Design and fabrication of La-based perovskites incorporated with functionalized carbon nanofibers for the electrochemical detection of roxarsone in water and food samples.

The pentavalent arsenic compound roxarsone (RSN) is used as a feed additive in poultry for rapid growth, eventually ending up in poultry litter. Poultry litter contains chicken manure, which plays a vital role as an affordable fertilizer by providing rich nutrients to agricultural land. Consequently, the extensive use of poultry droppings serves as a conduit for the spread of toxic forms of arsenic in the soil and surface water. RSN can be easily oxidized to release highly carcinogenic As(III) and As(IV) species. Thus, investigations were conducted for the sensitive detection of RSN electrochemically by developing a sensor material based on lanthanum manganese oxide (LMO) and functionalized carbon nanofibers (f-CNFs). The successfully synthesised LMO/f-CNF composite was confirmed by chemical, compositional, and morphological studies. The electrochemical activity of the prepared composite material was examined using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The obtained results confirmed that LMO/f-CNF showed enhanced electrocatalytic activity and improved current response with a good linear range (0.01-0.78 µM and 2.08-497 µM, respectively), exhibiting a low limit of detection (LOD) of 0.004 µM with a high sensitivity of 13.24 µA µM-1 cm-2 towards the detection of RSN. The noteworthy features of LMO/f-CNF composite with its superior electrochemical performance enabled reliable reproducibility, exceptional stability and reliable practical application in the analysis of tap water and food sample, affording a recovery range of 86.1-98.87%.

N-Hydroxysuccinamide functionalized iron oxide nanoparticles conjugated with 5-flurouracil for hyperthermic therapy of malignant liver cancer cells by DNA repair disruption.

Magnetized iron oxide nanoparticles are ideal materials for biological and biomedical applications due to their biocompatibility, super paramagnetic behavior, surface capability, and chemical stability. This research article is narrating the overview of methodologies of preparation, functionalization, characterization and applications of Fe3O4 nanoparticles. Super paramagnetic nanoparticles are studied for their hyperthermia properties. The proposed mechanism behind the hyperthermia was damaging the proteins responsible for DNA repair thereby, directly accelerating the DNA damages on cancer cells by increasing the temperature in the vicinity of the cancer cells. In this study, super paramagnetic iron oxide (Fe3O4) nanoparticles (SPIONs) and anti-cancer drug, 5-fluorouracil, functionalized with N-Hydroxysuccinimide organic molecules. A specific absorption rate at 351 nm can be achieved using UV analysis. The magnetic Fe3O4 nanoparticles had a cubic crystalline structure. FE-SEM(field emission scanning Electron microscopy) with EDAX(energy dispersive X-ray analysis) analysis shows that the size of the SPION was about 30-100 nm range and the percentage of chemical compositions was higher in the order of Fe, O, C. for particle size analysis, the SPION were positively charged derived at +9.9 mV and its conductivity is measured at 0.826 mS/cm. In-vitro anti-cancerous activity analysis in Hep-G2 cells (liver cancer cells) shows that the 5-fluorouracil functionalized SPIONs have higher inhibition rate than the bare Fe3O4 nanoparticles. The Fe3O4 nanoparticles were studied for their hyperthermic abilities at two different frequencies such as 3.05 × 106 kAm-1s-1 and 4.58 × 106 kAm-1s-1.The bare Fe3O4 at low magnetic field, 10 mg was required to raise the temperature above 42°- 45 °C and at high magnetic field, 6 mg was enough to raise the same temperature. The 5-fluorouracil functionalized Fe3O4 shows that at low magnetic field, 6 mg is required to raise the hyperthermia temperature and at high magnetic field, 3 mg is required to raise the temperature above 42°- 45 °C. the rate of heating and the temperature achieved with time can be tuned with concentrations as well as magnetic component present in the Fe3O4 nanoparticles. Beyond this concentration, the rate of cell death was observed to increase. The saturation and low residual magnetization were revealed by the magnetization analysis, making them well suited for clinical applications.

