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1.
Chemosphere ; 349: 140892, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38070614

ABSTRACT

Carissa carandas, a traditional medicinal herb with a high concentration of antioxidant phytochemicals, has been used for thousands of years in the Ayurveda, Unani, and homoeopathic schools of medicine. By employing Carissa carandas bark extract as a reducing and capping agent in green biosynthesis, we extend this conventional application to produce CoFe2O4 and CoFe2O4@Ag nanocomposite. A variety of techniques have been used to characterize the synthesised nanocomposite, including UV-Vis, FTIR, XRD, FESEM, EDX, and BET. The CoFe2O4 and CoFe2O4@Ag nanocomposite demonstrated promising antibacterial action against human bacterial pathogens like B. subtilis and S. aureus as gram positive and P. aeruginosa and E. coli as gram negative with inhibition zones of 24.3 ± 0.57, 17.4 ± 0.75 and 20.5 ± 0.5, 19.8 ± 1.6 mm respectively, and the obtained results were superior to the nanocomposite without silver. Moreover, in-vitro cytotoxicity effects of biosynthesized CoFe2O4 and CoFe2O4@Ag were performed on the human breast cancer cell MCF-7. It was found that the MCF-7 cells' 50% inhibitory concentration (IC50) was 60 µg/mL. Additionally, biosynthesized CoFe2O4 and CoFe2O4@Ag nanocomposite was used to demonstrate the photocatalytic eradication of Rhodamine Blue (RhB). Due to the addition of Ag, which increases surface area, conductivity, and increased charge carrier separation, the CoFe2O4@Ag nanocomposite exhibits a high percentage of photocatalytic degradation of ⁓ 98% within 35 min under UV light irradiation. The photocatalytic performance of as-synthesised nanocomposite was evaluated using dye degradation-adsorption in both natural light and dark condition. Under dark conditions, it was found that 2 mg mL-1 CoFe2O4@Ag in RhB aqueous solution (5 ppm) causes dye adsorption in 30 min with an effectiveness of 72%. Consequently, it is anticipated that the CoFe2O4@Ag nanocomposite will be a promising photocatalyst and possibly a noble material for environmental remediation applications.


Subject(s)
Metal Nanoparticles , Nanocomposites , Humans , Escherichia coli , Staphylococcus aureus , Anti-Bacterial Agents/toxicity , Anti-Bacterial Agents/chemistry , Silver/toxicity , Silver/chemistry , Nanocomposites/toxicity , Nanocomposites/chemistry , Metal Nanoparticles/chemistry
2.
Anal Sci ; 39(8): 1413-1423, 2023 Aug.
Article in English | MEDLINE | ID: mdl-37280486

ABSTRACT

The study reports the synthesis of chemosensor (E)-2-(1-(3-aminophenyl)ethylideneamino)benzenethiol (C1), a highly sensitive, colorimetric metal probe that shows distinct selectivity for the detection of Cu2+ ion in various real water samples. Upon complexation with Cu2+ in CH3OH/H2O (60:40 v/v) (aqueous methanol), the C1 demonstrate significant enhancement in the absorption at 250 nm and 300 nm with a color change from light yellow to brown which was visualized using naked-eye. Therefore, these properties make C1 as an effective candidate for on-site Cu2+ ions detection. The emission spectrum of C1 illustrated "TURN-ON" recognition of Cu2+ with a limit of detection (LOD) of 46 nM. Furthermore, Density Functional Theory (DFT) calculations were performed to better understand the interactions between C1 and Cu2+. The obtained results suggested that the electron clouds present around the -NH2 in nitrogen and sulfur in -SH play a pivotal role in the formation of a stable complex. The computational results were in good agreement with the experimental UV-visible spectrometry results.

