New potentiometric PVC membrane electrode for Ferric Reduction Antioxidant Power assay.

In this study, a fast, reproducible and simple-to-apply a new potentiometric determination method was developed for the evaluation of iron (III) reducing power (FRAP), one of the antioxidant capacity tests. For this purpose, an all-solid-state contact iron (III)-selective poly vinyl chloride (PVC) membrane electrode (FRAP-PME) has been developed. In the structure of the developed polymeric membrane electrode (PME), Fe(II)-quercetin compound was used as the active ingredient. It was obtained that PME exhibits a linear potentiometric behavior against the concentration change of Fe(III) ion between 1.0 × 10-1-1.0 × 10-5 mol L-1 and the detection limit is 8.0 × 10-6 molL-1. PME showed a very rapid potential response (40-45 s) and was found to have a very high selectivity towards Fe(III) ion in the presence of other species that might interfere. The proposed potentiometric method has been successfully applied to evaluate the iron (III) reducing power of plant extracts.

Chitosan/luminol/AgNPs nanocomposite for electrochemiluminescent determination of prostate-specific antigen.

A green, environmentally friendly protocol was developed for ultrasensitive and highly specific recognition of prostate-specific antigen (PSA) based on the ECL effect of luminol supported by chitosan-silver nanoparticles (CS/AgNPs) nanocomposites. The transducing surface was fabricated through two consecutive electrodeposition steps of gold nanoparticles (AuNPs) and chitosan (CS)-AgNPs-luminol electrochemiluminophore onto the glassy carbon electrode. In addition to an appropriate desirable biocompatibility, the electrochemical synthesis presents low-cost preparation and ultrafast determination opportunity. AgNPs play a linking role to attach luminol, as an ECL agent to the CS support via donor-acceptor bonds between Ag atoms with NH groups of luminol and CS. Also, AgNPs can amplify the ECL intensity as a consequence of their excellent specific surface area and conductivity. To enhance the performance of the nanobiosensor, AuNPs were also used due to their high-specific surface area and excellent affinity toward amine groups of CS. Based on this high-performance analysis strategy, ultrasensitive screening of PSA was attained with a desirable limit of detection of 0.6 ng mL-1 and a broad linear range between 1 pg mL-1 and 10 ng⋅mL-1 (R2=0.994). Approximately, the same results were recorded for the analysis of the unprocessed serum samples of patients with prostate cancer at different stages. This research provided significant insight into electrografting methods to construct ECL transducers for clinical monitoring of PSA and other tumor biomarkers in the clinical setting.

Electrochemical biosensors in exosome analysis; a short journey to the present and future trends in early-stage evaluation of cancers.

The tumor microenvironment consists of a multiplicity of cells such as cancer cells, fibroblasts, endothelial cells, and immune cells within the specific parenchyma. It has been indicated that cancer cells can educate other cells within the tumor niche in a paracrine manner by the release of nano-sized extracellular vesicles namely exosomes (Exo), resulting in accelerated tumor mass growth. It is suggested that exosomal cargo with remarkable information can reflect any changes in metabolic and proteomic profiles in parent tumor cells. Therefore, exosomes can be touted as prognostic, diagnostic, and therapeutic elements with specific biomarkers in patients with different tumor types. Despite the advantages, conventional exosome separation and purification protocols are time-consuming and laborious with low abnormal morphology and purity rate. During the last decades, biosensor-based modalities, as emerging instruments, have been used to detect and analyze Exo in biofluids. Due to suitable specificity, sensitivity, and real-time readout, biosensors became promising approaches for the analysis of Exo in in vitro and in vivo settings. The inherent advantages and superiority of electrochemical biosensors in the determination of tumor grade based on exosomal cargo and profile were also debated. Present and future challenges were also discussed related to the application of electrochemical biosensors in the clinical setting. In this review, the early detection of several cancer types associated with ovaries, breast, brain, colon, lungs, T and B lymphocytes, liver and rare types of cancers were debated in association with released exosomes.

Considerations on the Controlled Delivery of Bioactive Compounds through Hyaluronic Acid Membrane.

