Resume

• 2009

  Doctor of Philosophy (PhD)

  Chemistry

  Western University

• 2006

  English

  Master of Science (M.Sc.)

  Chemistry

  University of Saskatchewan

• 7

  A series of 18 1

  10-tetraazacyclododecane-1

  10-tetraacetic acid amide (DOTAM)-alkyl derived complexes with selected late lanthanide(III) cations (Dy3+

  Tb3+

  and Tm3+) has been synthesized; their magnetic properties have been evaluated and compared to those derived from DOTAM. Peralkylation of cyclen with corresponding N-iodoacetyl amines was utilized as the key step in the synthesis. Chemical exchange saturation transfer (CEST) spectra of the complexes have been acquired at 37 degrees C

  revealing that Tm3+-derived DOTAM-alkyl complexes possess the most favorable properties as potential paramagnetic chemical exchange saturation transfer (PARACEST) magnetic resonance imaging (MRI) contrast agents.

  Complexes of selected late period lanthanide(III) cations with 1

  10-tetraazacyclododecane-1

  10-tetraacetic acid amide (DOTAM)-alkyl ligands - A new platform for the development of paramagnetic chemical exchange saturation transfer (PARACEST) magne

  A synthetic methodology was developed for the preparation of metal-chelating ligands that possess arginine pendant groups relying on the alkylation of 1

  10-tetraazacyclododecane (cyclen) with arginine-containing electrophiles. Conditions for the selective trialkylation or peralkylation of cyclen are described

  the outcome being dependent on the nature of the arginine-derived electrophile and the solvent used for the reaction. Lanthanide metal complexes of the ligands prepared by the described route were evaluated for their suitability as PARACEST contrast agents for use in magnetic resonance imaging. The Dy3+ and Tm3+ complexes display CEST effects that are associated with the amide protons proximate to the metal center. These signals exhibit pH dependence in the range of 6.08.0 and thus may have the potential for pH measurement in physiological range

  DOTAM-type ligands possessing arginine pendant groups for use in PARACEST MRI

  A series of structurally modified Tm3+ DOTAM-alkyl complexes as potential PARACEST MRI contrast agents has been synthesized with the aim to decrease the overall positive charge associated with these molecules and increase their biocompatibility. Two types of structural modification have been performed

  an introduction of terminal carboxylate arms to the alkyl side chains and a conjugation of one of the alkyl side chains with aspartic acid. Detailed evaluation of the magnetic resonance imaging chemical exchange contrast associated with the structurally modified contrast agents has been performed. In contrast to the acutely toxic Tm3+ DOTAM-alkyl complexes

  the structurally modified compounds were found to be tolerated well during in vivo MRI studies in mice; however

  only the aspartic acid modified chelates produced an amide proton-based PARACEST signal.

  Introduction of Peripheral Carboxylates to Decrease the Charge on Tm3+ DOTAM-Alkyl Complexes: Implications for Detection Sensitivity and in Vivo Toxicity of PARACEST MRI Contrast Agents

  The polysaccharide

  inulin

  is considered the clinical gold standard for measuring glomerular filtration rate (GFR)

  an assessment of kidney filtering capacity and renal function

  and therefore

  is a prognostic indicator of chronic kidney disease (CKD). The classic method of measuring GFR is laborious

  tedious and invasive. Therefore

  estimated GFR (eGFR) has become the favoured measurement

  but unfortunately suffers in its accuracy. Here

  we describe the development of a near infrared dye-labeled inulin

  Cy7.5-inulin conjugate

  for use as an optical probe to accurately and non-invasively measure GFR in patients by transcutaneous pulse dye densitometer (TPDD). We have characterized the modifications made to inulin and the dye-polysaccharide conjugate by a number of analytical techniques and demonstrated that it is stable under experimental in vivo conditions. To this end

  the probe has been successfully used in a pig model to accurately measure GFR non-invasively.