3.
Bioelectrochemistry ; 147: 108212, 2022 Oct.
Article in English | MEDLINE | ID: mdl-35870314

ABSTRACT

The analysis of ß-blockers in pharmaceutical, biological and environmental samples has gained much interest due to their wide applications. The aim of this study was to develop an enzyme-based biosensor using hexagonal-shaped low-dimensional Bi2Se3 NPs decorated with laccase through polyaziridine (PAZ) modified glassy carbon electrode (Lac/PAZ-Bi2Se3 NPs/GCE). Surface properties were examined using SEM, TEM, EDX, XRD, XPS, FTIR, UV-Visible, and zeta potential. Electrochemical studies were performed with cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The enzymatic biosensor exhibited excellent catalytic activity towards the oxidation of ATN at +1.05 V (vs Ag/AgCl). Under the optimum experimental conditions, Ip (µA) was linearly related to the concentrations of ATN in the range of 3 to 130 µM (R2 = 0.9972) with an LOD of 0.15 µM and 0.21 µM with and without Lac enzyme. Additionally, the validation of the biosensor was tested to determine ATN on within a day and between-day basis. The biosensor was applied successfully to detect ATN in real samples. The obtained recoveries range from 98.5 % to 99.2 % with an RSD (n = 5) of 0.95 (±0.02). The findings of this study have potential biomedical applications in drug detection employing a promising nano electrode sensor of Lac/PAZ-Bi2Se3 NPs/GCE.


Subject(s)
Laccase , Polyethyleneimine , Atenolol , Bismuth , Electrochemical Techniques/methods , Electrodes , Pharmaceutical Preparations , Selenium Compounds
4.
Water Sci Technol ; 83(7): 1714-1727, 2021 Apr.
Article in English | MEDLINE | ID: mdl-33843754

ABSTRACT

Size-controlled Pb0.06Fe0.7O3 nanoparticles (Pb-FeONPs) were fabricated by the thermal co-precipitation method and characterized by FE-SEM, EDX, XRD, and IR techniques. The SEM and XRD images showed the average size distribution and average crystallite size of 19.21 nm and 4.9 nm, respectively. The kinetic model of Congo Red (CR) adsorption onto Pb-FeONPs was verified and found to be a pseudo-second-order reaction. The Langmuir plot was better fitted (R2 = 0.990) than other isotherm models with a Qmax (mg/g) of 500 for Congo Red (CR) dye in 40 min. The double-layer statistical physics model based on two energies was used to calculate the significant parameters. The n (stoichiometric coefficient) values obtained from the statistical physics double-layer model were found to be 0.599, 0.593, and 0.565, which are less than 1, indicating the multi-docking process. The regeneration of Pb-FeONPs was used for up to 5 cycles effectively, making the material highly economical. The Pb-FeONPs were fruitfully applied for the removal of CR dye from wastewater on a laboratory and industrial scale.


Subject(s)
Congo Red , Water Pollutants, Chemical , Adsorption , Congo Red/analysis , Hydrogen-Ion Concentration , Kinetics , Lead , Physics
5.
J Fluoresc ; 31(3): 625-634, 2021 May.
Article in English | MEDLINE | ID: mdl-33635498

ABSTRACT

A Schiff-base 2-((E)-(3-(prop-1-en-2-yl)phenylimino)methyl)-4-nitrophenol (Receptor 1) colorimetric probe was synthesized and its UV-visible and fluorescence spectral properties for the sensing of Cu+ 2 ions in CH3OH/H2O (60:40,v/v) solvent system was explored. The Receptor 1 showed the discriminating spectral behavior with the addition of Cu2+ ions solution. The other metal ions showed no significant effect towards Receptor 1. Moreover, the addition of Cu2+ ions to the Receptor 1 demonstrated the shift in the peak towards longer wavelength of 405 nm due to the ligand to metal charge transfer (LMCT) effect. The red-shift and new peak at 405 nm are due to the deprotonation of the -OH group and formation of complex and O-Cu covalent bond, respectively. A slight increase in the Cu2+ ion concentration exhibited strong absorption and fluorescence properties, leading to the spontaneous change in color from pale yellow to orange. Additionally, Density Functional Theory (DFT) studies were performed to investigate the interaction of Cu2+ ions with Receptor 1. The decrease in the energies (3.59062 kcal/mol to 0.36028 kcal/mol) of Cu2+-Receptor-1 complex compared to Receptor 1 confirms the strong interaction with high stability. The association constant (Ka) of Cu2+-Receptor-1 complex was found as 175000 M- 1. The limit of detection (LOD) was calculated and noted as 179 nM.

