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Special Issue "Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells"

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Biosensors".

Deadline for manuscript submissions: closed (31 December 2009)

Special Issue Editor

Guest Editor
Prof. Dr. Brian D. Wagner

3M Canada National Teaching Fellow, Department of Chemistry, University of Prince Edward, Island Charlottetown, PE C1A 4P3, Canada
Website | E-Mail
Fax: +1 902 566 0632
Interests: chemical sensors; fluorescent sensors; supramolecular systems; self-assembly; host-guest inclusion

Keywords

  • dendrimers
  • dendritic cells
  • dendritic fluorescent sensors
  • biosensors

Published Papers (9 papers)

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Research

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Open AccessArticle Fluorescence-Based Comparative Binding Studies of the Supramolecular Host Properties of PAMAM Dendrimers Using Anilinonaphthalene Sulfonates: Unusual Host-Dependent Fluorescence Titration Behavior
Sensors 2010, 10(4), 4053-4070; doi:10.3390/s100404053
Received: 4 March 2010 / Revised: 31 March 2010 / Accepted: 13 April 2010 / Published: 21 April 2010
Cited by 6 | PDF Full-text (362 KB) | HTML Full-text | XML Full-text
Abstract
This work describes the fluorescence enhancement of the anilinonaphthalene sulfonate probes 1,8-ANS, 2,6-ANS, and 2,6-TNS via complexation with PAMAM dendrimer hosts of Generation 4, 5 and 6. The use of this set of three very closely related probes allows for comparative binding studies,
[...] Read more.
This work describes the fluorescence enhancement of the anilinonaphthalene sulfonate probes 1,8-ANS, 2,6-ANS, and 2,6-TNS via complexation with PAMAM dendrimer hosts of Generation 4, 5 and 6. The use of this set of three very closely related probes allows for comparative binding studies, with specific pairs of probes differing only in shape (1,8-ANS and 2,6-ANS), or in the presence of a methyl substituent (2,6-TNS vs. 2,6-ANS). The fluorescence of all three probes was significantly enhanced upon binding with PAMAM dendrimers, however in all cases except one, a very unusual spike was consistently observed in the host fluorescence titration plots (fluorescence enhancement vs. host concentration) at low dendrimer concentration. This unprecedented fluorescence titration curve shape makes fitting the data to a simple model such as 1:1 or 2:1 host: guest complexation very difficult; thus only qualitative comparisons of the relative binding of the three guests could be made based on host titrations. In the case of G4 and G5 dendrimers, the order of binding strength was qualitatively determined to be 1,8-ANS < 2,6-ANS indicating that the more streamlined 2,6-substituted probes are a better match for the dendrimer cavity shape than the bulkier 1,8-substituted probe. This order of binding strength was also indicated by double fluorometric titration experiments, involving both host and guest titrations. Further double fluorometric titration experiments on 2,6-ANS in G4 dendrimer revealed a host concentration-dependent change in the nature of the host: guest complexation, with multiple guests complexed per host molecule at very low host concentrations, but less than one guest per host at higher concentrations. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
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Open AccessArticle Formation of Zwitterionic Fullerodendron Using a New DBN-Focal Dendron
Sensors 2010, 10(1), 613-624; doi:10.3390/s100100613
Received: 16 November 2009 / Revised: 30 December 2009 / Accepted: 6 January 2009 / Published: 14 January 2010
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Abstract
A new poly(amidoamine) dendron having 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) at the focal point was synthesized. Interestingly, formation of zwitterionic fullerodendrons (λmax = 930 nm for C60 and 795 nm for C70) were observed by Vis-NIR spectroscopy upon the reaction of C
[...] Read more.
