Mechanistic study of the nucleation and conformational changes of polyamines in presence of phosphate ions

Patrizia Andreozzi; Caterina Ricci; Joaquin Emiliano Martinez Porcel; Paolo Moretti; Desirè Di Silvio; Heinz Amenitsch; Maria Grazia Ortore; Sergio E Moya

doi:10.1016/j.jcis.2019.02.040

Mechanistic study of the nucleation and conformational changes of polyamines in presence of phosphate ions

J Colloid Interface Sci. 2019 May 1:543:335-342. doi: 10.1016/j.jcis.2019.02.040. Epub 2019 Feb 12.

Authors

Patrizia Andreozzi¹, Caterina Ricci², Joaquin Emiliano Martinez Porcel³, Paolo Moretti², Desirè Di Silvio¹, Heinz Amenitsch⁴, Maria Grazia Ortore⁵, Sergio E Moya⁶

Affiliations

¹ Soft Matter Nanotechnology Group, CIC biomaGUNE, Paseo Miramón 182 C, 20014 San Sebastián, Guipúzcoa, Spain.
² Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via brecce bianche, I-60131, Ancona, Italy.
³ Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata, Diag 113 y 64, La Plata, Argentina.
⁴ Institute of Inorganic Chemistry, Graz University of Technology, Stremayergasse 9/V, Graz, Austria.
⁵ Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via brecce bianche, I-60131, Ancona, Italy. Electronic address: m.g.ortore@univpm.it.
⁶ Soft Matter Nanotechnology Group, CIC biomaGUNE, Paseo Miramón 182 C, 20014 San Sebastián, Guipúzcoa, Spain. Electronic address: smoya@cicbiomagune.es.

PMID: 30831359
DOI: 10.1016/j.jcis.2019.02.040

Abstract

Polyamine Phosphate Nanoparticles (PANs) have great potential for the delivery of large therapeutics, such as plasmids and/or siRNAs. The formation of PANs by complexation of Poly(allylamine hydrochloride) (PAH) and phosphate ions from Phosphate Buffer (PB) was studied here, and how it is affected by the presence of phosphate ions from PB and ionic strength. From Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS) the critical PB concentration for PANs formation was determined. Below this critical point, Small Angle X-ray Scattering (SAXS) studies revealed that small PAH-phosphate aggregates coexist with not complexed or weakly complexed polymer chains in solution and that the presence of the phosphate ions increases the Kuhn length of the polymer chains until that only spherical aggregates are present in solution. TEM, DLS and SAXS showed the increase of PANs size with ionic strength up to 250 mM NaCl. At higher NaCl concentrations, PANs disassemble into smaller aggregates. Isothermal Titration Calorimetry (ITC) showed that PAN formation is an exothermic process and the association of phosphates below the critical PB concentration is entropically controlled.

Keywords: DLS; Nanoparticles nucleation; Polyamine phosphate interactions; SAXS; Self-assembled nanoparticles.