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Background and Aims: Accurate biomarkers to predict outcomes following discontinuation of nucleos(t)ide analogue (NA) therapy are needed. We evaluated serum hepatitis B core‐related antigen (HBcrAg) level as a biomarker for predicting outcomes after NA discontinuation. Methods: Patients with HBeAg‐negative chronic hepatitis B (CHB) without cirrhosis were enrolled in a prospective trial evaluating clinical outcomes until 96 weeks after NA discontinuation. End of treatment (EOT) and off‐treatment levels of serum HBcrAg, HBsAg, HBV RNA and HBV DNA were used to predict key clinical outcomes including hepatitis flare (ALT ≥5 × ULN and HBV DNA > 2000 IU/mL). The SCALE‐B score was calculated for the purposes of model validation. Results: HBcrAg was tested amongst 65 participants. The median age was 54 years, 54% were male and 83% were Asian. HBcrAg was detectable in 86% patients. HBcrAg level ≥4 log U/mL at EOT was predictive of hepatitis flare [8/10 (80%) vs. 17/55 (31%), p =.001]. The presence of either HBcrAg ≥4 log U/mL or detectable HBV RNA at EOT predicted for both biochemical relapse and hepatitis flare. The SCALE‐B model at EOT predicted for virological relapse, biochemical relapse, hepatitis flare and HBsAg loss in this cohort. An increase in the serum HBcrAg level off‐treatment was also associated with hepatitis flare. No participant with EOT HBcrAg level ≥4 log U/mL achieved HBsAg loss. Conclusions: High levels of serum HBcrAg predict for hepatitis flare after stopping NA therapy and low likelihood of HBsAg loss at week 96. People with high levels of serum HBcrAg are not suitable candidates for NA discontinuation. [ABSTRACT FROM AUTHOR]

Urinary cell-free DNA (ucfDNA) is a potential biomarker for bladder cancer detection. However, the biological characteristics of ucfDNA are not well understood. We explored the roles of deoxyribonuclease 1 (DNASE1) and deoxyribonuclease 1-like 3 (DNASE1L3) in the fragmentation of ucfDNA using mouse models. The deletion of Dnase1 in mice (Dnase1-/-) caused aberrations in ucfDNA fragmentation, including a 24-fold increase in DNA concentration, and a 3-fold enrichment of long DNA molecules, with a relative decrease of fragments with thymine ends and reduction of jaggedness (i.e., the presence of single-stranded protruding ends). In contrast, such changes were not observed in mice with Dnase1l3 deletion (Dnase1l3-/-). These results suggested that DNASE1 was an important nuclease contributing to the ucfDNA fragmentation. Western blot analysis revealed that the concentration of DNASE1 protein was higher in urine than DNASE1L3. The native-polyacrylamide gel electrophoresis zymogram showed that DNASE1 activity in urine was higher than that in plasma. Furthermore, the proportion of ucfDNA fragment ends within DNase I hypersensitive sites (DHSs) was significantly increased in Dnase1-deficient mice. In humans, patients with bladder cancer had lower proportions of ucfDNA fragment ends within the DHSs when compared with participants without bladder cancer. The area under the curve (AUC) for differentiating patients with and without bladder cancer was 0.83, suggesting the analysis of ucfDNA fragmentation in the DHSs may have potential for bladder cancer detection. This work revealed the intrinsic links between the nucleases in urine and ucfDNA fragmentomics. Author summary: Cell-free DNA (cfDNA) in various bodily fluids, for example blood plasma and urine, is of great importance for noninvasive cancer detection and noninvasive prenatal testing. Many emerging studies on the fragmentation of plasma DNA (i.e., fragmentomics) have received much recent interest. However, the fragmentomics in urinary cfDNA (ucfDNA) remained much less explored. In this study, we explored the biological links between ucfDNA fragmentation and DNA nucleases, using mice for which either the Dnase1 or Dnase1l3 gene was genetically inactivated. Interestingly, we found that the deletion of Dnase1, but not Dnase1l3, caused dramatic alterations of ucfDNA fragmentation patterns, including the elevation of DNA concentration, lengthening of fragment size, disruptions of ucfDNA end motifs (i.e., nucleotide sequences at fragment end) and the jagged ends (i.e., the single-stranded protruding ends). The proportion of fragment ends within DNase I hypersensitive sites (DHSs) was greatly increased in mice with the Dnase1 deletion. Such ucfDNA fragmentation pattern surrounding DHSs holds potential for classifying the human subjects with and without bladder cancer. The analysis combining various fragmentomic features could further improve the performance for bladder cancer detection, with an AUC of 0.91. This study has shed mechanistic insights into fragmentomics of ucfDNA in urine and has opened up new possibilities for applying ucfDNA fragmentomics in a clinical context. [ABSTRACT FROM AUTHOR]

O-antigen polymerase transcription and translation start signals and discussed with attention to the protein in Salmonella enterica serovar Typhinurium. The wzy (ital) transitional startpoint was at first identified by primer extension. Then the wzy (ital) promoter strength in Escherichia coli K-12 was measured and found to exceed that of the induced lac (ital) promoter.

