Structural switching aptamer-based electrochemical sensor for mycotoxin patulin detection.

In this study, an electrochemical and aptamer-based aptasensor was developed for the sensitive detection of patulin, a mycotoxin commonly found in fruits and fruit-based products. The aptasensor used an innovative structural switching signal-off platform for detecting patulin. The aptamer immobilization on screen-printed carbon electrodes was achieved through Au electrodeposition and thiol group (-SH) route. Response surface methodology was used to determine the optimal incubation times for the aptamer, blocking agent, and target molecule, which were found to be 180 min, 40 min, and 89 min, respectively. The response of the aptamer to different concentrations of patulin was measured using square wave voltammetry by exploiting the structural switching mechanism. The sensor response was determined by quantifying differences in the aptasensor's background current. The aptasensor exhibited a linear working range of 1-25 µM and a low detection limit of 3.56 ng/mL for patulin. The aptasensor's relative standard deviation and accuracy were determined to be 0.067 and 94.4%, respectively. A non-specific interaction was observed at low concentrations of two other mycotoxins, ochratoxin A and zearalenone. The interference from ochratoxin A in the measurements was below 10%. In real sample tests using apple juice, interference, particularly at low concentrations, had changed the recovery of patulin negatively with a significant effect on the structural switching behavior. Nevertheless, at a concentration of 25 ng/mL, the interference effect was eliminated, and the recovery standard deviation improved to 6.6%. The aptasensor's stability was evaluated over 10 days, and it demonstrated good performance, retaining 13.12% of its initial response. These findings demonstrate the potential of the developed electrochemical aptasensor for the sensitive detection of patulin in fruit-based products, with prospects for application in food safety and quality control.

Changes in lipid profile of obese patients undergoing sleeve gastrectomy with Transit Bipartition surgery.

The aim of this study was to investigate the short- and long-term changes in lipid profile caused by Sleeve Gastrectomy with Transit Bipartition Surgery (SG+TBS), which is one of the current metabolic surgery techniques. The study included patients who underwent SG+TBS between June 2015 and May 2019. The analyzed data included patients' demographic datas, obesity classification (Overweight, Class 1, 2, 3), and cardiovascular risk groups. Total Cholesterol (TC), triglycerides, Low-Density-Lipoprotein-Cholesterol (LDL-C), High-Density-Lipoprotein-cholesterol (HDLC) serum concentrations of patients were measured at the time of admission to the outpatient clinic and at 3 and 12 months postoperatively. The study population consisted of a total of 499 patients, 263 males and 236 females, with a mean BMI of 34.86 ± 4.90 kg/m2 and a mean age of 53.84 ± 8.93 years, who underwent SG+TBS. There was a significant decrease in the 3-month and 12-month TC levels, in the 12-month triglyceride levels of all classification groups, compared to the baseline value (p<0.001), There was also a significant decrease in the 3-month and 12-month LDL-C levels of overweight, class 1 and 2 obese patients compared to the baseline values. Although the change in the 3-month value of class 3 obese patients was insignificant, there was a significant decrease in the 12-month value, as in other obesity classification groups (p<0.05) and a significant increase in the 12-month HDL-C values for all classification groups compared to both baseline and 3-month values (p<0.05). There were significant improvements in serum lipid profiles on SG+TBS patients, which are thought to be important in reducing the risks of cardiovascular disease. KEY WORDS: Lipid profile, Obesity, Sleeve gastrectomy with Transit Bipartition.

An Overview of Biosensors for the Detection of Patulin Focusing on Aptamer-Based Strategies.

Patulin is a low molecular weight mycotoxin and poses a global problem, especially threatening food safety. It is also resistant to processing temperatures and is commonly found in fruits and vegetables. Studies have shown that it has toxic effects on animals and humans and the severity of patulin toxicity depends on the amount ingested. Therefore, the consumption of contaminated products, especially in infants and children, is important. The maximum daily intake of PAT that can be tolerated is found to be 0.4 µg/kg body weight to prevent chronic effects and the maximum residue limits in food samples were given as 50 ng/g (∼320 nM). Conventional methods for the detection of PAT have many disadvantages such as the use of expensive equipment, the need for trained personnel, and complicated sample preparation steps. To this extent, various numbers of research have been conducted on selective and sensitive detection of patulin using biosensor platforms in various media. This review presents an overview of the current literature dealing with the studies to develop patulin-specific aptamer-based biosensors and adapts various immobilization methods to increase the sensor response using different nanomaterials. Furthermore, a comparison of biosensors with conventional methods is presented using analytical performance parameters and their practicality for the detection of patulin.