A new poly(amidoamine) dendron having 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) at the focal point was synthesized. Interestingly, formation of zwitterionic fullerodendrons (λmax = 930 nm for C60 and 795 nm for C70) were observed by Vis-NIR spectroscopy upon the reaction of C60 or C70 with the DBN-focal dendron. In particular, the C70 anion was effectively stabilized by the site isolation effect of the dendritic wedge. The half-life of fullerodendron 12b having C70 anion at the focal point reaches 7,345 min, which is 20 times longer than that of complex between C60 and pristine DBN. Furthermore, in order to confirm the structure of the zwitterionic complex, fullerodendron 12a was reprecipitated from benzonitrile/1,2,4-trimethylbenzene, and was observed using IR spectroscopy and APPI-MS. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
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Open AccessArticle Metal Ion Enhanced Charge Transfer in a Terpyridine-bis-Pyrene System
Sensors 2009, 9(5), 3604-3626; doi:10.3390/s90503604
Received: 7 April 2009 / Revised: 8 May 2009 / Accepted: 12 May 2009 / Published: 13 May 2009
Cited by 13 | PDF Full-text (488 KB) | HTML Full-text | XML Full-text
Abstract
The synthesis, electrochemical and photophysical properties of a branched molecule 3,5-bis(pyrene-1-yl)-4'-phenyl-2,2':6',2''-terpyridine are reported. Spectroscopy in different solvents reveals that an optical electron transfer from the pyrene donor to the terpyridyl electron acceptor can occur in polar media, as the system displays both charge
[...] Read more.
The synthesis, electrochemical and photophysical properties of a branched molecule 3,5-bis(pyrene-1-yl)-4'-phenyl-2,2':6',2''-terpyridine are reported. Spectroscopy in different solvents reveals that an optical electron transfer from the pyrene donor to the terpyridyl electron acceptor can occur in polar media, as the system displays both charge transfer (CT) absorption and CT emission. Furthermore, the study of the zinc complex as well as the bis-protonated form shows an enhancement of the electron transfer character of the system, by an increase of the acceptor strength. This is accompanied by a large increase of the non-radiative processes. With sub-nanosecond transient absorption spectroscopy, the CT state, consisting of the pyrene radical cation and the terpyridine radical anion, has been detected. At room temperature, the study of the nanosecond transient absorption spectra reveals the formation of a low-lying triplet excited state that we attribute to the pyrene moiety through which the CT state decays. At 77K, the absence of the terpyridine triplet emission also suggests the population of a low-lying triplet state of the pyrene unit. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
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Open AccessArticle Vibration and Fluorescence Spectra of Porphyrin- CoredBis(methylol)-propionic Acid Dendrimers
Sensors 2009, 9(3), 1937-1966; doi:10.3390/s90301937
Received: 21 October 2008 / Revised: 27 February 2009 / Accepted: 16 March 2009 / Published: 16 March 2009
Cited by 16 | PDF Full-text (353 KB) | HTML Full-text | XML Full-text
Abstract
Bis-MPA dendron-coated free-base tetraphenylporphyrin and zinc-tetraphenyl-porphyrin (TPPH2 and TPPZn) were studied in comparison with simple porphyrins (H2P, ZnP) by theoretical simulation of their infrared, Raman and electronic absorption spectra, as well as fluorescense emission. Infrared and fluorescence spectra of the
[...] Read more.
Bis-MPA dendron-coated free-base tetraphenylporphyrin and zinc-tetraphenyl-porphyrin (TPPH2 and TPPZn) were studied in comparison with simple porphyrins (H2P, ZnP) by theoretical simulation of their infrared, Raman and electronic absorption spectra, as well as fluorescense emission. Infrared and fluorescence spectra of the dendrimers were measured and interpreted along with time-resolved measurements of the fluorescence. The 0-1 emission band of the dendron substituted TPPZn was found to experience a "heavy substitution"-effect. The 0-1 vibronic emission signal is 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 fluorescence band at 650 nm. No such substitution effect was observed in the electronic or vibrational spectra of the substituted free-base variant, TPPH2. Vibration 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 vibration modes was made based on both literature and our own experimental 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 absorption spectra as well as in fluorescence emission depending on the size of dendrimer substitution. From the results of time-dependent DFT calculations it is suggested that the TPPZn-cored dendrimers indicate strong vibronic interaction and increased Jahn-Teller distortion of the prophyrin core for larger dendrimer generations. Specifically, this leads to the entirely different behaviour of the emission spectra upon substitution of the TPPH2 and TPPZn variants, which was also experimentally observed. Since TPPH2 is originally of lower symmetry the specific distortion upon dendron substitution is not expected to the same extent, which also was in agreement with the experimental findings. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
