@article { ISI:000314177300008, title = {Influence of the sophorolipid molecular geometry on their self-assembled structures}, journal = {Chemistry-an Asian Journal}, volume = {8}, number = {2}, year = {2013}, month = {FEB}, pages = {369-372}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, keywords = {bolaamphiphiles, helical structures, p-p stacking, Self-assembly, sophorolipids}, issn = {1861-4728}, doi = {10.1002/asia.201200935}, author = {Dhasaiyan, Prabhu and Banerjee, Agnimitra and Visaveliya, Nikunjkumar and Bhagavatula L. V. Prasad} } @article { ISI:000340500300065, title = {Access to harmonine, a chemical weapon of ladybird beetles}, journal = {RSC Advances}, volume = {4}, number = {58}, year = {2014}, month = {JUL}, pages = {30923-30926}, publisher = {ROYAL SOC CHEMISTRY}, type = {Article}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

The synthesis of harmonine, a defense alkaloid from the harlequin ladybird is reported by three different routes. The preparation of several new analogs with the same molecular weight and the decoration of gold nanoparticles with harmonines are also part of the present communication.

}, issn = {2046-2069}, doi = {10.1039/c4ra05859c}, author = {Philkhana, Satish Chandra and Dhasaiyan, Prabhu and Bhagavatula L. V. Prasad and Reddy, D. Srinivasa} } @article { ISI:000335773800005, title = {Vesicle structures from bolaamphiphilic biosurfactants: experimental and molecular dynamics simulation studies on the effect of unsaturation on sophorolipid self-assemblies}, journal = {Chemistry-A European Journal}, volume = {20}, number = {21}, year = {2014}, month = {MAY}, pages = {6246-6250}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

The formation of giant-vesicle-like structures by self-assembling linolenic acid sophorolipid (LNSL) molecules is revealed. Sophorolipids belong to the class of bolaamphiphilic glycolipid biosurfactants. Interestingly, the number of double bonds present in the hydrophobic core of sophorolipids is seen to have a great influence on the type of self-assembled structures formed. Dye encapsulation results establish the presence of an aqueous compartment inside the LNSL vesicles. Molecular dynamics simulation (MD) studies suggest the existence of two possible conformations of LNSLs inside the self-assembled structures and that LNSL molecules arrange in layered structures.

}, keywords = {bolaamphiphiles, MD simulations, Self-assembly, sophorolipids, vesicles}, issn = {0947-6539}, doi = {10.1002/chem.201304719}, author = {Dhasaiyan, Prabhu and Pandey, Prithvi Raj and Visaveliya, Nikunjkumar and Roy, Sudip and Bhagavatula L. V. Prasad} } @article {42665, title = {Self- assembly of isomannide-based monoesters of C18-fatty acids and their cellular uptake studies}, journal = {RSC Advances}, volume = {6}, year = {2016}, month = {JUL}, pages = { 72074-72079}, type = {Article}, abstract = {

The self-assembling behavior of oleic, elaidic and stearic acid-isomannide glycolipids is revealed. Amongst these, oleic and elaidic acid-based isomannide lipids self-assembled to form microspheres which were efficiently taken up by cancer cell lines enabling their usage for drug delivery applications.

}, issn = {2046-2069}, doi = {10.1039/C6RA05608C}, author = {Dhasaiyan, Prabhu and Parekh, Nimisha and Reddy, T. Vijai Kumar and Rani, G. Sandhya and Devi, B. L. A. Prabhavathi and Bhagavatula L. V. Prasad} } @article { ISI:000375723900014, title = {Structural insight into self assembly of sophorolipids: a molecular dynamics simulation study}, journal = {Zeitschrift Fur Physikalische Chemie-International Journal of Research in Physical Chemistry \& Chemical Physics}, volume = {230}, number = {5-7, SI}, year = {2016}, month = {MAY}, pages = {819-836}, publisher = {WALTER DE GRUYTER GMBH}, address = {GENTHINER STRASSE 13, D-10785 BERLIN, GERMANY}, abstract = {

