ABSTRACT
Recent development in nano-biotechnology shows that protein–nanoparticle (P-NP) interactions dictate the behaviour of the NPs in the surrounding bio-systems. As NPs enter biological fluids, biomolecules (majorly proteins) adsorb to their surfaces leading to the corona formation (protein corona PC) which influences the structure and bioactivity of proteins. Hydroxyapatite (HAp; Ca10(PO4)6(OH)2, Ca/P in the molar ratio 1.67), an essential component of bones and teeth, have emerged as a new type of biomaterials due to its outstanding biological properties. Recent reports have shown that the synergistic effect of the magnetic nanomaterial in the hydroxyapatite nanostructures provide effective means for biomedical applications. The present study focusses on the synthesis of HAp NPs and Fe doped HAp NPs (DHAp-NPs). The synthesized NPs were characterized using X-Ray diffraction, Attenuated Total reflection-Fourier-transform infrared spectroscopy and Transmission Electron Microscopy. The interaction of synthesized HAP & DHAp NPs with proteins was investigated with and without prior surface functionalization by Cetyl Pyridinium Chloride (CPC) and tri-lithium citrate (TLC) having Cl- and Li+ as the corresponding counter-ions. Pepsin A and Hen Egg White Lysozyme (HEWL) were used as negatively and positively charged model proteins respectively. The P-NP interaction was characterized by Dynamic light scattering, Zeta-potential measurements, UV-visible absorption and fluorescence emission spectroscopy. The secondary structure of the protein was investigated using circular dichroism spectroscopy. The functionality of the protein upon interaction with HAp and DHAp was verified using enzymatic assays.
