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Abstract: A solid-state electrochemiluminescence (ECL) biosensing switch incorporating quenching of ECL of ruthenium(II) tris-(bipyridine) (Ru(bpy)3 2+) by ferrocene (Fc) has been successfully developed for DNA hybridization detection. The important issue for this biosensing system is based on the ferrocene-labeled molecular beacon (Fc-MB), i.e. using the special Fc-MB to react with the target DNA and then change its structure, resulting in an ECL intensity change. Under the optimal conditions, the difference of ECL intensity before and after the hybridization reaction (ΔI ECL) was linearly related to the concentration of the complementary sequence in the range of 10fM–10pM and the detection limit was down to 1.0fM. [Copyright &y& Elsevier]

Abstract: Coiled carbon nanostructure (CNS) is prepared by a catalytic chemical vapor deposition (CVD) process on copper/chromium films deposited by radio frequency (RF) sputtering. Uniform CNS with coiled structure is fabricated by changing the size of the catalyst particles. The effects of Cu catalyst size and RF sputtering power, on the growth of the coiled CNS are discussed, and the results importantly conclude that Cu-catalyzed CVD offers a preferable control of coiled CNS to optimize the field emission property for application. [Copyright &y& Elsevier]

Since Waston and Crick established the double helical structure of DNA in 1953, nucleic acid research has become one of the most important fields in life science. Therefore, DNA biosensors based on DNA hybridization plays a more and more important role in DNA analysis. This review briefly introduces our group's research work in the electrochemical DNA biosensor field including DNA immobilization schemes and hybridization marking techniques. The representative immobilization techniques are adsorption on the surface, covalent attachment on a functional surface, embedding in a polymeric matrix, and the self‐assembled monolayer method. The formation of double‐stranded DNA upon hybridization is commonly detected in connection with the use of an appropriate electro‐active hybridization intercalator, or labeling DNA by a simple electro‐active molecule or a powerful nanoparticle. [ABSTRACT FROM AUTHOR]

Abstract: We have demonstrated that specific DNA sequences could be covalently immobilized onto acid-oxidized and plasma-activated carbon nanotubes. While various functional supramolecular structures could be prepared by self-assembling of the acid-oxidized carbon nanotubes attached with DNA chains of complementary sequences, the DNA-immobilized aligned carbon nanobues have been demonstrated to be significant for sensing complementary DNA and/or target DNA chains of specific sequences with a high sensitivity and selectivity. [Copyright &y& Elsevier]

It has been long recognized that surface properties are of paramount importance for a broad range of materials and a large variety of devices. The recent development of nanoscience and nanotechnology has opened up novel fundamental and applied frontiers in surface functionalization and characterization. At the nanometre scale, the high surface-to-volume ratio characteristic of most nanomaterials has been demonstrated to have a tremendous influence of many fundamental material properties and device performance. In this paper, we present some of the important issues on the surface functionalization and characterization of polymers and carbon nanotubes for certain biomedical and optoelectronic applications and summarize our recent research activities along this line. [ABSTRACT FROM AUTHOR]

Abstract The rapid and cost-effective detection of bacteria is of great importance to ensuring food safety, preventing food poisoning. Herein, we developed a sensitive detection of Escherichia coli (E. coli) using bacteria-specific aptamer in conjunction with microchip capillary electrophoresis-coupled laser-induced fluorescence (MCE-LIF). Based on the differences between charge to mass ratios of free aptamer and bacteria-aptamer complex, which influence their electrophoretic mobilities, the separation of free aptamers and complex peaks by MCE could be achieved. Under optimal conditions, the sensitive detection of E. coli was achieved with a detection limit of 3.7 × 102 CFU mL−1, at a fast response of 135 s and a short detection length of 2.3 cm. The spiked recovery experiment showed that E. coli could be recovered from spiked drinking water and milk samples with recovery rates of 94.7% and 92.8%, respectively. This work demonstrates that the established detection strategy can be a useful tool for the detection and/or monitoring of E. coli in food and environment. Graphical abstract The measurement principle of aptamer-based microchip capillary electrophoresis platform for the detection of bacteria. The detection of the bacteria-aptamer complex and free aptamer was confirmed by microchip capillary electrophoresis. The four reservoirs are shown as follows: Sample Reservoir (S); Sample Waste Reservoir (SW); Buffer Reservoir (B); Buffer Waste Reservoir (BW). Lower markers are displayed as LM, while upper markers are displayed as UM. fx1 Highlights • This paper described the analysis of E. coli based on specific aptamers binding with bacteria. • The detection of E. coli was achieved with a detection limit of 3.7×102 CFU mL-1. • This method was applied for the detection of E. coli in water and milk samples. [ABSTRACT FROM AUTHOR]

Presents the direct synthesis of mesostructured lamellar molybdenum disulfides using a molten neutral n-alkylamine as the solvent and template. Features of the crystal structures of metal disulfides; Introduction of inorganic or organic guest species into the layer galleries of molybdenum disulfide; Development of molecular self-assembly method for preparing intercalated molybdenum disulfide compounds.

Foodborne bacteria are some of the most important human pathogens and can cause many diseases. In this study, multiplex PCR amplification combined with microchip electrophoresis (MCE) was studied to simultaneously and sensitively detect Staphylococcus aureus , Proteus mirabilis , and Enterobacter sakazakii . In order to simultaneously and accurately detect the aim bacteria, three pairs of primers were specially designed for the multiplex PCR amplification of the target genes of three bacteria, which were the specific genes corresponding to these bacteria respectively. After the DNA fragments of three bacteria were simultaneously extracted, the multiplex PCR amplification was performed by adding the three pairs of specific primers in the mixed DNA fragments solution. The multiplex PCR products of the three food-borne pathogens were analyzed by MCE and the limits of detection of target DNA fragments were 1.2–2.2 ng μL −1 , (S/N = 3). The limits of detection of the aim bacteria were calculated as 53 CFU mL −1 for Enterobacter sakazakii , 32 CFU mL −1 for Proteus mirabilis , 28 CFU mL −1 for Staphylococcus aureus , respectively. Satisfactory results were obtained when this method was applied to detect the three foodborne bacteria in milk samples. The experimental results show that this method has the advantages of quickness, less sample consumption, high selectivity and high sensitivity. [ABSTRACT FROM AUTHOR]

