Comparison of Drug Loading Capacities of Mg Al Layered Double Hydroxides Synthesized via Soft Template Method Using Different Aging Conditions

Abstract

Background: Template directed synthesis of Layered double hydroxides (LDH) has gained much attention as the removal of the template results in a porous LDH material with large surface area which leads to high drug loading. Objectives: To synthesize Mg-Al LDHs via template-directed synthesis using different aging conditions followed by calcination, to load prepared LDH samples with diclofenac sodium and to compare drug loading capacities of these composites Methods: Templated Mg Al LDHs (TLDH1, TLDH2) were synthesized using sodium dodecyl sulphate (SDS) and poly vinyl pyrrolidone (PVP). TLDH1 was aged at 60°C in an oven for 20 h and TLDH2 was aged at 135 °C for 4 h hydrothermally in an autoclave. Samples were calcined at 500°C for 5 h to remove the template and the LDH structure was regenerated using an ethanolic solution of diclofenac sodium (TLDH1-R-D, TLDH2-R-D). Corresponding pristine LDL samples were synthesized following the same procedure without the template (LDH1, LDH2). Prepared LDHs were characterized using x-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) techniques. Drug loading capacities of prepared LDHs were analysed. Results: The XRD spectra of prepared LDHs exhibited characteristic diffraction peaks corresponding to (003), (006), (009), (015), (018), (110), and (113) planes revealing a successful synthesis of pure LDH layers. Changing the reaction conditions resulted in the Mg-Al LDHs with different degrees of crystallinity and crystal size. Samples prepared via PVP-SDS template method showed high drug loading, compared to corresponding pristine LDH samples. Moreover, the drug loading capacity of TLDH2-R-D, showed higher drug loading capacity (51.3%) compared to TLDH1-R-D (41.9%). Conclusions: Mg-Al LDH nanocarriers having high drug loading capacity could be successfully synthesized using PVP-SDS template. Drug loading capacity could be increased by aging the samples hydrothermally (135°C). Keywords: Drug loading, Layered double hydroxides, Poly Vinyl Pyrrolidone, Sodium Dodecyl Sulphate, Template 48