title: Neurotypic cell attachment and growth on III-nitride lateral polarity structures.
abstract: III-nitride materials have recently received increasing levels of attention for their potential to successfully interface with, and sense biochemical interactions in biological systems. Expanding on available sensing schemes (including transistor-based devices,) a III-N lateral polarity structure capable of introducing quasi-phase matching through a periodic polarity grating presents a novel platform for second harmonic generation. This platform constitutes a non-linear optical phenomenon with exquisite sensitivity to the chemical state of a surface or interface. To characterize the response of a biological system to the nanostructured lateral polarity structures, we cultured neurotypic PC12 cells on AlGaN with varying ratios of Al:Ga - 0, 0.4, 0.6, and 1 - and on surfaces of varying pitch to the III-polar vs. N-polar grating - 5, 10, 20 and 50 μm. While some toxicity associated with increasing Al is observed, we documented and quantified trends in cell responses to the local material polarity and nanoscale roughness. The nitrogen-polar material has a significantly higher nanoscale roughness than III-polar regions, and a 80-200 nm step height difference between the III-polar and N-polar materials in the lateral polarity configuration generates adequate changes in topography to influence cell growth, improves cell adhesion and promotes cell migration along the direction of the features. As the designed material configuration is further explored for biochemical sensing, the lateral polarity scheme may provide a route in assessing the non-specific protein adsorption to this varying nano-topography that drives the subsequent cell response.
authors.affiliation: UNC/NCSU Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, NC, United States.
authors.forename: L E
authors.initials: LE
authors.lastname: Bain
authors.affiliation: Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, United States.
authors.forename: R
authors.initials: R
authors.lastname: Kirste
authors.affiliation: Department of Molecular Biomedical Sciences, Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, United States.
authors.forename: C A
authors.initials: CA
authors.lastname: Johnson
authors.affiliation: Department of Molecular Biomedical Sciences, Center for Comparative Medicine and Translational Research, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, United States.
authors.forename: H T
authors.initials: HT
authors.lastname: Ghashghaei
authors.affiliation: Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, United States.
authors.forename: R
authors.initials: R
authors.lastname: Collazo
authors.affiliation: Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, United States. Electronic address: Ivanisevic@ncsu.edu.
authors.forename: A
authors.initials: A
authors.lastname: Ivanisevic
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry* / Q000494:pharmacology; D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects; D005708:Gallium / Q000737:chemistry* / Q000494:pharmacology; D009474:Neurons / Q000166:cytology* / Q000187:drug effects*; D016716:PC12 Cells; D051381:Rats; D012666:Semiconductors
chemical_list: D017607:Aluminum Compounds; C513700:aluminum gallium nitride; D005708:Gallium
keywords: Cell adhesion; Gallium nitride; Neurons; Polarity; Semiconductor