A novel metallocyclodextrins polymer was synthesized as artificial polymeric receptor. The polymer showed excellent adsorption stability on the surface of glassy carbon electrode. More interestingly, the receptor could be prepared by using molecular imprinting technique conveniently and the resulting polymer template exhibited excellent selectivity. These attractive characteristics will be significant for constructing ultrasensitive ECL sensors. [ABSTRACT FROM AUTHOR]

Here we report on the preparation and characterization of new electrodes based on aligned carbon nanotubes (ACNTs) for hemoglobin (Hb) electrochemistry and electrocatalysis. The ACNTs are obtained by a thermal chemical vapor deposition method under normal pressure. Then the electrodes are elaborated by first sputtering a thin Au film (thickness of 200 nm) onto the top of the ACNTs, and then removing the Au layer/ACNTs from the quartz substrate with the aide of hydrofluoric acid (HF) treatment. Field emission scanning electron microscopy (FESEM) demonstrates that after nitric acid (HNO3) treatment, the nanotubes of the removed Au layer are totally tip-opened, purified and organized in a perfect vertically aligned architecture. The final ACNTs electrode is obtained by attaching the Au layer of ACNTs onto a glassy carbon electrode. Then the electrode was modified to act as a matrix for hemoglobin (Hb) immobilization and as an electrode for Hb electroanalysis by the assistance of Au nanoparticles (AuNPs) and SiO2 gel. Due to the individual specific effects of AuNPs, SiO2 gel and ACNTs, the resulting SiO2/Hb-AuNPs/ACNTs electrode showed good direct electrochemistry of Hb with an apparent MichaelisMenten constant of 0.44 mM. The electrode showed an excellent electrocatalytic activity towards H2O2, possessing a linear range from 40 µM to 4 mM and the detection limit was 22 µM based on a signal to noise ratio of 3. [ABSTRACT FROM AUTHOR]

Abstract: High yield preparation of silver nanowires (AgNWs) was prepared by polyol method. In this developed polyol process, uniform AgNWs have been successfully synthesized at higher yield by introducing CuCl2·2H2O, when ethylene glycol is used as the solvent and reductant while poly vinyl pyrrolidone (PVP) is used as the capper agent. Then Ag thin films were made by screen printing using silver nanowires and nanoparticles as semitransparent conduction electrodes. The test results indicated that the electrical resistivity could be as low as 0.091Ω/□, when the transparence rate can reach 45–46%, which shows great promise in the improvement of conductive antireflection coating. [Copyright &y& Elsevier]

Abstract: An enzyme-based solid-state electrochemiluminescence (ECL) sensing platform for sensitive detection of a single point mutation is developed successfully using p53 tumor suppressor gene as a model analyte. A composite of multiwalled carbon nanotubes and Ruthenium (II) tris-(bipyridine) (MWNTs–Ru(bpy)3 2+) was prepared and coated on an electrode surface, which was covered by polypyrrole (PPy) to immobilize ssDNA. Then, the ssDNA recognized the gold nanoparticle (AuNP)-labeled p53 tumor suppressor gene, and produced AuNP-dsDNA electrode with AuNP layer. The surface adsorbed the glucose-dehydrogenase (GDH) molecules for producing ECL signal. This system combined enzyme reaction with ECL detection, and it can recognize sequence-specific wild type p53 sequence (wtp53) and muted type p53 sequence (mtp53) with discrimination of up to 56.3%. The analytic results were sensitive and specific. It holds promise for the diagnosis and management of cancer. [Copyright &y& Elsevier]

Abstract: A solid-state electrochemiluminescence sensing platform based on ferrocene-labeled structure-switching signaling aptamer (Fc-aptamer) for highly sensitive detection of small molecules is developed successfully using adenosine as a model analyte. Such special sensing platform included two main parts, an electrochemiluminescence (ECL) substrate and an ECL intensity switch. The ECL substrate was made by modifying the complex of Au nanoparticle and Ruthenium (II) tris-(bipyridine) (Ru(bpy)3 2+–AuNPs) onto Au electrode. An anti-adenosine aptamer labeled by ferrocene acted as the ECL intensity switch. A short complementary ssDNA for the aptamer was applied to hybridizing with the aptamer, yielding a double-stranded complex of the aptamer and the ssDNA on the electrode surface. The introduction of adenosine triggered structure switching of the aptamer. As a result, the ssDNA was forced to dissociate from the sensing platform. Such structural change of the aptamer resulted in an obvious ECL intensity decrease due to the increased quenching effect of Fc to the ECL substrate. The analytic results were sensitive and specific. [Copyright &y& Elsevier]

Abstract: In the paper, a new kind of vitamin B12 (acquo-cobalamine) chemically modified electrode was fabricated and applied in capillary zone electrophoresis coupled with amperometric detection (CZE-AD) for simultaneous determination of six antioxidants in fruits and vegetables. The catalytic electrochemical properties of the chemically modified electrode could obviously enhance oxidation peak heights responses by about five times to glutathione, ascorbic acid, vanillic acid, chlorogenic acid, salicylic acid, and caffeic acid compared with common carbon disk electrode. Furthermore, the effects of working electrode potential, pH and concentration of running buffer, separation voltage and injection time on CZE-AD were investigated. Under the optimum conditions, the six analytes could be completely separated and detected in a borate–phosphate buffer (pH 8.4) within 15min. Their linear ranges were from 2.5×10−7 to 1.0×10−4 molL−1 and the detection limits were as low as 10−8 molL−1 magnitude (S/N =3). The proposed method has been successfully employed to monitor the six analytes in practical samples with recoveries in the range 96.0–106.0% and RSDs less than 5.0%. Above results demonstrate that capillary zone electrophoresis coupled with electrochemical detection using vitamin B12 modified electrode as detector is of convenient preparation, high sensitivity, good repeatability, and could be used in the rapid determination of practical samples. [Copyright &y& Elsevier]

Abstract: A versatile method for preparing nanoporous polypyrrole (PPy) film using electrogenerated nanobubbles as templates on highly oriented pyrolytic graphite (HOPG) is presented using in situ electrochemical atomic force microscopy (EC-AFM). [Copyright &y& Elsevier]