A Brief Review of Graphene-Based Biosensors Developed for Rapid Detection of COVID-19 Biomarkers.

The prevalence of mutated species of COVID-19 antigens has provided a strong impetus for identifying a cost-effective, rapid and facile strategy for identifying the viral loads in public places. The ever-changing genetic make-up of SARS-CoV-2 posts a significant challenfge for the research community to identify a robust mechanism to target, bind and confirm the presence of a viral load before it spreads. Synthetic DNA constructs are a novel strategy to design complementary DNA sequences specific for antigens of interest as in this review's case SARS-CoV-2 antigens. Small molecules, complementary DNA and protein-DNA complexes have been known to target analytes in minimal concentrations. This phenomenon can be exploited by nanomaterials which have unique electronic properties such as ballistic conduction. Graphene is one such candidate for designing a device with a very low LOD in the order of zeptomolar and attomolar concentrations. Surface modification will be the significant aspect of the device which needs to have a high degree of sensitivity at the same time as providing a rapid signaling mechanism.

Hydrothermally constructed AgWO4-rGO nanocomposites as an electrode enhancer for ultrasensitive electrochemical detection of hazardous herbicide crisquat.

The advancements in electrode materials with high efficiency has been prioritized to effectively monitor the presence of harmful pesticides concerning the environment. In such a way, we hydrothermally constructed a hybrid AgWO4-rGO nanocomposites for the rapid electrochemical detection of crisquat (CQT). The structural, compositional, morphological and topographical characterization for AgWO4-rGO nanocomposites is thoroughly performed to understand its electrocatalytic properties. The AgWO4-rGO nanocomposites are used as an electrode enhancer (rGO@AgWO4/GCE) for the electrochemical investigations towards CQT detection. The results indicated that the rGO@AgWO4/GCE possessed an excellent catalytic activity with a wide linear detection range 1-1108 µM coupled with an ultrasensitive limit of detection (LOD) 0.0661 µM for electrochemical CQT detection. The rGO@AgWO4/GCE CQT sensor also expressed remarkable sensitivity of 0.6306 µAµM-1cm-2 in addition to good selectivity and reproducibility. Furthermore, the commercial CQT, river water, tap water and washed vegetable water are used as a representative for real world analysis using rGO@AgWO4/GCE and results are highly appreciable for the real time CQT detection. Our work proposes a novel hybrid rGO@AgWO4 nanocomposites reinforced electrodes for ultra-trace level CQT detection with good reliability and can be advocated for real time detection of pesticides.

Fabricating BiOI nanostructures armed catalytic strips for selective electrochemical and SERS detection of pesticide in polluted water.

We have constructed a dual mode catalytic strip equipped with 2D BiOI nanostructures and deployed for dual mode detection sensing of hazardous trichlorophenol (TCP). Synthesized BiOI nanostructures are investigated for its crystal architecture, morphology and chemical composition. The BiOI are loaded onto the catalytic strips with the assistance of gravity offered drying process. The BiOI nanostructures offers a very less charge transfer resistance indicating its superior catalytic properties upon the electrochemical impedance studies. It reflected on providing an excellent limit of detection (LOD) and linear sensing range for TCP in electrochemical mode. For SERS, a thin plasmonic Au layer is sputter coated on BiOI equipped catalytic strips (Au@BiOI) for the TCP detection. An impressive enhancement factor of 107 is obtained for SERS detection of TCP with good LOD of 10-10 M. Fabricated dual mode BiOI based strips are thoroughly examined for operational stability and performance in real time conditions. The fabricated high performance dual mode platform for the detection of hazardous pesticides appears to be a promising prospect for the on-the-spot investigation.

Synthesis of recyclable GO/Cu3(BTC)2/Fe3O4 hybrid nanocomposites with enhanced photocatalytic degradation of aflatoxin B1.

