The Effect of Polydimethylsiloxane-Ethylcellulose Coating Blends on the Surface Characterization and Drug Release of Ciprofloxacin-Loaded Mesoporous Silica

Abstract

In this study, we obtained novel solid films composed of ciprofloxacin-loaded mesoporous silica materials (CIP-loaded MCM-41) and polymer coating blends. Polymer coating blends were composed of ethylcellulose (EC) with various levels of polydimethylsiloxane (PDMS, 0, 1, 2% (v/v)). The solid films were prepared via the solvent-evaporation molding method and characterized by using scanning electron microscopy (SEM), optical profilometry, and wettability analyses. The solid-state of CIP present in the solid films was studied using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The release profiles of CIP were examined as a function of PDMS content in solid films. The surface morphology analysis of solid films indicated the progressive increase in surface heterogeneity and roughness with increasing PDMS content. The contact angle study confirmed the hydrophobicity of all solid films and significant impact of both PDMS and CIP-loaded MCM-41 on surface wettability. DSC and XRD analysis confirmed the presence of amorphous/semi-crystalline CIP in solid films. The Fickian diffusion-controlled drug release was observed for the CIP-loaded MCM-41 coated with PDMS-free polymer blend, whereas zero-order drug release was noticed for the CIP-loaded MCM-41 coated with polymer blends enriched with PDMS. Both the release rate and initial burst of CIP decreased with increasing PDMS content.

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“…The significant differences in surface morphology between the composites with PDMS (EC/PDMS/CIP and EC/PDMS/MCM-41-CIP) and without PDMS (EC/CIP and EC/MCM-41-CIP) were observed (Figure 2, insets I-IV). As previously reported [40], based on the optical profilometry results, the surface roughness of these composites increases as function of PDMS. Therefore, this phenomenon explained the differences in SEM surface results.…”

“…Moreover, the addition of PDMS into the polymer blend in EC/PDMS/MCM-41-CIP resulted in higher reduction of CIP burst release by the factor of 4.4 compared to EC/MCM-41-CIP (from 38.8 ± 3.1% to 8.8 ± 1.2%) ( Figure 4a). As described in our previous studies [38,40], the PDMS addition into the composites resulted in a prolonged drug release due to the occlusion of mesopores of drug-loaded silica particles by hydrophobic PDMS chains. The PDMS-occluded silica particles impeded the penetration of dissolution medium into the composites, and hence the further dissolution and release of drug loaded into the pores were slowed down.…”

“…The synthesis of MCM-41 was performed using sol-gel method as previously described [40] with the usage of TEOS as a silica source and cetyltrimethylammonium bromide (CTAB) cationic surfactant as a structure directing agent [36]. The water, ethanol, aqueous ammonia (25%), and CTAB in the amounts of 125, 12.5, 9.18 and 2.39 g, respectively, were mixed together in polypropylene beaker by stirring for 10 min (300 rpm, 25 • C) until complete dissolution of surfactant.…”

“…The ciprofloxacin (CIP) adsorption onto the mesoporous silica MCM-41 was carried out by using previously optimized procedure [40]. Briefly, MCM-41 material (particles fraction in the range of 200-500 µm) was suspended in the 10 mg/mL CIP lactate solution (pH = 3.5) using 50:1 mass to volume ratio.…”

“…However, in case of drug delivery systems, the results may be also related to the drug released into the cell culture medium. Therefore, CIP-free analogues such as EC#, EC/PDMS# and EC/PDMS/MCM-41# and various concentration of CIP aqueous solutions (10,20,40,80, 160 µg/mL) were also examined for comparative purposes. The frequently used proliferation tests based on addition of dyes (such as MTT or WST-1) may lead to false negative results due to unspecific interaction of the dye with tested material (e.g.…”