Electrochemical Ultra-Low Detection of Isoniazid Using a Salicylaldamine Functionalised G1-DAB-(NH2)4 Dendritic Sensor vs. UV-VIS Spectrophotometric Detection

2017 ◽  
Vol 45 ◽  
pp. 164-174
Author(s):  
Candice Rassie ◽  
Juanita Van Wyk ◽  
Lindsay Wilson ◽  
Nomaphelo Ntshongontshi ◽  
Anovuyo Jonnas ◽  
...  
Keyword(s):  
Electrochemical Detection ◽  
Limit Of Detection ◽  
Dendritic Structure ◽  
Spectroscopy Method ◽  
Routine Laboratory ◽  
Visible Spectroscopy ◽  
First Line ◽  
Spectrophotometric Detection ◽  
Sem Images ◽  
Copper Centre

A poly(propyleneimine) based dendrimer was synthesised and successfully functionalised with a copper centre within its branches. The dendrimer and corresponding metallodendrimer were successfully characterised using FTIR, HR-TEM and HR-SEM in order to determine the effect of the inclusion of copper into the dendritic structure. The incorporation of copper caused crystallinity as revealed in the HR-TEM and a sheet-like morphology as shown in the HR-SEM images. The resulting metallodendrimer was then applied as an electrocatalytic platform for the sensing of a first line TB drug called isoniazid. This method was compared to a routine laboratory detection using UV-Vis and was found to be much more sensitive to trace amounts of isoniazid in solution. The electrochemical detection was found to have a limit of detection (LOD) of 0.233 nM compared to 11.47 nM using the Ultraviolet-visible spectroscopy method.

Graphene Oxide as a Substrate for Biosensors: Synthesis and Characterization

2021 ◽  
Vol 324 ◽  
pp. 87-93
Author(s):  
Mohamed Adel ◽  
Abdel Hady A. Abdel-Wahab ◽  
Ahmed Abdel-Mawgood ◽  
Ahmed Osman Egiza
Keyword(s):  
Raman Spectroscopy ◽  
Graphene Oxide ◽  
Acidic Solution ◽  
Cost Effective ◽  
Sem Analysis ◽  
Visible Spectroscopy ◽  
Sem Images ◽  
Hummers Method ◽  
Uv Visible ◽  
Modified Hummers Method

Graphene oxide (GO) is an oxidized nanosheets of graphite with a 2D planar structure. GO could be readily complexed with bio-entities as it possesses many oxygen-containing functionalities on its surface. The preparation process is fast, easy, and cost-effective. It was prepared using modified Hummers’ method in acidic solution as a primary solvent and potassium permanganate as an oxidizing agent. Afterwards, it was successfully characterized by FTIR, UV-visible spectroscopy, as well as XRD and Raman spectroscopy, and finally, SEM analysis. It was observed that the formed GO is mainly composed of carbon and oxygen elements rich in oxygen functional groups. Furthermore, the existence of (001) plane in XRD interprets the complete oxidation of graphite with d-spacing 9 Å. Moreover, Raman spectroscopy displayed the sp3 carbon hybridization, besides, the ID/IG ratio is found to be 0.84, which confirms the disorder between graphene oxide layers. The SEM images also pointed out that graphene oxide sheets were regularly stacked together as flake-like structures. Accordingly, the richness of oxygen-containing functionalities was confirmed. Hence, it is appropriate to be used as a base transducer for biosensing applications.

scholarly journals TEMPO-Functionalized Nanoporous Au Nanocomposite for the Electrochemical Detection of H2O2

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Dongxiao Wen ◽  
Qianrui Liu ◽  
Ying Cui ◽  
Huaixia Yang ◽  
Jinming Kong
Keyword(s):  
Electrochemical Detection ◽  
Nanoporous Gold ◽  
Carboxyl Groups ◽  
Time Interval ◽  
Optimal Conditions ◽  
Sem Images ◽  
One Step ◽  
Ph Range ◽  
Synthesis Approach ◽  
Higher Sensitivity

