Origami multiple paper-based electrochemical biosensors for pesticide detection.

Herein, we propose the first three-dimensional origami paper-based device for the detection of several classes of pesticides by combining different enzyme-inhibition biosensors. This device was developed by integrating two different office paper-based screen-printed electrodes and multiple filter paper-based pads to load enzymes and enzymatic substrates. The versatile analysis of different pesticides was carried by folding and unfolding the filter paper-based structure, without any addition of reagents and any sample treatment (i.e. dilution, filtration, pH adjustment). The paper-based platform was employed to detect paraoxon, 2,4-dichlorophenoxyacetic acid, and atrazine by exploiting the capability of these different types of pesticides (i.e. organophosphorus insecticides, phenoxy-acid herbicides, and triazine herbicide) to inhibit butyrylcholinesterase, alkaline phosphatase, and tyrosinase, respectively. The degree of inhibition correlating to the quantity of pesticides was evaluated by chronoamperometrically monitoring the enzymatic activity in the absence and in the presence of pesticides by using a portable potentiostat. To improve the sensitivity, the paper-based electrodes were modified with carbon black alone in the case of platforms for 2,4-dichlorophenoxyacetic acid and atrazine detection, or decorated with Prussian blue nanoparticles for the detection of paraoxon. The paper-based device was applied for the detection of paraoxon, 2,4-dichlorophenoxyacetic acid, and atrazine at ppb level in both standard solutions and river water sample. The accuracy of this origami multiple paper-based electrochemical biosensor was evaluated in river water by recovery studies, obtaining satisfactory values (e.g. for paraoxon 90 ±â€¯1% and 88 ±â€¯2%, for 10 and 20 ppb, respectively). The proposed three-dimensional origami paper device allows for rapid, cost-effective and accurate pesticide detection in surface water as a result of combining filter and office papers, screen-printing, wax-printing and nanomaterial technology.

Recent advances in biosensors based on enzyme inhibition.

Enzyme inhibitors like drugs and pollutants are closely correlated to human and environmental health, thus their monitoring is of paramount importance in analytical chemistry. Enzymatic biosensors represent cost-effective, miniaturized and easy to use devices; particularly biosensors based on enzyme inhibition are useful analytical tools for fast screening and monitoring of inhibitors. The present review will highlight the research carried out in the last 9 years (2006-2014) on biosensors based on enzyme inhibition. We underpin the recent advances focused on the investigation in new theoretical approachs and in the evaluation of biosensor performances for reversible and irreversible inhibitors. The use of nanomaterials and microfluidic systems as well as the applications of the various biosensors in real samples is critically reviewed, demonstrating that such biosensors allow the development of useful devices for a fast and reliable alarm system.

Cadmium determination in natural water samples with an automatic multisyringe flow injection system coupled to a flow-through screen printed electrode.

Heavy metals, as cadmium, attract a rising attention in environmental studies due to their increasing release by human activities and acute toxicity. In situ analytical methods are needed to minimize current uncertainties caused by the transport and conservation of samples. Here, we present the completely automatic determination of Cd in natural waters using a newly developed screen printed electrode sensor (SPE), inserted in a homemade purpose-built flow cell coupled to a Multi-Syringe Flow Injection Analysis system (MSFIA). The working electrode of SPEs was constituted by a carbon film modified with Nafion. Cd was plated on an in situ bismuth film and determined using Square Wave Anodic Stripping Voltammetry. Different chemical conditions of deposition and stripping were studied. A sample/acetic buffer mixture was found to be a well suited medium to form the Bi film and perform the analysis. Cd was quantified via calibration by on line standard additions. The limit of detection was found to be 0.79µgL(-1), well below the limit stipulated by the European directive (5µgL(-1)). Good sample throughput (14h(-1)) and low consumption of reagent and sample (1.3mL) were also obtained in line with previous works in Cd flow analysis.

May etanercept and PTH (1-34) association heal erosions in early rheumatoid arthritis? A pilot study.