Testing the validity of the brief beneficence satisfaction scale in Turkish context.

The aim of the present study was to adapt the Brief Beneficence Satisfaction Scale (BBSS) (Martela & Ryan, 2015) into Turkish context and to test its psychometric properties. The study included a community sample of 322 (61% women, 30% men and 9% unspecified). Confirmatory factor analysis verified a four-item single factor model. The BBSS-TR showed positive correlations with altruism and subjective happiness, indicating similar correlation coefficients as in the original study. The Cronbach's alpha reliability coefficient for the BBSS-TR was .85. Results concluded that the BBSS-TR is a valid and reliable measure to be used in future research. The importance of beneficence satisfaction as a new psychological concept has been discussed.

A bioresorbable peripheral nerve stimulator for electronic pain block.

Local electrical stimulation of peripheral nerves can block the propagation of action potentials, as an attractive alternative to pharmacological agents for the treatment of acute pain. Traditional hardware for such purposes, however, involves interfaces that can damage nerve tissue and, when used for temporary pain relief, that impose costs and risks due to requirements for surgical extraction after a period of need. Here, we introduce a bioresorbable nerve stimulator that enables electrical nerve block and associated pain mitigation without these drawbacks. This platform combines a collection of bioresorbable materials in architectures that support stable blocking with minimal adverse mechanical, electrical, or biochemical effects. Optimized designs ensure that the device disappears harmlessly in the body after a desired period of use. Studies in live animal models illustrate capabilities for complete nerve block and other key features of the technology. In certain clinically relevant scenarios, such approaches may reduce or eliminate the need for use of highly addictive drugs such as opioids.

An Overview of Aptamer-Based Sensor Platforms for the Detection of Bisphenol-A.

Endocrine disruptive compounds are natural or anthropogenic environmental micropollutants that alter the function of the endocrine system ultimately damaging the metabolism. Bisphenol A (BPA) is the most common of these pollutants and it is often used in epoxy coatings and polycarbonates as a plasticizer. Therefore, monitoring BPA levels in different environments is very important and challenging. In recent years, an increasing number of BPA detection methods have been proposed. This article presents a critical review of aptamer-based electrochemical, fluorescence-based, colorimetric, and several other BPA detection platforms published in the last decade. Furthermore, a statistical evaluation has been made using principle component analysis showing analytical performance parameters do not create very different clusters. Comparisons to other BPA detection methods are also presented so that the reader has an overall literature overview.

Spectroscopic ellipsometry methods for brevetoxin detection.

The spectroscopic ellipsometry (SE), and attenuated internal reflection spectroscopic ellipsometry (TIRE) are promising methods in label-free biosensing applications. An ellipsometer running under surface plasmon resonance (SPR) conditions has unique advantages over other SPR-based methods in terms of sensitivity and real-time/label-free measurement capability. In this study, both SE and TIRE-based brevetoxin B (BTX) sensors were developed using two anti-BTX aptamers reported before. A new aptamer sequence was also derived from these two antiBTX aptamers using predictive modeling tools and an exclusion method. All three antiBTX aptamers' analytical performances were quite competitive in terms of both detecting range and detection limits. However, the selectivity of the previously reported aptamers against analogs of BTX was poor at low detection ranges, especially for okadaic acid. Furthermore, the selectivity of the derived aptamer was lower than its predecessors. The sensors were capable of detecting BTX in the range of 0.05 nM-1600 nM in the TIRE and 0.5 nM-2000 nM in the SE configuration. The detection limits of the sensors were 1.48 nM (1.32 ng/mL) and 0.80 nM (0.72 ng/mL) for SE and TIRE configurations, respectively. Both configurations have been used successfully to detect BTX standards spiked into real fish and shrimp samples.

Detection Strategies of Zearalenone for Food Safety: A Review.