This review focusses on unique material modification and signal amplification strategies reported in developing photoelectrochemical (PEC) biosensors with utmost sensitivity and selectivity. These successes have partly been achieved by applying photoactive materials that significantly circumvent major limitations including poor absorption of visible light, severe aggregation of nanostructures, easy charge recombination and low conductivity. In addition, several signal enhancement techniques were also demonstrated to have effectively improved the detection performance of PEC biosensors. Accordingly, we have begun this review with a systematic introduction of the concept, working principle, and characteristics of PEC biosensors. This was followed by a discussion of a range of material modification techniques, including quantum dot modification, metal/non-metal ion doping, the formation of heterojunctions and Z-scheme composites, used in the construction of PEC biosensors. Various signal amplification strategies including quantum dot sensitisation, the application of electron donors, energy transfer effect, steric hindrances of biomolecules, and the exfoliation of biomolecules from sensing surfaces are also presented in this review. Wherever possible, we have referred to relevant examples to explain and illustrate the corresponding working mechanism and effectiveness of the nanomaterials. Therefore, this review is aimed at providing an overall view on the current trend in material modification and signal amplification strategies for the development of PEC biosensors, which will aid in stimulating ideas for future progress in this field. [ABSTRACT FROM AUTHOR]

This Minireview focuses on recent advances in the applications of microelectrodes to detect and monitor targeted analytes in bioelectrochemical processes. Notably, these processes are electrochemically driven reactions that involve the detection of targets from the biological realm. Wide-ranging applications of electrochemical sensors have been reported in the last few decades in various research fields, owing to favorable attributes such as high selectivity and sensitivity, rapid analysis, simplicity, easy fabrication, and cost effectiveness. Accordingly, in this Minireview, we explore recent advances in bioelectrochemistry based on small detection probes or structures modified for a variety of analytes, exploiting multi-approach advantages of enhanced electrochemical detection surface or targeted analyte pursuit. The target analytes included in this Minireview are neurotransmitters and disease biomarkers detected using enzymatic and non-enzymatic electrode modifications. [ABSTRACT FROM AUTHOR]

Tremendous developments in electrochemical immunosensors have facilitated cost-effective, rapid and robust detection of many analytes. Among the significant developments, electrochemical immunosensors capable of simultaneously detecting several analytes have begun to emerge. In addition, recent progress in materials science and engineering has yielded nanostructured materials of various geometries that were readily exploited to provide a compatible medium for many biomolecules in immunoassays. Applications of these nanostructured materials to electrochemical immunosensor developments have significantly improved sensor performance in terms of their electrical, chemical and transport properties. This review provides a survey of innovative immunosensor developments involving a range of nanomaterials exploited in designing sensing platforms and efficient detection markers to achieve substantial signal amplifications and thereby outstanding detection characteristics. [ABSTRACT FROM AUTHOR]

In this study, our goal was to produce a self-assembled layer on a gold electrode that would enable the capture of antibodies orientated for maximum binding to their specific antigen in an immunosensor. To achieve this, the amine groups from lysine residues in protein G were initially converted to thiol groups with 2-iminothiolane. The high affinity of thiols for a gold surface facilitates the direct formation of a self-assembled protein G layer. Following this, the coated gold electrode was exposed to a solution of capture antibody (mAb1) so that these antibodies could attach to the protein G layer through their nonantigenic regions, leaving antigen binding sites available with minimal steric hindrance for binding of target analyte. A comparative study between this method and the more conventional strategy of covalently attaching a layer of nonthiolated protein G on an alkanethiol self-assembled monolayer-coated gold electrode has been performed. Based on a reduced preparation time, and an enhanced capacity for immobilized capture antibody to bind its target analyte due to a more favorable orientation, the layer of thiolated protein G was found to be a more suitable backbone for an electrochemical immunosensor. [ABSTRACT FROM AUTHOR]

In this work, a horseradish peroxidase (HRP)-encapsulated metal organic framework (MOF)@MOF nanocomposite is developed for detecting H 2 O 2 converted by dismutation of superoxide anions released from live HeLa mitochondria. Initially, an HRP-polyacrylic acid cluster is incorporated on a mesoporous, peroxidase-like Cu/Co-1,4-benzenedicarboxylate (BDC) MOF platform to avoid structural change and deactivation of HRP through its interactions with MOF metal ions. Additionally, a Cu/Co-BDC(HRP)@1,3,5-benzenetricarboxyate (BTC) core-shell MOF/MOF structure, also with peroxide-like properties, serves as a protective matrix for HRP. Then, ultrathin porous carbon shells (UPCS) are adopted to improve the electrical conductivity of the MOF@MOF. The Cu/Co-BDC(HRP)@BTC|UPCS sensing platform exhibits two linear ranges of 0.05-1 µM and 1-1000 µM with a sensitivity of 172 mA mM -1 cm -2 and 1.63 mA mM -1 cm -2 , respectively. A limit of detection of 0.057 µM, good selectivity and stability over 35 days for H 2 O 2 detection are also achieved. After treating the mitochondrial complex with specific inhibitors, amperometric results at the sensing platform confirmed complex I and III within mitochondria as the main electron leakage sites in the electron transfer chains. Therefore, this sensing platform provides a tool that may aid in predicting and even developing treatments for some oxidative stress diseases caused by mitochondrial abnormalities., (© 2024 The Author(s). Small Methods published by Wiley‐VCH GmbH.)

