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Organic photoelectric materials with conjugated electron-rich structures and good biocompatibilities have broad application prospects in biosensors. Herein, we report a promising organic photoelectric multielectron donor nanocomposite for highly sensitive PEC immunoassays. Specifically, the organic multielectron donor nanocomposite (DA-ZnTCPP

Designing and screening highly efficient and cost-effective luminophores have always been a challenge to develop sensitive electrochemiluminescence (ECL) biosensors. Herein, polyethyleneimine nanoparticles (PEI NPs), a kind of nonconjugated polymer (NCP) NPs with tertiary amine clusters, were developed as an ECL luminophore. Specifically, PEI NPs were synthesized by a one-step hydrothermal method using PEI and formaldehyde. The properties of PEI NPs were investigated in detail using photochemical and electrochemical techniques. The results showed cluster-dominated luminescence of tertiary amines in PEI NPs via "through-space conjugation". This non-negligible ECL performance (at 631 nm) was also verified by the initiated reduction-oxidation process. With persulfate as a coreactant, PEI NPs acted as both the luminophore and coreaction accelerator to enhance the ECL intensity remarkably, which was eightfold higher than that of isolated PEI. Moreover, choosing dopamine as the model target, a highly sensitive "signal off" ternary ECL sensor was constructed utilizing PEI NPs as the luminophore. Dopamine could be oxidized to benzoquinone at the sensing interface, quenching the signal via ECL energy transfer. Free from any signal amplification, the proposed sensor achieved a low detection limit (4.3 nM) for target monitoring with good selectivity and stability. This strategy not only provides a unique perspective for designing novel efficient and facile ECL luminophores of tertiary amines but also broadens the biological application of NCP NPs.

Despite the upsurging interest in electrochemiluminescence (ECL) of lanthanides, the research in this field is still in its infancy due to the low intensity. In this work, a series of Ce3+-doped terbium orthophosphates (TbPO4:Ce) in different proportions have been synthesized through the co-precipitation method at room temperature. Meanwhile, through the investigation of morphologies and ECL properties of these TbPO4:Ce, it is concluded that the ECL intensity reaches the maximum when the molar ratio of Tb/Ce is 9:1 and the material is nanorod-shaped. The ECL intensity of TbPO4:Ce is significantly improved by doping with Ce3+ due to the dual sensitization strategy of the antenna effect from PO43- to Tb3+ and the energy transfer from Ce3+ to Tb3+. Interestingly, doping with Ce3+ can not only adjust morphology of TbPO4:Ce but also improve the ECL intensity. In addition, to verify the application of TbPO4:Ce, two single mucin1 (MUC1) aptamers are linked together to form a dual MUC1 aptamer chain. Then, a simple and sensitive ECL biosensor is constructed for the detection of MUC1, which can recognize the double amount of MUC1 and quench the ECL signal. As expected, the proposed biosensor shows good stability and acceptable selectivity and achieves sensitive detection of MUC1 with a dynamic range from 1 fg·mL-1 to 10 ng·mL-1 and a limit of detection of 0.5 fg·mL-1. This work may pave a new avenue for the study of direct ECL emission of lanthanides and prove to be ideal for the research of new ECL luminophores in electrochemical analysis.

Designing photovoltaic materials with good photoelectric activity is the crucial to boost the sensitivity of photoelectrochemical (PEC) biosensors. To meet this concern, a Schottky-functionalized direct Z-scheme heterojunction photovoltaic material was proposed by electrodeposition of gold nanoparticles on two kinds of bismuth oxyhalide composites surface (bismuth oxybromide and bismuth oxyiodide with different but matched band gaps) (depAu/BiOI/BiOBr). Specifically, synergistic effect was achieved through the direct Z-scheme heterojunction formed by BiOBr and BiOI as well as the gold Schottky junction, resulting in the enhanced light harvest and photoelectric conversion efficiency. Meanwhile, combined with sandwich immunotechnology, a "signal-off" PEC biosensor was fabricated for highly sensitive detection of carcinoembryonic antigen (CEA). In which, using depAu/BiOI/BiOBr modified glassy carbon electrodes both as the photoactive sensing interface and capture antibody loading matrix, polyethyleneimine copper complex encapsulated gold nanoclusters labeled detection antibody (Ab

To meet the growing concerns about food safety, sensors for tetracycline antibiotics have been urgently needed. Herein, we synthesized a series of binuclear coordination polymers (Tb-Zn-CPs) based on lanthanide and transition metal ions by solvothermal method using [1,1':4',1''-terphenyl]-3,3'',5,5''-tetracarboxylic acid, Tb(NO

