Development and characterization of clay-polymer nanocomposite membranes containing sodium alendronate with osteogenic activity

The preparation of new biocompatible polymer systems could accelerate processes underlying guided bone tissue regeneration (GBR) by acting as adjuvants. Here, different reaction conditions were investigated to engineer nanocomposites based on chitosan and sodium montimorilonite (Na-Mt) that can be used to generate biocompatible membranes. The goal was a balanced combination of flexibility and tensile strength for use in orthopedic and periodontal surgical procedures for improved GBR. The execution of different experimental protocols aimed to control the polymer intercalation process inside the Na-Mt lamellae, and to avoid their exfoliation, by varying its concentration while applying, at same time, ultrasonic energy as a pretreatment. To increase the therapeutic efficacy of the membranes formed, sodium alendronate was included in the compositions as well as plasticizers to optimize their mechanical and physical-chemical properties. All membranes were analyzed by powder x-ray diffraction, nuclear magnetic resonance, differential scanning calorimetry and thermogravimetric analysis, as well as high performance chromatography to characterize the sodium alendronate content. Surface roughness, water absorption (swelling) and tensile strength were evaluated by scanning electron microscope and profilometry. As a model for human osteoblasts, the proliferation of Saos-2 cells was measured by colorimetric assays and microscopy to assess the potential performance of the membranes in GBR. Membranes with improved mechanical and physical-chemical properties along with excellent biocompatibility could be generated from 33% sodium montmorillonite (w/w) intercalated with chitosan and containing sodium alendronate, glycerol (20% [w/w]) and Labrasol® (3% [w/w]) that also supported the induction of Saos-2 cell proliferation and differentiation, exhibiting potential to develop a novel biomaterial device for GBR