An-Hsuan Hsieh1, David S Corti2, Elias I Franses3. 1. Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47907-2100, USA. Electronic address: hsieh25@purdue.edu. 2. Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47907-2100, USA. Electronic address: dscorti@purdue.edu. 3. Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47907-2100, USA. Electronic address: franses@purdue.edu.
Abstract
HYPOTHESIS: Since the volume fraction of the surfactant bilayer(s), of thickness db, in a vesicle and liposome is smaller than one, the dependences of the Rayleigh (R) scattering intensity and turbidity on the particle radius a are weaker than those for a homogeneous sphere, which are proportional to a3. The dependences of the Rayleigh-Debye-Gans (RDG) scattering intensity and turbidity on a are also weaker. Work done: The dependences of the effective relative refractive index on a, db, and dw (water layer thickness) were derived. The specific Rayleigh ratio [Formula: see text] and the specific turbidity τ** for single and independent scattering were derived analytically for R and RDG scattering. Spectroturbidimetry data at 25°C for a cationic double-chain surfactant, didodecyldimethylammonium bromide (DDAB) were compared to the turbidity predictions. FINDINGS: For R scattering, [Formula: see text] and τ** are proportional to a2db for vesicles, and to a3dbdw+db for liposomes. For RDG and particle radii 20-1000 nm, τ** is proportional to an, where n is 2 to 0.4 for vesicles and 2 to 1.1 for liposomes. Turbidity data for DDAB vesicles are consistent with the RDG predictions, which are also used to estimate the vesicles' sizes. RDG applies to liposomes < 800 nm and to much larger sizes for vesicles.
HYPOTHESIS: Since the volume fraction of the surfactant bilayer(s), of thickness db, in a vesicle and liposome is smaller than one, the dependences of the Rayleigh (R) scattering intensity and turbidity on the particle radius a are weaker than those for a homogeneous sphere, which are proportional to a3. The dependences of the Rayleigh-Debye-Gans (RDG) scattering intensity and turbidity on a are also weaker. Work done: The dependences of the effective relative refractive index on a, db, and dw (water layer thickness) were derived. The specific Rayleigh ratio [Formula: see text] and the specific turbidity τ** for single and independent scattering were derived analytically for R and RDG scattering. Spectroturbidimetry data at 25°C for a cationic double-chain surfactant, didodecyldimethylammonium bromide (DDAB) were compared to the turbidity predictions. FINDINGS: For R scattering, [Formula: see text] and τ** are proportional to a2db for vesicles, and to a3dbdw+db for liposomes. For RDG and particle radii 20-1000 nm, τ** is proportional to an, where n is 2 to 0.4 for vesicles and 2 to 1.1 for liposomes. Turbidity data for DDAB vesicles are consistent with the RDG predictions, which are also used to estimate the vesicles' sizes. RDG applies to liposomes < 800 nm and to much larger sizes for vesicles.
Authors: Johann Wachlmayr; Christof Hannesschlaeger; Armin Speletz; Thomas Barta; Anna Eckerstorfer; Christine Siligan; Andreas Horner Journal: Nanoscale Adv Date: 2021-10-18