(1) Background: The standard treatment for periodontal disease, a chronic inflammatory state caused by the interaction between biofilms generated by organized oral bacteria and the local host defense response, consists of calculus and biofilm removal through mechanical debridement, associated with antimicrobial therapy that could be delivered either systemically or locally. The present study aimed to determine the effectiveness of a hyaluronic acid membrane matrix as a carrier for the controlled release of the active compounds of a formulation proposed as a topical treatment for periodontal disease, and the influence of pH on the complex system's stability. (2) Methods: The obtained hyaluronic acid (HA) hydrogel membrane with dispersed melatonin (MEL), metronidazole (MZ), and tetracycline (T) was completely characterized through FTIR, XRD, thermal analysis, UV-Vis and fluorescence spectroscopy, fluorescence microscopy, zeta potential and dielectric analysis. The MTT viability test was applied to check the cytotoxicity of the obtained membranes, while the microbiological assessment was performed against strains of Staphylococcus spp. and Streptococcus spp. The spectrophotometric investigations allowed to follow up the release profile from the HA matrix for MEL, MZ, and T present in the topical treatment considered. We studied the behavior of the active compounds against the pH of the generated environment, and the release profile of the bioactive formulation based on the specific comportment towards pH variation. The controlled delivery of the bioactive compounds using HA as a supportive matrix was modeled applying Korsmeyer-Peppas, Higuchi, first-order kinetic models, and a newly proposed pseudo-first-order kinetic model. (3) Results: It was observed that MZ and T were released at higher active concentrations than MEL when the pH was increased from 6.75, specific for patients with periodontitis, to a pH of 7.10, characterizing the healthy patients. Additionally, it was shown that for MZ, there is a burst delivery up to 2.40 × 10-5 mol/L followed by a release decrease, while for MEL and T a short release plateau was recorded up to a concentration of 1.80 × 10-5 mol/L for MEL and 0.90 × 10-5 mol/L for T, followed by a continuous release; (4) Conclusions: The results are encouraging for the usage of the HA membrane matrix as releasing vehicle for the active components of the proposed topical treatment at a physiological pH.

Monitoring microalgal growth of Chlorella minutissima with a new all solid-state contact nitrate selective sensor.

As third generation feedstock, microalgae are microorganisms that can grow only in the optimum conditions. There are parameters including the concentration of macro and microelements in nutrient solution, pH, temperature and light intensity that have significant impact on microalgal growth. In recent years, various sensing devices have been developed for sensitive measurement of these parameters during microalgal growth. In this study, a new potentiometric nitrate selective sensor was developed to indicate the nitrate uptake of microalgae and the effect of nitrate nutrient on microalgal growth, specifically, and this sensor was successfully applied to determine nitrate concentration in medium during microalgal growth. Moreover, the effects of nitrate, carbonate and phosphate concentration in the growth medium on biomass production of Chlorella minutissima were investigated by using Box-Behnken design method, and optimum conditions were determined for the highest biomass production of microalgae. As a result of the experiments, it was seen that the highest C. minutissima production was achieved using the medium consist of 2.63 g/L NaNO3 , 0.35 g/L Na2 CO3 and 0.4 g/L KH2 PO4. Statistically, it was observed that there was a proportional relationship between the microalgae production and investigated parameters such as carbon, nitrogen and phosphate amounts of culture mediums. The electrode showed a wide linear range between 1.0 × 10-1 and 5.0 × 10-5  M with a detection limit of the 5 × 10-6  M and the response time was found as 10 s. The results showed that developed nitrate selective sensor could be successfully applied for continuous measurement of nitrate in microalgal productions at reduced cost.

Development and comparison of various rod-shaped mini-reference electrode compositions based on Ag/AgCl for potentiometric applications.

Several fundamentally similar, miniaturized solid-state reference electrode designs, and their fabrication and comparison are described in this article. All electrodes were based on Ag/AgCl as their reference element. The best electrode (a three-layer assembly with graphite oxide, epoxy, and hardener as the framework providers and with well-mixed micro-Ag particles in the bottom layer, AgCl in the middle layer, and fine KCl powder in the top layer) exhibited satisfactory short-term performance to replace a commercial reference electrode in many cases and was rigorously tested in terms of pH response, long-term leakage, and the effect of oxygen to better evaluate its characteristics. To assess the electrode's performance in medically important studies, cytotoxicity experiments and tests in artificial saliva were also conducted. All tests demonstrated that our best reference electrode was stable and had a long shelf life.

