Cobalt-based metal-organic framework-functionalized graphene oxide modified electrode as a new electrochemical sensing platform for detection of free chlorine in aqueous solution.

This work reports the profit of using a MOF compound for developing a sensitive electrochemical sensor to free chlorine detection in an aqueous solution. Co-MOF and FGO composites were synthesized and combined with the carbon paste (CP) to prepare an efficient electrochemical sensor with high sensing ability. The fabricated Co-MOF and FGO composites were characterized by SEM, EDX, FT-IR, and XRD techniques. Meanwhile, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were utilized to assess the electrochemical performance of the Co-MOF-FGO/CP modified electrode. Under the optimized condition, the amperometric detection showed that the reduction current of free chlorine increased linearly with a coefficient determination of 0.995 during its wide concentration range of 0.1-700 ppm. Also the detection limit (LOD) (S/N = 3) was 0.01 ppm. The selectivity of the sensor was tested with possible interferences, and satisfactory results were obtained. The proposed sensor was successfully used to determine the free chlorine in tap water and swimming pool water real samples. The results suggested that this proposed sensor could pave the way for developing the electrochemical sensor of free chlorine in aqueous media with MOFs.

Applications of capsaicin in food industry: functionality, utilization and stabilization.

As a bioactive component in Capsicum species, capsaicin is a compound of hot chili peppers which is known as the main substance responsible for the spiciness of these fruits. Besides its taste and physiological effects, it exhibits good antioxidant activity in food matrix and antimicrobial activity against foodborne pathogens and viruses. Considering its low stability and bioaccessibility, and also regarding its irritation, the entrapment methods of capsaicin are fully developed. To compensate the limitations of capsaicin, various encapsulation methods have been used so far, including coacervation, emulsion, spray chilling, and liposomal delivery. Capsaicin has been widely used as a flavoring and preservative agent in food formulations and even as an active compound in packaging film and functional foods. This review provides an overview of the techno-functional properties, stabilization procedures, and burgeoning usages of capsaicin in the latest studies of the food sector. So, it may introduce new windows for the application of this compound.

Microbiological quality of hospital-prepared blenderised tube feeding.

BACKGROUND: Contaminated blenderised tube feeding (BTF) causes numerous infections in patients with deficient immune systems. The microbial quality of BTF should be thoroughly monitored to reduce the risks of microbial agents and prevent food safety problems such as food poisoning and food-borne illnesses. The aim of this study was to survey the contamination rate of BTF samples prepared in the teaching hospitals in Mashhad, Iran. METHODS: This study was conducted on 24 samples of BTF prepared in four teaching hospitals in Mashhad city; the samples were collected randomly. Then specific culture media were used for detected and counted Listeria monocytogenes, Salmonella spp., Staphylococcus aureus, Clostridium perfringens, Bacillus cereus, coliforms and Escherichia coli. The final confirmation of the isolates was performed using polymerase chain reaction. RESULTS: The total bacterial count was determined in the BTF samples and compared with the Food and Drug Administration medical food standards; 91.6% of the samples had 5.2 ± 0.1 log CFU/ml microbial bacterial contamination considering the standard range. The mean prevalence of contamination in these samples was measured for coliforms 4.9 ± 0.17 log CFU/ml, B. cereus 3.6 ± 0.16 log CFU/ml, S. aureus 3.7 ± 0.15 log CFU/ml and C. perfringens 4.7 ± 0.08 log CFU/ml (p < 0.05). Moreover, E. coli 11 (45.8%), Salmonella spp. 9 (37.5%) and L. monocytogenes 17 (70.8%) samples were detected. CONCLUSION: Given the high consumption of BTF and the transmission of food contamination to hospitalised patients, it is essential to improve the hygienic conditions at the site of BTF preparation to prevent re-contamination.

Aptamer-modified metal organic frameworks for measurement of food contaminants: a review.

