Special Issue: "Dendritic-Sensors"

Guest Editor
Prof. Dr. Brian D. Wagner
3M Canada National Teaching Fellow
Department of Chemistry
University of Prince Edward Island
Charlottetown, PE C1A 4P3
E-mail: bwagner@upei.ca; Tel. 902-628-4351; Fax 902-566-0632
http://www.upei.ca/~chem/wagner.html

Deadline for Paper submission: 30 June 2009
Related Special Issue: "Dendrimers" - Molecules

Planned Papers

Title: FRET Processes in Photoresponsive Dendrimers: A Review of Theory
Authors: David L. Andrews, David S. Bradshaw, Robert D. Jenkins and Justo Rodriguez
School of Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom. Tel: +44 1603 5929014/592707. Fax: +44 1603 592003; E-mail: d.l.andrews@uea.ac.uk
Abstract: to be added

Title: Vibrational and Electronic Spectra of Porphyrin-Cored 2,2-Bis(methylol)propionic Acid Dendrimers
Authors: Boris Minaev, Hans Agren, Theoretical Chemistry, Royal Institute of Technology, AlbaNova, S-106 91 Stockholm, Sweden.
Robert Vestberg, Andreas NystrÄom, Fibre and Polymer Technology, Royal Institute of Technology, Teknikringen 56-58, S-100 44 Stockholm, Sweden.
Mikael Lindgren *, Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
* Corresponding Author: Mikael Lindgren, Email: mikael.lindgren@phys.ntnu.no, Phone: +47 73593414 Fax: +47 73597710
Abstract: Dendron-coated free-base tetraphenylporphin and zinc-tetraphenylporphyrin (TPPH2 and TP-PZn) were studied in comparison with simple porphyrins (H2P, ZnP) by theoretical simulation of their infrared, Raman, electronic absorption spectra as well as °uorescense emission. Dendrons were divergently grown using both TPPH2 and TPPZn together with the acetonide-2,2-bis(methoxy)propanoic anhydride. This synthesis provided controlled porphyrin-cored dendrimers up to ¯fth generation with increased hydrolytic stability with increased size of dendrimer. IR, Raman absorption and °uorescence spectra of the dendrimers were detected and interpreted along with time-resolved measurements of the °uorescence emission. The 0-1 emission band of the dendron substituted TPPZn experiences a "heavy substitution"-e®ect. The 0-1 vibronic emission signal was associated with a longer decay time (approx. 7 - 8 ns) than the 0-0 emission (approx. 1 - 1.5 ns). The former contributed with more relative emission yield for larger dendron substituents, in agreement with the appearance of steady state emission spectra showing increased contribution from the 0-1 vibronic °uorescence band at 650 nm. No such substitution e®ect was observed in the electronic or vibrational spectra of the substituted free-base variant, TPPH2. Vibrational spectra of the parent porphyrins (H2P, ZnP, TPPH2 and TPPZn) were calculated by density functional theory (DFT) using the B3LYP/6-31G** approximation and a detailed analysis of the most active vibrational modes was made based on both literature and our own experimetnal data. Based on the results of theoretical calculations the wide vibronic bands in the visible region were assigned. The vibronic structure also gave a qualitative interpretation of bands in the electronic absorptionspectra as well as in °uorescence emission depending on the size of dendrimer substitution. From the absorption and °uorescence data studied by time-dependent DFT we come to the conclusion that the TPPZn-cored dendrimers indicate strong vibronic interaction and increased Jahn-Teller distortion of the prophyrin core at higher dendrimer generations. Speci¯cally, this leads to the entirely di®erent behaviour of the emission spectra upon substitution of the TPPH2 and TPPZn variants, which was also observed experimentally. Since TPPH2 is originally of lower symmetry the speci¯c distortion upon dendron substitution is not expected to the same extent, which also is in agreement with the experimental results.

Title: Human NK cell up-regulation of CD69, interferon-gamma secretion and cytotoxic activity by plasmacytoid dendritic cells is regulated through overlapping but different pathways
Authors: Adel Benlahrech, Heather Donaghy, George Rozis, Martin Goodier, Dhayanethie Perumal, Linda Klavinskis, Frances Gotch and
Steven Patterson
Department of Immunology, Division of Investigative Science, Imperial College School of Medicine, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH; Tel 0208 746 5934, Fax 0208 746 5997
E-mail: s.patterson@imperial.ac.uk;

Title: Fluorescence Studies of the Host Properties of PAMAM Dendrimers
Author: Brian D. Wagner
PhD, Professor, 3M Canada National Teaching Fellow, Department of Chemistry, University of Prince Edward Island, Charlottetown, PE C1A 4P3; E-mail: bwagner@upei.ca, phone: 902-628-4351, fax: 902-566-0632
Abstract: to be added soon

Title: An Electrochemical DNA Biosensor Developed on a Nanocomposite Platform of Gold and Poly(propylene imine) Dendrimer
Author: Omotayo A. Arotiba, Joseph Owino, Nicolette Hendricks, Tesfaye T. Waryo, Nazeem Jahed, Priscilla G.L. Baker and Emmanuel I. Iwuoha *
SensorLab, Department of Chemistry, University of the Western Cape, Bellville, Cape Town 7535, South Africa; * Corresponding author: eiwuoha@uwc.ac.za.
Abstract: A novel electrochemical DNA nanobiosensor was prepared by the immobilisation of a 20mer thiolated probe DNA (SH-5'-AAGCGGAGGATTGACGACTA-3¢) on a gold nanoparticle (AuNP)-doped generation 4 (G4) poly(propylene imine) dendrimer (PPI) electro-deposited on a glassy carbon electrode (GCE). Field emission scanning electron microscopy results confirmed the co-deposition of PPI which was linked to the carbon electrode surface by C-N covalent bonds and AuNP ca 60 nm. The DNA probe was effectively wired onto the GCE/PPI-AuNP via Au-S linkage and electrostatic interactions. Voltammetric interrogations showed that the GCE/PPI-AuNP electrode system was conducting and exhibited reversible electrochemistry ( = 235 mV) in phosphate buffer solution (PBS) pH 7.2 due to the PPI component. The redox chemistry of PPI was pH dependent and involved a two electron, one proton process as interpreted from a 28 mV/pH value obtained from pH studies. The charge transfer resistance (Rct) from the electrochemical impedance spectroscopy (EIS) profiles of GCE/PPI-AuNP monitored with ferrocyanide/ferricyanide (Fc) redox probe, decreased by 81% compared to bare GCE. The conductivity (in PBS) and reduced Rct (in Fc) values confirmed PPI-AuNP as a suitable electron transfer mediator for voltammetric and impedimetric DNA biosensor. The nanobiosensor responses to target DNA which gave a dynamic linear range of 0.01 - 5 nM in PBS was based on the changes in Rct values using Fc redox probe.
Keywords: Poly(propylene imine) dendrimer, gold nanoparticle, electrochemical impedance spectroscopy, electrochemical DNA biosensor, DNA.

Keywords
Dendrimers, Dendritic Cells, Dendritic Fluorescent Sensors, Biosensors

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Sensors Journal Special Issues

MDPI - Matthias Burkhalter - 23 September 2008