Straightforward Synthesis of Alkyl Fluorides via Visible-Light-Induced Hydromono- and Difluoroalkylations of Alkenes with α-Fluoro Carboxylic Acids.

We herein report the first visible-light-induced hydromono- and difluoroalkylations of alkenes with inexpensive and easily accessible α-fluoro carboxylic acids. This metal-free protocol exhibits mild conditions, high efficiency, and excellent functional-group tolerance, providing a straightforward approach to mono- and difluoroalkylated alkanes. Moreover, the fluorine effect on the hydrofluoroalkylation reaction is discussed in detail.

Silver-catalyzed monofluoroalkylation of heteroarenes with α-fluorocarboxylic acids: an insight into the solvent effect.

A mild and efficient method for direct C-H monofluoroalkylation of heteroarenes with easily accessible and inexpensive α-fluorocarboxylic acids has been developed. This silver-catalyzed reaction affords mono- and bis-monofluoroalkylated heteroarenes in good yields under mild conditions, and the solvent effect on the monofluoroalkylation reaction is discussed in detail.

Ligand-Regulated Palladium-Catalyzed Regiodivergent Hydroarylation of the Distal Double Bond of Allenamides with Aryl Boronic Acid.

The ligand-regulated regiodivergent hydroarylation of the distal double bond of allenamides with aryl boronic acid was achieved in the presence of palladium(II) catalysts, delivering a variety of functionalized enamide with excellent E selectivity and Markovnikov/anti-Markovnikov selectivity. Two possible coordination intermediates were proposed to be responsible for the regiodivergent hydroarylation: (1) The coordination Intermediate I, which was proposed to be formed through the coordination of MeCN, distal double bond, phenyl to palladium, led to the aryl group away from the Intermediate I, inducing excellent E selectivity and anti-Markovnikov selectivity. (2) A switch of regioselectivity to 1,2-Markovnikov hydroarylation was obtained using bidentate phosphine ligand (dppf or Xantphos). The formed coordination Intermediate II led to the N-tether away from the Intermediate II and at the trans position of aryl, resulting in excellent E selectivity and Markovnikov selectivity. Meanwhile, tentative investigation on the mechanism proved that the hydron source of this hydroarylation is more likely to be boronic acid. The transmetallation between aryl boronic acid and palladium catalyst was the initial step of this transformation.

Palladium/Norbornene Catalyzed ortho Amination/Cyclization of Aryl Iodide: Process to 3-Methyl-indole Derivates and Controllable Reductive Elimination against the Second Amination.

A palladium/norbornene cooperative catalyzed selective C-H bond amination of aryl iodides was explored, providing an efficient tool for constructing benzocyclic molecules. When ortho-substituted iodobenzene was involved, the C-H bond amination and following Heck cyclization efficiently delivered a 3-methyl-indole scaffold. On the other hand, we realized the controllable synthesis of monoaminated benzo-cyclobutanyl scaffold. The possible coordination of an installed terminal alkenyl group with palladium and steric hindrance were proposed to be responsible for the monoamination selectivity.

Simultaneous electrochemical determination of two hepatitis B antigens using graphene-SnO2 hybridized with sea urchin-like bimetallic nanoparticles.

The hepatitis B virus (HBV) can cause chronic hepatitis and hepatocellular carcinoma. Hepatitis B surface antigen (HBs-Ag) and Hepatitis B e-antigen (HBe-Ag) are key markers for the diagnosis of HBV. In this study, electrodeposited gold was used as a sensing platform. Three-dimensional (3D) SnO2-loaded graphene sheets functionalized by Thionine (Thi) and ferrocene (Fc) and hybridized by sea urchin-like bimetallic nanoparticles (GS-SnO2-BMNPs) were used as redox probes for labeling antibodies to fabricate sandwich-type immunosensors for the simultaneous determination of HBs-Ag and HBe-Ag. The bimetallic nanoparticles, gold hybrid platinum nanoparticles (Au@Pt) and L-cysteine-connected gold-silver nanoparticles (Ag-cys-Au), have large electroactive surface areas. They were prepared by an efficient and economical method. Additionally, the sea urchin morphology accelerates spatial utilization, thus increasing the number of combination sites. Therefore, the immune probe can load a mass of signal source molecules (Thi and Fc). Furthermore, GS-SnO2-BMNPs (GS-SnO2-Au@Pt and GS-SnO2-Ag-cys-Au) with excellent electrical conductivity and bimetallic synergy can enhance the square wave voltammetry (SWV) signal. SWV was used to record the electrochemical signal by scanning the potential from - 0.6 to 0.6 V (vs. SCE). The signal peaks resulted from the reduction reaction of Thi and Fc, and two signal peaks were completely separate. The peak position and current intensity reflect the identity and level of the corresponding antigens. Therefore, the simultaneous detection of two viral biomarkers was achieved by the proposed immunosensor. The fabricated immunosensor showed a linear concentration range for HBs-Ag (0.01-100 ng·mL-1) and HBe-Ag (0.01-100 ng·mL-1), with detection limits for HBs-Ag and HBe-Ag of  4.67 pg·mL-1 and 4.68 pg·mL-1, respectively.  The RSD of HBs-Ag ranged between 2.0 and 4.4%and the recovery was in the range 98.7 to 99.4%. For  HBe-Ag the RSD  was between 2.6 and 3.3% andrecoveries  in the range 99.2 to 100.5% were obtained.