Abstract: A novel and sensitive electrochemical DNA biosensor based on electrochemically fabricated polyaniline nanowire and methylene blue for DNA hybridization detection is presented. Nanowires of conducting polymers were directly synthesized through a three-step electrochemical deposition procedure in an aniline-containing electrolyte solution, by using the glassy carbon electrode (GCE) as the working electrode. The morphology of the polyaniline films was examined using a field emission scanning electron microscope (SEM). The diameters of the nanowires range from 80 to 100nm. The polyaniline nanowires-coated electrode exhibited very good electrochemical conductivity. Oligonucleotides with phosphate groups at the 5′ end were covalently linked onto the amino groups of polyaniline nanowires on the electrode. The hybridization events were monitored with differential pulse voltammetry (DPV) measurement using methylene blue (MB) as an indicator. The approach described here can effectively discriminate complementary from non-complementary DNA sequence, with a detection limit of 1.0×10−12 moll−1 of complementary target, suggesting that the polyaniline nanowires hold great promises for sensitive electrochemical biosensor applications. [Copyright &y& Elsevier]

Abstract: Platinum nanoparticles were used in combination with multi-walled carbon nanotubes (MWCNTs) for fabricating sensitivity-enhanced electrochemical DNA biosensor. Multi-walled carbon nanotubes and platinum nanoparticles were dispersed in Nafion, which were used to fabricate the modification of the glassy carbon electrode (GCE) surface. Oligonucleotides with amino groups at the 5′ end were covalently linked onto carboxylic groups of MWCNTs on the electrode. The hybridization events were monitored by differential pulse voltammetry (DPV) measurement of the intercalated daunomycin. Due to the ability of carbon nanotubes to promote electron-transfer reactions, the high catalytic activities of platinum nanoparticles for chemical reactions, the sensitivity of presented electrochemical DNA biosensors was remarkably improved. The detection limit of the method for target DNA was 1.0×10−11 moll−1. [Copyright &y& Elsevier]

Here, an Au–Cu dual-electrode tip was designed to monitor the effect of Cu2+ on the membrane permeability of a single living cell in situ using scanning electrochemical microscopy. The probe approach curves (PACs) were obtained using potassium ferricyanide as a redox mediator. Meanwhile, according to the simulation, theoretical PACs could be acquired. Thus, the cell membrane permeability coefficient (Pm) values were obtained by overlapping the experimental PACs with the theoretical values. Cu2+ was directly generated by electrolyzing the Cu electrode of the dual-electrode tip to investigate its effect on the cell membrane permeability in situ. This work has potential value to improve the understanding of the mechanism of acute heavy metal damage on the cell membrane and will also help clarify the role of heavy metal ions in physiological or pathological processes. [ABSTRACT FROM AUTHOR]

A new and sensitive electrochemical DNA hybridization detection assay, using tris(2,2′-bipyridyl)cobalt(III) [Co(bpy)33+]-doped silica nanoparticles as the oligonucleotide (ODN) labeling tag, and based on voltammetric detection of Co(bpy)33+ inside silica nanoparticles, is described. Electro-active Co(bpy)33+ is not possible for directly linking with DNA, it is doped into the silica nanoparticles in the process of nanoparticles synthesis for DNA labeling with trimethoxysilylpropydiethylenetriamine (DETA) and glutaraldehyde as linking agents. The Co(bpy)33+ labeled DNA probe is used to hybridize with target DNA immobilized on the surface of glassy carbon electrode. Only the complementary sequence DNA (cDNA) could form a double-stranded DNA (dsDNA) with the DNA probe labeled with Co(bpy)33+ and give an obvious electrochemical response. A three-base mismatch sequence and non-complementary sequence had negligible response. Due to the large number of Co(bpy)33+ molecules inside silica nanoparticles linked to oligonucleotide DNA probe, the assay showed a high sensitivity. It allows the detection at levels as low as 2.0×10−10 mol l−1 of the target oligonucleotides. [Copyright &y& Elsevier]

An electrochemical detection method for analyzing sequence-specific DNA using gold nanoparticle DNA probes and subsequent signal amplification step by silver enhancement is described. The assay relies on the electrostatic adsorption of target oligonucleotides onto the sensing surface of the glassy carbon electrode (GCE) and its hybridization to the gold nanoparticle-labeled oligonucleotides DNA probe. After silver deposition onto gold nanoparticles, binding events between probe and target were monitored by the differential pulse voltammetry (DPV) signal of the large number of silver atoms anchored on the hybrids at the electrode surface. The signal intensity difference permits to distinguish between the match of two perfectly matched DNA strands and the near-perfect match where just one base pair was wrong. Coupled with this ‘nanoparticle-promoted’ reduction of silver signal amplification method, the sensitivity of this electrochemical DNA biosensor has been increased by approximately two orders of magnitude and a detection limit of 50 pM of complementary oligonucleotides was obtained. [Copyright &y& Elsevier]

The detection of Staphylococcus aureus specific gene in combination with the mecA gene is vitally important for accurate identification of methicillin-resistant Staphylococcus aureus (MRSA). A homogeneous electrochemical DNA sensor was fabricated for simultaneous detection of mecA and nuc gene in MRSA. Metal-organic framework (type UiO-66-NH2) was applied as nanocarrier. Two electroactive dyes, methylene blue (MB) and epirubicin (EP), were encapsulated in UiO-66-NH2, respectively, and were locked by the hybrid double-stranded DNA. Based on the target-response electroactive dye release strategy, once target DNA exists, it completely hybridizes with displacement DNA (DEP and DMB). So DEP and DMB is displaced from the MOF surface, causing the release of electroactive dyes. Co-Zn bimetallic zeolitic imidazolate framework-derived N-doped porous carbon serves for electrode modification to improve electrocatalytic performance and sensitivity. The differential pulse voltammetry peak currents of MB and EP were accurately detected at − 0.14 V and − 0.53 V versus the Ag/AgCl reference electrode, respectively. Under the optimal conditions, the detection limits of mecA gene and nuc gene were 3.7 fM and 1.6 fM, respectively. Combining the effective application of MOFs and the homogeneous detection strategy, the sensor exhibited satisfactory performance for MRSA identification in real samples. The recovery was 92.6–103%, and the relative standard deviation was less than 5%. Besides, MRSA and SA can also be distinguished. This sensor has great potential in practical applications. [ABSTRACT FROM AUTHOR]

