title: Ultrasensitive detection of toxic cations through changes in the tunnelling current across films of striped nanoparticles.
abstract: Although multiple methods have been developed to detect metal cations, only a few offer sensitivities below 1 pM, and many require complicated procedures and sophisticated equipment. Here, we describe a class of simple solid-state sensors for the ultrasensitive detection of heavy-metal cations (notably, an unprecedented attomolar limit for the detection of CH(3)Hg(+) in both standardized solutions and environmental samples) through changes in the tunnelling current across films of nanoparticles (NPs) protected with striped monolayers of organic ligands. The sensors are also highly selective because of the ligand-shell organization of the NPs. On binding of metal cations, the electronic structure of the molecular bridges between proximal NPs changes, the tunnelling current increases and highly conductive paths ultimately percolate the entire film. The nanoscale heterogeneity of the structure of the film broadens the range of the cation-binding constants, which leads to wide sensitivity ranges (remarkably, over 18 orders of magnitude in CH(3)Hg(+) concentration).
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Eun Seon
authors.initials: ES
authors.lastname: Cho
authors.forename: Jiwon
authors.initials: J
authors.lastname: Kim
authors.forename: Baudilio
authors.initials: B
authors.lastname: Tejerina
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Hermans
authors.forename: Hao
authors.initials: H
authors.lastname: Jiang
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Nakanishi
authors.forename: Miao
authors.initials: M
authors.lastname: Yu
authors.forename: Alexander Z
authors.initials: AZ
authors.lastname: Patashinski
authors.forename: Sharon C
authors.initials: SC
authors.lastname: Glotzer
authors.forename: Francesco
authors.initials: F
authors.lastname: Stellacci
authors.forename: Bartosz A
authors.initials: BA
authors.lastname: Grzybowski
mesh_terms: D004563:Electrochemistry / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis* / Q000737:chemistry*; D019855:Ethylene Glycol / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D019216:Metals, Heavy / Q000032:analysis* / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D004785:Environmental Pollutants; D019216:Metals, Heavy; D013438:Sulfhydryl Compounds; D006046:Gold; D019855:Ethylene Glycol