The challenges of a heme protein and enzyme-based H2O2 sensor was subdued by developing a highly ... more The challenges of a heme protein and enzyme-based H2O2 sensor was subdued by developing a highly sensitive and practically functional amperometric gold nanoparticles (Au NPs)/SnO2 nanofibers (SnO2 NFs) composite sensor. The composite was prepared by mixing multiporous SnO2 NFs (diameter: 120–190 nm) with Au NPs (size: 3–5 nm). The synthesized Au NPs/SnO2 NFs composite was subsequently coated on a glassy carbon electrode (GCE) and displayed a well-defined reduction peak during a cyclic voltammetry (CV) analysis. The SnO2 NFs prevented the aggregation of Au NPs through its multiporous structure and enhanced the catalytic response by 1.6-fold. The SnO2 NFs-supported GCE/Au NPs/SnO2 NFs composite sensor demonstrated a very good catalytic activity during the reduction of hydrogen peroxide (H2O2) that displayed rapid amperometric behavior within 6.5 s. This sensor allowed for highly sensitive and selective detection. The sensitivity was 14.157 µA/mM, the linear detection range was from 49...
In this study, Titaium dioxide (TiO2) nanotubes (TNTs) were synthesized by a simple electrochemic... more In this study, Titaium dioxide (TiO2) nanotubes (TNTs) were synthesized by a simple electrochemical anodization method. TNTs were characterized by Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscope (TEM), UV-Vis Diffuse Reflectance Spectra and Photoluminescence (PL) Spectra to identify the morphology, crystalline phase and photocatalytic activity under the visible light. . The morphological analyses revealed that the inner diameter, and tube length of the synthesized TNTs has an average value of 60 nm, and 900 nm, respectively. The wall thickness of the TNTs is of 11 nm. Theobserved TNTs have nanotubular shape. The absorption edge in the visible range at around 400-460 nm obtained from UV-Vis Diffuse Reflectance Spectrum analysis. In addition, the PL spectral peak identified at around 400nm and 590 nm. The finding shows thatthe synthesized TNTs made by electrochemical anodization method has photocatalytic properties and can be used as a photocataly...
Biomedical Journal of Scientific & Technical Research, 2018
One of the most striking nanostructured materials is tin oxide (SnO 2) which has been used as nan... more One of the most striking nanostructured materials is tin oxide (SnO 2) which has been used as nanotubes, nanoparticles, nanowires, and nanorods [21,22]. Nanostructured SnO 2 possesses high surface area, nontoxicity, excellent biocompatibility, catalytic activity and chemical stability [23] which makes it suitable for various applications such as solar cells, electrochemistry, and biosensor [24-26]. We have fabricated a new one-dimensional nano-morphology of SnO 2 recently with the higher surface area and
A novel hydrogen peroxide biosensor has been designed based on the co-immobilization of hemoglobi... more A novel hydrogen peroxide biosensor has been designed based on the co-immobilization of hemoglobin (Hb), TiO 2 nanotubes and methylene blue (MB) onto a glassy carbon (GC) electrode. The titania nanotube arrays were directly grown on a Ti substrate using anodic oxidation first; and then detached from the Ti substrate using ultrasonication. A pair of well-defined redox peaks of Hb, enhanced by MB, appeared at an applied potential around À0.425 V, revealing that the immobilized Hb exhibits direct electrochemistry. Our electrochemical study shows that the immobilized Hb remains highly bioactive and displays excellent electrocatalytic response toward H 2 O 2. The effect of pH and applied electrode potential in H 2 O 2 sensing has been systemically studied. Besides the advantages of fast response and high stability, under the optimized conditions the linearity of the developed biosensor for the detection of H 2 O 2 was observed from 2 Â 10 À7 to 1.6 Â 10 À4 M with a detection limit as low as 8 Â 10 À8 M (based on S/N = 3).
A multiporous nanofiber (MPNFs) of SnO2 and chitosan has been used for the immobilization of a re... more A multiporous nanofiber (MPNFs) of SnO2 and chitosan has been used for the immobilization of a redox protein, hemoglobin (Hb), onto the surface of glassy carbon electrode (GCE). The multiporous nanofiber of SnO2 that has very high surface area is synthesized by using electrospinning technique through controlling the tin precursor concentration. Since the constructed MPNFs of SnO2 exposes very high surface area, it increases the efficiency for biomolecule-loading. The morphology of fabricated electrodes is examined by SEM observation and the absorbance spectra of Hb/(MPNFs) of SnO2 are studied by UV-Vis analysis. Cyclic Voltammetry and amperometry are employed to study and optimize the performance of the resulting fabricated electrode. After fabrication of the electrode with the Hb and MPNFs of SnO2, a direct electron transfer between the protein’s redox centre and the glassy carbon electrode was established. The modified electrode has showed a couple of redox peak located at -0.29 V...