An electrochemical sensor based on dual functional Cu2+-modified metal–organic framework nanoparticles (Cu2+-NMOFs) for sensitive detection of bacterial lipopolysaccharide (LPS) is reported. Cu2+-NMOFs were prepared and characterized by SEM, EDS, XRD, and XPS. In this LPS sensor, LPS firstly immobilized in gold nanoparticles/reduced graphene oxide by C18 alkane thiol chains, since the LPS can interact with the C18 alkyl chains by strong intermolecular interactions. Then the Cu2+-NMOFs were captured by the anionic groups of the carbohydrate portions of LPS molecules and played a vital role of recognition unit. More importantly, the Cu2+-NMOFs can catalyze dopamine oxidation to generate aminochrome, resulting in a strong electrochemical oxidation signal. The electrochemical sensor based on dual functional Cu2+-NMOFs was investigated by differential pulse voltammetry, and the stripping peak currents of dopamine oxidized to aminochrome were used to monitor the level of LPS. The developed method demonstrated a wide linear range from 0.0015 to 750 ng/mL with a limit of detection of 6.1 × 10−4 ng/mL. The fabricated sensor was applied to detect LPS in mouse blood serum and satisfactory results were achieved. Compared to other detection schemes by using the LPS-binding proteins, peptides, and aptamer, the proposed LPS determination based on the catalytic peroxidase-mimicking NMOFs has some advantages such as good reproducibility, low detection limit, and excellent specificity. [ABSTRACT FROM AUTHOR]

Extracellular pH can indicate the variation in organelle function and cell state. It is important to measure extracellular pH (pHe) with a controllable distance. In this work, a potentiometric SECM dual-microelectrode was developed to monitor the pHe of MCF-7 cells under electrical stimulation. The distance between the dual-microelectrode and the cells was determined first with a gold microelectrode by recording the approaching curve, and the pH was determined using an open-circuit potential (OCP) technique with a polyaniline-modified Pt microelectrode. The pH microelectrode showed a response slope of 53.0 ± 0.4 mV/pH and good reversibility from pH 4 to pH 8, fast response within 10 s, and a potential drift of 1.13% for 3 h, and thus was employed to monitor the pHe of stimulated cells. The value of pHe decreased with the decrease in the distance to cells, likely due to the release of H+. With an increase in the stimulation potential or time, the pHe value decreased, as the cell membrane became more permeable, which was verified by fluorescence staining of calcein-AM/PI (propidium iodide). Based on these results, this method can be widely applied for determining the species released by biosystems at a controllable position. [ABSTRACT FROM AUTHOR]

Simultaneous detection of various intracellular biomarkers is promising for early diagnosis and treatment of cancer. Herein, we develop a novel method for high specific and ultrasensitive detection of liver cancer cell‐involved mRNAs: TK1 and c‐myc based on the split primer ligation‐triggered 8‐17 DNAzyme assisted cascade rolling circle amplification. Only two targets exist simultaneously, can trigger the rolling circle amplification to improve the accuracy and sensitivity. Meanwhile, an electrochemical molecular beacon, based on the host‐guest recognition between ferrocene groups and cucurbit urils [7] (CB[7]/Fc‐MB), is used to cause a "turn‐off" electrochemical signal which is decreased by disrupting its hairpin structure. Under the optimal conditions, the detection limit of TK1 and c‐myc mRNA is as low as 0.06 nM. Moreover, this method can be used to detect the TK1 and c‐myc mRNA in HepG2 cells and distinguish between cancer cells and their normal cells, proving that the method has the potential to detect the variation of biomarkers in vivo. [ABSTRACT FROM AUTHOR]

Potentiometric aptasensors enhanced by integrating advanced nanomaterials are of particular interest for the detection of multiplex species (e.g., proteins, bacteria, micro-organisms) due to their low cost, ease of operation, and low detection limits. However, potentiometric detection of small ionic species aptasensors is still challenging. This article describes the first example of a label-free G-quadruplex-based potentiometric aptasensing platform for the detection of Pb2+. Polyion oligonucleotide-labeled gold nanoparticles (AuNPs-DNA) as probes are modified on Au electrode, providing high-density negative charge on the electrode surface. These signal-amplifying probes can selectively form G-quadruplexes with the presence of Pb2+ ions and reduce the negative charges on the electrode surface, hence achieving potentiometric detection of Pb2+ ions with high selectivity. The AuNPs-DNA-based aptasensor shows an acceptable sensitivity over a wide range from 10−11 to 10−6 M with a detection limit of 8.5 pM. Furthermore, confirmed by coupled plasma mass spectrometry, the sensing platform is capable of performing effective and accurate detection of Pb2+ level in real water samples. The presented aptasensor offers a fast, convenient, low-maintenance, and highly sensitive alternative for on-site water pollution detections. Image 1 • A stable and selective potentiometric aptasensor for the detection of lead ions. • Applying a potentiometric method together with gold dendritic to detect small ions species. • Low-cost and low-power consumption design for label-free potentiometric aptasensor. [ABSTRACT FROM AUTHOR]

Herein we show that by appending bulky β‐cyclodextrin (CD) groups onto sheet‐forming peptoids, we obtain cylindrical micelles that further assembly into membranes and intertwined ribbons on substrates in aqueous solution, depending on the choice of solution and substrate conditions. In situ atomic force microscopy (AFM) shows that micelle assembly occurs in two steps, starting with "precursor" particles that transform into worm‐like micelles, which extend and coalesce to form the higher order structures with a rate and a degree of cooperativity dependent on pH and Ca2+ concentration. After co‐assembly with hydrophobic 4‐(2‐hydroxyethylamino)‐7‐nitro‐2,1,3‐benzoxadiazole (NBD) donors that occupy the hydrophobic core, followed by exposure to hydrophilic Rhodamine B as acceptors that insert into cyclodextrin, the micelles exhibit highly efficient Förster resonance energy transfer efficiency in aqueous solution, thereby mimicking natural light harvesting systems. [ABSTRACT FROM AUTHOR]

Herein we show that by appending bulky β‐cyclodextrin (CD) groups onto sheet‐forming peptoids, we obtain cylindrical micelles that further assembly into membranes and intertwined ribbons on substrates in aqueous solution, depending on the choice of solution and substrate conditions. In situ atomic force microscopy (AFM) shows that micelle assembly occurs in two steps, starting with "precursor" particles that transform into worm‐like micelles, which extend and coalesce to form the higher order structures with a rate and a degree of cooperativity dependent on pH and Ca2+ concentration. After co‐assembly with hydrophobic 4‐(2‐hydroxyethylamino)‐7‐nitro‐2,1,3‐benzoxadiazole (NBD) donors that occupy the hydrophobic core, followed by exposure to hydrophilic Rhodamine B as acceptors that insert into cyclodextrin, the micelles exhibit highly efficient Förster resonance energy transfer efficiency in aqueous solution, thereby mimicking natural light harvesting systems. [ABSTRACT FROM AUTHOR]

