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The purpose of this study was to achieve a specific unlocking of the butterfly effect: nanointerface-based electrochemical biosensing of adenosine triphosphate (ATP) and alkaline phosphatase (ALP). Based on the Faraday-cage concept reported first by our group, we built a new outer Helmholtz plane (OHP)-based electrochemical biosensor by using an unique nanocomposite involving three-dimensional graphene-Au nanoparticles (3D-GO-AuNPs), tetrahedral DNA nanostructures (TDNs), and separated ATP aptamers, in which methylene blue (MB) was employed as the electrochemical signal output. In this process, the prepared nanocomposites were attached favorably onto the TDN substrate electrode surface due to the interaction of ATP and its aptamer, creating a better OHP of the electrode owing to its large enough specific surface area; then a detection limit of 0.25 pM was calculated by 3δ/slope. Whereas, the hydrolysis for ATP of ALP can hinder this binding process, therefore, the biosensor could be indirectly applied for ALP analysis with a detection limit of 0.21 mU/L (3δ/slope). Since some small changes of the two targets will set off a whole series of changes in system, the OHP-extended biosensor provides a superior electrochemical platform for complex biological processes with causal relationships in clinical diagnosis and drug development, similar to the butterfly effect. [ABSTRACT FROM AUTHOR]

A ratiometric fluorescence sensor (c-CDs/Ru(bpy)32+) based on the selective recognition of chitosan carbon dots (c-CDs) on ClO− and combine with Ru(bpy)32+ was established for sensitive and visual monitoring of hypochlorite ion (ClO−). Using this nanosensor, a highly sensitive assay of ClO− in the linear range of 0.026 − 70 μM with a low detection limit (LOD) of 8.6 nM was provided by quenching the blue emission fluorescence. It is more attractive that ClO− can also be visualized by this nanosensor via evident color changes of the solution (from blue to red) under an ultraviolet (UV) lamp. In addition, since c-CDs and Ru(bpy)32+ have good water dispersibility and water solubility, respectively, the sensor can be applied to the detection of HClO in 100% aqueous solution. This is a new colorimetric and fluorescent dual-mode nanosensor with more simple preparation procedures, low cost, and excellent biocompatibility. It provides a new method for detecting ClO− and promotes the development of biosensing. [ABSTRACT FROM AUTHOR]

Sulfoxaflor residues in 14 daily foods, including rice, sorghum, chilli, cucumber, white pear, apple, egg, beef brisket, chicken breast, fish, pork liver, milk, pine nut and honey, were simultaneously determined using a modified QuEChERS and LC–MS/MS method. These foods were classified into three categories to be purified. A combination of 25 mg of octadecylsilane (C18) + 25 mg of primary and secondary amine (PSA) + 50 mg of graphitised carbon black (GCB) + 150 mg of MgSO4 was used to purify the rice, sorghum, honey, apple and white pear. A combination of 25 mg of C18 + 50 mg of PSA + 50 mg of GCB + 150 mg of MgSO4 was used to purify the chilli and cucumber. A combination of 50 mg of C18 + 25 mg of PSA + 50 mg of GCB + 150 mg of MgSO4 was used to purify the pine nuts, egg, beef brisket, chicken breast, fish, pork liver and milk. The linearity coefficient values were greater than 0.9975. The limit of detection and limit of quantification were in the ranges of 0.7‒1.8 and 2.0‒5.0 μg kg−1, respectively. Average recoveries of the sulfoxaflor at the 14 food matrices at spiking levels of 5.0, 10 and 50 μg kg−1 ranged from 74.0% to 100.8%, and the relative standard deviation ranged from 2.2% to 11.2%. This is a simple and rapid method for the determination of sulfoxaflor residues in various kinds of daily foods. [ABSTRACT FROM AUTHOR]

