The fabrication of a hybrid fluorescent nanosensing system and its practical applications via film kits for the selective determination of mercury ions.

Heavy metal ions especially mercury exposure have severe toxic effects on living organisms and human health. Therefore, easy, accessible, and accurate determination strategies for the selective specification of mercury ions are essential for numerous disciplines. In the presented paper, new hybrid fluorescent iron oxide nanoparticles labeled with carbazole and triazole units (CT-IONP) were prepared via surface modification for the spectrofluorimetric determination of Hg2+ in environmental samples. The structure of the new sensing system is characterized via various spectroscopic, thermal, and microscopic techniques. Under optimized conditions, the hybrid system is not only used in fully water media but also highly fluorescent which led to the "turn-off" response towards Hg2+ ion in the presence of various competitive species. The presented sensing system was successfully used for the determination of Hg2+ ions in the wide linear working range (0.02-10.00 µmol.L-1) at nanomolar levels, where the limit of detection and quantification were calculated as 7.38 and 22.14 nmol.L-1. Importantly, the practical application of hybrid material was applied by CT-IONP embedded polycaprolactone (PCL) polymer film kits. The bluish color of fabricated film kits was instantly and dramatically turned colorless-dark patterns after the addition of Hg2+ ions, which resulted in convenient and rapid film test kits for selective detection.

Label-Free Electrochemical Biosensor Platforms for Cancer Diagnosis: Recent Achievements and Challenges.

With its fatal effects, cancer is still one of the most important diseases of today's world. The underlying fact behind this scenario is most probably due to its late diagnosis. That is why the necessity for the detection of different cancer types is obvious. Cancer studies including cancer diagnosis and therapy have been one of the most laborious tasks. Since its early detection significantly affects the following therapy steps, cancer diagnosis is very important. Despite researchers' best efforts, the accurate and rapid diagnosis of cancer is still challenging and difficult to investigate. It is known that electrochemical techniques have been successfully adapted into the cancer diagnosis field. Electrochemical sensor platforms that are brought together with the excellent selectivity of biosensing elements, such as nucleic acids, aptamers or antibodies, have put forth very successful outputs. One of the remarkable achievements of these biomolecule-attached sensors is their lack of need for additional labeling steps, which bring extra burdens such as interference effects or demanding modification protocols. In this review, we aim to outline label-free cancer diagnosis platforms that use electrochemical methods to acquire signals. The classification of the sensing platforms is generally presented according to their recognition element, and the most recent achievements by using these attractive sensing substrates are described in detail. In addition, the current challenges are discussed.

A novel comparative study for electrochemical urea biosensor design: Effect of different ferrite nanoparticles (MFe2O4, M: Cu, Co, Ni, Zn) in urease immobilized composite system.

A new enzymatic electrochemical biosensor has been developed with the PANI/Nafion composite system containing ferrite nanoparticles with four different transition metals. The ferrite nanoparticles containing copper, cobalt, nickel, and zinc metals were synthesized by the co-precipitation method and their surfaces were modified with tetraethoxysilane and (3-aminopropyl) triethoxysilane to obtain -NH2 function in order to develop the purposed sensing system. The modified and unmodified ferrite nanoparticles were characterized by physically, chemically, and morphologically. Ferrite nanoparticles with suitable for enzyme immobilization were integrated on the GCE surface and covered with PANI/Nafion. According toelectrochemical measurements, it was determined that copper ferrite nanoparticles, which have the lowest bandgap value, significantly increased the biosensor performance. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to monitor biosensor production and evaluate its performance. A detection limit of 0.17 µM and a wide linear range of 0.5-45.0 µM were obtained for the urea detection with the DPV method with the sensing system (Nf/PANI/CuF/Urs). The biosensor has been successfully applied to soil and milk samples with high accuracy. In addition, it has been determined that the proposed method has good reproducibility, selectivity, and stability.

Direct and selective determination of p-coumaric acid in food samples via layered Nb4AlC3-MAX phase.

