ABSTRACT
BACKGROUND: Transfection is the most important beginning component of research about gene function. It is a problem to find a transfection agent with high efficiency and safety. Nanosized materials have high surface activity, are easy to be modified and easier to pass the biomembrane. Researchers are studying how to use nanosized materials as a transfection agent.OBJECTIVE: To study the transfection efficiency of different basic polymers with different molecular mass and degree of substitute, and to find the optimized transfection agent.DESIGN: Controlled study.SETTING: Institute of Genetic Engineering, Southern Medical University.METHODS: This study was performed in the Institute of Genetic Engineering, Southern Medical University from March 2006 to June 2007. Using the lipofectamine reagent as the positive control, we transfected siRNA (0.2 nmol/L), FITC-labeling targeting bcl-2, by nine nanometers (polylactic acid-polyglycolic acid, chitosan-poly-caprolactone, polyethyleneimin-macrogol) into leukemic cell K562 cultured without serum. Six hours post-transfection, 20% FBS serum was added. The cell proliferation was measured at 24, 48 and 72 hours by using the MTT method. After transfecting for 48 hours, the cells were collected to detect transfection ratio by using fluorescent microscopy, apoptosis ratio and expression of K562 and bcl-2 protein by flow cytometer (FCM). RESULTS: ① Fluorescence microscope detection showed there were significant differences of transfection efficiency between different materials (P < 0.05). Moreover there were statistical differences between different degrees of substitute, although they were the same material (P < 0.05). ② MTT method indicated the cell proliferation ratio was positively related to transfection ratio. ③ Flow cytometry results showed the suppression of expression of targeting gene and apoptosis ratio were positive correlated with transfection ratio. CONCLUSION:The nanometer poly-ethylene glycol combined with poly-ethylene imine (PEG-PEI), whose molecular mass is 1 800/2 000 and degree of substitute is 29%, has a high efficiency and low toxicity.