Nanocatalysts based on Ag and AuNPs stabilized over chitosan functionalized GO exhibited excellent catalytic activity towards reduction of nitroarenes and dye degradation.

Rajesh R

Department of Communication Engineering

School of Electronics Engineering

Vellore Campus

Senthil Kumar S

Department of Design and Automation

School of Mechanical Engineering

Senthilkumar S

Department of Chemistry

School of Advanced Sciences

Sujanthi E

Venkatesan R.

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

&nbsp;

&nbsp;

VIT University

Physical Chemistry Chemical Physics

Design and development of electrochemical biosensors with improved selectivity, sensitivity and stability is one of the thrust areas of research in analytical and materials chemistry. In the present work, hemoglobin (Hb) was covalently immobilized on polyamidoamine (PAMAM) dendrimer encapsulated with gold nanoparticles (AuNPs), which was further utilized for the electrochemical detection of hydrogen peroxide (H2O2). Third generation PAMAM dendrimers were synthesized and AuNPs were encapsulated within the dendrimer network. Hb was covalently immobilized through glutaraldehyde cross-linking between the free amino groups of Hb and that of the PAMAM dendrimer. Hb/PAMAM-AuNPs was immobilized on a glassy carbon electrode (GCE) and the Hb/PAMAM-AuNPs/GCE modified electrode thus fabricated was characterized with electrochemical impedance spectroscopy and cyclic voltammetry. The Hb/PAMAM-AuNPs/GCE biosensor displayed well resolved redox peaks with anodic peak potential at −0.252 V and cathodic potential at −0.321 V, corresponding to Fe(III)/Fe(II) redox couple of heme active centre. Further, the developed Hb/PAMAM-AuNPs/GCE showed very good electrocatalytic activity for the reduction of H2O2 at a potential of −0.35 V. The Hb/PAMAM-AuNPs/GCE biosensor has shown impressive performance towards H2O2 determination in the concentration range from 20 μM to 950.22 μM. The sensitivity of the biosensor was calculated to be 35.07 μA μM−1 cm−2 with a detection limit of 6.1 μM. Also, the Hb/PAMAM-AuNPs/GCE modified electrode exhibited higher stability and good reproducibility. © 2019 Elsevier B.V.

Applied Surface Science

Covalent immobilization and enhanced electrical wiring of hemoglobin using gold nanoparticles encapsulated PAMAM dendrimer for electrochemical sensing of hydrogen peroxide

Abstract: Green synthesis of metal nanoparticles using earth abundant materials in the absence of any toxic solvent, reducing agent and protecting group is one of the emerging areas of research in materials chemistry. Herein, we report a green method for the synthesis of silver nanoparticles (AgNPs) using Actinodaphne madraspatana Bedd leaf extract as reducing as well as stabilizing agent. To our delight, AgNPs of different sizes could be readily synthesized by simply changing the pH of plant extract and the average size of AgNPs were found to be 60, 35 and 20 nm at pH 6, 9 and 12 respectively. The efficacy of prepared AgNPs towards the catalytic reduction of 4-nitrophenol (4-NP) has been investigated and the nanocatalysts have demonstrated excellent catalytic activity as evidenced from the rate constants. The kinetics of reduction reaction follows Langmuir–Hinshelwood mechanism, based on which the rate constant ‘k’ was calculated. The effect of catalyst dosage, concentration of 4-NP, concentration of NaBH4 and size of AgNPs towards catalytic reduction of 4-NP has been systematically investigated. It was interesting to notice that the AgNPs have exhibited size dependent catalytic activity towards reduction of 4-NP and the catalytic activity was found to increase with decrease in particle size. Graphical Abstract: [Figure not available: see fulltext.]. © 2017, Springer Science+Business Media New York.

Journal of Cluster Science

Size Dependent Catalytic Activity of Actinodaphne madraspatana Bedd Leaves Mediated Silver Nanoparticles

The authors report on a nonenzymatic catechol sensor that is based on the immobilization of ferrocene (Fc) on graphene oxide (GO). A glassy carbon electrode (GCE) was modified with GO which then was silanized with (3-aminopropyl)trimethoxysilane. Ferrocenecarboxaldehyde was then immobilized on GO via formation of a Schiff base. The immobilization process was monitored stepwise by using FTIR spectroscopy, X-ray diffraction, cyclic voltammetry (CV) and electrochemical impedance spectroscopy. Investigation of the modified electrode by CV revealed a pair of well-defined redox peaks with anodic and cathodic peak potentials at +0.380 and +0.277 V, corresponding to the Fc/Fc+ redox couple. The Fc modified electrode exhibits excellent electrocatalytic activity towards the oxidation of catechol at a typical working voltage of +0.45 V (vs. Ag/AgCl). The response is linear in the 3 to 112 μM catechol concentration range, the detection limit is 1.1 μM, and the sensitivity is 1184.3 μA·mM−1·cm−2. The sensor is stable, reproducible and reasonably selective. It was successfully applied to the determination of catechol in spiked tap water and lake water samples. [Figure not available: see fulltext.]. © 2017, Springer-Verlag Wien.

Microchimica Acta

Amperometric sensing of catechol using a glassy carbon electrode modified with ferrocene covalently immobilized on graphene oxide

Herein, we report the stabilization of silver and gold nanoparticles (Ag/Au NPs) on graphene oxide (GO) functionalized with PAMAM dendrimers. The grafting of the PAMAM dendrimers on GO has been investigated using TGA and Raman spectral studies and the stabilization of the Ag/Au NPs on the dendritic structures has been confirmed using XRD, UV-Vis and FT-IR spectra, SEM and TEM studies. The catalytic activity of the prepared nanocatalysts towards the degradation of organic azo dyes, namely methyl orange and congo red, has been tested. The prepared nanocatalysts were found to exhibit excellent catalytic activity towards the complete degradation of both methyl orange and congo red within only a few seconds. © 2014 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

New Journal of Chemistry

Efficient degradation of azo dyes using Ag and Au nanoparticles stabilized on graphene oxide functionalized with PAMAM dendrimers

Catalysis Communications

Transition metal nanoparticles supported on mesoporous polyaniline catalyzed reduction of nitroaromatics

Graphene oxide-P25 photocatalysts for degradation of diphenhydramine pharmaceutical and methyl orange dye

Journal of Nanoparticle Research

Efficient adsorption and photocatalytic degradation of Congo red onto hydrothermally synthesized NiS nanoparticles

Methods in Molecular Biology Nucleic Acid Detection

Graphene–PAMAM Dendrimer–Gold Nanoparticle Composite for Electrochemical DNA Hybridization Detection

Designing versatile heterogeneous catalysts based on Ag and Au nanoparticles decorated on chitosan functionalized graphene oxide

Journal	Data powered by TypesetPhysical Chemistry Chemical Physics
Publisher	Data powered by TypesetRoyal Society of Chemistry (RSC)
ISSN	1463-9076
Open Access	0