An MRI-based feasibility study of unilateral percutaneous vertebroplasty.

BACKGROUND: Percutaneous vertebroplasty (PVP) has been demonstrated to be effective in the treatment of osteoporotic fracture. The bilateral pedicular approach is the most frequently used method. However, unilateral PVP is becoming increasingly more attractive for surgeons because of its numerous benefits, including lower radiation exposure, less tissue injury, and less bone cement leakage. The purpose of this study was to investigate the anatomical feasibility of unilateral PVP by exploring the differences in the puncture success rate of the unilateral pedicular approach among different lumbar segments, between men and women, and between the left and right sides. METHODS: Punctures were simulated on magnetic resonance imaging scans of 200 patients (100 men, 100 women) at a maximum angle via a pedicular approach. The distance between the entry point and the midline of the vertebral body, the maximum puncture angle, the puncture success value, and the puncture success rate were measured and compared among different lumbar levels, between the two sexes, and between the left and right sides. RESULTS: The maximum puncture distance between the entry point and the midline gradually increased from L1 to L5, and the maximum puncture angle showed the same tendency from L1 to L5. The puncture success values for L3 and L4 were higher than those for the other lumbar levels (L1, 31.53 ± 34.45; L2, 42.15 ± 28.06; L3, 56.21 ± 18.30; L4, 56.20 ± 12.93; and L5, 48.01 ± 6.88). The puncture success rates varied from 69.5 to 98.0 % among the different lumbar levels; L3 and L4 were the two highest (L3, 95.5 %; L4, 98.0 %). There were significant differences in these measurements between men and women and between the left and right sides. CONCLUSIONS: PVP with the unilateral puncture approach appears more likely to succeed at L3 to L5 than at L1 and L2. The unilateral approach might be more suitable for men than women at levels other than L5. Additionally, the left pedicular approach might be optimal for unilateral PVP procedures.

A new dual-signalling electrochemical sensing strategy based on competitive host-guest interaction of a ß-cyclodextrin/poly(N-acetylaniline)/graphene-modified electrode: sensitive electrochemical determination of organic pollutants.

Based on the competitive host-guest interaction between a ß-cyclodextrin/poly(N-acetylaniline)/electrogenerated-graphene (ß-CD/PNAANI/EG) film and probe or target molecules, a new dual-signalling electrochemical sensing method has been developed for the sensitive and selective determination of organic pollutants. As a model system, rhodamine B (RhB) and 1-aminopyrene (1-AP) were adopted as the probe and target molecules, respectively. Due to the host-guest interaction, RhB molecules can enter into the hydrophobic inner cavity of ß-CD, and the ß-CD/PNAANI/EG-modified glassy carbon electrode displays a remarkable oxidation peak due to RhB. In the presence of 1-AP, competitive association to ß-CD occurs and the RhB molecules are displaced by 1-AP. This results in a decreased oxidation peak current of RhB and the appearance of an oxidation peak current for 1-AP, and the changes of these signals correlate linearly with the concentration of 1-AP. When the value ΔI(1-AP)+∣ΔI(RhB)∣ (ΔI(1-AP) and ΔI(RhB) are the change values of the oxidation peak currents of 1-AP and RhB, respectively) is used as the response signal to quantitatively determine the concentration of 1-AP, the detection limit is much lower than that given by using ΔI(1-AP) or ΔI(RhB) as the response signal. This dual-signalling sensor can provide more sensitive target recognition and will have important applications in the sensitive and selective electrochemical determination of electroactive organic pollutants.

Assessments of inclinations of the mandibular fossa by computed tomography in an Asian population.

This study aims to evaluate the inclinations of right and left sides the mandibular fossa in Asian population using computed tomography (CT) images and determine its effects according to the parameters of gender, age, and asymmetry. CT images of the heads of 198 Asian subjects [95 females aged 44.2 ± 20.7 years, range 11-88 years; and 103 males aged 44.5 ± 19.7 years, range 15-98 years] were selected. The following eight parameters characterizing the inclinations of the mandibular fossa were measured by medical imaging software: anterior and posterior inclinations on the left and right sides on a sagittal view, and medial and lateral inclinations on the left and right sides on a coronal view. The anterior inclination was significant steeper in males than in females on both the left and right sides. A moderate positive correlation was found between age and anterior inclinations on the left and right sides. None of the other parameters were significantly affected by age or gender. None of the parameters differed significantly between the right and left sides of the mandibular fossa in males, females, or all subjects. The anterior inclination of the mandibular fossa was affected by aging and gender becoming steeper in Asians males than females. Besides, there were no asymmetry in the right and left side inclinations of the mandibular fossa.

