Bioinspired Rhamnolipids: new bioactive amphiphiles with nanobiotechnological potential

BERTOLINO, MARÍA CANDELARIA; MOTTOLA, MILAGRO; MARTIN, PATRICK; VICO, RAQUEL V.; FANANI, MARÍA L.

Virtual

Congreso; XLIX Reunión Annual SAB; 2021

SOCIEDADA ARGENTINA DE BIOFÍSICA

Surfactants find applications in almost all chemical industries, but their use can have a negative impact on the surrounding and health. Growing environmental concerns have led to the development of innovative and environmentally friendly surfactants. Thanks to their 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 and agriculture . However, natural RLs (produced by Pseudomonas and Burkholderia bacterias) are a difficult mixture to isolate and purify, and they have deleterious effects on eukaryotic cells thus limiting their widespread use. In this work, we study the physicochemical properties of four new bio-inspired mono-rhamnolipids with same acyl length but different sugar-lipid bonds synthesized by our collaborator, Dr. Patrick Martin. We propose that small chemical variations to the natural rhamnolipids can result in new compounds that show enhanced bioactive properties. These molecules were firstly characterized through 1H and 13C NMR, and then their physicochemical and surface activity properties were evaluated in comparison with the natural mixture of RLs produced by Pseudomona aeruginosa. The experimental methodologies used such as Langmuir films and Dynamic Light Scattering allowed us to obtain parameters as the critical micelle concentration (CMC), mean molecular area (MMA), surface tension and their interfacial stability. We found that CMC values were between 0.04 mM to 0.5 mM and MMA values were between 50 to 90 Å2/molecule, being both 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 we observed a decrease in the area occupied by monolayers of RLs spreaded onto a saline solution at pH 7 registered at a constant surface pressure of 20 mN/m as a function of time.