In this work, we have developed a nanocomposite consisting of horseradish peroxidase (HRP)-encapsulated 2D Zn-Co zeolite imidazole framework (ZIF) nanosheets strung on a ZnCoO nanowire array on a Ti support (denoted as 2D-Zn/Co-ZIF(HRP)|ZnCoO|Ti). This nanocomposite was then applied to constructing an electrochemical biosensor for detecting H 2 O 2 derived from O 2 ∙- released by mitochondria in living cells. This sensing platform shows excellent catalytic performance towards H 2 O 2 , attributable to the enzyme/metal-catalytic effect of HRP and Zn/Co-ZIF. The unique nano-string structure alleviates the aggregation of Zn/Co-ZIF nanosheets, readily exposes the catalytic active sites, protects the bioactivity of HRP, and reduces the charge/mass transfer pathway within Zn/Co-ZIF. The 2D-Zn/Co-ZIF(HRP)|ZnCoO|Ti biosensor offers two linear ranges of 0.2-10 μ M and 10-1100 μ M, a limit of detection of 0.082 μ M, a sensitivity of 3.3 mA mM -1 cm -2 , good selectivity and stability over 40 days for H 2 O 2 detection. After treating with specific mitochondrial complex inhibitors, the chronoamperometric results at the 2D-Zn/Co-ZIF(HRP)|ZnCoO|Ti confirmed complex I and III within the mitochondria electron transfer chain as the main electron leakage sites. This biosensor may contribute to the development of diagnostic health-care devices that shed light on the precaution and even treatment of oxidative stress diseases., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

This work focusses on developing a hybrid enzyme biofuel cell-based self-powered biosensor with appreciable stability and durability using murine leukemia fusion gene fragments (tDNA) as a model analyte. The cell consists of a Ti 3 C 2 T x /multiwalled carbon nanotube/gold nanoparticle/glucose oxidase bioanode and a Zn/Co-modified carbon nanotube cathode. The bioanode uniquely exhibits strong electron transfer ability and a high surface area for the loading of 1.14 × 10 -9  mol cm -2 glucose oxidase to catalyze glucose oxidation. Meanwhile, the abiotic cathode with a high oxygen reduction reaction activity negates the use of conventional bioenzymes as catalysts, which aids in extending the stability and durability of the sensing system. The biosensor offers a 0.1 fm-1 nm linear range and a detection limit of 0.022 fm tDNA. Additionally, the biosensor demonstrates a reproducibility of ≈4.85% and retains ≈87.42% of the initial maximal power density after a 4-week storage at 4 °C, verifying a significantly improved long-term stability., (© 2022 Wiley-VCH GmbH.)

A major aspect of this work is the synergistic application of a poly(diphenylbutadiene)-BiOBr composite and a gold nanoparticle-linked CeO 2 octahedron to develop a photoelectrochemical aptasensor with an easily measurable detection signal change. Specifically, poly(diphenylbutadiene) nanofiber-immobilised BiOBr flower-like microspheres were developed as a hybrid material with a heterojunction that facilitates high visible light absorption and efficient photo-generated charge separation, which are essential features for sensitive photoelectrochemical sensors. The model analyte acetamiprid was attached via its specific aptamer on the aptasensor. Separately, a gold nanoparticle-linked CeO 2 octahedron was strategically used to significantly diminish the photocurrent by impeding electron transfer at the aptasensor surface. After acetamiprid binding, the CeO 2 octahedrons were displaced from the aptasensor. This caused a weakened quenching effect and restored the photocurrent to accomplish an "on-off-on" detection mechanism. This photoelectrochemical aptasensor exhibited a detection limit of 0.05 pM over a linear range of 0.1 pM-10 μM acetamiprid. The use of an aptamer has provided good specificity to acetamiprid and anti-interference. In addition, an ∼5.8% relative standard deviation was estimated as the reproducibility of the photoelectrochemical aptasensor. Furthermore, nearly 90% of the initial photocurrent was still measurable after storing these aptasensors at room temperature for 4 weeks, demonstrating their stability., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The effects of DNASE1L3 or DNASE1 deficiency on cell-free DNA (cfDNA) methylation were explored in plasma of mice deficient in these nucleases and in DNASE1L3-deficient humans. Compared to wild-type cfDNA, cfDNA in DNASE1L3-deficient mice was significantly hypomethylated, while cfDNA in DNASE1-deficient mice was hypermethylated. The cfDNA hypomethylation in DNASE1L3-deficient mice was due to increased fragmentation and representation from open chromatin regions (OCRs) and CpG islands (CGIs). These findings were absent in DNASE1-deficient mice, demonstrating the preference of DNASE1 to cleave in hypomethylated OCRs and CGIs. We also observed a substantial decrease of fragment ends at methylated CpGs in the absence of DNASE1L3, thereby demonstrating that DNASE1L3 prefers to cleave at methylated CpGs. Furthermore, we found that methylation levels of cfDNA varied by fragment size in a periodic pattern, with cfDNA of specific sizes being more hypomethylated and enriched for OCRs and CGIs. These findings were confirmed in DNASE1L3-deficient human cfDNA. Thus, we have found that nuclease-mediated cfDNA fragmentation markedly affects cfDNA methylation level on a genome-wide scale. This work provides a foundational understanding of the relationship between methylation, nuclease biology, and cfDNA fragmentation., (© 2021 Han et al.; Published by Cold Spring Harbor Laboratory Press.)

