title: Reversible plasmonic probe sensitive for pH in micro/nanospaces based on i-motif-modulated morpholino-gold nanoparticle assembly.
abstract: Exploring local pH in micro/nanoscale is fundamentally important for understanding microprocesses including the corrosion of metal and the metabolism of cell. Regular fluorescence pH probes and potentiometric electrodes show either low signal intensity or lack of spatial resolution when being applied in a micro/nanoenvironment. Here, we developed a nanoscale reversible pH probe based on the plasmonic coupling effect of i-motif modulated gold nanoparticle (AuNP) assembly. The pH probe shows a reversible and highly sensitive response to pH variation between 4.5 and 7.5. Introduction of morpholino oligomers (MO), a neutral analog of DNA, into the assembly endows the pH probe with high stability even under low salt concentration. The intense optical signal of a AuNP enables local pH to be read out not only in the micro/nanofluidic channel but also on a single i-motif-MO-AuNP assembly. Recording of the strong plasmonic resonance scattering spectrum of AuNP provides a promising method for extracting chemical information in nanospace of biological systems.
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhao
authors.forename: Lei
authors.initials: L
authors.lastname: Cao
authors.forename: Jun
authors.initials: J
authors.lastname: Ouyang
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.forename: Kang
authors.initials: K
authors.lastname: Wang
authors.forename: Xing-Hua
authors.initials: XH
authors.lastname: Xia
mesh_terms: D004566:Electrodes; D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry*; D060172:Morpholinos / Q000737:chemistry*; D036103:Nanotechnology
chemical_list: D060172:Morpholinos; D006046:Gold