Cellular uptake and imaging studies of glycosylated silica nanoprobe (GSN) in human colon adenocarcinoma (HT 29 cell line)

Bita Mehravi,¹ Mohsen Ahmadi,¹ Massoud Amanlou,² Ahmad Mostaar,¹ Mehdi Shafiee Ardestani,³ Negar Ghalandarlaki<sup>4

1</sup>Biomedical 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, Tehran, Iran; ⁴Department of Biological Science, School of Science, Science and Research branch, Islamic Azad University, Tehran, Iran

Purpose: In recent years, molecular imaging by magnetic resonance imaging (MRI) has gained prominence in the detection of tumor cells. The scope of this study is on molecular imaging and on the cellular uptake study of a glycosylated silica nanoprobe (GSN).
Methods: In this study, intracellular uptake (HT 29 cell line) of GSN was analyzed quantitatively and qualitatively with inductively coupled plasma atomic emission spectroscopy, flow cytometry, and fluorescent microscopy. In vitro and in vivo relaxometry of this nanoparticle was determined using a 3 Tesla MRI; biodistribution of GSN and Magnevist^® were measured in different tissues.
Results: Results suggest that the cellular uptake of GSN was about 70%. The r₁ relaxivity of this nanoparticle in the cells was measured to be 12.9 ± 1.6 mM^-1 s^-1 and on a per lanthanide gadolinium (Gd³⁺) basis. Results also indicate an average cellular uptake of 0.7 ± 0.009 pg Gd³⁺ per cell. It should be noted that 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay demonstrated that the cells were effectively labeled without cytotoxicity, and that using MRI for quantitative estimation of delivery and uptake of targeted contrast agents and early detection of human colon cancer cells using targeted contrast agents, is feasible.
Conclusion: These results showed that GSN provided a critical guideline in selecting these nanoparticles as an appropriate contrast agent for nanomedicine applications.

Keywords: cellular uptake, contrast agent, glucosamine, mesoporous silica nanospheres, molecular imaging, MRI