6.
Sci Rep ; 10(1): 18391, 2020 10 27.
Article in English | MEDLINE | ID: mdl-33110140

ABSTRACT

The human sweet taste receptor (T1R2) monomer-a member of the G-protein coupled receptor family that detects a wide variety of chemically and structurally diverse sweet tasting molecules, is known to pose a significant threat to human health. Protein that lack crystal structure is a challenge in structure-based protein design. This study focused on the interaction of the T1R2 monomer with rebaudioside A (Reb-A), a steviol glycoside with potential use as a natural sweetener using in-silico and biosensing methods. Herein, homology modelling, docking studies, and molecular dynamics simulations were applied to elucidate the interaction between Reb-A and the T1R2 monomer. In addition, the electrochemical sensing of the immobilised T1R2-Reb-A complex with zinc oxide nanoparticles (ZnONPs) and graphene oxide (GO) were assessed by testing the performance of multiwalled carbon nanotube (MWCNT) as an adsorbent experimentally. Results indicate a strong interaction between Reb-A and the T1R2 receptor, revealing the stabilizing interaction of the amino acids with the Reb-A by hydrogen bonds with the hydroxyl groups of the glucose moieties, along with a significant amount of hydrophobic interactions. Moreover, the presence of the MWCNT as an anchor confirms the adsorption strength of the T1R2-Reb-A complex onto the GO nanocomposite and supported with electrochemical measurements. Overall, this study could serve as a cornerstone in the development of electrochemical immunosensor for the detection of Reb-A, with applications in the food industry.


Subject(s)
Diterpenes, Kaurane/chemistry , Models, Chemical , Receptors, G-Protein-Coupled/chemistry , Sweetening Agents/chemistry , Taste Buds/chemistry , Adsorption , Biosensing Techniques , Computer Simulation , Humans , Molecular Docking Simulation , Molecular Dynamics Simulation , Protein Binding
7.
Sci Rep ; 10(1): 13563, 2020 08 11.
Article in English | MEDLINE | ID: mdl-32782411

ABSTRACT

For the first time, we report a novel electrochemical sensor for the simultaneous detection of ethambutol (ETB) and pyrazinamide (PZM) using 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim][BF4]) ionic liquid (IL) assimilated with multiwalled carbon nanotubes (MWCNTs) decorated cobalt ferrite nanoparticles (CoFe2O4NPs) on the surface of glassy carbon electrode (GCE). The surface morphological and electrochemical properties of the IL@CoFe2O4NPs@MWCNTs was characterized with X-ray diffraction (XRD), transmission electron microscope (TEM), thermogravimetric analysis (TGA), fourier transform infrared spectroscopy (FTIR) and cyclic voltammetry (CV), differential pulse voltammetry (DPV) respectively. Moreover, the obtained results of CV demonstrated that the 9-folds enhancement in the electrochemical signals was achieved with IL@CoFe2O4NPs@MWCNTs@GCE compared to that of a bare GCE. Additionally, the simultaneous electrochemical detection of ETB and PZM was successfully accomplished using IL@CoFe2O4NPs@MWCNTs over a wide-range of concentration with good limit of detection (3S/m) of 0.0201 and 0.010 µM respectively. The findings of this study identify IL@CoFe2O4NPs@MWCNTs@GCE has promising abilities of simultaneous detection of ETB and PZM in pharmaceutical formulations.

