Honors & Awards


  • Faculty of Health Sciences Graduate Programs Outstanding Thesis Award, McMaster University (2017)
  • Faculty of Health Sciences Graduate Programs Excellence Award, McMaster University (2016)
  • McMaster Graduate Studies International Excellence Award, McMaster University (2014-2015)
  • Outstanding Oral Presentation Award, Faculty of Health Sciences, McMaster University (2014)
  • Chemical Biology Travel Award, McMaster University (2012-2013)
  • McMaster Graduate Studies International Excellence Award, McMaster University (2012-2013)

Professional Education


  • Doctor of Philosophy, McMaster University (2016)
  • Bachelor of Science, King Saud University (2009)

Stanford Advisors


Patents


  • Aimen Zlitni, John F. Valliant. "CanadaTargeted Molecular Imaging Contrast Agents.", Aug 1, 2015

All Publications


  • Development of prostate specific membrane antigen targeted ultrasound microbubbles using bioorthogonal chemistry. PloS one Zlitni, A., Yin, M., Janzen, N., Chatterjee, S., Lisok, A., Gabrielson, K. L., Nimmagadda, S., Pomper, M. G., Foster, F. S., Valliant, J. F. 2017; 12 (5): e0176958

    Abstract

    Prostate specific membrane antigen (PSMA) targeted microbubbles (MBs) were developed using bioorthogonal chemistry. Streptavidin-labeled MBs were treated with a biotinylated tetrazine (MBTz) and targeted to PSMA expressing cells using trans-cyclooctene (TCO)-functionalized anti-PSMA antibodies (TCO-anti-PSMA). The extent of MB binding to PSMA positive cells for two different targeting strategies was determined using an in vitro flow chamber. The initial approach involved pretargeting, where TCO-anti-PSMA was first incubated with PSMA expressing cells and followed by MBTz, which subsequently showed a 2.8 fold increase in the number of bound MBs compared to experiments performed in the absence of TCO-anti-PSMA. Using direct targeting, where TCO-anti-PSMA was linked to MBTz prior to initiation of the assay, a 5-fold increase in binding compared to controls was observed. The direct targeting approach was subsequently evaluated in vivo using a human xenograft tumor model and two different PSMA-targeting antibodies. The US signal enhancements observed were 1.6- and 5.9-fold greater than that for non-targeted MBs. The lead construct was also evaluated in a head-to-head study using mice bearing both PSMA positive or negative tumors in separate limbs. The human PSMA expressing tumors exhibited a 2-fold higher US signal compared to those tumors deficient in human PSMA. The results demonstrate both the feasibility of preparing PSMA-targeted MBs and the benefits of using bioorthogonal chemistry to create targeted US probes.

    View details for DOI 10.1371/journal.pone.0176958

    View details for PubMedID 28472168

  • Catching Bubbles: Targeting Ultrasound Microbubbles Using Bioorthogonal Inverse-Electron-Demand Diels-Alder Reactions ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Zlitni, A., Janzen, N., Foster, F. S., Valliant, J. F. 2014; 53 (25): 6459-6463

    View details for DOI 10.1002/anie.201402473

    View details for Web of Science ID 000337095900025

    View details for PubMedID 24829138

  • I-125-Tetrazines and Inverse-Electron-Demand Diels-Alder Chemistry: A Convenient Radioiodination Strategy for Biomolecule Labeling, Screening, and Biodistribution Studies BIOCONJUGATE CHEMISTRY Albu, S. A., Al-Karmi, S. A., Vito, A., Dzandzi, J. P., Zlitni, A., Beckford-Vera, D., Blacker, M., Janzen, N., Patel, R. M., Capretta, A., Valliant, J. F. 2016; 27 (1): 207-216

    Abstract

    A convenient method to prepare radioiodinated tetrazines was developed, such that a bioorthogonal inverse electron demand Diels-Alder reaction can be used to label biomolecules with iodine-125 for in vitro screening and in vivo biodistribution studies. The tetrazine was prepared by employing a high-yielding oxidative halo destannylation reaction that concomitantly oxidized the dihydrotetrazine precursor. The product reacts quickly and efficiently with trans-cyclooctene derivatives. Utility was demonstrated through antibody and hormone labeling experiments and by evaluating products using standard analytical methods, in vitro assays, and quantitative biodistribution studies where the latter was performed in direct comparison to Bolton-Hunter and direct iodination methods. The approach described provides a convenient and advantageous alternative to conventional protein iodination methods that can expedite preclinical development and evaluation of biotherapeutics.

    View details for DOI 10.1021/acs.bioconjchem.5b00609

    View details for Web of Science ID 000368651600023

    View details for PubMedID 26699913

  • Synthesis, characterization and radiolabeling of carborane-functionalized tetrazines for use in inverse electron demand Diels-Alder ligation reactions JOURNAL OF ORGANOMETALLIC CHEMISTRY Genady, A. R., Tan, J., El-Zaria, M. E., Zlitni, A., Janzen, N., Valliant, J. F. 2015; 791: 204-213
  • The synthesis, magnetic purification and evaluation of Tc-99m-labeled microbubbles NUCLEAR MEDICINE AND BIOLOGY Lazarova, N., Causey, P. W., Lemon, J. A., Czorny, S. K., Forbes, J. R., Zlitni, A., Genady, A., Foster, F. S., Valliant, J. F. 2011; 38 (8): 1111-1118

    Abstract

    Ultrasound (US) contrast agents based on microbubbles (MBs) are being investigated as platforms for drug and gene delivery. A methodology for determining the distribution and fate of modified MBs quantitatively in vivo can be achieved by tagging MBs directly with (99m)Tc. This creates the opportunity to employ dual-modality imaging using both US and small animal SPECT along with quantitative ex vivo tissue counting to evaluate novel MB constructs.A (99m)Tc-labeled biotin derivative ((99m)TcL1) was prepared and incubated with streptavidin-coated MBs. The (99m)Tc-labeled bubbles were isolated using a streptavidin-coated magnetic-bead purification strategy that did not disrupt the MBs. A small animal scintigraphic/CT imaging study as well as a quantitative biodistribution study was completed using (99m)TcL1 and (99m)Tc-labeled bubbles in healthy C57Bl-6 mice.The imaging and biodistribution data showed rapid accumulation and retention of (99m)Tc-MBs in the liver (68.2±6.6 %ID/g at 4 min; 93.3±3.2 %ID/g at 60 min) and spleen (214.2±19.7 %ID/g at 4 min; 213.4±19.7 %ID/g at 60 min). In contrast, (99m)TcL1 accumulated in multiple organs including the small intestine (22.5±3.6 %ID/g at 4 min; 83.4±5.9 %ID/g at 60 min) and bladder (184.0±88.1 %ID/g at 4 min; 24.2±17.7 %ID/g at 60 min).A convenient means to radiolabel and purify MBs was developed and the distribution of the labeled products determined. The result is a platform which can be used to assess the pharmacokinetics and fate of novel MB constructs both regionally using US and throughout the entire subject in a quantitative manner by employing small animal SPECT and tissue counting.

    View details for DOI 10.1016/j.nucmedbio.2011.04.008

    View details for Web of Science ID 000298070400005

    View details for PubMedID 21741260