A sandwich-type electrochemical immunosensor based on Au@Pd nanodendrite functionalized MoO2 nanosheet for highly sensitive detection of HBsAg.

In this work, a sandwich-type electrochemical immunosensor was fabricated to the effective detection of hepatitis B surface antigen (HBsAg). The designed electrochemical immunosensor was based on Au core and Pd shell nanodendrites loaded on amino functionalized molybdenum dioxide nanosheets (Au@Pd NDS/NH2-MoO2 NSs) as the secondary antibody (Ab2) label and silver nanoparticles were loaded by electrodeposited (D-Ag NPs) on the surface of electrode as the platform. Because of the synergistic effect and abundant catalytic activity sites provided by surface dendrite structure, Au@Pd NDs were more effective than single gold and palladium nanoparticles in catalytic reduction of hydrogen peroxide (H2O2). MoO2 had the good catalytic capacity for reduction of H2O2 and favourable electrical conductivity. Hence, the obtained Au@Pd NDS/NH2-MoO2 NSs were more effective than Au@Pd NDs and NH2-MoO2 NSs in catalytic reduction of hydrogen peroxide attribute to a synergistic effect. Also, Ag NPs with admirable electrical conductivity and biocompatibility were used as sensing platforms and primary antibodies (Ab1) carriers, which can accelerate the electron transfer and improve the sensitivity of the immunosensor. Here, the proposed electrochemical immunosensor offered a wide linear interval from 10 fg mL-1 to 100 ng mL-1 and the lower limit of detection of 3.3 fg mL-1 (S/N = 3) for detection of HBsAg under optimal experimental conditions. Furthermore, the accuracy of the actual serum sample analysis was satisfactory, which showed that the electrochemical immunosensor possessed a good application prospect in clinical detection.

Correction: Pd-Catalyzed oxidative isomerization of propargylic acetates: highly efficient access to α-acetoxyenones via alkenyl Csp2-O bond-forming reductive elimination from PdIV.

Correction for 'Pd-Catalyzed oxidative isomerization of propargylic acetates: highly efficient access to α-acetoxyenones via alkenyl Csp2-O bond-forming reductive elimination from PdIV' by Jun Li et al., Chem. Commun., 2016, 52, 10644-10647, DOI: 10.1039/C6CC04463H.

Nickel-Catalyzed Reductive Aryl Thiocarbonylation of Alkene via Thioester Group Transfer Strategy.

Herein reported is a nickel-catalyzed reductive aryl thiocarbonylation of alkene via thioester group transfer strategy by using simple and readily available thioesters. In contrast to traditional activation of weaker C(acyl)-S bond, the C(acyl)-C bond of thioester was selectively cleaved to enable this reaction under mild conditions. Furthermore, this approach features operational simplicity and broad substrate scope, providing a complementary and practical route for thioester synthesis without requiring toxic thiol or CO gas.

Self-assembly of a cobalt(II)-based metal-organic framework as an effective water-splitting heterogeneous catalyst for light-driven hydrogen production.