The fabrication of a crosslinked network of glucose oxidase-horseradish peroxidase/tin oxide (GOx... more The fabrication of a crosslinked network of glucose oxidase-horseradish peroxidase/tin oxide (GOx-HRP/SnO2), immobilized on glassy carbon electrode (GCE) and its utilization as a sensor for glucose detection has been reported. The 3-D network established with GOx-HRP/SnO2 has possessed high sensitivity and stability by performing the electrocatalytic features in sensing of glucose. The turbidity of fabrication has been scanned and analyzed using UV-Vis Spectroscopy. The morphology and composition of the fabricated GOx-HRP modified multi-nanoporous SnO2 nanofibers were characterized by scanning electron microscopy (SEM). Cyclic voltammetry and amperometry were used to study the proposed electrochemical biosensor. The effect of applied electrode potential, pH and the concentration of glucose on the sensitivity of the biosensor have been systemically investigated which indicates that these systems should be very useful for other sensing applications
The fabrication of a network of glucose oxidase-horseradish peroxidase/tin oxide (GOx-HRP/SnO2), ... more The fabrication of a network of glucose oxidase-horseradish peroxidase/tin oxide (GOx-HRP/SnO2), immobilized onto a glassy carbon electrode (GCE) and its utilization as a biosensor for glucose detection is reported. The network established with GOx-HRP/SnO2 possess high sensitivity and stability by performing the electrocatalytic features in the sensing of glucose. The turbidity of fabrication had been scanned and analyzed using UV-vis spectroscopy. The morphology and composition of the fabricated GOx-HRP/SnO2 networks were characterized by scanning electron microscopy (SEM). Cyclic voltammetry and amperometry were employed to study the electrochemical properties of the proposed biosensor. The effect of applied electrode potential and pH were systemically investigated. The biosensor responds to glucose at work potential values between −400 mV, and exhibited a lower detection limit (0.025 mM) and long linear range (0.25 to 7.0 mM), and was resistant to common interferences.
In this work, we describe a new 3-dimensional (3D) network of crosslinked Horseradish Peroxidase/... more In this work, we describe a new 3-dimensional (3D) network of crosslinked Horseradish Peroxidase/Carbon Nanotube (HRP/CNT) on a thiol-modified Au surface in order to build up the effective electrical wiring of the enzyme units with the electrode. This is achieved by the electropolymerization of aniline-functionalized carbon nanotubes (CNTs) and 4-aminothiophenol -modified-HRP on a 4-aminothiophenol monolayer-modified Au electrode. The synthesized 3D HRP/CNT network has been characterized with cyclic voltammetry and amperometry, resulting the establishment direct electron transfer between the redox active unit of HRP and the Au surface. Electrochemical measurements reveal that the immobilized HRP exhibits high biological activity and stability and a quasi-reversible redox peak of the redox centre of HRP was observed at about −0.355 and −0.275 V vs. Ag/AgCl. The electron transfer rate constant, KS and electron transfer co-efficient are found to be 0.57 s-1 and 0.42, respectively. Base...
In this work, the direct electrochemistry of hemoglobin (Hb), which was immobilized on carbonyl f... more In this work, the direct electrochemistry of hemoglobin (Hb), which was immobilized on carbonyl functionalized single walled carbon nanotube (SWCNT) and deposited onto a gold (Au) electrode has been described. The synthesis of the network of crosslinked SWCNT/Hb was done with the help of crosslinking agent EDC (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide). The UV-Vis and FTIR spectroscopy of SWCNT/Hb networks showed that Hb maintained its natural structure and kept good stability. In addition with this, scanning electron microscopy (SEM) illustrated that SWCNT/Hb networks had a featured layered structure and Hb being strongly liked with SWCNT surface. Cyclic voltammetry (CV) was used to study and to optimize the performance of the resulting modified electrode. The cyclic voltammetric (CV) responses of SWCNT/Hb networks in pH 7.0 exhibit prominent redox couple for the FeIII/II redox process with a midpoint potential of -0.46 V and -0.34, cathodic and anodic respectively. Furthermo...
