JANA ET AL . VOL. XXX ’ NO. XX ’ 000–000 ’ XXXX www.acsnano.org A C XXXX American Chemical Society Perylene-Derived Single-Component Organic Nanoparticles with Tunable Emission: Efficient Anticancer Drug Carriers with Real-Time Monitoring of Drug Release Avijit Jana, † Kim Truc Nguyen, † Xin Li, ‡ Pengcheng Zhu, § Nguan Soon Tan, § Hans A ˚ gren, ‡, * and Yanli Zhao †,^, * † Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, ‡ Department of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology, Stockholm, Sweden SE-10691, § School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, and ^ School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 I n order to enhance therapeutic efficacy, the protection of drug molecules from leaching, degradation, or interaction with the biological environment before reaching the target sites is crucial for drug delivery systems (DDSs). 1 In recent years, many so- phisticated stimuli-responsive DDSs based on metallic nanoparticles, 26 ceramic nano- particles, 711 polymers, 12,13 dendrimers, 1416 liposomes, 1719 and micelles 20,21 have been developed. Though these nanocarriers have their own advantages such as easy synthe- sis, tunable particle size, and low cytotoxi- city, they often suffer from several serious limitations including (i) premature release or leaching of loaded drug molecules, (ii) imprecise control of the drug release over an extended period of time, and (iii) low drug loading efficacy (e.g., 2.5% for Au nano- particles, 3 0.9% for Fe 3 O 4 nanoparticles, 4 9.9% for hollow mesoporous silica nano- particles, 11 and 6.0% of doxorubicin for mesoporous silica nanoparticles 22 ), result- ing in the utilization of a large amount of unwanted carriers. Among various externally regulated sti- muli, light is one of the best agents for triggering the release of drugs from the above-mentioned DDSs since the activation processes by light are rapid and clean and allow for low invasiveness as far as biological systems are concerned. Thus, light-induced * Address correspondence to zhaoyanli@ntu.edu.sg; agren@theochem.kth.se. Received for review February 23, 2014 and accepted May 13, 2014. Published online 10.1021/nn501073x ABSTRACT An organic nanoparticle-based drug delivery system with high drug loading efficacy (∼79 wt %) was developed using a perylene-derived photoremovable protecting group, namely, perylene- 3,4,9,10-tetrayltetramethanol (Pe(OH) 4 ). The anticancer drug chlorambucil was protected by coupling with Pe(OH) 4 to form photocaged nanoparticles (Pe(Cbl) 4 ). The photorelease mechanism of chlorambucil from the Pe(Cbl) 4 conjugate was investigated experimentally by high-resolution mass spectrometry and theoretically by density functional theory calculations. The Pe(Cbl) 4 nanoparticles perform four important roles: (i) a nanocarrier for drug delivery, (ii) a phototrigger for drug release, (iii) a fluorescent chromophore for cell imaging, and (iv) a photoswitchable fluorophore for real-time monitoring of drug release. Tunable emission of the perylene-derived nanoparticles was demonstrated by comparing the emission properties of the Pe(OH) 4 and Pe(Cbl) 4 nanoparticles with perylene-3-ylmethanol. These nanoparticles were subsequently employed in cell imaging for investigating their intracellular localization. Furthermore, the in vivo toxicity of the Pe(OH) 4 nanoparticles was investigated using the mouse model. Histological tissue analysis of five major organs, i.e., heart, kidney, spleen, liver, and lung, indicates that the nanoparticles did not show any obvious damage to these major organs under the experimental conditions. The current research presents a successful example of integrating multiple functions into single-component organic nanoparticles for drug delivery. KEYWORDS: chlorambucil . drug delivery . organic nanoparticles . photoremovable protecting group . tunable emission ARTICLE