A Plasmonic Gold Nanostar Theranostic Probe for In Vivo Tumor Imaging and Photothermal Therapy.

Melodi Javid Whitley, MD, PhD
Assistant Professor of Dermatology
Assistant Program Director for Trainee Research
Director of Transplant Dermatology

I am a physician scientist focused on the dermatologic care of solid organ transplant recipients.  Clinically, I manage the the complex dermatologic side effects of immunosuppression with a focus on high-risk skin cancer.  My research focuses on understanding the drivers of cutaneous malignancy in this population using translational approaches.

Dr. Vaidyanathan is a professor in the Department of Radiology.  He is a member of the Nuclear Medicine track of the Medical Physics Graduate Program.  His research involves development of radiopharmaceuticals especially for oncologic applications.  Some of the projects he is involved in are given below.

I.          New methods of radiohalogenating antibodies and its variants 

a) Development of newer residualizing agents for the radiohalogenation of internalizing monoclonal antibodies.

b)  Development of fluorine-18 labeled residualizing agents for labeling nanobodies.

c) Pre-targeting approach via bioorthogonal chemistry for in vivo labeling of antibodies and nanobodies with ¹⁸F and ²¹¹At.

d)  Methods to label antibodies pre-conjugated with a prosthetic group of the tin precursor of residualizing agents.

e) Multimodal prosthetic groups for labeling antibodies and peptides with multiple radioisotopes.

II.         MIBG Analogs for PET imaging

Radioiodinated MIBG is used in the diagnosis of the pathophysiology of the heart as well as neuroendocrine tumors such as neuroblastoma (NB).  Design and development of newer fluorine-18 labeled MIBG analogues useful in the PET imaging of NB as well as that of myocardial diseases.

III. Noninvasive Imaging of Alkylguanine-DNA alkyltransferase (AGT) 

AGT is a DNA repair protein and is primarily responsible for drug resistance in alkylator chemotherapy. An inverse correlation has been established between the tumor AGT content and the therapeutic outcome. The amount of AGT varies from tumor to tumor and within a group of patients of similar cancer. Thus, it is important to quantify tumor AGT of individual patients before administering alkylator chemotherapy. Our goal is to develop radiolabeled agents with which AGT can be quantified in a noninvasive manner by PET or SPECT imaging. 

IV. PSMA targeting for prostate cancer therapy 

Development of At-211 labeled urea-based inhibitor of Prostate-specific membrane antigen.

The overall objective of our laboratory is the development of novel radioactive compounds for improving the diagnosis and treatment of cancer. This work primarily involves radiohalo-genation of biomolecules via site-specific approaches, generally via demetallation reactions. Radionuclides utilized for imaging include I-123, I-124 and F-18, the later two being of particular interest because they can be used for the quantification of biochemical and physiological processes in the living human through positron emission tomography. For therapy, astatine-211 decays by the emission of alpha-particles, a type of radiation considerably more cytotoxic that the beta-particles used in conventional endoradiotherapy. The range of At-211 alpha particles is only a few cell diameters, offering the possibility of extremely focal irradiation of malignant cells while leaving neighboring cells intact. Highlights of recent work include: a)
development of reagents for protein and peptide radioiodination that decrease deiodination in vivo by up to 100-fold, b) demonstration that At-211 labeled monoclonal antibodies are effective in the treatment of a rat model of neoplastic meningitis, c) synthesis of a thymidine analogue labeled with At-211 and the demonstration that this molecule is taken up in cellular DNA with highly cytotoxicity even at levels of only one atom bound per cell and d) development of
radiohalobenzylguanidines which are specifically cytotoxic for human neuroblastoma cells.

• Our lab's research focus lies primarily in developing novel quantitative imaging systems, reconstruction algorithms and analysis methods.  My major expertise is in preclinical CT.
• Currently, we are particularly interested in developing novel strategies for spectral CT imaging using nanoparticle-based contrast agents for theranostics (i.e. therapy and diagnostics).
• We are also engaged in developing new approaches for multidimensional CT image reconstruction suitable to address difficult undersampling cases in cardiac and spectral CT (dual energy and photon counting) using compressed sensing and/or deep learning.

• We are involved in co-clinical cancer trials and I serve as the Principal Investigator on the U24 Duke Preclinical Research Resources for Quantitative Imaging Biomarkers part of the NCI Co-Clinical Imaging Research Resources Program network (CIRP).

Dr. Tuan Vo-Dinh is R. Eugene and Susie E. Goodson Distinguished Professor of Biomedical Engineering, Professor of Chemistry, and Director of The Fitzpatrick Institute for Photonics.

Dr. Vo-Dinh’s research activities and interests involve biophotonics, nanophotonics, plasmonics, laser-excited luminescence spectroscopy, room temperature phosphorimetry, synchronous luminescence spectroscopy, and surface-enhanced Raman spectroscopy for multi-modality bioimaging, and theranostics (diagnostics and therapy) of diseases such as cancer and infectious diseases.

We have pioneered the development of a new generation of gene biosensing probes using surface-enhanced Raman scattering (SERS) detection with “Molecular Sentinels” and Plasmonic Coupling Interference (PCI) molecular probes for multiplex and label-free detection of nucleic acid biomarkers (DNA, mRNA, microRNA) in early detection of a wide variety of diseases.

In genomic and precision medicine, nucleic acid-based molecular diagnosis is of paramount importance with many advantages such as high specificity, high sensitivity, serotyping capability, and mutation detection. Using SERS-based plasmonic nanobiosensors and nanochips, we are developing novel nucleic acid detection methods that can be integrated into lab-on-a-chip systems for point-of-care diagnosis  (e.g., breast, GI cancer) and global health applications (e.g., detection of malaria and dengue).

In bioimaging, we are developing a novel multifunctional gold nanostar (GNS) probe for use in multi-modality bioimaging in pre-operative scans with PET, MRI and CT, intraoperative margin delineation with optical imaging, SERS and two-photon luminescence (TPL). The GNS can be used also for cancer treatment with plasmonics enhanced photothermal therapy (PTT), thus providing an excellent platform for seamless diagnostics and therapy (i.e., theranostics). Preclinical studies have shown its great potential for cancer diagnostics and therapeutics for future clinical translation.

For fundamental studies, various nanobiosensors are being developed for monitoring intracellular parameters (e.g., pH) and biomolecular processes (e.g., apoptosis, caspases), opening the possibility for fundamental molecular biological research as well as biomedical applications (e.g., drug discovery) at the single cell level in a systems biology approach. For point of care diagnostics, nanoprobes and nanochips with highly multiplex SERS detection and imaging use artificial intelligence and machine learning for data analysis.

Our research activities in immunotherapy involve unique plasmonics-active gold “nanostars.” These star-shaped nanobodies made of gold work like “lightning rods,” concentrating the electromagnetic energy at their tips and allowing them to capture photon energy more efficiently when irradiated by laser light. Teaming with medical collaborators, we have developed a novel cancer treatment modality, called synergistic immuno photothermal nanotherapy (SYMPHONY), which combines immune-checkpoint inhibition and gold nanostar–mediated photothermal immunotherapy that can unleash the immunotherapeutic efficacy of checkpoint inhibitors. This combination treatment can eradicate the primary tumors as well as distant “untreated” tumors, and induce immunologic memory like a “anti-cancer vaccine” effect in murine model.