A photoelectrochemical (PEC) biosensor is a very efficient and sensitive detection technology for the quick and effective conversion of light to electrical signals. However, the sensitivity and stability of the sensors are still unsatisfactory based on single-phase semiconductors or in the absence of sacrificial agents in the test solution. Herein, we present an efficient curing sacrificial agent-induced dual-heterojunction PEC system, which can detect the prostate-specific antigen (PSA) with high sensitivity. This PEC immune system was initially fabricated using single-walled carbon nanohorns (SWCNHs), p-type MoS2, and n-type Ag2S successively through a Schottky junction and p-n heterojunction on a glassy carbon electrode with electrodeposited gold nanoparticles. Then, the capture antibody (Ab1) was modified and the nonspecific binding sites were sealed off. Meanwhile, the ferrocene (Fc) solidified with hollow nanospheres of zinc ferrite (ZnFe2O4) served as a curing electronic sacrificial agent (Fc-ZnFe2O4). Next, the detection antibody labeled with Fc-ZnFe2O4 (Ab2-Fc-ZnFe2O4) was used as a bio-nanoprobe and captured by PSA and Ab1 via sandwich immunorecognition. Under white light, PEC signal amplification could be driven by the curing electronic sacrificial agent-induced dual-heterojunction to achieve the highly sensitive detection of the target. This proposed system exhibited excellent photocurrent performance within the working range from 1 fg·mL-1 to 100 ng·mL-1 at a low detection limit of 0.44 fg·mL-1 (S/N = 3). The proposed strategy features high sensitivity, selectivity, and stability that provides a new opportunity for the development of biosensors in the PEC field.

Metal organic gels (MOGs) as a new type of porous soft-hybrid supramolecular material have attracted widespread interest in various aspects due to their unique optical properties. In this work, we report a novel electrochemiluminescence (ECL) emission (679 nm) lanthanide MOG, which has been synthesized by a simple and rapid method at room temperature. This MOG (Tb-Ru-MOG) consists of a central metal ion, terbium (III), and two different ligands, tris(4,4'-dicarboxylicacid-2,2'-bipyridyl) ruthenium (II) dichloride (Ru(dcbpy)32+) and 4'-(4-carboxyphenyl)-2,2':6',2″-terpyridine (Hcptpy). Compared with the classic system of tris(2,2'-bipyridyl) ruthenium (II) dichloride (Ru(bpy)32+)/S2O82-, Tb-Ru-MOG/S2O82- owns a narrower potential sweep range (0.00 to -0.85 V) and a more stable and stronger ECL signal. Interestingly, the ECL intensity only decreased 2.0 and 0.1% after continuous scanning for 8000 s and storing at room temperature for 3 months. The possible ECL mechanism has been discussed in detail, which is mainly attributed to the internal synergies (antenna effect and energy transfer) and external co-reactant. Inspired by the unique luminescence characteristics of Tb-Ru-MOG, the application in electroanalytical chemistry was identified by the ECL on-off response for epinephrine with a linear range from 1.0 × 10-10 to 1.0 × 10-3 mol·L-1 and a detection limit of 5.2 × 10-11 mol·L-1. The results suggest that the as-proposed Tb-Ru-MOG will provide a robust pathway for new ECL luminophores in analysis.

The pursuit for improving photoelectrochemical (PEC) performances of organic materials remains an urgent need. Here, we have proposed an envision of the preparation the metal-organic frameworks (MOFs) with arenes to realize high photo-to-current conversion efficiency and excellent PEC performances. Magnesium 3,4,9,10-perylene tetracarboxylic acid metal-organic frameworks (Mg-PTCA MOFs) were synthesized for the first time. The uniformly distributed and regular-shaped Mg-PTCA MOFs showed a much more stable and higher photocurrent than the single PTCA and its derivatives, which confirmed our hypothesis. A regenerated-biosensor was designed for microRNA analysis based on Mg-PTCA MOFs as a novel photoelectric material, target-triggered three-dimensional DNA Scaffold (3D-Sca) as an efficient signal amplifier, and gold nanoclusters (Au NCs) as quencher. The elaborately designed biosensor achieved ultrasensitive detection for miRNA 21 with a dynamic range from 10 aM to 10 pM and a detection limit of 2.8 aM. This biosensor showed good analytical performance in the extracts of different cancer cells, indicating the possibility for early diagnosis, timely staging assessment, and accurate prognostic judgment for diseases. The recommendable performances of Mg-PTCA MOFs highlight the significance of organic MOFs in PEC sensing.