8.
Sci Rep ; 10(1): 5052, 2020 03 19.
Article in English | MEDLINE | ID: mdl-32193477

ABSTRACT

Presently, one of the most important aspects for the development of enzymatic biofuel cells (EBFCs) is to synthesize the novel electrode materials that possess high current density, low open-circuit voltage (OCV) and long-term stability. To achieve the above attributes, lots of new strategies are being used by the researchers for the development of advanced materials. Nowadays, nanomaterials and nanocomposites are the promising material that has been utilized as effective electrode material in solar cells, supercapacitors and biofuel cells application. Herein, we account for a novel electrocatalyst as electrode material that comprised ZnO nanoparticles decorated on the surface of polyindole (PIn)-multi-walled carbon nanotube (MWCNT), for the immobilization of glucose oxidase (GOx) enzyme and mediator (Ferritin). The PIn-MWCNT scaffold is prepared via in situ chemical oxidative polymerization of indole on the surface of MWCNT and assessed by myriad techniques. The micrograph of scanning electron microscopy (SEM) designated the interconnected morphology of MWCNTs in the polymer matrix. X-ray diffraction spectroscopy (XRD) and Fourier transform infrared spectroscopy (FTIR), confirm the crystallinity and different functional groups available in the synthesized material, respectively. The electrochemical assessment demonstrates that the ZnO/PIn-MWCNT/Frt/GOx nanobiocatalyst exhibits much higher electrocatalytic activity towards the oxidation of glucose with a maximum current density of 4.9 mA cm-2 by consuming 50 mM glucose concentration in phosphate buffer saline (PBS) (pH 7.4) as the testing solution by applying 100 mVs-1 scan rates. The outcomes reflect that the as-prepared ZnO/PIn-MWCNTs/Frt/GOx biocomposite is a promising bioanode for the development of EBFCs.

9.
Sci Rep ; 9(1): 18414, 2019 12 05.
Article in English | MEDLINE | ID: mdl-31804530

ABSTRACT

The metal complexes can demonstrate various interesting biological activities in the human body. However, the role of certain metal ions for specific cell activities is still subject to debate. This study is aimed at comparing the thermochemical properties of neotame (artificial sweetener) and α, ß-fructose in gas phase and water medium. The interaction of α and ß-fructose, neotame with monovalent and divalent metal ions was studied and comprehended by density functional theory (DFT) using B3LYP functional, 6-311 + G (d, p) and D3 basis set. Metal ion affinities (MIA) values depicted that ionic radius of metal ions played an important role in the interaction of α, ß-fructose and neotame. The ∆G parameter was calculated to predict and understand the interaction of metal ions with α and ß-fructose, neotame. The results suggested that the presence of hydroxyl groups and oxygen atoms in sugar molecules acted as preferred sites for the binding and interaction of mono and divalent ions. For the first time computational study has been introduced in the present study to review the progress in the application of metal binding with sugar molecules especially with neotame. Moreover, voltammetric behaviour of neotame-Zn2+ was studied using cyclic and differential pulse voltammetry. The obtained results suggest that the peak at -1.13 V is due to the reduction of Zn2+ in 0.1 M phosphate buffer medium at pH 5.5. Whereas, addition of 6-fold higher concentration of neotame to the ZnCl2.2H2O resulted in a new irreversible cathodic peak at -0.83, due to the reduction of neotame-Zn2+ complex. The Fourier transform infrared spectroscopy (FTIR) results indicates that the ß-amino group (-NH) and carboxyl carbonyl (-C = O) groups of neotame is participating in the chelation process, which is further supported by DFT studies. The findings of this study identify the efficient chelation factors as major contributors into metal ion affinities, with promising possibilities to determine important biological processes in cell wall and glucose transmembrane transport.

