Zahra Ashurdokht - Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
Tahereh Tohidi Moghadam - Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
Bijan Ranjbar - Departments of Biophysics and Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University,Tehran, Iran.

Gold nanoparticles have shown promising applications in medical sciences, especially in drug delivery, due to presenting high biocompatibility. Today, many researchers havefocused on utilization of these nanoparticles as nanocarrier systems for small molecules such as proteins and drugs. Nevertheless, structure or conformation of proteins might experience irreversible and unfavorable changes upon interaction with gold nanoparticles, leading the loss of function and activity. Therefore, in this study, lysozyme has been selected as a model protein for small protein-based drugs and its structural changes has been investigated in the presence of gold nanoparticles. The biomolecule-nanoparticle complex was analysed using circular dichroism spectropolarimetry and UV-Vis spectroscopy. Further analysis was carried out in the presence of trehalose as a stabilizer. The results showed negligible changes in the secondary structure of lysozyme upon interaction with gold nanoparticles. Also, upon addition of trehalose, the helicity index of lysozyme-nanoparticles complex did not experience significant changes. Results of this investigation showed that gold nanoparticles can be considered as promising candidates in design and fabrication of the next generation of drug nanocarrier systems.

Lysozyme, Gold nanoparticles, Trehalose, Circular Dichroism Spectropolarimetry