Abstract
In this study, the effect of the ionic cross-linking mode on the ability to control physical properties and in vitro release behavior of the dexamethasone (DEX) drug from chitosan (CS) and chitosan/hydroxyapatite (CS/HA) beads was investigated. CS solutions without and with HA and DEX were dripped into two coagulation solutions, prepared with a non-toxic ionic crosslinker (sodium tripolyphosphate, TPP) and distilled water, one at pH = 9.0 and other at pH = 6.0. Optical microscopy (OM) and scanning electron microscopy (SEM) results showed changes on the surface topology of the beads, with a reduction of roughness for beads prepared at pH = 6.0 and an increase for the one prepared at pH = 9.0. The diameter and sphericity of the beads prepared at pH = 6.0 proved more uniform and had a larger pore size with a good interconnectivity framework. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) suggested a higher crosslinking degree for beads prepared at pH = 6.0, corroborated by X-ray diffraction profiles (XRD) analysis that indicated a decrease in the crystalline structure for such beads. In in vitro drug release data, all beads presented a sustained release during the studied period (24 h). The drug release rate was affected by the pH of the coagulation solution used in the preparation of the beads. The in vitro kinetics of the release process was of the Peppas–Sahlin model, controlled by both diffusion and relaxation of polymer chains or swelling (anomalous transport mechanism). Our results suggest that DEX-loaded CS/HA beads, crosslinked in TPP coagulation solution at pH = 9.0, led to a decrease in the DEX release rate and prolonged the release period. Thus, this composition might have prospective as a functional material for bone and cartilage tissue engineering.
Highlights
Polymeric material suitable for biomedical applications must be biocompatible and biodegradable [1]
The objective of this study was to prepare chitosan beads with hydroxyapatite loaded with the dexamethasone drug by ionotropic gelation method and to evaluate the interactions of materials and possible differences related to pH, to be used as a basis for the manufacture of scaffolds in biomedical applications, including controlled drug release systems for bone regeneration
Optical microscopy studies revealed that the pH of TPP solution used to Optical microscopy studies revealed that the pH of TPP solution used to fabricate CS beads was found to affect their morphology (Figure 1)
Summary
Polymeric material suitable for biomedical applications must be biocompatible and biodegradable [1]. Chitosan can be modified in different ways to control the rate of release and efficiency of the bioactive agent in the delivery systems, for example, from cross-linked beads [4]. The practice of the beads-based delivery system allows control of the drug release profile and the specific target site by carefully adapting the formulation of various drug combinations and polymeric materials. This type of delivery system provides longer life, controlled release rate, and in addition, directs the specific drug. There are different methods for forming beads, for example, interaction with counterions, such as anions (sulfate, phosphates, hydroxides), cross-linking, solvent evaporation, ionic gelling, spray drying, emulsion polymerization, and precipitation, etc. [6]
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