10.
Sci Rep ; 9(1): 7873, 2019 05 27.
Article in English | MEDLINE | ID: mdl-31133671

ABSTRACT

This work deals with first-principles and in silico studies of graphene oxide-based whole-cell selective aptamers for cancer diagnostics utilising a tunable-surface strategy. Herein, graphene oxide (GO) was constructed as a surface-based model with poly(N-isopropylacrylamide) (PNIPAM) covalently grafted as an "on/off"-switch in triggering interactions with the cancer-cell protein around its lower critical solution temperature. The atomic building blocks of the aptamer and the PNIPAM adsorbed onto the GO was investigated at the density functional theory (DFT) level. The presence of the monomer of PNIPAM stabilised the system's π-π interaction between GO and its nucleobases as confirmed by higher bandgap energy, satisfying the eigenvalues of the single-point energy observed rather than the nucleobase and the GO complex independently. The unaltered geometrical structures of the surface emphasise the physisorption type interaction between the nucleobase and the GO/NIPAM surface. The docking result for the aptamer and the protein, highlighted the behavior of the PNIPAM-graft-GO  is exhibiting globular and extended conformations, further supported by molecular dynamics (MD) simulations. These studies enabled a better understanding of the thermal responsive behavior of the polymer-enhanced GO complex for whole-cell protein interactions through computational methods.


Subject(s)
Acrylic Resins/chemistry , Aptamers, Nucleotide/chemistry , Graphite/chemistry , Neoplasms/diagnosis , Adsorption , Biosensing Techniques/methods , Density Functional Theory , Molecular Docking Simulation , Molecular Dynamics Simulation
11.
J Photochem Photobiol B ; 188: 159-176, 2018 Nov.
Article in English | MEDLINE | ID: mdl-30308399

ABSTRACT

Owing to the emerging applications of DNA-functionalized TiO2 nanocrystals towards DNA damage detection, it is inevitable to understand the better chemistry as well as in-depth molecular interaction phenomena. Fundamentally, energy difference underlies the layer-by-layer construction, resulted in the increase of the interaction energy and thus, altering the electrochemical behavior. Herein, Density functional theory (DFT) calculations were performed using DMol3 and DFTB+ codes successfully to elucidate the structural, electronics, and vibrational properties of the layer-by-layer components composing ss-DNA/dopamine/TiO2/FTO. The obtained results are in good agreement with the experimental findings. The band gaps of FTO and TiO2 were computationally obtained at 3.335 and 3.136 eV which are comparable with the experimental data (3.500 eV; FTO and 3.200 eV; TiO2). Frontier orbital analysis is also considered to elucidate their electron transfer phenomena. Further, a 100 ns MD simulations are carried out using canonical ensemble embedded with COMPASS-Universal Forcefields generating useful thermodynamics parameters. Binding energies indicate increasing interaction energies for the layer-by-layer nanosystem, in agreement with the increasing diameter of electrochemical impedance spectroscopy (EIS) semicircle. Our results reveal the fundamental understanding of the DNA-functionalized TiO2 nanocrystals down to molecular and electronic level and further, paving a way of its application towards nanoelectrochemical DNA biosensors.


Subject(s)
DNA Damage , DNA/chemistry , Light , Nanoparticles/chemistry , Titanium/chemistry , Biosensing Techniques , DNA Damage/drug effects , DNA Damage/radiation effects , DNA, Single-Stranded/analysis , DNA, Single-Stranded/metabolism , Dielectric Spectroscopy , Dopamine/chemistry , Fluorine/chemistry , Molecular Dynamics Simulation , Nanoparticles/toxicity , Quantum Theory , Tin Compounds/chemistry
12.
J Biomol Struct Dyn ; 36(6): 1402-1416, 2018 May.
Article in English | MEDLINE | ID: mdl-28463066

