title: Live-cell imaging of biothiols via thiol/disulfide exchange to trigger the photoinduced electron transfer of gold-nanodot sensor.
abstract: Biothiols have been reported to involve in intracellular redox-homeostasis against oxidative stress. In this study, a highly selective and sensitive fluorescent probe for sensing biothiols is explored by using an ultrasmall gold nanodot (AuND), the dendrimer-entrapped Au8-cluster. This strategy relies upon a thiol/disulfide exchange to trigger the fluorescence change through a photoinduced electron transfer (PET) process between the Au8-cluster (as an electron donor) and 2-pyridinethiol (2-PyT) (as an electron acceptor) for sensing biothiols. When 2-PyT is released via the cleavage of disulfide bonds by biothiols, the PET process from the Au8-cluster to 2-PyT is initiated, resulting in fluorescence quenching. The fluorescence intensity was found to decrease linearly with glutathione (GSH) concentration (0-1500μM) at physiological relevant levels and the limit of detection for GSH was 15.4μM. Compared to most nanoparticle-based fluorescent probes that are limited to detect low molecular weight thiols (LMWTs; i.e., GSH and cysteine), the ultrasmall Au8-cluster-based probe exhibited less steric hindrance and can be directly applied in selectively and sensitively detecting both LMWTs and high molecular weight thiols (HMWTs; i.e., protein thiols). Based on such sensing platform, the surface-functionalized Au8-cluster has significant promise for use as an efficient nanoprobe for intracellular fluorescence imaging of biothiols including protein thiols in living cells whereas other nanoparticle-based fluorescent probes cannot.
authors.affiliation: Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli 35053, Taiwan.
authors.forename: Ching-Ping
authors.initials: CP
authors.lastname: Liu
authors.affiliation: Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli 35053, Taiwan.
authors.forename: Te-Haw
authors.initials: TH
authors.lastname: Wu
authors.affiliation: Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli 35053, Taiwan.
authors.forename: Chia-Yeh
authors.initials: CY
authors.lastname: Liu
authors.affiliation: Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli 35053, Taiwan. Electronic address: shuyi@nhri.org.tw.
authors.forename: Shu-Yi
authors.initials: SY
authors.lastname: Lin
mesh_terms: D002460:Cell Line; D050091:Dendrimers / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry*; D004579:Electron Transport; D005456:Fluorescent Dyes / Q000737:chemistry*; D005978:Glutathione / Q000032:analysis*; D006046:Gold / Q000737:chemistry*; D006801:Humans; D049329:Nanostructures / Q000737:chemistry; D061848:Optical Imaging / Q000379:methods*; D011506:Proteins / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000032:analysis*
chemical_list: D050091:Dendrimers; D004220:Disulfides; D005456:Fluorescent Dyes; C104700:PAMAM Starburst; D011506:Proteins; D013438:Sulfhydryl Compounds; D006046:Gold; D005978:Glutathione
keywords: Gold nanodots; Intracellular fluorescent probe; Ligand exchange; Photoinduced electron transfer; Protein thiols