Self-enhanced electron donor-acceptor type coumarin 545 aggregates prepared via an anionic surfactant-assisted reprecipitation method provide an underlying approach for the photoelectrochemical detection of L-cysteine, which can be employed in aqueous solution without the addition of electron donors.

A novel signal self-enhancement photoelectrochemical immuno-sensor has been developed based on the curing of sacrificial agent SO32- coated-Au NPs sensitizing Ag2S/CuS/α-Fe2O3 n-p-n hetero-structure films for the first time. This strategy has acquired high sensitivity and low background without addition of a sacrificial agent in solution in the detection of prostate antigen.

Novel lanthanum ion-doped cadmium sulfide quantum dots (CdS:La QDs) were synthesized and characterized by transmission electron microscopy (TEM) and photoluminescence (PL). Based on CdS:La QDs as the electrochemiluminescence (ECL) luminophores, a distance-dependent ECL intensity enhanced or quenched system between CdS:La QDs and gold nanoparticles (Au NPs) was designed. Firstly, ssDNA 1 was linked to the CdS:La QDs modified glassy carbon electrode via amide bond. Then the prepared Au NP–ssDNA 2 conjugates were used to hybridize with ssDNA 1, the surface plasmon resonances (SPR) of Au NPs enhanced ECL intensity (signal on) while Au NPs and CdS:La QDs were separated at a certain distance. Secondly, In the presence of Hg2+, the oligonucleotide conformation changed from linear chain to hairpin due to the thymine–Hg2+–thymine (T–Hg2+–T) base pairs. ECL quenching (signal off) achieved lie in resonance energy transfer (RET) between the CdS:La QDs and the proximal Au NPs at a close distance. Finally, after being incubated with TB, a strong and stable TB–aptamer complex was generated, which led to the release of Au NP–ssDNA 2 conjugates. The ECL signal of the CdS:La QDs was ultimately recovered (signal on again). The “on–off–on” approach was used to detect Hg2+ and TB, sensitively and respectively. The line ranges were 1.00 × 10−12 –1.00 × 10−5 mol L−1 and 1.00 × 10−16 –1.00 × 10−6 mol L−1, respectively. The low limits of detection (S/N = 3) were at 3.00 × 10−13 mol L−1 and 3.00 × 10−17 mol L−1. Moreover, the ECL sensor exhibited high selectivity and good stability, and was successfully applied to the detection of TB in real sample.

A self-enhanced photoelectrochemical copper ions sensor was constructed using an organic electron donor matrix with a Schottky heterostructure prepared from dopamine and single walled carbon nanohorns. The determination of Cu

Self-enhanced electron donor-acceptor type coumarin 545 aggregates prepared

A high initial signal for the sensitive detection of analytes is critical in photoelectrochemical (PEC) biosensing systems. As a semiconductor, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) possesses an appropriate optical band gap of 2.5 eV and inherently intense and stable PEC response. When gold nanoparticles (Au NPs) are electrodeposited on the surface of PTCDA to form a Schottky junction (Au NPs/PTCDA), a surprising and satisfactory PEC performance is unfolded before our eyes. Considering the outstanding PEC behaviors of Au NPs/PTCDA and the great quenching effect of gold nanoclusters (Au NCs), the "ON-OFF-ON" PEC sensing platform has been developed for microRNA 1246 (miRNA 1246) detection combined with the cascaded quadratic amplification strategy of the polymerization/nicking reaction and dual-particle 3D DNA roller. The higher initial PEC signals of the system can be acquired by regulating the deposition time for 35 s (-0.2 V), which is derived from the synergetic effect of localized surface plasmon resonance of Au NPs and the formation of a Schottky junction. The dual-particle 3D DNA roller has been designed to guarantee wide walking space, remarkable operation performances, and inhibition of derailment. The proposed biosensor shows a dynamic range from 10 aM to 1 pM at a low detection limit of 3.1 aM and exhibits good analytical behaviors while analyzing miRNA 1246 in healthy human serum samples. This work not only expands the application of organic photoelectric materials in bioanalysis but also provides potential possibility of detecting other biomarkers by choosing appropriate target units.

