p53 is a tumor-suppressor protein related to the cell cycle and programmed cell apoptosis. Herein, dual-targeting nanovesicles are designed for in situ imaging of intracellular wild-type p53 (WTp53) and mutant p53 (MUp53). Nanovesicle-encapsulated plasmonic gold nanoparticles (AuNPs) were functionalized with consensus DNA duplexes, and a fluorescein isothiocyanate (FITC)-marked anti-MUp53 antibody was conjugated to the nanovesicle surface. After entering the cytoplasm, the released AuNPs aggregated through recognition of WTp53 and the double-stranded DNA. The color changes of AuNPs were observed using dark-field microscopy, which showed the intracellular WTp53 distribution. The MUp53 location was detected though the immunological recognition between FITC-labeled anti-MUp53 and MUp53. Thus, a one-step incubation method for the in situ imaging of intracellular WTp53 and MUp53 was obtained; this was used to monitor the p53 level under a drug treatment.

p53 is a tumor-suppressor protein related to the cell cycle and programmed cell apoptosis. Herein, dual-targeting nanovesicles are designed for in situ imaging of intracellular wild-type p53 (WTp53) and mutant p53 (MUp53). Nanovesicle-encapsulated plasmonic gold nanoparticles (AuNPs) were functionalized with consensus DNA duplexes, and a fluorescein isothiocyanate (FITC)-marked anti-MUp53 antibody was conjugated to the nanovesicle surface. After entering the cytoplasm, the released AuNPs aggregated through recognition of WTp53 and the double-stranded DNA. The color changes of AuNPs were observed using dark-field microscopy, which showed the intracellular WTp53 distribution. The MUp53 location was detected though the immunological recognition between FITC-labeled anti-MUp53 and MUp53. Thus, a one-step incubation method for the in situ imaging of intracellular WTp53 and MUp53 was obtained; this was used to monitor the p53 level under a drug treatment.

Hydrogen sulfide (H₂S) has emerged as an important gasotransmitter in diverse physiological processes, although many aspects of its roles remain unclear, partly owing to a lack of robust analytical methods. Herein we report a novel surface-enhanced Raman scattering (SERS) nanosensor, 4-acetamidobenzenesulfonyl azide-functionalized gold nanoparticles (AuNPs/4-AA), for detecting the endogenous H₂S in living cells. The detection is accomplished with SERS spectrum changes of AuNPs/4-AA resulting from the reaction of H₂S with 4-AA on AuNPs. The SERS nanosensor exhibits high selectivity toward H₂S. Furthermore, AuNPs/4-AA responds to H₂S within 1 min with a 0.1 μM level of sensitivity. In particular, our SERS method can be utilized to monitor the endogenous H₂S generated in living glioma cells, demonstrating its great promise in studies of pathophysiological pathways involving H₂S.

Hydrogen sulfide (H₂S) has emerged as an important gasotransmitter in diverse physiological processes, although many aspects of its roles remain unclear, partly owing to a lack of robust analytical methods. Herein we report a novel surface-enhanced Raman scattering (SERS) nanosensor, 4-acetamidobenzenesulfonyl azide-functionalized gold nanoparticles (AuNPs/4-AA), for detecting the endogenous H₂S in living cells. The detection is accomplished with SERS spectrum changes of AuNPs/4-AA resulting from the reaction of H₂S with 4-AA on AuNPs. The SERS nanosensor exhibits high selectivity toward H₂S. Furthermore, AuNPs/4-AA responds to H₂S within 1 min with a 0.1 μM level of sensitivity. In particular, our SERS method can be utilized to monitor the endogenous H₂S generated in living glioma cells, demonstrating its great promise in studies of pathophysiological pathways involving H₂S.