Fast-scan anodic stripping voltammetry (FSASV) was applied to sensitively detect Pb2+ on a mercury film electrode (MFE). The method was involved with a controlled preconcentration by accumulation of Pb2+ on the MFE followed by FSASV measurement. At the scan rate of 500 V/s, a linear relationship between the anodic stripping peak current and the logarithm of Pb2+ concentration in the solution was observed in the range from 0.1 µmol/L to 0.1 pmol/L with a detection limit of 0.1 pmol/L. The proposed method was successfully applied for the determination of Pb2+ in spiked water samples with satisfying recoveries in the range of 98.6 to 104.3%, and the corresponding relative standard deviation ranged from 3.7 to 5.5%. Therefore, FSASV is a sensitive, fast, cost-effective and simple method for the detection of Pb2+ at picomolar level and would be very promising in heavy metal determination. [ABSTRACT FROM AUTHOR]

Using the ionic salt characteristics of CsPbBr3 perovskite nanocrystals (CsPbBr3 NCs), the fluorescence wavelength of CsPbBr3−xIx NCs could be changed by the halogen exchange reaction between CsPbBr3 NCs and oleylammonium iodide (OLAM-I). Under the excitation of a 365 nm UV lamp and the increase of OLAM-I concentration, the content of iodine in CsPbBr3−xIx NCs increased, and the fluorescence emission wavelength showed a redshift from 511.6 nm to 593.4 nm, resulting in the fluorescence color change of CsPbBr3 NCs from green to orange-red. Since OLAM-I is a mild reducing agent and easily oxidized by benzoyl peroxide (BPO), a novel colorimetric sensing approach for BPO based on the fluorescence wavelength shift was established in this study. The linear relationship between the different wavelength shifts (Δλ) and the concentration of BPO (CBPO) is found to be in the range of 0 to 120 μmol L−1. The coefficient of alteration (R2) and the detection limit are 0.9933 and 0.13 μmol L−1 BPO, respectively. With this approach, the determination procedure of BPO in flour and noodle samples can be achieved in only a few minutes and exhibit high sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

A Faraday cage-type aptasensor has been developed for dual-mode detection of a common bacterial pathogen Vibrio parahaemolyticus (VP) by electrochemiluminescence (ECL) and differential pulse voltammetry (DPV), using a multi-functionalized material Pb2+-Ru-MOF@Apt2 as signal unit. The recognition aptamer Apt2 recognizes VP; specifically, ruthenium-based metal organic framework (Ru-MOF) and lead ions (Pb2+) embedded produce an ECL signal at a working potential from 0 to 1.5 V and DPV signal from − 0.3 to − 0.8 V vs. Ag/AgCl. Since Ru-MOF is a two-dimensional conductive material signal unit overlapped onto the electrode surface to form a Faraday cage-type aptasensor. Thus, electrons could be easily exchanged between electrode and signal tags without being hindered by micron-size VP, resulting in a high detection sensitivity with a detection limit of 1.7 CFU mL−1. In addition, dual-mode detection was achieved, improving the accuracy and reliability of rapid field detection. Stability and selectivity were also satisfactory. The tests of real samples indicate that this Faraday cage-type aptasensor is suited for rapid detection of VP and analog pathogens and shows great potential in food safety. [ABSTRACT FROM AUTHOR]

A method is described for combined magnetic solid phase microextraction and electrochemiluminescent (ECL) detection of the antibiotic tetracycline. A nanocomposite of type Fe3O4@SiO2@ZnO was used as the sorbent. Tetracycline has a strong affinity for Zn(II) ion and therefore is well extracted by this sorbent. The loaded sorbent can be magnetically removed. The extraction efficiency at a 1.0 μM tetracycline concentration is around 88%. Detection is based on the use of carbon nanodots that were prepared form urea and ethylenediaminetetraacetic acid as raw materials. The electrochemical probe Ru(bpy)32+ was added to generate double ECL when scanning the potential between −3.5 and + 2 V. The two ECL signals decreased with the increase of tetracycline concentration. Under optimized experimental conditions, the ratio of the two signals is linearly related to the logarithm of the tetracycline concentration in the range from 1.0 nM to 0.1 mM, with a 0.47 nM detection limit. The method was successfully applied to the determination of tetracycline in spiked milk. It exhibited good sensitivity, selectivity and accuracy due to ratiometric read-out and prior preconcentration of analyte. [ABSTRACT FROM AUTHOR]

