In vivo electrochemistry is one powerful strategy for probing brain chemistry. However, the decreases in sensitivity mainly caused by the adsorption of proteins onto electrode surface in short-term ...in vivo measurements unfortunately render great challenges in both electrode calibration and selectivity against the alternation of proteins. In this study, we observe that the pretreatment of carbon fiber microelectrodes (CFEs) with bovine serum albumin (BSA) would offer a simple but effective strategy to the challenges mentioned above. We verify our strategy for dopamine (DA) with conventionally used CFEs and for ascorbate with our previously developed carbon nanotube-modified CFEs. We find that, in artificial cerebral spinal fluid (aCSF) solution containing BSA, the current responses of the microelectrodes equilibrate shortly and the results for precalibration carried out in this solution are found to be almost the same as those for the postcalibration in pure aCSF. This observation offers a new solution to electrode calibration for in vivo measurements with a technical simplicity. Furthermore, we find that the use of BSA pretreated CFEs to replace bare CFEs would minimize the interference from the alternation of proteins in the brain. This study offers a new general and effective approach to in vivo electrochemistry with a high reliability and a simplified procedure.
Modulation of interfacial electron transfer has been proven to pave a new approach to
in vivo
electrochemical monitoring of brain chemistry; however, designing and establishing highly efficient ...electrocatalytic scheme towards neurochemicals remain a long-standing challenge. Here, we find that recently established single-atom catalyst (SAC) can be used for catalyzing the electro-chemical process of physiologically relevant chemicals and thus offers a new avenue to
in vivo
electrochemical biosensing. To prove this new concept, we used Co single-atom catalyst (Co-SAC), in which the atomic active sites are dispersed in ordered porous N-doping carbon matrix at atomic level, as an example of SACs for analyzing glucose as the physiologically relevant model chemicals. We found that Co-SAC catalyzes the electrochemical oxidation of hydrogen peroxide (H
2
O
2
) at a low potential of ca. +0.05 V (vs. Ag/AgCl). This property was further used for developing an oxidase-based glucose biosensor that was used subsequently as a selective detector of an online electrochemical system (OECS) for continuous monitoring of microdialysate glucose in rat brain. The OECS with Co-SAC-based glucose biosensor as the online detector was well responsive to glucose without interference from other electroactive species in brain microdialysate. This study essentially offers a new approach to
in vivo
electrochemical analysis with SACs as electrocatalysts to modulate interfacial electron transfer.
It is of interest to
in vivo
monitor the co-dynamics of different substances. However, the tracking of multiple species is still challenging. In this work, we demonstrate an
in vivo
electrochemical ...method by using multi-potential step amperometry to
in vivo
detect ascorbic acid (AA) and oxygen (O
2
) simultaneously. In order to achieve good selectivity and high sensitivity for both AA and O
2
, we design a cobalt corrole Co(tpfc)(py)
2
(tpfc = 5,10,15-tris(penta-fluorophenyl) corrole, py = pyridine, denoted as Co-TPFC) and carbon nanotube nanocomposite to modify a carbon fiber microelectrode (Co-TPFC/MWNT/CFE). This Co-TPFC/MWNT/CFE exhibits excellent electrocatalytic properties towards the reduction of O
2
preceding a 4e process and facilitates the oxidation of AA at low potential in the physiological environment. Based on this, we realize simultaneous detection of AA and O
2
using two-potential steps (one cathodic (−0.2 V) and the other anodic (+0.05 V)) with 1 second step time. Both
in vitro
and
in vivo
experiments proved the feasibility of this method. This demonstrated strategy is useful for us to understand various physiological and pathological processes associated with O
2
and AA co-dynamics, and also provides an idea for detecting multiple substances simultaneously.
Simultaneous detection of O
2
and ascorbic acid in the rat brain using a cobalt corrole and carbon nanotube nanocomposite modified carbon fiber electrode.
Nanoscaled electrode has been attracting increasing attention because of striking fundamentals and practical applications. Usually, the nanoscaled electrode is fabricated by manual or photo or ...electron-beam lithography, which is not easy to reproducibly fabricate with simple equipment. In this paper, a cost-effective method, nanoskiving, is developed to fabricate an ultralong nanowire electrode (ULNE). The ULNE is reproducibly obtained by simply sectioning a sandwich epoxy block with a Au film. The width of ULNE could be down to nanometer dependence on the thickness of the Au film, while the length could reach to the millimeter. Thus, the created Au ULNE shows steady-state microamperometric current, characteristic of the nanoelectrode array attributed to its macroscopic length and nanoscaled width without considering the overlap of the diffusion layer of the neighboring nanoelectrode. The electrodeposited Pt/Au ULNE displays unusual electrocatalytic performance toward both the oxidation and reduction of hydrogen peroxide and, as a nanosensor, gives rise to high sensitivity and selectivity of monitoring hydrogen peroxide released from cells stimulated by ascorbic acid.