In this work, a metallic composite with strong electrocatalytic property was designed by uniformly decorating Pt and Sn nanoparticles on the surface of TiO 2 nanorods (Pt-Sn@TiO 2 ). A detection scheme was then developed based on a dual signal amplification strategy involving the Pt-Sn@TiO 2 composite and exonuclease assisted target recycling. The Pt-Sn@TiO 2 composite exhibited an enhanced oxygen reduction current owing to the synergistic effect between Pt and Sn, as well as high exposure of Pt (111) crystal face. Initially, a Pt-Sn@TiO 2 modified glassy carbon electrode produced an amplified electrochemical signal for the reduction of dissolved oxygen in the analyte solution. Next, a DNA with a complementary sequence to a streptomycin aptamer (cDNA) was immobilised on the Pt-Sn@TiO 2 modified electrode, followed by the streptomycin aptamer that hybridised with cDNA. The corresponding oxygen reduction current was diminished by 51% attributable to the hindrance from the biomolecules. After a mixture of streptomycin and RecJ f exonuclease was introduced, both the streptomycin-aptamer complex and the cDNA were cleaved from the electrode, making the Pt-Sn and Pt (111) surface available for oxygen reduction. RecJ f would also release streptomycin from the streptomycin-aptamer complex, allowing it to complex again with aptamers on the electrode. This has then promoted a cyclic amplification of the oxygen reduction current by 85%, which is quantitatively related to streptomycin. Under optimal conditions, the aptasensor exhibited a linear range of 0.05-1500 nM and a limit of detection of 0.02±0.0045 nM streptomycin. The sensor was then used in the real-life sample detection of streptomycin to demonstrate its potential applications to bioanalysis., (Crown Copyright © 2019. Published by Elsevier B.V. All rights reserved.)

In this work, a sensitive photoelectrochemical aptasensor was developed for kanamycin detection using an enhanced photocurrent response strategy, which is based on the surface plasmon resonance effect of gold nanoparticles deposited on a 3D TiO 2 -MoS 2 flower-like heterostructure. A significant aspect of this development lies in the photoelectrochemical and morphological features of the unique ternary composite, which have contributed to the excellent performance of the sensor. To develop an aptasensor, mercapto-group modified aptamers were immobilised on the photoactive composite as a recognition unit for kanamycin. The TiO 2 -MoS 2 -AuNP composite was demonstrated to accelerate the electron transfer, increase the loading of aptamers and improve the visible light excitation of the sensor. Under optimal conditions, the aptasensor exhibited a dynamic range from 0.2 nM to 450 nM of kanamycin with a detection limit of 0.05 nM. Overall, we have successfully synergised both the electrical and the optical merits from individual components to form a ternary composite, which was then demonstrated as an effective scaffold for the development of PEC biosensors., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this work, g-C 3 N 4 and TiO 2 nanosheets were synergistically employed as a novel composite for developing a scaffold of a photoelectrochemical enzyme biosensor. In this way, we have improved the poor visible light excitation of TiO 2 and retarded the photo-generated charge recombination on g-C 3 N 4 to achieve an enhanced response at the photoelectrochemical biosensor, compared to that generated by the corresponding biosensors consisting of each individual component. Using glucose oxidase as a model enzyme, the biosensor was demonstrated to show strong visible light activity towards the enzyme mediated glucose oxidation. We have also observed a 350% enhanced photocurrent compared to that at a g-C 3 N 4 based ITO electrode. In addition, the high specific surface area and excellent biocompatibility of TiO 2 nanosheets have also positively contributed to the performance of the photoelectrochemical enzyme biosensor with a 0.05-16 mM linear range and a 0.01 mM glucose detection limit., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In this work, titanate nanotubes (TNTs), polyaniline (PANI) and gold nanoparticles (GNPs) were assembled to form a ternary composite, which was then applied on an electrode as a scaffold of an electrochemical enzyme biosensor. The scaffold was constructed by oxidatively polymerising aniline to produce an emeraldine salt of PANI on TNTs, followed by gold nanoparticle deposition. A novel aspect of this scaffold lies in the use of the emeraldine salt of PANI as a molecular wire between TNTs and GNPs. Using horseradish peroxidase (HRP) as a model enzyme, voltammetric results demonstrated that direct electron transfer of HRP was achieved at both TNT-PANI and TNT-PANI-GNP-modified electrodes. More significantly, the catalytic reduction current of H2O2 by HRP was ∼75% enhanced at the TNT-PANI-GNP-modified electrode, compared to that at the TNT-PANI-modified electrode. The heterogeneous electron transfer rate constant of HRP was found to be ∼3 times larger at the TNT-PANI-GNP-modified electrode than that at the TNT-PANI-modified electrode. Based on chronoamperometric detection of H2O2, a linear range from 1 to 1200 μM, a sensitivity of 22.7 μA mM(-1) and a detection limit of 0.13 μM were obtained at the TNT-PANI-GNP-modified electrode. The performance of the biosensor can be ascribed to the superior synergistic properties of the ternary composite., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This work is focussed on the determination of a kinetic model and the thermodynamic study of the electrochemical entrapment of the model azo dye, Acid Red 1, at conducting polypyrrole films, which is proposed as a potential green technology for treatment of azo dyes in industrial effluents. The entrapment kinetic data were found to follow a pseudosecond order model involving an intra-particle diffusion. However, the equilibrium data obtained for Acid Red 1 entrapment at polypyrrole did not obey any common surface adsorption models such as the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms. Accordingly, the entrapment process may lead to an enhanced quantity of dye embedded in a polypyrrole film, making it a more effective and efficient technology than those involving only adsorption. Similarly, dye leakage from polypyrrole film surface to a sample matrix will be easily prevented. For this treatment process, a negative ΔG° range between -1.46±0.78 and -2.94±0.24 kJ mol(-1) at the corresponding temperature range of 298-318 K, and a ΔH° of 20.5±2.5 kJ mol(-1) indicate a spontaneous and endothermic entrapment process. Also, a positive ΔS° (73.6±8.2 J mol(-1) K(-1)) reveals increased randomness of the interface and an affinity of Acid Red 1 towards polypyrrole films. A low activation energy (7.67±0.80 kJ mol(-1)) confirms a physical process for Acid Red 1 entrapment at polypyrrole films., (Copyright © 2015 Elsevier Inc. All rights reserved.)

