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Journal of Drug Delivery
Volume 2012, Article ID 218940, 12 pages
Research Article

Intracellular Delivery of siRNA by Polycationic Superparamagnetic Nanoparticles

1Department of Chemistry, University of Puerto Rico at Humacao, Humacao 00791, Puerto Rico
2Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge University, MA 02139, USA
3Department of Biology, University of Puerto Rico at Río Piedras, San Juan 00931, Puerto Rico

Received 15 February 2012; Revised 11 July 2012; Accepted 14 July 2012

Academic Editor: Indu Pal Kaur

Copyright © 2012 Betzaida Castillo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The siRNA transfection efficiency of nanoparticles (NPs), composed of a superparamagnetic iron oxide core modified with polycationic polymers (poly(hexamethylene biguanide) or branched polyethyleneimine), were studied in CHO-K1 and HeLa cell lines. Both NPs demonstrated to be good siRNA transfection vehicles, but unmodified branched polyethyleneimine (25 kD) was superior on both cell lines. However, application of an external magnetic field during transfection (magnetofection) increased the efficiency of the superparamagnetic NPs. Furthermore, our results reveal that these NPs are less toxic towards CHO-K1 cell lines than the unmodified polycationic-branched polyethyleneimine (PEI). In general, the external magnetic field did not alter the cell’s viability nor it disrupted the cell membranes, except for the poly(hexamethylene biguanide)-modified NP, where it was observed that in CHO-K1 cells application of the external magnetic field promoted membrane damage. This paper presents new polycationic superparamagnetic NPs as promising transfection vehicles for siRNA and demonstrates the advantages of magnetofection.