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.

Senthilkumar S

Department of Chemistry

School of Advanced Sciences

Vellore Campus

Elancheziyan M

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

Applied Surface Science

An aldehyde functionalized ionic liquid, (3-(3-formyl-4-hydroxybenzyl)-3-methylimidazolium hexafluorophosphate) (CHO-IL) has been employed herein as a multiple host platform for the covalent immobilization of mediator as well as enzyme. The CHO-IL was immobilized on electrochemically reduced graphene oxide (ERGO) through the π-π stacking of hydroxybenzyl and imidazolium groups with ERGO and subjected to further covalent attachment of Azure A (Azu-A) mediator or glucose oxidase (GOx) enzyme. Electroactive, water soluble organic dye Azu-A was effectively immobilized to the host IL through simple Schiff base reaction. Azu-A was rendered leak-free in the electrode setup and also responded well for the amperometric determination of H2O2 over a linear range of 0.03–1 mM with a detection limit and sensitivity of 11.5 µM and 133.2 µA mM−1 cm−2, respectively. Further, attempts were made to explore the CHO-IL platform for the covalent immobilization of GOx enzyme which served well in retaining the enzyme nativity, reactivity and stability. Under optimized conditions, mediatorless GOx biosensor developed based on direct electrochemistry has exhibited an impressive analytical signal towards glucose detection in the linear range of 0.05–2.4 mM with a detection limit and sensitivity of 17 µM and 17.7 µA mM−1 cm−2, respectively. The reliability of the proposed Azu-A based chemical sensor and GOx based biosensor towards the determination of H2O2 and glucose in the real samples have been demonstrated. The remarkable analytical parameters and long term stability of both the sensors could be envisioned as a result of facile immobilization platform and immobilization strategy. © 2017 Elsevier B.V.

Biosensors and Bioelectronics

Aldehyde functionalized ionic liquid on electrochemically reduced graphene oxide as a versatile platform for covalent immobilization of biomolecules and biosensing

The enzyme horseradish peroxidase and the water-soluble mediator toluidine blue were covalently immobilized to 3-aminopropyl trimethoxy silane precursor through glutaraldehyde crosslinker. A rigid ceramic composite electrode was fabricated from this modified silane along with graphite powder, which resulted in an amperometric biosensor for H2O2. The electrochemical behaviour of the modified biosensor was monitored using cyclic voltammetry in the potential range of 0.2 V to − 0.4 V vs SCE. The biosensor exhibited a stable voltammogram with cathodic peak at − 0.234 V and anodic peak at − 0.172 V, with a formal potential of − 0.203 V. Various factors influencing the performance of the biosensor such as buffer solution, pH, temperature and potential were examined for optimizing the working conditions. The modified biosensor exhibited a good catalytic behaviour for the reduction of H2O2 at a lower potential of − 0.25 V without any barrier from possible interferents. The analytical working range was found to be 0.429 μM to 0.455 mM of H2O2 with a detection limit of 0.171 μM. The fabricated biosensor is robust for long-term usage in addition to the high sensitivity, rapid response and having an advantage of surface renewability by simple mechanical polishing. © 2016 Elsevier B.V.

Materials Science and Engineering: C

Horseradish peroxidase and toluidine blue covalently immobilized leak-free sol-gel composite biosensor for hydrogen peroxide

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

Physical Chemistry Chemical Physics

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

Ionic liquids are room-temperature molten salts that are increasingly used in electrochemical devices, such as batteries, fuel cells, and sensors, where their intrinsic ionic conductivity is exploited. Here we demonstrate that combining anionic, redox-active Au25 clusters with imidazolium cations leads to a stable ionic liquid possessing both ionic and electronic conductivity. The Au25 ionic liquid was found to act as a versatile matrix for amperometric enzyme biosensors toward the detection of glucose. Enzyme electrodes prepared by incorporating glucose oxidase in the Au25 ionic liquid show high electrocatalytic activity and substrate affinity. Au25 clusters in the electrode were found to act as effective redox mediators as well as electronic conductors determining the detection sensitivity. With the unique electrochemical properties and almost unlimited structural tunability, the ionic liquids of quantum-sized gold clusters may serve as versatile matrices for a variety of electrochemical biosensors.

ACS Nano

Ionic Liquid of a Gold Nanocluster: A Versatile Matrix for Electrochemical Biosensors

Journal of Solid State Electrochemistry

Pt–Ru nanoparticles supported PAMAM dendrimer functionalized carbon nanofiber composite catalysts and their application to methanol oxidation

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

Journal	Data powered by TypesetApplied Surface Science
Publisher	Data powered by TypesetElsevier BV
ISSN	0169-4332
Open Access	0