title: Release of polyphenolic drugs from dynamically bonded layer-by-layer films.
abstract: Layer-by-layer (LbL) assembled films have been exploited for surface-mediated drug delivery. The drugs loaded in the films were usually released via diffusion or the degradation of one of the film components. Here we demonstrate that drug release can also be achieved by exploiting the dynamic nature of hydrogen-bonded LbL films. The films were fabricated from tannic acid (TA), a model polyphenolic drug, and poly(vinyl pyrrolidone) (PVPON). The driving force for the film buildup is the hydrogen bonding between the two components, which was confirmed by Fourier transform infrared (FTIR) spectra. The film growth is linear, and the growth rate of the film decreases with increasing assembly temperature. Because of the reversible/dynamic nature of hydrogen bonding, when soaked in aqueous solutions, the PVPON/TA films disassemble gradually and thus release TA to the media. The release rate of TA increases with increasing pH and temperature but decreases with increasing ionic strength. Scanning electron microscopy (SEM) studies on the surface morphology of the film during TA release reveal that the film surface becomes smoother and then rougher again because of the dewetting of the film. The released TA can scavenge ABTS(+•) cation radicals, indicating it retains its antioxidant activity, a major biological activity of polyphenols.
authors.affiliation: State Key Laboratory of Medicinal Chemical Biology and Key Laboratory of Functional Polymer Materials, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhou
authors.forename: Mao
authors.initials: M
authors.lastname: Chen
authors.forename: Lili
authors.initials: L
authors.lastname: Tian
authors.forename: Ying
authors.initials: Y
authors.lastname: Guan
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D052160:Benzothiazoles / Q000737:chemistry; D016503:Drug Delivery Systems / Q000379:methods*; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D059808:Polyphenols / Q000737:chemistry*; D011205:Povidone / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013451:Sulfonic Acids / Q000737:chemistry; D013634:Tannins / Q000737:chemistry
chemical_list: D000975:Antioxidants; D052160:Benzothiazoles; D059808:Polyphenols; D013451:Sulfonic Acids; D013634:Tannins; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D011205:Povidone