title: Formation of fluorescent polydopamine dots from hydroxyl radical-induced degradation of polydopamine nanoparticles.
abstract: This study describes the synthesis of fluorescent polydopamine dots (PDs) through hydroxyl radical-induced degradation of polydopamine nanoparticles. The decomposition of polydopamine nanoparticles to fluorescent PDs was confirmed using transmission electron microscopy and dark-field microscopy. The analysis of PDs by using laser desorption/ionization time-of-flight mass spectrometry revealed that the PDs consisted of dopamine, 5,6-dihydroxyindole, and trihydroxyindole units. Oligomerization and self-assembly of these units produced a broad adsorption band, resulting in an excitation-wavelength-dependent emission behavior. The maximal fluorescence of PDs appeared at 440 nm with a quantum yield of 1.2%. The coordination between the catechol groups of PDs and ferric ions (Fe(3+)) quenched the fluorescence of PDs; the limit of detection at a signal-to-noise ratio of 3 for Fe(3+) was determined to be 0.3 μM. The presence of pyrophosphate switched on the fluorescence of the PD-Fe(3+) complexes. Compared to the other reported methods for sensing Fe(3+), PDs provided simple, low-cost, and reusable detection of Fe(3+).
authors.affiliation: Department of Chemistry, National Sun Yat-sen University, Kaohsiung, Taiwan. tsengwl@mail.nsysu.edu.tw.
authors.forename: Jia-Hui
authors.initials: JH
authors.lastname: Lin
authors.forename: Cheng-Ju
authors.initials: CJ
authors.lastname: Yu
authors.forename: Ya-Chun
authors.initials: YC
authors.lastname: Yang
authors.forename: Wei-Lung
authors.initials: WL
authors.lastname: Tseng
mesh_terms: D004579:Electron Transport; D005290:Ferric Compounds / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D011108:Polymers / Q000737:chemistry*; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence
chemical_list: D005290:Ferric Compounds; D007211:Indoles; D011108:Polymers; C568283:polydopamine; C010362:trihydroxyindole; D017665:Hydroxyl Radical; C033871:5,6-dihydroxyindole