Supercritical CO₂dried chitosan nanoparticles: production and characterization

Abstract

Herein are reported the production and characteristics of chitosan nanoparticles that go through supercritical CO 2 drying. First, chitosan nanoparticles in aqueous colloidal suspension were produced by ionic crosslinking with sodium tripolyphosphate. The produced nanoparticles have a surface charge (z-potential) of +27 mV and an average diameter of approximately 100 nm, measured by dynamic light scattering and field emissionscanning electron microscopy observations. The liquid phase of the nanoparticle suspension was replaced successively with ethanol and supercritical CO 2 to produce dried chitosan nanoparticles finally. The main characteristics of the obtained nanoparticles were determined by diverse analytical techniques. Infrared spectroscopy, solid-state 13 C nuclear magnetic resonance and X-ray diffraction studies were performed to explore possible physicochemical changes induced by the drying procedure. Also, the thermal stability of the dry chitosan nanoparticles was determined by thermogravimetric assay and dynamic scanning calorimetry.Structural properties were analyzed and compared with lyophilized nanoparticles finding that the supercritically dried chitosan nanoparticles have a surface area an order of magnitude higher. Microscopy images showed that the supercritically dried chitosan nanoparticles have a porous conglomerated structure, suggesting that there is particle aggregation through the drying process. Notwithstanding, the dry chitosan nanoparticles resuspended in the dilute acid medium readily; microscopy observations showed that the size of the resuspended particles remains in the nanoscale range. The proposed procedure is able to furnish dried chitosan nanoparticles with structural characteristics and functional properties that are appealing for their use in diverse applications.

Review on the Production of Polysaccharide Aerogel Particles

“…Recently, León et al has demonstrated supercritical drying of chitosan-tripolyphosphate nanoparticles [185]. The nanoparticles diameter was in the range of 70 to 180 nm (polydispersity index = 0.36).…”

Size-controlled chitosan nanoparticles prepared using ionotropic gelation

“…Chitosan is a biopolymer obtained through the deacetylation of the chitin polysaccharide found in the exoskeletons of crustaceans. This biopolymer recognized as a cationic polymer consisting of β-(1-4)-D-glucosamine and N-acetyl-D-glucosamine groups [1,2] exhibits biocompatible, biodegradable, non-toxic, antimicrobial, adsorptive, and environmentally friendly properties [3][4][5][6]. These properties have made chitosan a widely investigated and developed material for use in a variety of fields, including pharmaceuticals, agriculture, biomedicine, and the chemical industry [4,[7][8][9].…”

“…The properties of chitosan depend on its molecular weight, degree of polymerization, degree of deacetylation, and particle size [3,10]. In regards to particle size, nanoscale chitosan particles exhibit remarkable properties in its application such as high adsorption capacity [6], increase cellular uptake and drug release [11] and alleviate toxicological effect [12].…”

Chemie der Chitosan‐Aerogele: Lenkung der dreidimensionalen Poren für maßgeschneiderte Anwendungen

“…Natriumtripolyphosphat ist einer der gebräuchlichsten ionischen Vernetzer für NH 3 + . [53,59,71,[80][81][82][83][84][85][86][87][88][89][90][91][92][93][94] Carbonsäuren wie Itaconsäure fungieren ebenfalls als ionische Vernetzer, [95] und anionische Polyelektrolyte wie Xanthan, [96,97] Alginat [97] und Polyglutaminsäure [98] ergeben mit Chitosan komplexe Strukturen durch NH 3…”

“…Das Eintropfen einer sauren Chitosanlçsung in ein alkalisches Bad ist wohl der einfachste Weg, um Gelperlen herzustellen, deren Grçße durch die der Tr opfen bestimmt ist. Die Grçße ist wiederum mithilfe von Dispersion, [83] elektrostatisch unterstützten Tr çpfchen [80] und Strahlschneidern kontrollierbar. [163,164] Die Herstellung von Perlen kann auch mit einer Sprühtrocknung verbunden werden.…”