Open AccessArticle Human NK Cell Up-regulation of CD69, HLA-DR, Interferon γ Secretion and Cytotoxic Activity by Plasmacytoid Dendritic Cells is Regulated through Overlapping but Different Pathways
Sensors 2009, 9(1), 386-403; doi:10.3390/s90100386
Received: 9 October 2008 / Revised: 24 December 2008 / Accepted: 7 January 2009 / Published: 9 January 2009
Cited by 10 | PDF Full-text (317 KB) | HTML Full-text | XML Full-text
Abstract
Human plasmacytoid dendritic cells secrete high levels of IFNa and are thus implicated in the activation of NK cells. Activated NK cells are characterised by the up-regulation of CD69 and MHC class II DR expression, secretion of IFN g and enhanced cytotoxicity. We
[...] Read more.
Human plasmacytoid dendritic cells secrete high levels of IFNa and are thus implicated in the activation of NK cells. Activated NK cells are characterised by the up-regulation of CD69 and MHC class II DR expression, secretion of IFN g and enhanced cytotoxicity. We show that pDC mediate these processes by different mechanisms, some of which overlap. Human NK cells were analysed after co-culture with immature or CpG-matured blood pDC or with supernatant from these cells. Maximal CD69 expression by NK cells was mediated by supernatant from mature pDC and did not require pDC contact. Up-regulation was due in part to IFNa but also to factors in IFNa negative supernatant from immature DC. HLA-DR expression was independent of secreted molecules but required contact with immature or mature DC. Enhanced NK cytotoxicity, measured by killing of K562 targets and expression of CD107a, was mediated by multiple factors including type I IFN, supernatant from immature pDC cultures and contact with immature or mature pDC. These factors act cumulatively to enhance cytotoxcity. Thus different parameters of pDC mediated NK cell activation are regulated by distinct pathways. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
Open AccessArticle An Electrochemical DNA Biosensor Developed on a Nanocomposite Platform of Gold and Poly(propyleneimine) Dendrimer
Sensors 2008, 8(11), 6791-6809; doi:10.3390/s8116791
Received: 29 September 2008 / Revised: 22 October 2008 / Accepted: 27 October 2008 / Published: 1 November 2008
Cited by 29 | PDF Full-text (846 KB) | HTML Full-text | XML Full-text
Abstract
An electrochemical DNA nanobiosensor was prepared by immobilization of a 20mer thiolated probe DNA on electro-deposited generation 4 (G4) poly(propyleneimine) dendrimer (PPI) doped with gold nanoparticles (AuNP) as platform, on a glassy carbon electrode (GCE). Field emission scanning electron microscopy results confirmed the
[...] Read more.
An electrochemical DNA nanobiosensor was prepared by immobilization of a 20mer thiolated probe DNA on electro-deposited generation 4 (G4) poly(propyleneimine) dendrimer (PPI) doped with gold nanoparticles (AuNP) as platform, on a glassy carbon electrode (GCE). Field emission scanning electron microscopy results confirmed the codeposition of PPI (which was linked to the carbon electrode surface by C-N covalent bonds) and AuNP ca 60 nm. Voltammetric interrogations showed that the platform (GCE/PPI-AuNP) was conducting and exhibited reversible electrochemistry (E°′ = 235 mV) in pH 7.2 phosphate buffer saline solution (PBS) due to the PPI component. The redox chemistry of PPI was pH dependent and involves 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 ferro/ferricyanide (Fe(CN)63-/4-) redox probe, decreased by 81% compared to bare GCE. The conductivity (in PBS) and reduced Rct (in Fe(CN)63-/4-) values confirmed PPI-AuNP as a suitable electron transfer mediator platform for voltammetric and impedimetric DNA biosensor. The DNA probe was effectively wired onto the GCE/PPI-AuNP via Au-S linkage and electrostatic interactions. 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 Fe(CN)63-/4- redox probe. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
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Review

