title: Octreotide Functionalized Nano-Contrast Agent for Targeted Magnetic Resonance Imaging.
abstract: Reversible addition-fragmentation chain transfer (RAFT) polymerization has been employed to synthesize branched block copolymer nanoparticles possessing 1,4,7,10-tetraazacyclododecane-N,N,'N,″N,‴-tetraacetic acid (DO3A) macrocycles within their cores and octreotide (somatostatin mimic) cyclic peptides at their periphery. These polymeric nanoparticles have been chelated with Gd3+and applied as magnetic resonance imaging (MRI) nanocontrast agents. This nanoparticle system has an r1relaxivity of 8.3 mM-1s-1, which is 3 times the r1of commercial gadolinium-based contrast agents (GBCAs). The in vitro targeted binding efficiency of these nanoparticles shows 5 times greater affinity to somatostatin receptor type 2 (SSTR2) with Ki= 77 pM (compared to somatostatin with Ki= 0.385 nM). We have also evaluated the tumor targeting molecular imaging ability of these branched copolymer nanoparticle in vivo using nude/NCr mice bearing AR42J rat pancreatic tumor (SSTR2 positive) and A549 human lung carcinoma tumor (SSTR2 negative) xenografts.
authors.affiliation: Institute of Chemical and Engineering Sciences , Agency for Science, Technology and Research (A* Star), 1 Pesek Road, Jurong Island, Singapore , 627833.
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Jackson
authors.affiliation: Singapore Bioimaging Consortium , Agency for Science, Technology and Research (A* Star), 11 Biopolis Way, Helios, Singapore , 138667.
authors.forename: Prashant
authors.initials: P
authors.lastname: Chandrasekharan
authors.affiliation: Singapore Bioimaging Consortium , Agency for Science, Technology and Research (A* Star), 11 Biopolis Way, Helios, Singapore , 138667.
authors.forename: Boominathan
authors.initials: B
authors.lastname: Ramasamy
authors.affiliation: Singapore Bioimaging Consortium , Agency for Science, Technology and Research (A* Star), 11 Biopolis Way, Helios, Singapore , 138667.|Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore , Singapore , 117456.
authors.forename: Julian
authors.initials: J
authors.lastname: Goggi
authors.affiliation: Singapore Bioimaging Consortium , Agency for Science, Technology and Research (A* Star), 11 Biopolis Way, Helios, Singapore , 138667.|Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore , Singapore , 117456.|Clinical Imaging Research Centre, Yong Loo Lin School of Medicine, National University of Singapore , Singapore , 117599.
authors.forename: Kai-Hsiang
authors.initials: KH
authors.lastname: Chuang
authors.affiliation: Institute of Chemical and Engineering Sciences , Agency for Science, Technology and Research (A* Star), 1 Pesek Road, Jurong Island, Singapore , 627833.
authors.forename: Tao
authors.initials: T
authors.lastname: He
authors.affiliation: Singapore Bioimaging Consortium , Agency for Science, Technology and Research (A* Star), 11 Biopolis Way, Helios, Singapore , 138667.|Clinical Imaging Research Centre, Yong Loo Lin School of Medicine, National University of Singapore , Singapore , 117599.
authors.forename: Edward G
authors.initials: EG
authors.lastname: Robins
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000378:metabolism*; D005260:Female; D005682:Gadolinium / Q000378:metabolism*; D005765:Gastrointestinal Agents / Q000378:metabolism; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D057054:Molecular Imaging / Q000379:methods*; D053758:Nanoparticles / Q000008:administration & dosage* / Q000737:chemistry; D015282:Octreotide / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000737:chemistry; D058105:Polymerization; D011108:Polymers / Q000737:chemistry*; D051381:Rats; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D003287:Contrast Media; D005765:Gastrointestinal Agents; D011108:Polymers; D011092:Polyethylene Glycols; D005682:Gadolinium; D015282:Octreotide