• A PEDOT-modified ultramicroelectrode was fabricated so that both signal amplification and tip locating were realized in one single tip. • A dual-signal-amplification DNA biosensing platform was established using PEDOT-modified tip in scanning electrochemical microscopy. • A good linear correlation between the signal current and concentration of target DNA (1 fM–100 fM) was achieved. • The detection limit of this method could reach 0.076 fM. • This method displays great potential in high-throughput bioanalysis with high sensitivity. A PEDOT-modified Pt microelectrode was used in SECM for DNA biosensing and combined with long self-assembled DNA concatemers to realize dual signal amplification. The approach curve could also be plotted for tip location using this modified microelectrode with no impact on the catalytic effect so that both signal amplification and tip locating were achieved in one single tip. The detection limit of this method reached 0.076 fM, providing an ultra-sensitive DNA biosensing platform. Furthermore, this strategy could be applied in scanning a DNA chip, showing great potential in high-throughput bioanalysis with high sensitivity. [ABSTRACT FROM AUTHOR]

Abstract In this study, a novel all-solid-state ion selective electrode (ASS-ISE) was developed for the detection of Cu2+ by open circuit potential (OCP) based on phytic acid (PA)@Ag, which forms a thin anion layer interacting with positive charged Cu2+. Due to the excellent conductivity and complexing ability with multi-chelating features, PA can selectively recognize metal ions and execute ion-electron conduction. Moreover, with the assistance of Ag nanoparticles, multiple PA molecules were connected, forming a network structure with the improved conductivity and stability. After optimizing the thickness of PA@Ag film, this ASS-ISE gave a near Nernstian behavior (31.3 ± 1.8 mV/dec) towards the variation of Cu2+ concentration in the range of 1.0 × 10−5 to 1.0 × 10−3 mol/L with a detection limit of 2.7 × 10−6 mol/L, and presented excellent selectivity and stability. Furthermore, it was applied in the analysis of Cu2+ in environmental waters with the satisfactory recoveries, and the results were consistent well with those obtained by inductively coupled plasma atomic emission spectrometer, providing a promising alternative for the on-site detection of Cu2+ with simplicity and reliability. [ABSTRACT FROM AUTHOR]

Abstract Cigarette smoke contains abundant toxicants, and profiling its cytotoxicity represents a critical topic. In this study, cell-substrate impedance sensing (ECIS) was used to measure the cytotoxicity of 4‑(methylnitrosoamino)‑1‑(3‑pyridinyl)‑1‑butanone (NNK), nicotine, and the total particle material (TPM) of high-tar and low-tar cigarettes on CHO-K1 cells. Normalized impedance values at 3174 Hz were collected with microscopic imaging as an assistant, showing the dynamics of cell damage and the ability for cell self-recovery. The NI determination of the four toxicants indicated that, as the concentration of toxicants increased, cigarette smoke produced more intense toxic effects on the cells, and the ability of cell self-recovery worsened until there was permanent damage to the cells and the cells eventually died. Furthermore, the survival rate of the cells was obtained during treatment. NRU assays as a comparison were developed for evaluating the cytotoxicity by calculating the IC 50. Both methods showed that the cytotoxicity decreased in the following order: the TPM of high-tar cigarettes, TPM of low-tar cigarettes, nicotine and NNK. The sensitivity of the ECIS method was higher. Our work provides a useful and convenient approach for determining the cytotoxicity of cigarettes in a real-time, label-free manner, contributing to the development of low-toxicity cigarettes. Graphical abstract Unlabelled Image Highlights • ECIS was employed to assess the cytotoxicity of four toxicants on CHO-K1 cells. • ECIS was used to assess cell self-recovery after poisoning. • Cell viability rates and IC 50 values were obtained by NI values and NRU assays. [ABSTRACT FROM AUTHOR]

Abstract Herein, a novel and convenient electrochemically active–inactive switching molecular beacon based on hemin (Hs-MB) has been designed for easy discrimination of single nucleotide polymorphisms (SNPs) and sensitive detection of insulin. The electrochemically active changing capability of Hs-MB is based on two identical hemin groups labeled at both ends of MB sequence in dimer or monomer forms depending on the conformation of MB which is in stem-loop structure or line shaped structure. The Hs-MB assay permits discrimination of SNPs and the highly sensitive and specific detection of insulin with detection limit successively as low as 0.5 pmol/L. Even at a very low target concentration, the Hs-MB assay also shows a good specificity in the presence of other potentially interfering components. The experimental results also show that Hs-MB can also be used for the accurate and rapid monitoring of insulin secretion by glucose-stimulated from MIN6 cells at different time periods, demonstrating that Hs-MB has potential in monitoring of biomarker variation in vivo. Graphical abstract Schematic illustration of the sensing principle for insulin detection by Hs-MB. fx1 Highlights • The Hs-MB assay possesses high electrochemical activity and good thermal stability. • It can directly discriminate the SNPs and sensitively detects insulin. • It can monitor the insulin secretion from mouse pancreatic β-cells at different time periods. [ABSTRACT FROM AUTHOR]

• SECM combined with a transwell co-culture device has been proposed. • Various in-situ SECM detection modes have been exploited. • Intercellular signal transduction was in-situ investigated under UVB irradiation. • Extracellular ROS and pH, membrane permeability and cell height were monitored. • H + is one of signaling molecules in signal transduction between skin cells. Skin is the first barrier of the immune system, protecting the body from various damages of the external environment, the signal transduction between skin cells plays an important role in skin healing and injury. Scanning electrochemical microscopy (SECM) combined with a Transwell co-culture device has been proposed to in-situ investigate the signal transduction between skin cells with UVB irradiation, in which, keratinocyte HaCaT cells and fibroblast HFF cells were used as signaling cells and signal-receiving cells, respectively. Extracellular ROS and pH, cell membrane permeability and cell height were in-situ monitored by multi-potential step waveform in SECM (SECM-MPSW), potentiometric mode, shear force mode and the probe approach curve (PAC) combined with COMSOL simulation, respectively. The results revealed that UVB irradiation stimulated HaCaT cells to release excess H +, which diffused to HFF cells and increased the ROS release and membrane permeability with unchanged cell height. Therefore, this work provides an effective way to in-situ investigate intercellular signal transduction. [ABSTRACT FROM AUTHOR]

