Cell and Tissue Journal

Abstract Aim: Cancer is a global concern and colorectal cancer (CRC( accounts for the second most common cause of cancer related death in the world. Nanotechnology could enhance the effectiveness of chemotherapy as a common therapeutic approach through development of smart nanoparticles (NPs). In this context, theranostic nanoparticles with both imaging and therapeutic potentials are considered as promising platforms in diagnosis and treatment of advanced cancers.
Materials & Methods: Here, we designed and synthesized magnetic mesoporous silica nanoparticles (SPION-MSNs) in which release of 5-fluorouracil (5-FU) at physiological conditions was inhibited with pH-responsive gold gatekeepers. Heterofunctional polyethylene glycol (PEG) polymer was then conjugated onto the outer surface of nanoparticles and non-targeted nanoparticles were successfully synthesized. In order to achieve active and specific targeting, non-targeted nanoparticles were armed with an epithelial cell adhesion molecule (EpCAM) aptamer (Apt) for selective drug delivery of 5-FU to colorectal cancer cells. Finally, the physicochemical properties of NPs including functional groups, surface charge and their size were fully characterized with Fourier transform infrared (FTIR) spectra and dynamic light scattering (DLS) in each step. Moreover, morphology and homogeneity of SPION-MSNs were evaluated using field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HR-TEM) and atomic force microscopy (AFM). The cumulative release of 5-FU from nanoparticles was compared in buffer solutions with two different pH values (pH 7.4 and 5.4). In the final step, anti-cancer potential and cytotoxicity of free 5-FU, non-targeted, and targeted nanoparticles were assessed on human colorectal adenocarcinoma HT-29 cells and Chinese hamster ovary cells.
Results: Core-shell NPs, SPION-MSNs, were successfully prepared and the FTIR spectra showed specific peaks at the surface of nanoparticles. Obtained results from DLS measurements showed that the synthesized formulation had negative charges with size of 20 nm. Moreover, the morphology of SPION-MSNs indicated spherical shape with uniform distribution. After introducing amine groups, the surface charge was shift to positive and the two bands at 2965 and 1,560 cm⁻¹ in the FT-IR spectrum were appeared and assigned to CH₂-CH₂ and N-H groups, respectively. The results indicated, 5-FU was encapsulated in the open pores of MSNs and the encapsulation efficiency (EE%) and drug loading capacity (LC%) were about 98% and 49%, respectively. The release of 5-FU from NPs showed pH-dependent manner, with an initial rapid release (within 6 h) followed by a sustained release for 96 h at pH 5.4. interestingly, the cumulative release of 5-FU was about 3.9% in neutral medium over 96 h. the results supported the Intelligent release of cargoes from theranostic nanoparticles. At the final step, targeted nanoparticles were successfully synthesized with a final size diameter of 78 nm and negative surface charge. In vitro results demonstrated higher cytotoxicity and anti-cancer property of targeted nanoparticles against EpCAM-positive HT-29 cells as compared to the EpCAM-negative CHO cells, confirming the effectiveness of aptamer as a targeting ligand.
Conclusion: These findings suggest that application of the targeted formulation can be considered as a promising theranostic platform for EpCAM-positive CRC cells. However, further experiments are required before it can be practiced in the clinic.