Introduction: Different anti-cancer carrier and delivery systems were developed over time. Recently montmorillonite clay particles are combined with polymers in order to create an advanced network for a better modulation of drug release. In this study the cytotoxicity effect induced by natural montmorillonite, Cloisite®Na+ and the organically modified ones, Cloisite®30B and Cloisite®93A over time on two cell lines, MDBK and HT29 was assessed.
Methods: All mentioned clays (Southern Clay Products Inc.) were characterized by FTIR and TGA analysis. The diameter size and the polydispersity index (PDI) were determined by DLS using a ZetaPlus instrument. Cellular viability and proliferation of normal MDBK and colon adenocarcinoma HT29 cells untreated or treated with different concentrations of clays (31.25μg/ml- 500μg/ml) was evaluated using a colorimetric non-radioactive assay (MTS). Morphology of cells exposed to clays was monitored in time using bright field microscopy technique, using TissueFAXSiPlus imaging system.
Results: FTIR spectra revealed specific peaks for montmorillonite clays. TGA curves of commercial clay indicate three steps of weight loss. The z-average mean of all types of cloisite was between 2000-3000 nm. PDI, reflecting the particle size distribution in each suspension variant indicated values between 0.226 and 0.292. The shape of DLS graphs also confirmed that all variants of clays were polydisperse and had a tendency to form aggregates. The MTS assay revealed that after 24 and 48 hours of exposure, irrespective of cloisite type, high concentrations of clay particle present significant cytotoxic properties probably due to the aggregate formation which cover cell monolayer and inhibit cell proliferation. Treatment with 31.25μg/ml of Cloisite®93A for up to two days showed the highest viability on both cell lines compared with control (untreated cell), results confirmed by cell morphology analysis under the light microscope.
Conclusions: The present findings show that Cloisite®93A might be a good candidate for incorporation in a complex biopolymer semi-interpenetrated networks for the improvement of chemotherapeutic drug delivery into gastrointestinal tract.
Acknowledgement: This work was supported by a grant of the Romanian National Authority for Scientific Research and Innovation, CNCS/CCCDI-UEFISCDI, project number PN-III-P2-2.1-PED-2016-1896 and Romanian Academy Project 3 of the Institute of Biochemistry/2017.
