Cholesterol biosensors: A review Narwal, Vinay; Deswal, Ritu; Batra, Bhawna ...
Steroids,
March 2019, 2019-03-00, 20190301, Letnik:
143
Journal Article
Recenzirano
•Serum cholesterol level plays important role in the diagnosis and treatment of various diseases e.g. hypothyroidism, nephrotic syndrome, diabetes and liver diseases.•Cholesterol level upto 200 mg/dL ...(healthy person), 200–239 mg/dL (borderline high).•Present review summarizes the principle of various biosensing methods for determination of cholesterol.
Cholesterol is the most important sterol synthesized by most of the human cells majorly in the liver. It is a necessary constituent of cell membranes, it acts as a precursor for the synthesis of steroid hormones, vitamin D, and bile acids. Cholesterol is transported in plasma primarily in the form of low-density lipoproteins (LDL), the principal route for its removal from tissues to the liver is in high-density lipoproteins (HDL), followed by excretion in the bile. Cholesterol level is less than 200 mg/dL in healthy persons. 200 and 239 mg/dL is considered borderline high and 240 mg/dL and above is considered a biomarker for cardiovascular diseases, heart attack, strokes, peripheral arterial disease, type 2 diabetes and high blood pressure. Several methods are available for detection of cholesterol, among them, most are burdensome, time-consuming, require sample pre-treatment, high-cost instrumental set-up, and experienced personnel to operate. Biosensing approach overcomes these disadvantages, as these are highly specific, fast, easy, cost-effective, and highly sensitive. The review describes the various cholesterol biosensors. Cholesterol biosensors work ideally within 1 to 300 s, in pH range, 7.0–8.6, temperature 25–37 °C and cholesterol concentration range, 0.000025–700 mM, the detection limits being in the range, 0.000002–4 mM, with working potential −0.05 to 0.65 V. These biosensors measured cholesterol level in fruit juices, beverages, sera and urine samples and reused up to 200 times over a period of 15 to 50 days, while stored dry at 4 °C (Table 1). Future perspective for further improvement and commercialization of cholesterol biosensors are discussed.
Gravitational waves have been detected from a binary neutron star merger event, GW170817. The detection of electromagnetic radiation from the same source has shown that the merger occurred in the ...outskirts of the galaxy NGC 4993, at a distance of 40 megaparsecs from Earth. We report the detection of a counterpart radio source that appears 16 days after the event, allowing us to diagnose the energetics and environment of the merger. The observed radio emission can be explained by either a collimated ultrarelativistic jet, viewed off-axis, or a cocoon of mildly relativistic ejecta. Within 100 days of the merger, the radio light curves will enable observers to distinguish between these models, and the angular velocity and geometry of the debris will be directly measurable by very long baseline interferometry.
•Deficiency of folic acid leads to diseases e.g. neural tube defects in newborn.•The normal levels of folic acid in human blood serum should be 2–15 ng/mL.•Review summarizes the principle of various ...biosensing methods for folic acid.
Folic acid (FA) also known as (N-p-{(2-amino-4-hydroxy-6-pteridinyl) methyl amino} benzoyl-l-glutamic acid), is a water soluble vitamin found in plants and animals. The deficiency of FA leads to an increased risk of various diseases like neural tube defects in newborn, cardiovascular disease, cancer, Alzheimer’s disease and megaloblastic anemia. The normal levels of FA in human blood serum should fall in the range between 2 and 15 ng/mL. Present review article discusses the classification, principles, advantages and disadvantages of FA biosensing methods. FA biosensors operate within 3–300 s, in pH range, 1.8–7.8, concentration range 8.71 × 10−9 μM for FA. The FA biosensors displayed detection limits (LOD) between 1.6 × 10−11 to 0.091 μM and with working potential −0.88 to 4.5 V. These biosensors measured FA level in various biological and pharmaceuticals samples.
•Antibiotic-resistant urinary tract infections caused mainly by E. coli have accelerated on a global scale.•Combined antimicrobial therapies in the form of phages/ phage cocktails and antibiotics are ...being studied to combat drug-resistant uropathogens.•Four different lytic phages specific for uropathogenic E. coli were isolated and the effects of phage cocktail on uropathogenic E. coli was examined.•Synergistic effects of the phage cocktail with antibiotics showed phage antibiotic synergism by lowering the MIC values of antibiotics.
