaviour and the effect of chain elongation or compaction. We have used Langmuir-Blodgett technique for the same and extensively performed FTIR and AFM experiments to monitor the L-B surface. Each macromolecule has been attached by one of its extremities to a hydrophobic buoy to keep it at the interface. Detailed thermodynamic analysis results in some interesting conclusions.