Unlocking the Power of Magnesium Batteries: Synergistic Effect of InSb-C Composites to Achieve Superior Electrochemical Performance.

Pure magnesium anode used in rechargeable magnesium batteries (RMB) exhibits high theoretical capacity but has been challenged by the passivation issue with conventional electrolytes. Alloy-type anodes have the potential to surpass this issue and have attracted increasing attention. However, the kinetic performance and stabilities of conventional alloy anodes are still constrained. In this study, the InSb-10%C anode is synthesized by a two-step high-energy ball milling process. The InSb-10%C anode exhibits a remarkably high capacity of up to 448 mA h g-1, significantly improved cycle performance (234 mA h g-1 at 100 cycles) and rate performance (168 mA h g-1 at 500 mA g-1). The above-mentioned superior performance of the InSb-10%C anode for RMBs is attributed to the cellular graphitized amorphous carbon composite structure (CGA) which effectively refines the particle size and restricts the volume expansion. Additionally, the reduced surface electron density of InSb combined with the high conductivity resulting from graphitization enhances the Mg2+ diffusion performance. Notably, the InSb-10%C anode demonstrates good compatibility with conventional halogen-free salt ether-based electrolytes in the full battery configuration.

Ratiometric electrogenerated chemiluminescence sensing microRNA based on electrochemically controlled release of lucigenin from silica/chitosan/lucigenin nanoparticles.

The dye-doped silica nanoparticles-based electrogenerated chemiluminescence (ECL) has been widely explored for analytical purposes due to its high sensitivity, simplicity and wide dynamic concentration range. However, only a few of dye molecules located at the near surface of nanoparticles can participate in the ECL reaction due to the poor conductivity of silica nano-matrix. In addition, the ECL signal is easy to be affected by environmental interference, which results in poor accuracy. Herein, a ratiometric ECL sensing method is established based on the electrochemically controlled release of lucigenin molecules from silica/chitosan/lucigenin composite nanoparticles (Lu/CS NPs) with the aid of sulfide ions. Firstly, H+ produced from the electrochemical oxidation of HS- ions can combine with SiO- and displace lucigenin from Lu/CS NPs. The released lucigenin molecules react with the reactive oxygen species (ROS) generated from the electroreduction of dissolved oxygen to produce the cathodic ECL signal. In addition, the excited elemental sulfur from the electrooxidation of HS- ions transfers its energy to lucigenin molecules and makes them be excited to produce energy-transfer anodic ECL signal. Based on these findings, a ratiometric ECL sensor is developed taking the anodic ECL intensity of lucigenin as a reference signal for the cathodic ECL of lucigenin. The proposed ratiometric ECL sensor has been successfully applied to the detection of let-7a with a wide linear range of 0.1-9.0 pM, a low detection limit of 28 fM, high selectivity and good reproducibility. Moreover, the developed approach was used to detect let-7a in human serum composite samples with good recoveries.

TiO2/Ag-based photodeposited catalyst boosted electrochemiluminescence of ninhydrin-hydrogen peroxide system for ultrasensitive sensing of copper (II).

Photodeposited TiO2/Ag nanocomposites were generally used to be a friendly catalyst for degrading organic contaminant in environmental field. However, electrochemiluminescence (ECL) sensing analysis based on photocatalysts remains a significant challenge. Herein, polyvinylimide (PEI)-TiO2/Ag nanocomposites (PEI-TiO2/AgNCPs) film with reduced graphene oxide(r-GO) was constructed as a sensing interface for copper(II) ECL detection. TiO2/Ag nanocomposites was prepared by reversed phase microemulsion method and photodeposition technique. Moreover, it was discovered that a small amount of Cu2+ could obviously boost the ECL signal of ninhydrin-hydrogen peroxide system. Signal amplification was achieved by using the synergistic effect between r-GO and TiO2/Ag nanocomposites, and the efficiently concentrated effect of PEI to Cu2+. Furthermore, the investigation showed that ECL mechanism of ninhydrin-hydrogen peroxide system was attributed to the generated hydroxyl radical and superoxide anion during the several type of reactions. Thus for the first time, an ultrasensitive ECL approach for detecting Cu2+ could be performed using ninhydrin as an ECL signal probe and hydrogen peroxide as a co-reaction reagent. Under the suitable circumstances, the proposed method showed an excellent linear relationship in the concentration range of Cu2+ from 1.0 fM to 5.0 nM. Detection limit was estimated to be as low as 0.26 fM. The sensing interface expanded the application of photodeposited TiO2/Ag nanocomposites in ultrasensitive ECL detection. It has potential applications in other components and biological analysis.