Infections related to antibiotic resistant bacteria are accelerating on a global scale, and hence to encounter this problem in case of urinary tract infections; bacteriophages were isolated for biocontrol of multi-drug resistant (MDR) uropathogenic Escherichia coli (UPECs) isolates. Four lytic phages were purified, characterized, and evaluated for their effectiveness in the form of cocktail and in synergy with antibiotics. Morphological features and other life cycle specifications of phages revealed that two phages Escherichia phage FS11 and Escherichia phage FS17 belonged to Myoviridae and the other two phages Escherichia phage PS8 and Escherichia phage PS6 belonged to Siphoviridae family of order Caudovirales. One step growth curve analysis demonstrated that phage FS11 and phage FS17 had latent time of 24 min and 26 min, and a burst size of ~121 and 98 phage particles/ cell respectively; while for phage PS8 and phage PS6, the latent time was 42 min and 35 min, and the burst size was 87 and 78 particles/ cell, respectively; depicting the lytic nature of phages. The use of all four phages together in the form of a cocktail resulted into a considerable enhancement in the lytic ability; the phage cocktail lysed 86.7% of the clinical isolates, compared to lysis in the range of 50%-66% by individual phages. Studies on in vitro evaluation of phage-antibiotic combinations revealed synergism between antibiotics and the phage cocktail (phage PS6 and phage FS17), wherein the phage cocktail was observed to efficiently inhibit the strains in the presence of sub-lethal doses of antibiotics. The study thus concludes that the use of multiple phages and phage-antibiotic combinations could prove beneficial in the era of rapidly increasing drug-resistant strains.
•Antibiotics are used extensively in agriculture, livestock and in animal husbandry.•In agriculture, these are used to increase crop productivity; in animal husbandry and livestock to treat sick ...animals and as growth promoters in animal feed at controlled concentrations.•Bacteria are able to modify their genes under stress conditions by different mechanisms, and the resistance genes are cycled among agricultural soils and other different ecosystems through nutrient cycling.•A number of significant molecular strategies have been proposed to reduce the occurrence of antibiotic resistance in bacterial genomes .
Antibiotic resistance is a massive problem rising constantly and spreading rapidly since the past decade. The major underlying mechanism responsible for this problem is an overuse or severe misuse of antibiotics. Regardless of this emerging global threat, antibiotics are still being widely used, not only for treatment of human infections, but also to a great extent in agriculture, livestock and animal husbandry. If the current scenario persists, we might enter into a post-antibiotic era where drugs might not be able to treat even the simplest of infections. This review discusses the current status of antibiotic utilization and molecular basis of antibiotic resistance mechanisms acquired by bacteria, along with the modes of transmittance of the resultant resistant genes into human pathogens through their cycling among different ecosystems. The main focus of the article is to provide an insight into the different molecular and other strategies currently being studied worldwide for their use as an alternate to antibiotics with an overall aim to overcome or minimize the global problem of antibiotic resistance.
The application of membrane technology to remove pollutant dyes in industrial wastewater is a significant development today. The modification of membranes to improve their properties has been shown ...to improve the permeation flux and removal efficiency of the membrane. Therefore, in this work, graphene oxide nanoparticles (GO-NPs) were used to modify the polyethersulfone (PES) membrane and prepare mixed matrix membranes (MMMs). This research is dedicated to using two types of very toxic dyes (Acid Black and Rose Bengal) to study the effect of GO on PES performance. The performance and antifouling properties of the new modified membrane were studied using the following: FTIR, SEM, AFM, water permeation flux, dye removal and fouling, and by investigating the influence of GO-NPs on the structure. After adding 0.5 wt% of GO, the contact angle was the lowest (39.21°) and the permeable flux of the membrane was the highest. The performance of the ultrafiltration (UF) membrane displayed a rejection rate higher than 99% for both dyes. The membranes showed the highest antifouling property at a GO concentration of 0.5 wt%. The long-term operation of the membrane fabricated from 0.5 wt% GO using two dyes improved greatly over 26 d from 14 d for the control membrane, therefore higher flux can be preserved.
Background. Candida auris, a multidrug-resistant yeast that causes invasive infections, was first described in 2009 in Japan and has since been reported from several countries. Methods. To understand ...the global emergence and epidemiology of C. auris, we obtained isolates from 54 patients with C. auris infection from Pakistan, India, South Africa, and Venezuela during 2012–2015 and the type specimen from Japan. Patient information was available for 41 of the isolates. We conducted antifungal susceptibility testing and whole-genome sequencing (WGS). Results. Available clinical information revealed that 41% of patients had diabetes mellitus, 51% had undergone recent surgery, 73% had a central venous catheter, and 41% were receiving systemic antifungal therapy when C. auris was isolated. The median time from admission to infection was 19 days (interquartile range, 9–36 days), 61% of patients had bloodstream infection, and 59% died. Using stringent break points, 93% of isolates were resistant to fluconazole, 35% to amphotericin B, and 7% to echinocandins; 41% were resistant to 2 antifungal classes and 4% were resistant to 3 classes. WGS demonstrated that isolates were grouped into unique clades by geographic region. Clades were separated by thousands of single-nucleotide polymorphisms, but within each clade isolates were clonal. Different mutations in ERG11 were associated with azole resistance in each geographic clade. Conclusions. C. auris is an emerging healthcare-associated pathogen associated with high mortality. Treatment options are limited, due to antifungal resistance. WGS analysis suggests nearly simultaneous, and recent, independent emergence of different clonal populations on 3 continents. Risk factors and transmission mechanisms need to be elucidated to guide control measures.