A significant aspect of this work is the development of a multi-wall carbon nanotube (MWCNT)-titanate nanotube (TNT) nanocomposite to serve as a biocompatible scaffold with high conductivity on a biosensor surface. Unlike other scaffolds consisting of MWCNTs alone or TNTs alone, the MWCNT-TNT nanocomposite synergistically provides excellent biocompatibility, good electrical conductivity, low electrochemical interferences and a high signal-to-noise ratio. For comparison, after characterising a scaffold consisting of MWCNTs alone, TNTs alone and a MWCNT-TNT nanocomposite using several spectroscopic techniques, the analytical performance of a horseradish peroxidase (HRP) electrochemical biosensor was evaluated using cyclic voltammetry and differential pulse voltammetry. The scaffold consisting of MWCNTs alone displayed a high background charging current, a low signal-to-noise ratio and distinct electrochemical interference from its surface functional groups. In contrast, the direct electrochemistry and the catalytic capability of HRP at MWCNT-TNT modified biosensors towards H2O2 was demonstrated to be ~51% and ~144% enhanced, respectively, compared to those at TNT modified biosensors. Meanwhile, MWCNT-TNT nanocomposite modified HRP biosensors also exhibited higher sensitivity (4.42μAmM(-1)) than TNT modified HRP biosensors (1.48μAmM(-1)). The above superior performance was attributed to the improved properties of MWCNT-TNT nanocomposite as biosensor scaffold compared to its two individual components by complementing each component and synergistically sustaining the characteristic features of each component., (Copyright © 2014 Elsevier B.V. All rights reserved.)

In this paper, we demonstrate conducting polypyrrole films as a potential green technology for electrochemical treatment of azo dyes in wastewaters using Acid Red 1 as a model analyte. These films were synthesised by anodically polymerising pyrrole in the presence of Acid Red 1 as a supporting electrolyte. In this way, the anionic Acid Red 1 is electrostatically attracted to the cationic polypyrrole backbone formed to maintain electroneutrality, and is thus entrapped in the film. These Acid Red 1-entrapped polypyrrole films were characterised by electrochemical, microscopic and spectroscopic techniques. Based on a two-level factorial design, the solution pH, Acid Red 1 concentration and polymerisation duration were identified as significant parameters affecting the entrapment efficiency. The entrapment process will potentially aid in decolourising Acid Red 1-containing wastewaters. Similarly, in a cathodic process, electrons are supplied to neutralise the polypyrrole backbone, liberating Acid Red 1 into a solution. In this work, following an entrapment duration of 480 min in 2000 mg L(-1) Acid Red 1, we estimated 21% of the dye was liberated after a reduction period of 240 min. This allows the recovery of Acid Red 1 for recycling purposes. A distinctive advantage of this electrochemical Acid Red 1 treatment, compared to many other techniques, is that no known toxic by-products are generated in the treatment. Therefore, conducting polypyrrole films can potentially be applied as an environmentally friendly treatment method for textile effluents., (Copyright © 2014 Elsevier B.V. All rights reserved.)

In endoscopic sinus surgery, the anterior ethmoidal artery (AEA) is usually identified as it traverses obliquely across the fovea ethmoidalis, posterior to the bulla ethmoidalis and anterior to or within the ground lamella's attachment to the skull base. Injury to the AEA may result in hemorrhage, retraction of the AEA into the orbit, and a retrobulbar hematoma. The resulting increase in intraorbital pressure may threaten vision. Waardenburg's syndrome (WS) is a rare congenital, autosomal dominantly inherited disorder, distinguished by characteristic facial features, pigmentation abnormalities, and profound, congenital, sensorineural hearing loss. We present a case of AEAs located anterior to the bulla ethmoidalis in a 36-year-old male with WS and chronic rhinosinusitis. The anatomic abnormality was not obvious on a preoperative computed tomography scan and was discovered intraoperatively when the left AEA was injured, resulting in a retrobulbar hematoma. The hematoma was immediately identified and decompressed endoscopically without lasting complications. The AEA on the right was identified intraoperatively and preserved. The characteristic craniofacial features in WS were probably associated with the abnormal vascular anatomy. Endoscopic sinus surgeons should be aware of these potential anatomic anomalies in patients with abnormal craniofacial development.

