Mani Govindasamy
Ming chi University of Technology, Materials Engineering, Faculty Member
- National Taipei University of Technology, EOMP, Department MemberNational Taipei University of Technology, Department of Materials and Mineral Resources Engineering, Faculty Memberadd
Potentially hazardous chemical contaminants endanger the environment and human well-being, challenging scientists and policy makers to develop holistic alternative approaches for remediation.
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In this work, stable and catalytically active copper ferrite nanodots (CuFe2O4) entrapped by porous RGO nanosheets were prepared via a facile condensation process using a green reducing agent.
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A trace level electrochemical detection platform for the determination of environmentally hazardous pollutant 4-aminophenol at MoS2nanoclusters is reported.
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AbstractWe describe a hybrid material that consists of molybdenum sulfide flowers placed on graphene nanosheets and multiwalled carbon nanotubes (GNS-CNTs/MoS2). It was deposited on a glassy carbon electrode (GCE) which then is well... more
AbstractWe describe a hybrid material that consists of molybdenum sulfide flowers placed on graphene nanosheets and multiwalled carbon nanotubes (GNS-CNTs/MoS2). It was deposited on a glassy carbon electrode (GCE) which then is well suited for sensitive and selective determination of dopamine. The GNS-CNTs/MoS2 nanocomposite was prepared by a hydrothermal method and characterized by scanning electron and transmission emission microscopies, energy-dispersive X-ray spectroscopy, cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy. Electrochemical studies show the composite to possess excellent electrochemical properties such as a large electrochemically active surface, high capacitance current, a wide potential window, high conductivity and large porosity. The electrode displays excellent electrocatalytic ability to oxidize dopamine. The modified GCE, best operated at a working potential as low as 0.15 V (vs. Ag/AgCl), responds linearly to dopamine in the 100 nM to 100 μM concentration range. The detection limit is 50 nM, and the sensitivity is 10.81 (± 0.26) μA⋅μM−1⋅cm−2. The sensor has good selectivity, appreciable stability, repeatability and reproducibility. It was applied to the determination of dopamine in (spiked) biological and pharmaceutical samples. Graphical abstractA sensitive and selective dopamine sensor was developed using molybdenum disulfide flowers decorated graphene and multiwalled carbon nanotubes composite. The linear range of the sensor is from 100 nM to 100 μM, and detection limit is 50 nM
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Electrodeposition of gold nanoparticles on a pectin scaffold for the selective determination of dopamine.
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We describe a hybrid material that consists of mo-lybdenum sulfide flowers placed on graphene nanosheets and multiwalled carbon nanotubes (GNS-CNTs/MoS 2). It was deposited on a glassy carbon electrode (GCE) which then is well suited for... more
We describe a hybrid material that consists of mo-lybdenum sulfide flowers placed on graphene nanosheets and multiwalled carbon nanotubes (GNS-CNTs/MoS 2). It was deposited on a glassy carbon electrode (GCE) which then is well suited for sensitive and selective determination of dopamine. The GNS-CNTs/MoS 2 nanocomposite was prepared by a hydrothermal method and characterized by scanning electron and transmission emission microscopies, energy-dispersive X-ray spectroscopy, cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spec-troscopy. Electrochemical studies show the composite to possess excellent electrochemical properties such as a large electrochemically active surface, high capacitance current, a wide potential window, high conductivity and large porosity. The electrode displays excellent electrocatalytic ability to oxidize dopamine. The modified GCE, best operated at a working potential as low as 0.15 V (vs. Ag/AgCl), responds linearly to dopamine in the 100 nM to 100 μM concentration range. The detection limit is 50 nM, and the sensitivity is 10.81 (± 0.26) μA⋅μM −1 ⋅cm −2. The sensor has good selectivity, appreciable stability, repeatability and reproducibility. It was applied to the determination of dopamine in (spiked) biological and pharmaceutical samples.
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A simple and rapid green synthesis using Bischofia javanica Blume leaves as reducing agent was developed for the preparation of gold nanoparticles (AuNPs). AuNPs decorated graphene oxide (AuNPs/GO) was prepared and employed for the... more
A simple and rapid green synthesis using Bischofia javanica Blume leaves as reducing
agent was developed for the preparation of gold nanoparticles (AuNPs). AuNPs decorated
graphene oxide (AuNPs/GO) was prepared and employed for the sensitive amperometric
determination of chloramphenicol. The green biosynthesis requires less than 40 s to reduce gold
salts to AuNPs. The formations of AuNPs and AuNPs/GO were evaluated by scanning electron
and atomic force microscopies, UV-Visible and energy dispersive X-ray spectroscopies, X-ray
diffraction studies, and electrochemical methods. AuNPs/GO composite film modified electrode
was fabricated which shown excellent electrocatalytic ability towards chloramphenicol. Under
optimal conditions, the amperometric sensing platform has delivered wide linear range of 1.5
μM–2.95 μM, low detection limit of 0.25 μM and high sensitivity of 3.81 μAμM–1 cm-2. The
developed sensor exhibited good repeatability and reproducibility, anti-interference ability and
long-term storage stability. Practical feasibility of the sensor has been demonstrated in food
samples (milk, powdered milk and honey) and pharmaceutical sample (eye drops). The green
synthesized AuNPs/GO composite has great potential for analysis of food samples in food safety
measures.
