Photodynamic-Assisted Electrochemiluminescence Enhancement toward Advanced BODIPY for Precision Diagnosis of Parkinson.

Nowadays, signal enhancement is imperative to increase sensitivity of advanced ECL devices for expediting their promising applications in clinic. In this work, photodynamic-assisted electrochemiluminescence (PDECL) device was constructed for precision diagnosis of Parkinson, where an advanced emitter was prepared by electrostatically linking 2,6-dimethyl-8-(3-carboxyphenyl)4,4'-difluoroboradiazene (BET) with 1-butyl-3-methylimidazole tetrafluoroborate ([BMIm][BF4]). Specifically, protoporphyrin IX (PPIX) can trigger the photodynamic reaction under light irradiation with a wavelength of 450 nm to generate lots of singlet oxygen (1O2), showing a 2.43-fold magnification in the ECL responses. Then, the aptamer (Apt) was assembled on the functional BET-[BMIm] for constructing a "signal off" ECL biosensor. Later on, the PPIX was embedded into the G-quadruplex (G4) of the Apt to magnify the ECL signals for bioanalysis of α-synuclein (α-syn) under light excitation. In the optimized surroundings, the resulting PDECL sensor has a broad linear range of 100.0 aM ∼ 10.0 fM and a low limit of detection (LOD) of 63 aM, coupled by differentiating Parkinson patients from normal individuals according to the receiver operating characteristic (ROC) curve analysis of actual blood samples. Such research holds great promise for synthesis of other advanced luminophores, combined with achieving an early clinical diagnosis.

The dual ECL signal enhancement strategy of Pd nanoparticles attached covalent organic frameworks and exonuclease cycling reaction for the ultrasensitive detection of progesterone.

Nowadays, novel and efficient signal amplification strategy in electrochemiluminescence (ECL) platform is urgently needed to enhance the sensitivity of biosensor. In this work, the dual ECL signal enhancement strategy was constructed by the interactions of Pd nanoparticles attached covalent organic frameworks (Pd NPs@COFs) with tris (bipyridine) ruthenium (RuP) and Exonuclease III (Exo.III) cycle reaction. Within this strategy, the COFs composite was generated from the covalent reaction between 2-nitro-1,4-phenylenediamine (NPD) and trialdehyde phloroglucinol (Tp), and then animated by glutamate (Glu) to attach the Pd NPs. Next, the "signal on" ECL biosensor was constructed by the coordination assembly of thiolation capture DNA (cDNA) onto the Pd NPs@COFs modified electrode. After the aptamer recognition of progesterone (P4) with hairpin DNA 1 (HP1), the Exo. III cycle reaction was initiated with HP2 to generate free DNA, which hybridized with cDNA to form double-stranded DNA (dsDNA). For that, the RuP was embedded into the groove of dsDNA and achieved the ultrasensitive detection of P4 with a lower limit of detection (LOD) down to 0.45 pM, as well as the excellent selectivity and stability. This work expands the COFs-based materials application in ECL signal amplification and valuable DNA cyclic reaction in biochemical testing field.

Palladium nanospheres-embedded metal-organic frameworks to enhance the ECL efficiency of 2,6-dimethyl-8-(3-carboxyphenyl)4,4'-difluoroboradiazene in aqueous solution for ultrasensitive Cu2+ detection.

Nowadays, organic emitters suffer from insufficient electrochemiluminescence (ECL) efficiency in aqueous solutions, and their practical applications are severely restricted in the bio-sensing field. In this work, palladium nanospheres-embedded metal-organic frameworks (Pd@MOFs) were exploited to enhance the ECL efficiency of 2,6-dimethyl-8-(3-carboxyphenyl)4,4'-difluoroboradiazene (BET) prepared by a one-pot method in aqueous environment. First, the Pd@MOFs were generated via in situ reduction of Pd nanospheres anchored onto the MOFs, and fabricated by orderly coordination of palladium chloride (PdCl2) with 1,2,4,5-benzenetetramine (BTA) tetrahydrochloride. Then, the influence of protons on the ECL response of BET was studied in detail to obtain stronger ECL emission using potassium persulfate (K2S2O8) as co-reactant in aqueous environment. As a result, a 1.47-fold ECL efficiency enlargement of BET/K2S2O8 was harvested at the Pd@MOFs/GCE, where Ru(bpy)32+ behaved as a standard. Based on the fact that the ECL signals of the BET-covered Pd@MOFs modified glassy carbon electrode (simplified as BET/Pd@MOFs/GCE) can be quenched by Cu2+, the as-built ECL sensor showed a wide linear range (1.0-100.0 pM) and a limit of detection (LOD) as low as 0.12 pM. Hence, such research offers huge potential to promote the development of organic emitters in ECL biosensors and environmental monitoring.

