Biomimetic Growth of Hydroxyapatite on SiO2 Microspheres to Improve Its Biocompatibility and Gentamicin Loading Capacity.

Alejandra E Herrera-Alonso,Antonia Martínez-Luévanos,Luis A García-Cerda,Sofía Estrada-Flores,Sandra C Esparza-González,María C Ibarra-Alonso

doi:10.3390/ma14226941

Alejandra E Herrera-Alonso, Antonia Martínez-Luévanos + Show 4 more

Open Access

https://doi.org/10.3390/ma14226941

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Abstract

The interest in multifunctional biomaterials to be implanted are also able to release drugs that reduce pain and inflammation or prevent a possible infection has increased. Bioactive materials such as silica (SiO2) containing surface silanol groups contribute to the nucleation and growth of hydroxyapatite (HAp) in a physiological environment. Regarding biocompatibility, the spherical shape of particles is the desirable one, since it does not cause mechanical damage to the cell membrane. In this work, the synthesis of SiO2 microspheres was performed by the modified Stöber method and they were used for the biomimetic growth of HAp on their surface. The effect of the type of surfactant (sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide (CTAB), and polyethylene glycol (PEG)), and heat treatment on the morphology and size of SiO2 particles was investigated. Monodisperse, spherical-shaped SiO2 microparticles with an average particle size of 179 nm, were obtained when using PEG (SiO2-PEG). The biomimetic growth of HAp was performed on this sample to improve its biocompatibility and drug-loading capacity using gentamicin as a model drug. Biomimetic growth of HAp was confirmed by FTIR-ATR, SEM-EDX and TEM techniques. SiO2-PEG/HAp sample had a better biocompatibility in vitro and gentamicin loading capacity than SiO2-PEG sample.

Highlights

Bone is the only part of the body with the capacity to regenerate, this bone regeneration generally requires three processes: osteoconduction, osteoinduction, and osteogenesis [1,2]
The best sample was selected to induce the biomimetic growth of HAp and carry out the biocompatibility analysis, as well as the gentamicin load
The results of the infrared spectroscopy of the different samples analyzed are shown in Figure 1a, which presents the infrared spectra of the three silica samples obtained, varying the type of surfactant (PEG, CTAB, and SDS)

Summary

Introduction

Bone is the only part of the body with the capacity to regenerate, this bone regeneration generally requires three processes: osteoconduction (in which the graft material provides an appropriate physical environment for new bone creation), osteoinduction (encourages active osteoblasts to stimulate osteogenesis), and osteogenesis (new bone formation from cells derived from the graft or the host) [1,2]. Silanol groups (Si–OH) on the surface of SiO2 provide effective sites for nucleation and biomimetic growth of HAp, which has been widely reported to be biocompatible [10,11,12,13]. In a simulated body fluid (SBF), with plenty of Ca2+ and PO43− ions, HAp formation can be explained by the presence of Si–OH groups. Silanol (Si–OH) can bind to the Ca2+ ions present in the SBF solution, forming a calcium silicate and providing a positive charge on the silica surface, which will attract PO43− groups giving rise to calcium phosphate. HAp nuclei formation is facilitated with this process, which occurs spontaneously, consuming Ca2+ and PO43− ions present in SBF solution [7,12,13]

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