The measurement of food contaminants faces a great challenge owing to the increasing demand for safe food, increasing consumption of fast food, and rapidly changing patterns of human consumption. As different types of contaminants in food products can pose different levels of threat to human health, it is desirable to develop specific and rapid methods for their identification and quantification. During the past few years, metal-organic framework (MOF)-based materials have been extensively explored in the development of food safety sensors. MOFs are porous crystalline materials with tunable composition, dynamic porosity, and facile surface functionalization. The construction of high-performance biosensors for a range of applications (e.g., food safety, environmental monitoring, and biochemical diagnostics) can thus be promoted through the synergistic combination of MOFs with aptamers. Accordingly, this review article delineates recent innovations achieved for the aptamer-functionalized MOFs toward the detection of food contaminants. First, we describe the basic concepts involved in the detection of food contaminants in terms of the advantages and disadvantages of the commonly used analytical methods (e.g., DNA-based methods (PCR/real-time PCR/multiplex PCR/digital PCR) and protein-based methods (enzyme-linked immunosorbent assay/immunochromatography assay/immunosensor/mass spectrometry). Afterward, the progress in aptamer-functionalized MOF biosensors is discussed with respect to the sensing mechanisms (e.g., the role of MOFs as signal probes and carriers for loading signal probes) along with their performance evaluation (e.g., in terms of sensitivity). We finally discuss challenges and opportunities associated with the development of aptamer-functionalized MOFs for the measurement of food contaminants.

An ultrasensitive aptamer-based fluorescent on/off system for trace amount evaluation of Yersinia enterocolitica in food samples.

An innovative aptamer labeled with 5-FAM has been developed with a high affinity for Yersinia enterocolitica (Y. enterocolitica) using graphene oxide (GO) as a quenching platform. The selectivity of the prepared system was evaluated in the presence of common coexisted bacteria like Yersinia pseudotuberculosis, Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella typhimurium. Some experimental factors like pH and stability were investigated. The results showed that in the absence of Y. enterocolitica, aptamer labeled with 5-FAM was bonded with GO, causing fluorescence to be relatively weak. After the addition of Y. enterocolitica, the aptamer is released from the GO surface and binds to the target bacteria, and significantly increases the fluorescence intensity with an excitation wavelength of 410 nm and an emission wavelength of 530 nm. After optimizing all conditions, the system exhibited a wide linear response for Y. enterocolitica in the concentration range 10 to 1.0 × 109 CFU•mL-1 and the limit of detection (LOD) was 3 CFU•mL-1. This system demonstrated that GO-designed aptamers can be successful in detecting Y. enterocolitica in whole-cell forms, making them potentially useful for screening and rapid detection.

Treatment of synthetic textile wastewater containing Acid Red 182 by electro-Peroxone process using RSM.

The Azo dyes are primarily utilized in textile industries. Treatment of textile wastewater because of the presence of recalcitrant dyes using conventional processes is greatly challenging and ineffective. So far, no experimental work has been conducted on the decolorization of Acid Red 182 (AR182) in aqueous media. Hence, in this novel experimental work, the treatment of AR182 from the Azo dyes family was explored using the electro-Peroxone (EP) process. For the optimization of operating factors, including AR182 concentration, pH, applied current, and O3 flowrate in the decolorization of AR182, Central Composite Design (CCD) was utilized. The statistical optimization presented a highly satisfactory determination coefficient value and a satisfactory second-order model. The expected optimum conditions by the experimental design were as the following: AR182 concentration at 483.12 mg.L-1, applied current at 0.627,113 A, pH at 8.18284 and O3 flowrate at 1.13548 L min-1. The current density is directly proportional to dye removal. However, increasing the amount of applied current beyond a critical value has a contradictory impact on dye removal performance. The dye removal performance in both acidic and highly alkaline environments was negligible. Hence, ascertaining the optimum pH value and conduction of the experiment at that point is critical. At optimum points, the decolorization performance in predicted and experimental conditions for AR182 were 99 and 98.5%, respectively. The outcomes of this work clearly substantiated that the EP can be successfully utilized for the decolorization of AR182 in textile wastewater.

Stimuli-Responsive Electrochemical Energy Storage Devices.

