To increase the long-term stability of poly(D,L-lactide-co-glycolide) nanoparticles (NP) a drying step is mandatory. Spray- and freeze-drying can induce their irreversible aggregation and, therefore, the use of a drying auxiliary agent is necessary. The aim of this work was to explore the ability of four grades of maltodextrins (MDX) as NP’s auxiliary agent in spray- and freeze-drying. PLGA NP were prepared by the solvent displacement method, using a polymer with a Tg of 36.5 °C. Compatibility was evaluated by DLS, after stirring NP with solutions of MDX (DE2, DE6, DE12 and DE38) at 2, 4 and 8% w/v concentrations using water or 0.9% NaCl as dispersants. Spray-drying process conditions were optimized by a Design of Experiment. Freeze-drying cycles were designed based on the thermal properties of MDX solutions. Dried products were reconstituted in water or 0.9% NaCl under gentle stirring and characterized by DLS after 5, 30 and 60 min. NP had a monomodal size distribution with a size of about 160 nm and a Z-potential (z) of -31 mV. NP were compatible with all the aqueous solutions of MDX at all concentrations, even if DLS revealed a slight increment of NP size as a function of MDX grade and concentration. A concomitant increase of z was less evident for MDX DE2 and DE38 compared to DE6 and DE12, with values of about -26 and -24 mV, respectively. In 0.9% NaCl solution, only MDX DE2 and DE38 did not induce NP aggregation. These results appeared related to the organization of MDX onto NP surface, since both the z and the apparent persistence length of hydrated MDX  followed the same trend. Independently of the drying method, after reconstitution of the dried products, MDX DE2 was not effective in preserving NP features (size>400 nm). Conversely, MDX DE38 allowed an easy and complete reconstitution of NP. Its optimal concentrations resulted in the 2-4% w/v range. Indeed, monodisperse NP were obtained after 5 min of reconstitution independently of medium ionic strength (spray-dried product prepared by 2%w/v MDX DE38: 172±12 nm; freeze-dried product prepared by 4%w/v MDX DE38: 188±6 nm). In conclusion, MDX DE38 appears an efficacious drying auxiliary agent for NP at concentrations lower than those reported in literature for polyols and sugars, independently of the drying process. References  Aeberhardt K., De Saint Laumer J.Y., Bouquerand P.E., Normand V. Ultrasonic wave spectroscopy study of sugar oligomers and polysaccharides in aqueous solutions: The hydration length concept. International Journal of Biological Macromolecules, 36(5), 275–282, 2005.
Maltodextrins as drying auxiliary agent for the preparation of easily resuspendable nanoparticles / G. Magri. ((Intervento presentato al convegno Summer school in Innovation in local drug delivery tenutosi a Como nel 2018.
|Titolo:||Maltodextrins as drying auxiliary agent for the preparation of easily resuspendable nanoparticles|
MAGRI, GIULIA (Primo) (Corresponding)
|Data di pubblicazione:||27-set-2018|
|Settore Scientifico Disciplinare:||Settore CHIM/09 - Farmaceutico Tecnologico Applicativo|
|Citazione:||Maltodextrins as drying auxiliary agent for the preparation of easily resuspendable nanoparticles / G. Magri. ((Intervento presentato al convegno Summer school in Innovation in local drug delivery tenutosi a Como nel 2018.|
|Appare nelle tipologie:||14 - Intervento a convegno non pubblicato|