Bioinspired Rhamnolipids: new bioactive amphiphiles with nanobiotechnological potential

BERTOLINO, MARIA CANDELARIA; MOTTOLA, MILAGRO; MARTIN, PATRICK; VICO, VIVIANA RAQUEL; FANANI, MARÍA LAURA

Congreso; XLIX Reunión Anual de la Sociedad Argentina de Biofísica; 2021

Sociedad Argentina de Biofísica

Surfactants find applications in almost all chemical industries, but their use can have anegative impact on the surrounding and health. Growing environmental concerns haveled to the development of innovative and environmentally friendly surfactants. Thanks totheir emulsifying, antimicrobial and activating properties of the innate defense of plants,the rhamnolipids (RL) show a high potential for their use in areas such as biomedicine andagriculture[1]. However, natural RLs (produced by Pseudomonas and Burkholderiabacterias) are a difficult mixture to isolate and purify, and they have deleterious effects oneukaryotic cells thus limiting their widespread use.In this work, we study the physicochemical properties of four new bio-inspired monorhamnolipidswith same acyl length but different sugar-lipid bonds synthesized by ourcollaborator, Dr. Patrick Martin. We propose that small chemical variations to the naturalrhamnolipids can result in new compounds that show enhanced bioactive properties.These molecules were firstly characterized through 1H and 13C NMR, and then theirphysicochemical and surface activity properties were evaluated in comparison with thenatural mixture of RLs produced by Pseudomona aeruginosa. The experimentalmethodologies used such as Langmuir films and Dynamic Light Scattering allowed us toobtain parameters as the critical micelle concentration (CMC), mean molecular area(MMA), surface tension and their interfacial stability. We found that CMC values werebetween 0.04 mM to 0.5 mM and MMA values were between 50 to 90 Å2/molecule, beingboth parameters highly dependent on the sugar?s chemical function. On the other hand,all the compounds studied showed a low stability at the air/water interface, since weobserved a decrease in the area occupied by monolayers of RLs spreaded onto a salinesolution at pH 7 registered at a constant surface pressure of 20 mN/m as a function oftime.