The inside walls of a nanopipette tip are decorated by a Pt deposit that is used as an open bipolar electrochemiluminescence (ECL) device to achieve intracellular wireless electroanalysis. The ...synergetic actions of nanopipette and of bipolar ECL lead to the spatial confinement of the voltage drop at the level of the Pt deposit, which generates ECL emission from luminol. The porous structure of Pt deposit permits the electrochemical transport of intracellular molecules into the nanopipette that is coupled with enzymatic reactions. Thus, the intracellular concentrations of hydrogen peroxide or glucose are measured in vivo as well as the intracellular sphingomyelinase activity. In comparison with the classic bipolar ECL, the remarkably low potential applied in our approach is restricted inside the nanopipette and it minimizes the potential bias of the voltage on the cellular activity. Accordingly, this wireless ECL approach provides a new direction for analysis of single living cells.
A nanopipette tip decorated with a Pt deposit is used as an open bipolar electrochemiluminescence device to achieve intracellular wireless electroanalysis. The porous structure of the Pt deposit permits electrochemical transport of intracellular molecules into the nanopipette. Intracellular concentrations of H2O2 or glucose are measured in vivo as well as the intracellular sphingomyelinase activity.
The evolution of photoelectrochemical (PEC) bioanalysis has resulted in substantial progress in its analytical performance and biodetection applications. The aim of this review is to provide a ...panoramic snapshot of the state of the art in this dynamically developing field, with special emphasis on PEC DNA analysis, immunoassay, enzymatic biosensing and cell-related detection. The future prospects in this area are also evaluated and discussed. This work will serve as a useful source to inform the interested audience of the latest developments and applications in the field of PEC bioanalysis.
This review provides a panoramic snapshot of the state of the art in the dynamically developing field of photoelectrochemical bioanalysis.
Electrogenerated chemiluminescence, also known as electrochemiluminescence (ECL), is an electrochemically induced production of light by excited luminophores generated during redox reactions. It can ...be used to sense the charge transfer and related processes at electrodes
via
a simple visual readout; hence, ECL is an outstanding tool in analytical sensing. The traditional ECL approach measures averaged electrochemical quantities of a large ensemble of individual entities, including molecules, microstructures and ions. However, as a real system is usually heterogeneous, the study of single entities holds great potential in elucidating new truths of nature which are averaged out in ensemble assays or hidden in complex systems. We would like to review the development of ECL intensity and imaging based single entity detection and place emphasis on the assays of small entities including single molecules, micro/nanoparticles and cells. The current challenges for and perspectives on ECL detection of single entities are also discussed.
We summarize the history and recent development that has been made in the ECL detection of single entities.
Photoelectrochemical DNA Biosensors Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan
Chemical reviews,
08/2014, Letnik:
114, Številka:
15
Journal Article
Recenzirano
Zhao et al explore photoelectrochemical (PEC) DNA biosensors, focusing on topics such as transducers, probe immobilization, DNA interactions, and PEC transduction of DNA interactions.
Better than expected: With a regular boronic acid as the functional monomer, a general and facile approach for glycoprotein imprinting exhibited several highly favorable features that are beyond ...normal expectation, which make the prepared MIPs feasible for the recognition of trace glycoproteins in complicated real samples.
Electrochemiluminescence (ECL)-based capacitance microscopy using a square-wave voltage is established unprecedentedly to realize the label-free visualization of species on electrode surfaces and ...cellular plasma membranes. The drop in the local capacitance upon the binding of species to the surface or to a cellular membrane is derived to induce a relatively larger potential drop (V dl) across the double layer on the local electrode surface, which is utilized to prompt enhanced ECL at the binding position. The square-wave voltage with a frequency of as high as 1.5 kHz is proven to be favorable for the discrimination of the local ECL from the surrounding signal. Using this new detection principle and resultant capacitance microscopy, carcinoembryonic antigens (CEA) at amounts of as low as 1 pg can be visualized. Further application of this approach permits the direct imaging of CEA antigens on single MCF-7 cells through the capacitance change after the formation of the antigen–antibody complex. Successful visualization of the analyte without any ECL tag will allow not only special capacitance microscopy for label-free bioassays but also a novel ECL detection approach for the sensitive detection of biomolecules.