Electrochemical energy storage (EES) devices have been swiftly developed in recent years. Stimuli-responsive EES devices that respond to different external stimuli are considered the most advanced EES devices. The stimuli-responsive EES devices enhanced the performance and applications of the EES devices. The capability of the EES devices to respond to the various external stimuli due to produced advanced EES devices that distinguished the best performance and interactions in different situations. The stimuli-responsive EES devices have responsive behavior to different external stimuli including chemical compounds, electricity, photons, mechanical tensions, and temperature. All of these advanced responsiveness behaviors have originated from the functionality and specific structure of the EES devices. The multi-responsive EES devices have been recognized as the next generation of stimuli-responsive EES devices. There are two main steps in developing stimuli-responsive EES devices in the future. The first step is the combination of the economical, environmental, electrochemical, and multi-responsiveness priorities in an EES device. The second step is obtaining some advanced properties such as biocompatibility, flexibility, stretchability, transparency, and wearability in novel stimuli-responsive EES devices. Future studies on stimuli-responsive EES devices will be allocated to merging these significant two steps to improve the performance of the stimuli-responsive EES devices to challenge complicated situations.

Smart Biopolymer-Based Nanocomposite Materials Containing pH-Sensing Colorimetric Indicators for Food Freshness Monitoring.

Nanocomposite biopolymer materials containing colorimetric pH-responsive indicators were prepared from gelatin and chitosan nanofibers. Plant-based extracts from barberry and saffron, which both contained anthocyanins, were used as pH indicators. Incorporation of the anthocyanins into the biopolymer films increased their mechanical, water-barrier, and light-screening properties. Infrared spectroscopy and scanning electron microscopy analysis indicated that a uniform biopolymer matrix was formed, with the anthocyanins distributed evenly throughout them. The anthocyanins in the composite films changed color in response to alterations in pH or ammonia gas levels, which was used to monitor changes in the freshness of packaged fish during storage. The anthocyanins also exhibited antioxidant and antimicrobial activity, which meant that they could also be used to slow down the degradation of the fish. Thus, natural anthocyanins could be used as both freshness indicators and preservatives in biopolymer-based nanocomposite packaging materials. These novel materials may therefore be useful alternatives to synthetic plastics for some food packaging applications, thereby improving the environmental friendliness and sustainability of the food supply.

Energy Harvesting/Storage and Environmental Remediation via Hot Drinks Wastes.

Providing energy and materials are considered one most important issue in the world. Produce and storage energy and also, prepare chemical substances from disposable biomass materials have been widely developed in recent decades to decrease environmental pollutions and production costs. The waste of hot drinks including coffee wastes and tea wastes have considerable potentials to provide energy and different chemical substances. Also, hazardous materials (especially aqueous ions) can be absorbed via hot drinks wastes to protect the environment against perilous pollutants. The low-cost and benign hot drinks wastes including tea wastes and coffee grounds and also the pyrolyzed of them as the hot drinks waste biochar materials have been widely used to produce and store green energies and also, absorb hazardous materials. Production and storage energy and environmental remediation in these sustainable procedures not only reduce the cost of energy but also protect the environment.

Corn-based Electrochemical Energy Storage Devices.

The attention to renewable materials is amazingly increased in recent years to decrease environmental pollutions. Zea mays (corn) is one of the most produced plants by humans to provide food and energy. Hence, corn wastes as abundant and low-cost biomass are easily found throughout the world. Tremendous efforts have been accomplished in recent years to fabricate electrochemical energy storage devices (EES) from renewable biomass materials because of increasing attention to the environment. All main parts of EES devices include electrodes, binder, electrolyte, and membrane (separator) can be produced via corn waste biochar and corn derivatives. The low-cost corn-based EES devices not only decrease environmental pollution but also have significant electrochemical properties include specific capacitance and electrochemical durability. This review investigates state-of-the-art development in the corn-based EES devices.

Electrochemical Energy Storage Electrodes via Citrus Fruits Derived Carbon: A Minireview.