Herein, we propose a new approach to fabricate an enzyme electrode based on immobilization of glu... more Herein, we propose a new approach to fabricate an enzyme electrode based on immobilization of glucose oxidase (GOD) with multiporous nanofibers (MPNFs) of SnO 2 on Prussian blue (PB) modified gold (Au) electrode with chitosan. MPNFs of SnO 2 were synthesized by electrospinning method from the tin. Prussian blue was electrochemically deposited onto an Au electrode. GOD was then co-immobilized with the nanofibers on the surface of the PB modified gold electrode by using chitosan. The immobilized GOD/MPNFs onto the PB-Au presented faster, more stable and sensitive amperometric response to detecting glucose. Hydrogen peroxide (H 2 O 2) produced via Glucose oxidation and glucose reaction was detected by Prussian blue. The linear response dependence on glucose concentration was observed in a range of 0.5-5 mM and a detection limit of 0.05 mM at 3 signal/noise ratio. Because of unique structural characteristics at the nanoscale level, multiporous nanofibers (MPNFs) of SnO 2 is an ideal candidate for matrices in biosensing.
A new 3-dimensional (3D) network of crosslinked Horseradish Peroxidase/Carbon Nanotube (HRP/CNT) ... more A new 3-dimensional (3D) network of crosslinked Horseradish Peroxidase/Carbon Nanotube (HRP/CNT) on a thiol-modified Au surface has been described in order to build up the effective electrical wiring of the enzyme units with the electrode. The synthesized 3D HRP/CNT network has been characterized with cyclic voltammetry and amperometry which results the establishment of direct electron transfer between the redox active unit of HRP and the Au surface. Electrochemical measurements reveal that the high biological activity and stability is exhibited by the immobilized HRP and a quasi-reversible redox peak of the redox centre of HRP was observed at about −0.355 and −0.275 V vs. Ag/AgCl. The electron transfer rate constant, K S and electron transfer coefficient α were found as 0.57 s −1 and 0.42, respectively. Excellent electrocatalytic activity for the reduction of H 2 O 2 was exhibited by the developed biosensor. The proposed biosensor modified with HRP/CNT 3D network displays a broader linear range and a lower detection limit for H 2 O 2 determination. The linear range is from 1.0 × 10 −7 to 1.2 × 10 −4 M with a detection limit of 2.2.0 × 10 −8 M at 3 σ. The Michaelies-Menten constant Kapp M value is estimated to be 0.19 mM. Moreover, this biosensor exhibits very high sensitivity, good reproducibility and long-time stability.
The innovation of nanoparticles assumes a critical part of encouraging and giving open doors and ... more The innovation of nanoparticles assumes a critical part of encouraging and giving open doors and conceivable outcomes to the headway of new era devices utilized as a part of biosensing. The focused on the quick and legitimate detecting of specific biomolecules using functionalized gold nanoparticles (Au NPs), and carbon nanotubes (CNTs) has turned into a noteworthy research enthusiasm for the most recent decade. Sensors created with gold nanoparticles or carbon nanotubes or in some cases by utilizing both are relied upon to change the very establishments of detecting and distinguishing various analytes. In this review, we will examine the current utilization of functionalized AuNPs and CNTs with other synthetic mixes for the creation of biosensor prompting to the location of particular analytes with low discovery cutoff and quick reaction.
A multiporous nanofiber (MPNFs) of SnO2 and chitosan has been used for the immobilization of a re... more A multiporous nanofiber (MPNFs) of SnO2 and chitosan has been used for the immobilization of a redox protein, hemoglobin (Hb), onto the surface of glassy carbon electrode (GCE). The multiparous nanofiber of SnO2 that has very high surface area is synthesized by using electrospinning technique through controlling the tin precursor concentration. Since the constructed MPNFs of SnO2 exposes very high surface area, it increases the efficiency for biomolecule-loading. The morphology of fabricated electrodes is examined by SEM observation and the absorbance spectra of Hb/(MPNFs) of SnO2 are studied by UV-Vis analysis. Cyclic Voltammetry and amperometry are employed to study and optimize the performance of the resulting fabricated electrode. After fabrication of the electrode with the Hb and MPNFs of SnO2, a direct electron transfer between the protein's redox centre and the glassy carbon electrode was established. The modified electrode has showed a couple of redox peak located at −0.29 V and −0.18 V and found to be sensitive to H2O2_ The fabricated electrode also exhibited an excellent electrocatalytic activity towards the reduction of H2O2. The catalysis currents increased linearly to the H2O2 concentration in a wide range of 5_0×10−6-1_5×10−4 M. Overall experimental results show that MPNFs of SnO2 has a role towards the enhancement of the electroactivity of Hb at the electrode surface. Thus the MPNFs of SnO2 is a very promising candidate for future biosensor applications.