We report a novel electrochemical method for the rapid detection of the parasitic protozoan, Cryptosporidium parvum. An antibody-based capture format was transferred onto screen-printed electrodes and the presence of horseradish peroxidase-labelled antibodies binding to the oocysts was potentiometrically detected. This method allowed the detection of 5 × 10(2)Cryptosporidium oocysts per mL in 60 min., (© 2013 Elsevier B.V. All rights reserved.)

Unlabelled: Optimal management of deep neck abscesses has been the subject of debate for more than a century: surgical drainage has been the mainstay of treatment, but recently many centres have reported successful non-operative management in selected cases., Objectives: Our objective was to review the management of deep neck abscesses in our institution and to identify characteristics that would predict successful non-operative management., Methods: A retrospective chart review from January 2001 to August 2010 was performed. Children up to age fifteen years with a CT-confirmed diagnosis of retropharyngeal or parapharyngeal abscess were included. A case-control study of small deep space neck abscesses (≤ 25 mm maximal diameter) was performed, comparing antibiotic treatment alone with antibiotics plus abscess drainage., Results: 54 children met the inclusion criteria, of whom half had abscesses ≤ 25 mm diameter. Younger children within the group with smaller abscesses were more likely to need surgical drainage (p<0.05). Of 13 children requiring operative management, ten underwent a period of antibiotic treatment and observation prior to surgery, eight (80%) had fever beyond 48 h compared with three (23%) in the non-surgical group (p<0.01). 27 children had an abscess > 25 mm diameter on CT scan, four (15%) of whom responded quickly to antibiotics and were managed non-operatively, while the rest underwent surgery. There were no significant differences between the surgical and non-surgical group characteristics with larger abscesses., Conclusion: High dose intravenous antibiotics are an effective treatment for deep space neck abscesses and may obviate the need for surgical drainage, particularly in smaller abscesses. Children who do not respond quickly to antibiotics are more likely to require surgery to achieve resolution. Children with larger abscesses may respond to antibiotic therapy alone but should be closely observed. A trial of high dose intravenous antibiotics in stable children with close observation is warranted as first line treatment, especially for small deep space neck abscesses., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

A copper monolayer was formed on a gold electrode surface via underpotential deposition (UPD) method to construct a Cu UPD|DTBP-Protein G immunosensor for the sensitive detection of 17β-estradiol. Copper UPD monolayer can minimize the non-specific adsorption of biological molecules on the immunosensor surface and enhance the binding efficiency between immunosensor surface and thiolated Protein G. The crosslinker DTBP (Dimethyl 3,3'-dithiobispropionimidate · 2HCl) has strong ability to immobilize Protein G molecules on the electrode surface and the immobilized Protein G provides an orientation-controlled binding of antibodies. A monolayer of propanethiol was firstly self-assembled on the gold electrode surface, and a copper monolayer was deposited via UPD on the propanethiol modified electrode. Propanethiol monolayer helps to stabilize the copper monolayer by pushing the formation and stripping potentials of the copper UPD monolayer outside the potential range in which copper monolayer can be damaged easily by oxygen in air. A droplet DTBP-Protein G was then applied on the modified electrode surface followed by the immobilization of estradiol antibody. Finally, a competitive immunoassay was conducted between estradiol-BSA (bovine serum albumin) conjugate and free estradiol for the limited binding sites of estradiol antibody. Square wave voltammetry (SWV) was employed to monitor the electrochemical reduction current of ferrocenemethanol and the SWV current decreased with the increase of estradiol-BSA conjugate concentration at the immunosensor surface. Calibration of immunosensors in waste water samples spiked with 17β-estradiol yielded a linear response up to ≈ 2200 pg mL(-1), a sensitivity of 3.20 μA/pg mL(-1) and a detection limit of 12 pg mL(-1). The favorable characteristics of the immunosensors such as high selectivity, sensitivity and low detection limit can be attributed to the Cu UPD|DTBP-Protein G scaffold., (Copyright © 2012 Elsevier B.V. All rights reserved.)

In this work, a novel sensing scaffold, consisting Au nanoparticle (GNP)-dotted TiO(2) nanotubes (TNTs) as the rigid material and the hydrophobic ionic liquid (HIL), 1-decyl-3-methylimidazolium tetrafluoroborate, as the entrapping agent, was applied to facilitate the electron transfer of horseradish peroxidase (HRP) on a glassy carbon electrode. GNPs were immobilised on the TNTs in our work using a one-step reduction of HAuCl(4)·3H(2)O by sodium borohydride in the presence of sodium citrate as a stabilising reagent. The morphology and composition of the as-synthesised composite materials were characterised by transmission electron microscopy, scanning electron microscopy, X-ray diffraction and Fourier-transform infrared spectroscopy. Cyclic voltammetry of HRP at the modified electrode presented a pair of reproducible, quasi-reversible redox peaks with a peak-to-peak separation of 69 mV, indicating electron transfer between HRP and composite electrode. The GNP-TNT|HIL|HRP electrode was then applied to the detection of H(2)O(2) in a pH 7.0 phosphate buffer using chronoamperometry. The biosensor exhibited a linear response in the 15-750 μM range, and a limit of detection of 2.2 μM. The biosensor also exhibited stability with 90% of the detection signal retained over a two-week duration., (Copyright © 2011 Elsevier B.V. All rights reserved.)