An ultralow‐limit gas microsensor based on an ultrathin conducting oligoaniline film integrated with microscale gold electrodes is developed. A nanoscale oligoaniline film is fabricated on a ...poly(dimethylsiloxane) (PDMS) substrate using graft polymerization using FeCl3, a mild oxidant, rather than conventional (NH4)2S2O8. The as‐fabricated film is around 14 nm in thickness and above 85% transmittance on a PDMS substrate with a smooth surface morphology and high conductivity. Taking NH3 as a protocol, the nanoscale oligoaniline film microsensor shows an ultralow detection limit to the ppb level with more rapid response and high sensitivity to NH3 compared to the thicker PANI film using conventional methods.
A gas microsensor is developed by integrating an oligoaniline film with microscale gold electrodes. The nanoscale oligoaniline film is fabricated on a poly‐(dimethylsiloxane) substrate using graft polymerization with FeCl3 as a mild oxidant. The as‐fabricated film is around 14‐nm thick and above 85% transmittance on the PDMS substrate. The microsensor shows a ppb level detection limit with rapid response and high sensitivity to NH3 sensing.
This study demonstrates a new electrochemical microbiosensor for selective
in vivo
monitoring of glucose in rat brains. The microbiosensor is prepared by using Prussian blue (PB)/polyaniline ...(PANI)/multi-walled carbon nanotubes (MWNTs) as the electrocatalyst for the reduction and determination of H
2
O
2
generated from the glucose oxidase (GOx)-based enzymatic catalytic reaction. PANI and MWNTs are used to stabilize PB nanoparticles in physiological solutions. As a result, the as-formed three-dimensional (3D) PB/PANI/MWNT nanostructure exhibits a stable and large electrochemical response compared to the PB-modified electrode. The use of PB/PANI/MWNTs in this work to replace "natural peroxidase" (
i.e.
, horseradish peroxidase) used in the existing microbiosensors enables the method developed here to be facile but selective for
in vivo
measurements of glucose virtually interference-free from ascorbic acid and other electroactive species coexisting in the brain. This property, along with the good linearity and stability toward glucose, makes this microbiosensor competent for continuous
in vivo
monitoring of the changes of glucose in rat brains during intraperitoneal injection of insulin. The method demonstrated here can be applied to develop other oxidase-based microbiosensors for other neurochemicals, which would be helpful for understanding the chemical process involved in some physiological and pathological events.
This study demonstrates a new electrochemical microbiosensor for selective
in vivo
monitoring of glucose in rat brains.
Hydrogen sulfide (H
S) plays a pivotal role in gas signal transduction, neuroprotection, and regulation of physiological and pathological processes. However, in vivo tracking the dynamic of hydrogen ...sulfide in the complex brain environment still faces huge challenges. This study demonstrates a new potentiometric method to monitor in vivo the dynamics of hydrogen sulfide in the rat brain using silver nanoparticles (AgNPs)-modified carbon fiber microelectrodes (AgNPs/CFE) pretreated with Na
S (i.e., Ag
S/AgNPs/CFE), which acts as a solid-contact and ion-selective microelectrode. The Ag
S/AgNPs/CFE exhibits good potential response toward hydrogen sulfide in the range of 2.5-160 μM, with a detection limit of 0.8 μM. Because of the presence of Ag
S, the Ag
S/AgNPs/CFE shows good selectivity to hydrogen sulfide, avoiding the interference from coexistent electroactive neurochemicals and the analogies, such as ascorbic acid and cysteine in the central nervous system. This good selectivity combined with the reversibility, protein antifouling, and biocompatibility of the microelectrode enables the Ag
S/AgNPs/CFE to detect hydrogen sulfide in the rat brain during local microinfusion of Na
S and the change in pH. Our study provides a reliable method to track hydrogen sulfide selectively in vivo, which will help to explore the function of hydrogen sulfide in neurophysiology and pathology.
DNA nanohydrogel assembled AuNPs were proposed as a high-throughput multidimensional sensing strategy for small molecule reductant profiling in rat brain. The equilibrium among AuNPs, DNA ...nanohydrogel and targets produced a unique fingerprint-like pattern for differentiating the reducing capacity.
DNA nanohydrogel self-assembled AuNPs were established for small molecule reductant profiling in rat brain.
An absorbance enhanced probe based on gold nanoparticles (GNPs) was proposed for a protein assay in the cerebrospinal fluid of a rat brain. The GNPs, assembled with two aptamers by proximity ...ligation, have high anti-salt properties, and good selectivity and response toward proteins, such as interferon-gamma, in the brain.
The conditional control of protein function in response to the physiological changes of diseased cells is essential to develop smart protein therapeutics. Herein, we report a redox-responsive ...chemical modification of a protein by conjugating an intracellular glutathione (GSH)-cleavable ligand, NSA, onto a protein residue. We demonstrated that the NSA conjugation of Ribonuclease A (RNase A) enabled the control of the protein function by GSH in an aqueous solution and living cells, with extended applications for targeted cancer therapy using a lipid nanoparticle-based intracellular protein delivery strategy.
The chemically modified redox-responsive RNase A-NSA could be selectively activated by up-regulated GSH in live cells for targeted cancer therapy.
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