International journal of biological macromolecules, Jan 3, 2018
A novel third generation HO biosensor is fabricated using multiporous SnO nanofiber/carbon nanotu... more A novel third generation HO biosensor is fabricated using multiporous SnO nanofiber/carbon nanotubes (CNTs) composite as a matrix for the immobilization of redox protein onto glassy carbon electrode. The multiporous nanofiber (MPNFs) of SnO is synthesized by electrospinning technique from the tin precursor. This nanofiber shows high surface area and good electrical conductivity. The SnO nanofiber/CNT composite increases the efficiency of biomolecule loading due to its high surface area. The morphology of the nanofiber has been evaluated by scanning electron microscopy (SEM). Cyclic Voltammetry and amperometry technique are employed to study and optimize the performance of the fabricated electrode. A direct electron transfer between the protein's redox centre and the glassy carbon electrode is established after fabrication of the electrode. The fabricated electrode shows excellent electrocatalytic reduction to HO. The catalysis currents increases linearly to the HO concentration ...
We report on a novel 3-dimensional (3D) network of crosslinked Cytochrome C/Carbon Nanotube (CytC... more We report on a novel 3-dimensional (3D) network of crosslinked Cytochrome C/Carbon Nanotube (CytC/CNT) on a thiol-modified gold surface which can establish direct electrical communication between the redox center of Cytochrome C and the electrode. Cyclic voltammograms (CVs) results showed a pair of well defined redox peaks for Cytochrome C, located at about −0.03 and +0.06 V, cathodic and anodic respectively. Additionally, the formal potential E 0 of adsorbed Cyt c was found to be 15 mV, a value close to that of native Cyt c. Based on 3D Cytochrome c and carbon nanotube network, a sensitive superoxide radical biosensor has been proposed. The biosensor showed high sensitivity and lower detection limit of 0.3 M of superoxide.
The synthesis of a network of crosslinked carbon nanotube/hemoglobin (CNT/Hb) on a thiol-modified... more The synthesis of a network of crosslinked carbon nanotube/hemoglobin (CNT/Hb) on a thiol-modified Au surface and its use as sensor for H₂O₂ is reported. The constructed CNT/Hb 3-D network exhibits high conductivity by expediting the electrical transfer from Hb to the Au electrode and has a high electrocatalytic property for sensing hydrogen peroxide (H₂O₂). CNTs were first oxidized by treatment with concentrated nitric acid for 10h and functionalized by reaction with the thiol group of 4-aminothiophenol and Hb was also reacted with 4-aminothiophenol. These modified CNTs and modified Hb were immobilized on a 4-aminothiophenol monolayer-modified Au electrode by co-electropolymerization by repetitive cyclic voltammetry scans ranging between -0.1 and +1.1 V (versus Ag/AgCl). Cyclic voltammogram (CV) and amperometry were employed to study electrochemical properties of the modified electrodes. Direct electrical communication between the redox center of Hb and an Au electrode was established through 3-D network of crosslinked CNT/Hb. The Hb present in the 3-D CNT/Hb network exhibited a pair of quasi-reversible redox peaks with a midpoint potential of -0.225 V and -0.075, cathodic and anodic respectively. The electron transfer rate constant, K(S) and electron transfer co-efficient α were found to be 0.51 s⁻¹ and 0.58, respectively. The modified electrode was used as a biosensor and exhibited a high sensitivity, long linear range and lower detection limit to H₂O₂, under optimal conditions. The apparent Michaelis-Menten constant (K(m)) and Hb adsorption in the CNT/Hb network with average surface coverage of were found to be 0.19 mM and 4.8×10⁻¹⁰ mol cm⁻², respectively. This system should be very useful for other sensing applications.
A new method of forming proteinlipid film by spreading human serum albumin (HSA) solution direct... more A new method of forming proteinlipid film by spreading human serum albumin (HSA) solution directly on the subphase's interface covered with a layer of octadecylamine (ODA) was studied, with HSA as model protein. The optimum equilibrium time of HSA interacting with ...