Self-enhanced Electrochemiluminescence Luminophore Based on Pd Nanocluster-Anchored Metal Organic Frameworks via Ion Annihilation for Sensitive Cell Assay of Human Lung Cancer.

Electrochemiluminescence (ECL) has attracted significant interest in the analysis of cancer cells, where the ruthenium(II)-based emitter demonstrates urgency and feasibility to improve the ECL efficiency. In this work, the self-enhanced ECL luminophore was prepared by covalent anchoring of Pd nanoclusters on aminated metal organic frameworks (Pd NCs@MOFs), followed by linkage with bis(2,2'-bipyridine)-5-amino-1,10-phenanthroline ruthenium(II) (RuP). The resultant luminophore showed 214-fold self-magnification in the ECL efficiency over RuP alone, combined by promoting the interfacial photoelectron transfer. The enhanced mechanism through ion annihilation was critically proved by controlled experiments and density functional theory (DFT) calculations. Based on the above, a "signal off" ECL biosensor was built by assembly of tyrosine kinase 7 (PTK-7) aptamer (Apt) on the established sensing platform for analysis of human lung cancer cells (A549). The built sensor showed a lower detection limit of 8 cells mL-1, achieving the single-cell detection. This work reported a self-enhanced strategy for synthesis of advanced ECL emitters, combined by exploring the ECL biosensing devices in the single-cell analysis of cancers.

TMEM241 is a UDP-N-acetylglucosamine transporter required for M6P modification of NPC2 and cholesterol transport.

Accurate intracellular cholesterol traffic plays crucial roles. Niemann Pick type C (NPC) proteins NPC1 and NPC2, are two lysosomal cholesterol transporters that mediate the cholesterol exit from lysosomes. However, other proteins involved in this process remain poorly defined. Here, we find that the previously unannotated protein TMEM241 is required for cholesterol egressing from lysosomes through amphotericin B-based genome-wide CRISPR-Cas9 KO screening. Ablation of TMEM241 caused impaired sorting of NPC2, a protein utilizes the mannose-6-phosphate (M6P) modification for lysosomal targeting, resulting in cholesterol accumulation in the lysosomes. TMEM241 is a member of solute transporters 35 nucleotide sugar transporters family and localizes on the cis-Golgi network. Our data indicate that TMEM241 transports UDP-N-acetylglucosamine (UDP-GlcNAc) into Golgi lumen and UDP-GlcNAc is used for the M6P modification of proteins including NPC2. Furthermore, Tmem241-deficient mice display cholesterol accumulation in pulmonary cells and behave pulmonary injury and hypokinesia. Taken together, we demonstrate that TMEM241 is a Golgi-localized UDP-GlcNAc transporter and loss of TMEM241 causes cholesterol accumulation in lysosomes because of the impaired M6P-dependent lysosomal targeting of NPC2.

In situ electrostatic assembly of porphyrin as enhanced PEC photosensitizer for bioassay of single HCT-116 cells via competitive reaction.