A novel nanocomposite of nanoporous gold nanoparticles (np-AuNPs) functionalized with 2,2,6,6-tetramethyl-1-piperidinyloxy radical (TEMPO) was prepared; assembled carboxyl groups on gold nanoporous nanoparticles surface were combined with TEMPO by the “bridge” of carboxylate-zirconium-carboxylate chemistry. SEM images and UV-Vis spectroscopies of np-AuNPs indicated that a safe, sustainable, and simplified one-step dealloying synthesis approach is successful. The TEMPO-np-AuNPs exhibited a good performance for the electrochemical detection of H2O2 due to its higher number of electrochemical activity sites and surface area of 7.49 m2g-1 for load bigger amount of TEMPO radicals. The TEMPO-functionalized np-AuNPs have a broad pH range and shorter response time for H2O2 catalysis verified by the response of amperometric signal under different pH and time interval. A wide linear range with a detection limit of 7.8 × 10-7 M and a higher sensitivity of 110.403 μA mM-1cm-2 were obtained for detecting H2O2 at optimal conditions.

scholarly journals Development of Pd/TiO2 Porous Layers by Pulsed Laser Deposition for Surface Acoustic Wave H2 Gas Sensor

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 760 ◽  
Author(s):  
Izabela Constantinoiu ◽  
Cristian Viespe
Keyword(s):  
Acoustic Wave ◽  
Frequency Shift ◽  
Pulsed Laser Deposition ◽  
Surface Acoustic Wave ◽  
Limit Of Detection ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
High Porosity ◽  
Porous Films ◽  
Sem Images

The influence of sensitive porous films obtained by pulsed laser deposition (PLD) on the response of surface acoustic wave (SAW) sensors on hydrogen at room temperature (RT) was studied. Monolayer films of TiO2 and bilayer films of Pd/TiO2 were deposited on the quartz substrates of SAW sensors. By varying the oxygen and argon pressure in the PLD deposition chamber, different morphologies of the sensitive films were obtained, which were analyzed based on scanning electron microscopy (SEM) images. SAW sensors were realized with different porosity degrees, and these were tested at different hydrogen concentrations. It has been confirmed that the high porosity of the film and the bilayer structure leads to a higher frequency shift and allow the possibility to make tests at lower concentrations. Thus, the best sensor, Pd-1500/TiO2-600, with the deposition pressure of 600 mTorr for TiO2 and 1500 mTorr for Pd, had a frequency shift of 1.8 kHz at 2% hydrogen concentration, a sensitivity of 0.10 Hz/ppm and a limit of detection (LOD) of 1210 ppm. SAW sensors based on such porous films allow the detection of hydrogen but also of other gases at RT, and by PLD method such sensitive porous and nanostructured films can be easily developed.

scholarly journals Preconcentration of morphine in urine sample using a green and solvent-free microextraction method

2019 ◽  
Vol 8 (1) ◽  
pp. 542-550
Author(s):  
Bamdad Riahi-Zanjani ◽  
Mahdi Balali-Mood ◽  
Zarrin Es’haghi ◽  
Ahmad Asoodeh ◽  
Adel Ghorani-Azam
Keyword(s):  
Urine Sample ◽  
Small Volume ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Medical Toxicology ◽  
Significant Loss ◽  
Solvent Free ◽  
Environmental Damage ◽  
Limit Of Quantification ◽  
Sem Images

Abstract The ability of extraction and preconcentration of small amounts of substances from biological samples is very important in medical toxicology. On the other hand, minimal use of organic solvents is an important issue to prevent environmental damage. In the present study, we developed a new solid phase microextraction fiber using plant extracts as sorbent for extraction and preconcentration of morphine in urine sample. For this purpose, raw carbon nanotubes (CNTs) were functionalized with tobacco extracts. Functionalization was confirmed by Fourier transform infrared (FTIR) and Raman spectroscopy in addition to scanning electron microscope (SEM) images. The functionalized CNTs were coated on polypropylene hollow fiber. The results of HPLC analysis showed that the produced fiber could preconcentrate a very low concentration of morphine (0.25 ng/ml) in small volume of urine samples. Limit of detection (LOD) and limit of quantification (LOQ) for the produced fiber were determined 0.25 ng/ml and 0.825 ng/ml, respectively, and recovery of the fiber was determined 89% at LOQ. The produced fiber provided a recyclable and solvent free method for extraction of a trace amount of morphine, which can be successfully used for up to 30 times with no significant loss in the extraction efficiency.

scholarly journals Dendritic Structure Analysis of CMSX-4 Cored Turbine Blades Roots