This study evaluated the photocatalytic performance of the activated carbon assisted GO/Cu3(BTC)2/Fe3O4 photocatalyst for aflatoxin B1 (AFB1) degradation under ultraviolet light. The nanocomposite was characterized by Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption-desorption. The numerous factors influencing the degradation efficiency of AFB1 including catalyst dose, pH importance, and contact time were also probed. The elevated degradation performance of AFB1 by 99% was due to a larger surface area and improved GO/Cu3(BTC)2/Fe3O4 photocatalyst. The degradation process followed a pseudo-first-order kinetic model. Moreover, it is possible to quickly isolate the catalyst from the solution and retain successful operation. In the degradation of AFB1, the hole(h+) and the hydroxyl radicals(OH) were found to play a significant role. These studies showed that GO/Cu3(BTC)2/Fe3O4 has high capturing capacity and photoactivity synergy, thereby offering a quick effect, and green solution to AFB1 degradation.

Ultrasensitive electrochemical detection of furazolidone in biological samples using 1D-2D BiVO4@MoS2 hierarchical nano-heterojunction composites armed electrodes.

In this work, the hydrothermally synthesized of BiVO4@MoS2 hierarchical nano-heterojunction composite is employed as a novel electrocatalyst for electrochemical sensing of Furazolidone (FZE) drug by modifying the glassy carbon electrodes (GCE). The Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy are used to thoroughly investigate the functional groups, vibrational modes, crystal structure, elemental composition and surface topography of the heterojunction composite. The physical characterization results revealed the successful construction of 1D-2D BiVO4@MoS2 hierarchical nano-heterojunction composite. When these unique architectures are reinforced on GCE surface, we achieved an enhanced electroactive surface area of 0.154 cm2. The electrochemical performance of 1D-2D BiVO4@MoS2 is examined though cyclic voltammetry and differential pulse voltammetry (DPV) analysis. The BiVO4@MoS2 composites exhibited an excellent electrocatalytic activity in sensing of FZE with superior linear detection ranges of 0.01-14 and 14-614 µM. The limit of detection (LOD) of the BiVO4@MoS2 based sensor is determined to be 2.9 nM which is far superior than other reported FZE sensors. Consequently, it is evident from the investigation that the BiVO4@MoS2 based FZE sensor can be recommended for analyzing real time samples like human urine and blood serum with appreciable recovery.

Incorporation of SiO2 functionalized gC3N4 sheets with TiO2 nanoparticles to enhance the anticorrosion performance of metal specimens in aggressive Cl- environment.

Nowadays, carbon-based nano-structured materials are widely preferred for composite coating as anti-corrosive reinforcement mainly due to its enhanced physical, chemical and mechanical properties. Herein we develop highly efficient Graphitic carbon nitride-Silica-Titania (gC3N4/SiO2/TiO2) ternary nanocomposite are synthesized and it is used as a nanofillers in the corrosive protection layer on the proposed metal specimen (i.e., mild steel specimen) in an aggressive chloride environment. Size, structural and morphological analysis were analysed for the confirmation of presence of particles. gC3N4 is currently earning quite drastic attention, owing to its affordable cost compared to carbon nanotubes and other carbon-based materials, when gC3N4 incorporated with SiO2 and TiO2, the composite matrix greatly improves the mechanical strength of the coating mixture. XRD, XPS, EDS analysis projects excellent formation and presence of the ternary nanocomposites. The particles are well-dispersed in epoxy and organic resin and deposited on the mildsteel panels and it is examined using various surface and structural characterization techniques. The obtained results are very encouraging and the ternary composite coatings can be recommended for real world applications.

Influence of 2D template-assisted (SBA-15) metal oxide Co3O4 for pseudocapacitive and dye degradation application.

