Development of novel diagnostic platforms using gold nanoparticles and spectroscopy

Abstract

With the emergence of advanced molecular profiling approaches, the heterogeneous landscape of various diseases can now be accurately measured revealing that the “one-size fits all” approach to treatment is ineffective in understanding the complex pathophysiology of diseases. Personalized medicine driven by each patient’s unique molecular, physiological, and behavioral characteristics has led to a paradigm shift in healthcare. Yet the biggest bottleneck to personalized medicine is the accurate and rapid detection of targeted biomarkers that represent each disease model. Biomarker screening can accelerate clinical decisions and improve therapeutic outcomes by a priori predicting patients who will respond to treatment and those who will require alternative therapies. This dissertation describes the development of novel biomarker detection platforms, which were designed to revolutionize the accessibility of personalized medicine. First, metabolic alterations in breast cancer cells in response to small molecule inhibitors were probed with Raman spectroscopy (RS) and validated with mass spectrometry (MS). This complementary platform combining RS and MS distinguished responders from nonresponders as a function of drug dosage, drug type, and cell type. Next, an innovative biodiagnostic sensor was designed to simultaneously detect two biomarkers of myocardial infarction, where functionalized magnetic beads captured the biomarkers in human serum, gold nanostars (AuNSs) labeled with peptide biorecognition elements and Raman tags detected biomarkers via surface-enhanced Raman spectroscopy (SERS). This biosensor was validated with patient samples of various demographics and showed high precision profile in biofluids. Lastly, functionalized AuNSs present a promising platform for biomarker imaging in vivo. To facilitate clinical translation of AuNSs, the biodistribution and toxicity of AuNS were studied long-term (90 days). A correlative study combining (1) positron emission tomography (PET) imaging, (2) transmission electron micrograph (TEM) imaging, (3) gamma counts of 64Cu radiolabeled AuNSs, and (4) inductively coupled plasma mass spectrometry (ICP-MS) analysis of gold in tissues was performed to assess the biodistribution of AuNSs as a function of route of administration. These in vivo biodistribution evaluations coupled with in vitro mechanistic studies and Martini coarse-grained simulation suggested that: (1) in vivo uptake and localization of AuNSs were controlled by their cellular-level endocytosis and intracellular trafficking; (2) in vivo stability, breakdown, and ultimate reshaping were likely directed by AuNSs interaction with serum proteins and formation of protein corona; and (3) exocytosis and clearance of AuNSs were a function of the shape and surface properties of the “broken” nanoparticles that resulted from the degradation of AuNSs. Collectively, these platforms enable powerful strategies to provide an accurate prognosis to patients of their treatment outcomes early in the regimen.