The solar photocatalysis of water splitting represents a significant branch of enzymatic simulation by efficient chemical conversion and the generation of hydrogen as green energy provides a feasible way for the replacement of fossil fuels to solve energy and environmental issues. We report herein the self-assembly of a CoII-based metal-organic framework (MOF) constructed from 4,4',4'',4'''-(ethene-1,1,2,2-tetrayl)tetrabenzoic acid [or tetrakis(4-carboxyphenyl)ethylene, H4TCPE] and 4,4'-bipyridyl (bpy) as four-point- and two-point-connected nodes, respectively. This material, namely, poly[(µ-4,4'-bipyridyl)[µ8-4,4',4'',4'''-(ethene-1,1,2,2-tetrayl)tetrabenzoato]cobalt(II)], [Co(C30H16O8)(C10H8N2)]n, crystallized as dark-red block-shaped crystals with high crystallinity and was fully characterized by single-crystal X-ray diffraction, PXRD, IR, solid-state UV-Vis and cyclic voltammetry (CV) measurements. The redox-active CoII atoms in the structure could be used as the catalytic sites for hydrogen production via water splitting. The application of this new MOF as a heterogeneous catalyst for light-driven H2 production has been explored in a three-component system with fluorescein as photosensitizer and trimethylamine as the sacrificial electron donor, and the initial volume of H2 production is about 360 µmol after 12 h irradiation.

An enzyme-free immunosensor for sensitive determination of procalcitonin using NiFe PBA nanocubes@TB as the sensing matrix.

In this work, a label-free electrochemical immunosensor was developed for the detection of procalcitonin (PCT), using toluidine blue functionalized NiFe Prussian-blue analog nanocubes (NiFe PBA nanocubes@TB) as a signal amplifier. NiFe PBA nanocubes was synthesized by a simple and efficient self-templating method in this work. NiFe PBA nanocubes with open-framework construction not only provides a larger specific area to load a mass of antibodies but produces an excellent signal without adding extra reaction reagent. Besides, the electrochemical performance of NiFe PBA nanocubes can be enhanced after functionalized with TB. The developed immunosensor exhibited favorable performance for PCT detection with a linear range from 0.001 to 25 ng mL-1 and a detection limit of 3 × 10-4 ng mL-1. Moreover, the immunosensor with acceptable reproducibility, selectivity, and stability may provide a new strategy in the clinical detection of PCT.

A Signal Amplification Strategy of CuPtRh CNB-Embedded Ammoniated Ti3C2 MXene for Detecting Cardiac Troponin I by a Sandwich-Type Electrochemical Immunosensor.

An early diagnosis of cardiovascular disease is of great importance to patients. Herein, a sandwich-type immunosensor for the detection of cardiac troponin I (cTnI) is prepared by using gold nanoparticles (Au NPs) and a composite (CuPtRh CNBs/NH2-Ti3C2) of trimetallic hollow CuPtRh cubic nanobox (CNB)-embedded few-layer ultrathin ammoniated MXene (NH2-Ti3C2). The embedding of the CuPtRh CNBs into NH2-Ti3C2 successfully prevents the restacking of NH2-Ti3C2 and offers more active sites for catalytic H2O2 reduction, which can effectively increase the current signal of the immunosensor. The designed sandwich-type electrochemical immunosensor for detection cTnI has a detection range of 25 fg mL-1 to 100 ng mL-1, and the detection limit is 8.3 fg mL-1 (S/N = 3). Moreover, the immunosensor also demonstrates high sensitivity, acceptable reproducibility, and good stability. More importantly, the designed system offers a direction for early clinical testing of cardiovascular and cerebrovascular diseases.

Electrochemical Immunosensors for Sensitive Detection of Neuron-Specific Enolase Based on Small-Size Trimetallic Au@Pd