In this study, distinguishing skin cancer cells (A431) and normal cells (HaCaT) was achieved using electrical impedance spectroscopy (EIS) with a novel developed device. The proliferation behaviors of the two cell types during a culture period of 5 days were characterized by the normalized impedance measured at 1465 Hz with simultaneous microscopic imaging for assistance. By fitting to the established equivalent circuits, A431 cells generated smaller resistance ( R c ) values with smaller increasing variation, and comparable capacitance ( C c ) values with similar decreasing variation compared with HaCaT cells. Moreover, C c values were linearly correlated to the cell number. The results indicate that these two cell types can be distinguished with EIS based on the differences in the values and variation trends of R c and C c during the proliferation process in a real-time and label-free manner. Our work supplies a useful analytical approach for skin cancer cell research and may facilitate the early diagnosis of skin cancer. [ABSTRACT FROM AUTHOR]

A novel electrochemical DNA (E-DNA) biosensing strategy was designed and used for the detection of breast cancer susceptibility gene (BRCA-1). The biosensor was based on gold nanoparticles-reduced graphene oxide (AuNPs-GO) modified glass carbon electrode (GCE) covered with the layer of molecularly imprinted polymers (MIPs) synthesized with rhodamine B (RhB) as template, methacrylic acid (MAA) as the monomer, and Nafion as additive. The signal amplification tracing tag SiO 2 @Ag NPs were prepared by covering AgNPs on the surface of SiO 2 nanoparticles in situ, and then DNA probes were modified on AgNPs by Ag-S bond, forming the composites SiO 2 @Ag/DNA. In presence of target DNA (T-DNA), homogeneous hybridization was performed with SiO 2 @Ag/DNA and RhB labeled DNA, and the resulting SiO 2 @Ag/dsDNA/RhB was specifically recognized by MIPs via the interaction between imprinting cavities and RhB. Under optimal conditions, the proposed biosensor exhibited wide linear range from 10 fM to 100 nM, low detection limit of 2.53 fM (S/N = 3), excellent selectivity, reproducibility, stability, and feasibility in serum analysis. Overall, these findings suggest the promising prospects of the proposed biosensing strategy in clinical diagnostics. [ABSTRACT FROM AUTHOR]

A rapid and sensitive PCR based strategy in combination with microchip capillary electrophoresis (MCE) was employed to simultaneously detect three foodborne pathogenic bacteria. Three pairs of primers were specially designed for the amplification of target genes from Escherichia coli ( E. coli ), Staphylococcus aureus ( S. aureus ) and Salmonella enterica serovar Typhimurium ( S. Typhimurium). The PCR products along with standard DNA fragments were employed to optimize the separation conditions in MCE. Under optimal conditions, detectable separation of the PCR products (1.6–3.5 ng μL −1 ) from the three foodborne pathogenic bacteria was achieved within 135 s. The limits of detection of the three bacteria were concluded to be as low as 45 CFU mL −1 for E. coli , 62 CFU mL −1 for S. aureus and 42 CFU mL −1 for S. Typhimurium. The RSD of migration time was in the range of 0.5–0.8%. We conclude that MCE along with PCR holds real potential for rapid analysis and detection of nucleic acids from routine foodborne pathogenic bacteria. [ABSTRACT FROM AUTHOR]

In this study, a novel and sensitive electrochemical aptasensing platform was fabricated for the detection of the breast cancer biomarker HER2. HER2 aptamer was firstly hybridized with ferrocene-labeled DNA/Au nanospheres (FcNS), and then bound with the target HER2. The released FcNS homogeneously hybridized with horseradish peroxidase-labeled DNA/Au nanospheres (HRPNS). Benefiting from the introduction of RecJ f exonuclease, HER2 was recycled as the degradation of aptamer and bound another aptamer connected on FcNS. Thus, FcNS/HRPNS in large amounts was generated and captured by the modified Au electrode through the host-guest recognition between beta-cyclodextrin (β-CD) and ferrocene (Fc). Horseradish peroxidase (HRP) catalyzed o-PD in presence of H 2 O 2 , producing a significantly amplified signal. Under the optimal conditions, the fabricated aptasensing platform showed an excellent sensitivity with a low detection limit of 4.9 ng ml −1 (S/N = 3), and high specificity towards HER2. Furthermore, this proposed strategy presented the good reliability and applicability in the analysis of human serum samples, showing great potential for applications in early diagnosis of breast cancer. [ABSTRACT FROM AUTHOR]

Cancer became a global public health problem and one of the most causes of death, and early diagnosis will decrease mortality and extend lifespan of patients. In this study, the simultaneous detection of four tumor markers in lung cancer (alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), cytokeratin-19-fragment (Cyfra21-1)) was achieved for the first time using immune sandwich structures coupled with generation collection (GC) mode of scanning electrochemical microscopy (SECM). The proposed method exhibited excellent performance in quantitative detection of the four target proteins. A good linear correlation between the signal current issued from reduction of p-benzoquinone (BQ) oxidized from hydroquinone (H 2 Q) and the amount of target tumor markers at logarithmic protein concentrations ranging from 5 ng/mL to 1 μg/mL was achieved. The detection limit was also low, meeting the needs of clinical use. The specificity was satisfactory and signal current of the target protein was unaffected by other simultaneously detected target proteins and common interfering species. Overall, the proposed method looks promising for high-throughput protein determination based on SECM, which could potentially be applied in clinical lung cancer diagnosis. [ABSTRACT FROM AUTHOR]

The detection of Salmonella enterica serovar Typhimurium ( S. Typhimurium ) is very important for the prevention of food poisoning and other infectious diseases. Here we reported a simple and sensitive strategy to test S. Typhimurium by microchip capillary electrophoresis couple with laser-induced fluorescence (MCE-LIF) based on the specific reaction between the bacterium and corresponding aptamers. Based on the differences in charge to mass ratio between bacteria-aptamer complexes and free aptamers, a separation of the complexes and free aptamers could be obtained by MCE. The optimal parameters of the specific reaction including fluorescent dye concentration, Mg 2+ concentration, incubation time, and pH of incubation solution were carefully investigated. Meanwhile, a non-specific DNA was exploited as a contrast for the detection of S. Typhimurium. Under the optimal conditions, a rapid separation of the bacteria-aptamer complex and free aptamers was achieved within 135 s with a limit of detection (S/N = 3) of 3.37 × 10 2  CFU mL −1 . This method was applied for the detection of S. Typhimurium in fresh milk samples and a recovery rate of 95.8% was obtained. The experimental results indicated that the specific aptamers are of enough biostability and the established method could be used to analyze S. Typhimurium in foods. [ABSTRACT FROM AUTHOR]

