Research Article Sustained Release and Cytotoxicity Evaluation of Carbon Nanotube-Mediated Drug Delivery System for Betulinic Acid Julia M. Tan, 1 Govindarajan Karthivashan, 2 Palanisamy Arulselvan, 2 Sharida Fakurazi, 2,3 and Mohd Zobir Hussein 1 1 Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia 2 Laboratory of Vaccine and Immunotherapeutics, Institute of Bioscience (IBS), Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia 3 Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia Correspondence should be addressed to Mohd Zobir Hussein; mzobir@upm.edu.my Received 11 July 2014; Accepted 4 September 2014; Published 15 September 2014 Academic Editor: Krasimir Vasilev Copyright © 2014 Julia M. Tan et al. his 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. Carbon nanotubes (CNTs) have been widely utilized as a novel drug carrier with promising future applications in biomedical therapies due to their distinct characteristics. In the present work, carboxylic acid-functionalized single-walled carbon nanotubes (f-SWCNTs) were used as the starting material to react with anticancer drug, BA to produce f-SWCNTs-BA conjugate via - stacking interaction. he conjugate was extensively characterized for drug loading capacity, physicochemical properties, surface morphology, drug releasing characteristics, and cytotoxicity evaluation. he results indicated that the drug loading capacity was determined to be around 20 wt% and this value has been veriied by thermogravimetric analysis. he binding of BA onto the surface of f-SWCNTs was conirmed by FTIR and Raman spectroscopies. Powder XRD analysis showed that the structure of the conjugate was unafected by the loading of BA. he developed conjugate was found to release the drug in a controlled manner with a prolonged release property. According to the preliminary in vitro cytotoxicity studies, the conjugate was not toxic in a standard ibroblast cell line, and anticancer activity was signiicantly higher in A549 than HepG2 cell line. his study suggests that f-SWCNTs could be developed as an eicient drug carrier to conjugate drugs for pharmaceutical applications in cancer chemotherapies. 1. Introduction he revolutionary development of drug delivery technology has become one of the most prominent areas in biomedical science, contributing to a profound beneicial impact on human healthcare. his interdisciplinary technology can be deined as a method or process of delivering drugs and biomolecules to the targeted site of the cell for a speciic period of time (sustained release function) with reduced side efect. he current methods of conventional drugs administered via liquids or tablets are generally less ei- cient and sufered from poor biodistribution, low solubility, long-term toxicity, and limited drug eicacy due to partial biodegradation, swelling, and erosion [1]. his has caused the pharmaceutical industry to develop novel drug delivery systems using a wide range of biocompatible drug carriers with the aim to improve therapeutic eicacy and reduced tox- icity. In meeting this demand, various forms of eicient and biocompatible drug delivery systems have been developed extensively and can be generally classiied into four major categories: nanomaterials [2–4], viral carriers [5, 6], organic cationic compounds [7, 8], and recombinant proteins [9, 10]. In the recent years, nanomaterials such as carbon nan- otubes (CNTs) have been receiving considerable amount of attention as a new nonviral carrier alternative [11–13] compared to viral and cationic carrier. hese allotropes of carbons are extensively studied and investigated as novel drug delivery vehicles due to their good biocompatibility, ultrahigh surface area, good mechanical strength yet ultralight weight, low cytotoxicity, and excellent chemical and thermal stability. Hindawi Publishing Corporation Journal of Nanomaterials Volume 2014, Article ID 862148, 11 pages http://dx.doi.org/10.1155/2014/862148