Nowadays, synthesis of novel organic photosensitizer is imperative but challenging for photoelectrochemical (PEC) assay in analytical and biomedical fields. In this work, the PEC responses enhanced about 4.3 folds after in situ electrostatic assembly of 1-butyl-3-methylimidazole tetrafluoroborate ([BIm][BF4]) on meso-tetra (4-carboxyphenyl) porphine (TP), which was first covalently linked with NH2 modified indium tin oxide electrode ([BIm]+--TP-NH2-ITO). Moreover, the [BIm]+--TP-NH2-ITO showed a much larger photocurrent in a water/dimethyl sulfoxide (DMSO) binary solvent with a water fraction (fw) of 90%, which displayed 6.7-fold increase over that in pure DMSO, coupled by discussing the PEC enhanced mechanism in detail. Then, the PEC signals were sharply quenched via a competitive reaction between magnetic bead linked dsDNA (i.e., initial hybridization of aptamer DNA with linking DNA) and HCT-116 cells (closely associated with CRC), where the liberated L-DNA stripped the [BIm]+ from [BIm]+--TP-NH2-ITO. The PEC detection strategy exhibited a wider linear range (30 ∼ 3 × 105 cells mL-1) and a lower limit of detection (6 cells mL-1), achieving single-cell bioanalysis even in diluted human serum sample. The in situ assembly strategy offers a valuable biosensing platform to amplify the PEC signals with advanced organic photosensitizer for early diagnosis of tumors.

Hydrogen Bond Organic Frameworks as Radical Reactors for Enhancement in ECL Efficiency and Their Ultrasensitive Biosensing.

Nowadays, electrochemiluminescence (ECL) efficiency of an organic emitter is closely related with its potential applications in food safety and environmental monitoring fields. In this work, 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (TATB) was self-assembled to form hydrogen bond organic frameworks (HOFs), which worked as ideal reactors to generate highly active oxygen-containing radicals, followed by linking with isoluminol (ILu) via amide bond (termed ILu-HOFs). After covalent assembly with aminated indium-tin oxide electrode (labeled NH2-ITO), the ECL efficiency of the ILu-HOFs NH2-ITO showed about a 23.4-time increase over that of ILu itself in the presence of H2O2. Meanwhile, the enhanced ECL mechanism was mainly studied by electron paramagnetic resonance, theoretical calculation, and electrochemistry. On the above foundation, an aptamer "sandwich" ECL biosensor was constructed for detecting isocarbophos (ICP) via in situ elimination of H2O2 with catalase-linked palladium nanocubes (CAT-Pd NCs). The as-built sensor showed a broad linear range (1 pM to 100 nM) and a low limit of detection (LOD) down to 0.4 pM, coupled with efficient assays of ICP in lake water and cucumber juice samples. This strategy provides an effective way for the synthesis of advanced ECL emitter, coupled by showing promising applications in environmental and food analysis.

Covalent organic framework linked with amination luminol derivative as enhanced ECL luminophore for ultrasensitive analysis of cytochrome c.

Cytochrome c (cyt c) plays a critical role in mitochondrial respiratory chain, whose absence is detrimental to electron transport and reduce adenosine triphosphate. For ultrasensitive detection of cyt c, sheet-like covalent organic frameworks (COFs) were prepared by orderly accumulation of 1,3,5-benzenetricarboxaldehyde (BTA) and p-phenylenediamine (PDA), and further grafted with N-(4-aminobutyl)-N-ethylisoluminol (ABEI) - an electrochemiluminescence (ECL) emitter. Specifically, the morphology and structure of the COFs-ABEI were mainly characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, and X-ray photoelectron spectroscopy (XPS). In parallel, the optical properties of the emitter were certified by UV-vis absorbance spectroscopy, Fourier infrared spectroscopy (FTIR), fluorescence (FL), and ECL measurements, showing 2.25-time enhanced ECL efficiency over pure ABEI, coupled by illustrating the interfacial electron transport mechanism. On the above foundation, a label-free "signal off" ECL biosensor was constructed by virtue of the specific immune recognition between the aptamer of the target cyt c with its capture DNA (cDNA) anchored on the biosensing platform, exhibiting a wider linear range of 1.00 fg mL-1-0.10 ng mL-1 (R2 = 0.998) and a lower limit of detection (LOD) down to 0.73 fg mL-1. This work offers some constructive guidelines for sensitive bioassays of disease-related biomarkers in the clinical field.

Heterometallic nanomaterials: activity modulation, sensing, imaging and therapy.