  The development of a near infrared inulin optical probe for measuring glomerular filtration rate

  Herein we present a method for the simultaneous

  multiple conjugation of alkynyl-(Gd(III)-DOTA) moieties to a PNA oligomer possessing a domain of azide residues. This is achieved in a single Huisgen type coppercatalyzed azide alkyne cycloaddition (CuAAC) reaction after the oligomer assembly is completed. A triplex formed between the labelled PNA and riboadenylic acid

  [(Gd(III)-DOTA)(4)-PNA](2):poly(rA)

  displayed higher relaxivities at any field strength compared to the single-stranded probe at the same concentration of Gd3+ ions as determined by nuclear magnetic resonance dispersion (NMRD) studies.

  Synthesis of a poly(Gd(III)-DOTA)-PNA conjugate as a potential MRI contrast agent via post-synthetic click chemistry functionalization

• 4

  A series of 1

  10-tetraazacyclododecane-1

  7-triyl) triacetate monoamide (DO3A-monoanilide) complexes Dy3+ and Tm3+ were prepared and their magnetic properties evaluated in the context of their potential use as pH sensors. The ligands varied by para-substitution of the aniline moiety and represent electron-withdrawing and electron-donating groups. Only the Tm3+ complexes produced chemical exchange saturation transfer (CEST) spectra with CEST intensities due to the amide proton ranging from 1% to 8%. A maximum CEST signal was observed under slightly alkaline conditions (pH similar to 8) when electron-donating groups were present

  whereas the strongly electron-withdrawing nitro group produced a maximum CEST at neutral pH (pH = 7). The T-1 and T-2 relaxivities of the Dy3+ and Tm3+ complexes were also assessed. The T1 relaxivities of the Dy3+ and Tm3+ complexes were both low (r(1) <= 0.3 mM(-1) s(-1)

  25 degrees C

  pH = 7) but

  as expected

  the Dy3+ complexes had much higher T-2 relaxivities (r(2) = 2-7 mM(-1) s(-1)

  25 degrees C

  pH = 7) as compared to the Tm3+-based chelates (r(2) <= 0.09 mM(-1) s(-1)

  25 degrees C

  pH = 7).

  Dysprosium(III) and thulium(III) complexes of DO3A-monoanilides: an investigation of electronic effects on their relaxometric and amide-based PARACEST properties

  Robert H. E. Hudso

  Robert Bartha

  Mojmir Suchý

  Adam A. H. Elmehriki

  Todd K. Stevens

  The Tm(3+) chelate of DOTAM displayed a paraCEST signal associated with the highly shifted amide proton signal at approximately -100 ppm that was beyond the frequency of macromolecule magnetization transfer.

  DOTAM-based ParaCEST agent favoring TSAP geometry for enhanced amide proton chemical shift dispersion and temperature sensitivity

  Robert H. E. Hudson

  Robert Bartha

  Mark S. Workentin

  Nevin McVicar

  Pierangelo Gobbo

  A contrast agent suitable for magnetic resonance imaging based on small

  water soluble gold nanoparticles (AuNP) conjugated to over 50 Gd3+ chelators has been prepared by using an interfacial Michael addition in aqueous media

  Water soluble gold nanoparticles functionalized with gadolinium through Michael addition for use as a MRI contrast agent

  By fine-tuning the water molecule exchange rate at 37 degrees C

  the transverse relaxivity has been increased by 2 to 30 times compared with previously studied Dy3+-based chelates. Polymerization or dendrimerization of the optimal chelate could yield a highly sensitive

  molecule-sized T-2 contrast agent for improved molecular imaging applications

  Maximizing T-2-Exchange in Dy(3+)DOTA-(amide)(X) Chelates: Fine-Tuning the Water Molecule Exchange Rate for Enhanced T-2 Contrast in MRI

  Post-traumatic osteoarthritis (PTOA) is a common and serious complication after anterior cruciate ligament (ACL) rupture. One of the driving factors in the progression to PTOA is perpetuation of inflammatory response to injury into a low-grade chronic inflammation. MRI is very limited in the assessment of low-grade inflammation in vivo. Contrast-enhanced MRI can measure inflammatory vasodilation but lacks molecular specificity and ability to assess inflammation in low-perfused tissues such as ligaments and cartilage. Aim of this research was to develop a peptide-based imaging probe that target hyaluronan (HA)-mediated inflammatory signaling through interactions with HA and HA-cell receptors