Using anti-malondialdehyde-modified peptide adduct autoantibodies in serum of taiwanese women to diagnose primary Sjogren's syndrome.

BACKGROUND: Sjogren's syndrome (SS) is a systemic autoimmune disease featured with a dry mouth and dry eyes. Several autoantibodies, including anti-SSA, anti-SSB, antinuclear antibodies can be detected in patients with SS. Oxidation-specific epitopes (OSEs) can be formed from malondialdehyde (MDA)-modified protein adducts and trigger chronic inflammation. In this study, our purposes were used serum levels of anti-MDA-modified peptide adducts autoantibodies to evaluate predictive performance by machine learning algorithms in primary Sjögren's syndrome (pSS) and assess the association between pSS and healthy controls. METHODS: Three novel MDA-modified peptide adducts, including immunoglobulin (Ig) gamma heavy chain 1 (IGHG1)102-131, complement factor H (CFAH)1045-1062, and Ig heavy constant alpha 1 (IGHA1)307-327 were identified and validated. Serum levels of protein, MDA-modified protein adducts, MDA, and autoantibodies recognizing unmodified peptides and MDA-modified peptide adducts were measured. Statistically significance in correlations and odds ratios (ORs) were estimated. RESULTS: The random forest classifier utilized autoantibodies combination composed of IgM anti-IGHG1102-131, IgM anti-IGHG1102-131 MDA and IgM anti-IGHA1307-327 achieved predictive performance as an accuracy of 88.0%, a sensitivity of 93.7%, and a specificity of 84.4% which may be as potential diagnostic biomarkers to differentiate patients with pSS from rheumatoid arthritis (RA), and secondary SS in RA and HCs. CONCLUSIONS: Our findings imply that low levels of IgA anti-IGHG1102-131 MDA (OR = 2.646), IgA anti-IGHG1102-131 (OR = 2.408), IgA anti-CFAH1045-1062 (OR = 2.571), and IgA anti-IGHA1307-327 (OR = 2.905) may denote developing risks of pSS, respectively.

Immunogenicity and safety of an enterovirus 71 vaccine in children aged 36-71 months: A double-blind, randomised, similar vaccine-controlled, non-inferiority phase III trial.

Background: The enterovirus 71 (EV71) vaccine produced by Wuhan Institute of Biological Products Co., Ltd. (WIBP) (B-EV71) has been given to children aged 6-35 months, and it has shown good safety, immunogenicity and efficacy. However, the administration of EV71 vaccine in children aged 36-71 months, which is another target population, needs further exploration. Methods: We conducted a double-blind, randomised, controlled, non-inferiority phase III clinical trial in children aged 36-71 months, with a further comparison group of children aged 6-35 months in China. Children aged 6-71 months with no history of hand, foot and mouth disease or prior-vaccination of EV71 vaccine were eligible and recruited. Eligible participants aged 36-71 months were randomly assigned (1:1) to receive two doses of the B-EV71 vaccine (Older-B group) or the control EV71 vaccine (C-EV71 vaccine, produced by Institute of Medical Biology, Chinese Academy of Medical Sciences) (Older-C group), administered at a 30-day interval. Eligible participants aged 6-35 months were enrolled consecutively to receive two doses of the B-EV71 vaccine (Younger-B group) at a 30-day interval. Participants, investigators and those assessing outcomes were masked to the vaccine received. Non-inferiority analyses were conducted to compare the immunogenicity of EV71 vaccine in the Older-B group with that in the Older-C and Younger-B groups. Non-inferiority margins were 10% for seroconversion rate differences and 0.5 for geometric mean titre (GMT) ratios. The primary endpoints were the GMT level and seroconversion rate of anti-EV71 neutralising antibody 30 days after the second dose of vaccination. The primary analysis was performed in the per-protocol population. Safety analyses were conducted amongst participants receiving at least one dose of vaccine. This trial was registered at Chinadrugtrials.org.cn (#CTR20192345). Findings: Between June 3 and June 30, 2020, 1600 participants were enrolled and assigned, including 625 participants in the Older-B group, 625 participants in the Older-C group and 350 participants in the Younger-B group. The seroconversion rate of anti-EV71 neutralising antibody in the Older-B group (99.66%; 95% CI: 99.18%-100.00%) was non-inferior to that of the Older-C (99.32%; 95% CI: 98.65%-99.98%) and Younger-B groups (100.00%; 95% CI: 100.00%-100.00%). The differences in seroconversion rates in the Older-B group to those in the Older-C and Younger-B groups were 0.34% (95%CI: -2.17%-2.86%) and -0.34% (95%CI: -2.78%-2.09%). The GMT of the anti-EV71 neutralising antibody in the Older-B group (693.87) was also non-inferior to that in the Older-C (289.37) and Younger-B groups (634.80). The ratios of GMTs in the Older-B group to those in the Older-C and Younger-B groups were 2.67 (95%CI: 2.00-3.00) and 1.00 (95%CI: 0.75-1.00), respectively. The incidence of any adverse event (AE) related to vaccination was similar amongst the three groups (34/625 [5.44%] in the Older-B group, 32/623 [5.14%] in the Older-C group, and 26/349 [7.45%] in the Younger-B group), with only 2 (0.57%) participants having grade 3 AEs in the Younger-B group. Fifteen (0.94%) participants from these three groups had reported serious AEs (SAEs), all of which were unrelated to vaccines. Interpretation: EV71 vaccine produced by WIBP could extend to be administered to children aged 36-71 months against EV71 infection. However, the persistence of vaccine-induced immunities needs to be further investigated. Funding: Hubei Province's young medical talent program (20191229), Hubei Province's young talent program (2021), Hubei Province's young public health talent program (2021); and the Wuhan Institute of Biological Products Co., Ltd.

