Journal of Alloys and Compounds 502 (2010) 439–444 Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jallcom Synthesis of protoporphyrin coated superparamagnetic iron oxide nanoparticles via dopamine anchor Nurufe Kemikli a , Huseyin Kavas b , Sinan Kazan c , Abdulhadi Baykal a , Ramazan Ozturk a,∗ a Department of Chemistry, Faculty of Arts and Science, Fatih University, Istanbul 34500, Turkey b Department of Physics, Faculty of Arts and Science, Fatih University, Istanbul 34500, Turkey c Department of Physics, Faculty of Science, Gebze Institute of Technology, Cayirova-Gebze, Kocaeli 41400, Turkey article info Article history: Received 12 March 2010 Received in revised form 20 April 2010 Accepted 25 April 2010 Available online 5 May 2010 Keywords: Protoporphyrin IX Dopamine Fe3O4 nanoparticle Magnetism abstract Dopamine conjugated protoporphyrin, PPD, was prepared by the coupling reaction of protoporphyrin IX and dopamine in the presence of dicyclohexylcarbodiimide (DCC) and N-hydroxysuccinimide (NHS) in DMF. The crude product was washed with ethanol–cyclohexane (1:1) mixture to remove dicyclohexy- lurea (DCU). Previously prepared Fe 3 O 4 nanoparticles were coated with PPD (sub-7 nm monosize) by sonication in the methanol. The porphyrin coated Fe 3 O 4 nanoparticles, PPDNP were separated by perma- nent magnet. The microstructure and magnetic properties of magnetic nanoparticles were characterized by XRD, TEM, FT-IR, and VSM. It is found that the nanoparticles have high crystallinity with distinct lat- tices and the magnetic measurements reveal their well-defined superparamagnetic behavior at room temperature. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Protoporphyrin (PpIX) is the most reactive molecule among the porphyrinic photosensitizers towards to conjugate formation which is commonly used in photodynamic therapy (PDT) [1]. An approach to PDT of cancer, in preclinical and clinical studies, is based on the endogenous accumulation of protoporphyrin IX used as a precursor photosensitizer. Among them, protoporphyrin IX (which is a natural precursor of heme) as photosensitizer, binds to Fhit protein (fragile histidine triad) and its mutants in the active site in vitro inhibits the enzymatic activity of Fhit [2]. Kammerer et al. [3] have characterized the rescue response of human PC-3 prostate cancer cells exposed in vitro to sublethal PDT after 5-aminolevulinic acid-induced protoporphyrin IX sensitization at the transcriptome level using Affymetrix HG U133 Plus 2.0 oligonucleotide microar- rays. To construct a molecular porphyrinic conjugate with the SPION (superparamagnetic iron nanoparticles) for potential appli- cations in hyperthermia (HT) and PDT, protoporphyrin IX and magnetite (paramagnetic Fe 3 O 4 ) are indispensable building blocks [4,5]. The enhancement of the accumulation of porphyrin pho- tosynthesizers against biological substrates can be achieved by the conjugate formation with biomolecules (e.g. amino acids, pro- teins) [6,7]. For this purpose, ene-diol containing compounds (e.g. dopamine, catechol) are commonly in nature, playing important ∗ Corresponding author. Tel.: +90 212 866 3300/2072; fax: +90 212 866 3402. E-mail address: rozturk@fatih.edu.tr (R. Ozturk). key roles in many biological reactions and in medical treatment and also results in altered optical properties of nanoparticles [8]. It is known that catechol acts as a chelating agent, forming tight bonds with iron oxides by converting the under-coordinated cationic iron surface sites to a bulk-like lattice structure [9]. Also, dopamine has the ability to replace the original capping ligand, oleylamine, on the Fe 3 O 4 NPs surface and act as a robust anchor on the surface of Fe 3 O 4 NPs. Moreover, the exceptional thermal stability of the dopamine- based anchor on the iron oxide surfaces satisfies the requirement of HT (hyperthermia) [10]. Xu et al. [11] used dopamine (DA) as a stable anchor to present functional molecules on the surface of iron oxide nanostructures. Transition metal oxides have been of scientific and technological interest for many decades due to their interesting optical, mag- netic, electrical and catalytical properties. Among these, magnetite (Fe 3 O 4 ) is a common magnetic iron oxide that has a cubic inverse spinel structure [12–15]. The use of surface functionalized aqueous suspension of magnetite nanoparticles in clinical medicine has also intensified [16–18]. Magnetic nanoparticles are also used extensively in the field of biomagnetics for a broad range of applications, such as drug delivery [11,19–20], cell labeling and sorting [21], magnetic reso- nance imaging, sensing [22,23] as well as therapeutic applications [24] such as an AC magnetic field-assisted cancer therapy, i.e. hyperthermia, PDT [25]. Qu et al. [26] synthesized Fe 3 O 4 –chitosan nanoparticles used for hyperthermia (in this study glutaraldehyde was used to crosslink the chitosan). Gu et al. [9] reported the synthesis and cellular uptake of the conjugate of porphyrin and 0925-8388/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2010.04.192