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Zimmerman JF, Ardoña HAM, Pyrgiotakis G, Dong J, Moudgil B, Demokritou P, Parker KK. Scatter Enhanced Phase Contrast Microscopy for Discriminating Mechanisms of Active Nanoparticle Transport in Living Cells. NANO LETTERS 2019; 19:793-804. [PMID: 30616354 PMCID: PMC6588408 DOI: 10.1021/acs.nanolett.8b03903] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Understanding the uptake and transport dynamics of engineered nanomaterials (ENMs) by mammalian cells is an important step in designing next-generation drug delivery systems. However, to track these materials and their cellular interactions, current studies often depend on surface-bound fluorescent labels, which have the potential to alter native cellular recognition events. As a result, there is still a need to develop methods capable of monitoring ENM-cell interactions independent of surface modification. Addressing these concerns, here we show how scatter enhanced phase contrast (SEPC) microscopy can be extended to work as a generalized label-free approach for monitoring nanoparticle uptake and transport dynamics. To determine which materials can be studied using SEPC, we turn to Lorenz-Mie theory, which predicts that individual particles down to ∼35 nm can be observed. We confirm this experimentally, demonstrating that SEPC works for a variety of metal and metal oxides, including Au, Ag, TiO2, CeO2, Al2O3, and Fe2O3 nanoparticles. We then demonstrate that SEPC microscopy can be used in a quantitative, time-dependent fashion to discriminate between distinct modes of active cellular transport, including intracellular transport and membrane-assisted transport. Finally, we combine this technique with microcontact printing to normalize transport dynamics across multiple cells, allowing for a careful study of ensemble TiO2 nanoparticle uptake. This revealed three distinct regions of particle transport across the cell, indicating that membrane dynamics play an important role in regulating particle flow. By avoiding fluorescent labels, SEPC allows for a rational exploration of the surface properties of nanomaterials in their native state and their role in endocytosis and cellular transport.
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Affiliation(s)
- John F. Zimmerman
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts, USA
| | - Herdeline Ann M. Ardoña
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts, USA
| | - Georgios Pyrgiotakis
- Center for Nanotechnology and Nanotoxicology, Harvard T.H. Chan School of Public Health, Harvard University, Cambridge, MA, 02138, USA
| | - Jiaqi Dong
- Department of Materials Science & Engineering and Particle Engineering Research Center, PO BOX 116135, University of Florida, Gainesville, FL, 32611, USA
| | - Brij Moudgil
- Department of Materials Science & Engineering and Particle Engineering Research Center, PO BOX 116135, University of Florida, Gainesville, FL, 32611, USA
| | - Philip Demokritou
- Center for Nanotechnology and Nanotoxicology, Harvard T.H. Chan School of Public Health, Harvard University, Cambridge, MA, 02138, USA
| | - Kevin Kit Parker
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts, USA
- Corresponding Author: Professor Kevin Kit Parker, 29 Oxford St., Pierce Hall 321, Cambridge, Massachusetts, 02138, USA. ; Fax: +(617) 495 9837; Tel: +(617) 495 2850
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