This review investigates the synthesis and electrochemical performance of the electrode of the electrochemical energy storage (EES) devices obtained from peels and scraps of the citrus fruits. The EES devices include batteries, supercapacitors, and hybrid systems that have considerable value and various applications. The electrode is considered as the most important part of all EES devices. Tremendous efforts have been done to enhance the electrochemical energy storage electrode (EESE). The citrus fruits abundance leads to a decrease in their price and makes possible to use them as ingredients to fabricate EESE. Also, the electrochemical analyses determined that citrus fruits have considerable potential to use as the EESE. Using citrus fruits peels and scraps as biomass substances to prepare EESE leads to the electrodes which have low cost, environmentally friendly and appropriate electrochemical applications.

Graphene and Graphene/Polymer Composites as the Most Efficient Protective Coatings for Steel, Aluminum and Copper in Corrosive Media: A Review of Recent Studies.

The metal corrosion is considered as a severe threat to the national economy and industry structure, capable of triggering significant economic losses and severe damages, involving innumerable fields in daily life and industries. This review provides an overview of the physioelectrochemical studies on anticorrosive properties of various types of graphene coatings. Required electrochemical techniques for the investigation of anticorrosive efficiency, various types of graphene-based materials coatings along with different routes to provide desirable coated layers are discussed in detail. After all, we intend to show that the modified graphene nanosheets can be regarded as effective protective layers against metal corrosion not only because of their extraordinary mechanical strength and toughness, which can be reached with a vastly thin layer, but also for their high transparency, cost-efficiency and stability.

Increased glucose metabolism in Arid5b-/- skeletal muscle is associated with the down-regulation of TBC1 domain family member 1 (TBC1D1).

BACKGROUND: Skeletal muscle has an important role in regulating whole-body energy homeostasis, and energy production depends on the efficient function of mitochondria. We demonstrated previously that AT-rich interactive domain 5b (Arid5b) knockout (Arid5b-/-) mice were lean and resistant to high-fat diet (HFD)-induced obesity. While a potential role of Arid5b in energy metabolism has been suggested in adipocytes and hepatocytes, the role of Arid5b in skeletal muscle metabolism has not been studied. Therefore, we investigated whether energy metabolism is altered in Arid5b-/- skeletal muscle. RESULTS: Arid5b-/- skeletal muscles showed increased basal glucose uptake, glycogen content, glucose oxidation and ATP content. Additionally, glucose clearance and oxygen consumption were upregulated in Arid5b-/- mice. The expression of glucose transporter 1 (GLUT1) and 4 (GLUT4) in the gastrocnemius (GC) muscle remained unchanged. Intriguingly, the expression of TBC domain family member 1 (TBC1D1), which negatively regulates GLUT4 translocation to the plasma membrane, was suppressed in Arid5b-/- skeletal muscle. Coimmunofluorescence staining of the GC muscle sections for GLUT4 and dystrophin revealed increased GLUT4 localization at the plasma membrane in Arid5b-/- muscle. CONCLUSIONS: The current study showed that the knockout of Arid5b enhanced glucose metabolism through the downregulation of TBC1D1 and increased GLUT4 membrane translocation in skeletal muscle.

Rainbow trout fillet biopreservation by edible chitosan-based coating containing egg yolk antibody (IgY) and lycopene.

The aim of the study was to investigate the effect of the extracted egg yolk antibody along with lycopene on the chemical quality of the rainbow trout fillet during 16 days of refrigeration storage. Chickens were immunized against Pseudomonas fluorescens (P. fluorescens), Shewanella putrefaciens (S. putrefaciens) and total spoilage bacteria and their eggs were collected for the isolation of egg yolk antibodies. Then fish fillets were immersed in chitosan-based coating solutions, containing lycopene and extracted antibodies, and analyzed for lipid oxidation changes (peroxide, thiobarbituric acid, free fatty acid and fatty acid profile), physico-chemical properties (pH and water holding capacity), and sensory evaluation, during 16 days of refrigeration storage. Results showed that chitosan solutions with lycopene or IgY could significantly (p < 0.05) increase the oxidative stability of lipids in fish fillets; although, combinational use of lycopene and IgY showed a higher effect on delaying the rate of lipid oxidation. Significant differences were also observed between treatments contained combination of chitosan, antibody and lycopene with the control group, regarding pH and WHC. Saturated fatty acids increased in all treatments, although the changes in the treatments containing lycopene and antibody were significantly (p < 0.05) lower than the control group. Hence the addition of egg yolk antibody and lycopene in coating solution are good bio-preservatives for seafood products as it improves sensory attributes and prevents lipid oxidation.