Experimental platform to study heavy metal ion-enzyme interactions and amperometric inhibitive assay of Ag+ based on solution state and immobilized glucose oxidase.

The heavy metal (HM) ion-enzyme interaction is an important research topic in many areas. Using glucose oxidase (GOx) as an example, a comprehensive experimental platform based on quartz crystal microbalance and electroanalysis techniques is developed here to quantitatively study the HM ion-enzyme interactions and amperometric inhibitive assays of HM ions. The effects of some common HM ions on the bioactivities of solution-state GOx (GOx(s)), electrode surface-adsorbed GOx (GOx(ads)), and polymer-entrapped GOx (GOx(e)) are comparatively examined on the basis of anodic amperometric detection of enzymatically generated H(2)O(2). Ag(+) shows the strongest inhibition effect among the HM ions examined, and the inhibitive assays of Ag(+) based on GOx(s), GOx(ads), and GOx(e) entrapped in poly(l-noradrenalin) (PNA) give limits of detection (LOD) of 2.0, 8.0, and 5.0 nM (S/N = 3), respectively. Inhibition effects of Hg(2+), Cu(2+), and Co(2+) are detectable only at 15 µM or higher concentrations, and the other HM ions show undetectable inhibition even at 1.0 mM. The developed experimental platform allows one to quantify the number of the bound HM ions per GOx(ads) molecule at various inhibition percentages. In addition, the electrosynthesized PNA matrix to entrap GOx for an inhibitive assay of Ag(+) shows the lowest competitive affinity to HM ions and gives the highest sensitivity, as compared with several other polymer matrixes commonly used for the inhibitive assay. The suggested experimental platform is recommended for wide applications in enzymatic inhibitive assays and quantitative studies of the inhibition effects of HM ions on many other redox-event-relevant enzymes.

Exploiting metal-organic coordination polymers as highly efficient immobilization matrixes of enzymes for sensitive electrochemical biosensing.

We report on the exploitation of metal-organic coordination polymers (MOCPs) as new and efficient matrixes to immobilize enzymes for amperometric biosensing of glucose or phenols. A ligand, 2,5-dimercapto-1,3,4-thiadiazole (DMcT), two metallic salts, NaAuCl(4) and Na(2)PtCl(6), and two enzymes, glucose oxidase (GOx) and tyrosinase, are used to demonstrate the novel concept. Briefly, one of the metallic salts is added into an aqueous suspension containing DMcT and one of the enzymes to trigger the metal-organic coordination reaction, and the yielded MOCPs-enzyme biocomposite (MEBC) is then cast-coated on an Au electrode for biosensing. The aqueous-phase coordination polymerization reactions of the metallic ions with DMcT are studied by visual inspection as well as some spectroscopic, microscopic, and electrochemical methods. The thus-prepared glucose and phenolic biosensors perform better in analytical performance (such as sensitivity and limit of detection) than those prepared by the conventional chemical and/or electrochemical polymerization methods and most of the reported analogous biosensors, as a result of the improved enzyme load/activity and mass-transfer efficiency after using the MOCPs materials with high adsorption/encapsulation capability and unique porous structure. For instance, the detection limit for catechol is as low as 0.2 nM here, being order(s) lower than those of most of the reported analogues. The enzyme electrode was also used to determine catachol in real samples with satisfactory results. The emerging MOCPs materials and the suggested aqueous-phase preparation strategy may find wide applications in the fields of bioanalysis, biocatalysis, and environmental monitoring.

