We present a novel approach for characterizing surfaces utilizing super-resolution fluorescence microscopy with subdiffraction limit spatial resolution. Thermoplastic surfaces were activated by UV/O3 or O2 plasma treatment under various conditions to generate pendant surface-confined carboxylic acids (-COOH). These surface functional groups were then labeled with a photoswitchable dye and interrogated using single-molecule, localization-based, super-resolution fluorescence microscopy to elucidate the surface heterogeneity of these functional groups across the activated surface. Data indicated nonuniform distributions of these functional groups for both COC and PMMA thermoplastics with the degree of heterogeneity being dose dependent. In addition, COC demonstrated relative higher surface density of functional groups compared to PMMA for both UV/O3 and O2 plasma treatment. The spatial distribution of -COOH groups secured from super-resolution imaging were used to simulate nonuniform patterns of electroosmotic flow in thermoplastic nanochannels. Simulations were compared to single-particle tracking of fluorescent nanoparticles within thermoplastic nanoslits to demonstrate the effects of surface functional group heterogeneity on the electrokinetic transport process. (Chemical Equation Presented).
Bibliographical noteFunding Information:
The authors would like to thank the National Institutes of Health (R21HG006278; P41EB020594), the National Science Foundation (1507577) Research Fund (1.130090.01) of Ulsan National Institute of Science and Technology, and Roche for financial support of this work. C.E.O. thanks the National Science Foundation for support through a summer fellowship program (EAPSI), and J.M.J. thanks the ACS Division of Analytical Chemistry and the Society for Analytical Chemists of Pittsburgh for funding. Furthermore, the authors thank Dr. Mateusz Hupert for his SEM studies of PMMA as well as Dr. Franklin Uba for his assistance in the construction of the single molecule electrophoresis optical system and thoughtful discussions.
© 2016 American Chemical Society.
ASJC Scopus subject areas
- Analytical Chemistry