INTRODUCTION: Rheumatoid arthritis (RA) is characterized by the formation in the joints of an inflammatory tissue, which causes the appearance of localized erosions on the margins of the joints. The molecular mechanism that causes the bone erosion is multifactorial. Inflammatory cytokines imbalance and OPG-RANK-L system are involved. OBJECTIVE OF THE STUDY: The aim of the study is to evaluate the possibility of inducing healing or reduction in the number of erosions in Rheumatoid Arthritis patients treated with anti-TNF-alpha adding Teriparatide (PTH1-34) to standard treatment with anti-TNF. PATIENTS AND METHODS: Twenty adult patients with active RA diagnosed according to American Rheumatism Association (ARA) criteria at least 6 months before study begin were enrolled. Only patients affected by established RA (6 to 18 months from symptoms beginning) were recruited. Eligible patients were randomized to receive a standard dosage of etanercept (50 mg/week) or etanercept at same dosage with an addition of teriparatide (20 mg). Evaluation of eventual healing of arthritic erosions by magnetic resonance imaging was performed at time zero and then at twelve months. The following evaluation was assessed at baseline and after 12 months according to the Outcome Measures in Rheumatology Clinical Trials (OMERACT) definitions: number of erosion and presence or absence of synovitis, effusion and bone oedema. A comparative examination of quantitative and qualitative assessment of each parameter was applied. Plain radiographs of the hands were obtained at baseline and 52 weeks. Radiographs were scored blindly using the van der Heijde modification of the Sharp method. Safety of each treatment was evaluated by means of the adverse events (AES) evaluation and report. RESULTS: There were no significant differences in baseline characteristics between the groups. The study did not achieve its primary endpoint of healing erosions. In the active arm no healing of erosions was found. At 52 weeks, there were no new MRI erosions in two arms. Bone oedema scores were significantly improved at 52 weeks in favour of both treatments versus baseline scores, without inter-groups differences. X-ray patterns were unchanged in all patients of both groups. No new erosions or previous erosions' healing were observed. No AEs were reported. Patients from both groups demonstrated a significant reduction in the DAS 28 scores at 52 weeks (p < 0.005) if compared with baseline values. CONCLUSIONS: These data confirm rapid control of inflammation and MRI damage benefits after Etanercept administration without a significant improvement in MRI findings after concomitant addition of teriparatide. Even though these results could seem to suggest to avoid the simultaneous use of these two drugs to treat RA erosions, further studies might be suggested to asses if sequential adminstration of an anabolic agent such as Teriparatide, after achieving clinical remission, may be able to improve bone damage.

Acetylcholinesterase biosensor based on single-walled carbon nanotubes--Co phtalocyanine for organophosphorus pesticides detection.

A simple and reliable technique has been developed for the construction of an amperometric acetylcholinesterase biosensor based on screen-printed carbon electrodes. For the first time, one-step modification using single-walled carbon nanotubes and Co phtalocyanine has been proposed to decrease the working potential and to increase the signal of thiocholine oxidation. The biosensor developed made it possible to detect 5-50 ppb of paraoxon and 2-50 ppb of malaoxon with detection limits of 3 and 2 ppb, respectively (incubation 15 min). The biosensor showed high reproducibility when measurements of the substrate and inhibitor were performed (R.S.D. about 1% and 2.5%, respectively). The reliability of the inhibition measurements was confirmed by testing spiked samples of sparkling and tape waters.

An acetylcholinesterase biosensor for determination of low concentrations of Paraoxon and Dichlorvos.

The characterization of an economic and ease-to-use carbon paste acetylcholinesterase (AChE) based biosensor to determine the concentration of pesticides Paraoxon and Dichlorvos is discussed. AChE hydrolyses acetylthiocholine (ATCh) in thiocoline (TC) and acetic acid (AA). When AChE is immobilized into a paste carbon working electrode kept at +410 mV vs. Ag/AgCl electrode, the enzyme reaction rate using acetylthiocholine chloride (ATCl) as substrate is monitored as a current intensity. Because Paraoxon and Dichlorvos inhibit the AChE reaction, the decrease of the current intensity, at fixed ATCl concentration, is a measure of their concentration. Linear calibration curves for Paraoxon and Dichlorvos determination have been obtained. The detection limits resulted to be 0.86 ppb and 4.2 ppb for Paraoxon and Dichlorvos, respectively, while the extension of the linear range was up 23 ppb for the former pesticide and up to 33 ppb for the latter. Because the inhibited enzyme can be reactivated when immediately treated with an oxime, the biosensor reactivation has been studied when 1,1'-trimethylene bis 4-formylpyridinium bromide dioxime (TMB-4) and pyridine 2-aldoxime methiodide (2-PAM) were used. TMB-4 resulted more effective. The comparison with the behavior of similar AChE based biosensors is also presented.