A method is described for the construction of a highly sensitive electrochemical biosensor for the detection of bilirubin. The sensor is based on covalent immobilization of bilirubin oxidase (BOx) ...onto zirconia coated silica nanoparticles (SiO2@ZrONPs)/chitosan (CHIT) composite electrodeposited onto Au electrode. The enzyme electrode was characterized by scanning electron microscopy (SEM), Fourier transform infra-red spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The biosensor showed optimum response within 2s at pH 8.5 (0.1M Tris–HCl) and 35°C, when operated at 20mVs−1. The biosensor exhibited excellent sensitivity (detection limit as 0.1nM), fast response time and wider linear range (from 0.02 to 250μM). Analytical recovery of added bilirubin was 95.56–97.0%. Within batch and between batch coefficients of variation were 3.2% and 3.35% respectively. The enzyme electrode was used 150 times over a period of 120 days, when stored at 4°C. The biosensor measured bilirubin levels in sera of apparently healthy and persons suffering from jaundice, which correlated well with a standard colorimetric method (r=0.99).
► Constructed a BOx/SiO2@ZrONPs/CHIT/Au hybrid film. ► Fabricated an improved amperometric bilirubin biosensor based on this film. ► Biosensor had a detection limit of 0.1nM and linear range of 0.02–250μM. ► Employed for bilirubin determination in different serum samples.
•Different properties of starches from Indian quinoa varieties were characterized.•Starches exhibited similar shapes, A-type crystal, low breakdown and setback.•Starches differed significantly in ...amylose, pasting, rheological and thermal properties.•Starches showed unique visco-elastic behaviour (High G'), may be used as thickener.•May be used in biodegradable films and in value added products (noodles).
In this study starches isolated from Indian quinoa varieties were examined for physicochemical, morphological, thermal and rheological properties. Among isolated starches V1 showed higher starch yield and lower purity (48.45% and 98.32%) than V2 (41.28 and 98.53%). The amylose content was higher for V1 (12.10%) than V2 (9.46%). Swelling powers and solubility of the starches increased with increasing temperature. Peak viscosity (386.4 RVU) was higher for V1. In contrast V2 showed higher pasting temperature (72.85°C). Low setback viscosity of the starches suggests that they can be profitably used in frozen and refrigerated foods. Starch granules from both varieties were irregular, angular and polygonal in shape. The starch granule size obtained by SEM was 1.23μm for V1 and 1.19μm for V2. Both starches showed a typical A-type diffractrometric pattern with varying crystallinity. Further V1 showed lower transition temperatures (To, Tp and Tc) than V2. FTIR spectroscopy showed higher intensity and broader shape of V2 at OH stretch which can be due to its higher crystallinity. Increased interest is shown in quinoa starch because of its unique microcrystalline granules. Higher yield and purity values suggest that both varieties can be exploited for commercial starch utilization.
The aim of this study was to investigate the effect of Nigella sativa and thymoquinone (TQ) on oxidative stress, cyclooxygenase-2 (COX-2), and intracellular adhesion molecule-1 mRNA expression in the ...pancreas of streptozotocin (STZ)-induced diabetic rats as a model of type 1 diabetes.
Five experimental groups including control group, STZ-induced diabetic group, aqueous extract diabetic treated group, oil diabetic treated group, and TQ diabetic treated group were used to obtain the pancreatic tissue samples and serum for investigation.
A significant increase in COX-2 mRNA expression was detected in STZ-induced diabetic group after 10 days of diabetes induction indicating an important role of the enzyme COX-2 in the inflammation accompanying STZ diabetes in contrast to that detected for intracellular adhesion molecule-1. Treatment of STZ diabetic rats with N. sativa aqueous extract and TQ significantly suppressed the expression of COX-2 enzyme in the pancreatic tissue. Nigella sativa and TQ treatment also suppressed pancreatic tissue lipid peroxidation malondialdehyde levels and increased the level of superoxide dismutase antioxidant enzyme correlated with the decrease in COX-2 mRNA expression.
Results obtained in this study support a potential role for N. sativa and TQ in ameliorating inflammation during diabetes and preserving β cells.
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