ABSTRACT

Designing of rapid, facile, selective, and cost-effective biosensor technology is a growing area for the detection of various classes of pesticides. The biosensor with these features can be achieved only through the various bio-components using different transducers. This study, therefore, focuses on the usage of molecular docking, specificity tendencies, and capabilities of proteins for the detection of pesticides. Accordingly, the four transducers, acetylcholinesterase (ACH), cytochromes P450 (CYP), glutathione S-transferase (GST), and protein kinase C (PKC) were selected based on their applications including neurotransmitter, metabolism, detoxification enzyme, and protein phosphorylation. Then after molecular docking of the pesticides, fenobucarb, dichlorodiphenyltrichloroethane (DDT), and parathion onto each enzyme, the conformational behavior of the most stable complexes was further analyzed using 50 ns Molecular Dynamics (MD) simulations carried out under explicit water conditions. In the case of protein kinase C (PKC) and cytochrome P450 3A4 enzyme (CYP), the fenobucarb complex showed the most suitable combination of free energy of binding and inhibition constant -4.42 kcal/mol (573.73 µM) and -5.1 kcal/mol (183.49 µM), respectively. Parathion dominated for acetylcholinesterase (ACH) with -4.57 kcal/mol (448.09 µM) and lastly dichlorodiphenyltrichloroethane for glutathione S-transferase (GST), -5.43 kcal/mol (103.88 µM). The RMSD variations were critical for understanding the impact of pesticides as they distinctively influence the energetic attributes of the proteins. Overall, the outcomes from the extensive analysis provide an insight into the structural features of the proteins studied, thereby highlighting their potential use as a substrate in biorecognition sensing of pesticide compounds.


Subject(s)
Enzymes/chemistry , Pesticides/chemistry , Biosensing Techniques/methods , Molecular Docking Simulation/methods , Molecular Dynamics Simulation , Protein Binding , Proteins/chemistry
13.
Biosens Bioelectron ; 102: 136-149, 2018 Apr 15.
Article in English | MEDLINE | ID: mdl-29128716

ABSTRACT

A smartphone is a facile, handy-analytical device that makes our lives comfortable and stress-free in terms of health care diagnostic assessments. Due to recent advancements in the technology and the introduction of user friendly operating systems and applications, the smartphones have replaced laptops and desktop computers. Taking this fact into account, researchers have designed sensing systems which are more compatible with smartphones. Consequently, these devices are attracting the attention of researchers from fields such as telemedicine, biotechnology, chemical sciences and environmental sciences. In this review, our focus is on recent advances on smartphone based sensing and diagnosis applications.


Subject(s)
Biosensing Techniques , Point-of-Care Systems , Smartphone , Animals , Biosensing Techniques/instrumentation , Biosensing Techniques/methods , Equipment Design , Humans , Mobile Applications , Smartphone/instrumentation , Telemedicine/instrumentation , Telemedicine/methods
14.
J Photochem Photobiol B ; 178: 560-567, 2018 Jan.
Article in English | MEDLINE | ID: mdl-29253815

ABSTRACT

Plant extracts continue gaining significant prominence in green synthesis of silver nanoparticles (AgNPs), due to their potential applications in nano-medicine and material engineering. This work reports on green synthesis of silver nanoparticles (AgNPs) from aqueous extracts of Iboza Riparia leaf and Ilex Mitis root bark with diterpenes (DTPs) and saponins (SPNs) as major components. After TEM, DLS, TGA/DSC, ATR, XRD and UV-Vis characterization, the relevant cytotoxicity studies were conducted with the MTT assay on human embryonic kidney cells (HEK293T) followed by antioxidant activity with ABTS. Overall, the AgNPs-DTPs (156nm) were found to be less toxic with 49.7% cell viability, while AgNPs-SPNs (50nm) and AgNPs-PVA (44nm) had cell viability of 40.8 and 28.0% respectively at 400µM. Based on the cytotoxicity and antioxidant activity, it is fair to report that these plant extracts have potential reducing and capping agents as they retain chemical properties on the surface of the nanoparticles.