Zearalenone (ZEN) is a toxic compound produced by the metabolism of fungi (genus Fusarium) that threaten the food and agricultural industry belonging to the in foods and feeds. ZEN has toxic effects on human and animal health due to its mutagenicity, teratogenicity, carcinogenicity, nephrotoxicity, immunotoxicity, and genotoxicity. To ensure food safety, rapid, precise, and reliable analytical methods can be developed for the detection of toxins such as ZEN. Different selective molecular diagnostic elements are used in conjunction with different detection strategies to achieve this goal. In this review, the use of electrochemical, colorimetric, fluorometric, refractometric as well as other strategies were discussed for ZEN detection. The success of the sensors in analytical performance depends on the development of receptors with increased affinity to the target. This requirement has been met with different immunoassays, aptamer-assays, and molecular imprinting techniques. The immobilization techniques and analysis strategies developed with the combination of nanomaterials provided high precision, reliability, and convenience in ZEN detection, in which electrochemical strategies perform the best.

Sensor and Bioimaging Studies Based on Carbon Quantum Dots: The Green Chemistry Approach.

Since carbon quantum dots have high photoluminescent efficiency, it has been a desired material in sensor and bioimaging applications. In recent years, the green chemistry approach has been preferred and the production of quantum dots has been reported in many studies using different precursors from natural, abundant, or waste sources. Hydrothermal, chemical oxidation, microwave supported, ultrasonic, solvothermal, pyrolysis, laser etching, solid-state, plasma, and electrochemical methods have been reported in the literature. In this review article, green chemistry strategies for carbon quantum dot synthesis is summarized and compared with conventional methods using methodologic and statistical data. Furthermore, a detailed discussion on sensor and bioimaging applications of carbon quantum dots produced with green synthesis approaches are presented with a special focus on the last decade.

An electrochemical label-free DNA impedimetric sensor with AuNP-modified glass fiber/carbonaceous electrode for the detection of HIV-1 DNA.

In this study, a highly sensitive, electrochemical, and label-free DNA impedimetric sensor was developed using carbonized glass fiber-coal tar pitch (GF-CTP) electrodes supported with gold nanoparticles (AuNPs) for the detection of HIV-1 gene. Thiol-modified GF-CTP electrodes were prepared using amine crosslinking chemistry and AuNPs were self-assembled obtaining highly conductive nanoelectrodes, GF-CTP-ATP-Au. All steps of electrode modifications were characterized using electrochemical, spectroscopic, and microscopic methods. GF-CTP-ATP-Au electrode was then modified with a capture DNA probe (C-ssDNA) and optimized with a target DNA probe in terms of hybridization time and temperature between 30 and 180 min and 20-50 °C, respectively. Finally, the analytic performance of the developed ssDNA biosensor was evaluated using electrochemical impedance spectroscopy. The calibration of the sensor was obtained between 0.1 pM and 10 nM analyte working range. The limit of detection was calculated using signal to noise ratio of 3 (S/N = 3) as 13 fM. Moreover, interference results for two noncomplementary DNA probes were also tested to demonstrate non-specific ssDNA interactions. An electrochemical label-free DNA impedimetric sensor was successfully developed using a novel GF-CTP-ATP-Au electrode. This study suggests that highly sensitive DNA-based biosensors can be developed using relatively low-cost carbonaceous materials.

A review on nanostructure-based mercury (II) detection and monitoring focusing on aptamer and oligonucleotide biosensors.

Heavy metal ion pollution is a severe problem in environmental protection and especially in human health due to their bioaccumulation in organisms. Mercury (II) (Hg2+), even at low concentrations, can lead to DNA damage and give permanent harm to the central nervous system by easily passing through biological membranes. Therefore, sensitive detection and monitoring of Hg2+ is of particular interest with significant specificity. In this review, aptamer-based strategies in combination with nanostructures as well as several other strategies to solve addressed problems in sensor development for Hg2+ are discussed in detail. In particular, the analytical performance of different aptamer and oligonucleotide-based strategies using different signal improvement approaches based on nanoparticles were compared within each strategy and in between. Although quite a number of the suggested methodologies analyzed in this review fulfills the standard requirements, further development is still needed on real sample analysis and analytical performance parameters.

Recent advances in aptamer-based sensors for breast cancer diagnosis: special cases for nanomaterial-based VEGF, HER2, and MUC1 aptasensors.

