Hydrothermal synthesis and characterization of magnetic Fe3O4 and APTS coated Fe3O4 nanoparticles: physicochemical investigations of interaction with DNA.

Magnetic nanoparticles (MNPs) especially iron oxide (Fe3O4) NPs have quite extensively been used for in vivo delivery of biomolecules and drugs because of their high bioconjugation efficiency. In this study, Fe3O4 NPs and (3-Aminopropyl) triethoxysilane (APTS) coated Fe3O4 NPs were synthesized and their interaction with Calf thymus (Ct) DNA has been studied in order to understand their usage in biomedical applications. Hydrothermal method was used for the NPs synthesis. Characterization of NPs was done using techniques like UV-Visible spectroscopy, FTIR spectroscopy, FE-SEM, EDAX, Zeta Sizer and powder XRD. Further, interaction studies of NPs with Ct-DNA were investigated using various physicochemical techniques. In UV-Visible studies, hypochromicity with binding constant 3.2 × 105 M-1 was observed. Binding constants calculated using fluorescence studies were found to be k = 3.2 × 104 M-1, 2.9 × 104 M-1 at 293 and 323 K respectively. Results of UV-Visible and fluorescence studies were in correlation with other techniques like UV-TM and CD. All studies suggested alteration in DNA conformation on interaction with surface engineered Fe3O4 NPs, stabilizing DNA-NPs conjugate via partial intercalation and electrostatic interactions. This study may facilitate our understanding regarding the physicochemical properties and DNA-binding ability of APTS-Fe3O4 NPs for their further application in magnetosensitive biosensing and drug delivery. Iron oxide based magnetic nanoparticles are well known for their excellent bio-conjugation efficiency and therefore APTS-Fe3O4 NPs were synthesized via very simple and benign hydrothermal method. Further, the interaction of APTS-Fe3O4 NPs with calf thymus DNA was studied using various physicochemical techniques to explore their potential in biomedical applications.