Early monitoring of prostate-specific antigen (PSA) is crucial in diagnosis and proactive treatment of prostate disease. Herein, a dual-quenching ternary ECL immunosensor was designed for PSA detection based on graphitic carbon nitride quantum dots (g-CNQDs, as an emitter), potassium persulfate (K2S2O8, as a coreactant), and silver nanoparticles doped multilayer Ti3C2 MXene hybrids (Ag@TCM, as a coreaction accelerator). First, Ag@TCM was immobilized on the surface of a glassy carbon electrode, then g-CNQDs was further adsorbed on Ag@TCM to acquire a higher initial ECL signal at a potential window from − 1.3 to 0.0 V (vs. Ag/AgCl). Ag@TCM not only acted as the coreaction accelerator, but also as a matrix to load enormous g-CNQDs and prostate-specific capture antibody via Ag–N bond. Meanwhile, prostate-specific detection antibody was marked by gold nanoparticles modified manganese dioxide as a dual-quenching probe (Ab2- Au@MnO2). When Ab2-Au@MnO2 was introduced into the ternary ECL system via sandwiched immuno-reaction, the high-sensitive detection of PSA was achieved by the dual-quenching effect, caused by the resonant energy transfer from g-CNQDs (energy donor) to Au@MnO2 (energy acceptor). As a result, this ECL immunosensor showed a good dynamic concentration range from 10 fg·mL−1 to 100 ng·mL−1 with a detection limit of 6.9 fg·mL−1 for PSA detection. The dual-quenching ECL strategy presented high stability and good specificity to open up a new pathway for ultrasensitive immunoassay.

MicroRNAs (miRNAs) assay is of great significance for early diagnosis of diseases, so an enzyme-free “on-off-on” PEC biosensor has been developed for sensitive miRNA 141 determination. Manganese-doped cadmium sulfide coupled with zinc sulfide quantum dots (Mn:CdS@ZnS QDs) and manganese porphyrin (MnPP) have been used as photoelectric material and photosensitizer, respectively. And a high photocurrent of approximately 70.0 μA has been obtained. Cascaded quadratic amplification strategy has been applied in the system. Mn:CdS@ZnS QDs was characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), X-ray photoelectron spectrum (XPS) and energy dispersive X-ray spectroscopy (EDX). Photoelectrochemical and electrochemical technologies were used to monitor the fabrication process of the biosensor. The sensing platform exhibits recommendable stability and good selectivity, miRNA 141 can be accurately quantified with a linear range of 1.00 × 10−14 to 1.00 × 10-8 mol·L-1 and the detection limit of 3.30 fmol·L-1. This method provides promising potential to explore sensitive detection models for various biological molecules.

The excellent characteristics of porphyrins have inspired widespread interest in electrochemiluminescence (ECL). However, the limited ECL intensity and poor stability of porphyrins in aqueous solution are still severely restricted further biological application. Here, we subtly synthesized a functionalized europium and 5,10,15,20-tetrakis (4-carboxyphenyl) porphyrin (TCPP) coordination polymer (Eu-PCP) by a one-step solvothermal method. In sharp contrast to the pristine TCPP, Eu-PCP showed a higher and more stable ECL red-light emission (673 nm) at low potential (−1.1 V, vs Ag/AgCl), which was 7.7-fold higher ECL intensity and 4.6-fold efficiency. In view of the crucial role of mucin 1 (MUC1) in tumor overexpression, it was selected as the target molecule. Combined with exonuclease III (Exo III)-assisted recycling amplification strategy, a ternary ECL biosensor was constructed for the MUC1 detection based on Eu-PCP as a satisfied ECL emitter, gold nanoparticles capped CeO2 (CeO2@Au) as the coreactant accelerator and peroxydisulfate as coreactant. Meanwhile, gold nanoparticles capped MnO2 (MnO2@Au) was used as the quenching probe to achieve a highly sensitive detection of MUC1. The proposed biosensor exhibited a wide linear range from 1 fg mL−1 to 10 ng mL−1 with a low limit of detection (0.32 fg mL−1). By changing the corresponding target recognition DNA, this strategy could be expanded to detect other biomarkers.

A novel internal standard electrochemiluminescence (ECL) sensor has been designed for the detection of ascorbic acid (AA). The adopted dual-emission luminophore (NSGQDs-PEI-luminol-Pt) is composed of nitrogen and sulfur double-doped graphene quantum dots (NSGQDs, as the main luminophore), luminol (as the auxiliary luminophore and internal standard), platinum nanoparticles (Pt NPs, as the co-reaction accelerator), and polyetherimide (PEI, as the linker of NSGQDs and luminol). The results suggest obviously enhanced ECL intensities by the Forster resonance energy transfer (FRET) between luminol (donor) and NSGQDs (acceptor). In this sensing system, the cathodic ECL intensities of NSGQDs (ECL-1, −1.8 V vs. Ag/AgCl) gradually decrease with increasing concentration of AA, while the anodic ECL intensities of luminol (ECL-2, 0.3 V vs. Ag/AgCl) almost remain essentially constant at a potential window from −2.0 to 0.4 V. The natural logarithm of the ratio between ECL-1 and ECL-2 (ln I (ECL-1/ECL-2)) shows a good linear relationship with AA concentration ranging from 10 to 360 nM. The regression equation is ln I (ECL-1/ECL-2) = − 0.0059 cAA + 3.55 (R2 = 0.992) with a limit of detection of 3.3 nM. Such sensor has also been applied for monitoring AA in human serum. The recovery range was 96.5–105.3% and the relative standard deviation was 1.3–3.3%.