Red beet extract usage in gelatin/gellan based gummy candy formulation introducing Salix aegyptiaca distillate as a flavouring agent.

Nowadays, the functionalization of food products using natural health-promoting additives is of great interest. Betalains are the natural pigments of red beets and are known for their health-promoting characteristics. The aim of this study was to evaluate gummy candies formulated with red beet extract (0.1 or 0.3%) as the coloring agent, Salix aegyptiaca distillate as the flavoring agent, and gellan gum (0.5 or 1.5%) as the gelling co-agent. The prepared gummy candy samples were assessed via texture profile analysis, DPPH assay, sensory evaluation, and color analysis. The results revealed that hardness (~ 60 N) improved and gumminess (~ 15 N) decreased with an increment in gellan gum content in the gummy candy formulation. Statistical analysis indicated that by addition of red beet extract, the radical scavenging capacity of the samples increased (50%) significantly (p < 0.05). Furthermore, gellan gum usage lead to the generation of a glossy red color and enhanced the lightness of the samples in comparison with gelatin-based gummy candies. About sensory evaluation, the panelists confirmed that usage of Salix aegyptiaca improved the sensory characteristics of the gummy candy (overall acceptance from 7.4 to 8.2; out of 9). Our findings suggest that gellan gum (as a highly transparent, acid-resistant, gel-forming gum), red beet extract (as an acid-stabilized natural color), and Salix aegyptiaca distillate have immense potential in the food industry for use as structuring, coloring, and flavoring agents, respectively.

Electrochemical Pseudocapacitors Based on Ternary Nanocomposite of Conductive Polymer/Graphene/Metal Oxide: An Introduction and Review to it in Recent Studies.

This review gives an overview of the synthesis, surface and electrochemical investigations over ternary nanocomposite of conductive polymers in the development of new supercapacitors. They utilize both Faradaic and non-Faradaic procedures to store charge, leading to higher specific capacitance and energy density, higher cell voltage, longer life cycle and moderated power density. Owing to a unique combination of features such as superb electrical conductivity, corrosion resistance in aqueous electrolytes, highly modifiable nanostructures, long cycle life and the large theoretical specific-surface area, the use of ternary nanocomposites as a supercapacitor electrode material has become the focus of a significant amount of current scientific researches in the field of energy storage devices. In these nanocomposites, graphene not only can be utilized to provide a substrate for growing nanostructured polymers in a polymer-carbon nanocomposite structure in order to overcome the insulating nature of conductive polymers at dedoped states, but also is capable of providing a platform for the decoration of metal oxide nanoparticles to avoid their agglomeration. In this regard, synthesis, characterization and performance of different ternary nanocomposites of conductive polymer/graphene/metal oxide are discussed in detail. These remarkable results demonstrate the exciting commercial potential for high performance, environmentally friendly and low-cost electrical energy storage devices based on ternary nanocomposite of conductive polymer/graphene/metal oxide.

Microbial gums: introducing a novel functional component of edible coatings and packaging.

In recent years, the accumulation of synthetic plastics has led to the development of a serious environmental problem. Nowadays, biodegradable films and coatings have been identified as a new approach to solve this problem by preparing renewable, abundant, low-cost materials. Gums are considered a large group of polysaccharides and polysaccharide derivatives that can easily form viscous solutions at low concentrations. Gums are mainly soluble in water and are composed of sugars like glucose, fructose, and mannose. These compounds are categorized into three groups: plant-origin gums, seaweed-based gums, and microbial gums. Microbial gums are listed as generally recognized as safe (GRAS) by the Food and Drug Administration and have a broad range of physicochemical properties suitable for various pharmacy, medicine, and food applications. In the food industry, they can be used as gelling, viscous, stabilizing, and thickening agents. Among the various materials that can potentially improve the properties of biodegradable packaging films, microbial gums such as gellan, xanthan, pullulan, bacterial cellulose, and curdlan have been the subject of numerous studies. These gums can be extruded into films and coatings with considerable barrier properties against the transport of moisture and oxygen. Microbial gums, due to their microbiological stability, adhesion, cohesion, wettability, solubility, transparency, and mechanical properties, can be used as edible films or coatings. Also, these gums can be applied in combination with bioactive compounds that induce the shelf-life extension of highly perishable products. This review focuses on the properties of films and coatings consisting of xanthan, curdlan, pullulan, gellan, and bacterial cellulose.

