Synthesis, characterization and chlorhexidine release from either montmorillonite or palygorskite modified organoclays for antibacterial applications

Abstract Characterization of clay-drug hybrid materials for antibacterial applications using montmorillonite (MMT) and chlorhexidine diacetate (CA) has been reported; however, antibacterial clays based on palygorskite (PLG) have not been explored. Organoclays based on MMT (a laminar clay) and palygorskite (a microfibrous clay), are expected to differ in their chlorhexidine release profiles as the relevance of a specific mechanism depends on several factors. Therefore, CA was incorporated at various concentrations (50, 100 and 200% of Cation Exchange Capacity, CEC) and the resulting organoclays were characterized by Energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X-Ray Diffraction (XRD), and Thermogravimetric Analysis (TGA). In addition, in vitro release studies of CA from organoclays were carried out in phosphate buffered saline (PBS) media. EDS FTIR and TGA results confirmed that CA was successful incorporated into these nanoclays. XRD patterns of CA/MMT show an increase in d -spacing of MMT as CA concentration was increased suggesting CA intercalation within the MMT galleries; in contrast, the diffraction peak of CA/PLG remained unchanged upon the CA modification. The drug release studies showed an initial burst release within the first 5 h and then a sustained release of CA up 24 h. CA released from MMT system was higher that observed for PLG ones.