Pretargeted imaging has emerged as a promising approach to advance nuclear imaging of malignant tumors. Herein, we combine the enzyme‐mediated fluorogenic reaction and in situ self‐assembly with the ...inverse electron demand Diels–Alder (IEDDA) reaction to develop an activatable pretargeted strategy for multimodality imaging. The trans‐cyclooctene (TCO) bearing small‐molecule probe, P‐FFGd‐TCO, can be activated by alkaline phosphatase and in situ self‐assembles into nanoaggregates (FMNPs‐TCO) retained on the membranes, permitting to (1) amplify near‐infrared (NIR) fluorescence (FL) and magnetic resonance imaging (MRI) signals, and (2) enrich TCOs to promote IEDDA ligation. The Gallium‐68 (68Ga) labeled tetrazine can readily conjugate the tumor‐retained FMNPs‐TCO to enhance radioactivity uptake in tumors. Strong NIR FL, MRI, and positron emission tomography (PET) signals are concomitantly achieved, allowing for pretargeted multimodality imaging of ALP activity in HeLa tumor‐bearing mice.
A pretargeted multimodality imaging strategy is based on a combination of the enzyme‐mediated fluorogenic reaction and in situ self‐assembly with the IEDDA reaction. A trans‐cyclooctene (TCO) bearing a small‐molecule probe is first activated by the target enzyme, leading to in situ self‐assembly and enrichment of the TCOs. This allows subsequent labelling of radioisotopes via the IEDDA reaction, providing NIR FL, MRI and PET signals for in vivo imaging.
Wu et al explore electrochemically generated versus photoexcited luminescence from semiconductor nanomaterials. They focus on the fundamentals of the electrochemical luminescence and photoexcited ...luminescence, as well as their analytical applications.
Stimuli‐responsive smart photosensitizer (PS) nanoassemblies that allow enhanced delivery and controlled release of PSs are promising for imaging‐guided photodynamic therapy (PDT) of tumors. However, ...the lack of high‐sensitivity and spatial‐resolution signals and fast washout of released PSs from tumor tissues have impeded PDT efficacy in vivo. Herein, we report tumor targeting, redox‐responsive magnetic and fluorogenic PS nanoassemblies (NP‐RGD) synthesized via self‐assembly of a cRGD‐ and disulfide‐containing fluorogenic and paramagnetic small molecule (1‐RGD) for fluorescence/magnetic resonance bimodal imaging‐guided tumor PDT. NP‐RGD show high r1 relaxivity but quenched fluorescence and PDT activity; disulfide reduction by glutathione (GSH) promotes efficient disassembly into a small‐molecule probe (2‐RGD) and an organic PS (PPa‐SH), which could further bind with intracellular albumin, allowing prolonged retention and cascade activation of fluorescence and PDT to ablate tumors.
Magnetic and fluorogenic photosensitizer nanoassemblies (NP‐RGD) were constructed via self‐assembly of a cRGD‐ and disulfide‐containing small molecule (1‐RGD). The nanoassemblies allowed the cascade activation of fluorescence/magnetic resonance bimodal imaging and on‐demand photodynamic therapy in the tumor through redox‐driven disassembly and in situ binding with albumin.
Single‐cell analysis techniques are essential for understanding the microheterogeneity and functions of cells. Low‐copy‐number proteins play important roles in cell functioning, but their measurement ...in single cells remains challenging. Herein, we report an approach, called plasmonic immunosandwich assay (PISA), for probing low‐copy‐number proteins in single cells. This approach combined in vivo immunoaffinity extraction and plasmon‐enhanced Raman scattering (PERS). Target proteins were specifically extracted from the cells by microprobes modified with monoclonal antibody or molecularly‐imprinted polymer (MIP), followed by labeling with Raman‐active nanotags. The PERS detection, with Raman intensity enhanced by 9 orders of magnitude, provided ultrasensitive detection at the single‐molecule level. Using this approach, we found that alkaline phosphatase and survivin were expressed in distinct levels in cancer and normal cells, and that extended culture passage resulted in reduced expression of survivin. We further developed acupuncture needle‐based PISA for probing low‐copy‐number proteins in living bodies.
Plasmonic immunosandwich assay (PISA) was developed for probing low‐copy‐number proteins in single cells. PISA combined in vivo immunoaffinity extraction and plasmon‐enhanced Raman scattering (PERS). Target proteins were extracted from the cells by microprobes modified with monoclonal antibodies or molecularly imprinted polymers, followed by labeling with Raman‐active nanotags.
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