Primary Sjogren syndrome increases the risk of bisphosphonate-related osteonecrosis of the jaw.

The risk of bisphosphonate-related osteonecrosis of the jaw (BRONJ) in primary Sjogren syndrome (pSS) has rarely been explored. To explore the association between BRONJ and pSS, we conducted a population-based propensity-score-matched cohort study using Taiwan's National Health Insurance Research Database, including pSS patients receiving antiosteoporotic therapy and patients without pSS receiving antiosteoporotic therapy. A 1:4 matched-pair cohort based on propensity score was created. The stratified Cox proportional hazards model compared the risk of BRONJ in the pSS and non-pSS groups. In the study, 23,280 pSS patients and 28,712,152 controls were enrolled. After matching, 348 patients with pSS receiving antiosteoporotic drugs and 50,145 without pSS receiving antiosteoporotic drugs were included for analysis. The risk of developing BRONJ was 1.96 times higher in pSS patients compared with non-pSS patients after adjustment for age, sex, and comorbidities. No dose-response effect was observed in the bisphosphonate-treated pSS cohorts, documented as the cumulative defined daily doses of either < 224 or ≥ 224 (hazard ratio [HR]: 2.407, 95% confidence interval [CI] 1.412-7.790; HR: 2.143, 95% CI 1.046-4.393, respectively) increased risk of developing osteonecrosis of the jaw. In conclusion, the risk of BRONJ is significantly higher in patients with pSS compared with the general population.

Functionalization of carbon nanotubes by an ionic-liquid polymer: dispersion of Pt and PtRu nanoparticles on carbon nanotubes and their electrocatalytic oxidation of methanol.

Small beginnings: Metal nanoparticle/CNT nanohybrids are synthesized from carbon nanotubes (CNTs) functionalized with an ionic-liquid polymer. The Pt and PtRu nanoparticles with narrow size distribution (average diameter: (1.3+/-0.4) nm for PtRu, (1.9+/-0.5) nm for Pt) are dispersed uniformly on the CNTs (see images) and show good performance in methanol electrooxidation.

A label-free electrochemical immunoassay for carcinoembryonic antigen (CEA) based on gold nanoparticles (AuNPs) and nonconductive polymer film.

A simple and sensitive label-free electrochemical immunoassay electrode for detection of carcinoembryonic antigen (CEA) has been developed. CEA antibody (CEAAb) was covalently attached on glutathione (GSH) monolayer-modified gold nanoparticle (AuNP) and the resulting CEAAb-AuNP bioconjugates were immobilized on Au electrode by electro-copolymerization with o-aminophenol (OAP). Electrochemical impedance spectroscopy and cyclic voltammetry studies demonstrate that the formation of CEA antibody-antigen complexes increases the electron transfer resistance of [Fe(CN)(6)](3-/4-) redox pair at the poly-OAP/CEAAb-AuNP/Au electrode. The use of CEA antibody-AuNP bioconjugates and poly-OAP film could enhance the sensitivity and anti-nonspecific binding of the resulting immunoassay electrode. The preliminary application of poly-OAP/CEAAb-AuNP/Au electrode for detection of CEA was also evaluated.

New capillary electrophoresis-electrochemiluminescence detection system equipped with an electrically heated Ru(bpy)3(2+)/multi-wall-carbon-nanotube paste electrode.

