Book of Abstracts - Ruhr-Universität Bochum

OP-37
ISBOMC `10 5.7 – 9.7. 2010 Ruhr-Universität Bochum
Fluorescent Conjugates Between Dinuclear Rhenium(I) Complexes and Peptide
Nucleic Acids (PNA) for Cell imaging and DNA Targeting
Emanuela Licandro, *a S. Maiorana, a C. Baldoli, b G. Prencipe, a E. Ferri, a D. Donghi, c M. Panigati, c
G. D’Alfonso, c and L. D’Alfonso d
a Dipartimento di Chimica Organica e Industriale, Università degli Studi di Milano, Via Venezian 21,
I-20133, Milano, Italy. b Istituto di Scienze e Tecnologie Molecolari, C.N.R., Via C. Golgi 19, I-20133
Milano, Italy. c Dipartimento di Chimica Inorganica, Metallorganica e Analitica, Università degli
Studi di Milano, Via Venezian 21, I- 20133, Milano, Italy. d Dipartimento di Fisica, Università di
Milano-Bicocca, P.za Scienze 6, I-20126 Milan. Italyo.
E-mail: emanuela.licandro@unimi.it
Peptide nucleic acids (PNA) are structural analogues of DNA, with pseudo-peptide backbone based on
N-(2-aminoethyl)glycine, which show high binding affinity and specificity for the complementary
DNA and RNA. 1 The conjugation of organometallic complexes to biomolecules finds applications
both in diagnostic and therapeutic fields. The incorporation of Re(I) complexes into PNA, can offer a
double advantage, due both to its radiochemical and photo-emitting properties.
In this communication we describe the set up of the synthesis of new PNA-rhenium organometallic
bioconjugates as luminescent compounds for DNA targeting. In particular, we utilized two novel
rhenium complexes, namely [Re2(CO)6(�-Cl)2(�-4-COOH-pyridazine)] and Re2(CO)6(�-Cl)2(�-4-
(CH2)3COOH-pyridazine)], belonging to a recently developed family of dimeric luminescent
rhenium(I) complexes, 2 which were conjugated with the tymine PNA monomer and decamer. The
second complex was prepared in order to check the influence of the n-propyl chain spacer on the
lifetime and quantum yields of the emission of the PNA-rhenium bioconjugate. The most fluorescent
Re-PNA conjugate also showed two photon absorption properties as assessed by “in cell” experiments,
that revealed that it permeates the cell membrane, staining both the cytoplasm and the nucleus.
Although more detailed experiments are needed, in order to establish the kinetics of the process and to
set a lower limit to the sample concentration to be used, these preliminary results indicate that the Re-
PNA conjugate is viable as a fluorophore for cell imaging.
References
1. Peptide Nucleic Acids; 2nd Ed.; P. E. Nielsen, Ed.; Horizon Bioscience: Norfolk, UK, 2004.
2. D. Donghi, G. D’Alfonso, M. Mauro, M. Panigati, P. Mercandelli, A. Sironi, P. Mussini, L.
D’Alfonso, Inorg. Chem. 2008, 47, 4243-4255.
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