Discipline: Chemistry and Chemical Sciences
Subcategory: Chemical/Bimolecular/Process Engineering
Rasidah O. Ali - Louisiana State University
Co-Author(s): Asela S. Dikkumbura, Louisiana State University, Baton Rouge, LA; and Louis H. Haber, Louisiana State University, Baton Rouge, LA
Time-resolved second harmonic generation (SHG) spectroscopy is used to investigate the influence of acetaminophen (APAP)-induced changes in the adsorption and transport properties of malachite green isothiocyanate (MGITC) dye to the surface of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) liposomes in aqueous colloidal suspension. The adsorption of MGITC to the DOPC liposomes in water is driven by electrostatic and dipole-dipole interactions between the positively charged MGITC molecules and the zwitterionic phospholipid. The SHG intensity increases as the added MGITC dye concentration is increased, reaching a maximum as the MGITC adsorbate at the DOPC liposome bilayer interface approaches a saturation value. The modified Langmuir model is used to fit SHG signals obtained after the addition of dye as a function of concentration to obtain the adsorption free energies, adsorbate site densities and adsorption equilibrium constants for MGITC to the DOPC liposome with and without APAP. The molecular transport of MGITC through the liposome bilayer is found to be more rapid in pure DOPC liposome surface than with APAP additions, especially at higher MGITC concentrations. The addition of APAP is shown to increase MGITC adsorption to the liposome interface, resulting in a larger adsorption equilibrium constant and a higher adsorption site density. In a related study, SHG measurements are performed to investigate molecular adsorption and transport kinetics of malachite green (MG) at the surface of gram-negative, antibiotic resistant bacteria Pseudomonas aeruginosa. This work demonstrates a pathway for investigating potential drug-delivery processes in bacteria and for understanding the mechanism of drug incorporation in altered chemical and physical environments.
Funder Acknowledgement(s): National Science Foundation Bridge to DoctorateNational Science Foundation GRFP
Faculty Advisor: Louis Haber, email@example.com
Role: I contributed 50/50 working alongside senior student Asela handling conducting the SHG experiments, analyzing data such as SHG spectrographs, SHG Time profiles, SHG adsorption isotherms. Alongside working with Asela and Dr. Haber on the manuscript edits for publication.