Quantification of particle number concentration in liposomal suspensions by Laser Transmission Spectroscopy (LTS)

Simona Sennato; Angelo Sarra; Carlo Panella La Capria; Cecilia Bombelli; Enrica Donati; Paolo Postorino; Federico Bordi

doi:10.1016/j.colsurfb.2023.113137

Quantification of particle number concentration in liposomal suspensions by Laser Transmission Spectroscopy (LTS)

Colloids Surf B Biointerfaces. 2023 Feb:222:113137. doi: 10.1016/j.colsurfb.2023.113137. Epub 2023 Jan 10.

Authors

Simona Sennato¹, Angelo Sarra², Carlo Panella La Capria³, Cecilia Bombelli⁴, Enrica Donati⁵, Paolo Postorino³, Federico Bordi⁶

Affiliations

¹ Institute for Complex Systems, National Research Council (CNR-ISC), Sapienza University of Rome, Piazzale Aldo Moro 2, 00185, Rome, Italy; Physics Department, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185, Rome, Italy. Electronic address: simona.sennato@roma1.infn.it.
² Institute for Complex Systems, National Research Council (CNR-ISC), Sapienza University of Rome, Piazzale Aldo Moro 2, 00185, Rome, Italy; Microscopy Center, University of L'Aquila, Via Vetoio, Coppito, L' Aquila 67100, Italy.
³ Physics Department, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185, Rome, Italy.
⁴ Institute for Biological Systems, National Research Council (ISB-CNR) Secondary Office of Rome-Reaction Mechanisms c/o Department of Chemistry, Sapienza University of Rome, P.le A. Moro 5, 00185 Rome, Italy.
⁵ Institute for Biological Systems, National Research Council (ISB-CNR), Rome1 Research Area, Strada Provinciale 35d 9, Montelibretti, Rome 00010, Italy.
⁶ Institute for Complex Systems, National Research Council (CNR-ISC), Sapienza University of Rome, Piazzale Aldo Moro 2, 00185, Rome, Italy; Physics Department, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185, Rome, Italy.

PMID: 36640540
DOI: 10.1016/j.colsurfb.2023.113137

Abstract

Laser Transmission Spectroscopy (LTS) is an experimental technique able to determine the particle number concentration and the size of colloidal suspensions by a single measurement of the transmittance of a laser beam through the suspension of particles as a function of the wavelength. In this protocol, we show that LTS represents a unique and powerful tool to investigate suspensions of liposomes, where the precise quantification of the number concentration is particularly relevant for the complete definition of the colloidal properties of the suspension. We study a model formulation of Soy-PC:Chol liposomes and we validate LTS results by comparison with High-Performance Liquid Chromatography determination of lipid mass. Then LTS protocols is applied to state-of-art liposomal nanocarrier suspensions. We explain details of data analysis to obtain the particle number concentration by using the Lambert-Beer law and by calculating the extinction cross section, within the framework of Mie theory for spherical vesicles. We also determine the liposome radius and compare it with the hydrodynamic radius measured by Dynamic Light Scattering. As future perspective, we aim to extend LTS analysis to other nanostructures with different geometries and to contribute to the development of new quantitative strategies for the accurate characterization of nanocarriers and other nanoparticles.

Keywords: Counting technique; Extinction coefficient; Laser Transmission Spectroscopy; Liposomes; Particle number concentration.

MeSH terms

Dynamic Light Scattering
Lasers*
Liposomes*
Particle Size
Spectrum Analysis
Suspensions

Substances

Liposomes
Suspensions