1. INTRODUCTION Dual functionalized nanoparticles have gained a widespread application in the diagnosis and therapy of several diseases. Surface nanoparticles functionalization with: (i) biomolecules as monoclonal antibodies and (ii) radiolabel compounds as 99m Tc offers an exciting new paradigm change for real medicine due to the possibility of combination treatment and diagnostic, known as theragnosis.
2. OBJECTIVE. The purpose of our work is to study the suface functionalization process of taxol-loaded PLGA nanoparticles by radiolabelling with 99m Tc and by bioconjugation process with a MAb specific for HER-2+ breast cancer cells.
3. MATERIALS AND METHODS PLGA nanoparticles were prepared using the nanoprecipitation method. Nanoparticles were surface modified with (i) a MAb against HER2+ cancer cells using the carbodiimide strategy. The conjugated amount of MAb was determined by an HPLC-SEC method and (ii) Different amounts of stannous fluoride in aqueous solution were added to a suspension of 5mg of nanoparticles. Then, ≈74MBq (2 mCi) of 99mTc was added and incubated for 10 min. 99mTc-NPs suspensions were analyzed by TLC with silica gel strips.
For citotoxicity assay, SK-BR-3 cell line was seeded in 96-well plates and the treatment was assayed after the application of decreasing concentrations in a 1:3 fixed ratio to exponential phase growing cells. Proliferation was determined by crystal violet assay after 96 hours. Cytotoxicity was measured by absorbance at 595 nm using a microplate reader (BIORAD iMark™ Microplate Reader); then, the IC50 was estimated using GraphPad Prism 4 software.
4. RESULTS AND DISCUSSION. We obtained PLGA nanoparticles 190 nm in diameter with a zeta potential around -20 mV. After MAb-conjugation particles diameter increases slightly up to 250-300 nm. ZP values were nearly neutrality which indicates the presence of MAb on particle surface. Antibody conjugation efficiency was around 90%. In addition, using 1 μg of SnF2 as a reducing agent, PLGA nanoparticles were labelled with 99mTc with a yield ≥ 90%. Cytotoxicity assay, demonstrated a superior antitumoral activity of encapsulated vs. free taxol with improved IC50 values against SK-BR-3 cells.
5. CONCLUSIONS Results obtained, indicated that nanoparticles are suitable as future platform for in vivo therganosis of breast cancer.
Targeted drug delivery and nanocarriers , Nanomedicine for cancer diagnosis & therapy