Cobalt oxide (Co3O4) is a low-cost material exhibiting excellent physicochemical and photocatalytic properties indicating its potential use for next-generation eco-friendly energy storage and photocatalytic degradation applications. In this study, Co3O4 nanoarcs were synthesized using SBA-15 as a template by microwave-assisted method to form an S15/m-Co3O4 product. Characterization was done by low and wide-angle X-Ray diffraction, and Fourier transformed infra-red spectroscopic studies confirming the presence of S15/m-Co3O4. Scanning Electron Microscope images proved the agglomerated nanotube and nanoarcs like the structure of SBA-15 and S15/m- Co3O4, respectively. Electrochemical studies included cyclic voltammetry, charge/discharge, retention capacity, and electron impedance spectroscopy studies in a 3-electrode system. S15/m-Co3O4 nanoarcs, as the electrode material, was revealed to have a specific capacity of 87.5 C/g in 1 M KOH solution. Upon running 1000 cycles, the material had excellent capacity retention of 87%. The S15/m-Co3O4 product also underwent photocatalytic degradation studies. The Rhodamine R6G dye degradation by S15/m-Co3O4 under UV irradiation exhibited a high degradation percentage of 97.7%, following the first-order kinetics. S15/m-Co3O4 has proven to be biocompatible and can be used to enhance supercapacitors which are an ideal alternative to conventional batteries for energy storage applications. Thus, the data produced proves S15/m-Co3O4 nanoarcs is an excellent electrode material for pseudocapacitive application and a catalyst for photocatalytic degradation of dye molecules.

Enhancing Stability of High-Concentration ß-Tricalcium Phosphate Suspension for Biomedical Application.

We propose a novel process to efficiently prepare highly dispersed and stable Tricalcium Phosphate (ß-TCP) suspensions. TCP is coupled with a polymer to enhance its brittleness to be used as an artificial hard tissue. A high solid fraction of ß-TCP is mixed with the polymer in order to improve the mechanical strength of the prepared material. The high solid fractions led to fast particle aggregation due to Van der Waals forces, and sediments appeared quickly in the suspension. As a result, we used a dispersant, dispex AA4040 (A40), to boost the surface potential and steric hindrance of particles to make a stable suspension. However, the particle size of ß-TCP is too large to form a suspension, as the gravity effect is much more dominant than Brownian motion. Hence, ß-TCP was subjected to wet ball milling to break the aggregated particles, and particle size was reduced to ~300 nm. Further, to decrease sedimentation velocity, cellulose nanocrystals (CNCs) are added as a thickening agent to increase the overall viscosity of suspension. Besides the viscosity enhancement, CNCs were also wrapped with A40 micelles and increase the stability of the suspension. These CNC/A40 micelles further facilitated stable suspension of ß-TCP particles with an average hydration radius of 244.5 nm. Finally, ß-TCP bone cement was formulated with the suspension, and the related cytotoxicity was estimated to demonstrate its applicability for hard tissue applications.

Biogenic Synthesis of Iron Oxide Nanoparticles Using Enterococcus faecalis: Adsorption of Hexavalent Chromium from Aqueous Solution and In Vitro Cytotoxicity Analysis.

The biological synthesis of nanoparticles is emerging as a potential method for nanoparticle synthesis due to its non-toxicity and simplicity. In the present study, a bacterium resistant to heavy metals was isolated from a metal-contaminated site and we aimed to report the synthesis of Fe3O4 nanoparticles via co-precipitation using bacterial exopolysaccharides (EPS) derived from Enterococcus faecalis_RMSN6 strains. A three-variable Box-Behnken design was used for determining the optimal conditions of the Fe3O4 NPs synthesis process. The synthesized Fe3O4 NPs were thoroughly characterized through multiple analytical techniques such as XRD, UV-Visible spectroscopy, FTIR spectroscopy and finally SEM analysis to understand the surface morphology. Fe3O4 NPs were then probed for the Cr(VI) ion adsorption studies. The important parameters such as optimization of initial concentration of Cr(VI) ions, effects of contact time, pH of the solution and contact time on quantity of Cr(VI) adsorbed were studied in detail. The maximum adsorption capacity of the nanoparticles was found to be 98.03 mg/g. The nanoparticles could retain up to 73% of their efficiency of chromium removal for up to 5 cycles. Additionally, prepared Fe3O4 NPs in the concentration were subjected to cytotoxicity studies using an MTT assay. The investigations using Fe3O4 NPs displayed a substantial dose-dependent effect on the A594 cells. The research elucidates that the Fe3O4 NPs synthesized from EPS of E. faecalis_RMSN6 can be used for the removal of heavy metal contaminants from wastewater.