A thionine-modified carbon paste amperometric biosensor for catechol and bisphenol A determination.

A thionine-modified carbon paste electrode for catechol and Bisphenol A (BPA) detection is presented. Graphite powder was modified by adsorbing thionine as electrochemical mediator. The electrochemical response of the modified carbon paste electrode (CPE) was determined before electrode modification with tyrosinase. Then, tyrosinase was added in order to assemble a biosensor. Once established the best operative conditions, an interelectrode reproducibility around 7% was obtained and the resulting biosensor showed improved sensitivities and (S=139.6+/-1.1 nA/microM for catechol and S=85.4+/-1.5 nA/microM for BPA) in comparison with the biosensor constructed without thionine (S=104.4+/-0.5 nA/microM for catechol and S=51.1+/-0.6 nA/microM for BPA) and low detection limits (0.15 microM for both the electrodes and analytes). Also the comparison with the results reported in the literature showed higher sensitivity and lower detection limit for our biosensor. Moreover the functioning of the thionine-tyrosinase CPE was validated following a biodegradation process of water polluted by BPA and comparing the time changes of BPA concentration inferred by the biosensor calibration curve and those determined by means of HPLC measurements.

Construction, assembling and application of a trehalase-GOD enzyme electrode system.

Trehalose is a disaccharide important in foods, serving as a glucose source in many and also as an additive in the food preparation. Because of its peculiar physico-chemical properties it plays an important role as preservative in drying and deep-freezing treatments. A new biosensor for trehalose determination has been realized by means of a flow system, based on a reactor in which the trehalase enzyme catalyses its hydrolysis into two alpha,d-glucose molecules, and a GOD (glucose oxidase) amperometric biosensor is employed for the glucose determination. The optimum operative conditions have been laid out and a particular attention has been paid to the immobilization procedure of the two enzymes. The electrode used is of the SPE (screen-printed electrode) type and has been activated with the Prussian Blue (PB) and then assembled using GOD immobilized with Nafion. The reactor has been prepared with the trehalase enzyme chemically immobilized on an Immunodyne ABC membrane. As demonstration of its utility, the biosensor has been tested on a real sample of Boletus edulis mushroom.

Enzymatic determination of BPA by means of tyrosinase immobilized on different carbon carriers.

Different tyrosinase carbon paste modified electrodes to determine bisphenol A (BPA) concentration in aqueous solutions have been constructed. Variables examined were in the carbon paste composition and in particular: (i) the immobilized enzyme amount; (ii) the carbon type (powder, single or multi-walled nanotubes); (iii) the nature of the pasting oil (mineral oil, hexadecane and dodecane). For each biosensor type the amperometric response was evaluated with reference to the linear range and sensitivity. Constant reference has been made to the amperometric signals obtained, under the same experimental conditions, towards the catechol, a specific phenolic substrate for tyrosinase. The most efficient biosensors were those constructed by using the following composition for the carbon paste: 10% of tyrosinase, 45% of single wall carbon nanotubes (SWCN) and 45% of mineral oil. This biosensor formulation displayed the following electrochemical characteristics: a sensitivity equal to 138 microA/mM, LOD of 0.02 microM (based on three times the S/N ratio), linear range of 0.1-12 microM and response time of 6 min. This experimental work represents a first attempt at construction of a new carbon nanotube-tyrosinase based biosensor able to determine the concentration of BPA, one of the most ubiquitous and hazardous endocrine disruptors which can pollute the drinking and surface water, as well as many products of the food chain.

