title: Direct isolation of flavonoids from plants using ultra-small anatase TiO₂ nanoparticles.
abstract: Surface functionalization of nanoparticles has become an important tool for in vivo delivery of bioactive agents to their target sites. Here we describe the reverse strategy, nanoharvesting, in which nanoparticles are used as a tool to isolate bioactive compounds from living cells. Anatase TiO₂ nanoparticles smaller than 20 nm form strong bonds with molecules bearing enediol and especially catechol groups. We show that these nanoparticles enter plant cells, conjugate enediol and catechol group-rich flavonoids in situ, and exit plant cells as flavonoid-nanoparticle conjugates. The source plant tissues remain viable after treatment. As predicted by the surface chemistry of anatase TiO₂ nanoparticles, quercetin-based flavonoids were enriched amongst the nanoharvested flavonoid species. Nanoharvesting eliminates the use of organic solvents, allows spectral identification of the isolated compounds, and opens new avenues for use of nanomaterials for coupled isolation and testing of bioactive properties of plant-synthesized compounds.
authors.affiliation: Plant Physiology, Biochemistry and Molecular Biology Program, Department of Plant and Soil Sciences, College of Agriculture, University of Kentucky, Lexington, KY, 40546, USA.
authors.forename: Jasmina
authors.initials: J
authors.lastname: Kurepa
authors.forename: Ryo
authors.initials: R
authors.lastname: Nakabayashi
authors.forename: Tatjana
authors.initials: T
authors.lastname: Paunesku
authors.forename: Makoto
authors.initials: M
authors.lastname: Suzuki
authors.forename: Kazuki
authors.initials: K
authors.lastname: Saito
authors.forename: Gayle E
authors.initials: GE
authors.lastname: Woloschak
authors.forename: Jan A
authors.initials: JA
authors.lastname: Smalle
mesh_terms: D000872:Anthocyanins / Q000737:chemistry / Q000302:isolation & purification; D017360:Arabidopsis / Q000737:chemistry*; D002396:Catechols / Q000737:chemistry / Q000302:isolation & purification; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification*; D053758:Nanoparticles; D010766:Phosphorylation; D011794:Quercetin / Q000737:chemistry / Q000302:isolation & purification; D014025:Titanium / Q000737:chemistry*
chemical_list: D000872:Anthocyanins; D002396:Catechols; D005419:Flavonoids; C009495:titanium dioxide; D011794:Quercetin; D014025:Titanium; C034221:catechol
keywords: Arabidopsis thaliana; anatase TiO2 nanoparticles; catechols; flavonoids; stress; technical advance