Sophorolipids contain hydrophilic head groups at the ends of a long hydrophobic tail. As a result, sophorolipids can self assemble into variety of structures in water. Atomistic self assembly simulations of sophorolipids are performed in water. Two sophorolipids, oleic acid sophorolipid and linolenic acid sophorolipid, differing in number of double bonds in the hydrophobic tail are considered for this study. Long time self assembly simulations are performed considering 1 :3 lipid to water ratio by weight for both oleic and linolenic acid sophorolipids. In addition to 1 : 3 ratio, long time self assembly simulations are also performed with 1 : 1 and 1 : 2 ratios for linolenic acid sophorolipids. Distinctions in structural arrangements of sophorolipid molecules in the self assembled configuration for all the systems are investigated. The present study aims to provide structural insight into the different self assembled configurations of sophorolipids in water.

}, keywords = {MD Simulation, self assembly, sophorolipids, United Atom Force Field}, issn = {0942-9352}, doi = {10.1515/zpch-2015-0719}, author = {Pandey, Prithvi Raj and Dhasaiyan, Prabhu and Bhagavatula L. V. Prasad and Roy, Sudip} } @article {43356, title = {Micelles versus Ribbons: how congeners drive the self-assembly of acidic sophorolipid biosurfactants}, journal = {ChemPhysChem}, year = {2017}, month = {MAR}, pages = {643-652}, type = {Journal }, abstract = {

Sophorolipids (SLs), a class of microbially derived biosurfactants, are reported by different research groups to have different self-assembled structures (either micelles or giant ribbons) under the same conditions. Here we explore the reasons behind these contradictory results and attribute these differences to the role of specific congeners that are present in minute quantities. We show that a sample composed of a majority of oleic acid (C18:1) sophorolipid in the presence of only 0.5 \% (or more) of congeners with stearic acid (C18:0) or linoleic acid (C18:2) results in the formation of micelles that are stable over long periods of time. Conversely, the presence of only 10 to 15 \% of congeners with a stearic acid chain gives fibrillar structures instead of micelles. To study the mechanisms responsible, oleic acid SLs devoid of any other congeners were prepared. Very interestingly, this sample can self-assemble into either micelles or fibers depending on minute modifications to the self-assembly conditions. The findings are supported by light scattering, small-angle X-ray scattering, transmission electron microscopy under cryogenic conditions, high-pressure liquid chromatography, and NMR spectroscopy.

}, doi = {10.1002/cphc.201601323}, author = {Dhasaiyan, Prabhu and Griel, Patrick Le and Roelants, Sophie and Redant, Emile and Bogaert, Inge N. A. Van and Prevost, Sylvain Francois and Prasad, Bhagavatula L. V. and Baccile, Niki} } @article {42660, title = {Self - assemblies of bolaamphiphilic molecules}, journal = {Chemical Record}, volume = {17}, year = {2017}, month = {NOV}, pages = {1-15}, type = {Article}, chapter = {597-610}, abstract = {

The current buzzword in science and technology is self-assembly and molecular self-assembly is one of the most prominent fields as far as research in chemical and biological sciences is concerned. Generally, self-assembly of molecules occurs through weak non-covalent interactions like hydrogen bonding, π{\textendash}π stacking, hydrophobic effects, etc. Inspired by many natural systems consisting of self-assembled structures, scientists have been trying to understand their formation and mimic such processes in the laboratory to create functional {\textquotedblleft}smart{\textquotedblright} materials, which respond to temperature, light, pH, electromagnetic field, mechanical stress, and/or chemical stimuli. These responses are usually manifested as remarkable changes from the molecular (e. g., conformational state, hierarchical order) to the macroscopic level (e. g., shape, surface properties). Many molecules such as peptides, viruses, and surfactants are known to self-assemble into different structures. Among them, glycolipids are the new entries in the area of molecules that are being investigated for their self-assembly characteristics. Among the different classes of glycolipids like rhamnolipids and trehalose lipids, owing to their biological preparations and their structural novelty, sophorolipids (SLs) are evoking greater interest among researchers. Sophorolipids are a class of asymmetric bolas bearing COOH groups at one end and sophorose (dimeric glucose linked by an unusual β(1{\textrightarrow}2) linkage). The extreme membrane stability of Archaea, attributed to the membrane-spanning bolas (tetraether glycolipids), has inspired chemists to unravel the molecular designs that underpin the self-assembly of bolaamphiphilic molecules. Apart from these self-assembled structures, bolaamphiphiles find applications in many fields such as drug delivery, membrane mimicking, siRNA therapies, etc. The first part of this Personal Account presents some possible self-assembled structures of bolaamphiphiles and their mechanism of formation. The later part covers our work on one of the typical bolaamphiphiles known as sophorolipids.