The challenges of a heme protein and enzyme-based H2O2 sensor was subdued by developing a highly ... more The challenges of a heme protein and enzyme-based H2O2 sensor was subdued by developing a highly sensitive and practically functional amperometric gold nanoparticles (Au NPs)/SnO2 nanofibers (SnO2 NFs) composite sensor. The composite was prepared by mixing multiporous SnO2 NFs (diameter: 120–190 nm) with Au NPs (size: 3–5 nm). The synthesized Au NPs/SnO2 NFs composite was subsequently coated on a glassy carbon electrode (GCE) and displayed a well-defined reduction peak during a cyclic voltammetry (CV) analysis. The SnO2 NFs prevented the aggregation of Au NPs through its multiporous structure and enhanced the catalytic response by 1.6-fold. The SnO2 NFs-supported GCE/Au NPs/SnO2 NFs composite sensor demonstrated a very good catalytic activity during the reduction of hydrogen peroxide (H2O2) that displayed rapid amperometric behavior within 6.5 s. This sensor allowed for highly sensitive and selective detection. The sensitivity was 14.157 µA/mM, the linear detection range was from 49...
In this study, Titaium dioxide (TiO2) nanotubes (TNTs) were synthesized by a simple electrochemic... more In this study, Titaium dioxide (TiO2) nanotubes (TNTs) were synthesized by a simple electrochemical anodization method. TNTs were characterized by Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscope (TEM), UV-Vis Diffuse Reflectance Spectra and Photoluminescence (PL) Spectra to identify the morphology, crystalline phase and photocatalytic activity under the visible light. . The morphological analyses revealed that the inner diameter, and tube length of the synthesized TNTs has an average value of 60 nm, and 900 nm, respectively. The wall thickness of the TNTs is of 11 nm. Theobserved TNTs have nanotubular shape. The absorption edge in the visible range at around 400-460 nm obtained from UV-Vis Diffuse Reflectance Spectrum analysis. In addition, the PL spectral peak identified at around 400nm and 590 nm. The finding shows thatthe synthesized TNTs made by electrochemical anodization method has photocatalytic properties and can be used as a photocataly...
Biomedical Journal of Scientific & Technical Research, 2018
One of the most striking nanostructured materials is tin oxide (SnO 2) which has been used as nan... more One of the most striking nanostructured materials is tin oxide (SnO 2) which has been used as nanotubes, nanoparticles, nanowires, and nanorods [21,22]. Nanostructured SnO 2 possesses high surface area, nontoxicity, excellent biocompatibility, catalytic activity and chemical stability [23] which makes it suitable for various applications such as solar cells, electrochemistry, and biosensor [24-26]. We have fabricated a new one-dimensional nano-morphology of SnO 2 recently with the higher surface area and
A novel hydrogen peroxide biosensor has been designed based on the co-immobilization of hemoglobi... more A novel hydrogen peroxide biosensor has been designed based on the co-immobilization of hemoglobin (Hb), TiO 2 nanotubes and methylene blue (MB) onto a glassy carbon (GC) electrode. The titania nanotube arrays were directly grown on a Ti substrate using anodic oxidation first; and then detached from the Ti substrate using ultrasonication. A pair of well-defined redox peaks of Hb, enhanced by MB, appeared at an applied potential around À0.425 V, revealing that the immobilized Hb exhibits direct electrochemistry. Our electrochemical study shows that the immobilized Hb remains highly bioactive and displays excellent electrocatalytic response toward H 2 O 2. The effect of pH and applied electrode potential in H 2 O 2 sensing has been systemically studied. Besides the advantages of fast response and high stability, under the optimized conditions the linearity of the developed biosensor for the detection of H 2 O 2 was observed from 2 Â 10 À7 to 1.6 Â 10 À4 M with a detection limit as low as 8 Â 10 À8 M (based on S/N = 3).
A multiporous nanofiber (MPNFs) of SnO2 and chitosan has been used for the immobilization of a re... more A multiporous nanofiber (MPNFs) of SnO2 and chitosan has been used for the immobilization of a redox protein, hemoglobin (Hb), onto the surface of glassy carbon electrode (GCE). The multiporous nanofiber of SnO2 that has very high surface area is synthesized by using electrospinning technique through controlling the tin precursor concentration. Since the constructed MPNFs of SnO2 exposes very high surface area, it increases the efficiency for biomolecule-loading. The morphology of fabricated electrodes is examined by SEM observation and the absorbance spectra of Hb/(MPNFs) of SnO2 are studied by UV-Vis analysis. Cyclic Voltammetry and amperometry are employed to study and optimize the performance of the resulting fabricated electrode. After fabrication of the electrode with the Hb and MPNFs of SnO2, a direct electron transfer between the protein’s redox centre and the glassy carbon electrode was established. The modified electrode has showed a couple of redox peak located at -0.29 V...