Post-transplant hepatic complications: Imaging findings.

Transplantation is considered definitive therapy for acute or chronic irreversible pathologies of the liver, and the increased survival rates are mainly due to improved immunosuppressive therapies and surgical techniques. However, early diagnosis of possible graft dysfunction is crucial to liver graft survival. Diagnostic imaging plays an important role in the evaluation of the liver before and after transplant and in the detection of complications such as vascular and biliary diseases, acute and chronic rejection and neoplastic recurrence. Integrated imaging using color-Doppler, CT, MRI and traditional x-ray reach a high level of sensitivity and specificity in the management of transplanted patients.

SommarioIl trapianto epatico è il migliore trattamento per l'insufficenza epatica terminale.Il miglioramento della sopravvivenza postoperatoria è dovuta soprattutto al perfezionamento della terapia immunosoppressiva e delle tecniche chirurgiche.L'imaging radiologico riveste un ruolo importante sia per la valutazione preoperatoria dei pazienti, identificando eventuali varianti anatomiche che richiedono una modifica della tecnica chirurgica, sia per la diagnosi e la terapia precoce delle complicanze post trapianto, contribuendo alla riduzione della mortalità e della morbilità.

Combined analysis of E-cadherin gene (CDH1) promoter hypermethylation and E-cadherin protein expression in patients with gastric cancer: implications for treatment with demethylating drugs.

BACKGROUND: Hypermethylation is studied as a new, relevant mechanism for silencing tumor suppressor genes. It is a potentially reversible epigenetic change and it is the target of novel anticancer compounds with demethylating activity. In this perspective, we investigated E-cadherin gene (CDH1) promoter hypermethylation in gastric carcinomas and its correlation with E-cadherin protein expression. METHODS: Consecutive cases of gastric carcinoma with assessable paraffin-embedded tumor blocks and paired normal mucosa were considered eligible for study entry. CDH1 promoter hypermethylation and E-cadherin protein expression were determined by methylation-specific polymerase chain reaction and immunohistochemistry, respectively. RESULTS: CDH1 promoter hypermethylation was found in 20 out of 70 gastric carcinomas and the epigenetic change occurred in the early, as well as in the locally advanced disease. In five cases, hypermethylation was also detected in the normal mucosa. Eighteen out of 20 hypermethylated tumors were of the diffuse histotype (P=0.0001). Of 24 tumors with reduced or negative E-cadherin expression, 19 were hypermethylated and 5 were unmethylated (P=0.0001). CONCLUSIONS: CDH1 promoter hypermethylation frequently occurs in gastric carcinomas of the diffuse histotype and it is significantly associated with downregulated E-cadherin expression. The knowledge on the hypermethylation status of tumor suppressor genes may be relevant to the development of demethylating drugs and novel chemopreventive strategies in solid tumors.

[Computed tomography evaluation of metastasis of cutaneous melanoma]. / Valutazione con Tomografia Computerizzata delle metastasi da melanoma cutaneo.

PURPOSE: To assess the value of Computed Tomography (CT) in the diagnosis and in morphologic characterization of metastatic melanoma. MATERIALS AND METHODS: The data of total body CT of 124 consecutive patients with melanoma having a Breslow index 1 mm or a positive sentinel lymph node have been retrospectively reviewed. RESULTS: The CT scan showed loco-regional and/or distant metastases in 36 patients (39%). Ten of these (28%) had metastases only to lymph nodes, whereas 26 patients (72%) had multiple metastases. Nodal, pulmonary, brain, subcutaneous, hepatic, adrenal, bone, gastrointestinal, breast and abdominal wall metastases were detected in 80.6%, 47.2%, 25%, 25%, 16.7%, 13.9%, 11.1%, 5.6%, 5.6% and 2.8% of the patients respectively. All the patients with metastases also had a positive sentinel lymph nodes and/or symptoms of metastatic disease. CONCLUSIONS: CT fails to reveal any characteristic feature of metastatic melanoma, but it is of value in the diagnosis of loco-regional and distant metastases in III stage disease.