  Imaging low-grade inflammation in post-traumatic osteoarthritis

  The C–X–C chemokine receptor 4 (CXCR4) has been shown to be overexpressed in at least 23 types of cancer

  including prostate cancer which has been shown to have a significant distinction of expression rates between cancerous compared to healthy or benign tissue. In an attempt to exploit the difference in expression

  we have synthesized a derivative of T140

  a peptide antagonist for CXCR4

  containing a fluorescent 4-amino-1

  8-naphthalimide appended with a di-(2-picolyl)amine binding unit to chelate rhenium or technetium-99m for fluorescence or SPECT imaging. The rhenium-coordinated variant was shown to have similar binding affinity for the receptor as T140 and showed specific uptake by fluorescence microscopy in CXCR4 expressing cells. The peptide was radiolabelled with technetium-99m in decay corrected radiochemical yields ranging from 60–85%

  radiochemical purities >95%

  and molar activities of 36–44 GBq μmol−1. The technetium-99m labelled peptide showed two-fold higher uptake in U87 cells expressing CXCR4 compared to non-transfected cells. Ex vivo biodistribution studies were performed using the technetium-99m labelled peptide in NOD/SCID mice bearing tumors derived from U87 cells with CXCR4. Tumor uptake of 0.51 ± 0.09% ID g−1 was observed two-hours post-injection. Our novel T140 derivative is suitable for imaging of CXCR4 expression by confocal microscopy. Further structural modifications to the peptide or metal complex may result in improved biodistribution for use in SPECT imaging of CXCR4 expressing tumors.

  A dual modality 99m Tc/Re (i)-labelled T140 analogue for imaging of CXCR4 expression

  Robert H.E. Hudson

  Robert Bartha

  Alex Li

  Kirby Chicas

  A comprehensive series of lanthanide chelates has been prepared with a tetrapropargyl DOTAM type ligand. The complexes have been characterized by a combination of 1H NMR

  single-crystal X-ray crystallography

  CEST and relaxation studies and have also been evaluated for potential use as paramagnetic chemical exchange saturation transfer (ParaCEST) contrast agents in magnetic resonance imaging (MRI)

  ParaCEST MRI contrast agents capable of derivatization via ‘click’ chemistry

  Robert H. E. Hudson

  Robert Bartha

  Mojmir Suchy

  Adam H. Elmehriki

  Todd K. Stevens

  Overcoming biological MT Effects by use of ParaCEST MRI contrast agents possessing highly shifted amide proton signals

  Synthesis and characterization of new ferrocene peptide conjugates

  Three classes of diamine linked ferrocene (Fc)-conjugates were prepared and their properties were investigates in solution and the solid state: (a) acyclic diamine-linked 1

  n'-Fc conjugates

  (b) acyclic diamine-linked 1

  n'-Fc peptide conjugates

  and (c) cyclic 1

  n'-Fc-peptide diamine conjugates. In all cases

  the synthetic procedure started from 1

  1'-ferrocenecarboxylic acid methyl ester or 1

  1'-ferrocene dicarboxylic acid or their amino acid conjugates followed by coupling with diaminoalkanes. The resulting conjugates exhibit H-bonding as is evident by temperature and

  in some cases

  concentration-dependent NMR shifts and in the solid-state structure of one of the conjugates. Our studies show that the structural properties of Fc-diamine-linked systems are different from those of the related cystamine conjugates

  presumably due to the enhanced flexibility of the conjugates.

  Synthesis and characterization of new ferrocene peptide conjugates

  Robert H. E. Hudson

  Contrast agents based on lanthanide tetra-propargyl DOTAM complexes suitable for temperature mapping by magnetic resonance spectroscopy (MRS) are reported. Sensitivity values from 1.05 ppm/°C to 1.76 ppm/°C were determined which represents an improvement of 2–3 times over currently available lanthanide temperature-responsive contrast agents

  Contrast agents possessing high temperature sensitivity

  he receptor for hyaluronan mediated motility (RHAMM

  gene name HMMR) belongs to a group of proteins that bind to hyaluronan (HA)

  a high-molecular weight anionic polysaccharide that has pro-angiogenic and inflammatory properties when fragmented. We propose to use a chemically synthesized

  truncated version of the protein (706–767)

  7 kDa RHAMM

  as a target receptor in the screening of novel peptide-based therapeutic agents. Chemical synthesis by Fmoc-based solid-phase peptide synthesis

  and optimization using pseudoprolines

  results in RHAMM protein of higher purity and yield than synthesis by recombinant protein production. 7 kDa RHAMM was evaluated for its secondary structure

  ability to bind the native ligand

  HA

  and its bioactivity. This 62-amino acid polypeptide replicates the HA binding properties of both native and recombinant RHAMM protein

  A truncated RHAMM protein for discovering novel therapeutic peptides

  Mark

  Milne PhD.

