title: Electrochemical, photoelectrochemical, and piezoelectric analysis of tyrosinase activity by functionalized nanoparticles.
abstract: The electrochemical and photoelectrochemical detection of tyrosinase (TR) activity (an indicative marker for melanoma cancer cells) is reported, using Pt nanoparticles (NPs) or CdS NPs as electrocatalytic labels or photoelectrochemical reporter units. The Pt NPs or CdS NPs are modified with a tyrosine methyl ester, (1), capping layer. Oxidation of the capping layer by TR/O2 yields the respective L-DOPA and dopaquinone products. The reduction of the resulting mixture of products with citric acid yields the L-DOPA derivative,(3), as a single product. The association of the (3)-functionalized Pt NPs or CdS NPs to a boronic acid monolayer-modified electrode enables the electrochemical transduction of TR activity by the Pt-NPs-electrocatalyzed reduction of H2O2 or the photoelectrochemical transduction of TR activity by the generation of photocurrents in the presence of triethanolamine as a sacrificial electron donor. The detection limits for analyzing TR corresponds to 1 U and 0.1 U by the electrochemical and photoelectrochemical methods, respectively. The association of the Pt NPs or CdS NPs to the functionalized monolayer electrode is followed by quartz crystal microbalance measurements.
authors.affiliation: Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Huseyin Bekir
authors.initials: HB
authors.lastname: Yildiz
authors.forename: Ronit
authors.initials: R
authors.lastname: Freeman
authors.forename: Ron
authors.initials: R
authors.lastname: Gill
authors.forename: Itamar
authors.initials: I
authors.lastname: Willner
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods*; D053768:Metal Nanoparticles / Q000737:chemistry*; D014442:Monophenol Monooxygenase / Q000032:analysis* / Q000378:metabolism; D010777:Photochemistry; D010984:Platinum / Q000737:chemistry; D013440:Sulfides / Q000737:chemistry; D014443:Tyrosine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism
chemical_list: D019187:Cadmium Compounds; D013440:Sulfides; C034939:cadmium sulfide; C040444:tyrosine methyl ester; D014443:Tyrosine; D010984:Platinum; D014442:Monophenol Monooxygenase