A new method of capillary electrophoresis (CE) using laser induced fluorescence (LIF) detection via online pre-concentration techniques including transient trapping combined with the dynamic pH junction mode was developed for the sensitive determination of glutathione in biological samples. The mechanism together with the important parameters governing the pre-concentration and separation were investigated in order to obtain maximum resolution and sensitivity. The analytes were compressed into a narrow zone due to the effect of the dynamic pH junction mode, and then transiently trapped by SDS micelles at the interface of the sample and micellar areas. Under the optimal conditions, the limits of detection for reduced glutathione, glycine, oxidized glutathione, cysteine, and glutamic acid were 0.01, 0.01, 0.5, 0.7, and 0.1 nM (S/N = 3), respectively. The enhancement factors obtained when using the transient trapping combined with the dynamic pH junction mode as a pre-concentration process were enhanced from 87 to 430 when compared to the results obtained by the classical capillary zone electrophoresis (CZE) mode. Moreover, this optimized method was successfully applied to bacteria (Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus) and HaCaT cell samples for the determination of reduced glutathione with satisfactory recoveries. [ABSTRACT FROM AUTHOR]

Skin wound healing represents a critical medical topic. For its ideal case, the injured tissue can repair quickly without scars. In this paper, an ECIS device was developed using nano-grooves to simulate internal extracellular matrix (ECM) with 75 nm in depth and 200 nm in width of grooves and ridges. HFF and HaCaT cells were cultured but only HFF cells could orient along the nano-grooves. In the cell migration and proliferation occurred during the wound healing, HFF and HaCaT cells both presented increased normalized impedance (NI) values at the characteristic frequencies of 977 Hz and 1465 Hz, respectively. Compared to flat electrodes, nano-grooves electrodes generated less intense impedance signals in HFF cell migration and proliferation, and HaCaT cell migration, but more intense ones in HaCaT cell proliferation. Cell images were captured simultaneously and the statistical analysis demonstrated that the nano-grooves electrode could accelerate the migration while slow down the proliferation. After establishing the correlations between impedance response and cell behaviors, it could be found that the NI values increased all linearly the rising of recovery degree and cell number. Under the equal changes of recovery degree and cell number on nano-grooves, HFF cells produced the both declined impedance signals, because of the elongation, while, HaCaT cells created the same and deduced NI variation rates, due to the unchanged morphology and aggregation growth, respectively. Our work provides a useful approach for the clinical monitoring of skin wound healing in a real-time and label-free manner, potentially promoting the development of regenerative medicine. [ABSTRACT FROM AUTHOR]

Due to their unique physical and chemical properties, 2D materials have attracted intense interest for applications in filtration, sensing, nanoelectronics, and biomedical devices. Peptoids are a class of biomimetic sequence-defined polymers for which certain amphiphillic sequences self-assemble into 2D crystalline materials with properties that mimic those of cell membranes. In this study the ability of these membrane-like materials to self-repair following damage on a range of substrates is explored. In situ atomic force microscopy (AFM) is used to both create damage and image the subsequent repair process. Damage is induced by using the AFM to scribe peptoid-free patterns within a preassembled membrane. The results show here that, upon introduction of a peptoid-containing solution, for a suitable range of pH conditions, the damage is eliminated through assembly of the peptoids at the newly created edges, regardless of whether the substrates are negatively or positively charged and even in the absence of an underlying surface. The rate of the advancing edge depends on the edge orientation, the pH, and the composition of the substrate. Moreover, if the solution contains a second peptoid having an identical sequence in the hydrophobic block, repair of the defects results in nanoscale patterns of the new peptoid, even if the hydrophilic regions are distinct. Consequently, this ability to self-repair can be exploited to create nm-sized patterns of distinct functional groups within a single coherent membrane. [ABSTRACT FROM AUTHOR]

Recently, many strategies have been developed to trace the breast cancer susceptibility gene (BRCA), which is closely related to the occurrence of breast cancer. In this work, a novel recyclable electrochemical sensing platform was constructed to detect BRCA DNA based on the homogeneous hybridization of this target sequence with ferrocene-labeled DNA/Au nanospheres (FcNS) and horseradish peroxidase-labeled DNA/Au nanospheres (HRPNS) concatamers, and the host-guest interaction between cucurbit [7]uril (CB [7]) adsorbed on the electrode and Fc on the hybridization complex. With the optimization of experimental conditions, the fabricated sensing platform showed improved sensitivity with a low detection limit of 25 pM (S/N = 3), contributed by the dual amplification of signal using FcNS and HRPNS concatamers, and high specificity for BRCA DNA. The captured complex was dissociated from CB [7]-modified electrode with the rise of pH value to recycle the sensing platform. Furthermore, this detection strategy displayed the reliability and applicability in the analysis of human serum samples, indicating great potential for applications in early diagnosis of breast cancer. [ABSTRACT FROM AUTHOR]

A capillary column was prepared by continuously packing ostadecylsilane (ODS) and taurine derivatized silica (TDS) in one column without interface. This continuously packing chromatography (CPC) column is easy to operate, has good stability and shows simultaneously separation of both polar and non-polar compounds. The simultaneous separation of a series of complex samples with highly hydrophobic components (benzene, toluene, ethylbenzene, and PAHs) and highly hydrophilic components (biogenic amines, bases and nucleosides) using this CPC method was investigated. The relative parameters such as the volume fraction of acetonitrile and length of the ODS and the TDS phases were investigated and optimized. The experimental results show that this column combines the advantages of both ODS and TDS stationary phases, and exhibits a reversed phase liquid chromatography (RPLC) mode followed by a hydrophilic interaction liquid chromatography (HILIC) mode when 80% of acetonitrile was used in the mobile phase. The satisfactory results indicate that the CPC method provides an easy way to simultaneously separate polar and non-polar compounds. [ABSTRACT FROM AUTHOR]