The fabrication of a crosslinked network of glucose oxidase-horseradish peroxidase/tin oxide (GOx... more The fabrication of a crosslinked network of glucose oxidase-horseradish peroxidase/tin oxide (GOx-HRP/SnO2), immobilized on glassy carbon electrode (GCE) and its utilization as a sensor for glucose detection has been reported. The 3-D network established with GOx-HRP/SnO2 has possessed high sensitivity and stability by performing the electrocatalytic features in sensing of glucose. The turbidity of fabrication has been scanned and analyzed using UV-Vis Spectroscopy. The morphology and composition of the fabricated GOx-HRP modified multi-nanoporous SnO2 nanofibers were characterized by scanning electron microscopy (SEM). Cyclic voltammetry and amperometry were used to study the proposed electrochemical biosensor. The effect of applied electrode potential, pH and the concentration of glucose on the sensitivity of the biosensor have been systemically investigated which indicates that these systems should be very useful for other sensing applications
The fabrication of a network of glucose oxidase-horseradish peroxidase/tin oxide (GOx-HRP/SnO2), ... more The fabrication of a network of glucose oxidase-horseradish peroxidase/tin oxide (GOx-HRP/SnO2), immobilized onto a glassy carbon electrode (GCE) and its utilization as a biosensor for glucose detection is reported. The network established with GOx-HRP/SnO2 possess high sensitivity and stability by performing the electrocatalytic features in the sensing of glucose. The turbidity of fabrication had been scanned and analyzed using UV-vis spectroscopy. The morphology and composition of the fabricated GOx-HRP/SnO2 networks were characterized by scanning electron microscopy (SEM). Cyclic voltammetry and amperometry were employed to study the electrochemical properties of the proposed biosensor. The effect of applied electrode potential and pH were systemically investigated. The biosensor responds to glucose at work potential values between −400 mV, and exhibited a lower detection limit (0.025 mM) and long linear range (0.25 to 7.0 mM), and was resistant to common interferences.
In this work, we describe a new 3-dimensional (3D) network of crosslinked Horseradish Peroxidase/... more In this work, we describe a new 3-dimensional (3D) network of crosslinked Horseradish Peroxidase/Carbon Nanotube (HRP/CNT) on a thiol-modified Au surface in order to build up the effective electrical wiring of the enzyme units with the electrode. This is achieved by the electropolymerization of aniline-functionalized carbon nanotubes (CNTs) and 4-aminothiophenol -modified-HRP on a 4-aminothiophenol monolayer-modified Au electrode. The synthesized 3D HRP/CNT network has been characterized with cyclic voltammetry and amperometry, resulting the establishment direct electron transfer between the redox active unit of HRP and the Au surface. Electrochemical measurements reveal that the immobilized HRP exhibits high biological activity and stability and a quasi-reversible redox peak of the redox centre of HRP was observed at about −0.355 and −0.275 V vs. Ag/AgCl. The electron transfer rate constant, KS and electron transfer co-efficient are found to be 0.57 s-1 and 0.42, respectively. Base...
In this work, the direct electrochemistry of hemoglobin (Hb), which was immobilized on carbonyl f... more In this work, the direct electrochemistry of hemoglobin (Hb), which was immobilized on carbonyl functionalized single walled carbon nanotube (SWCNT) and deposited onto a gold (Au) electrode has been described. The synthesis of the network of crosslinked SWCNT/Hb was done with the help of crosslinking agent EDC (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide). The UV-Vis and FTIR spectroscopy of SWCNT/Hb networks showed that Hb maintained its natural structure and kept good stability. In addition with this, scanning electron microscopy (SEM) illustrated that SWCNT/Hb networks had a featured layered structure and Hb being strongly liked with SWCNT surface. Cyclic voltammetry (CV) was used to study and to optimize the performance of the resulting modified electrode. The cyclic voltammetric (CV) responses of SWCNT/Hb networks in pH 7.0 exhibit prominent redox couple for the FeIII/II redox process with a midpoint potential of -0.46 V and -0.34, cathodic and anodic respectively. Furthermo...
