Synthesis and Characterization of Fluorescent Protein Nanoparticles to Image and Treat Cancer
Dr. Leonard C. Uitenham
Fluorescent proteins are invaluable tools that enable tracking of gene expression, cell cycle, and cancer cells in living animals. Fluorescent proteins originated from the jellyfish Aequorea Victoria, which expresses the green fluorescent protein (GFP). Fluorescent proteins were awarded the 2008 Nobel Prize in Chemistry. Traditional fluorescent proteins are limited in wavelengths, consume oxygen, and produce a stoichiometric amount of hydrogen peroxide upon chromophore formation. Far-red fluorescent proteins are desirable for imaging deeper in living animals because less light is scattered, absorbed, and/or reemitted by endogenous biomolecules. Dr. Rodriguez developed a new class of fluorescent protein by evolving an allophycocyanin alpha-subunit from a cyanobacterium, Trichodesmium erythraeum. The selected protein was named small Ultra-Red Fluorescent Protein (smURFP), which is biophysically as bright as enhanced green fluorescent protein (eGFP). smURFP is currently the brightest far-red fluorescent protein available. Recently, patented radioactive fluoride chemistry developed by Drs. Rodriguez & Richard Ting (Weill Cornell Medicine) was tested in humans with positron emission tomography (PET) imaging and allows for improved lymph node mapping compared to clinically used magnetic resonance imaging (MRI) and single-photon emission computerized tomography (SPECT) agents. These new chemicals labelled with radioactive fluoride can miss small anatomical features and require extensive synthesis for attaching drugs and/or dyes for photodynamic therapy. smURFP was evolved to express extremely well in E. coli and gram quantities are easily purified in a day. smURFP is extremely pH and temperature stable, which are excellent properties to develop materials for biomedical imaging of human anatomy and disease. I purified the fluorescent protein, smURFP, and synthesized fluorescent protein nanoparticles. Synthesis was optimized by varying protein concentration, protein cross-linker, and sonication time. Fluorescent protein nanoparticles were characterized by size and fluorescence. I encapsulated solvatochromic, fluorescent dyes to safely mimic cancer drugs, such as doxorubicin, and analyzed incorporation. smURFP nanoparticles easily encapsulate small molecule drugs. The smURFP is easily modified for photodynamic therapy and PET imaging. The smURFP nanoparticles should enhance PET signal to image small anatomical features and very small, metastatic tumors in humans. These nanoparticles encapsulate drugs and modification allows for photodynamic therapy for treatment.
Walker, Angelo, "Synthesis and Characterization of Fluorescent Protein Nanoparticles to Image and Treat Cancer" (2018). Undergraduate Research and Creative Inquiry Symposia. 3.