Keywords: Green synthesis, metal nanoparticles, plant extracts, graphene oxide,
chloramphenicol, antibiotics, food safety, milk, eye drops, modified electrode
agent was developed for the preparation of gold nanoparticles (AuNPs). AuNPs decorated
graphene oxide (AuNPs/GO) was prepared and employed for the sensitive amperometric
determination of chloramphenicol. The green biosynthesis requires less than 40 s to reduce gold
salts to AuNPs. The formations of AuNPs and AuNPs/GO were evaluated by scanning electron
and atomic force microscopies, UV-Visible and energy dispersive X-ray spectroscopies, X-ray
diffraction studies, and electrochemical methods. AuNPs/GO composite film modified electrode
was fabricated which shown excellent electrocatalytic ability towards chloramphenicol. Under
optimal conditions, the amperometric sensing platform has delivered wide linear range of 1.5
μM–2.95 μM, low detection limit of 0.25 μM and high sensitivity of 3.81 μAμM–1 cm-2. The
developed sensor exhibited good repeatability and reproducibility, anti-interference ability and
long-term storage stability. Practical feasibility of the sensor has been demonstrated in food
samples (milk, powdered milk and honey) and pharmaceutical sample (eye drops). The green
synthesized AuNPs/GO composite has great potential for analysis of food samples in food safety
measures.
Keywords: Green synthesis, metal nanoparticles, plant extracts, graphene oxide,
chloramphenicol, antibiotics, food safety, milk, eye drops, modified electrode
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Herein, we have demonstrated a new electrochemical sensor for trace level detection of environmentally hazardous 4-aminophenol (4-AP) using a glassy carbon electrode (GCE) modified with MoS 2 nanoclusters. The MoS 2 nanoclusters were... more
Herein, we have demonstrated a new electrochemical sensor for trace level detection of environmentally hazardous 4-aminophenol (4-AP) using a glassy carbon electrode (GCE) modified with MoS 2 nanoclusters. The MoS 2 nanoclusters were fabricated by a simple hydrothermal treatment without using any other organic templates or surfactants. The formation of MoS 2 nanoclusters was confirmed by X-ray diffraction, FT-infrared, Raman and energy dispersive X-ray spectroscopies, scanning electron and transmission electron microscopies and selected area electron diffraction studies. The MoS 2 modified GCE (MoS 2 /GCE) shows good electrocatalytic activity towards the redox reaction of 4-AP by means of cyclic voltammetry and differential pulse voltammetry. The DPV detection of 4-AP using MoS 2 /GCE delivers excellent sensitivity with a low detection limit of 0.03 (AE0.008) mM and good linearity in the range of 0.04–17 mM. The sensitivity of the developed electrode is 4.278 (AE0.058) mA mM À1 cm À2. The developed sensor displayed good repeatability, reproducibility and selectivity. Moreover, the practical applicability of the MoS 2 /GCE is demonstrated in water samples which delivered satisfactory recoveries.
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Abstract: We described the use of a nanocomposite consisting of reduced graphene oxide and zinc tetraphenylporphyrin (RGO/Zn-TPP) for electrochemical sensing of dopamine (DA). The surface of RGO was homogeneously functionalized with... more
Abstract: We described the use of a nanocomposite consisting
of reduced graphene oxide and zinc tetraphenylporphyrin
(RGO/Zn-TPP) for electrochemical sensing of
dopamine (DA). The surface of RGO was homogeneously
functionalized with Zn-TPP via non-covalent p-p interaction.
The nanocomposite was characterized by scanning
electron microscopy, UV-Vis spectrometry, nuclear magnetic
resonance spectroscopy and electrochemical impedance
spectroscopy. The electroanalysis behavior of the
nanocomposite was studied by cyclic voltammetry and
amperometry. The excellent electrocatalytic activity is
found for oxidation of DA, best at working voltage of
0.214 V (vs. Ag/AgCl) and linear response range of 0.04–
238.8 mM. The sensitivity and detection limit were of
0.665 mAmM1cm2 and 3 nM, respectrively. The electrode
is well reproducible, stable, and represents a viable
platform for the analysis of DA in DA injection, human
serum and rat brain sample.
Keywords: Electrocatalysis · Dopamine · Human serum · Rat brain sample · Dopamine hydrochloride injection
of reduced graphene oxide and zinc tetraphenylporphyrin
(RGO/Zn-TPP) for electrochemical sensing of
dopamine (DA). The surface of RGO was homogeneously
functionalized with Zn-TPP via non-covalent p-p interaction.