Medically, neuron-specific enolase (NSE) as a specific tumor marker has become an important indicator to diagnose small-cell lung carcinoma. In this study, a sandwich-type electrochemical immunosensor was designed to determine NSE sensitively. Au nanoparticle (Au NP)-embedded zinc-based metal-organic frameworks (Au@MOFs) were prepared as the substrate materials to modify the electrode and immobilize the primary antibody (Ab1). The Au@MOFs with the free amino groups on the MOF surface could effectively increase the immobilization amount of Ab1 through covalent linkage. Simultaneously, the embedding of Au NPs improved the conductivity of MOFs and accelerated interface electron transfer. Sub-30 nm trimetallic Au@Pd^Pt nanocubes (Au@Pd^Pt NCs) loaded onto ultrathin MnO2 nanosheets (MnO2 UNs/Au@Pd^Pt NCs) acted as the labels of secondary antibodies. The small-size Au@Pd^Pt NCs enhanced atomic utilization efficiency and offered more catalytic active sites. The MnO2 UNs with high external surface areas could improve the dispersion of Au@Pd^Pt NCs. The MnO2 UNs/Au@Pd^Pt NCs could catalyze the H2O2 reduction and promote the oxidation of hydroquinone to quinone effectively because of their synergistic effect; thus, the generated quinone achieved amplification of the highly reductive peak current. Furthermore, under the optimal conditions, the immunosensor exhibited a low detection limit (4.17 fg/mL) and broad linear range (10 fg/mL to 100 ng/mL). The results were satisfactory for NSE detection in human serum samples, implying that the presented method had great application potential in clinical bioanalysis.

The preparation of hollow AgPt@Pt core-shell nanoparticles loaded on polypyrrole nanosheet modified electrode and its application in immunosensor.

The designed synthesis of efficient materials can significantly enhance the performance of electrochemical immunoassay in the detection of diseases, pesticide residues and environmental pollutants. The hollow AgPt@Pt core-shell nanoparticles (AgPt@Pt HNs) have exhibited high catalytic efficiency to the hydrogen peroxide (H2O2) reduction for its high mass activity from their hollow structure. Their limitation of instability can be overcome by loading on polypyrrole nanosheet (PPy NS). Besides, PPy NS exhibits good conductivity, and there exists environmentally-friendly method for its synthetic. Thus, AgPt@Pt HNs loaded on PPy NS (AgPt@Pt HNs/PPy NS) exhibits high catalytic efficiency to the reduction of H2O2 and good stability. Furthermore, the quick electron transfer of AgPt@Pt HNs/PPy NS modified glassy carbon electrode has been evidenced by the finding that the large constant of apparent electron transfer rate has also enlarged the current signal when the amount of electron is invariant. The modified electrode has fabricated a label-free amperometric immunosensor to detect sensitively prostate-specific antigen (PSA) with H2O2 as the electroactive material. The immunosensor in hollow core-shell nanosheet structure exhibiting good detection performance of PSA shows its promising applications in the clinical diagnosis.

Mulberry-like Au@PtPd porous nanorods composites as signal amplifiers for sensitive detection of CEA.

Effective detection of cancer biomarkers plays a crucial role in the prevention of early cancer. Here, a sandwich-type electrochemical immunosensor was successfully constructed for sensitive detection of carcinoembryonic antigen (CEA) using MoS2/CuS-Au as sensing platform and mulberry-like Au@PtPd porous nanorods (Au@PtPd MPs) as signal amplifiers. The large surface area and good biocompatibility of MoS2/CuS-Au increased the loading of primary antibody. And the good conductivity of MoS2/CuS-Au accelerated the electron transport rate of the electrode surface. Au@PtPd MPs with large specific surface area and a large number of catalytically active sites showed excellent electrocatalytic performance for hydrogen peroxide reduction. The sandwich-type immunosensor prepared by the signal amplification strategy exhibited a wide linear detection range (50 fg/mL to 100 ng/mL) and a low detection limit of 16.7 fg/mL (S/N = 3), featuring good selectivity, stability and reproducibility. Moreover, the satisfactory results in analysis of human serum samples indicated that it possessed a potential application promising in early clinical diagnoses.

Various Structural Types of Cyanide-Bridged FeIII-MnIII Bimetallic Coordination Polymers (CPs) and Polynuclear Clusters Based-on A New mer-Tricyanoiron(III)Building Block: Synthesis, Crystal Structures, and Magnetic Properties.