Cancer is one of the most common and important diseases with a high mortality rate. Breast cancer is among the three most common types of cancer in women, and the mortality rate has reached 0.024% in some countries. For early-stage preclinical diagnosis of breast cancer, sensitive and reliable tools are needed. Today, there are many types of biomarkers that have been identified for cancer diagnosis. A wide variety of detection strategies have also been developed for the detection of these biomarkers from serum or other body fluids at physiological concentrations. Aptamers are single-stranded DNA or RNA oligonucleotides and promising in the production of more sensitive and reliable biosensor platforms in combination with a wide range of nanomaterials. Conformational changes triggered by the target analyte have been successfully applied in fluorometric, colorimetric, plasmonic, and electrochemical-based detection strategies. This review article presents aptasensor approaches used in the detection of vascular endothelial growth factor (VEGF), human epidermal growth factor receptor 2 (HER2), and mucin-1 glycoprotein (MUC1) biomarkers, which are frequently studied in the diagnosis of breast cancer. The focus of this review article is on developments of the last decade for detecting these biomarkers using various sensitivity enhancement techniques and nanomaterials.

The Effect of BRAF V600E Mutation on Lymph Node Involvement in Papillary Thyroid Cancer.

OBJECTIVES: Papillary thyroid cancer (PTC) is the most common well-differentiated thyroid cancer. Lymph node (LN) metastasis is frequently seen in PTC. The effect of BRAFV600E mutation on PTC-associated LN metastasis has not been clearly established. Therefore, we aimed to evaluate the effect of the BRAFV600E mutation in patients with PTC on regional LN metastasis. MATERIAL AND METHODS: Between January 2013 and 2017, sixty-three PTC patients who underwent central lymph node dissection were included into the study. The patients were divided into two groups according to the pathology results of the LN dissection, and these groups were compared for positive BRAFV600E mutations and other clinicopathological findings. RESULTS: BRAFV600E mutation was found to be more significant in the pLN1 group (p= 0.005). Multivariate analysis revealed that nodule size, microcalcifications, and BRAFV600E mutation were associated with lymph node metastasis independent of other parameters. ROC analysis also evaluated the adequacy of the BRAFV600E mutation in predicting the presence of LN involvement. AUC: 0.738 (95%CI:0.6110.866,p: 0.002). CONCLUSION: In our study, independent of other parameters, BRAFV600E gene mutation was found to be effective on lymph node involvement.

Enzymatic fuel cells with an oxygen resistant variant of pyranose-2-oxidase as anode biocatalyst.

In enzymatic fuel cells (EnFCs), hydrogen peroxide formation is one of the main problems when enzymes, such as, glucose oxidase (GOx) is used due to the conversion of oxygen to hydrogen peroxide in the catalytic reaction. To address this problem, we here report the first demonstration of an EnFC using a variant of pyranose-2-oxidase (P2O-T169G) which has been shown to have low activity towards oxygen. A simple and biocompatible immobilisation approach incorporating multi-walled-carbon nanotubes within ferrocene (Fc)-Nafion film was implemented to construct EnFCs. Successful immobilisation of the enzymes was demonstrated showing 3.2 and 1.7-fold higher current than when P2O-T169G and GOx were used in solution, respectively. P2O-T169G showed 25% higher power output (maximum power density value of 8.45 ± 1.6 µW cm-2) and better stability than GOx in aerated glucose solutions. P2O-T169G maintained > 70% of its initial current whereas GOx lost activity > 90% during the first hour of 12 h operation at 0.15 V (vs Ag/Ag+). A different fuel cell configuration using gas-diffusion cathode and carbon paper electrodes were used to improve the power output of the fuel cell to 29.8 ± 6.1 µW cm-2. This study suggests that P2O-T169G with low oxygen activity could be a promising anode biocatalyst for EnFC applications.

Electrochemical Detection of Plasma Immunoglobulin as a Biomarker for Alzheimer's Disease.

The clinical diagnosis and treatment of Alzheimer's disease (AD) represent a challenge to clinicians due to the variability of clinical symptomatology as well as the unavailability of reliable diagnostic tests. In this study, the development of a novel electrochemical assay and its potential to detect peripheral blood biomarkers to diagnose AD using plasma immunoglobulins is investigated. The immunosensor employs a gold electrode as the immobilizing substrate, albumin depleted plasma immunoglobulin as the biomarker, and polyclonal rabbit Anti-human immunoglobulin (against IgA, IgG, IgM) as the receptor for plasma conjugation. The assay showed good response, sensitivity and reproducibility in differentiating plasma immunoglobulin from AD and control subjects down to 10-9 dilutions of plasma immunoglobulin representing plasma content concentrations in the pg mL-1 range. The newly developed assay is highly sensitive, less time consuming, easy to handle, can be easily modified to detect other dementia-related biomarkers in blood samples, and can be easily integrated into portable devices.