An ultrasensitive electrochemical immmunosensor was demonstrated to be capable of detecting the hormone cortisol down to concentrations as low as 16 pg mL(-1). In addition, the immunosensor displayed a sensitivity of 1.6 μA pg(-1) mL(-1) and a linear range up to ∼2500 pg mL(-1) of cortisol. This immunosensor was constructed based on a Au nanoparticle|dimethyl 3,3'-dithiobispropionimidate·2HCl (DTBP)-Protein G scaffold-modified Au electrode. In this work, the Au nanoparticles were used to increase the electrochemically active surface area by 28% (with a standard deviation of 3%) to enhance the quantity of the Protein G scaffold on the electrode. Thiolation of Protein G by DTBP aided in avoiding the confirmation change of Protein G, while this Protein G-DTBP component offered an orientation-controlled immobilisation of the capture antibody on the Au electrode. In this immunosensor, a monoclonal anti-cortisol capture antibody was optimally aligned by the scaffold before a competitive immunoassay between sample cortisol and a horseradish peroxidase-labelled cortisol conjugate was conducted. For quantitative analysis, square wave voltammetry was used to monitor the reduction current of benzoquinone produced from a horseradish peroxidase catalysed reaction. The improved analytical performance of our immunosensor was attributed to the synergetic effect of Au nanoparticles and the Protein G-DTBP scaffold.

A Ni(II)tetrakis(4-sulfonatophenyl) porphyrin (NiTPPS)|carbon nanotube composite electrode that shows strong catalytic and antifouling capability was developed to detect a series of phenolic endocrine compounds including bisphenol A, nonylphenol and ethynylestradiol. This electrode was fabricated by electropolymerizing NiTPPS complexes on a carbon nanotube-modified glassy carbon electrode. Optimized experimental parameters including a hydrodynamic potential of 0.7 V for flow injection analysis (FIA) and a NiTPPS surface coverage of 2.2 nmol cm(-2) (standard deviation 0.2 nmol cm(-2); n=6) were obtained for detection of the endocrine disrupting compounds. The sensor responded well to all the tested compounds with limits of detection ranging from 15 nmol L(-1) to 260 nmol L(-1) (based on three times S/N ratio) under FIA conditions. Both carbon nanotubes and NiTPPS account for the excellent performance of the composite modified electrode., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Square wave voltammetry (SWV) was compared to electrochemical impedance spectroscopy (EIS) in developing a label-free electrochemical immunosensor for the hormone estradiol. The immunosensor consists of a Au electrode anchored with a Au nanoparticle|thiolated Protein G-scaffold to facilitate immobilisation of an enhanced quantity of an almost uprightly aligned anti-estradiol capture antibody. Competitive immunoassays between an estradiol-bovine saline albumin complex and free estradiol in a sample were then promoted at the immunosensor. Next, SWV and EIS of [Fe(CN)(6)](3-/4-) were sequentially conducted at the immunosensor. SWV yielded familiar peak-shaped voltammograms with the peak currents readily employable in establishing calibration. A dynamic range up to approximately 1200 pg mL(-1) and a detection limit of 18 pg mL(-1) estradiol were achieved. In EIS, an electron transfer resistance estimated from the Nyquist plots was used in the calibration experiments. A comparable dynamic range up to approximately 1000 pg mL(-1) and a detection limit of 26 pg mL(-1) estradiol were obtained. However, a significantly 10 times longer analysis time and substantial effort were required to complete the EIS determinations relative to SWV. Moreover, a large amount of EIS data involving phase angle was collected but ignored because they would not contribute any useful information to quantitative determination. Overall, SWV was determined to be a more rapid, efficient, effective and low cost detection technique than EIS at label-free electrochemical immunosensors., (Copyright 2009 Elsevier B.V. All rights reserved.)

Low picograms of the hormone 17beta-estradiol were detected at an electrochemical immunosensor. This immunosensor features a gold nanoparticle|Protein G-(LC-SPDP)(1)-scaffold, to which a monoclonal anti-estradiol capture antibody was immobilised to facilitate a competitive immunoassay between sample 17beta-estradiol and a horseradish peroxidase-labelled 17beta-estradiol conjugate. Upon constructing this molecular architecture on a disposable gold electrode in a flow cell, amperometry was conducted to monitor the reduction current of benzoquinone produced from a catalytic reaction of horseradish peroxidase. This current was then quantitatively related to 17beta-estradiol present in a sample. Calibration of immunosensors in blood serum samples spiked with 17beta-estradiol yielded a linear response up to approximately 1200 pg mL(-1), a sensitivity of 0.61microA/pg mL(-1) and a detection limit of 6 pg mL(-1). We attribute these favourable characteristics of the immunosensors to the gold nanoparticle|Protein G-(LC-SPDP) scaffold, where the gold nanoparticles provided a large electrochemically active surface area that permits immobilisation of an enhanced quantity of all components of the molecular architecture, while the Protein G-(LC-SPDP) component aided in not only reducing steric hindrance when Protein G binds to the capture antibody, but also providing an orientation-controlled immobilisation of the capture antibody. Coupled with amperometric detection in a flow system, the immunosensor exhibited excellent reproducibility.