Over the recent years, the role of trimethylamine N-oxide (TMAO) as a gut-derived metabolite mediating cardiovascular disease pathogenesis has been under particularly intense scrutiny. The aim was to explore whether TMAO levels were associated with clinical severity or functional outcome in Chinese patients with ischemic stroke.This is a single-center, prospective cohort study from Xiamen, China. We examined the relationship between fasting TMAO and 2 of its nutrient precursors, choline and betaine, vs. 3-month functional outcome and mortality in 351 first-ever patients with acute ischemic stroke.The median value of the plasma level of TMAO was 6.1 μM (IQR, 3.7-9.9 μM), which was higher than in those control cases (4.0; 2.4-5.9 μM). Patients with a poor outcome and nonsurvivors had significantly increased TMAO levels on admission (P 0.001). Following adjustments for traditional risk factors, increased TMAO concentrations remained predictive of both poor outcome and mortality risks in stroke patients [e.g., quartiles 4 vs 1, odd ratio 5.65 (95% CI, 2.87-13.45), P 0.001; and 5.84 (95% CI, 3.05-16.12), P 0.001, respectively]. In multivariate analysis, TMAO was an independent predictor of functional outcome and mortality and improved the prognostic accuracy of the NIHSS to predict functional outcome (combined areas under the curve, 0.82; 95% CI 0.77-0.89, P = 0.003) and mortality (combined areas under the curve, 0.85; 95% CI: 0.80-0.90, P = 0.002).Fasting plasma concentrations of gut microbial TMAO are higher in patients with ischemic stroke and portend higher poor functional outcome events and mortality.

The design and exploration of highly efficient organic luminophores for an electrochemiluminescence (ECL) sensor is a fascinating and promising subject. Herein, we present a surfactant-assisted self-assembly of 5,10,15,20-tetrakis (4-carboxyphenyl) porphyrin (TCPP) J-aggregate as a robust organic luminophore to construct the solid-state ECL sensing platform with significantly enhanced and constantly stable signals, by using peroxydisulfate (S

Peroxydisulfate-oxygen (S2O82−-O2) system has become one of the most used systems in electrogenerated chemiluminscence (ECL) field. Due to S2O82− can be used as Fenton Reagent, this work designed an ECL biosensor based on the S2O82−-O2 system for the detection of L-alanine in a widened emission window and using hemin/G-quadruplex and platinum and palladium nanowires (Pt-Pd NWs) to in situ generate O2 to amplify the ECL intensity. The proposed ECL sensor showed an excellent analytical property for the detection of L-alanine in a linear range of 5.0 × 10−3 M to 1.0 × 10−8 M with the detection limit of 3.3 × 10−9 M (S/N = 3). This work with high selectivity, stability and reproducibility may open a new door to apply S2O82− in ECL field.

A simple enzyme-based nanohybrid material was fabricated via immobilizing ascorbic acid oxidase (AO) on the surface of flower-like electrodeposited gold nanoparticles (dpAu) and reduced graphene oxide (rGO) modified glassy carbon electrodes (GCEs). The composite material was used for stereoselective interaction with ascorbic acid (AA) and isoascorbic acid (IAA). Herein, AO was applied as a stereoselective selector, and the dpAu/rGO nanohybrid not only acted as a supporter for high loading of AO, but also served as the nanomaterial for signal amplification. The results showed obvious peak current differences between AA and IAA, indicating that this strategy could be employed to recognize AA and IAA. Under the optimum conditions, the sensor exhibited a good linear response to AA and IAA in a linear range of 1.0 × 10-4 - 5.0 × 10-3 M. This approach with the merits of simplicity and rapid response provided a promising perspective for identification of AA and IAA.

Herein, a simple and convenient chiral sensor for tyrosine (Tyr) enantiomer recognition was developed based on a simply synthesized nanomatrix, which was coupled to L-cysteine-functionalized fullerene (C60-L-Cys), porous Au@Pd bimetallic nanoparticles (Au@Pd), and thiol-β-cyclodextrin (HS-β-CD). The nanomatrix was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). Electrochemical interactions between Tyr enantiomers and the nanomatrix-modified glassy carbon electrodes (GCEs) were investigated via square wave voltammetry (SWV). The results showed obvious differences between the peak currents of Tyr enantiomers, hinting that Tyr enantiomers could be effectively recognized by the sensor. This method provides a promising perspective to identify Tyr enantiomers with the advantages of simple preparation, rapid response, excellent stability, and reproducibility.