In this study, covalent organic frameworks (COFs) were grown in situ on magnetic nitrogen-doped graphene foam (MNGF), and the resulting composite of COFs-modified MNGF (MNC) was wrapped by molecularly imprinted polymers (MNC@MIPs) for specifically capturing SAs. A magnetic solid phase extraction (MSPE) method for SAs was established using MNC@MIPs with good magnetic responsiveness. The adsorption performance of MNC@MIPs was superior to that of non-molecularly imprinted polymers (MNC@NIPs), with shorter adsorption/desorption time and higher imprinting factors. A high-efficiency SAs analytical method was developed by fusing HPLC and MNC@MIPs-based MSPE. This approach provides excellent precision, a low detection limit, and wide linearity. By analyzing fish samples, the feasibility of the approach was confirmed, with SAs recoveries and relative standard deviations in spiked samples in the ranges of 77.2–112.7 % and 2.0–7.2 %, respectively. This study demonstrated the potential use of MNC@MIPs-based MSPE for efficient extraction and quantitation of trace hazards in food. • MNC@MIPs were prepared by in situ growth method. • MNC@MIPs served as an advance absorbent for MSPE of SAs. • MNC@MIPs reveals shorter adsorption/desorption time and higher imprint factor than MNC@NIPs. • MNC@MIPs-based MSPE and HPLC were combined for sensitive analysis of SAs. [ABSTRACT FROM AUTHOR]

Schematic diagram of the microfluidic electrochemical platform and its application for enrichment, capture, and detection of exosomes. [Display omitted] • A aptasensor-based microfluidic chip was developed for detection of tumor-derived exosome (TEX). • This EpCAM-aptasensor can sensitively detect TEX in a label-free manner within 60 min. • The herringbone structure in the chip improved the capture efficiency of TEX by 7%. • LOD of this device was 1.4 × 104 particles/mL, ranging from 1.0 × 105 to 1.0 × 109 particles/mL. • TEX in serum samples can be detectable with excellent selectivity and a low RSD of 4.37%. Exosomes are cell-secreted vesicles that facilitate intercellular communication by transferring information between cells. Tumor cells release more exosomes containing tumor genetic information in low-oxygen environments, making tumor-derived exosomes (TEX) promising biomarkers. Nevertheless, developing a high-sensitivity and convenient exosome detection method remains a challenging and valuable pursuit in clinical applications. Here, we proposed a novel microfluidic chip that incorporated a microelectrode sensor modified with EpCAM, leading specifically efficient enrichment and sensitive label-free detection of TEX. The relative impedance variation from electrochemical impedance spectroscopy (EIS) of microelectrode system after capture of TEX was ultilized to quantify concentration of exosomes. The inclusion of a herringbone structure in the chip significantly enhanced the capture efficiency of TEX, enabling highly sensitive detection of TEX with a limit of detection (LOD) of 1.4 × 104 particles/mL in a wide linear range from 1.0 × 105 to 1.0 × 109 particles/mL (R2 = 0.994). For testing TEX in serum samples, this aptasensor-based platform demonstrated excellent selectivity, stability and remarkable reproducibility, with relative standard deviation (RSD) of 4.37%. The comparison of the TEXs testing with this chip showed a significant difference between lung cancer patients and healthy controls. Overall, this aptasensor-based microfluidic chip provided a precise platform for the rapid and selective detection of TEX, holding significant potential for clinical diagnosis and medical research. [ABSTRACT FROM AUTHOR]

Herein, a one-step electrochemical sensor for selective and sensitive detection of lead ion Pb2+ was developed based on an integrated probe meso-tetra(4-carboxyphenyl) porphine (TCPP)-multi-walled carbon nanotubes (MWCNTs)@Fe 3 O 4 , which is TCPP-modified magnetic multi-walled carbon nanotubes. In the integrated probe, TCPP is a porphyrin with a specific cavity structure which could selectively chelate with Pb2+, MWCNTs with good electric conductivity provide a place to load TCPP and form a specific adsorption state of Pb2+ on the electrode surface, and Fe 3 O 4 enables the rapid separation and one-step fabrication of the electrochemical sensor. Based on it, the sample pre-enrichment, separation and determination can be integrated, making the whole process very fast and simple. In addition, fast scan voltammetry (FSV) with a scan rate up to 200 V/s could be used to improve the detection sensitivity greatly, benefitting from the specific adsorption state formed. Under the optimal conditions obtained through orthogonal experiments including adsorption time, integrated probe dosage and solution pH, there was a good linear relationship between the peak current and Pb2+ concentration ranging from 2.0 × 10−4 μg L−1 to 2.0 × 10−3 μg L−1, with the limit of detection (LOD) being 6.7 × 10−5 μg L−1 (S/N = 3) i.e. 0.067 ppt. Analysis of actual water samples was successful. Therefore, being simple, fast, selective and sensitive, the one-step electrochemical sensor proposed has a good potential in practical applications. Image 1 • A selective and sensitive electrochemical sensor for the detection of sub-ppt Pb2+ was developed. • Pre-enrichment, separation and determination were one-step completed, basing on an integrated probe. • Fast scan voltammetry at scan rate of 200 V/s was used to increase the detection sensitivity. • Pb2+ was detected easily, selectively and sensitively, with a LOD 0.067 ppt. [ABSTRACT FROM AUTHOR]

