Cytocompatibility and Uptake of Halloysite Clay Nanotubes

TLDR

Halloysite is an aluminosilicate clay with a hollow tubular structure, 50 nm in external diameter and 15 nm in lumen diameter. The study aimed to evaluate halloysite’s biocompatibility for potential use in polymer composites, bone implants, controlled drug delivery, and protective coatings. The authors incorporated halloysite nanotubes into various cell cultures for toxicity assays, functionalized them with APTES and fluorescent polyelectrolyte layers to monitor uptake via confocal laser scanning microscopy, and employed TEM, SEM, and SFM imaging to characterize the nanotube structure. Trypan blue and MTT assays on two cancer cell lines revealed that halloysite exhibits high biocompatibility and negligible cytotoxicity across concentrations and time points, indicating its suitability for household materials and medicine.

Abstract

Halloysite is aluminosilicate clay with hollow tubular structure of 50 nm external diameter and 15 nm diameter lumen. Halloysite biocompatibility study is important for its potential applications in polymer composites, bone implants, controlled drug delivery, and for protective coating (e.g., anticorrosion or antimolding). Halloysite nanotubes were added to different cell cultures for toxicity tests. Its fluorescence functionalization by aminopropyltriethosilane (APTES) and with fluorescently labeled polyelectrolyte layers allowed following halloysite uptake by the cells with confocal laser scanning microscopy (CLSM). Quantitative Trypan blue and MTT measurements performed with two neoplastic cell lines model systems as a function of the nanotubes concentration and incubation time indicate that halloysite exhibits a high level of biocompatibility and very low cytotoxicity, rendering it a good candidate for household materials and medicine. A combination of transmission electron microscopy (TEM), scanning electron microscopy (SEM), and scanning force microscopy (SFM) imaging techniques have been employed to elucidate the structure of halloysite nanotubes.