In this paper, a simple stereoselective sensing platform for the recognition of ascorbic acid (AA) and isoascorbic acid (IAA) was fabricated via immobilizing HS-β-cyclodextrin (HS-β-CD) on the surface of nanocomposite modified glassy carbon electrodes (GCEs). The nanocomposites were prepared using Pt and Pd bimetal nanowires (Pt–PdNWs) and reduced graphene oxide (rGO). The preparation process was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). After the modified electrodes interacted with the analytes, obvious differences in the peak currents of AA and IAA were obtained, hinting at the ability of the proposed sensor to recognize AA and IAA. This sensor with simple preparation, a rapid response, and excellent stability and reproducibility provided a promising perspective to recognize and determine AA and IAA.

The present study adopts a new political intervention analysis approach to evaluate the impact of the “21st Century Maritime Silk Road” (MSR) policy. The basic concept is to investigate dependence amongst cross-sectional units to construct counterfactuals without intervention. Thus, the effect of policy intervention is simply the difference between the outcomes with and without intervention. The panel data of 14 countries along MSR are used to illustrate the methodology. Real data analysis shows that the MSR policy exerts a positive effect on the trade of China and Southeast Asian countries. Furthermore, policy implications are provided based on the analysis. Key words: Political intervention analysis, Panel data, Time series, Factor analysis model. JEL: C13, C33, E65, F17. Merenje koristi strategije razvoja “pomorskog puta svile 21. veka” putem pristupa analize intervencija: Dokazi iz Kine i susednih zemalja u jugoistocnoj Aziji Istraživanje koristi novi pristup analize politickih intervencija kako bi procenio uticaj politike “pomorskog puta svile 21. veka” (MSR). Osnovna koncepcija je da se prouci zavisnosti među presecnim jedinicama radi konstruisanja stanja bez intervencije. Stoga je efekat politike intervencije jednostavno razlika između rezultata sa i bez intervencije. Podaci panela sa 14 zemalja uz MSR su koriscena za ilustraciju metodologije. Analiza realnih podataka pokazuje da politika MSR pozitivno utice na trgovinu Kine i jugoistocne Azije. Pored toga, na osnovu analize date su implikacije rezultata na politiku. Kljucne reci: Analiza politickih intervencija, podaci panela, vremenske serije, model faktorske analize.

Herein, an ultrasensitive and stereo-selective electrochemiluminescent (ECL) biosensor based on ECL signal amplification of luminol by the synergetic catalysis of a hemin-functionalized composite and gold–platinum nanowires (Au-PtNWs) has been designed for the detection of D-alanine (D-Ala). In the sensor design, D-amino acid oxidase (DAAO) was used to generate the ECL co-reactant (H2O2) for luminol in situ. The reduced graphene oxide-hemin-cysteine (rGO-H-Cys) composite and Au-PtNWs acted not only as amplification labels to amplify signals via synergetic catalysis, but also as an ideal nanocarrier to accelerate electron transfer. A great difference in ECL intensities toward D-Ala and L-Ala was obtained, and an obviously higher intensity was seen for D-Ala. Under optimal conditions, the ECL intensity had a linear relationship with the logarithm of the D-Ala concentration in the range from 1.0 × 10−9 to 5.0 × 10−3 M with a detection limit of 3.3 × 10−10 M (S/N = 3). This study provides a new method for the determination of D-Ala in food with high sensitivity, excellent selectivity, and good stability and reproducibility.

The enthusiasm of many chemists for green chemistry has increased due to its clean and sustainable features. Here, plant leaf-derived carbon dots (CDPs) and oxidized CDPs (o-CDPs) were synthesized through a simple pyrolytic procedure. The results of the controlled trial showed that the electrochemiluminescence (ECL) performances of o-CDPs were significantly better than those of CDPs. Among them, oxidized maple CDP (o-CDP-M) exhibited the highest ECL intensity with a maximum emission wavelength of 520 nm and could be used as a new type of "green source" luminophore. In view of the considerable role of microRNA-21 (miRNA-21) in tumour overexpression, it was chosen as the target molecule. In combination with the cascade amplification strategy, an ultrasensitive “signal-on” ECL biosensor based on o-CDP-M was developed. Possessing the merits of eco-friendliness and high selectivity, the proposed biosensor achieved ultrasensitive detection of miRNA-21 with a dynamic range from 1 fM to 1 nM and a detection limit as low as 0.27 fM. It was successfully used to analyse miRNA-21 in tumour cell extracts. This work provides a new opportunity for synthesizing “green source” luminophores and detecting various trace miRNA species.