Potentiometric urea biosensors.

Excess nitrogen in the body is converted to urea in the liver, and urea is disposed as a waste product in urine. Urea concentration can change in body fluids such as blood due to the presence of certain disorders. Therefore, the determination of urea is of high importance in various areas including medical diagnosis, as well as food quality control and environmental monitoring. Potentiometric sensors have certain advantages over their alternatives, such as rapidity, portability, cost effectiveness, high sensitivity, easy operation and simple apparatus. Potentiometric urea biosensors based on enzyme urease have been developed using various materials including nanoparticles and films, and also using different methodologies. In this review, we covered potentiometric urea biosensors reported in the literature, and touched upon their certain structure characteristics and performance parameters including detection limit, working concentration range, response time and lifetime, all of which are of practical importance. Each potentiometric urea biosensor has its own advantages and drawbacks, thus the selection of appropriate method depends on the sample to be analyzed, its urea concentration range and other requirements of the particular application. Further research is needed in order to optimize the performance of these devices and to broaden their applicability.

Exopolysaccharides from microalgae: production, characterization, optimization and techno-economic assessment.

Microalgae cultivation for exopolysaccharide production has getting more attention as a result of their high hydrocarbon biosynthesis skill. The aim of this study is to examine the exopolysaccharide production potential of different species of microalgae. In this context, exopolysaccharides were produced from Chlorella minutissima, Chlorella sorokiniana and Botryococcus braunii microalgae and the effects of carbon and nitrogen content in the growth medium and illumination time on exopolysaccharide production were analyzed statistically using Box-Behnken experimental design. In addition, techno-economic assessment of exopolysaccharide production were also performed by using the most productive microalgae and optimum conditions determined in this study. As a result of the experiments, it was seen that C. minutissima, C. sorokiniana and B. braunii produced 0.245 ± 0.0025 g/L, 0.163 ± 0.0016 g/L and 0.117 ± 0.0007 g/L exopolysaccharide, respectively. Statistically, it was observed that there was an inverse relationship between the exopolysaccharide production and investigated parameters such as illumination period and carbon and nitrogen amounts of culture mediums. The techno-economic assessment comprising microalgal exopolysaccharide (EPS) bioprocess was carried out, and it showed that the system can be considered economically viable, yet can be improved with biorefinery approach.

The Implication of Reactive Oxygen Species and Antioxidants in Knee Osteoarthritis.

Knee osteoarthritis (KOA) is a chronic multifactorial pathology and a current and essential challenge for public health, with a negative impact on the geriatric patient's quality of life. The pathophysiology is not fully known; therefore, no specific treatment has been found to date. The increase in the number of newly diagnosed cases of KOA is worrying, and it is essential to reduce the risk factors and detect those with a protective role in this context. The destructive effects of free radicals consist of the acceleration of chondrosenescence and apoptosis. Among other risk factors, the influence of redox imbalance on the homeostasis of the osteoarticular system is highlighted. The evolution of KOA can be correlated with oxidative stress markers or antioxidant status. These factors reveal the importance of maintaining a redox balance for the joints and the whole body's health, emphasizing the importance of an individualized therapeutic approach based on antioxidant effects. This paper aims to present an updated picture of the implications of reactive oxygen species (ROS) in KOA from pathophysiological and biochemical perspectives, focusing on antioxidant systems that could establish the premises for appropriate treatment to restore the redox balance and improve the condition of patients with KOA.

A highly sensitive electrochemiluminescence cytosensor for detection of SKBR-3 cells as metastatic breast cancer cell line: A constructive phase in early and precise diagnosis.