A Carbonate-Involved Amplification Strategy for Cathodic Electrochemiluminescence of Luminol Triggered by the Catalase-like CoO Nanorods.

The lumiol-O2 electrochemiluminescence (ECL) system constantly emits bright light at positive potential. Notably, compared with the anodic ECL signal of the luminol-O2 system, the great virtues of cathodic ECL are that it is simple and causes minor damage to biological samples. Unfortunately, little emphasis has been paid to cathodic ECL, owing to the low reaction efficacy between luminol and reactive oxygen species. The state-of-the-art work mainly focuses on improving the catalytic activity of the oxygen reduction reaction, which remains a significant challenge. In this work, a synergistic signal amplification pathway is established for luminol cathodic ECL. The synergistic effect is based on the decomposition of H2O2 by catalase-like (CAT-like) CoO nanorods (CoO NRs) and regeneration of H2O2 by a carbonate/bicarbonate buffer. Compared with Fe2O3 nanorod (Fe2O3 NR)- and NiO microsphere-modified glassy carbon electrodes (GCEs), the ECL intensity of the luminol-O2 system is nearly 50 times stronger when the potential ranged from 0 to -0.4 V on the CoO NR-modified GCE in a carbonate buffer solution. The CAT-like CoO NRs decompose the electroreduction product H2O2 into OH· and O2·-, which further oxidize HCO3- and CO32- to HCO3· and CO3·-. These radicals very effectively interact with luminol to form the luminol radical. More importantly, H2O2 can be regenerated when HCO3· dimerizes to produce (CO2)2*, which provides a cyclic amplification of the cathodic ECL signal during the dimerization of HCO3·. This work inspires developing a new avenue to improve cathodic ECL and deeply understand the mechanism of a luminol cathodic ECL reaction.

Highly sensitive ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry detection method for levoglucosan based on Na+ enhancing its ionization efficiency.

The sensitive determination of levoglucosan in aqueous samples has great significance for the study of biomass burning. Although some sensitive high-performance liquid chromatography/mass spectrometry (HPLC/MS) detection methods have been developed for levoglucosan, there are still plenty of shortcomings, such as complicated sample pre-treatment procedures, large-amount sample requirements, and poor reproducibility. Herein, a new method for the determination of levoglucosan in the aqueous sample was developed using ultra-performance liquid chromatography with triple quadrupole mass spectrometry (UPLC-MS/MS). In this method, we firstly found that compared with H+, Na+ could effectively enhance the ionization efficiency of levoglucosan, even though the content of H+ is higher in the environment. Moreover, the precursor ion m/z 185.1 [M + Na]+ could be used as a quantitative ion to sensitively detect levoglucosan in aqueous samples. Only 2 µL of un-pretreated sample is required for one injection in this method, and great linearity was obtained (R 2 = 0.9992) using the external standard method when the concentration of levoglucosan was 0.5-50 ng mL-1. The limit of detection (LOD) and quantification (LOQ) were 0.1 ng mL-1 (0.2 pg absolute mass injected) and 0.3 ng mL-1, respectively. Acceptable repeatability, reproducibility, and recovery were achieved. This method has the advantages of high sensitivity, good stability, good reproducibility, and simple operation, which could be widely used for the detection of different concentrations of levoglucosan in various water samples, especially for the detection of samples with low content such as ice core or snow samples.

A highly sensitive fluorescent nanoprobe for the amplified detection of formaldehyde.

Non-conjugated polymer nanoparticles (PNPs) have been widely reported for analytical applications; however, the development of an effective fluorescence signal-amplification scheme based on PNPs remains challenging. In this study, polyethyleneimine-based polymer nanoparticles (PEI-PNPs) were synthesized for interrogating the fluorescence signal-amplification analytical application of the PNPs. The PEI-PNPs with an aggregated PEI polymer structure were able to confine a large density of sub-fluorophores on an individual nanoparticle, enabling the realization of a signal-amplification effect. Herein, formaldehyde (FA) was utilized for enhancing the fluorescence intensity of the PEI-PNPs as a model to confirm our proof-of-concept strategy. Our results showed that a more than 9-fold signaling-enhancing ability for the sensing of FA was observed using the PEI-PNPs prepared with a higher PEI concentration. The possible mechanism for the FA amplified sensing was studied. In particular, the FA-recognition units were sub-fluorophores of PEI-PNPs, which were simultaneously formed with the preparation of the PEI-PNPs avoiding the leakage effect of dyes. We believe that the water-soluble and biocompatible PEI-PNPs are promising candidates for the detection of endogenous FA in living systems.