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Open AccessReview The Inflammasome in Host Defense
Sensors 2010, 10(1), 97-111; doi:10.3390/s100100097
Received: 2 December 2009 / Revised: 17 December 2009 / Accepted: 18 December 2009 / Published: 28 December 2009
Cited by 9 | PDF Full-text (719 KB) | HTML Full-text | XML Full-text
Abstract
Nod-like receptors have emerged as an important family of sensors in host defense. These receptors are expressed in macrophages, dendritic cells and monocytes and play an important role in microbial immunity. Some Nod-like receptors form the inflammasome, a protein complex that activates caspase-1
[...] Read more.
Nod-like receptors have emerged as an important family of sensors in host defense. These receptors are expressed in macrophages, dendritic cells and monocytes and play an important role in microbial immunity. Some Nod-like receptors form the inflammasome, a protein complex that activates caspase-1 in response to several stimuli. Caspase-1 activation leads to processing and secretion of pro-inflammatory cytokines such as interleukin (IL)-1β and IL-18. Here, we discuss recent advances in the inflammasome field with an emphasis on host defense. We also compare differential requirements for inflammasome activation in dendritic cells, macrophages and monocytes. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
Open AccessReview Dendritic Cells as Danger-Recognizing Biosensors
Sensors 2009, 9(9), 6730-6751; doi:10.3390/s90906730
Received: 2 July 2009 / Revised: 19 August 2009 / Accepted: 24 August 2009 / Published: 27 August 2009
Cited by 6 | PDF Full-text (1622 KB) | HTML Full-text | XML Full-text
Abstract
Dendritic cells (DCs) are antigen presenting cells that are characterized by a potent capacity to initiate immune responses. DCs comprise several subsets with distinct phenotypes. After sensing any danger(s) to the host via their innate immune receptors such as Toll-like receptors, DCs become
[...] Read more.
Dendritic cells (DCs) are antigen presenting cells that are characterized by a potent capacity to initiate immune responses. DCs comprise several subsets with distinct phenotypes. After sensing any danger(s) to the host via their innate immune receptors such as Toll-like receptors, DCs become mature and subsequently present antigens to CD4+ T cells. Since DCs possess the intrinsic capacity to polarize CD4+ helper cells, it is critical to understand the immunological roles of DCs for clinical applications. Here, we review the different DC subsets, their danger-sensing receptors and immunological functions. Furthermore, the cytokine reporter mouse model for studying DC activation is introduced. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
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Open AccessReview Recent Findings Concerning PAMAM Dendrimer Conjugates with Cyclodextrins as Carriers of DNA and RNA
Sensors 2009, 9(8), 6346-6361; doi:10.3390/s90806346
Received: 2 July 2009 / Revised: 6 August 2009 / Accepted: 7 August 2009 / Published: 17 August 2009
Cited by 29 | PDF Full-text (636 KB) | HTML Full-text | XML Full-text
Abstract
We have evaluated the potential use of various polyamidoamine (PAMAM) dendrimer [dendrimer, generation (G) 2-4] conjugates with cyclodextrins (CyDs) as novel DNA and RNA carriers. Among the various dendrimer conjugates with CyDs, the dendrimer (G3) conjugate with α-CyD having an average degree of
[...] Read more.
We have evaluated the potential use of various polyamidoamine (PAMAM) dendrimer [dendrimer, generation (G) 2-4] conjugates with cyclodextrins (CyDs) as novel DNA and RNA carriers. Among the various dendrimer conjugates with CyDs, the dendrimer (G3) conjugate with α-CyD having an average degree of substitution (DS) of 2.4 [α-CDE (G3, DS2)] displayed remarkable properties as DNA, shRNA and siRNA delivery carriers through the sensor function of α-CDEs toward nucleic acid drugs, cell surface and endosomal membranes. In an attempt to develop cell-specific gene transfer carriers, we prepared sugar-appended α-CDEs. Of the various sugar-appended α-CDEs prepared, galactose- or mannose-appended α-CDEs provided superior gene transfer activity to α-CDE in various cells, but not cell-specific gene delivery ability. However, lactose-appended α-CDE [Lac-α-CDE (G2)] was found to possess asialoglycoprotein receptor (AgpR)-mediated hepatocyte-selective gene transfer activity, both in vitro and in vivo. Most recently, we prepared folate-poly(ethylene glycol)-appended α-CDE [Fol-PαC (G3)] and revealed that Fol-PαC (G3) imparted folate receptor (FR)-mediated cancer cell-selective gene transfer activity. Consequently, α-CDEs bearing integrated, multifunctional molecules may possess the potential to be novel carriers for DNA, shRNA and siRNA. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
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