Heterometallic nanomaterials (HMNMs) display superior physicochemical properties and stability to monometallic counterparts, accompanied by wider applications in the fields of catalysis, sensing, imaging, and therapy due to synergistic effects between multi-metals in HMNMs. So far, most reviews have mainly concentrated on introduction of their preparation approaches, morphology control and applications in catalysis, assay of heavy metal ions, and antimicrobial activity. Therefore, it is very important to summarize the latest investigations of activity modulation of HMNMs and their recent applications in sensing, imaging and therapy. Taking the above into consideration, we briefly underline appealing chemical/physical properties of HMNMs chiefly tailored through the sizes, shapes, compositions, structures and surface modification. Then, we particularly emphasize their widespread applications in sensing of targets (e.g. metal ions, small molecules, proteins, nucleic acids, and cancer cells), imaging (frequently involving photoluminescence, fluorescence, Raman, electrochemiluminescence, magnetic resonance, X-ray computed tomography, photoacoustic imaging, etc.), and therapy (e.g. radiotherapy, chemotherapy, photothermal therapy, photodynamic therapy, and chemodynamic therapy). Finally, we present an outlook on their forthcoming directions. This timely review would be of great significance for attracting researchers from different disciplines in developing novel HMNMs.

Novel Aggregation-Enhanced PEC Photosensitizer Based on Electrostatic Linkage of Ionic Liquid with Protoporphyrin IX for Ultrasensitive Detection of Molt-4 Cells.

Nowadays, aggregation quenching of most organic photosensitizers in aqueous media seriously restricts analytical and biomedical applications of photoelectrochemical (PEC) sensors. In this work, an aggregation-enhanced PEC photosensitizer was prepared by electrostatically bonding protoporphyrin IX (PPIX) with an ionic liquid of 1-butyl-3-methylimidazole tetrafluoroborate ([BMIm][BF4]), termed as PPIX-[BMIm] for clarity. The resultant PPIX-[BMIm] showed weak photocurrent in pure dimethyl sulfoxide (DMSO, good solvent), while the PEC signals displayed a 44.1-fold enhancement in a water (poor solvent)/DMSO binary solvent with a water fraction (fw) of 90%. Such PEC-enhanced mechanism was critically studied by electrochemistry and density functional theory (DFT) calculation in some detail. Afterward, a label-free PEC cytosensor was built for ultrasensitive bioassay of acute lymphoblastic leukemia (molt-4) cells by electrodepositing Au nanoparticles (Au NPs) on the PPIX-[BMIm] aggregates and sequential assembly of protein tyrosine kinase (PTK) aptamer DNA (aptDNA). The resultant cytosensor showed a wide linear range (300 to 3 × 105 cells mL-1) with a limit of detection (LOD) as low as 63 cells mL-1. The aggregation-enhanced PEC performance offers a valuable and practical pathway for synthesis of advanced organic photosensitizer to explore its PEC applications in early diagnosis of tumors.

Hydrogen Bond Organic Frameworks as a Novel Electrochemiluminescence Luminophore: Simple Synthesis and Ultrasensitive Biosensing.

Nowadays, continuous efforts have been devoted to searching highly efficient electrochemiluminescence (ECL) emitters for applications in clinical diagnosis and food safety. In this work, triazinyl-based hydrogen bond organic frameworks (Tr-HOFs) were synthesized by N···H hydrogen bond self-assembly aggregation, where 6,6'-(1,4-phenylene)bis(1,3,5-triazine-2,4-diamine) (phenyDAT) was prepared via the cyclization reaction and behaved as a novel ligand. Impressively, the resulting Tr-HOFs showed strong ECL responses with highly enhanced ECL efficiency (21.3%) relative to the Ru(bpy)32+ standard, while phenyDAT hardly showed any ECL emission in aqueous phase. The Tr-HOFs innovatively worked as a new ECL luminophore to construct a label-free biosensor for assay of kanamycin (Kana). Specifically, the ECL response greatly weakened upon assembly of captured DNA with ferrocene (cDNA-Fc) onto the Tr-HOFs-modified electrode, while the ECL signals were adversely recovered by releasing linked DNA (L-DNA) from double-stranded DNA (dsDNA, hybridization of aptamer DNA (aptDNA) with L-DNA) due to the specific recognition of Kana with the aptDNA combined by the linkage of L-DNA and cDNA-Fc on the electrode. The as-built sensor showed a broadened linear range (1 nM-10 µM) and a limit of detection (LOD) down to 0.28 nM, which also displayed satisfactory results in the analysis of Kana in the milk and diluted human serum samples. This work offers a novel pathway to design an ECL emitter with organic molecules, holding great promise in biomedical analysis and food detection.