  Western University

  London Health Sciences Centre (LHSC)

  London Health Sciences Centre (LHSC)

  University of Texas Southwestern

  Development of contrast agents for MRI

  Postdoctoral Fellow

  Dallas/Fort Worth Area

  University of Texas Southwestern

  London Health Sciences Centre (LHSC)

  Lecturer

  Organic Chemistry 2003b

  Western University

  Research Officer

  Western University

  Research Scientist and Coordinator

  London Health Sciences Centre (LHSC)

• Mark Milne - Google Scholar Citations

  Analytical Chemistry

  Chemistry

  Medical Imaging

  Organic Synthesis

  Standard Operating Procedure (SOP)

  High-Performance Liquid Chromatography (HPLC)

  Scientific Writing

  Laboratory Skills

  Data Analysis

  Organic Chemistry

  Budget Management

  Nuclear Magnetic Resonance (NMR)

  Chromatography

  Healthcare

  MRI

  Pharmaceutical Industry

  Mass Spectrometry

  Research and Development (R&D)

  Cancer

  UV/Vis Spectroscopy

  ParaCEST Agents: Design

  Discovery

  and Implementation

  ParaCEST Agents: Design

  Discovery

  and Implementation

  The Cu+-catalyzed Huisgen [3+2] cycloaddition has been used to elaborate analogues of a candidate PARACEST MRI contrast agent

  which is a complex of Eu3+ with DOTAM-Gly-Phe-OH. Analogues possessing either one L-tyrosine in place of an L-phenylalanine

  or with all four phenylalanine units replaced

  were transformed into Tyr(O-propargyl) substrates for \"click\" chemistry. Conjugation of the Eu3+-DOTAM derivatives with a spectrum of azides

  including simple hydrophilic

  hydrophobic

  and aromatic groups

  propyl glucoside

  and a nucleoside were successful. The magnetic resonance properties of the resultant conjugates were examined

  and their chemical exchange saturation transfer (CEST) properties are reported.

  Mono- and Tetraalkyne Modified Ligands and Their Eu3+ Complexes - Utilizing \"Click\" Chemistry to Expand the Scope of Conjugation Chemistry

  Robert H. E. Hudson

  Robert Bartha

  Mojmír Suchý

  Nevin McVicar

  Melissa Lewis

  A series of Dy3+ and Tm3+ tetra-substituted DOTAM paraCEST agents incorporating para-substituted anilines has been synthesized and their paraCEST and relaxation properties evaluated

  MRI ParaCEST agents that improve amide based pH measurements by limiting inner sphere water T2 exchange

  Here we report the polarization of the solvent OH protons by SABRE using standard iridium-based catalysts under slightly acidic conditions. Solvent polarization was observed in the presence of a variety of structurally similar N-donor substrates while no solvent enhancement was observed in the absence of substrate or para-hydrogen (p-H-2). Solvent polarization was sensitive to the polarizing field and catalyst: substrate ratio in a manner similar to that of substrate protons. SABRE experiments with pyridine-d(5) suggest a mechanism where hyperpolarization is transferred from the free substrate to the solvent by chemical exchange while measured hyperpolarization decay times suggest a complimentary mechanism which occurs by direct coordination of the solvent to the catalytic complex. We found the solvent hyperpolarization to decay nearly 3 times more slowly than its characteristic spin-lattice relaxation time suggesting that the hyperpolarized state of the solvent may be sufficiently long lived (similar to 20 s) to hyperpolarize biomolecules having exchangeable protons. This route may offer future opportunities for SABRE to impact metabolic imaging.

  Nuclear spin hyperpolarization of the solvent using signal amplification by reversible exchange (SABRE)