Conjugation of glucosamine with Gd3+-based nanoporous silica using a heterobifunctional ANB-NOS crosslinker for imaging of cancer cells

Abstract

Bita Mehravi,1 Mohsen Ahmadi,1 Massoud Amanlou,2 Ahmad Mostaar,1 Mehdi Shafiee Ardestani,3 Negar Ghalandarlaki4 1Biomedical Engineering and Medical Physics Department, Faculty of Medicine, Shahid Beheshti University of Medical Sciences,Tehran, Iran; 2Department of Medicinal Chemistry, Faculty of Pharmacy and Drug Design and Development Research Center, Tehran University of Medical Sciences, Tehran, Iran, 3Department of RadioPharmacy, Faculty of Pharmacy, Tehran University of Medical Sciences, 4Department of Biological Science, School of Science, Science and Research Branch, Islamic Azad University, Tehran, Iran Background: The aim of this study was to synthesize Gd3+-based silica nanoparticles that conjugate easily with glucosamine and to investigate their use as a nanoprobe for detection of human fibrosarcoma cells. Methods: Based on the structure of the 2-fluoro-2-deoxy-D-glucose molecule (18FDG), a new compound consisting of D-glucose (1.1 nm) was conjugated with a Gd3+-based mesoporous silica nanoparticle using an N-5-azido-2-nitrobenzoyloxy succinimide (ANB-NOS) crosslinker. The contrast agent obtained was characterized using a variety of methods, including Fourier transform infrared spectroscopy, nitrogen physisorption, thermogravimetric analysis, scanning and transmission electron microscopy, and inductively coupled plasma atomic emission spectrometry (ICP-AES). In vitro studies included cell toxicity, apoptosis, tumor necrosis factor-alpha, and hexokinase assays, and in vivo tests consisted of evaluation of blood glucose levels using the contrast compound and tumor imaging. The cellular uptake study was validated using ICP-AES. Magnetic resonance relaxivity of the contrast agent was determined using a 1.5 Tesla scanner. Results: ANB-NOS was found to be the preferred linker for attaching glucosamine onto the surface of the mesoporous silica nanospheres. The r1 relaxivity for the nanoparticles was 17.70 mM-1s-1 per Gd3+ ion, which is 4.4 times larger than that for Magnevist® (r1 approximately 4 mM-1s-1 per Gd3+ ion). The compound showed suitable cellular uptake (75.6% ± 2.01%) without any appreciable cytotoxicity. Conclusion: Our results suggest that covalently attaching glucosamine molecules to mesoporous silica nanoparticles enables effective targeted delivery of a contrast agent. Keywords: gadolinium, glucosamine, mesoporous silica nanospheres, magnetic resonance imaging, N-5-azido-2-nitrobenzoyloxy succinimide, photoactivation