Biological Activity of Surface Modified Nanocrystals

Background: Considerable interest is observed in the usage of nanomaterials in medicine and medical diagnostics. Quantum dots powerful fluorescent probes, seem to be interesting agents for medical imaging that could be used to label cells for cellular tracing as well as for traceable drug/gene delivery. It is expected that their use can be crucial in pharmacokinetic and pharmacodynamic studies of drug candidates. However, their widespread and safe use must be preceded by examination of their toxicity. Method: A group of quantum dots (CdS, CdSe, CdTe), which contains cadmium ions in its core composition has been chosen for biological activity studies – examination the effect of surface chemistry for their toxicity (MTT test). Result: Quantum dots usually are hydrophobic due to inorganic core with chains of hydrophobic ligands (TOP/TOPO) remaining after synthesis. Exchange of the ligand for the hydrophilic one enables dispersion of QD in water, application to the living organisms and assessment of their influence using in vitro models. In this study, we report how modification of the surface of CdX quantum dots (with and without ZnS coating) affects their biological activity. Conclusion: Three different ligands (cysteine, dihydrolipoic acid-DHLA, and mercaptoundecanoic acid-MUA) and two cell lines MRC-5 and A549 (similar origin and function, different proliferation – one was normal, another was carcinoma) were used to test thoroughly biological activity of surface- modified CdX quantum dots.