Surface-Activated Fibre-Like SBA-15 as Drug Carriers for Bone Diseases

Magdalena Prokopowicz,Adrian Szewczyk,Adrianna Skwira,Jacek Żeglinski,Gavin Walker

doi:10.1208/s12249-018-1243-5

Magdalena Prokopowicz, Adrian Szewczyk + Show 3 more

Open Access

https://doi.org/10.1208/s12249-018-1243-5

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Abstract

Here, we report an inorganic hexagonally ordered mesoporous fibre-like carrier made of silica as an effective drug delivery system with mineralisation potential. Fibre-like SBA-15 has been modified by employing a simple surface activation (rehydroxylation) procedure. The surface-rehydroxylated fibre-like SBA-15 (SBA-15-R) was used to investigate the possible mechanism of hydroxyapatite (HA) nucleation and deposition onto silica’s surface after immersion in simulated body fluid (SBF). Amorphous calcium phosphate, Ca-deficient HA and bone-like HA deposits were observed on SBA-15-R surface consecutively after 7, 14 and 21 days of immersion in SBF. Accordingly, our low-angle XRD, STEM and N2 adsorption/desorption results indicated that deposited ions were mostly located at the silica’s surface and could modify the size of the mesopores. The SBA-15-R was studied in vitro as the potential bioactive drug delivery system using doxorubicin (DOX) as a model water-soluble and anticancer drug. The adsorbed DOX molecules were mostly located at the pore walls and pore openings, likely together with the silanol groups. The DOX release was diffusion-controlled and relatively slower in SBF (pH = 7.4) than in phosphate-buffered solution (pH = 5.0), most probably due to both the stronger electrostatic interactions occurring between the DOX and the SBA-15-R and the simultaneous deposition of calcium and phosphates ions from SBF.

Highlights

The development of new local drug carriers for bone diseases focuses on enhanced bioactivity—mineralisation potential, higher delivery efficiency, lower toxicity and controlled drug release
The corresponding values calculated per surface area (765 m2/g for SBA-15 and 680 m2/g for SBA15-R) were 2.0 ± 0.3 and 5.0 ± 1.0 μmol/m2 for SBA-15 and SBA-15-R, respectively, showing that after rehydroxylation, the accessible surface concentration of silanols increased by factor of 2.5
Fibre-like hexagonally ordered mesoporous silica SBA-15 has been successfully modified by employing a simple surface activation procedure

Summary

Introduction

The development of new local drug carriers for bone diseases focuses on enhanced bioactivity—mineralisation potential, higher delivery efficiency, lower toxicity and controlled drug release. The potential role of HOMS in formulating local drug carriers for bone diseases is emphasised in several studies [1,2,3]. The apatite layer that formed on a surface of the silica immersed in SBF usually features low to medium crystallinity, similar to that of the bone tissue apatite. This phenomenon has been recently explored as a potential way of generating in situ biomimetic HA coatings onto the implantable drug carriers [10]

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