This study reports the fabrication of a novel "off-on" electrochemiluminescent (ECL) aptsensor based on ECL resonance energy transfer (RET) for the detection of deoxynivalenol (DON) in wheat and corn. Ru-MOF nanosheets (Ru-MOFs) using tris (4,4′-dicarboxylic acid-2,2′-bipyridine) ruthenium(II) as organic ligands exhibited a high ECL intensity. However, in the presence of Bi 2 S 3 nanorods, the ECL intensity of Ru-MOFs was significantly quenched owing to the efficient ECL-RET system. The function of the Ru-MOFs and Bi 2 S 3 nanorods as ECL energy donors and acceptors, respectively, were thoroughly investigated. For the construction of ECL-RET based aptasensor, a complementary sequence (cDNA) was immobilized onto Bi 2 S 3 @AuNPs to improve the binding efficiency on the sulfhydryl-modified aptamer (SH-Apt), thus reducing the distance between the donors and acceptors and triggering ECL-RET. In the presence of DON, the specificity and strong binding of DON to Apt induced a drop in Bi 2 S 3 @AuNPs-cDNA on the Ru-MOFs surface, thus restoring the ECL intensity. Under optimized conditions, the ECL biosensor showed excellent linearity over the concentration range of 0.01–500 μg kg−1 DON and a low detection limit of 9 × 10−3 μg kg−1 (S/N = 3). Consequently, the proposed strategy provides an effective analytical tool for food safety detection and drug analysis. [Display omitted] • A "off-on" ECL aptsensor based on ECL-RET for the detection of DON was developed. • The ECL-RET system is composed of Ru-MOFs (energy donor) and Bi 2 S 3 (energy acceptor). • Binding of cDNA to SH-Apt reduces the distance between the donors and acceptors and triggers ECL-RET (signal off). • When DON binds to SH-Apt, Bi 2 S 3 is shed, and the Ru-MOFs gradually restore the ECL signal (signal on). • The energy donor-acceptor pair provides new ideas for developing novel ECL sensors in food safety. [ABSTRACT FROM AUTHOR]

Herein, a fast scan cyclic voltammetry (FSCV)/electrochemiluminescence (ECL) dual-mode electrochemical biosensor based on multi-functionalized two-dimensional (2D) bionanomaterials MXene@Fe 3 O 4 -APTs as the capture unit and BPNS@CuNPs-APTs as the signal unit, was designed for the detection of human circulating tumor cell (CTC) A549. In presence of A549, a Faraday cage-type electrochemical biosensor was one-step constructed by forming a complex "capture unit-A549-signal unit". A549 cells could be captured with high efficiency, and dual-mode detected with high sensitivity. Under optimal experimental conditions, the linear range of FSCV and ECL was 101–108 cells/mL, and the detection limit was 3 cells/mL. And, the stability, reproducibility and selectivity of the sensor were all satisfied. The dual-mode detection of intact CTC by electrochemical biosensor was achieved for the first time, the feasibility and reliability of which were verified by analyzing A549 in spiked and real human whole blood samples, suggesting a broad application prospect in clinical diagnosis. • Dual-mode detection of intact CTC by electrochemical biosensor is achieved first time. • Multi-functionalized 2D bionanomaterials were designed as the capture unit and the signal unit. • FSCV and ECL verifies mutually by obtaining electrical and optical signals respectively. • CTC A549 is detected with a LOD low as 3 cells/mL. [ABSTRACT FROM AUTHOR]