An Electrocatalysis and Self-Enrichment Strategy for Signal Amplification of Luminol Electrochemiluminescence Systems.

Numerous strategies have been developed to improve the intensity of a luminol electrochemiluminescence (ECL) system due to the low quantum yield of luminol. Notably, considerable research was carried out to improve luminol ECL intensity relying on increasing the concentration of reactive oxygen species (ROS). Herein, a Co-Nx-C electrocatalyst treated with nitric acid or hydrochloric acid (named as Co-POC-O or Co-POC-R, respectively) was in situ prepared on the surface of carbon nanotubes. Surprisingly, compared with Co-POC-R, the Co-POC-O electrocatalyst not only displays excellent oxygen reduction reaction (ORR) performance but also enriches luminol via non-covalent bonds rather than covalent bonds and physical mixing. This method improves the amount of luminol involved in the electrochemical reaction as well as shortens the distance for electron transfer between oxidized luminol and ROS, which significantly enhances the ECL intensity (10-fold higher than that of the bare electrode and 2-fold higher than that of Co-POC-R). The platform realizes highly sensitive dopamine (DA) with a detection limit of 1.0 pM and a linear range from 10 pM to 1.0 nM. In this work, Co-POC-O is both the co-reaction accelerator and carrier material of luminophore species, which provides a new idea to realize ECL signal amplification.

Enhanced electrochemiluminescence of Ru(bpy)3 2+ -doped silica nanoparticles by chitosan/Nafion shell@carbon nanotube core-modified electrode.

Although Ru(bpy)3 2+ -doped silica nanoparticles have been widely explored as the labelling tags for electrochemiluminescence (ECL) sensing different targets, the poor electrical conductive properties of the silica nano-matrix greatly limit their ECL sensitivity. Therefore, a novel scheme to overcome this drawback on Ru(bpy)3 2+ -doped silica nanoparticles ECL is desirable. Here, a new scheme for this purpose was developed based on electrochemically depositing a nanoscale chitosan hydrogel layer on the carbon nanotube (CNT) surface to form chitosan hydrogel shell@CNT core nanocomposites. In this case, the nanoscale chitosan hydrogel layer only formed on the CNT surface due to the superior electrocatalytic effect of CNT on H+ reduction compared with the basic glass carbon electrode. Due to both the superhydrophilic properties and polyelectrolyte features of nanoscale chitosan hydrogel on the CNT surface, chemical affinity as well as the electric conductivity between Ru(bpy)3 2+ -doped silica nanoparticles and CNT were obviously enhanced, and then the ECL effectivity of Ru(bpy)3 2+ inside silica nanoparticles was improved. Furthermore, based on the discriminative interaction of these Ru(bpy)3 2+ -doped silica nanoparticles towards both the ssDNA probes and the ssDNA probe/miRNA complex, as well as the specific adsorption effect of these nanoparticles on the nanoscale chitosan shell@Nafion/CNT core-modified glass carbon electrode, a highly sensitive ECL method for miRNA determination was developed and successfully used to detect miRNA in human serum samples.

A highly sensitive fluorescence sensor based on lucigenin/chitosan/SiO2 composite nanoparticles for microRNA detection using magnetic separation.

In this paper, a convenient reverse-phase microemulsion method for the synthesis of SiO2 nanoparticles (NPs) by simply introducing the chitosan and fluorescent dye of lucigenin during the formation reaction of SiO2 NPs was proposed. Addition of chitosan can make the SiO2 NPs porous, and increases lucigenin molecule incorporation into chitosan/SiO2 NPs nanopores based on electrostatic interaction and supermolecular forces. Therefore, fluorescence quantum yield of the lucigenin/chitosan/SiO2 composite nanoparticles was increased by introduction of chitosan and compared with lucigenin/SiO2 NPs without chitosan. Because the number of negative charges carried when using single-stranded DNA (ssDNA) was different from that of double-stranded DNA (dsDNA), the numbers of lucigenin/chitosan/SiO2 composite nanoparticles with positive charge adsorbed using ssDNA or dsDNA were different. Consequently, fluorescence intensity caused using ssDNA or dsDNA/miRNA was clearly discriminative. With increase in target DNA/miRNA concentration, the difference in fluorescence intensity also increased, resulting in a good linear relationship between fluorescence intensity sensitizing value and target miRNA concentrations. Therefore, a new fluorescence analysis method for direct detection of let-7a in human gastric cancer cell samples without enzyme, label free and no immobilization was established using lucigenin/chitosan/SiO2 composite nanoparticles as a DNA hybrid indicator. The proposed method had high sensitivity and selectivity, low cost and the detection limit was 10 fM (S/N = 3).

