title: Nanometer depth resolution in 3D topographic analysis of drug-loaded nanofibrous mats without sample preparation.
abstract: We showed that scanning white light interferometry (SWLI) can provide nanometer depth resolution in 3D topographic analysis of electrospun drug-loaded nanofibrous mats without sample preparation. The method permits rapidly investigating geometric properties (e.g. fiber diameter, orientation and morphology) and surface topography of drug-loaded nanofibers and nanomats. Electrospun nanofibers of a model drug, piroxicam (PRX), and hydroxypropyl methylcellulose (HPMC) were imaged. Scanning electron microscopy (SEM) served as a reference method. SWLI 3D images featuring 29 nm by 29 nm active pixel size were obtained of a 55 μm × 40 μm area. The thickness of the drug-loaded non-woven nanomats was uniform, ranging from 2.0 μm to 3.0 μm (SWLI), and independent of the ratio between HPMC and PRX. The average diameters (n=100, SEM) for drug-loaded nanofibers were 387 ± 125 nm (HPMC and PRX 1:1), 407 ± 144 nm (HPMC and PRX 1:2), and 290 ± 100 nm (HPMC and PRX 1:4). We found advantages and limitations in both techniques. SWLI permits rapid non-contacting and non-destructive characterization of layer orientation, layer thickness, porosity, and surface morphology of electrospun drug-loaded nanofibers and nanomats. Such analysis is important because the surface topography affects the performance of nanomats in pharmaceutical and biomedical applications.
authors.affiliation: Department of Pharmacy, Faculty of Medicine, University of Tartu, Nooruse 1, 50411 Tartu, Estonia. Electronic address: urve.paaver@ut.ee.
authors.forename: Urve
authors.initials: U
authors.lastname: Paaver
authors.affiliation: Department of Pharmacy, Faculty of Medicine, University of Tartu, Nooruse 1, 50411 Tartu, Estonia. Electronic address: jyrki.heinamaki@ut.ee.
authors.forename: Jyrki
authors.initials: J
authors.lastname: Heinämäki
authors.affiliation: Helsinki Institute of Physics, P.O. Box 64 (Gustaf Hällströmin katu 2a), University of Helsinki, FI-00014, Finland. Electronic address: ivan.kassamakov@helsinki.fi.
authors.forename: Ivan
authors.initials: I
authors.lastname: Kassamakov
authors.affiliation: Electronics Laboratory, Department of Physics, P.O. Box 64 (Gustaf Hällströmin katu 2a), University of Helsinki, FI-00014, Finland. Electronic address: haeggstr@mappi.helsinki.fi.
authors.forename: Edward
authors.initials: E
authors.lastname: Hæggström
authors.affiliation: Electronics Laboratory, Department of Physics, P.O. Box 64 (Gustaf Hällströmin katu 2a), University of Helsinki, FI-00014, Finland. Electronic address: tuomo.ylitalo@helsinki.fi.
authors.forename: Tuomo
authors.initials: T
authors.lastname: Ylitalo
authors.affiliation: Electronics Laboratory, Department of Physics, P.O. Box 64 (Gustaf Hällströmin katu 2a), University of Helsinki, FI-00014, Finland. Electronic address: anton.nolvi@helsinki.fi.
authors.forename: Anton
authors.initials: A
authors.lastname: Nolvi
authors.affiliation: Institute of Physics, University of Tartu, Riia 142, 51014 Tartu, Estonia. Electronic address: jekaterina.kozlova@ut.ee.
authors.forename: Jekaterina
authors.initials: J
authors.lastname: Kozlova
authors.affiliation: Department of Pharmacy, Faculty of Medicine, University of Tartu, Nooruse 1, 50411 Tartu, Estonia. Electronic address: ivo.laidmae@ut.ee.
authors.forename: Ivo
authors.initials: I
authors.lastname: Laidmäe
authors.affiliation: Department of Pharmacy, Faculty of Medicine, University of Tartu, Nooruse 1, 50411 Tartu, Estonia. Electronic address: karin.kogermann@ut.ee.
authors.forename: Karin
authors.initials: K
authors.lastname: Kogermann
authors.affiliation: Department of Pharmacy, Faculty of Medicine, University of Tartu, Nooruse 1, 50411 Tartu, Estonia. Electronic address: peep.veski@ut.ee.
authors.forename: Peep
authors.initials: P
authors.lastname: Veski
mesh_terms: D055664:Electrochemical Techniques; D065347:Hypromellose Derivatives; D021621:Imaging, Three-Dimensional; D007368:Interferometry / Q000379:methods*; D008747:Methylcellulose / Q000031:analogs & derivatives / Q000737:chemistry; D008855:Microscopy, Electron, Scanning / Q000379:methods; D057139:Nanofibers; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D010894:Piroxicam / Q000008:administration & dosage* / Q000737:chemistry; D016062:Porosity; D013499:Surface Properties
chemical_list: D010894:Piroxicam; D065347:Hypromellose Derivatives; D008747:Methylcellulose
keywords: Electrospinning; Nanofibers; Piroxicam; Scanning electron microscopy (SEM); Scanning white light interferometry (SWLI); Surface topography analysis