The enhanced photoelectrochemical platform constructed by N-doped ZnO nanopolyhedrons and porphyrin for ultrasensitive detection of brain natriuretic peptide.

Nowadays, brain natriuretic peptide (BNP-32) is fundamental to early cardiovascular clinical diagnosis, whose accurate assay is of significance by photoelectrochemistry (PEC) for the low background and high precision. Herein, a novel enhanced PEC platform was built by successive deposition of N-doped ZnO nanopolyhedra (N-ZnO NP) and protoporphyrin IX (PPIX). Specifically, the N-ZnO NP with a narrow bandgap of 2.60 eV was synthesized by direct calcination of zeolitic imidazole framework-8 (ZIF-8), and performed as the substrate to enhance the photocurrents of PPIX (as photosensitizer) whose photoelectron transfer pathway and enhanced PEC mechanism were studied in detail. Under such foundation, a label-free PEC aptasensor was developed by deposition of DNA aptamer onto the PEC platform and then ultrasensitive assay of BNP-32 based on a "signal off" model. The biosensor showed a wide linear range (1 pg mL-1- 0.1 µg mL-1) with a limit of detection (LOD) as low as 0.14 pg mL-1. This doping technique of ZnO nanomaterials provides some valuable guidelines for synthesis of advanced PEC probes in bioanalysis.

The electrochemiluminescence coreactant accelerator of metal-organic frameworks grafted with N-(aminobutyl)-N-(ethylisoluminol) for the ultrasensitive detection of chloramphenicol.

In this work, metal-organic frameworks (MOFs) are utilized as effective ECL coreactant accelerator to enhance the ECL responses of N-(aminobutyl)-N-(ethylisoluminol) (ABEI). Zn-based MOFs (MOF-Zn-1) were prepared by chelating Zn ions with melamine and thiophenedicarboxylic acid (TPDA), which observably accelerated the electrocatalytic oxidation of tripropylamine (TPA). Then, ABEI-MOF-Zn-1 as a high-performance ECL emitter was synthesized via an amide reaction between ABEI and mercaptopropionic acid (MPA) modified MOF-Zn-1. Strikingly, the ABEI-MOF-Zn-1 showed the 18-fold increase in the ECL signals relative to pure ABEI by using TPA as a coreactant. Moreover, ferrocene (Fc) as a quencher was first linked with capture DNA (cDNA), and then used to modify the ABEI-MOF-Zn-1, thereby constructing a label-free ECL biosensor. After the linkage between chloramphenicol (CAP) and aptamer DNA (aptDNA), the ECL response was definitely recovered by releasing L-DNA from double-stranded DNA (dsDNA, hybridization of aptDNA and L-DNA). The resultant sensor showed a wide linear range of 1.00 nM-0.10 mM (R2 = 0.99) and a low limit of detection (LOD) down to 0.11 nM for detecting CAP. This work developed a novel pattern to design an efficient ECL enhanced emitter, coupled by expanding its potential applications in clinical diagnosis.

Facile synthesis of porous iridium-palladium-plumbum wire-like nanonetworks with boosted catalytic performance for hydrogen evolution reaction.

Exploring advanced nanocatalysts are of importance for hydrogen evolution reaction (HER) in alkaline electrolyte (e.g. 1.0 M KOH). Herein, porous iridium-palladium-plumbum wire-like nanonetworks (IrPdPb WNNs) were prepared by a facile one-pot aqueous method with octylphenoxypolyethoxyethanol (NP-40) as the structure-director. The resultant IrPdPb WNNs exhibited superior HER performance in the alkaline electrolyte, such as ultra-low overpotential (21 mV) to drive a current density of 10 mA cm-2, small Tafel slope (66 mV dec-1), and high exchange current density (4.87 mA cm-2), surpassing commercial Pt/C. This study provides a simple strategy for synthesis of advanced multi-metallic electrocatalysts in energy storage and conversion.