The synthesis of PEI core@silica shell nanoparticles and its application for sensitive electrochemical detecting mi-RNA.

Although the silica-based nanoparticles (NPs) have been widely explored as the labels for sensing different targets, the simple and novel scheme, to impose a large number of signal molecules inside silica NPs, is challenge. Herein, a new scheme for this purpose was developed. This new strategy was based on densely doped polyethyleneimine (PEI) inside silica nanoparticles and forming the PEI@silica nanoparticles. Then, the Cu2+ was selected as the electrochemical signal molecule model to be loaded in PEI@silica nanoparticles the based on the strong coordination reaction of Cu2+ with PEI and test its signal amplification ability. Our results showed that 7.6 × 105 Cu2+signal ions could be loaded in a single PEI@silica nanoparticles. Thereafter, based on the discriminating interaction of this PEI/Cu2+/SiO2 NPs towards both ssDNA probes and ssDNA probe/mi-RNA complex, as well as the specific adsorption effect of this NPs on chemically modified electrode, a highly sensitive electrochemical method for detecting mi-RNA was developed and successfully used to detect mi-RNA in the human serum samples.

Electrochemiluminescence observing the surface features of Ru-doped silica nanoparticles based on nanoparticle-ultramicroelectrode collision.

We present an innovative and sensitive electrogenerated chemiluminescence (ECL) strategy for observing the surface feature of a single silica nanoparticle based on its collision with an ultramicroelectrode (UME). As an ECL luminophore, Ru(bpy)3 2+ molecules are doped into silica nanoparticles. The stochastic collision events of Ru(bpy)3 2+ -doped silica nanoparticles (RuSNPs) can be tracked by observing the ECL 'blips' from the ECL reaction of Ru(bpy)3 2+ with a coreactant in solution. When RuSNPs collided with UME, Ru(bpy)3 2+ molecules that only exist near the collision site of silica nanoparticles (NPs) were electrochemically oxidized to form Ru(bpy)3 3+ , and then emitted light, because silica NPs are insulated. The inhomogeneous properties of silica nanoparticle surfaces will produce diverse ECL blips in intensity and shape. In addition, distribution gradients from the he Ru(bpy)3 2+ in a silica matrix also affect ECL blips. Some information on the surface properties of silica NPs can be obtained by observation of single silica collision events.

Enhancing the Electrochemiluminescence of Luminol by Chemically Modifying the Reaction Microenvironment.

As one of the most efficient and commonly used electrochemiluminescence (ECL) reagents, luminol has been paid much attention by the analysts due to its low excitation potential, simple dissolved oxygen-based coreactant ECL reaction requirement, and the widely analytical applications. However, the ECL performances of luminol on most electrode materials suffered from the lower ECL quantum yield, which limited its analytical applications. Herein, it was first found that, compared to that of the bare gold electrode, the ECL quantum yield of luminol on the 1,6-hexanedithiol hydrophobic pinhole film modified gold electrode was 3 times increased. This higher ECL quantum yield of luminol was related to the hydrophobic microenvironment on the surface of the modified electrode, which was formed from the hydrophobic carbon chains on the basis of their supramolecular interaction. On the basis of this new finding as well as the cap effect of gold nanoparticle to these pinhole gates, a highly sensitive ECL sensing scheme for microRNA was also developed.

Study of the controlled assembly of DNA gated PEI/Chitosan/SiO2 fluorescent sensor.

In this paper, polyethylenimine (PEI) and Chitosan were simultaneously one-step doped into silicon dioxide (SiO2 ) nanoparticles to synthesize PEI/Chitosan/SiO2 composite nanoparticles. The polymer PEI contained a large amount of amino groups, which can realize the amino functionalized SiO2 nanoparticles. And, the good pore forming effect of Chitosan was introduced into SiO2 nanoparticles, and the resulting composite nanoparticles also had a porous structure. In pH 7.4 phosphate buffer solution (PBS), the amino groups of PEI had positive charges, and therefore the fluorescein sodium dye molecule can be loaded into the channels of PEI/Chitosan/SiO2 composite nanoparticles by electrostatic adsorption. Furthermore, utilizing the diversity of DNA molecular conformation, we designed a high sensitive controllable assembly of DNA gated fluorescent sensor based on PEI/Chitosan/SiO2 composite nanoparticles as loading materials. The factors affecting the sensing performance of the sensor were investigated, and the sensing mechanism was also further studied.