Four cyanide-bridged FeIII-MnIII complexes {[Fe(qxcq)(CN)3][Mn(L1)(H2O)]}[Mn(L1)(H2O)(CH3OH)](ClO4)·1.5MeOH·0.5H2O (L1 = N,N'-bis(3-methoxy-5-bromosalicylideneiminate) (2), {[Fe(qxcq)(CN)3][Mn(L2)]}2·0.5H2O (L2 = N,N'-ethylene-bis(3-ethoxysalicylideneiminate)) (3), [Fe(qxcq)(CN)3][Mn(L3)] (L3 = bis(acetylacetonato)ethylenediimine) (4), [Fe(qxcq)(CN)3][Mn(L4)]·1.5MeOH·0.5CH3CN·0.25H2O (L4 = N,N'-(1,1,2,2-tetramethylethylene)bis(salicylideneiminate)) (5), were prepared by assembling a new structurally characterized mer-tricyanoiron(III) molecular precursor (Ph4P)[Fe(qxcq)(CN)3]·0.5H2O (qxcq- = 8-(2-quinoxaline-2-carboxamido)quinoline anion) (1) and the corresponding manganese(III) Schiff base compound. Complexes 2and 3containa cyanide-bridged heterobimetallic dinuclear entity, which can be further dimerized by self-complementary H-bond interactions through the coordinated water molecule from one complex and the free O4unit from the adjacent complex. Complexes 4 and 5 area one-dimensional coordination polymer (CP) comprised of the repeated [Mn(Schiffbase)-Fe(qxcq)(CN)3] units. Complex 4 shows a linear-chain conformation with two trans-located cyano groups bridgingthe neighboring Mn units, while complex 5 is a zigzag-like 1D CP, where the two cyano groups in cis configurationfunction as bridges. In bothcomplexes 4 and 5, the inter-chain π-πstack interactions within the aromaticrings of cyanide precursor extend the 1D chain into the supermolecular 2D networks. The magnetic property has been experimentally studied and theoretically fitted over the four Fe(III)-Mn(III) complexes, revealing the antiferromagnetic interaction in complexes 2 and 4 and the unusual ferromagnetic coupling in complexes 3 and 5 between the Fe(III) ion and the Mn(III) ion bridged by the cyano group. Furthermore, the different magnetic coupling nature has been analyzed on the basis of the magneto-structure correlation of the mer-tricyanometallate-based Fe(III)-Mn(III) magnetic system.

An organocatalytic method for constructing pyrroles via the cycloisomerisation of Z-1-iodo-4-N-methylbenzenesulfonyl-1,6-enynes.

A new cycloisomerisation of Z-1-iodo-4-N-methylbenzenesulfonyl-1,6-enynes to functionalized pyrroles was realized in the presence of an organomolecule (4,4'-bis(1,1-dimethylethyl)-2,2'-bipyridine) and KOtBu. The transformations were performed efficiently to produce different kinds of functionalized pyrroles within 10 min. This is the first example of an organomolecule promoted methodology with vinyl iodides from a non-aromatic system to an aromatic system, which offers an excellent option toward establishing a new horizon for cross-coupling reactions of vinyl halides. Preliminary mechanistic studies were performed and a crude radical pathway was proposed.

A label-free immunosensor based on PtPd NCs@MoS2 nanoenzymes for hepatitis B surface antigen detection.

Nowadays, nanomaterials with enzymatic properties have aroused wide interest because of their special advantages, such as catalytic activity, simple preparation method and high stability. We introduced new nanoenzymes to a label-free electrochemical immunosensor for Hepatitis B surface antigen (HBs Ag) detection. In this study, PtPd nanocubes@MoS2 nanoenzymes (PtPd NCs@MoS2) were prepared by loading PtPd nanocubes (PtPd NCs) on molybdenum disulfide nano-sheet (MoS2) through in situ redox polymerization. The prepared nanoenzymes exhibited enhanced peroxidase-like activity than separate MoS2 and PtPd NCs. The catalytic process of PtPd NCs@MoS2 is in agreement with the Michaelis-Menten kinetic equation. PtPd NCs@MoS2 were used for sensitive detection of HBs Ag, which is ascribed to their superior peroxidase activity, good conductivity and high specific surface area and synergistic amplification for current signals. Compared with the detection limit of colorimetric method (3.3 pg/mL), the electrochemical method (10.2 fg/mL) shows a lower detection limit and a wider linear range from 32 fg/mL to 100 ng/mL, so it is more suitable for quantitative analysis of Hepatitis B. In summary, the prepared immunosensor provides a better opportunity for early diagnosis of Hepatitis B and also has further applications in biosensing and medical diagnostics.

Electrochemical immunosensor based on MoS2 NFs/Au@AgPt YNCs as signal amplification label for sensitive detection of CEA.