Extraction of specific egg yolk antibodies and application in chitosan coating: effect on microbial and sensory properties of rainbow trout fillet during chilled storage.

BACKGROUND: This study investigated the effect of chitosan coating enriched with extracted egg yolk antibodies on microbial and sensory quality of rainbow trout fillet during refrigeration (4 ± 1 °C). Firstly, bacterial antigen suspensions (total psychrophilic bacteria, Pseudomonas fluorescens and Shewanella putrefaciens) were injected into the breast muscles of chickens. Eggs of immunized chickens were then collected to isolate immunoglobulin from egg yolks (IgY). Fresh fish fillets were coated by chitosan solution containing different types of IgY separately, at two concentrations (60 and 90 mg mL-1 ), refrigerated for 16 days and analysed for total viable count, psychrotrophic, Pseudomonas spp., P. fluorescens and S. putrefaciens count as well as sensorial properties. RESULTS: The tested microbial values increased in all samples during the storage period; however, CH + IgY treated samples could significantly retard microbial growth compared to control. The shelf life of CH + IgY-P samples was extended for about 4 days, while it was extended for about 8 days in CH + IgY-S and CH + IgY-T samples, when they were compared to control (p < 0.05). Higher scores for sensory attributes were also observed in CH + IgY treated samples, especially in CH + IgY-S samples until the end of storage period. CONCLUSIONS: Accordingly, use of chitosan coating containing IgY increases the microbial and sensory quality of fish flesh at 4 °C. Therefore, given the consumer interest in natural additives, chitosan coating containing IgY can be a promising candidate. © 2018 Society of Chemical Industry.

Nanoparticles and their antimicrobial properties against pathogens including bacteria, fungi, parasites and viruses.

In recent year, propagation and resistance of pathogenic microorganisms (bacteria, fungi and virals) to common antimicrobial agents has led to serious health and food problems. Today, nanotechnology science and nanoparticles (NPs) have been identified as a new approach to deal with this problem because of their inherent antimicrobial activity. Several studies have reported that, NPs (metal and metal oxide) are considered as a group of materials that can be studied due to their antimicrobial properties. In this review, we investigated recent studies regarding the antimicrobial activity of NPs with their mechanism of action. Many research has proved that particle size is a significant factor which indicates the antimicrobial effectiveness of NPs. The use of NPs as antimicrobial component especially in the food additives and medical application can be one of the new and considerable strategies for overcoming pathogenic microorganisms. Nevertheless, more studies must be conducted to minimize the possible toxicity of NPs in order to use as suitable alternatives for disinfectants and antibacterial agents in food applications.

Recent Progress in the Development of Conducting Polymer-Based Nanocomposites for Electrochemical Biosensors Applications: A Mini-Review.

Among various immobilizing materials, conductive polymer-based nanocomposites have been widely applied to fabricate the biosensors, because of their outstanding properties such as excellent electrocatalytic activity, high conductivity, and strong adsorptive ability compared to conventional conductive polymers. Electrochemical biosensors have played a significant role in delivering the diagnostic information and therapy monitoring in a rapid, simple, and low cost portable device. This paper reviews the recent developments in conductive polymer-based nanocomposites and their applications in electrochemical biosensors. The article starts with a general and concise comparison between the properties of conducting polymers and conducting polymer nanocomposites. Next, the current applications of conductive polymer-based nanocomposites of some important conducting polymers such as PANI, PPy, and PEDOT in enzymatic and nonenzymatic electrochemical biosensors are overviewed. This review article covers an 8-year period beginning in 2010.