Label-free electrochemiluminescence assay for aqueous Hg2+ through oligonucleotide mediated assembly of gold nanoparticles.

Development of ultrasensitive method for Hg2+ analysis is important for human health protection and environment monitoring. In this work, we present a highly sensitive and selective electrochemiluminescence (ECL) assay in a "turn-on" mode for the detection of Hg2+ through selective assembly of gold nanoparticles (AuNPs) on the surface of indium tin oxide (ITO) electrode. In the absence of Hg2+, the nonthiolated ssDNA could protected AuNPs against its assembly on ITO surface, producing rather low ECL emission for Ru(bpy)32+/TPA system. Conversely, binding of Hg2+ with the Hg2+-specific oligonucleotide through thymine-Hg2+-thymine coordination formed the double-stranded structure, which could not effectively adsorb to AuNPs in solution. The assembly of free-state AuNPs is achieved, which well preserves electronical conductivity. The presence of AuNPs can catalyze the electro-oxidation of TPA, producing significantly enhanced ECL signal. Through detecting the ECL signal mediated by assembly of AuNPs, the proposed method was able to ensure substantial signal amplification and a low background. It was demonstrated that the ECL intensity was correlated with the ssDNA-based recognition reaction, enabling quantitative analysis of Hg2+ over the range of 8pM to 2nM, with a detection limit of 2pM. ECL intensity of the system were extremely specific for Hg2+ even in the presence of 1000-fold higher concentrations of other metal ions. Analytical results of Hg2+ spiked into water samples by the proposed ECL method were in good agreement with that obtained by atomic fluorescent spectrometry or mass spectrometry data.

Silica Modified Chitosan/Polyethylenimine Nanogel for Improved Stability and Gene Carrier Ability.

Although chitosan-based hydrogel has been widely used as a gene carrier material, further improvement in this aspect is still needed. Herein a new method was proposed for preparing the effective chitosan-based gene carrier nanogel. The new method based on the fact that supra-molecular interactions between silica, polyethylenimine (PEI) and chitosan could be used to self-assemble them together to form a rigid and stable gene carrier material in the reverse microemulsion system. When compared with chemical cross-linking route, the proposed method is simple and easy to adjust components of the resulting nanogel and, therefore, can improve its gene carrying ability. Our results showed that, doping of the PEI and silica into the chitosan hydrogel obviously increased its strength, stability and gene carrying ability.

Amplified electrochemical detection of nucleic acid hybridization via selective preconcentration of unmodified gold nanoparticles.

The common drawback of optical methods for rapid detection of nucleic acid by exploiting the differential affinity of single-/double-stranded nucleic acids for unmodified gold nanoparticles (AuNPs) is its relatively low sensitivity. In this article, on the basis of selective preconcentration of AuNPs unprotected by single-stranded DNA (ssDNA) binding, a novel electrochemical strategy for nucleic acid sequence identification assay has been developed. Through detecting the redox signal mediated by AuNPs on 1, 6-hexanedithiol blocked gold electrode, the proposed method is able to ensure substantial signal amplification and a low background current. This strategy is demonstrated for quantitative analysis of the target microRNA (let-7a) in human breast adenocarcinoma cells, and a detection limit of 16 fM is readily achieved with desirable specificity and sensitivity. These results indicate that the selective preconcentration of AuNPs for electrochemical signal readout can offer a promising platform for the detection of specific nucleic acid sequence.

Sensitive Colorimetric Detection of MicroRNA Based on Target Catalyzed Double-arm Hairpin DNA Assembling.