2016 ◽  
Vol 61 (2) ◽  
pp. 1129-1134 ◽  
Author(s):  
J. Krawczyk
Keyword(s):  
Single Crystal ◽  
Cross Sections ◽  
Induction Furnace ◽  
Turbine Blades ◽  
Dendritic Structure ◽  
Root Structure ◽  
Sem Images ◽  
X Ray ◽  
Nickel Based Superalloy

Abstract The microstructure of as-cast cored turbine blades roots, made of the single-crystal CMSX-4 nickel-based superalloy was investigated. Analysed blades were obtained by directional solidification technique in the industrial ALD Bridgman induction furnace. The investigations of the microstructure of blades roots were performed using SEM and X-ray techniques including diffraction topography with the use of Auleytner method. Characteristic shapes of dendrites with various arrangement were observed on the SEM images taken from the cross-sections, made transversely to the main blades axis. The differences in quality of the structure in particular areas of blades roots were revealed. Based on the results, the influence of cooling bores on blades root structure was analysed and the changes in the distribution and geometry of cooling bores were proposed.

scholarly journals Optimization and Application of Electrochemical Transducer for Detection of Specific Oligonucleotide Sequence for Mycobacterium tuberculosis

Biosensors ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 84 ◽  
Author(s):  
Ricardo Corrêa ◽  
Filipe da Cruz ◽  
Cátia Santos ◽  
Thiago Pimenta ◽  
Diego Franco ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Mycobacterium Tuberculosis ◽  
Limit Of Detection ◽  
Polymeric Film ◽  
Adsorption Parameters ◽  
Limit Of Quantification ◽  
Sem Images ◽  
Complementary Oligonucleotide ◽  
Scan Rate ◽  
Oligonucleotide Sequence

In this study, the electropolymerization of 4-hydroxyphenylacetic acid (4-HPA) over graphite electrodes (GE) was optimized, aiming its application as a functionalized electrochemical platform for oligonucleotides immobilization. It was investigated for the number of potential cycles and the scan rate influence on the monomer electropolymerization by using cyclic voltammetry technique. It was observed that the polymeric film showed a redox response in the region of +0.53/+0.38 V and the increase in the number of cycles produces more electroactive platforms because of the better electrode coverage. On the other hand, the decrease of scan rate produces more electroactive platforms because of the occurrence of more organized coupling. Scanning electron microscopy (SEM) images showed that the number of potential cycles influences the coverage and morphology of the electrodeposited polymeric film. However, the images also showed that at different scan rates a more organized material was produced. The influence of these optimized polymerization parameters was evaluated both in the immobilization of specific oligonucleotides and in the detection of hybridization with complementary target. Poly(4-HPA)/GE platform has shown efficient and sensitive for oligonucleotides immobilization, as well as for a hybridization event with the complementary oligonucleotide in all investigated cases. The electrode was modified with 100 cycles at 75 mV/s presented the best responses in function of the amplitude at the monitored peak current values for the Methylene Blue and Ethidium Bromide intercalators. The construction of the genosensor to detect a specific oligonucleotide sequence for the Mycobacterium tuberculosis bacillus confirmed the results regarding the poly(4-HPA)/GE platform efficiency since it showed excellent sensitivity. The limit of detection and the limit of quantification was found to be 0.56 (±0.05) μM and 8.6 (±0.7) μM, respectively operating with very low solution volumes (15 µL of probe and 10 µL target). The biosensor development was possible with optimization of the probe adsorption parameters and target hybridization, which led to an improvement in the decrease of the Methylene Blue (MB) reduction signal from 14% to 34%. In addition, interference studies showed that the genosensor has satisfactory selectivity since the hybridization with a non-specific probe resulted in a signal decrease (46% lower) when compared to the specific target.

scholarly journals Recyclable SERS-Based Immunoassay Guided by Photocatalytic Performance of Fe3O4@TiO2@Au Nanocomposites

Biosensors ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 25 ◽  
Author(s):  
Yuanyuan Du ◽  
Hongmei Liu ◽  
Yiran Tian ◽  
Chenjie Gu ◽  
Ziqi Zhao ◽  
...  
Keyword(s):  
Photocatalytic Performance ◽  
Limit Of Detection ◽  
Specific Antigen ◽  
High Sensitivity ◽  
Shell Nanoparticles ◽  
Sem Images ◽  
Potential Measurement ◽  
Surface Enhanced Raman ◽  
Clinical Measurements ◽  
Core Shell Nanoparticles

