Methotrexate Intercalated CaAl Layered Double Hydroxide Nanohybrid for Drug Delivery

Abstract

The synthesis of CaAl-layered double hydroxide (CaAl-LDH) nanoparticles has been reported as a carrier of anticancerous drug, methotrexate (MTX) that has been intercalated into the LDH interlayer space by simple anion exchange technique. The insertion of the calcium ion, having larger ionic radius (114 pm) compared to the magnesium ion (86 pm) in the octahedral hole of the brucite layer in the previously reported MgAlLDH system, generated lattice strain, calculated by the well known Scherrer formula in XRD study. On intercalation of the drug molecule in the inter layer space, this strain as above was reduced substantially and an increase in its basal spacing was obtained. This was supported by the high resolution transmission electron microscopy data that exhibited a substantial enhancement in the interlayer spacing of LDH-MTX by 10.46 A (8.7 A in pristine LDH to 19.16 A in LDH-MTX). Further, increase in the decomposition temperature of the drug molecule from 290� C to 380� C indicate enhanced thermal stability of the drug molecule, being encapsulated in the LDH nanovehicle, as exhibited by the thermogravimetry analysis. The sustained release of the MTX drug for a prolonged period of 60 h, in phosphate buffer saline (PBS) at pH 7.4 followed Koresmeyers and Peppas model release kinetics via anomalous mechanism. The in vitro cytotoxicity study of LDH-MTX nanohybrid was carried out using MG-63 human osteosarcoma cell line, as per standard protocol, that exhibited inhibition of the cancer cell proliferation approximately two times for LDH-MTX compared to the MTX drug alone. To the best of our knowledge, this is the first ever report of the use of CaAl-LDH as carrier for delivery of a toxic anticancer drug, methotrexate.