Browsing by Author "Nizzero, Sara"

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    A quantitative approach to discover predictors of biodistribution for drug delivery vectors in cancer.
    (2019-04-19) Nizzero, Sara; Nordlander, Peter; Ferrari, Mauro; Pimpinelli, Alberto
    Systemic aspects of cancer simultaneously offer the biggest clinical challenge and the most promising therapeutic niche in the treatment of solid tumors. In fact, treatment often fails in late stages due to the presence of metastasis, a migratory phenotype of cancer invasion. Metastases consist in cancer spread to distant organs which often presents characteristic high levels of heterogeneity and acquired resistance to treatments. Multi-stage injectable delivery vectors have proven powerful in exploiting systemic transport properties connected to physiological parameters to enhance tumor accumulation and directly improve therapeutic efficacy. The theoretical framework in which these concepts first developed is now known by the term transport oncophysics: the study of mass transport phenomena relevant to oncology with a physics-based approach. For injectable inorganic delivery vectors, the major innovation relies on the capability to tailor their organ distribution (biodistribution) upon injection. This capability comes from the controllable design of such systems, which present a discoidal shape with sizes in the micrometer range. While these systems have shown disruptive results in the treatment of triple negative breast cancer metastasis, there is still a lack of fundamental understanding on how patient-specific physiological parameters affect their biodistribution. However, it is well known that patient physiology is often dysregulated in cancer patients. These alterations can be caused by a multitude of reasons: cancer itself, the presence of concurring diseases or conditions, and previous treatment. This patient heterogeneity poses an additional challenge in therapeutic translation of injectable delivery systems. In this work, significant clinically relevant physiological parameters are screened, systematically altered, and quantitatively characterized as transport barriers for systemic delivery. Systematic in vivo biodistribution studies are conducted to address changes in biodistribution resulting from controlled alteration of specific physiological parameters. Uptake kinetic is characterized through time-resolved analysis, and investigated to inform on synergistic relationships among different parameters. A computational approach is then developed to identify a pharmacokinetic (PK) model able to predict the system behavior, and used to investigate the importance of several parameters, and functional relationships. This combined in vivo / in silico approach enables the quantitative description of mechanistic rules that determine the biodistribution of systemically injected delivery vectors. The framework that emerges from this study opens the way to a new paradigm for personalized adaptive therapy, where quantitative measurements, systematic analysis, and mathematical modeling can be combined to investigate and characterize functional relationships between quantitatively characterized physiological parameters and clinically relevant measurables for injectable inorganic delivery vectors.
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    Single-particle absorption spectroscopy by photothermal contrast
    (2014-11-21) Nizzero, Sara; Link, Stephan; Landes, Christy F; Nordlander, Peter J; Kelly, Kevin F
    Independent characterization of absorption of nano-objects is fundamental to the understanding of non-radiative properties of light matter interaction. To resolve heterogeneity in the response due to local effects, orientation or rare interactions, a single particle approach is necessary. Currently, there are very few methods that attempt to do so. Furthermore, they are limited in the type of structures and the spectral range for which they succeed. This work presents the first general and broad band method to measure the pure absorption spectrum of single particles. Photothermal microscopy is combined with a supercontinuum pulsed fiber optic tunable laser to detect a signal proportional to the pure absorption cross section of single particles at different excitation wavelengths. For the first time, a method is available to measure the pure absorption spectra of single nano-structures that exhibit spectral features from the visible to the near IR. This method is used to resolve the radiative and non-radiative properties of simple gold nanostructures, revealing the heterogeneity present in the response.
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    Single-Particle Absorption Spectroscopy by Photothermal Contrast
    (American Chemical Society, 2015) Yorulmaz, Mustafa; Nizzero, Sara; Hoggard, Anneli; Wang, Lin-Yung; Cai, Yiyu; Su, Man-Nung; Chang, Wei-Shun; Link, Stephan; Laboratory for Nanophotonics
    Removing effects of sample heterogeneity through single-molecule and single-particle techniques has advanced many fields. While background free luminescence and scattering spectroscopy is widely used, recording the absorption spectrum only is rather difficult. Here we present an approach capable of recording pure absorption spectra of individual nanostructures. We demonstrate the implementation of single-particle absorption spectroscopy on strongly scattering plasmonic nanoparticles by combining photothermal microscopy with a supercontinuum laser and an innovative calibration procedure that accounts for chromatic aberrations and wavelength-dependent excitation powers. Comparison of the absorption spectra to the scattering spectra of the same individual gold nanoparticles reveals the blueshift of the absorption spectra, as predicted by Mie theory but previously not detectable in extinction measurements that measure the sum of absorption and scattering. By covering a wavelength range of 300 nm, we are furthermore able to record absorption spectra of single gold nanorods with different aspect ratios. We find that the spectral shift between absorption and scattering for the longitudinal plasmon resonance decreases as a function of nanorod aspect ratio, which is in agreement with simulations.