A new capillary electrophoresis-electrochemiluminescence (ECL) detection system equipped with an electrically heated Ru(bpy)(3)(2+)/multi-wall-carbon-nanotube paste electrode (Ru(bpy)(3)(2+)/MWNTPE) was developed. Ru(bpy)(3)(2+) was immobilized in the electrode by directly mixing with the multi-wall-carbon-nanotube paste (MWNTP). This modified electrode could be electrically heated and temperature of the electrode (Te) could be accurately controlled. Tri-n-propylamine (TPrA) was used as coreactant to investigate CE-ECL signals under different conditions. Compared with the conventional electrode at room temperature, the heated electrode has been shown to provide some advantages, such as higher sensitivity, lower RSD, and decreasing width of the peak. Furthermore, wider range of capillary-to-electrode distance and larger-area electrode are a benefit to CE-ECL. In addition, this system has been applied to separation and detection of acephate and dimethoate. The results indicated that the present CE-ECL system coupled with heated modified-electrode could provide high sensitivity, wide linear range, satisfying linear relationship and excellent reproducibility.

An amperometric glucose biosensor based on glucose oxidase immobilized in electropolymerized poly(o-aminophenol) and carbon nanotubes composite film on a gold electrode.

An amperometric glucose biosensor is developed that is based on immobilization of glucose oxidase (GOD) in a composite film of poly(o-aminophenol) (POAP) and carbon nanotubes (CNT), which are electrochemically co-polymerized at a gold (Au) electrode. Because of the high surface per volume ratio and excellent electrical conductivity of CNT, the biosensor based on an Au/POAP/CNT/GOD electrode has lower detection limit (0.01 mM), larger maximum response current (0.24 mA cm(-2)) and higher sensitivity (11.4 mA M(-1) cm(-2)) than the values of the biosensor based on an Au/POAP/GOD electrode. Additionally, the biosensor shows fast response time, large response current, and good anti-interferent ability for ascorbic acid, uric acid and acetaminophen. Good reproducibility and stability of the biosensor are also observed.

Correlation between imaging characteristics and microbiology in patients with deep neck infections: a retrospective review of one hundred sixty-one cases.

BACKGROUND: This study reviews our recent experience with deep neck infections in order to propose recommendations in selecting presumptive antibiotics according to imaging characteristics and identifying predisposing factors of life-threatening complications. METHODS: The records of 161 patients treated for deep neck infections at the Department of Otolaryngology-Head and Neck Surgery, China Medical University Hospital from 2002 to 2012 were reviewed retrospectively. The demographic data, comorbidities, source of infections, complications, duration of hospital stay, imaging characteristics, and bacteriologic studies were evaluated. The involved neck space was determined by computed tomography (CT) scan with contrast. Complications included mortality and life-threatening conditions. RESULTS: The most common cause of deep neck infections in our study was odontogenic infection (20.5%), followed by pharyngo-tonsillitis (18.6%), and lymphadenitis (10.5%). The most commonly involved neck space was the submandibular space (40.9%), followed by the carotid space (37.2%), and the para-pharyngeal space (33.5%). Gas formation was detected in 31 (19.3%) cases. Infections of the different neck spaces and patients with gas formation noted on CT scan showed a specific distribution of common microorganisms. Streptococcus spp. was the most common pathogen in submandibular/sublingual space infections. Klebsiella pneumoniae infection accounted for 53.1% of peri-tonsillar/para-pharyngeal space infections, and 40% of carotid space infections. When gas formation was noted on CT imaging, anaerobic infection was the most common pathogen. Chronic kidney disease, diabetes mellitus (DM), multiple space infection, and gas formation present on CT scan were independent predictors of complications (p<0.05). CONCLUSION: The imaging characteristics and microbiology of patients with deep neck infections are correlated and can facilitate the optimal selection of antibiotics. We can administer more precise presumptive antibiotics according to the identified involved neck space on CT scan. Patients with predisposing factors of life-threatening complications require early aggressive multi-disciplinary management to prevent severe sequelae.

Sensitive electrochemical detection of nitrobenzene based on macro-/meso-porous carbon materials modified glassy carbon electrode.

A sensitive electrochemical sensor for nitrobenzene (NB) detection has been developed based on macro-/meso-porous carbon materials (MMPCMs). MMPCMs were prepared by pyrolysis of the ionic-liquid ([AEIm]BF(4)) polymer (PIL) pre-wrapped onto SiO(2) microspheres and then removal of the silica core. The morphology and structure of MMPCMs were characterized by scanning electron microscopy (SEM) and nitrogen adsorption/desorption measurements. Owing to the macro-/meso-porous structure, large specific surface area and accumulation effect of MMPCMs, the MMPCMs modified glassy carbon (MMPCMs/GC) electrode has high catalytic activity towards the reduction of NB. At the optimal pH value and accumulation time, the resulted electrochemical sensor shows satisfactory analytical performance for NB detection. The linear response range is from 0.2µM to 40µM and the detection limit is 8nM based on the signal-to-noise ratio of 3. Moreover, the MMPCMs/GC electrode exhibits good stability and reproducibility, and acceptable selectivity.