Ultrasensitive monitoring of cancer cells, especially metastatic ones, has a great interest in human medicine. Despite the early diagnosis of diseases, there is an essential need for any prediction in the severity of side effects for therapeutic outcomes like metastasis. Therefore, the inhibition of cancer cells metastasis to other organs is of utmost importance for cancer suffering patients. In this regard, we developed an electrochemiluminescence (ECL)-based cytosensor for the quantification of metastatic breast cancer cells, namely SKBR-3. Silica-based mesoporous materials have a great potential for application in ECL biosensors due to their high loading capacity and mechanical strength. Herein, a silica-based electrode was prepared via in situ electrosyntheses of mesoporous silica as an environmentally friendly approach. In this protocol, luminol (as luminophore) was combined with chitosan (as attachment biomolecule) to produce a stable lumino-composite film on the electrode surface. At the optimum experimental conditions, the lower limit of quantitation (LLOQ) and linear dynamic range (LDR) were obtained as 20 cells/mL and 20 to 2000 cells/mL, individually. The specificity was desirably examined in the presence of other breast cancer cell lines such as MCF-7 and MDA-MB-231, as a model of early-stage and invasive phases of breast cancer cells. The repeatability was successfully examined for five repetitive measurements and the acceptable relative standard deviation (RSD) was calculated as about 1.6% for 500 cells/mL. As a proof of concept, the presented cytosensor has a high ability to use in clinical laboratories for the detection and separation of metastatic cells via the combination with microfluidic systems.

Internet of Things Implementation of Nitrate and Ammonium Sensors for Online Water Monitoring.

In this work, we proposed a new wireless sensor to contribute to research aimed at continuous monitoring of nitrate and ammonium in water, which as leading agents of water pollution have become the source of a serious problem today. In this research, a well-implemented application of an electroanalytical sensor was achieved by combining it with the internet of things (IoT) concept, which is the most modern technique for wireless data collection. We developed a portable IoT system and ion-selective nitrate and ammonium electrodes and monitored the nitrate and ammonium levels of the water online. The system was produced in a low-cost manner (under $25) and it enabled data acquisition without energy-related problems, thanks to the support of solar energy and mobile power bank. The recovery rates of the sensors were tested with the standard addition method and response was obtained between 101.74 and 147.01%.

Control of Nanostructured Polysulfone Membrane Preparation by Phase Inversion Method.

The preparation of membranes from polymer solutions by the phase inversion method, the immersion-precipitation technique has proved since the beginning of obtaining technological membranes the most versatile and simple possibility to create polymeric membrane nanostructures. Classically, the phase inversion technique involves four essential steps: Preparation of a polymer solution in the desired solvent, the formation of the polymer solution film on a flat support, the immersion of the film in a coagulation bath containing polymer solvents, and membrane conditioning. All phase inversion stages are important for the prepared membrane's nanostructure and have been studied in detail for more than six decades. In this paper, we explored, through an electrochemical technique, the influence of the contact time with the polymer film's environment until the introduction into the coagulation bath. The system chosen for membrane preparation is polysulfone-dimethylformamide-aqueous ethanol solution (PSf-DMF-EW). The obtained nanostructured membranes were characterized morphologically and structurally by scanning electron microscopy (SEM) and thermal analysis (TA), and in terms of process performance through water permeation and bovine serum albumin retention (BSA). The membrane characteristics were correlated with the polymeric film exposure time to the environment until the contact with the coagulation bath, following the diagram of the electrochemical parameters provided by the electrochemical technique.

Multiplex bioassaying of cancer proteins and biomacromolecules: Nanotechnological, structural and technical perspectives.

Since the specific proteins (carbohydrate antigens, ligands and interleukins) get raised up in body tissue or fluids in cancer cases, early detection of them will provide an effective treatment and survival rate. Sensitive and accurate determination of multiple cancer proteins can be engaged in chorus by simultaneous/multiplex detection in the biomedical fields. Bioassaying technology is one of the non-invasive, high-sensitive, and economical methods. Currently, extensive application of nanomaterial (biocompatible polymers, metallic and metal oxide) in bioassays resulted in ultra-high sensitive and selective diagnosis. This review article focuses on types of multiplex bioassays for delicate and specific determination of cancer proteins for diagnostic aims. It also covers two modes of multiplex bioassays as multi labeled bioassays and spatially-separated test zones (multi-electrode mode). In this review, the nanotechnological, structural, and technical perspectives in the multiplex analysis of cancer proteins were discussed. Finally, the use of different types of nanomaterials, polysaccharides, biopolymers and their advantages in signal amplification are discussed.

Eighteen Months Follow-Up with Patient-Centered Outcomes Assessment of Complete Dentures Manufactured Using a Hybrid Nanocomposite and Additive CAD/CAM Protocol.