• A checkerboard arranged electrochemical platform is developed well. • The backbone G4 chain is formed by TdT polymeric reaction. • The branch G4 chain is generated by the continuous stacking of 16nt G-DNA. • The sensor with lots of hemin molecules can electro-catalyze H 2 O 2 reduction. • The activity of HAT p300 and TdT can be explored well by the new method. In this study, a checkerboard arranged G4 nanostructure-supported electrochemical platform is developed well for the application to unique bio-enzymes examination. Herein, we focus on the two bio-enzymes involving histone acetyltransferase (HAT) and terminal deoxynucleotidyl transferase (TdT); the former leads to the acetyl transfer of acetyl coenzyme A to the lysine residue of the substrate peptide and the latter achieves the polymeric extension of DNA without template under a unique pool of dATP and dGTP (4: 6). A complex of antibody and short DNA is introduced onto the electrode surface based on the affinity interaction between acetyl in acetylated peptide and its antibody. and used for initiating reaction. Then, TdT-yielded rich-G sequence is formed to act as the backbone of checkerboard, and subsequently free G-DNAs can be stacked continually on the backbone under Mg2+. An excellent electrocatalytic signal to H 2 O 2 emerges noticeably, which is related with the activity of HAT p300 and TdT with a low detection limit of 2.3 pM and 0.38 mU/mL, respectively. Finally, this strategy is also used successfully for the inhibitor screening and complex sample analysis, which has important implications for the advancement of HAT- and TdT-related electrochemical bioassay and drug discovery. [ABSTRACT FROM AUTHOR]

We develop a new dual-mode analytical platform for Pb2+ assay by integrating electrochemical (EC) with electro-chemiluminescent (ECL) system, and the biosensor presents excellent sensitivity/selectivity, sufficient accuracy. [Display omitted] • A DNA-guided dual-mode EC/ECL platform is constructed well. • The formation of in-situ G4 is caused by the induction of Pb2+. • Released DNAs are generated by the shear action of Pb2+ to its DNAzyme. • The co-operative dual-mode method provides the results of mutual verification. • This method with acceptable results presents great potential applications. Lead ion (Pb2+) exposure is a serious hazard to human health, and its detection is still faced with undesirable bottleneck problems (poor sensitivity/selectivity and insufficient accuracy). Herein, a new dual-mode analytical platform for Pb2+ assay is developed by integrating electrochemical (EC) with electro-chemiluminescent (ECL) system. It all starts with the shearing action of Pb2+ to Pb2+-special DNAzyme (Pb-DNAzyme), and the substrate strand is cleaved at its cleavage site to result in two pieces of DNA, which are employed separately to construct the expected dual-mode biosensor. Interestingly, for EC mode, the Pb2+ act as not only the target but also the inducing factor of the formation of in-situ G4 nanostructure, and the SWV technique is taken to achieve the signal output of the stacked crystal violet molecules. Furtherly, the other released DNAs can be captured by the three handing sides of DNA nano-prism, and trigger subsequently the opening of DNA hybridization chain reaction; then the designed free three bases can bring about TdT polymeric reaction; finally, by taking advantage of DNA nanoprobe, the dual-mode biosensor is developed successfully with the detection limit of 3.6 pM (EC) or 0.23 pM (ECL) (3δ/slope), which is much lower than the previous reports. This co-operative dual-mode method is also investigated for the analysis of Pb2+ in the serum and lake water samples with acceptable results, presenting great potential applications in the future. [ABSTRACT FROM AUTHOR]

