A Bacillus sphaericus Based Biosensor for Monitoring Nickel Ions in Industrial Effluents and Foods

A microbial-based biosensor has been developed based on enzyme inhibition bioassay for monitoring the presence of Ni(II) in real-time samples. The sensing element is immobilized Bacillus sphaericus MTCC 5100 yielding urease enzyme. The transducer is an NH 4 + ion selective electrode in conjunction with a potentiometer. Heavy metals are potentially toxic to human beings. Nickel is associated with causing adverse health effects such as dermatitis and vertigo, in humans. Toxicity is manifested by affecting T-cell system and suppressing the activity of natural killer cells. Nickel finds applications in electroplating, coinage, electrodes, jewellery, alloys. The foods rich in Ni(II) are nuts, beans, oats, and wheat. The range of Ni(II) detection by the developed biosensor is 0.03–0.68 nM (0.002–0.04 ppb) with a response time of 1.5 minutes. For application, the Ni(II) effluent was procured from an electroplating industrial unit and was found to have a concentration of 100.0 ppm Ni(II). In foods, wheat flour sample was acid digested and Ni(II) was specifically complexed in the presence of other cations, and had an Ni(II) concentration of 0.044 ppm. The developed system has a reliability of 91.5% and 90.6%, respectively, for the samples and could possibly replace the existing conventional techniques of analysis

Nanosensor platforms for detection of milk adulterants

Milk is a substrate for adulteration, and it is crucial to identify adulterants, and their quantities in milk products. In order to safeguard consumers from fake products and health risks, authenticity of milk products is in high demand. Analytical tools that are comprehensive, quick, and sensitive are necessary to monitor milk quality and screen for any undesirable substances. The traditional methods for the detection of adulterants in milk products are experiencing more difficulties due to their poor selectivity, sensitivity, and unsuitability for complex matrices. The researchers are paying close attention to nanomaterial based sensing systems, which are seen to be among the most effective alternatives to the traditional approaches. This review focuses on optical and electrochemical nanosensors including mechanisms and performances, in relation to their benefits, drawbacks, and applicability to milk products. It also addresses new developments in the field of nanoemsembles platforms for the rapid detection of adulterants in dairy products. A section of particular interest is the detection of milk authenticity, as it is known that milk from different animal species are intermixed

Functional foods as immunomodulators: Tackling the SARS-CoV-2 related cytokine storm–A review

Coronavirus disease 2019 (COVID-19) caused by the novel coronavirus, SARS-CoV-2 continues to strain the health systems globally. Although various therapeutics are being explored for COVID-19 management, such as antiviral drugs, monoclonal antibodies, immunosuppressant drugs, anticoagulants, and the likes, the continuous evolution of the virus as well as symptoms associated with the disease keep offering challenges in its management, thereby necessitating the involvement of a non-linear approach to tackle the disease. In addition to the direct damage caused by the virus to the host, one peculiar phenomenon that occurs is the self-sabotaging immune response leading to cytokine storm syndrome, which contributes to the severity of the disease and higher mortality rates. The cytokine storm is associated with an unrestricted production of pro-inflammatory cytokines, thereby causing acute respiratory distress and sepsis. Functional foods are known to possess immunomodulatory and anti-inflammatory bioactive compounds that are capable of suppressing proinflammatory cytokines while increasing the levels of anti-inflammatory cytokines, through suppression and activation of signaling pathways. This article reviews the immunomodulatory and anti-inflammatory activities of functional foods via the mechanisms involved therein, and warrant their use in the management of COVID-19, as supportive therapies that complement standard treatment regimens

Fabrication and characterization of a bilayered system enabling sustained release of bioflavonoids derived from mandarin biomass

Food-grade hydrogels, those prepared with Generally Recognized as Safe (GRAS) polymers, are promising delivery systems. In this work, alginate hydrogels were studied for their ability to uphold flavonoids laden poly-lactic-co-glycolic acid (PLGA) nanoparticles, and their subsequent release pattern was observed through in vitro gastrointestinal environments. Flavonoids were derived from mandarin peels, and consisted of polymethoxyflavones, chiefly tangeretin and nobiletin, and flavanones, chiefly naringenin. Incorporating these into nanoparticles prepared from GRAS classified PLGA, hereinafter referred to as flavonoids-PLGA nanoparticles, offered the first layer of protection, which were then embedded into alginate hydrogels, offering the second layer of protection. This bilayered system was developed to ensure guarded passage of the bioactives through the severe gastric environment, which would otherwise lead to presystemic metabolism of the flavonoids, rendering them ineffective. The gels were characterised and a 6.0% alginate hydrogel was considered optimal as it offered a dense network, as confirmed by a field emission scanning electron microscope (FE-SEM) image, and a low porosity, which ensured retention of the nanoparticles. Gel rheology revealed the shear thinning behavior of hydrogels, and high resistance to deformation was observed for 6% hydrogel when subjected to a load of 500N. Subjecting the ensemble to gastrointestinal environments showed a negligible 4.0% release of flavonoids in the first 2 hours of the gastric phase, followed by a sustained release through the next 10 hours in the intestinal environment, as confirmed by mass spectrometry (MS) profiles. Confocal laser scanning microscope (CLSM) images of the hydrogel clearly revealed the pH-responsive swelling and release of the nanoparticles from the hydrogel in the intestinal phase. It is envisaged that these, and other similar findings, would eventually manifest into ‘functional hydrogels’ delivery systems that bear the ability to incorporate nutraceuticals whilst retaining their functionality, as viable products in the near future