All-solid-state potentiometric sensors that are easily miniaturized and arrayed are widely used in home diagnostics. However, changes in sample matrix compositions tend to affect the basic potential of the potentiometric sensor, and pH of sample could change the response slope, thus affecting the detection reliability. This study takes the detection of glucose in urine as a model to increase the reliability of potentiometric sensors in home detection. PtAu/CNTs nanozyme modified by diboronic acid has been designed, showing better catalytic selectivity for glucose by experiments and theoretical calculations. Moreover, glucose electrode group in a multi-calibration glucose potentiometric sensing array can realize the basic potential calibration of sensing channel by the calibration channel. Meanwhile, the pH electrode group can not only measure the urine pH, but also calibrate the response slope of the glucose electrode group, thus improving the reliability of home detection. [Display omitted] • A multi-calibrated glucose potentiometric (MCGP) sensing array was designed. • The MCGP sensing array can calibrate the basic potential and response slope. • The MCGP sensing array can improve the reliability of home detection. • Diboronic acid-PtAu/CNTs (SDBA-PtAu/CNTs) nanozyme was designed. • SDBA-PtAu/CNTs showed better catalytic selectivity for glucose. [ABSTRACT FROM AUTHOR]

In this paper, a microchip electrophoresis method based on on-line multiple-preconcentration techniques combining field-amplified sample stacking and reversed-field stacking was developed for highly efficient analysis of acrylamide in food products. The related mechanism as well as important parameters governing separation and preconcentration have been investigated in order to obtain maximum resolution and sensitivity. The best separation was achieved using a 100 mM borate solution at pH 9.3 as running buffer, and a sensitivity enhancement factor of 432 was obtained using this concentration method under optimal conditions. The detection limit of acrylamide was 1 ng/mL, which was comparable to those previously obtained using CE methods with on-line preconcentration techniques and was 41–700 times lower than those previously reported CE methods without concentration process. The proposed method also gave satisfactory and reliable results in the analysis of acrylamide in potato chips and French fries. [ABSTRACT FROM AUTHOR]

Microchip electrophoresis (MCE) is particularly attractive as it provides high sensitivity and selectivity, short analysis time and low sample consumption. An on-line preconcentration strategy combining field-amplified stacking (FASS) and reversed-field stacking (RFS) was developed for efficient and sensitive analysis of neurotransmitters in real urine samples by MCE with laser induced fluorescence (LIF) detection. In this study, the multiple-preconcentration strategy greatly improves the sensitivity enhancement and surpass other conventional analytical methods for neurotransmitters detection. Under optimal conditions, the separation of three neurotransmitters (dopamine, norepinephrine and serotonin), was achieved within 3 min with limits of detection (S/N = 3) of 1.69, 2.35, and 2.73 nM, respectively. The detection sensitivities were improved by 201-, 182-, and 292-fold enhancement, for the three neurotransmitters respectively. Other evaluation parameters such as linear correlation coefficients were considered as satisfactory. A real urine sample was analyzed with recoveries of 101.8–106.4%. The proposed FASS-RFS-MCE method was characterized in terms of precision, linearity, accuracy and successfully applied for rapid and sensitive determination of three neurotransmitters in human urine. [ABSTRACT FROM AUTHOR]

In this work, a recyclable electrochemical sensing platform to detect breast cancer susceptibility gene (BRCA) was constructed by pillararenes based host–guest recognition and homogeneous DNA hybridization. BRCA target DNA (T-DNA) formed sandwich-type DNA via homogeneous hybridization with methylene blue labeled signal DNA and alkylamino modified capture DNA, which could form complexes with pillararenes. Such sandwich-type DNA was captured by a novel trithiocarbonate modified pillar[5]arene (P5A-CTA) which was immobilized on the Au electrode. With the help of enzyme amplification, the electrochemical detection signal of target DNA in sensing platform was apparently amplified. This sensing platform exhibited wide linear range and excellent specificity, and was particularly recyclable after simple washing with hot acetonitrile due to the reversible host–guest complexation between P5A-CTA and alkylamino modified DNA. [ABSTRACT FROM AUTHOR]

The long DNA concatemers have been well developed to fabricate various biosensing platforms for the signal amplification. Herein, this signal amplification strategy was firstly used for an ultrasensitive scanning electrochemical microscopy (SECM)-based DNA biosensing platform. This platform was constructed through the hybridization of target DNA (TD) with thiol-tethered DNA capture probes (CP), immobilized on the gold substrate surface, and biotinylated DNA signal probes (SP), which formed then the long DNA concatemers through the continuous self-assembly with alternating DNA auxiliary probes (AP). The streptavidin-horseradish peroxidase (HRP) was linked to the long DNA concatemers through biotin-streptavidin interaction. In the HRP-catalyzed reaction, hydroquinone (H 2 Q) was oxidized to benzoquinone (BQ) with H 2 O 2 at the modified substrate surface where sequence-specific hybridization had occurred, and the BQ generated could be monitored by a SECM tip. This platform exhibited a low detection limit of 0.18 aM estimated by the 3σ rule. Combined with DNA microarrays, four kinds of TDs (100 fM) as the models were detected simultaneously by using this proposed strategy, which also demonstrated sufficient selectivity to distinguish specific DNA sequences and good reproducibility. This method opens a promising direction to improve the SECM sensitivity for high-throughput DNA detection. [ABSTRACT FROM AUTHOR]

A novel Congo red (CR) derivatized silica stationary phase was prepared and packed into a fused silica capillary tube for nano-flow HPLC. A variety of analytes including poly-aromatic hydrocarbons, parabens, acids, sulfonamides, bases, and nucleosides were successfully separated using the CR. In comparison with commercial ODS columns, this new stationary phase has a different separation mechanism (hydrophobically-assisted ion-exchange), which was evident in the separation of benzoic acid derivatives and sulfonamides. The successful application of CR-bonded silica stationary phase in the HILIC and PALC modes demonstrates the effectiveness of this potential chromatographic material in nano flow HPLC. [ABSTRACT FROM AUTHOR]

A novel Congo red (CR) derivatized silica stationary phase was prepared and packed into a fused silica capillary tube for nano-flow HPLC. A variety of analytes including poly-aromatic hydrocarbons, parabens, acids, sulfonamides, bases, and nucleosides were successfully separated using the CR. In comparison with commercial ODS columns, this new stationary phase has a different separation mechanism (hydrophobically-assisted ion-exchange), which was evident in the separation of benzoic acid derivatives and sulfonamides. The successful application of CR-bonded silica stationary phase in the HILIC and PALC modes demonstrates the effectiveness of this potential chromatographic material in nano flow HPLC. [ABSTRACT FROM AUTHOR]