Abstract: The present study aimed to assess the eighteen month follow-up patient-centered outcomes of a simple and predictable protocol for 3D-printed functional complete dentures manufactured using an improved poly(methyl methacrylate) (PMMA)-nanoTiO2. A detailed morphological and structural characterization of the PMMA-TiO2 nanocomposite, using SEM, EDX, XRD, and AFM, after 3D-printing procedure and post-wearing micro-CT, was also performed. METHODS: A total of 35 fully edentulous patients were enrolled in this prospective study. A 0.4% TiO2-nanoparticle-reinforced PMMA composite with improved mechanical strength, morphologically and structurally characterized, was used according to an additive computer-aided design and computer-aided manufacturing (CAD/CAM) protocol for complete denture fabrication. The protocol proposed involved a three-step appointment process. Before denture insertion, 1 week, 12 month, and 18-month follow up patients were evaluated via the Visual Analogue Scale (VAS, 0-10) and Oral Health Impact Profile for Edentulous Patients (OHIP-EDENT), with a higher score meaning poor quality of life. RESULTS: A total of 45 complete denture sets were inserted. OHIP-EDENT scored significantly better after 18 months of denture wearing, 20.43 (±4.42) compared to 52.57 (±8.16) before treatment; mean VAS was improved for all parameters assessed. CONCLUSIONS: Within the limitations of this study, we can state that the proposed workflow with the improved material used is a viable treatment option for patients diagnosed with complete edentulism.

Added value recyclability of glass fiber waste as photo-oxidation catalyst for toxic cytostatic micropollutants.

There is an increased interest in recycling valuable waste materials for usage in procedures with high added values. Silica microparticles are involved in the processes of catalysis, separation, immobilization of complexants, biologically active compounds, and different nanospecies, responding to restrictive requirements for selectivity of various chemical and biochemical processes. This paper presents the surface modification of accessible and dimensionally controlled recycled silica microfiber with titanium dioxide. Strong base species in organic solvents: methoxide, ethoxide, propoxide, and potassium butoxide in corresponding alcohol, activated the glass microfibres with 12-13 µm diameter. In the photo-oxidation process of a toxic micro-pollutant, cyclophosphamide, the new composite material successfully proved photocatalytic effectiveness. The present work fulfills simultaneously two specific objectives related to the efforts directed towards a sustainable environment and circular economy: recycling of optical glass microfibers resulted as waste from the industry, and their usage for the photo-oxidation of highly toxic emerging micro-pollutants.

Electrochemiluminescence methods using CdS quantum dots in aptamer-based thrombin biosensors: a comparative study.

The detection of thrombin by using CdS nanocrystals (CdS NCs), gold nanoparticles (AuNPs) and luminol is investigated in this work. Thrombin is detected by three methods. One is called the quenching method. It is based on the quenching effect of AuNPs on the yellow fluorescence of CdS NCs (with excitation/emission wavelengths of 355/550 nm) when placed adjacent to CdS NCs. The second method (called amplification method) is based on an amplification mechanism in which the plasmonics on the AuNPs enhance the emission of CdS NCs through distance related Förster resonance energy transfer (FRET). The third method is ratiometric and based on the emission by two luminophores, viz. CdS NCs and luminol. In this method, by increasing the concentration of thrombin, the intensity of CdS NCs decreases, while that of luminol increases. The results showed that ratiometric method was most sensitive (with an LOD of 500 fg.mL-1), followed by the amplification method (6.5 pg.mL-1) and the quenching method (92 pg.mL-1). Hence, the latter is less useful. Graphical abstract Schematic representation of three different methods (quenching, amplification and ratiometric) were applied for detection of thrombin via aptasensor. The CdS nanocrystals, streptavidin (Str) coated AuNPs and also Str-luminol coated AuNPs were used for the construction steps of the electrochemiluminescence (ECL)-based biosensor.

Recent progress in nanomaterial-based electrochemical biosensors for pathogenic bacteria.