The nanocomposite was characterized by scanning
electron microscopy, UV-Vis spectrometry, nuclear magnetic
resonance spectroscopy and electrochemical impedance
spectroscopy. The electroanalysis behavior of the
nanocomposite was studied by cyclic voltammetry and
amperometry. The excellent electrocatalytic activity is
found for oxidation of DA, best at working voltage of
0.214 V (vs. Ag/AgCl) and linear response range of 0.04–
238.8 mM. The sensitivity and detection limit were of
0.665 mAmM1cm2 and 3 nM, respectrively. The electrode
is well reproducible, stable, and represents a viable
platform for the analysis of DA in DA injection, human
serum and rat brain sample.
Keywords: Electrocatalysis · Dopamine · Human serum · Rat brain sample · Dopamine hydrochloride injection
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Flower-like MoS2 nanostructure was grown on graphene and carbon nanotubes (GR-MWCNTs) via insitu hydrothermal method and the resulting composite was employed for determination of hydrogen peroxide (H2O2). The MoS2/GR-MWCNTs composite was... more
Flower-like MoS2 nanostructure was grown on graphene and carbon nanotubes (GR-MWCNTs) via insitu hydrothermal method and the resulting composite was employed for determination of hydrogen peroxide (H2O2). The MoS2/GR-MWCNTs composite was characterized by scanning electron microscopy, Energy-dispersive X-ray spectroscopy and electrochemical methods. MoS2/GRMWCNTs possess three dimensional nanostructure, large electrochemically active surface area, porosity, and high conductivity and it was used for the enzymeless electrochemical determination of hydrogen peroxide. MoS2/GR-MWCNTs composite film modified electrode showed excellent electrocatalytic ability to the reduction of H2O2. The composite delivered significantly improved electrocatalytic ability to H2O2 in comparison with control electrodes. Furthermore, the electrode exhibited low overpotential, high faradaic current and fast response time. MoS2/GR-MWCNTs composite film modified electrode responds quickly to H2O2 over wide working concentration range of 5 µM–145 µM, sensitivity of 5.184 µAµM cm-2 and detection limit of 0.83 µM. Moreover, the sensor exhibited appreciable stability, repeatability and reproducibility. Real-time application was demonstrated in biological sample which showed good recoveries. The other advantages of the fabricated biosensor are simple and green fabrication approach, roughed and stable electrode surface, fast in sensing and highly reproducible, good biocompatibility, electrocatalytic ability and excellent
synergy between MoS2, MWCNTs and GR.
synergy between MoS2, MWCNTs and GR.
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We have prepared graphene-bismuth nanoparticle (Bi) nanocomposite by simple solution based chemical reduction method and explored its biosensor application for the enzymatic determination of glucose. The characterization results revealed... more
We have prepared graphene-bismuth nanoparticle (Bi) nanocomposite by simple solution based chemical reduction method and explored its biosensor application for the enzymatic determination of glucose. The characterization results revealed the successful formation of the composite. The graphene-Bi nanocomposite was used for the immobilization of glucose oxidase (GOx). Direct electron transfer of GOx was observed with well-defined redox peaks at the formal potential of – 0.427 V. The amount of electroactive GOx (Г) and electron transfer rate constant (k s) were calculated to be 5.48×10-10 mol cm-2 and 5.57 s-1 , respectively. An amperometric glucose biosensor has been fabricated which detects glucose in a wide linear range from 1 mM to 12 mM with high sensitivity (2.243 µAmM-1 cm-2). Practical feasibility of the biosensor is explored in human blood serum sample which are revealed the excellent practicality of the biosensor. Moreover, the sensor exhibited appreciable stability, repeatability and reproducibility.
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A simple electrochemical deposition strategy is proposed for the preparation of gold nanoparticles (Au NPs) at the electrode surface using biopolymer pectin as stabilizing agent. The formation of the nanoparticles was confirmed by... more
A simple electrochemical deposition strategy is proposed for the preparation of gold nanoparticles (Au NPs) at the electrode surface using biopolymer pectin as stabilizing agent. The formation of the nanoparticles was confirmed by scanning electron microscopy (SEM), UV-visible spectroscopy and X-ray diffraction (XRD) studies. A pectin-stabilized, gold nanoparticle film-modified glassy carbon electrode (pectin–Au NP/GCE) was prepared, which exhibited excellent electrocatalytic ability towards oxidation of dopamine (DA). At the pectin–Au NP/GCE, the redox couple corresponding to the redox reaction of DA was observed at the formal potential of 0.20 V with highly enhanced peak currents. A thin layer of nafion coating was applied on the pectin–Au NP composite to improve its selectivity. Two linear ranges of detection were found: (1) 20 nM to 0.9 mM with a limit of detection (LOD) of 6.1 nM, (2) 0.9 mM to 1 mM with a LOD of 0.64 mM. The fabricated sensor selectively detects DA even in the presence of high concentrations of interferents. Moreover, practical feasibility of the sensor was addressed in pharmaceutical samples, which presented appreciable recovery results. The main advantages of the sensor are its very simple and green fabrication approach, roughed and stable structure, and fast and highly reproducible detection of dopamine.