To achieve a high efficiency of analyte capture by a capture antibody attached to an electrochemical immunosensor, we have immobilised an analyte-specific antibody on a self-assembled layer of recombinant Protein G that was thiolated with succinimidyl-6-[3'-(2-pyridyldithio)-propionamido] hexanoate (LC-SPDP). Then two techniques were employed for conjugating a second antigen-specific antibody to alkaline phosphatase (mAb2-AP) using either LC-SPDP or the biotin-streptavidin interaction as the mode of cross-linking the antibody and enzyme. After characterising the two mAb2-AP preparations (mAb2-(LC-SPDP)-AP and mAb2-(Biotin-SA)-AP), they were each used as the signal antibody for immunosensors formatted for two-site immunoassays where the capture antibody was attached to a Protein G-(LC-SPDP) scaffold on gold electrodes. The antibodies and assays were specific for the clinically important hormone, human chorionic gonadotrophin (hCG). Protein G-(LC-SPDP) provided a stable scaffold, while mAb2-(LC-SPDP)-AP and mAb2-(Biotin-SA)-AP performed well as the signal antibodies. Immunosensors with mAb2-(Biotin-SA)-AP were characterised by a limit of detection of 216 I UL(-1) for hCG and a linear response up to approximately 2000 I UL(-1). Conversely, immunosensors with mAb2-(LC-SPDP)-AP exhibited a limit of detection of 240 I UL(-1) and a linear response up to 4000 I UL(-1).

In this work, we have developed a carbon nanotube|Ni(cyclam)-coated glassy carbon electrode to achieve minimal fouling effects and to catalyse the oxidation of the oestrogen, estradiol, during voltammetric detection. This electrode was fabricated by initially applying a Nafion-carbon nanotube mixture, and then electropolymerising Ni(cyclam) complexes on the electrode. During this process, a two-level factorial design was used to optimise experimental parameters including the amount of carbon nanotubes, the concentration of Nafion and the surface coverage of Ni(cyclam). A linear calibration plot between 0.5 and 40 microM estradiol was then obtained in synthetic laboratory standard solutions. Based on a signal-to-noise ratio of 3, a detection limit of 60 nM was estimated, which is below the typical estradiol level measured in a normal menstrual cycle. The electrodes were subsequently applied to the detection of estradiol in protein-free human serum samples. Comparable sensitivity between synthetic laboratory standard solutions and serum samples was obtained, indicating minimal interference effects from the serum matrix.

This paper describes the fabrication and evaluation of carbon nanotube (CNT) electrodes grown on stainless steel (SS) plate and wire for electrochemical sensor applications. Multi-wall carbon nanotubes with different diameters were grown on the SS plate and wire by chemical vapor deposition from an ethylene precursor. The SS provides a good electrical and mechanical connection to the CNT, and the SS is a tough substrate. The SS part of the electrode was electrically insulated from the analyte so that only the CNT were active in sensing. Cyclic voltammetry for the reduction of 6 mM K3Fe(CN)6 in a 1.0 M KNO3 supporting electrolyte was performed to examine the redox behavior of the CNT-SS electrode. The cyclic voltammograms showed sigmoidal-like shapes, indicating that mass transport around the electrodes is dominated by radial diffusion. Based on the cyclic voltammograms, the effective area of the CNT-SS electrodes and the number of individual CNTs were estimated. These results indicate that the CNT-SS plate and wire electrodes are good candidates to develop practical in vivo biosensors.

Previously, it was shown that type IVB pili encoded by the Salmonella enterica serovar Typhi pil operon are used to facilitate bacterial entry into human intestinal epithelial cells in vitro and that such entry is inhibited by purified prepilin (pre-PilS) protein (X.-L. Zhang, I. S. M. Tsui, C. M. C. Yip, A. W. Y. Fung, D. K.-H. Wong, X. Dai, Y. Yang, J. Hackett, and C. Morris, Infect. Immun. 68:3067-3073, 2000). The pil operon concludes with a simple shufflon, and a recombinase gene product (Rci) inverts DNA in the C-terminal region of the pilV gene to allow synthesis of two distinct PilV proteins, PilV1 and PilV2, which are presumptive minor pilus proteins. We show here that the type IVB pili mediate bacterial self-association, but only when the PilV1 and PilV2 proteins are not expressed. This may be achieved in wild-type serovar Typhi by rapid DNA inversion activity of the shufflon. We show that the inversion activity inhibits the expression of genes inserted between the 19-bp inverted repeats used for Rci-mediated recombination and that the activity of Rci increases when DNA is supercoiled. The data suggest that serovar Typhi self-associates under conditions (such as low oxygen tension in the gut) that favor DNA supercoiling. These results explain (i) the function of the serovar Typhi shufflon and (ii) why there are only two possible shufflon states, in contrast to the many possible states of other shufflon systems. The data further indicate that a very early step in serovar Typhi pathogenesis may be type IVB pilus-mediated self-association of bacteria in the anaerobic human small intestine prior to invasion of the human gut epithelium. The suggested type IVB pilus-dependent step in typhoid fever pathogenesis may partially explain the enhanced invasiveness of serovar Typhi for humans.