Herein, we propose a new approach to fabricate an enzyme electrode based on immobilization of glu... more Herein, we propose a new approach to fabricate an enzyme electrode based on immobilization of glucose oxidase (GOD) with multiporous nanofibers (MPNFs) of SnO 2 on Prussian blue (PB) modified gold (Au) electrode with chitosan. MPNFs of SnO 2 were synthesized by electrospinning method from the tin. Prussian blue was electrochemically deposited onto an Au electrode. GOD was then co-immobilized with the nanofibers on the surface of the PB modified gold electrode by using chitosan. The immobilized GOD/MPNFs onto the PB-Au presented faster, more stable and sensitive amperometric response to detecting glucose. Hydrogen peroxide (H 2 O 2) produced via Glucose oxidation and glucose reaction was detected by Prussian blue. The linear response dependence on glucose concentration was observed in a range of 0.5-5 mM and a detection limit of 0.05 mM at 3 signal/noise ratio. Because of unique structural characteristics at the nanoscale level, multiporous nanofibers (MPNFs) of SnO 2 is an ideal candidate for matrices in biosensing.
A new 3-dimensional (3D) network of crosslinked Horseradish Peroxidase/Carbon Nanotube (HRP/CNT) ... more A new 3-dimensional (3D) network of crosslinked Horseradish Peroxidase/Carbon Nanotube (HRP/CNT) on a thiol-modified Au surface has been described in order to build up the effective electrical wiring of the enzyme units with the electrode. The synthesized 3D HRP/CNT network has been characterized with cyclic voltammetry and amperometry which results the establishment of direct electron transfer between the redox active unit of HRP and the Au surface. Electrochemical measurements reveal that the high biological activity and stability is exhibited by the immobilized HRP and a quasi-reversible redox peak of the redox centre of HRP was observed at about −0.355 and −0.275 V vs. Ag/AgCl. The electron transfer rate constant, K S and electron transfer coefficient α were found as 0.57 s −1 and 0.42, respectively. Excellent electrocatalytic activity for the reduction of H 2 O 2 was exhibited by the developed biosensor. The proposed biosensor modified with HRP/CNT 3D network displays a broader linear range and a lower detection limit for H 2 O 2 determination. The linear range is from 1.0 × 10 −7 to 1.2 × 10 −4 M with a detection limit of 2.2.0 × 10 −8 M at 3 σ. The Michaelies-Menten constant Kapp M value is estimated to be 0.19 mM. Moreover, this biosensor exhibits very high sensitivity, good reproducibility and long-time stability.
The innovation of nanoparticles assumes a critical part of encouraging and giving open doors and ... more The innovation of nanoparticles assumes a critical part of encouraging and giving open doors and conceivable outcomes to the headway of new era devices utilized as a part of biosensing. The focused on the quick and legitimate detecting of specific biomolecules using functionalized gold nanoparticles (Au NPs), and carbon nanotubes (CNTs) has turned into a noteworthy research enthusiasm for the most recent decade. Sensors created with gold nanoparticles or carbon nanotubes or in some cases by utilizing both are relied upon to change the very establishments of detecting and distinguishing various analytes. In this review, we will examine the current utilization of functionalized AuNPs and CNTs with other synthetic mixes for the creation of biosensor prompting to the location of particular analytes with low discovery cutoff and quick reaction.
A multiporous nanofiber (MPNFs) of SnO2 and chitosan has been used for the immobilization of a re... more A multiporous nanofiber (MPNFs) of SnO2 and chitosan has been used for the immobilization of a redox protein, hemoglobin (Hb), onto the surface of glassy carbon electrode (GCE). The multiparous nanofiber of SnO2 that has very high surface area is synthesized by using electrospinning technique through controlling the tin precursor concentration. Since the constructed MPNFs of SnO2 exposes very high surface area, it increases the efficiency for biomolecule-loading. The morphology of fabricated electrodes is examined by SEM observation and the absorbance spectra of Hb/(MPNFs) of SnO2 are studied by UV-Vis analysis. Cyclic Voltammetry and amperometry are employed to study and optimize the performance of the resulting fabricated electrode. After fabrication of the electrode with the Hb and MPNFs of SnO2, a direct electron transfer between the protein's redox centre and the glassy carbon electrode was established. The modified electrode has showed a couple of redox peak located at −0.29 V and −0.18 V and found to be sensitive to H2O2_ The fabricated electrode also exhibited an excellent electrocatalytic activity towards the reduction of H2O2. The catalysis currents increased linearly to the H2O2 concentration in a wide range of 5_0×10−6-1_5×10−4 M. Overall experimental results show that MPNFs of SnO2 has a role towards the enhancement of the electroactivity of Hb at the electrode surface. Thus the MPNFs of SnO2 is a very promising candidate for future biosensor applications.