Subject(s)
Ilex/chemistry , Metal Nanoparticles/chemistry , Silver/chemistry , Antioxidants/chemistry , Calorimetry, Differential Scanning , Cell Survival/drug effects , Diterpenes/chemistry , Diterpenes/isolation & purification , Green Chemistry Technology , HEK293 Cells , Humans , Ilex/metabolism , Metal Nanoparticles/toxicity , Particle Size , Plant Extracts/chemistry , Plant Leaves/chemistry , Plant Leaves/metabolism , Plant Roots/chemistry , Plant Roots/metabolism , Saponins/chemistry , Saponins/isolation & purification , Spectrophotometry, Ultraviolet , X-Ray Diffraction
15.
J Photochem Photobiol B ; 162: 199-207, 2016 Sep.
Article in English | MEDLINE | ID: mdl-27380295

ABSTRACT

The naturally occurring biomolecules present in the plant extracts have been identified to play an active role in the single step formation of nanoparticles with varied morphologies and sizes which is greener and environmentally benign. In the present work, spherical zinc oxide nanoparticles (ZnO NPs) of 2-4nm size were synthesized using aqueous extract of fallen Jacaranda mimosifolia flowers (JMFs), treated as waste. The microwave assisted synthesis was completed successfully within 5min. Thereafter, phase identification, morphology and optical band gap of the synthesized ZnO NPs were done using X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and UV-Visible spectroscopy techniques. The composition of JMFs extract was analyzed by gas chromatography-mass spectrometry (GC-MS) and the ZnO NPs confirmation was further explored with fourier transform infrared spectroscopy (FTIR). The GC-MS results confirmed the presence of oleic acid which has high propensity of acting as a reducing and capping agent. The UV-Visible data suggested an optical band gap of 4.03eV for ZnO NPs indicating their small size due to quantum confinement. Further, facet specific adsorption of oleic acid on the surface of ZnO NPs was studied computationally to find out the impact of biomolecules in defining the shape and size of NPs. The viability of gram negative Escherichia coli and gram positive Enterococcus faecium bacteria was found to be 48% and 43%, respectively at high concentration of NPs.


Subject(s)
Bignoniaceae/chemistry , Flowers/chemistry , Nanoparticles , Nanotechnology , Plant Extracts/chemistry , Zinc Oxide/chemistry , Zinc Oxide/pharmacology , Adsorption , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Chemistry Techniques, Synthetic , Escherichia coli/drug effects , Models, Molecular , Particle Size , Zinc Oxide/chemical synthesis
16.
Biosens Bioelectron ; 83: 45-53, 2016 Sep 15.
Article in English | MEDLINE | ID: mdl-27104584

ABSTRACT

The present study involves the development of a sensitive electrochemical biosensor for the determination of capsaicin extracted from chilli fruits, based on a novel signal amplification strategy using enzyme technology. For the first time, platinum electrode modified with multiwalled carbon nanotubes where phenylalanine ammonia-lyase enzyme was immobilized using nafion was characterized by attenuated total reflectance infrared spectroscopy, transmittance electron microscopy and thermo-gravimetric analysis supported by computational methods. Cyclic and differential pulse voltammetry measurements were performed to better understand the redox mechanism of capsaicin. The performance of the developed electrochemical biosensor was tested using spiked samples with recoveries ranging from 98.9 to 99.6%. The comparison of the results obtained from bare and modified platinum electrodes revealed the sensitivity of the developed biosensor, having a detection limit (S/N=3) of 0.1863µgmL(-1) and electron transfer rate constant (ks) of 3.02s(-1). Furthermore, adsorption and ligand-enzyme docking studies were carried out to better understand the redox mechanisms supported by density functional theory calculations. These results revealed that capsaicin forms hydrogen bonds with GLU355, GLU541, GLU586, ARG and other amino acids of the hydrophobic channel of the binding sites thereby facilitating the redox reaction for the detection of capsaicin.