Nanoporentechniken, die die Funktionen natürlicher Ionenkanäle nachahmen, sind nützliche Methoden für den Einzelmolekülnachweis. Das Verfahren erlaubt die selektive Analyse von Nukleinsäuren in Echtzeit und im Hochdurchsatz. Zwei Arten von Nanoporen finden Anwendung: biologische Nanoporen und Festkörpernanoporen. Dieser Kurzaufsatz beleuchtet die Grundlagen und jüngsten Fortschritte bei der nanoporenbasierten Sequenzierung und Detektion von Nukleinsäuren. Außerdem wird eine neuartige, erst kürzlich eingeführte Nanoporentechnik für die Analyse von Biomolekülen vorgestellt.

Nanopore-based techniques, which mimic the functions of natural ion channels, have attracted increasing attention as unique methods for single-molecule detection. The technology allows the real-time, selective, high-throughput analysis of nucleic acids through both biological and solid-state nanopores. In this Minireview, the background and latest progress in nanopore-based sequencing and detection of nucleic acids are summarized, and light is shed on a novel platform for nanopore-based detection.

Quantum dots (QDs) have been widely used for fluorescent imaging in cells. In particular, surface functionalized QDs are of interest, since they possess the ability to recognize and detect the analytes in the surrounding nanoscale environment based on electron and hole transfer between the analytes and the QDs. Here we demonstrate that fluorescence enhancement/quenching in QDs can be switched by electrochemically modulating electron transfer between attached molecules and QDs. For this purpose, a number of redox-active coenzyme Q (CoQ) disulfide derivatives [CoQC_nS]₂ were synthesized with different alkyl chain lengths (n=1, 5, and 10). The system supremely sensitive to NADH (nicotinamide adenine dinucleotide) and superoxide radical (O₂^.−), and represents a biomimetic electron-transfer system, modeling part of the mitochondrial respiratory chain. The results of our in situ fluorescence spectroelectrochemical study demonstrate that the reduced state of [CoQC_nS]₂ significantly enhanced the fluorescence intensity of CdTe/ZnS QDs, while the oxidized state of the CoQ conjugates quench the fluorescence to varying degrees. Fluorescence imaging of cells loaded with the conjugate QD-[CoQC_nS]₂ displayed strikingly differences in the fluorescence depending on the redox state of the capping layer, thus introducing a handle for evaluating the status of the cellular redox potential status. Moreover, an MTT assay (MTT=3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) proved that the cytotoxicity of QDs was significantly reduced after immobilization by CoQ derivatives. Those unique features make CoQ derivatived QDs as a promising probe to image redox coenzyme function in vitro and in vivo.

A methylene-bridged bis-coenzyme Q₀, bis(2,3-dimethoxy-5-methyl-l,4-benzoquinone)methane (Bis-CoQ₀), that shows intramolecular electronic communications has been synthesized for the first time. By employing electrochemical, in situ UV/Vis, and electron paramagnetic resonance (EPR) spectroelectrochemical techniques, the unstable reduced intermediate species—monoradicals, diamagnetic dianions and tetraanions of Bis-CoQ₀—have been observed. The electron-transfer process can be defined as a three-step reduction process with a total of four electrons in solution in CH₃CN. The chemical reaction in the third redox step process was confirmed by variable temperature cyclic voltammetry. In an aprotic CH₃CN solution, the peak potential separation between electron-transfer steps diminished sequentially with increasing concentration of water. The hydrogen-bonding interactions between water and the electrochemically reduced intermediates of Bis-CoQ₀ can be estimated by peak potential shifts. The electronic communications of Bis-CoQ₀ may have been blocked when one reduction peak was observed with proper quantities of water in CH₃CN solution. The antioxidant defense capacity of Bis-CoQ₀-protected cells has also been assessed.

As a unique technique at the singe-molecule level to explore the distribution and temporal order of events, nanopore technology has attracted increasing attention. In comparison to the previous applications in DNA sequencing, this Focus Review highlights the technical details of biological nanopores, especially α-hemolysin, in the analysis of peptides and proteins. The instrument configurations, experimental interferences, and data analysis including the conformation of peptides and proteins and their interactions for single-molecule detection are discussed.