• A long enough C-rich DNA is constructed by TdT-mediated catalytic interaction. • The C-rich DNA occurs a configuration change to form cascade i-motifs. • A cascade i-motifs-dependent reversible EIS strategy is developed firstly. • The biosensor is well-suited for pH and TdT analysis. • The biosensor has excellent practicability in pH-adjusted complex matrix. In this study, we develop a novel and reversible electrochemical impedance strategy for pH and terminal deoxynucleotide transferase (TdT) analysis based on the TdT-assisted generation of long enough cytosine (C)-rich DNAs. The formation of this special DNA is rationally designed on 5′-thiol DNA modified Au electrode surface, and TdT can catalyze the extension of this 3′-OH end to form a long C-rich DNA in the presence of deoxycytidine triphosphate (dCTP). Here, we discover a reversible process, in which the TdT-generated C-rich DNA maintains an irregular single chain state under neutral conditions and some stable DNA i-motifs (cascade i-motifs) are formed due to the partial protonation of C under acidic conditions. More importantly, the electrochemical impedance spectroscopy (EIS) response varies with the configuration change of the TdT-mediated C-rich DNA under different pH conditions. In view of this, a unique EIS switch ("on-off-on") is constructed faithfully with the configuration change, thus achieving pH analysis well. Additionally, the TdT activity can be also detected well by recording the EIS response, because it can catalyze the DNA tailing process up to hundreds of cytosines; on the contrary, if its inhibitor exists, TdT-based extension and formation of cascade i-motifs will not occur. Using this strategy, the detection of limit for TdT is 0.79 × 10-5 U/mL (pH 7.0) and 0.25 × 10-5 U/mL (pH 5.8) (S/N = 3), respectively. All the above features make our biosensor a promising assay for in situ monitoring of pH and TdT in complex clinical diagnosis. [ABSTRACT FROM AUTHOR]

• In this work, a method for on-site visual detection of p -Aminophenol (p-AP) is reported. • The mechanism is that KIO 3 can be reduced by p-AP to generate I 2 to etch AuNRs. • The detection limit for p-AP is 0.27 μM with a dynamic range within 0.5 μM to 20 μM by the naked eye. • This colorimetric method is used to detect p-AP in environmental water, paracetamol tablets and human urine. p -Aminophenol (p-AP) is one of the common environmental pollutants with teratogenic effects, nephrotoxicity and genotoxicity. In this study, a novel colorimetric method for quickly, sensitive and on-site detection of p-AP was developed based on target induced etching of AuNRs, which will generate colorful color changes. Our investigation reveals that potassium iodate (KIO 3) can be reduced by p-AP to generate iodine (I 2), and I 2 can etch CTAB stabilized AuNRs along the longitudinal direction. As an emerging fascinating colorimetric material, LSPR extinction peak of AuNRs will shift to short wave direction with a color change from the initial tea red to brown, gray, dark green, cyan, blue, indigo, purple, purplish red and final pink. Under the optimal conditions, our strategy is analytically specific and sensitive for the detection of p-AP from 0.5 μM to 20 μM by the naked eye, and a detection limit of 0.27 μM was achieved. Meanwhile, this colorimetric method is used to detect p-AP in environmental water, paracetamol tablets and human urine. Hence, this proposed strategy has the advantages of rapid semi-quantitative analysis of p-AP with naked eyes, simple operation and good application prospect. [ABSTRACT FROM AUTHOR]

A new RNA aptamer-involved electrochemiluminescence (ECL) strategy for sensitive detection of histone acetyltransferase (HAT p300) is designed well based on coenzyme A (CoA)-initiated competitive response and advanced DNA nano-biotechnology. For the first time, this interesting analytical process is comprised of significant histone acetylation catalyzed by HAT p300, competitive replacement triggered by the specific binding of CoA and its RNA aptamer, stable scaffold guided by DNA nano-prism and typical amplification managed by hybrid chain reaction (HCR). Upon recognition of the RNA aptamer to CoA generated in acetylation, auxiliary DNA (A-DNA) which can be captured by three hanging arms of the fabricated DNA nano-prism immobilized onto Au electrode surface is released from the aptamer/A-DNA complex. Moreover, A-DNA can also open skillfully one hairpin DNA (H1), then turning into HCR process by alternating hybridization with the other hairpin DNA (H2). Abundant Ru(phen) 3 2+ molecules which have a strong interaction with dsDNA can result in a significant output. This proposed platform exhibits excellent specificity and sensitivity toward HAT p300 with a detection limit of 0.001 nM and takes on outstanding practicality and superiority, which presents a great potential for HAT p300 analysis in biomedical sciences. [ABSTRACT FROM AUTHOR]