A robust and efficient aqueous electrochemiluminescence emitter constructed by sulfonate porphyrin-based metal-organic frameworks and its application in ascorbic acid detection.

The robust and strong electrochemiluminescence (ECL) emission of organic emitters in an aqueous solution is crucial for expanding their applications in early diagnosis. Herein, a Zn porphyrin-based metal-organic framework ((Zn)porphMOF) was facilely obtained by chelating Zn(ii)meso-tetra (4-sulfonatophenyl) porphine (Zn-TSPP) with Zn ions, showing substantially enhanced ECL radiation with K2S2O8 as the coreactant via the "reduction-oxidation" route in aqueous media. In contrast with Zn-TSPP, (Zn)porphMOF displayed 22-fold increase in the ECL intensity because of the agglomeration effect. By virtue of the dramatic confinement towards the energy and electron transfer of ascorbic acid (AA) during the ECL process, an ultrasensitive biosensor was developed with a wide linear range (3.77 to 26.4 µM) and ultra-low detection limit of 0.29 µM at 3 times of the signal-to-noise ratio (3S/N). This work offers a feasible avenue to harvest the steady and boosted ECL responses of organic molecules in aqueous media, also greatly expanding the MOF applications in bioanalysis.

Construction of efficient "on-off-on" fluorescence aptasensor for ultrasensitive detection of prostate specific antigen via covalent energy transfer between g-C3N4 quantum dots and palladium triangular plates.

Development of ultra-sensitive and high specific aptasensors is important for early diagnosis of prostate cancer. Herein, ultrasensitive detection of prostate specific antigen (PSA) aptasensor was realized based on the "on-off-on" model via fluorescence (FL) covalent energy transfer between g-C3N4 quantum dot (g-CNQDs) and palladium triangular plates (Pd TPs). Specifically, the Pd TPs were primarily linked with PSA aptamer (PA) as the reporter probe, followed by attaching them onto the g-CNQDs surfaces, causing the highly enlarged FL quenching rate (ca. 75%). After the introduction of PSA, the FL intensities recovered again because of the distinctively stronger affinity of PA to PSA than that of g-CNQDs. The bond of pyridine N with Pd was identified as efficient energy transfer pathway through the X-ray photoelectron spectroscopy (XPS) and FL measurements. The surface plasmon resonance (SPR) experiments certified the remarkably different affinity of PA towards g-CNQDs and PSA. The as-constructed FL aptasensor can accurately quantify PSA with wide linear range of 10 pg mL-1-50 ng mL-1 and ultra-low limit of detection (LOD, 4.2 pg mL-1), indicating the promising applications in clinical assay and biological detection.

The mimetic assembly of cobalt prot-porphyrin with cyclodextrin dimer and its application for H2O2 detection.

A biomimetic assembly of per-O-methylated-cyclodextrin dimer with cobalt proto-porphyrin (CoIII-PPIX@Py2CD) was achieved via covalent linkage between CoIII of CoIII-PPIX and pyridine N of Py2CD (primarily synthesized by the acyl chlorination reaction of two ß-CDs monomers with 3,5-bis (bromomethyl) pyridine). Ultraviolet-visible (UV-vis) and circular dichroism (CD) absorption spectroscopy, and NMR hydrogen spectroscopy (H1-NMR) were adopted to carefully characterize the structure of Py2CD and its functional assembly with CoIII-PPIX. X-ray photoelectron spectroscopy (XPS) was employed to affirm the binding of the as-obtained CoIII-PPIX@Py2CD, whose electrochemical kinetics were extensively studied to validate the feasibility in the catalytic reduction of hydrogen peroxide (H2O2). The developed sensor displayed the wide linear range for H2O2 detection and the low detection limit of 2.47 × 10-7 M. This work sheds some constructive lights on rational design and synthesis of preeminently biomimic carrier and high cost-effectiveness catalyst for (bio)analytical applications.

