Thiahelicene-grafted halloysite nanotubes: Characterization, biological studies and pH triggered release

• Published in: Applied surface science Vol. 520; p. 146351
• Main Authors: Taroni, Tommaso, Cauteruccio, Silvia, Vago, Riccardo, Franchi, Stefano, Barbero, Nadia, Licandro, Emanuela, Ardizzone, Silvia, Meroni, Daniela
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2020
• Subjects: Halloysite nanotubes; Helicene; Nanocarrier; NEXAFS; Triggered release; Helicene; NEXAFS; Nanocarrier; Triggered release; Halloysite nanotubes
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2020.146351

[Display omitted] •Thiahelicene was covalently bound to halloysite nanotubes as new drug delivery system.•Grafting mode and release mechanism were studied by combined surface spectroscopies.•Thermal and spectroscopic methods clarified surface density and molecule orientation.•pH-dependent release of thiahelicene was verified in a range of physiological values.•Cytotoxicity was tested on two tumoral cell lines with different culture medium pH. A novel drug delivery nanosystem was here designed, linking thiahelicenes to halloysite nanotubes. Tetrathia[7]helicenes are very promising DNA intercalators, whose usage in biomedical field has been so far limited by their poor bioavailability. The study of appropriate drug delivery systems is needed to exploit helicenes as therapeutics. In this work, imine chemistry was adopted to covalently attach the bioactive compound and release it in acidic environments such as those surrounding tumour cells. To this aim, halloysite nanotubes were functionalized with (3-aminopropyl)triethoxysilane. The latter acted as linker providing NH2 groups to react with the formyl moiety of the thiahelicene derivative. The nanoconstruct preparation was studied in depth by surface-sensitive spectroscopies and angle-resolved X-ray absorption, to investigate the attachment mode, surface coverage and molecular orientation of the thiahelicene units. Release tests were carried out also in vitro on two tumour cell lines with different extracellular pH values. Mildly acidic pH conditions catalyzed the hydrolysis of the imine bond and promoted the cytotoxic compound release, which proved selective to slight pH differences, confirming the potential of this novel nanoconstruct.