High-performance bioanode based on the composite of CNTs-immobilized mediator and silk film-immobilized glucose oxidase for glucose/O2 biofuel cells.

A high-performance bioanode based on the composite of carbon nanotubes (CNTs)-immobilized mediator and silk film (SF)-immobilized glucose oxidase (GOD) was developed for glucose/O(2) biofuel cell (BFC). Ferrocenecarboxaldehyde (Fc) was used as the mediator and covalently immobilized on the ethylenediamine (EDA)-functionalized CNTs (CNTs-EDA). GOD was cross-linked on the SF with glutaraldehyde (GA) as the cross-linking agent. The resulting electrode (CNTs-Fc/SF-GOD/glassy carbon (GC) electrode) exhibited good catalytic activity towards glucose oxidation and excellent stability. For the assembled glucose/O(2) BFC with the CNTs-Fc/SF-GOD/GC electrode as the bioanode and a commercial E-TEK Pt/C modified GC electrode as the cathode, the open circuit potential is 0.48 V and the maximum power density of 50.70 µW cm(-2) can be achieved at 0.15 V.

Chromatographic evaluation of reversed-phase/anion-exchange/cation-exchange trimodal stationary phases prepared by electrostatically driven self-assembly process.

This work describes chromatographic properties of reversed-phase/cation-exchange/anion-exchange trimodal stationary phases. These stationary phases were based on high-purity porous spherical silica particles coated with nano-polymer beads using an electrostatically driven self-assembly process. The inner-pore area of the material was modified covalently with an organic layer that provided both reversed-phase and anion-exchange properties while the outer surface was coated with nano-sized polymer beads with strong cation-exchange characteristics. This design ensured spatial separation of the anion-exchange and the cation-exchange regions, and allowed reversed-phase, anion-exchange and cation-exchange retention mechanisms to function simultaneously. Chromatographic evaluation of ions and small molecules suggested that retention of ionic analytes was influenced by the ionic strength, pH, and mobile phase organic solvent content, and governed by both ion-exchange and hydrophobic interactions. Meanwhile, neutral analytes were retained by hydrophobic interaction and was mainly affected by mobile phase organic solvent content. Depending on the specific application, selectivity could be optimized by adjusting the anion-exchange/cation-exchange capacity ratio (selectivity), which was achieved experimentally by using porous silica particles with different surface areas.

Hollow nitrogen-doped carbon microspheres pyrolyzed from self-polymerized dopamine and its application in simultaneous electrochemical determination of uric acid, ascorbic acid and dopamine.

Hollow nitrogen-doped carbon microspheres (HNCMS) as a novel carbon material have been prepared and the catalytic activities of HNCMS-modified glassy carbon (GC) electrode towards the electro-oxidation of uric acid (UA), ascorbic acid (AA) and dopamine (DA) have also been investigated. Comparing with the bare GC and carbon nanotubes (CNTs) modified GC (CNTs/GC) electrodes, the HNCMS modified GC (HNCMS/GC) electrode has higher catalytic activities towards the oxidation of UA, AA and DA. Moreover, the peak separations between AA and DA, and DA and UA at the HNCMS/GC electrode are up to 212 and 136 mV, respectively, which are superior to those at the CNTs/GC electrode (168 and 114 mV). Thus the simultaneous determination of UA, AA and DA was carried out successfully. In the co-existence system of UA, AA and DA, the linear response range for UA, AA and DA are 5-30 µM, 100-1000 µM and 3-75 µM, respectively and the detection limits (S/N = 3) are 0.04 µM, 0.91 µM and 0.02 µM, respectively. Meanwhile, the HNCMS/GC electrode can be applied to measure uric acid in human urine, and may be useful for measuring abnormally high concentration of AA or DA. The attractive features of HNCMS provide potential applications in the simultaneous determination of UA, AA and DA.

High-performance amperometric biosensors and biofuel cell based on chitosan-strengthened cast thin films of chemically synthesized catecholamine polymers with glucose oxidase effectively entrapped.

