Poly-Caprolactone Nanocapsules Morphological Features by Atomic Force Microscopy

Abstract

Polymeric nanoparticles containing an oily core, named nanocapsules (NCs), have been widely studied in the life sciences field due to their therapeutic potentialities of drug targeting in the body accompanied also by its larger stability in the biological fluids compared to other colloidal carriers. Many studies have shown different applications of nanocapsules for therapeutic use concerning their properties [1] of loading poorly water-soluble drugs, protection drugs from inactivation in the gastro-intestinal tract [2], gastric mucosal toxicity protection [3,4], increased drug permeation through mucous epithelium [5,6] and prolongation of drugs in blood circulation for surface modified nanocapsules [7]. The characterization of the nanocapsules is frequently performed by mean size, surface charge of the particles (zeta potential), hydrophobicity, drug loading yield and release kinetic [8]. These features are of great importance for biodistribution profile and interactions with the cells of mononuclear phagocyte system of any injected particles by intravenous route [1]. However, few data on structural organization of the nanocapsules constituents are available in literature and several hypotheses only suggest the presence of an oil "capsular" structure surrounded by a polymeric envelope. Recently, atomic force microscope (AFM) has been used as a method for imaging the surfaces of colloidal systems, such as liposomes [9,10] and nanospheres [11], supplying high resolution information in nanoscaled dimension. In the present work, unloaded nanocapsules were deposited on mica in order to analyze by AFM the diameter, height, particles polydispersion, and topographic characteristics of nanocapsule surface.

Characterization and in vivo evaluation of nanocapsules loading 99mTc-MIBI for intramammary study

“…This observation can be explained by a possible NC flattening and aggregation process that takes place after drying on a glass surface. In fact, the flattening phenomenon was probably related to variations in polymeric wall thickness and in its homogeneity, and it is in accordance with previous works [6,22,26]. The diameter/height ratios were calculated from the topographical profile of AFM.…”

“…Values obtained in this study showed a diameter/height ratio of 12 ± 2 and 8 ± 1 for unloaded PCL NC and CS-PCL NC, indicating that the presence of CS increased the hardness of the polymeric wall, as its value is lower. Similarly to this work, Leite et al [26] and de Assis et al [6] observed a ratio of approximately 10 for PCL NC and PLA NC, respectively. When 99m Tc-MIBI was associated with the NC, the diameter/height ratios decreased to values of 4 ± 0.1 and 7 ± 1, for 99m Tc-MIBI-PCL NC and 99m Tc-MIBI-CS PCL NC, respectively.…”

Impact of dose and surface features on plasmatic and liver concentrations of biodegradable polymeric nanocapsules

“…AFM analysis in tapping mode requires only mild experimental conditions suitable for probing soft samples. Vesicular polymeric nanostructures containing an oily core have already been successfully analysed and their vesicular structure was confirmed by this method (de Assis et al, 2008;Garcia et al, 2015;Leite et al, 2005;Mosqueira et al, 2005;Pereira et al, 2008). Phase images of our NC (Figure 3) revealed differences in stiffness of the NC core (dark regions) surrounded by a shell (lighter layer).…”

Desenvolvimento de método analítico por eletroforese capilar para quantificação de éster do ácido pirazinóico em nanosuspensão

“…4) (SCHAFFAZIK et al, 2003;SOUTO et al, 2012). (BENDER et al,2012;KHAYATA, et al, 2012;LEITE et al, 2005;MÜLLER et al, 2001;NECKEL & LEMOS-SENNA, 2005;SOUTO et al, 2012).…”

“…(Adaptado de SCHAFFAZICK, et al, 2003) Nanocápsulas apresentam vantagens por terem propriedades mais flexíveis que outras nanopartículas poliméricas, transpondo espaços entre células como o endotélio vascular, além da alta estabilidade em fluídos biológicos comparadas a outros carreadores coloidais. Nanocápsulas (NCs) também têm vantagens sobre os demais sistemas no emprego em substâncias sensíveis a temperaturas acima de 40 °C e a fotodegradação(LEITE et al, 2005; MULLER et al, 2004).Em um estudo de fotoestabilidade da tretinoína, Ourique et al(2008) verificaram que suspensões de NCs contendo tretinoína apresentaram meia-vida superior a solução metanólica do fármaco e que a tretinoína contida nas NCs apresentaram menor fotodegradação. Contri et al(2011) relatam em um estudo de controle de liberação de capsaicinóides contidos em NCs, um aumento no efeito analgésico dos capsaicinóides e uma diminuição na sensação de queimação na pele.…”