title: Subsurface Super-resolution Imaging of Unstained Polymer Nanostructures.
abstract: Optical imaging has offered unique advantages in material researches, such as spectroscopy and lifetime measurements of deeply embedded materials, which cannot be matched using electron or scanning-probe microscopy. Unfortunately, conventional optical imaging cannot provide the spatial resolutions necessary for many nanoscopic studies. Despite recent rapid progress, super-resolution optical imaging has yet to be widely applied to non-biological materials. Herein we describe a method for nanoscopic optical imaging of buried polymer nanostructures without the need for extrinsic staining. We observed intrinsic stochastic fluorescence emission or blinking from unstained polymers and performed spatial-temporal spectral analysis to investigate its origin. We further applied photon localization super-resolution imaging reconstruction to the detected stochastic blinking, and achieved a spatial resolution of at least 100 nm, which corresponds to a six-fold increase over the optical diffraction limit. This work demonstrates the potential for studying the static heterogeneities of intrinsic polymer molecular-specific properties at sub-diffraction-limited optical resolutions.
authors.affiliation: Northwestern University, Department of Biomedical Engineering, Evanston, 60208, USA.
authors.forename: Ben E
authors.initials: BE
authors.lastname: Urban
authors.affiliation: Northwestern University, Department of Biomedical Engineering, Evanston, 60208, USA.|Northwestern University, Department of Mechanical Engineering, Evanston, 60208, USA.
authors.forename: Biqin
authors.initials: B
authors.lastname: Dong
authors.affiliation: Northwestern University, Department of Biomedical Engineering, Evanston, 60208, USA.
authors.forename: The-Quyen
authors.initials: TQ
authors.lastname: Nguyen
authors.affiliation: Northwestern University, Department of Biomedical Engineering, Evanston, 60208, USA.
authors.forename: Vadim
authors.initials: V
authors.lastname: Backman
authors.affiliation: Northwestern University, Department of Mechanical Engineering, Evanston, 60208, USA.
authors.forename: Cheng
authors.initials: C
authors.lastname: Sun
authors.affiliation: Northwestern University, Department of Biomedical Engineering, Evanston, 60208, USA.
authors.forename: Hao F
authors.initials: HF
authors.lastname: Zhang
mesh_terms: D008856:Microscopy, Fluorescence; D049329:Nanostructures; D061848:Optical Imaging / Q000379:methods*; D011108:Polymers / Q000737:chemistry*; D013269:Stochastic Processes
chemical_list: D011108:Polymers