A novel recyclable surface-enhanced Raman scattering (SERS)-based immunoassay was demonstrated and exhibited extremely high sensitivity toward prostate specific antigen (PSA). The immunoassay, which possessed a sandwich structure, was constructed of multifunctional Fe3O4@TiO2@Au nanocomposites as immune probe and Ag-coated sandpaper as immune substrate. First, by adjusting the density of outside Au seeds on Fe3O4@TiO2 core-shell nanoparticles (NPs), the structure-dependent SERS and photocatalytic performance of the samples was explored by monitoring and degradating 4-mercaptobenzonic acid (4MBA). Afterwards, the SERS enhancement capability of Ag-coated sandpaper with different meshes was investigated, and a limit of detection (LOD), as low as 0.014 mM, was achieved by utilizing the substrate. Subsequently, the recyclable feasibility of PSA detection was approved by zeta potential measurement, absorption spectra, and SEM images and, particularly, more than 80% of SERS intensity still existed after even six cycles of immunoassay. The ultralow LOD of the recyclable immunoassay was finally calculated to be 1.871 pg/mL. Therefore, the recyclable SERS-based immunoassay exhibits good application prospects for diagnosis of cancer in clinical measurements.

An atomically thick titanium phosphate thin layer with enhancing electrochemical sensitivity toward Pb(ii)

RSC Advances ◽  
2016 ◽  
Vol 6 (77) ◽  
pp. 72975-72984 ◽  
Author(s):  
Shan-Shan Li ◽  
Dong-Dong Han ◽  
Tian-Jia Jiang ◽  
Zheng Guo ◽  
Xing-Jiu Huang ◽  
...  
Keyword(s):  
Thin Layer ◽  
Electrochemical Detection ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Titanium Phosphate

An atomically thick titanium phosphate thin layer is synthesized and used for sensitive electrochemical detection for Pb(ii) with a high sensitivity and low limit of detection.

Determination of formaldehyde by flow injection analysis with spectrophotometric detection exploiting brilliant green–sulphite reaction

2015 ◽  
Vol 69 (6) ◽  
Author(s):  
Lúcio Bolognesi ◽  
Eder J. dos Santos ◽  
Gilberto Abate
Keyword(s):  
Flow Injection ◽  
Flow Injection Analysis ◽  
Brilliant Green ◽  
Limit Of Detection ◽  
Spectrophotometric Detection ◽  
Sample Throughput ◽  
First Time

AbstractA method for the determination of formaldehyde by flow injection analysis with spectrophotometric detection is proposed, based on retarding the reaction between brilliant green and sulphite by the addition of formaldehyde; this was investigated for formaldehyde quantification in extracts from wood-based panels. For the first time, a heating step was explored, providing a sample throughput of 50 analyses per hour, with a limit of detection of 0.02 mg L

scholarly journals Design, Development and Characterization of Graphene Sand Nano-Composite for Water Filtration

2020 ◽  
Vol 63 (2) ◽  
pp. 118-122
Author(s):  
Shahid Hussain Abro ◽  
Alidad Chandio ◽  
Iftikhar A. Channa ◽  
Abdulaziz S. Alaboodi
Keyword(s):  
Design Development ◽  
Visible Spectroscopy ◽  
Sem Images ◽  
River Sand ◽  
Nano Composite ◽  
Ftir Characterization ◽  
Global Issue ◽  
Scientific Approach ◽  
Uv Visible

  Water purification and filtration is a global issue and many researchers are engaged to resolve this problem by adopting the scientific approach, graphene sand composite was prepared through bio- synthesized technique. River sand was used in this context to remove the impurities already present in the sand 0.1M nitric acid treated the sand and the product was powder black in colour, referred as GSC, graphene sand composite. SEM, XRD and FTIR characterization was used to analyze the results. SEM images showed nano sized layers or sheets of graphene extending outwards.The XRD peak represents the multi lagered graphene structure which is formed by the treatment of the composite with acid and application of the high temperature during experiment UV-visible spectroscopy results successfully reveals the filtration difference between mud water and filtered water.  

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