In this study, coenzyme A (CoA)-based coordination polymers (CPs) have been generated in situ by exploiting the reaction of thiols with metal ion (Au(III) or Ag(I)), which are dependent on both thiol-metal and aurophilic metal∙metal interaction. It is interesting to note that CPs-related biosensing capabilities toward some biomolecules including ascorbic acid (AA), cysteine (Cys) and glutathione (GSH) are also investigated via SYBR Green II (SGII)-derived fluorescence switchable mechanisms. The synthesized CPs display especial RNA-like structure and are capable of initiating the fluorescence of SGII. Conversely, AA, Cys or GSH can give rise to the structural destruction of RNA-like CPs, thus inhibiting the fluorescence signal, and quantitative detection of these biomolecules are achieved favorably with a detection limit of 7.2, 0.55 and 0.48 nM, respectively. Meanwhile, the fascinating fluorescence on-off property and simple synthetic process are employed to build a series of basic logic gates (YES, NOT, OR, AND, INHIBIT and NOR) and multiple configurable logic gates (OR-AND and OR-OR-INHIBIT) along with different logic inputs. In view of these, developing CoA-based CPs as a new material to execute logic operations provides a valuable platform to establish the next generation of advanced molecular devices for clinic diagnostic and biomedical research. • CoA-based coordination polymers emit strong fluorescence after SGII insertion. • Novel CoA-metal coordination polymer-derived logic gates are first presented. • Some biomolecules are found to be capable of inhibiting the fluorescence. • The proposed biosensor can be applied for probing AA, Cys and GSH sensitively. • Some complicated and advanced logic gates are established by biomolecules. [ABSTRACT FROM AUTHOR]

Abnormal histone acetyltransferases (HAT) activity gives rise to all kinds of cellular diseases. Herein, we first report a coenzyme A (CoA)-aptamer-facilitated label-free electrochemical stripping biosensor for sensitive detection of HAT activity via square wave voltammetry (SWV) technique. The presence of HAT can lead to the transfer of the acetyl group from acetyl coenzyme A (Ac-CoA) to lysine residues of substrate peptide, thus generating CoA molecule. Later, CoA, which acts as an initiator, can embrace its aptamer via the typical target-aptamer interaction, then arousing deoxynucleotide terminal transferase (TdT)-induced silver nanoclusters (AgNCs) as signal output. Under optimized conditions, the resultant aptasensor shows obvious electrochemical stripping signal and is employed for HAT p300 analysis in a wide concentration range from 0.01 to 100 nM with a very low detection limit of 0.0028 nM (3δ/slope). The good analytical performances of the biosensor depend on the strong interaction of CoA and its aptamer and abundant stripping resource rooted from AgNCs. Next, the proposed biosensor is used for screening HAT's inhibitors and the practical HAT detection with satisfactory results. Therefore, the new, simple and sensitive HAT biosensor presents a promising direction for HAT-targeted drug discovery and epigenetic research. • A novel SWV stripping strategy for HAT p300 analysis is first presented. • Interaction of Coenzyme A and its aptamer first serves as an initiator. • TdT-induced silver nanoclusters act as electrochemical signal resources. • The biosensor is exploited for HAT p300 and its inhibitors detection. • The platform shows great potential applications in real biological sample. [ABSTRACT FROM AUTHOR]

A versatile protocol has been developed for highly sensitive magnetic relaxation detection of the analyte based on the fabrication of MnO nanoparticles (NPs) assemblies. Based on the strategy that positively charged analyte could induce the assembly of negatively charged MnO NPs through electrostatic interaction, which will generate the change of magnetic relaxation rate of MnO NPs, we achieved highly sensitive and convenient detection of the analytes. By applying the detection of melamine as an example, we found that the detection limit can be as low as 0.733 ppb. Furthermore, this strategy has been applied for the initially detection of commercially available milk spiked with melamine as proof of its potential applicability of detection in complicated food samples. Image 1 • The rational design of MnO nanoparticles assemblies enables the highly sensitive magnetic relaxation detection of analytes. • The detection limit of melamine via magnetic resonance imaging based on MnO nanoparticles can be as low as 0.733 ppb. • The assembly based magnetic resonance imaging strategy can be widely applicable to detect other analytes. [ABSTRACT FROM AUTHOR]