}, keywords = {Bolaamphiphiles; gels; self-assembly; sophorolipids; vesicles}, issn = {1527-8999}, doi = {10.1002/tcr.201600085}, author = {Dhasaiyan, Prabhu and Bhagavatula L. V. Prasad} } @article {44187, title = {pH- and time-resolved in situ SAXS study of self-assembled twisted ribbons formed by elaidic acid sophorolipids}, journal = {Langmuir}, volume = {34}, year = {2018}, month = {FEB }, pages = {2121-2131}, type = {Article}, abstract = {

Conditions that favor the helical structure formation in structurally similar sophorolipids (SLs), that is, elaidic acid SLs (having a trans double bond between the C9 and C10 positions of the alkyl chain) and stearic acid SLs (no double bond), are presented here. The helical self-assembled structures formed by elaidic acid SLs were independent of pH and also were mediated by a micellar intermediate. On the other hand, the stearic acid SLs formed helical structures under low pH condition only. Astonishingly, the formation routes were found to be different, albeit the molecular geometry of both SLs is similar. Even if a conclusive mechanistic understanding must await further work, our studies strongly point out that the noncovalent weak interactions in elaidic acid SLs are able to overcome the electrostatic repulsions of the sophorolipid carboxylate groups at basic pH and facilitating the formation of helical structures. On the other hand, the hydrophobic interactions in stearic acid SLs endow the helical structures with extra stability, making them less vulnerable to dissolution upon heating.

}, issn = {0743-7463}, doi = {10.1021/acs.langmuir.7b03164}, author = {Dhasaiyan, Prabhu and Prevost, Sylvain and Baccile, Niki and Prasad, Bhagavatula L. V.} } @article {46752, title = {Antibacterial properties of glycosylated surfaces: variation of the glucosidal moiety and fatty acid conformation of grafted microbial glycolipids}, journal = {Molecular Systems Design \& Engineering}, volume = {5}, year = {2020}, month = {AUG}, pages = {1307-1316}, type = {Article}, abstract = {

Glycosylated surfaces can display antimicrobial properties. It has been shown that sophorolipids can be used to develop biocidal coatings against Gram-positive and Gram-negative bacteria, but with a limited efficiency so far. Therefore, it appears necessary to further investigate the surface antibacterial activity of a broader set of structurally related glycolipids. The present work explores the influence of the glucosidic moiety (gluco-, sophoro-, cellobio-) and the fatty acid backbone (saturated,cisortransmonounsaturated). We show that the fatty acid backbone plays an important role:cisderivative of sophorolipids (SL) grafted onto model gold surfaces has better biocidal properties than saturated (SL0) andtransmonounsaturated (SLt) molecules, which appear to be inefficient. The number of glucose units is also a key factor: a one-third decrease in antibacterial activity is observed when having one glucose unit (GL) compared to two (SL). Sugar acetylation (SLa) does not seem to have an impact on the biocidal properties of surfaces. These results are not limited to sophorolipids, with cellobioselipids (CL) leading to similar antibacterial observations.

}, issn = {2058-9689}, doi = {10.1039/d0me00059k}, author = {Valotteau, Claire and Roelants, Sophie L. K. V. and Dhasaiyan, Prabhu and Zibek, Susanne and Guenther, Michael and Soetaert, Wim and Everaert, Bernd and Pradier, Claire-Marie and Babonneau, Florence and Baccile, Niki and Humblot, Vincent} }