Phenolic compounds that are naturally found in food samples are not only an important part of the human diet but also useful bioactive substances for health. Among these, para-coumaric acid (p-CA) has antibacterial and antioxidant properties and is used in many industrial processes. In this study, the novel MAX-phase material, Nb4AlC3, was successfully prepared and characterized in detail with various spectroscopic, microscopic and thermal techniques. The sensor performance of Nb4AlC3 modified glassy carbon electrode (Nb4AlC3@GCE) was evaluated and analytical parameters were calculated. Experimental conditions such as pH and amount of modifier were optimized with differential pulse voltammetry (DPV) measurements. The real samples analyses of lemon, apple and pomegranate were applied for determination of p-CA with Nb4AlC3@GCE sensing system under the optimized conditions. The accuracy was evaluated by spike/recovery and high-performance liquid chromatography analysis, which accounted for high accuracy of the Nb4AlC3@GCE sensing system. The limit of detection, limit of quantification, linear working range and relative standard deviation (%) of the Nb4AlC3@GCE sensing system were determined as 0.28 and 0.85 µmol/L, 0.8-80.0 µmol/L, 3.17 %, respectively. The results showed that the proposed sensing system has the high precision at lower concentration of p-CA.

Ultrasensitive electrochemical sensor for detection of rutin antioxidant by layered Ti3Al0.5Cu0.5C2 MAX phase.

MAX phases have attracted great attention due to unique features such as thermal and electrical conductivity, easy fabrication, heat resistant, and lightweight. In this study, an easy and green method was employed to successfully develop a Ti3Al0.5Cu0.5C2 MAX phase structure, and a Ti3Al0.5Cu0.5C2 based glassy carbon electrode (GCE) was applied for the electrochemical determination of rutin antioxidants in mandarin and kiwi samples. The developed Ti3Al0.5Cu0.5C2 MAX phase was characterized by different techniques such as X-ray photoelectron spectroscopy (XPS), thermogravimetry and differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) to obtain information on the structural and morphological properties. Electrochemical methods such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed for the determination of rutin using Ti3Al0.5Cu0.5C2/GCE. The GCE modified with Ti3Al0.5Cu0.5C2 demonstrated amplified electrochemical response (ca. 4.25 times) in comparison to the bare GCE towards rutin, and exhibited ultra-sensitivity and selectivity in the presence of other interfering antioxidants. Under the optimum conditions, good linearity in the range of 0.02-50.00 µmol L-1 was obtained for rutin analysis by the Ti3Al0.5Cu0.5C2-based sensor with a limit of detection (LOD, 3σ/K) as low as 0.015 µmol L-1. The fabricated Ti3Al0.5Cu0.5C2 MAX phase was applied to determine trace levels of rutin in mandarin and kiwi samples with validation by high-performance liquid chromatography (HPLC), thus highlighting its potential for the electrochemical determination of small molecules in the agricultural field.

An electrochemical sensor for detection of trace-level endocrine disruptor bisphenol A using Mo2Ti2AlC3 MAX phase/MWCNT composite modified electrode.

Bisphenol A (BPA) is an industrially preferred material for the production of plastic and polycarbonate as well as a used material for the interior of food and beverage cans. In this study, synthesis and electrochemical sensor application of Mo2Ti2AlC3/MWCNT (multi-walled carbon nanotube) nanocomposite for BPA sensing was evaluated. Mo2Ti2AlC3 was used as MAX phase material in the design of the sensor, and MWCNT was preferred to increase conductivity and sensitivity. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to determine Mo2Ti2AlC3/MWCNT nanocomposite's electrochemical sensor performances which had LOD of 2.7 nM and LOQ of 8.91 nM in the linear working range of 0.01-8.50 µM calculated from DPV. The composite showed a single oxidation step against BPA which is diffusion-controlled and irreversible. The sensor was successfully applied for the determination of BPA in milk pack, plastic bottle, and can with recoveries ranging from 95.67% to 100.60%. In addition, sensor performance was examined through selectivity, repeatability, and reusability studies. HPLC as a standard determination method was carried out for accuracy of the voltammetric determination method in the real samples. The developed sensor could be applied to different areas from industry quality control to clinical analysis for the detection of BPA.

Evaluation of In Vivo Adhesion Properties of New Generation Polyglactin, Oxidized Regenerated Cellulose and Chitosan-Based Meshes for Hernia Surgery.

