Dual-aptamer-based delivery vehicle of doxorubicin to both PSMA (þ) and PSMA () prostate cancers Kyoungin Min a,1 , Hunho Jo a, 1 , Kyungmi Song a , Minseon Cho b , Yang-Sook Chun c , Sangyong Jon d , Won Jong Kim a , Changill Ban a, * a Department of Chemistry, Pohang University of Science and Technology, San31, Hyoja-dong, Pohang, Gyungbuk, 790-784, South Korea b Department of Mechanical Engineering, Department of Materials, University of California e Santa Barbara, Santa Barbara, CA 93106, USA c Department of Physiology, Seoul National University College of Medicine, 28 Yeongeon-dong, Jongno-gu, Seoul,110-799, South Korea d Cell Dynamics Research Center, School of Life Sciences, 261 Cheomdangwagi-ro, Gwangju 500-712, North Korea article info Article history: Received 5 October 2010 Accepted 14 November 2010 Available online 13 December 2010 Keywords: Drug delivery PSMA (þ) and PSMA () prostate cancer cells A10 RNA aptamer DUP-1 peptide aptamer Differential pulse voltammetry Superparamagnetic iron oxide nanoparticle abstract We have designed a dual-aptamer complex specific to both prostate-specific membrane antigens (PSMA) (þ) and () prostate cancer cells. In the complex, an A10 RNA aptamer targeting PSMA (þ) cells and a DUP-1 peptide aptamer specific to PSMA () cells were conjugated through streptavidin. Doxorubicin- loaded onto the stem region of the A10 aptamer was delivered not only to PSMA (þ) cells but to PSMA () cells, and eventually induced apoptosis in both types of prostate cancer cells. Cell death was monitored by measuring guanine concentration in cells using differential pulse voltammetry (DPV), a simple and rapid electrochemical method, and was further confirmed by directly observing cell morphologies cultured on the transparent indium tin oxide (ITO) glass electrode and checking their viabilities using a trypan blue assay. To investigate the in vivo application of the dual-aptamer system, both A10 and DUP-1 aptamers were immobilized on the surface of thermally cross-linked super- paramagnetic iron oxide nanoparticles (TCL-SPION). Selective cell uptakes and effective drug delivery action of these probes were verified by Prussian blue staining and trypan blue staining, respectively. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Diverse drug delivery systems related to cancer therapy have been gradually developed [1,2]. The delivery systems aim to achieve efficient transportation, resulting in maximizing drug effects and reducing side effects. It is well-known that regulations such as the release, adsorption, and site-specific targeting of drugs are crucial factors in these systems. In particular, drug delivery to a specific target has received great attention, since it is the key factor in the drug’s effect on the body [3,4]. Several ligands, like the antibody and aptamer, are actively used for targeting drug delivery systems. Among them, the aptamer has been issued as a powerful biological ligand because of its high selectivity and binding strength to the target molecules [5e7]. Aptamers are oligonucleic acid or peptide molecules which can attach to a specific target molecule. Nucleic acid aptamers are small in size and have good stability in harsh conditions. Peptide aptamers are proteins designed to interact with target molecules. They consist of a variable loop bound at both ends to a protein scaffold. The aptamer has some advantages over an antibody, such as chemical synthesis in vitro, economical produc- tion, easy modification, and high stability in various physical and chemical environments. Delivery vehicles to a target are also important in drug delivery systems and many delivery substances have been studied widely [8e10]. In particular, nanoparticles have been issued as one of the best media of drug delivery [11,12]. Among these, superparamagnetic iron oxide nanoparticles (SPION) are actively used as magnetic resonance (MR) contrast agents and magnetic field-guided drug delivery vehicles for the treatment of many diseases [13e17]. Ther- mally cross-linked SPION (TCL-SPION), used for the purpose of in vivo therapy, has some advantages, such as good dispersibility in a physi- ological medium, biocompatibility, and an anti-biofouling property that prevents the adsorption of plasma proteins or cells onto their surface [18]. Thus, it is possible to apply TCL-SPION, conjugated with targeting ligands, in many drug delivery systems [19]. Prostate cancer is directly related to male death [20,21], and is represented by two types of cell lines (PSMA (þ) and PSMA ()) based on the expression of PSMA, a type II integral membrane * Corresponding author. Tel.: þ82 54 279 2127; fax: þ82 54 279 3399. E-mail address: ciban@postech.ac.kr (C. Ban). 1 These authors contributed equally to this work. Contents lists available at ScienceDirect Biomaterials journal homepage: www.elsevier.com/locate/biomaterials 0142-9612/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.biomaterials.2010.11.035 Biomaterials 32 (2011) 2124e2132