Detection, Contamination, Toxicity, and Prevention Methods of Ochratoxins: An Update Review.

Ochratoxins (OTs) with nephrotoxic, immunosuppressive, teratogenic, and carcinogenic properties are thermostable fungal subordinate metabolites. OTs contamination can occur before or after harvesting, during the processing, packing, distribution, and storage of food. Mold development and mycotoxin contamination can occur in any crop or cereal that has not been stored properly for long periods of time and is subjected to high levels of humidity and temperature. Ochratoxin A (OTA) presents a significant health threat to creatures and individuals. There is also a concern of how human interaction with OTA will also express the remains of OTA from feedstuffs into animal-derived items. Numerous approaches have been studied for the reduction of the OTA content in agronomic products. These methods can be classified into two major classes: inhibition of OTA adulteration and decontamination or detoxification of food. A description of the various mycotoxins, the organism responsible for the development of mycotoxins, and their adverse effects are given. In the current paper, the incidence of OTA in various fodder and food materials is discussed, which is accompanied by a brief overview of the OTA mode of synthesis, physicochemical properties, toxic effects of various types of ochratoxins, and OTA decontamination adaptation methods. To our knowledge, we are the first to report on the structure of many naturally accessible OTAs and OTA metabolism. Finally, this paper seeks to be insightful and draw attention to dangerous OTA, which is too frequently neglected and overlooked in farm duplication from the list of discrepancy studies.

Immobilization of cellulase enzymes on nano and micro-materials for breakdown of cellulose for biofuel production-a narrative review.

Cellulose is a very abundant polymer that is found in nature. Cellulose has been used as a raw material for production of biofuels for many years. However, there are multiple processing steps that are required so that cellulose can be used as a raw material for biofuel production. One of the most important steps is the breakdown of cellulose into intermediate sugars which can then be a viable substrate for biofuel production. Cellulases are enzymes which play a role in the catalysis of the breakdown of cellulose into glucose. Nanomaterials and micromaterials have been gaining a lot of attention over the past few years for its potential in immobilizing enzymes for industrial procedures. Immobilization of enzymes on these nanomaterials has been observed to be of great value due to the improvement in thermal stability, pH stability, regenerative capacity, increase in activity and the reusability of enzymes. Similarly, there have been multiple reports of cellulase enzymes being immobilized on various nanoparticles. The immobilization of these cellulase enzymes have resulted in very efficient processing and provide a great and economic solution for the processing of cellulose for biofuel production. Hence in this paper, we review and discuss the various advantages and disadvantages of enzymes on various available nanomaterials.

High-performance SERS detection of pesticides using BiOCl-BiOBr@Pt/Au hybrid nanostructures on styrofoams as 3D functional substrate.

A 3D flexible domestic waste styrofoam is reported as a surface enhanced Raman scattering (SERS) substrate loaded with BiOCl-BiOBr@Pt/Au semiconductor-plasmonic composites. The hydrothermally prepared BiOCl-BiOBr nanocomposite is thoroughly characterized for its crystal structure using X-Ray diffraction, morphology through scanning electron microscopy, and electronic states of the elements using X-ray photoelectron spectroscopy. The alpha cypermethrin (ACM) is chosen as a model pesticide analyte for SERS investigation. The BiOCl-BiOBr@Pt/Au loaded foam substrate exhibited a high enhancement factor (106) and low limit of detection (10-10 M) upon SERS investigation. The unique architecture of the semiconductor-plasmonic composite enables an efficient charge transfer capability and plasmonic hotspots which aids in the enhancement of target analytes. In order to better demonstrate the versatility towards other pesticides, SERS detection of glyphosate and paraquat pesticides are also performed using the fabricated SERS substrate. The stability of the substrate has been investigated in detail for 30 days and the substrate was highly stable. The BiOCl-BiOBr@Pt/Au-based foam substrate also performed well in rapid real-time sensing of alpha cypermethrin on the kiwi fruit exocarp at lower level concentrations. Graphical abstract.