L-arginine biosensors: A comprehensive review

Arginine has been considered as the most potent nutraceutics discovered ever, due to its powerful healing property, and it's been known to scientists as the Miracle Molecule. Arginine detection in fermented food products is necessary because, high level of arginine in foods forms ethyl carbamate (EC) during the fermentation process. Therefore, L-arginine detection in fermented food products is very important as a control measure for quality of fermented foods, food supplements and beverages including wine. In clinical analysis arginine detection is important due to their enormous inherent versatility in various metabolic pathways, topmost in the synthesis of Nitric oxide (NO) and tumor growth. A number of methods are being used for arginine detection, but biosensors technique holds prime position due to rapid response, high sensitivity and high specificity. However, there are many problems still to be addressed, including selectivity, real time analysis and interference of urea presence in the sample. In the present review we aim to emphasize the significant role of arginine in human physiology and foods. A small attempt has been made to discuss the various techniques used for development of arginine biosensor and how these techniques affect their performance. The choice of transducers for arginine biosensor ranges from optical, pH sensing, ammonia gas sensing, ammonium ion-selective, conductometric and amperometric electrodes because ammonia is formed as a final product

Polypyrrole based amperometric glucose biosensors

Biosensors have gained immense acceptance in the field of medical diagnostics, besides environmental, food safety and biodefence applications due to its attributes of real-time and rapid response. This synergistic combination of biotechnology and microelectronics comprises a biological recognition element coupled with a compatible transducer device. Diabetes is a disease of major concern since the ratio of world population suffering from it is increasing at an alarming rate and therefore the need for development of accurate and stable glucose biosensors is evident. There are many commercial glucose biosensors available yet some limitations need attention. This review presents a detailed account of the polypyrrole based amperometric glucose biosensors. The polymer polypyrrole is used extensively as a matrix for immobilization of glucose oxidase enzyme owing to its favourable features such as stability under ambient conditions, conductivity that allows it to be used as an electron relay, ability to be polymerized under neutral and aqueous mild conditions, and more. The simple one-step electrodeposition on the electrode surface allows easy entrapment of the enzyme. The review is structured into three categories (a) the first-stage biosensors: which report the studies from the inception of use of polypyrrole in glucose biosensors during which time the role of the polymer and the use of mediators was established. This period saw extensive work by two separate groups of Schuhmann and Koopal who contributed a great deal in understanding the electron transfer pathways in polypyrrole based glucose biosensors, (b) the second-stage biosensors: which highlight the shift of polypyrrole from a conventional matrix to composite matrices with extensive use of mediators focused at improving the selectivity of response, and (c) third-stage biosensors: the remarkable properties of nanoparticles and carbon nanotubes and their outstanding ability to mediate electrontransfers have seen their indispensable use in conjugation with polypyrrole for development of glucose biosensors with improved sensitivity and stability characteristics which is accounted in the review, which thus traces the evolution of polypyrrole from a conventional matrix, to composites and thence to the form of nanotube arrays, with the objective of addressing the vital issue of diabetes management through the development of stable and reliable glucose biosensors

Urea biosensors

A biosensor is an analytical tool that comprises two essential components-an immobilized biocomponent, in intimate contact with a transducer that converts a biological signal into a measurable electrical signal. This review summarizes the studies carried on the development of biosensors for the analysis of urea in different fields of application, the various techniques of immobilization of urease enzyme, the stability and response time characteristics and the transducers used for biosensor development such as pH electrodes, ammonia gas sensing electrodes, ammonium ion-selective electrodes, optical, conductometric and amperometric transducers. Underlying the importance of this study is the fact that urea is toxic above certain concentrations and its continuous real time monitoring in clinical, environmental and food related environments is of utmost interest. The conventional analytical techniques used, although precise, are time consuming and mostly laboratory bound whereas biosensors have the advantages of ease of use, portability and the ability to furnish real time signals