International journal of biological macromolecules, Jan 3, 2018
A novel third generation HO biosensor is fabricated using multiporous SnO nanofiber/carbon nanotu... more A novel third generation HO biosensor is fabricated using multiporous SnO nanofiber/carbon nanotubes (CNTs) composite as a matrix for the immobilization of redox protein onto glassy carbon electrode. The multiporous nanofiber (MPNFs) of SnO is synthesized by electrospinning technique from the tin precursor. This nanofiber shows high surface area and good electrical conductivity. The SnO nanofiber/CNT composite increases the efficiency of biomolecule loading due to its high surface area. The morphology of the nanofiber has been evaluated by scanning electron microscopy (SEM). Cyclic Voltammetry and amperometry technique are employed to study and optimize the performance of the fabricated electrode. A direct electron transfer between the protein's redox centre and the glassy carbon electrode is established after fabrication of the electrode. The fabricated electrode shows excellent electrocatalytic reduction to HO. The catalysis currents increases linearly to the HO concentration ...
We report on a novel 3-dimensional (3D) network of crosslinked Cytochrome C/Carbon Nanotube (CytC... more We report on a novel 3-dimensional (3D) network of crosslinked Cytochrome C/Carbon Nanotube (CytC/CNT) on a thiol-modified gold surface which can establish direct electrical communication between the redox center of Cytochrome C and the electrode. Cyclic voltammograms (CVs) results showed a pair of well defined redox peaks for Cytochrome C, located at about −0.03 and +0.06 V, cathodic and anodic respectively. Additionally, the formal potential E 0 of adsorbed Cyt c was found to be 15 mV, a value close to that of native Cyt c. Based on 3D Cytochrome c and carbon nanotube network, a sensitive superoxide radical biosensor has been proposed. The biosensor showed high sensitivity and lower detection limit of 0.3 M of superoxide.
The synthesis of a network of crosslinked carbon nanotube/hemoglobin (CNT/Hb) on a thiol-modified... more The synthesis of a network of crosslinked carbon nanotube/hemoglobin (CNT/Hb) on a thiol-modified Au surface and its use as sensor for H₂O₂ is reported. The constructed CNT/Hb 3-D network exhibits high conductivity by expediting the electrical transfer from Hb to the Au electrode and has a high electrocatalytic property for sensing hydrogen peroxide (H₂O₂). CNTs were first oxidized by treatment with concentrated nitric acid for 10h and functionalized by reaction with the thiol group of 4-aminothiophenol and Hb was also reacted with 4-aminothiophenol. These modified CNTs and modified Hb were immobilized on a 4-aminothiophenol monolayer-modified Au electrode by co-electropolymerization by repetitive cyclic voltammetry scans ranging between -0.1 and +1.1 V (versus Ag/AgCl). Cyclic voltammogram (CV) and amperometry were employed to study electrochemical properties of the modified electrodes. Direct electrical communication between the redox center of Hb and an Au electrode was established through 3-D network of crosslinked CNT/Hb. The Hb present in the 3-D CNT/Hb network exhibited a pair of quasi-reversible redox peaks with a midpoint potential of -0.225 V and -0.075, cathodic and anodic respectively. The electron transfer rate constant, K(S) and electron transfer co-efficient α were found to be 0.51 s⁻¹ and 0.58, respectively. The modified electrode was used as a biosensor and exhibited a high sensitivity, long linear range and lower detection limit to H₂O₂, under optimal conditions. The apparent Michaelis-Menten constant (K(m)) and Hb adsorption in the CNT/Hb network with average surface coverage of were found to be 0.19 mM and 4.8×10⁻¹⁰ mol cm⁻², respectively. This system should be very useful for other sensing applications.
A new method of forming proteinlipid film by spreading human serum albumin (HSA) solution direct... more A new method of forming proteinlipid film by spreading human serum albumin (HSA) solution directly on the subphase's interface covered with a layer of octadecylamine (ODA) was studied, with HSA as model protein. The optimum equilibrium time of HSA interacting with ...
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Papers by A.K.M. Kafi