Bifunctional bimetallic heterojunction material based on Al2O3/ZnO micro flowers for electrochemical sensing and catalysis.

We report the synthesis, characterization, electrochemical sensing and catalytic capability of the bimetallic heterojunction Al2O3/ZnO micro flowers (AZ MFs). In order to prepare this bifunctional material, the facile hydrothermal process was adopted. The material was thoroughly characterized for the crystal structure and morphology with Powder XRD, XPS and FE-SEM. The investigation of electrochemical sensing was done using hydroquinone (HQ) and the chemical catalysis was using rhodamine B (RhB) with our bimetallic Al2O3/ZnO micro flowers as these are harmful industrial pollutants. The process parameters like the influence of scan rate and pH was efficiently optimized for the electrochemical detection of HQ and kinetics for the time dependent catalytic degradation of RhB dye. The linear relationship between the peak current and the concentration of HQ was found to be in the range of 0.125-20.25 µM with an impressive detection limit of 11.2 nM. In the chemical catalytic degradation of the RhB dye, our bimetallic material thrived well during the reaction and degraded the material in 10 min. The performance of bimetallic Al2O3/ZnO micro flowers towards HQ detection and RhB degradation shows good stability, reproducibility and it can be efficiently utilized to treat the environmental pollutants.

Estimating amperometric spike parameters resulting from quantal exocytosis using curve fitting seeded by a matched-filter algorithm.

BACKGROUND: Quantal exocytosis of oxidizable neurotransmitters can be detected as spikes of amperometric current using electrochemical microelectrodes. Measurements of spike parameters indicate the maximal transmitter flux, flux duration, and amount of transmitter released from individual vesicles. Automated analysis algorithms need to reject spikes that overlap in time. In addition, many spikes are preceded by small amplitude "foot" signals, attributed to slow release of transmitter through a fusion pore. Accurate pre-spike baseline determination is essential for estimating fusion-pore duration and the amount of transmitter released through the fusion pore. NEW METHOD: We developed an estimation approach that is based on fitting a multi-exponential function to the data. Our previously described matched-filter algorithm is used to identify the sections of data to fit and provides seed values to facilitate convergence of the iterative fit. The new estimation algorithm includes overlap rejection, a two-step fitting procedure and a novel baseline estimation procedure. RESULTS: Histograms of spike parameters demonstrate excellent agreement of the new approach with manually computed parameters. COMPARISON WITH EXISTING METHODS: Parameter estimates generated using the new approach are closer to blind manual estimates than commonly used existing methods. The improved performance is due to better detection of valid spikes and rejection of overlapping spikes. Moreover, since the complete time course of the spike is fit to a function, more complete information about the spike time course is captured. CONCLUSIONS: The matched-filter seeded algorithm reliably rejects overlaps and estimates spike and foot signal parameters in a fully automated manner.

Lanthanide Doped Near Infrared Active Upconversion Nanophosphors: Fundamental Concepts, Synthesis Strategies, and Technological Applications.

Near infrared (NIR) light utilization in a range of current technologies has gained huge significance due to its abundance in nature and nondestructive properties. NIR active lanthanide (Ln) doped upconversion nanomaterials synthesized in controlled shape, size, and surface functionality can be combined with various pertinent materials for extensive applications in diverse fields. Upconversion nanophosphors (UCNP) possess unique abilities, such as deep tissue penetration, enhanced photostability, low toxicity, sharp emission peaks, long anti-Stokes shift, etc., which have bestowed them with prodigious advantages over other conventional luminescent materials. As new generation fluorophores, UCNP have found a wide range of applications in various fields. In this Review, a comprehensive overview of lanthanide doped NIR active UCNP is provided by discussing the fundamental concepts including the different mechanisms proposed for explaining the upconversion processes, followed by the different strategies employed for the synthesis of these materials, and finally the technological applications of UCNP, mainly in the fields of bioimaging, drug delivery, sensing, and photocatalysis by highlighting the recent works in these areas. In addition, a brief note on the applications of UCNP in other fields is also provided along with the summary and future perspectives of these materials.