Highly Enhanced Electrochemiluminescence Luminophore Generated by Zeolitic Imidazole Framework-8-Linked Porphyrin and Its Application for Thrombin Detection.

Novel and distinct enhancement in electrochemiluminescence (ECL) signals of advanced organic luminophores are of importance for expanding their applications in early diagnosis. This work reported the construction of an ultrasensitive label-free ECL aptasensor for thrombin (TB) detection by grafting zinc proto-porphyrin IX (ZnP) onto an aminated zeolitic imidazole framework-8 (defined as ZnP-NH-ZIF-8 for clarity) as the luminophore. The structure and optical properties of the resulting ZnP-NH-ZIF-8 were carefully characterized. For that, there appeared to be weak ECL radiation for ZnP in dichloromethane (DCM) containing tetra-n-butylammonium perchlorate (TBAP) because of the as-formed singlet-state oxygen via the "reduction-oxidation" route. More notably, the ECL signals display 153-times enhancement for ZnP-NH-ZIF-8, thanks to the excellent catalytic kinetics for the oxygen reduction reaction (ORR). By virtue of the specific interactions of the TB aptamer (TBA) with the TB protein and the highly efficient catalysis of the ZnP-NH-ZIF-8 for ORR, the as-prepared aptasensor showed a wider linear range (0.1 fM∼1 pM) and a lower detection limit (ca. 58.6 aM). This work provides some useful guidelines for synthesis of an advanced organic luminophore with largely boosted ECL signals in ultrasensitive analysis and clinical diagnosis.

Simple one-pot aqueous synthesis of 3D superstructured PtCoCuPd alloyed tripods with hierarchical branches for ultrasensitive immunoassay of cardiac troponin I.

By integrating the amplified electrochemical signals and effective capture of antibodies together, advanced multimetallic superstructured nanocrystals endow label-free immunosensors promising applications in early diagnosis and monitoring of diseases. Herein, four-metallic PtCoCuPd hierarchical branch-like tripods (HBTPs) were directly synthesized by a green one-pot aqueous method without any seed or organic solvent involved, which were applied to construct a novel label-free immunosensor for detecting cardiac troponin I (cTnI). The specific hierarchical micro/nanostructures greatly improved the immobilization of antibodies and enhanced the catalytic activity for K3Fe(CN)6, which would effectively amplify the electrochemical signals, thereby improving the detection sensitivity. Under the optimal conditions, the as-developed immunosensor exhibited a wide linear range (0.001-100.0 ng mL-1) and a low detection limit (0.2 pg mL-1, S/N = 3) for the assay of cTnI. The immunosensor provides a powerful platform for quantitative detection of cTnI, which can be explored to detect other tumor markers in actual sample analysis.

Three dimensional sea-urchin-like PdAuCu nanocrystals/ferrocene-grafted-polylysine as an efficient probe to amplify the electrochemical signals for ultrasensitive immunoassay of carcinoembryonic antigen.

A novel sandwich-like immunosensor was efficiently fabricated for detection of carcinoembryonic antigen (CEA) with three dimensional sea-urchin-like PdAuCu nanocrystals (PdAuCu NCs)/ferrocene-grafted-polylysine (Fc-g-PLL) as the label of secondary antibodies (Ab2) and Au nanoparticles (Au NPs) as the substrate material. Herein, PdAuCu NCs were directly synthesized with polyethylene oxide (PEO) as a growth-directing agent by a facile one-step aqueous method without any organic solvent. Meanwhile, Fc-g-PLL was obtained by covalent linkage of Fc with PLL via Schiff-base reaction. The well-dispersed PdAuCu NCs by Fc-g-PLL have the enlarged surface area, enhanced catalytic properties and superior biocompatibility to amplify the current signals. The resultant immunosensor shows linear relationship of the electrochemical responses with the CEA concentrations within a broader linear range (0.001-100.0 ng mL-1) and a lower detection limit (0.23 pg mL-1, S/N = 3). Furthermore, the immunosensor was explored for practical assay of CEA in human serum samples with accredited results. The novel immunoassay provides a feasible platform for early medical diagnosis.