Polymeric nanoparticles for therapy and imaging † Wenjie He a , Hossein Hosseinkhani a,b *, Reza Mohammadinejad a , Ziba Roveimiab a , Dueng-Yuan Hueng c , Keng-Liang Ou b and Abraham J. Domb d Polymeric nanoparticles and their applications have been studied over the long period. Polymeric nanoparticles have been shown to be promising carriers for drug delivery because of their potential in encapsulating drugs hence protecting them from excretion and metabolism. Different polymers have been used, and different strategies such as surface modification have been carried out to increase the retention time of nanoparticles and to increase therapeutic benefit while minimizing side effects. Here, we review aspects of polymeric nanoparticles and their application in magnetic resonance imaging technology, disease therapy, drug delivery systems, and gene transfer. Copyright © 2014 John Wiley & Sons, Ltd. Keywords: polymeric nanoparticles; cell targeting; DDS; MRI; cancer therapy; bioimaging INTRODUCTION Biodegradable nanoparticles (NPs) have gained much interest for imaging, cancer treatment, medical tools, bone treatment, drug de- livery, diagnostic tests, and drug development. [1–10] Because NPs have the ability to enter, translocate within, and damage living or- ganism, they can penetrate physiological barrier and travel within the circulatory systems of a host, because of their small size. They can be applied in a wide range of fields, especially in biomedical applications such as drug delivery, gene transfection, cancer treat- ment, and medical imaging. These particles are potentially capable of detecting and preventing disorders very quickly and therefore essentially improving the whole diagnosis, treatment, and pursuit of different diseases. [1–4,6,8,11–14] Rapid development of nanotechnol- ogy will open many gates to a new era of medical technol- ogy. [5,7,9,10,15–20] Our recent results indicate that biodegradable NPs have the capacity to be implemented as tracking agents to transfect stem cells for regenerative medicine therapy. Alternatively, other re- searches indicated that these NPs have many other applications in targeted delivery systems favorable to cancer treatment. [10,21–31] Many studies have been focusing on cancer therapy. These ther- apies are becoming more popular as they are much less harmful when compared with conventional treatment methods. The first point that should be discussed is how to improve the efficiency of the treatment. The application of nanoscale vectors has been proved to bear significant advantages in terms of drug delivery, such as the following: (i) the ability to arrive at the specific sites within the body; (ii) the ability to decrease drug accumulation at untargeted sites in order to minimize severe side effects; and (iii) being harmless and easy exhaustion by the human body. Stimuli-sensitive polymers have been developed in order to maintain normal function for fight- ing diseases, such as different temperature and pH in abnormal tis- sue; some scientists call it as smart polymers. [32] Drug delivery to specific sites within the body is one of the biggest concerns in the field of pharmaceutical and medical sciences. This is because chemotherapy drugs, if not targeted properly, can kill not only tumor cells but also healthy tissues. Some researchers are investigating the possibility to develop a new nanocarrier, such as NPs and micelle. Others are studying super paramagnetic NPs such as iron oxide (SPION), which are widely used as a nanocarrier thanks to their nontoxicity, bio- compatibility, large surface area, and suitable magnetic properties, all of which being favorable for the drug delivery mechanism. Several researches reported using polymer-based nanocapsules in the field of drug delivery. [33] However, the low * Correspondence to: Dr. Hossein Hosseinkhani, Graduate Institute of Biomedical Engineering, National Taiwan University of Science and Technology (Taiwan Tech), Taipei 10607, Taiwan. E-mail: hosseinkhani@mail.ntust.edu.tw † This article is published in Journal of Polymers for Advanced Technologies as a special issue on 12th PAT Conference in Berlin, 2013, edited by Prof. Andreas Lendlein and Prof. Marc Behl, Institute of Biomaterial Science, Helmholtz-Zentrum Geesthacht GmbH, Centre for Materials and Coastal Research, Kantstr. 55, 14513 Teltow, Germany. a W. He, H. Hosseinkhani, R. Mohammadinejad, Z. Roveimiab Graduate Institute of Biomedical Engineering, National Taiwan University of Science and Technology (Taiwan Tech), Taipei 10607, Taiwan b H. Hosseinkhani, K.-L. Ou Nanomedicine Research Center of Taiwan, Research Center for Biomedical devices and Prototyping Production, Research Center for Biomedical Implants and Microsurgery Devices, Graduate Institute of Biomedical Materials and Engineering, College of Oral Medicine, Taipei Medical University, and Department of Dentistry, Taipei Medical University-Shuang-Ho Hospital, Taipei 110, Taiwan c D.-Y. Hueng Department of Biochemistry, National Defense Medical Center, Department of Neurological Surgery, Tri-Service General Hospital, Taipei 114, Taiwan d A. J. Domb Institute of Drug Research, The Center for Nanoscience and Nanotechnology, School of Pharmacy-Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91120, Israel Special issue: Review Received: 04 April 2014, Revised: 05 June 2014, Accepted: 13 July 2014, Published online in Wiley Online Library: 7 October 2014 (wileyonlinelibrary.com) DOI: 10.1002/pat.3381 Polym. Adv. Technol. 2014, 25 1216–1225 Copyright © 2014 John Wiley & Sons, Ltd. 1216