This review (with 118 refs.) discusses the progress made in electroanalytical methods based on the use of organic and inorganic nanomaterials for the determination of bacteria, specifically of E. coli, Salmonella, Staphylococcus, Mycobacterium, Listeria and Klebsiella species. We also discuss advantages and limitations of electrochemical methods. Strategies based on the use of aptamers, DNA and antibodies are covered. Following an introduction into electrochemical biosensing, a first large section covers methods for pathogen detection using metal nanoparticles, with subsections on silver nanoparticles, gold nanoparticles, magnetic nanoparticles and carbon-based nanomaterials. A second large section covers methods based on the use of organic nanocomposites, graphene and its derivatives. Other nanoparticles are treated in a final section. Several tables are presented that give an overview on the wealth of methods and materials. A concluding section summarizes the current status, addresses challenges, and gives an outlook on potential future trends. Graphical abstract This review demonstrates the progress made in electroanalytical methods based on the use of organic and inorganic nanomaterials for the detection and determination of pathogenic bacteria. We also discuss advantages and limitations of electrochemical methods. Strategies based on the use of aptamers, DNA and antibodies are covered.

Non-Resorbable Nanocomposite Membranes for Guided Bone Regeneration Based On Polysulfone-Quartz Fiber Grafted with Nano-TiO2.

The polymer-inorganic nanoparticles composite membranes are the latest solutions for multiple physicochemical resistance and selectivity requirements of membrane processes. This paper presents the production of polysulfone-silica microfiber grafted with titanium dioxide nanoparticles (PSf-SiO2-TiO2) composite membranes. Silica microfiber of length 150-200 µm and diameter 12-15 µm were grafted with titanium dioxide nanoparticles, which aggregated as microspheres of 1-3 µm, applying the sol-gel method. The SiO2 microfibers grafted with nano-TiO2 were used to prepare 12% polysulfone-based nanocomposite membranes in N-methyl pyrrolidone through the inversion phase method by evaporation. The obtained nanocomposite membranes, PSf-SiO2-TiO2, have flux characteristics, retention, mechanical characteristics, and chemical oxidation resistance superior to both the polysulfone integral polymer membranes and the PSf-SiO2 composite membranes. The antimicrobial tests highlighted the inhibitory effect of the PSf-SiO2-TiO2 composite membranes on five Gram (-) microorganisms and did not allow the proliferation of Candida albicans strain, proving that they are suitable for usage in the oral environment. The designed membrane met the required characteristics for application as a functional barrier in guided bone regeneration.

New sensor based on membranes with magnetic nano-inclusions for early diagnosis in periodontal disease.

A series of sodium selective membranes with magnetic nano-inclusions using p-tertbutyl calix[4]arene as ionophore and polymeric matrix (polyvinyl chloride) have been developed, and the corresponding sodium selective sensors were obtained for the first time. A linear range was registered between 3.1 × 10-5 and 10-1moldm-3 and near Nernstian electrochemical answer: 55.73mV/decade has been recoreded for PVC (polyvinyl chloride) - based sodium selective sensor, with a response time of 45s. Due to their small dimensions, sensors could be used for measuring ions from the gingival crevicular fluid directly into the peri-odontal pocket, avoiding the difficulties of collecting an appropriate amount of fluid for analysis. Alterations in the inorganic ions level could be evidenced with this new device, assisting the early diagnosis and prevention of periodontal disease.

Green synthesis of silver nanoparticles using Thymbra spicata L. var. spicata (zahter) aqueous leaf extract and evaluation of their morphology-dependent antibacterial and cytotoxic activity.

Silver (Ag) nanoparticles (NPs) were green synthesized at room temperature using different concentrations of the Thymbra spicata L. var. spicata (Zahter) aqueous leaf extracts for the first time. With the synthesis of AgNPs using the leaf extract of Cynara scolymus (Artichoke) and Mentha piperita (Peppermint), the biological activities of the nanoparticles synthesized using leaf extract of three economically significant plants have been studied comparatively. Nanoparticles were characterized by different spectroscopic and microscopic analysis. TEM analysis of the biosynthesized AgNPs revealed that the size and shape of the AgNPs were changed with the plant extract concentration. Biologically synthesized AgNPs from leaf extracts of the three different plants displayed significant differences in antibacterial activity against two different gram-negative and gram-positive bacteria. Also, the results from this study show the shape dependence of the antibacterial and cytotoxic activity of silver nanoparticles synthesized using T. spicata leaf extract. The nanoparticles with different shapes exhibited the strongest antibacterial and cytotoxic activity compared to mostly spherical nanoparticles. Present results clearly indicate that biological activities of silver nanoparticles were affected by nanoparticle shape and the source of the plant extract used in the synthesis.