Medically, the dynamic change of carcinoembryonic antigen (CEA) concentration has been an important indicator for monitoring and diagnosing tumors. The sensitive and early detection of CEA plays a momentous role in the prevention and diagnosis of cancer and the evaluation of treatment efficiency. In this work, a sensitive sandwich-type electrochemical immunosensor was fabricated for the quantitative detection of CEA. The trimetallic yolk-shell Au@AgPt nanocubes (Au@AgPt YNCs) loaded on amino-functionalized MoS2 nanoflowers (MoS2 NFs/Au@AgPt YNCs) were used as the labels to conjugate with secondary antibodies. The Au@AgPt YNCs with internal space and permeable shell improved catalytic active surface area. The nanosheet-based MoS2 NFs with good catalytic activity were used as carriers to load Au@AgPt YNCs effectively. Due to the biphasic synergistic catalysis, MoS2 NFs/Au@AgPt YNCs catalyzed the reduction of H2O2 effectually to amplify the current signal. Besides, Au triangular nanoprisms (Au TNPs) were used as substrate material to increase the effective contact areas with the surface of electrode and accelerate the interface electron transfer. Under the optimal conditions, a broad linear range from 10 fg mL-1 to 100 ng mL-1 with low detection limit of 3.09 fg mL-1 (S/N = 3) for detecting CEA was obtained. Moreover, the detection results of the human serum samples were satisfactory, indicating the fabricated immunosensor had potential application values in the early clinical analysis.

An electrochemical sandwich immunosensor for cardiac troponin I by using nitrogen/sulfur co-doped graphene oxide modified with Au@Ag nanocubes as amplifiers.

A voltammetric sandwich immunoassay is described for the biomarker cardiac troponin I (cTnI). The gold nanocube-functionalized graphene oxide (AuNC/GO) is employed as a substrate to accelerate the electron transfer and to immobilize more primary antibodies. It also employs composite materials prepared from bimetallic gold/silver core-shell nanocubes and nitrogen and sulfur co-doped reduced graphene oxide as the signal amplifier. The introduction of N and S into GO enlarges the active surface and accelerates the electron transfer rate. Such unique characteristics render the material an effective support substrate to load more Au@AgNC and to immobilize an increasing number of second antibodies via Ag-N bonds. After specific binding with cTnI, the immunosensor was incubated in a labeled cTnI secondary antibody solution. The amperometric signal change is then measured at 0.34 V (vs. SCE) using o-phenylenediamine and hydrogen peroxide as an electrochemical probe. Response is linear in the concentration range from 100 fg∙mL-1 to 250 ng∙mL-1, and the detection limit is 33 fg∙mL-1. Graphical abstract Schematic presentation of cardiac troponin I (cTnI) electrochemical immunosensor based on gold nanocube-functionalized graphene oxide (AuNC/GO) as substrate material, bimetallic gold/silver core-shell nanocubes and nitrogen and sulfur co-doped reduced graphene oxide (Au@AgNC/N, S-rGO) as signal amplifier, and hydrogen peroxide (H2O2) and o-phenylenediamine (o-PD) as redox probe.

Sensitive amperometric immunosensor with improved electrocatalytic Au@Pd urchin-shaped nanostructures for human epididymis specific protein 4 antigen detection.

Sensitive detection of early ovarian cancer is imminent for women's health. Human epididymis specific protein 4 antigen (HE4 Ag), as a novel tumor marker, has good specificity and sensitivity in ovarian cancer markers, especially for the detection of early ovarian cancer. In this work, a novel and ultrasensitive sandwich-type amperometric electrochemical immunosensor was constructed using amine modified graphene supported gold nanorods (Au NRs/NH2-GS) as a sensor platform and core-shell Au@Pd urchin-shaped nanostructures (Au@Pd USs) as a label of the secondary antibodies (Ab2, Au@Pd USs-Ab2) to realize the quantitative determination of HE4 Ag. The Au NRs/NH2-GS were used for increasing the electrode surface area and effectively immobilizing primary antibodies (Ab1) due to its good water-solubility. The Au@Pd USs have special morphology with high crystal surface index and good stability, capable of loading secondary antibodies (Ab2) and providing a larger active site for the catalysis of hydrogen peroxide (H2O2). The proposed immunosensor displays excellent performance for HE4 Ag detection over the range from 1 pmol L-1 to 50 nmol L-1 with a detection limit of 0.33 pmol L-1 (signal-to-noise ratio of 3). Moreover, the designed immunosensor exhibits excellent reproducibility, selectivity, and stability, which shows great potential in clinical diagnosis.