Exploring novel near-infrared (NIR) luminophore with highly efficient and benign is strongly anticipated for electrochemiluminescence (ECL) evolution. Here, three kinds of porphyrin dots including 5,10,15,20-tetrakis (4-carboxyphenyl) porphyrin (TCPP) dots, ZnTCPP dots and TCPP-based metal organic framework (pMOF) dots have been subtly synthesized for the first time by a universal straightforward exfoliation of bulk porphyrin aggregates or pMOF. These as-designed porphyrin dots perform excellent annihilation ECL activity, also exhibit stable and robust cathodic or anodic NIR ECL properties with different coreactants (potassium peroxydisulfate, hydrogen peroxide or tri-n-propylamine) in aqueous phase. Especially, the ECL efficiency of three kinds of porphyrin dots in S2O82− cathodic system are 56, 44, 39-fold higher than that of the Ru(bpy)32+ standard, respectively. As a new type of ECL luminophores, TCPP dots coupled with a lead ion-dependent DNAzyme and hybridization chain reaction cycle amplification are used to fabricate a label free “signal-on” ECL biosensor for ultrasensitive detection of Pb2+. A dynamic range from 10 pmol·L−1 to 1 μmol·L−1 with a low limit of detection (1.2 pmol·L−1) is obtained. These porphyrin dots provide evidence for the use of organics-based dots as new NIR ECL luminophores for fundamental ECL research, and highlight the significance of small-sized organic nanomaterials in ECL sensing applications.

The construction of an electrochemiluminescence (ECL) biosensor achieving sensitive detection of cancer markers by improving the intensity of luminescent materials and the effect of quenchers is still under study. Herein, we designed an ECL sandwich immunosensor for sensitive detection of prostate specific antigen (PSA), which integrated gold nanoparticles functionalized Mo-polydopamine hollow sphere (Au@Mo-PDA, as a quencher) with platinum nanoparticles modified conjugated microporous polymer (Pt-CMP, as a luminophore) in the presence of triethanolamine (TEOA, as a coreactant). First, CMP with large specific surface area and high porosity was electropolymerized on glassy carbon electrodes (GCEs) employing carbazole-riched 2,6-di(9H-carbazol-9-yl) anthracene-9,10-dione as a precursor. Then, platinum nanoparticles were electrodeposited on CMP to construct a high initial ECL intensity system (signal on). Meanwhile, Pt-CMP with good biocompatibility could be used as a matrix to load a mass of prostate specific capture antibody (Ab1). When the Au@Mo-PDA labelled prostate specific detection antibody (Ab2) was introduced via sandwich immuno-reaction, the quantitative detection of PSA was realized by the quenching effect of Au@Mo-PDA since the quinone unit in Mo-PDA could annihilate the excited state of Pt-CMP* (signal-off). The proposed ECL system performs a good linearity to PSA concentration ranging from 10 fg mL−1 to 5 ng mL−1 with a low detection limit of 4.2 fg mL−1 and possesses high selectivity, stability and reproducibility. This work provides a versatile platform for the application of Mo-polydopamine based hollow sphere and conjugated microporous polymer in ECL biosensors.

This paper describes an electrochemiluminescent (ECL) based method for chiral recognition and detection of both glutamate (Glu) enantiomers. The luminophore luminol (Lum) was used as both the reductant and stabilizer of Ag nanoparticles (AgNP-Lum) which were combined with carbon quantum dots (C-dots) and placed on a glassy carbon electrode (GCE) along with the enzyme glutamate oxidase (GluOx). The use of these materials is found to result in strong amplification of ECL. The nanomaterials used were characterized by transmission electron microscopy (TEM) and Fourier transform infrared (FTIR). The stepwise fabrication of the electrode was verified by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under optimized conditions and by applying a typical potential of 0.6 V, the ECL increases linearly in the 5.0 μM to 5.0 mM Glu concentration range, with a 1.6 μM lower detection limit and satisfactory selectivity. A Glu logic gate idea has been designed that is based on this enzymatic biosensor.