Fog-Harvesting Properties of Dryopteris marginata: Role of Interscalar Microchannels in Water-Channeling.

Several flora and fauna species found in arid areas have adapted themselves to collect water by developing unique structures and to intake the collected moisture. Apart from the capture of the moisture and fog on the surface, water transport and collection both play an important part in fog-harvesting systems as it prevents the loss of captured water through evaporation and makes the surface available for the capture of water again. Here, we report the remarkable fog collection and water-channeling properties of Dryopteris marginata. The surface of D. marginata has developed an integrated system of multiscale channels so that the water spreads quickly and is transported via these channels very efficiently. These integrated multiscale channels have also been replicated using a facile soft lithography technique to prepare biomimetic surfaces and it has been proved that it is the surface architecture that plays a role in the water transport rather than the material's properties (waxes present on the surface of the leaves). Based on our studies, we infer that the microlevel hierarchy of the structures make the surface hydrophilic and the multiscale channels allow the efficient passage and transport of water. The understanding of the efficient and well-directed water transport and collection in D. marginata is expected to provide valuable insights to design efficient surfaces for fog-harvesting applications.

A matched-filter algorithm to detect amperometric spikes resulting from quantal secretion.

BACKGROUND: Electrochemical microelectrodes located immediately adjacent to the cell surface can detect spikes of amperometric current during exocytosis as the transmitter released from a single vesicle is oxidized on the electrode surface. Automated techniques to detect spikes are needed in order to quantify the spike rate as a measure of the rate of exocytosis. NEW METHOD: We have developed a Matched Filter (MF) detection algorithm that scans the data set with a library of prototype spike templates while performing a least-squares fit to determine the amplitude and standard error. The ratio of the fit amplitude to the standard error constitutes a criterion score that is assigned for each time point and for each template. A spike is detected when the criterion score exceeds a threshold and the highest-scoring template and the time of peak score is identified. The search for the next spike commences only after the score falls below a second, lower threshold to reduce false positives. The approach was extended to detect spikes with double-exponential decays with the sum of two templates. RESULTS: Receiver Operating Characteristic plots (ROCs) demonstrate that the algorithm detects >95% of manually identified spikes with a false-positive rate of ∼2%. COMPARISON WITH EXISTING METHODS: ROCs demonstrate that the MF algorithm performs better than algorithms that detect spikes based on a derivative-threshold approach. CONCLUSIONS: The MF approach performs well and leads into approaches to identify spike parameters.

Antitumor and cytotoxic effects of Phyllanthus polyphyllus on Ehrlich ascites carcinoma and human cancer cell lines.

To evaluate the antitumor and cytotoxic activity of methanol extract of Phyllanthus polyphyllus (MPP) in mice and human cancer cell lines, the antitumor activity of MPP was evaluated against an Ehrlich ascites carcinoma (EAC) tumor model. The activity was assessed using survival time, hematological studies, lipid peroxidation (LPO), antioxidant enzymes such as superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione S-transferase (GST), solid tumor mass, and short-term in vitro cytotoxicity. The cytotoxic activity of MPP was evaluated using human breast cancer (MCF7), colon cancer (HT29), and liver cancer (HepG2) cell lines Oral administration of MPP (200 and 300 mg/kg) increased the survival time and significantly reduced the solid tumor volume in a dose-dependent manner. Hematological parameters, protein, and packed cellular volume (PCV), which were altered by tumor inoculation, were restored. MPP significantly decreased the levels of LPO, GPx, GST, and significantly increased the levels of SOD and CAT. In a cytotoxicity study against human cancer cell lines, MPP was found to have IC50 values of 27, 42 and 38 microg/ml on MCF-7, HT-29, and HepG2 cells respectively. MPP possessed significant antitumor and cytotoxic activity on EAC and human cancer cell lines.