Amphiphilic surfactants self assemble to form reverse (or inverted) micelles in non-polar solvents in which the polar head groups of the surfactant monomers cluster to form a micellar core directed toward the center of the assembly and the hydrophobic tails extend outward into the bulk organic phase. [1] Reverse micelles are relatively simple yet versatile systems and represent a unique type of self-organized nanostructure (nm size). They provide an attractive model system for biomembranes since they mimic a number of important and essential features of biological membranes although lacking much of the complexity associated with them. The highly structured yet heterogeneous water molecules in reverse micelles represent interesting models for water molecules present in biological systems such as membranes, which are more difficult to analyze experimentally. The key structural parameter of reverse micelles is the [water]/[surfactant] molar ratio (wo), which determines the micellar size as well as the unique physicochemical properties of the entrapped water. The physical and chemical properties of the entrapped water are markedly different from the properties of bulk water but similar in several aspects to those of biological interfacial water as found in membranes or protein interfaces. Reverse micelles therefore represent a type of organized molecular assembly that offer the unique advantage of monitoring dynamics of embedded molecules with varying degrees of hydration. Due to their optical transparency and well defined size (which are advantageous for spectroscopic measurements due to lack of scattering artifacts), reverse micelles represent a suitable model system for studying peptides and proteins in a controlled water-restricted environment. This talk will provide an overview of our group’s work on monitoiring organization and dynamics of probes and peptides bound to AOT reverse micelles of graded hydration using fluorescence-based approaches. [2-6]

Dr Amitabha Chattopadhyay was born on 9th October, 1956 in Calcutta (now Kolkata). He obtained his B.Sc. with Honors in Chemistry from St. Xavier’s College in Calcutta and his M.Sc. from IIT, Kanpur. He received his Ph.D. in 1987 from the State University of New York (SUNY) at Stony Brook, U.S.A. In his Ph.D. research, he developed a convenient and sensitive method, known as the parallax method, to determine membrane penetration depths of a wide variety of membrane-bound fluorophores including proteins and peptides. The parallax method for analysis of membrane penetration depth became very popular in subsequent years. He carried out his postdoctoral work at the University of California, Davis, U.S.A., during 1987-89. In his postdoctoral work, he worked on lipid-protein interactions in the nicotinic acetylcholine receptor from Torpedo californica. He joined the Centre for Cellular and Molecular Biology, Hyderabad, in 1989. He is currently on the editorial boards of several international journals. He has also taught at a number of universities and institutes in India and abroad. Dr. Chattopadhyay has been active in editorial capacity of reputed scientific journals. He has guest edited several issues of journals in areas such as biomembranes and application of fluorescence spectroscopy and microscopy to biological research. These special issues have been very popular.

ACADEMIC & RESEARCH CONTRIBUTIONS: Dr. Chattopadhyay’s work is focused on monitoring organization, dynamics and function in biological membranes in healthy and diseased conditions. His group has made pioneering contribution on the role of membrane lipids in regulating the function of G-protein coupled receptors (GPCR). Subsequently, his group showed that the activity of the serotonin1A receptor is impaired in pathogenic conditions such as the Smith-Lemli-Opitz Syndrome (SLOS). Another seminal contribution from Dr. Chattopadhyay’s laboratory is the role of membrane cholesterol in leishmanial infection.

AWARDS: Dr. Chattopadhyay was elected to the Fellowship of The National Academy of Sciences (1998), Indian Academy of Sciences (1999), Andhra Pradesh Akademi of Sciences (2003) and Indian National Science Academy (2005). He was awarded the Shanti Swarup Bhatnagar Prize (2001), Ranbaxy Research Award (2006), Sreenivasaya Memorial Award (the Society of Biological Chemists) (2000), Raman Research Fellowship (CSIR) (1996), and The Bires Chandra Guha Memorial Lecture award (2008).

1. Luisi, P.L., and Magid, L.J. (1986) CRC Crit. Rev. Biochem. 20: 409-475.
2. Chattopadhyay, A, Mukherjee, S., and Raghuraman, H. (2002) J. Phys. Chem. B 106: 13002-13009.
3. Raghuraman, H., and Chattopadhyay, A. (2003) Langmuir 19: 10332-10341.
4. Kelkar, D.A., and Chattopadhyay, A. (2004) J. Phys. Chem. B 108: 12151-12158
5. Chattopadhyay, A., Arora, A., and Kelkar, D.A. (2005) Eur. Biophys. J. 35: 62-71.
6. Kelkar, D.A., and Chattopadhyay, A. (2005) Biophys. J. 88: 1070-1080

Researchers should cite this work as follows:

• Amitabha Chattopadhyay (2008), "Hydration Dynamics in an Amphiphilic Nanostructure under Controlled Hydration Conditions," https://nanohub.org/resources/4814.

  BibTex | EndNote

1. fluorescence imaging
2. membranes
3. nano/bio
4. Peptides
5. proteins
6. research seminar
7. self-assembly
8. surfactants