Introduction Composite meshes coated with anti-adhesive barriers have been developed by taking advantage of the robustness of polypropylene meshes for use in hernia repair. We aimed to evaluate the effects of composite meshes containing polyglactin, polycaprolactone, oxidized regenerated cellulose and chitosan on the adhesion formation. Methods Forty-two Sprague Dawley male rats were divided into six groups of seven rats according to the content of the meshes used. A defect was created on the right abdominal wall of the rats and an oval composite mesh of 2 cm in diameter was placed over the defect and fixed. The rats were sacrificed under anesthesia on the 7th postoperative day. Macroscopic and histopathological examination was performed and the incorporation of the mesh with the abdominal wall and the presence of intraabdominal adhesions were evaluated. Results When the macroscopic findings of the rats were evaluated, there was a statistically significant difference between the rat groups in terms of the distribution of peritoneal adhesion scores (p<0.05). There was no statistically significant difference between the rat groups in terms of the distribution of inflammation, fibrosis and macrophage levels (p>0.05). Conclusion It was evaluated that the development of intraabdominal adhesion and the strength of adhesion decreased when biocompatible adhesion barriers with anti-adhesive properties such as oxidized regenerated cellulose and chitosan were used in the structure of composite meshes used in hernia repair. Hemostatic and antibacterial properties of these substances are promising to create the ideal mesh.

Fluorescence determination of trace level of cadmium with pyrene modified nanocrystalline cellulose in food and soil samples.

Cadmium is one of the most toxic metal that accumulates in the human body via food chain, industrial/agricultural activites. It also has negative effects in organs such as the brain, liver and central nervous system. Therefore, International Agency for Research on Cancer is classified cadmium as "carcinogenic to humans" (group 1). In this work, novel pyrene modified nanocrystalline cellulose (NP-1) was designed as a fluorescence sensor for selective determination of Cd2+ in food and soil samples. FTIR, UV-Vis, SEM, TEM and TGA were used for structural, morphological characterizations and thermal properties of NP-1. The experimental conditions such as selectivity, pH, sensor concentration, photostability, time and interaction mechanism were examined and optimized. The LOD was determined as 0.09 µM (10.70 µg/L) which was lower than WHO's permissible limit of cadmium in plant with 0.10-60.00 µM linear working range. Validation of the present method was performed by spike/recovery test and ICP-MS, then fluorescence determination of Cd2+ in food and soil samples was succesfully applied. The results indicated that the proposed method based on "turn-on" fluorescence of NP-1 was a simple, sensitive and reliable for rapid determination of Cd2+ in real samples with high applicability and stability.

Polypropylene composite hernia mesh with anti-adhesion layer composed of polycaprolactone and oxidized regenerated cellulose.

Hernia surgeries are at the top of the general surgery operations. However, visceral adhesion, which is one of the worst complications of these operations, is still a major problem. One of the most preferred methods to prevent adhesion is the use of biomaterials. Polypropylene (PP) mesh is frequently preferred product in clinical applications owing to its mechanically robust structure against deformation within the body. However, PP meshes do not have anti-adhesive properties. Oxidized regenerated cellulose (ORC), on the other hand, is one of the most preferred products in preventing the adhesion in clinical use. ORC is not easily processable due to solubility limitations; and it must be used externally. In this study, for the first time, we designed a composite mesh structure with ORC and produced an antibacterial and anti-adhesive double-sided mesh by electro-spinning ORC micro-particles with poly(ε­caprolactone) (PCL) on PP mesh to form a composite structure. We conducted in vitro cell culture studies to determine bio-compatibility performances. We evaluated the anti-adhesion and comprehensive bio-compatibility studies through in vivo experiments. The results revealed that ORC presence and optimization of ORC degradation by coating with PCL play an important role in adhesion prevention and introduced a product prototype with efficient anti-adhesion properties.

A Polypropylene-Integrated Bilayer Composite Mesh with Bactericidal and Antiadhesive Efficiency for Hernia Operations.

Polypropylene (PP) mesh has been widely used in hernia fixation operations for more than one hundred years, and peritoneal adhesion is still one of the main complications after hernia fixation operations. For preventing peritoneal adhesion, many solutions have been offered, including gel systems, adhesion barrier membranes, and bilayer meshes. Among these, bilayer meshes come to the forefront as they serve for both hernia repair and adhesion prevention. In this study, we developed an easy and effective method to produce a multifunctional PP-integrated bilayer mesh composed of poly(lactic-co-glycolic acid) and chitosan with no need for neutralization. We made the composite mesh by electrospinning a layer onto the PP mesh. We evaluated the material characteristics, in vitro bactericidal activities, and interactions between the cells and materials. Then, we conducted in vivo efficiency studies. The results proved that the PP-integrated bilayer composite mesh is bactericidal against Escherichia coli and Staphylococcus aureus, is tissue-compatible, and supremely prevents adhesion.