Rapid oxidation of dopamine (DA) or L-noradrenaline (NA) by K(3)Fe(CN)(6) yields poly(DA) (PDA(C)) or poly(NA) (PNA(C)) with glucose oxidase (GOx) effectively entrapped, and such an enzyme-entrapped catecholamine polymer is cast on an Au electrode followed by chitosan (CS) strengthening for biosensing and fabrication of a biofuel cell (BFC). The optimized glucose biosensor of CS/PDA(C)-GOx/Au displays an extremely high sensitivity up to 135 µA mM(-1) cm(-2), a very low limit of detection of 0.07 µM, a response time of <3 s, good suppression of interferents, striking thermostability (lifetime of 3 weeks at 60°C and over 2 months at 30°C), and high resistance to urea denaturation. The biosensor also works well in the second generation biosensing mode with p-benzoquinone (BQ) or ferrocene monocarboxylic acid (Fc) as an artificial mediator, with greatly broadened linear detection ranges (2.0 µM-48.0 mM for BQ and 2.0 µM-16.0 mM for Fc) and up to mA cm(-2)-scale glucose-saturated current density. The good permeability of artificial mediators across the enzyme film enables the quantification of the surface concentration of immobilized GOx on the basis of a reported kinetic model, and UV-Vis spectrophotometry is used to measure the enzymatic activity, revealing high enzymatic activity/load at CS/PDA(C)-GOx/Au. A BFC is also successfully fabricated with a bioanode of CS/PDA(C)-GOx/Au in phosphate buffer solution containing 100 mM glucose and 4.0 mM BQ and a carbon cathode in Nafion-membrane-isolated acidic KMnO(4), and its maximum power density of 1.62 mW cm(-2) is superior to those of most BFC hitherto reported.

Novel polymeric bionanocomposites with catalytic Pt nanoparticles label immobilized for high performance amperometric immunoassay.

We report on the aqueous preparation of novel polymeric bionanocomposites (PBNCs) with polydopamine (PDA) as an efficient matrix to support antibody and uniformly dispersed abundant Pt nanoparticles (PtNPs) for high performance sandwich-type amperometric immunoassay. We prepare three kinds of PBNCs (PBNCs 1, 2, and 3) via chemical polymerization synthesis (1) and further adsorption (2) or glutaldehyde (GA) covalent crosslinking (3) of antibody. Transmission electron microscopy, atomic force microscopy, and quartz crystal microbalance are used to characterize the PBNCs. The results show that PDA is an excellent matrix to support antibody and PtNPs due to its high biocompatibility, adsorbability, and processibility, and the thus-prepared PBNCs are of high immuno-recognition efficiency and high catalytic activity toward H(2)O(2) reduction. Then, we examine the applicability of the prepared PBNCs for sandwich-type amperometric immunosensing using a model immuno-pair of human immunoglobulin G (hIgG) and anti-hIgG, and obtain the signal by detecting the electro-reduction of H(2)O(2) catalyzed by the PtNPs label. The constructed immunosensors using PBNCs 1, 2 and 3 exhibit detection limits of 0.068, 0.037, and 0.018 ng mL(-1), respectively, being competitive with or better than the reported analogues. Our immunosensors also present good reproducibility, stability, regeneration ability, specificity, and satisfactory feasibility for target assay in clinical human serum samples. The suggested protocol for the preparation of PBNCs with high signal-transduction ability is expected to find wide bioassay applications.

An amperometric glucose biosensor based on poly(o-aminophenol) and Prussian blue films at platinum electrode.

Prussian blue (PB), as a good catalyst for the reduction of hydrogen peroxide, has been combined with nonconducting poly(o-aminophenol) (POAP) film to assemble glucose biosensor. Compared with PB-modified enzymatic biosensor, the biosensor based on glucose oxidase immobilized in POAP film at PB-modified electrode shows much improved stability (78% remains after 30 days) in neutral medium. Additionally, the biosensor, at an applied potential of 0.0 V, exhibits other good characteristics, such as relative low detection limit (0.01 mM), short response time (within 5s), large current density (0.28 mA/cm2), high sensitivity (24 mAM(-1)cm(-2)), and good antiinterferent ability. The apparent activation energy of enzyme-catalyzed reaction and apparent Michaelis-Menten constant are 34.2 KJmol(-1) and 10.5 mM, respectively. In addition, effects of temperature, applied potential used in the determination, pH value of the detection solution, and electroactive interferents on the amperometric response of the sensor were investigated and are discussed.