title: Spectrally matched upconverting luminescent nanoparticles for monitoring enzymatic reactions.
abstract: We report on upconverting luminescent nanoparticles (UCLNPs) that are spectrally tuned such that their emission matches the absorption bands of the two most important species associated with enzymatic redox reactions. The core-shell UCLNPs consist of a β-NaYF4 core doped with Yb(3+)/Tm(3+) ions and a shell of pure β-NaYF4. Upon 980 nm excitation, they display emission bands peaking at 360 and 475 nm, which is a perfect match to the absorption bands of the enzyme cosubstrate NADH and the coenzyme FAD, respectively. By exploiting these spectral overlaps, we have designed fluorescent detection schemes for NADH and FAD that are based on the modulation of the emission intensities of UCLNPs by FAD and NADH via an inner filter effect.
authors.affiliation: Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg , 93040 Regensburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Wilhelm
authors.forename: Melisa
authors.initials: M
authors.lastname: del Barrio
authors.forename: Josef
authors.initials: J
authors.lastname: Heiland
authors.forename: Sandy F
authors.initials: SF
authors.lastname: Himmelstoß
authors.forename: Javier
authors.initials: J
authors.lastname: Galbán
authors.forename: Otto S
authors.initials: OS
authors.lastname: Wolfbeis
authors.forename: Thomas
authors.initials: T
authors.lastname: Hirsch
mesh_terms: D004798:Enzymes / Q000378:metabolism*; D000431:Ethanol / Q000032:analysis; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D005947:Glucose / Q000032:analysis; D057927:Hydrophobic and Hydrophilic Interactions; D049449:Luminescence; D009243:NAD / Q000378:metabolism; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D013057:Spectrum Analysis; D013499:Surface Properties; D014961:X-Ray Diffraction; D015019:Yttrium / Q000737:chemistry
chemical_list: D004798:Enzymes; D009243:NAD; D005182:Flavin-Adenine Dinucleotide; D000431:Ethanol; D015019:Yttrium; D005947:Glucose
keywords: core−shell nanoparticles; enzymatic reactions; inner filter effect; upconversion; upconverting nanoparticles