A novel solid-state electrochemiluminesence (ECL) "on-off" switch system for highly sensitive detection of tryptophan based on the luminescence-functionalized ruthenium metal-organic framework (Ru-MOF) nanoflowers and CdS quantum dots (CdSQDs) was described. Ru-MOF nanoflowers were prepared by a one-step solvothermal method at low temperature and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR) spectra and fluorescence (FL) spectra. For potential applications, the Ru-MOF nanoflowers were used to fabricate an ECL "on-off" switch sensor with CdSQDs for the detection of tryptophan enantiomers by quenching effect. Meanwhile the functionalized fullerene nanoparticles were used to enhance signal intensity. Furthermore, the stepwise modified process was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The proposed ECL sensor had a wide linear range from 1.0 nM to 1.0mM with a lower detection limit of 0.33nM for tryptophan enantiomers. This method was simple to prepare, fast to operate, with good sensitivity and excellent stability for the development of efficient and practical ECL sensors.

A new stable and stereo-selective electrochemiluminescence (ECL) interface has been designed for specific recognition of penicillamine (Pen) enantiomers by using hemoglobin (Hb) and gold nanoparticles functionalized graphite-like carbon nitride nanosheets composite (Au-g-C3N4 NHs) modified glassy carbon electrodes (Hb/Au-g-C3N4/GCE). The advantages of Hb as chiral selector and Au-g-C3N4 NHs as luminophore were perfectly displayed in this novel interface. The obviously different ECL intensity was exhibited after l-Pen and d-Pen adsorbed on Hb/Au-g-C3N4/GCE, and a larger response was observed on d-Pen/Hb/Au-g-C3N4/GCE. Under the optimum conditions, the developed ECL chiral sensor showed excellent analytical property for detection of Pen enantiomers in a linear range of 1.0×10-4M to 5.0×10-3M, and the detection limits of l-Pen and d-Pen were 3.1×10-5M and 3.3×10-5M (S/N=3) respectively. This work with high selectivity, stability and reproducibility may open a new door based on ECL to discriminate Pen enantiomers.

An electrochemiluminescence (ECL) three-dimensional (3D) DNA nanomachine is developed for microRNA-141 (miRNA-141) detection by coupling Pb2+ dependent DNAzyme assisted target recycling amplification technology with multiple ECL resonance energy transfer (ECL-RET) system. Firstly, Pb2+ dependent DNAzyme is formed by three single strand DNA (ssDNA): A1, A2 and the target miRNA-141. In the presence of Pb2+, the specific recognition site of the DNAzyme is cleaved and a large number of secondary targets (A3) are released. Secondly, the 3D DNA nanomachine consists of four ssDNA: H1, H2, H3 and the probe (two ends are labeled with alexa fluor (AF) and a nanocomposite (PtNCs@Ru(dcbpy)32+) which is prepared by polyethyleneimine platinum nanoclusters and tris(4,4′-dicarboxylicacid-2,2′-bipyridyl) ruthenium(II) dichloride). Then, the 3D DNA nanomachine is assembled on the gold nanoparticles modified glassy carbon electrode. Afterwards, A3 is employed to hybridize with the probe, triggering the movement of the nanomachine and forming the multiple ECL-RET system. In this system, AF, serves as an effective energy transfer donor, which can transfer energy to PtNCs and Ru(dcbpy)32+directly. Meanwhile, PtNCs, both as the acceptor and donor, can accept energy from AF and transfer it to Ru(dcbpy)32+. As a result, The biosensor achieves enhanced ECL efficiency, which is 1.78 times that of the classic tris(2,2′-bipyridyl)ruthenium(II) dichloride (Ru(bpy)32+) and exhibits good responses to miRNA-141 in the linear range from 10 aM to 100 nM with a detection limit of 3.3 aM. Also, the obtained biosensor can be employed to detect miRNA-141 in human serum samples, which will be of great significance in bioanalysis.

Nitrogen-doped graphene quantum dots (N-GQDs) were prepared from dicyandiamide and then used as both an electrochemiluminescence (ECL) emitter and a reductant to produce gold nanoparticles (Au-N-GQDs) on their surface without using any reagent. In order to avoid resonance energy transfer, the Au-N-GQDs were stabilized with chitosan. Transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), UV-vis spectroscopy (UV-vis) and ECL methods were used to characterize the nanocomposite. The materials was placed on a glassy carbon electrode (GCE), and the ECL signals are found to be strongly quenched by hydrogen peroxide that is enzymatically produced by oxidation of glucose. With the applied typical potential of −1.7 V, the ECL of the Au-N-GQDs modified GCE decreases linearly in the 10 nM to 5.0 μM glucose concentration range, and the lower detection limit is 3.3 nM. The influence of H2O2 to the signal has been discussed and a possible mechanism has been presented.