title: An improved microfluidics approach for monitoring real-time interaction profiles of ultrafast molecular recognition.
abstract: Our study illustrates the development of a microfluidics (MF) platform combining fluorescence microscopy and femtosecond/picosecond-resolved spectroscopy to investigate ultrafast chemical processes in liquid-phase diffusion-controlled reactions. By controlling the flow rates of two reactants in a specially designed MF chip, sub-100 ns time resolution for the exploration of chemical intermediates of the reaction in the MF channel has been achieved. Our system clearly rules out the possibility of formation of any intermediate reaction product in a so-called fast ionic reaction between sodium hydroxide and phenolphthalein, and reveals a microsecond time scale associated with the formation of the reaction product. We have also used the developed system for the investigation of intermediate states in the molecular recognition of various macromolecular self-assemblies (micelles) and genomic DNA by small organic ligands (Hoechst 33258 and ethidium bromide). We propose our MF-based system to be an alternative to the existing millisecond-resolved "stopped-flow" technique for a broad range of time-resolved (sub-100 ns to minutes) experiments on complex chemical∕biological systems.
authors.affiliation: Unit for Nano Science and Technology, Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098, India.
authors.forename: Subrata
authors.initials: S
authors.lastname: Batabyal
authors.forename: Surajit
authors.initials: S
authors.lastname: Rakshit
authors.forename: Shantimoy
authors.initials: S
authors.lastname: Kar
authors.forename: Samir Kumar
authors.initials: SK
authors.lastname: Pal
mesh_terms: D000818:Animals; D006690:Bisbenzimidazole / Q000737:chemistry; D002621:Chemistry / Q000295:instrumentation*; D004247:DNA / Q000737:chemistry; D004058:Diffusion; D004996:Ethidium / Q000737:chemistry; D008823:Micelles; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D008856:Microscopy, Fluorescence; D013050:Spectrometry, Fluorescence; D013997:Time Factors
chemical_list: D008823:Micelles; D004247:DNA; D004996:Ethidium; D006690:Bisbenzimidazole