The common drawbacks of the current colorimetric sensing platform using gold nanoparticles (AuNP) as an indictor is its relatively low sensitivity, which restrict their analytical application for low-level analytes, such as the detection of the microRNA (miRNA). In the present work, we developed a novel strategy to construct a colorimetric sensing platform for miRNA based on target catalyzed hairpin DNA assembling. Unlike a single-stranded DNA probe or a single-arm hairpin structure DNA probe, in our strategy the double-arm hairpin structure DNA probe was first designed, and was further demonstrated to work well in catalysis the of hairpin DNA assembly reaction, which significantly enhanced the sensitivity of the AuNP based colorimetric sensing platform. In addition, compared to other miRNA detection schemes reported previously, the proposed strategy is not only enzyme-free, label-free, immobilization-free, but also eliminates the need for any sophisticated instrumentation. The proposed strategy may open a new way to allow miRNAs expression to be profiled in a decentralized setting, such as at point-of-care.

Highly sensitive detection of copper ions by densely grafting fluorescein inside polyethyleneimine core-silica shell nanoparticles.

In this work, polyethyleneimine (PEI) core-silica shell nanoparticles were synthesized and used for densely grafting fluorescent receptor units inside the core of these particles to result in multi-receptor units collectively sensing a target. Herein, copper ion quenching of the fluorescence intensity of a fluorescein isothiocyanate (FITC) system was selected as a model to confirm our proof-of-concept strategy. Our results showed that, compared to free FITC in solution, a 10-fold enhancement of the Stern-Volmer constant value for Cu(2+) quenching of the fluorescence intensity of the grafted state of FITC in PEI core-silica shell nanoparticles was achieved. Furthermore, compared to a previous collective sensing scheme by densely grafting fluorescent receptor units on a silica nanoparticle surface, the proposed scheme, which grafted fluorescent receptor units inside a polymer nano-core, was simple, highly efficient and presented higher sensitivity.

Amplified fluorescence quenching of lucigenin self-assembled inside silica/chitosan nanoparticles by Cl⁻.

Fluorescence sensing of an analyte based on the fluorophore collective effect is a reliable, sensitive sensing approach. Many ultralow targets can be detected on the basis of the high sensitivity and signal amplification of the fluorescence sensing system. However, the complicated synthesis procedures, harsh conditions required to design and control the fluorescence molecular probes and conjugated chain length, and the higher cost of synthesis are still challenges. To address these issues, we developed a simple, rapid, and sensitive collective effect based fluorescence sensing platform. In this sensing platform, the fluorophore unit was self-assembled on the wall of the nanopores of the porous structural silica/chitosan nanoparticles (SCNPs) on the basis of the electrostatic interaction and supermolecular interaction between the fluorophores and SiO(-) groups and chitosan. Since these self-assembled fluorophores are close enough to communicate with each other on the basis of the space confinement effect of the pore size, many fluorophore units could interact with a single analyte and produce an amplified fluorescence sensing ability. Chloride ion, an important anion in biological fluids, and lucigenin, a typical fluorescent dye, were used as a model to confirm the proof-of-concept strategy. Our results showed that, compared to free-state lucigenin in solution, the assembled-state lucigenin in SCNPs presented an about 10-fold increase in its Stern-Volmer constant when the concentration of Cl(-) was lower than 10 mM, and this fluorescence nanosensor was also successfully used to sense the chloride ion in living cells.

Label-free sensitive electrogenerated chemiluminescence aptasensing based on chitosan/Ru(bpy)3²âº/silica nanoparticles modified electrode.

In this work, a label-free and sensitive electrogenerated chemiluminescence (ECL) aptasensing scheme for K(+) was developed based on G-rich DNA aptamer and chitosan/Ru(bpy)3(2+)/silica (CRuS) nanoparticles (NPs)-modified glass carbon electrode. This ECL aptasensing approach has benefited from the observation that the G-rich DNA aptamer at the unfolded state showed more ECL enhancing signal at CRuS NPs-modified electrode than the binding state with K(+), which folds into G-quadruplex structure. As such, the decreasing ECL signals could be used to detect K(+). Compared to other aptasensing K(+) approaches previously reported, the proposed ECL sensing scheme is a label-free aptasensing strategy, which eliminates the labeling, separation, and immobilization steps, and behaves in a simple, low-cost way. More importantly, because the proposed ECL sensing mechanism utilizes the nanosized ECL active CRuS NPs to sense the nanoscale conformation change from the aptamer binding to target, it is specific. In addition, due to the great conformation changes of the aptamer's G-bases on CRuS NPs and the excellent ECL enhancing effect of guanine bases to the Ru(bpy)3(2+) ECL reaction, a 0.3 nM detection limit for K(+) was achieved with the proposed ECL method. On the basis of these advantages, the proposed ECL aptasensing method was also successfully used to detect K(+) in colorectal cancer cells.