Subject(s)
Capsaicin/analysis , Electrochemical Techniques/methods , Enzymes, Immobilized/metabolism , Phenylalanine Ammonia-Lyase/metabolism , Rhodotorula/enzymology , Biosensing Techniques/methods , Capsaicin/metabolism , Capsicum/chemistry , Electrodes , Enzymes, Immobilized/chemistry , Fluorocarbon Polymers/chemistry , Limit of Detection , Molecular Docking Simulation , Nanotubes, Carbon/chemistry , Nanotubes, Carbon/ultrastructure , Oxidation-Reduction , Phenylalanine Ammonia-Lyase/chemistry , Rhodotorula/chemistry
17.
Biosens Bioelectron ; 77: 116-23, 2016 Mar 15.
Article in English | MEDLINE | ID: mdl-26397423

ABSTRACT

In this study a novel cyctochrome c modified nanocomposite electrochemical biosensor was developed for the electrochemical determination of rebaudioside A in different food samples. The electrode surface was fabricated with graphene oxide assimilated with gold nanoparticles decorated on multiwalled carbon nanotubes/cytochrome c. The developed biosensor exhibited a 10-fold enhancement in the differential pulse voltammetry signal carried out at pH 11.0 in a 0.1M borate buffer. Under the optimized conditions, Ip (µA) was proportional to the rebaudioside A concentration in the range of 0.001-0.05 mM (R(2)=0.8308) and 0.075-1.25 mM (R(2)=0.9920) with a detection limit (S/N=3) of 0.264 µM. Results of this study revealed that cyctochrome c was adsorbed tightly onto the surface of the modified electrode and showed an enzymatic catalytic activity towards the quasi-reversible reduction of rebaudioside A at -0.1 V (vs Ag/AgCl). The direct electron transfer by cytochrome c was further supported by HOMO-LUMO calculations performed at the density functional theory level. Additionally, the molecular docking simulations predicted a stronger binding affinity of rebaudioside A towards cytochrome c, thus supporting their host-guest relationship. The use of novel electrode materials in this study demonstrates the application of the electrochemical biosensor in the food industry.


Subject(s)
Biosensing Techniques , Conductometry/instrumentation , Cytochromes c/chemistry , Diterpenes, Kaurane/analysis , Food Analysis/instrumentation , Enzymes, Immobilized/chemistry , Equipment Design , Equipment Failure Analysis , Microchemistry/instrumentation , Reproducibility of Results , Sensitivity and Specificity
18.
Biosens Bioelectron ; 67: 200-7, 2015 May 15.
Article in English | MEDLINE | ID: mdl-25216979

ABSTRACT

A highly sensitive and novel electrochemical sensor for the detection of neotame using differential pulse voltammetry with a modified glassy carbon electrode is presented. The method was further customized by the fabrication of the electrode surface with copper nanoparticles-ammonium piperidine dithiocarbamate-mutiwalled carbon nanotubes assimilated with ß-cyclodextrin. The multiwalled carbon nanotubes assimilated with ß-cyclodextrin/glassy carbon electrode exhibited catalytic activity towards the oxidation of neotame at a potential of 1.3 V at pH 3.0. The transmission electron microscopy, thermogravimetric analysis, frontier transform infrared spectroscopy and cyclic voltammetry were employed to characterize the electrochemical sensor. The sensitivity and detection limits of the electrode increased two-fold in contrast to the ß-CD-MWCNTs/GCE sensor. The developed method was successfully applied for the determination of neotame in food samples, with results similar to those achieved by our modified capillary electrophoresis method with a 96% confidence level.


Subject(s)
Conductometry/instrumentation , Copper/chemistry , Dipeptides/analysis , Food Analysis/instrumentation , Metal Nanoparticles/chemistry , Nanotubes, Carbon/chemistry , Electrodes , Food Additives/analysis , Metal Nanoparticles/ultrastructure , Nanotubes, Carbon/ultrastructure , Reproducibility of Results , Sensitivity and Specificity , Sweetening Agents/analysis
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