Graphene Oxide Chitosan Research Articles

Preparation and characterization of graphene oxide/chitosan composite aerogel with high adsorption performance for Cr(VI) by a new crosslinking route

A new 3-glycidoxypropyltrimethoxysilane (KH-560) cross-linked graphene oxide/chitosan (GO/CS) composite aerogel was synthesized by sol-gel and freeze-drying methods. In this study, the three-dimensional porous network structure of composite aerogel was established by the self-assemble interaction between CS and GO, and by the crosslinking reaction between CS and KH-560. GO could enhance the strength of aerogels and keep porous structure stable, and KH-560 was used to avoid the dissolution of CS in acid conditions. The chemical properties, microstructure and thermal properties were investigated by FTIR, XPS, SEM, and TGA. The adsorption performance of composite aerogel was also studied. The results indicated that the process followed the Langmuir monolayer adsorption and pseudo-second-order kinetic model. The adsorption could reach equilibrium within 120 min, and the maximum adsorption capacity could reach up to 146 mg g −1 ; the aerogel adsorbent showed the good reusability and high adsorption capacity for Cr(VI) in coexistence with other ions.

Evaluation of a novel composite chitosan–graphene oxide membrane for NOM removal during water treatment

This paper describes the fabrication and evaluation of a novel composite chitosan-graphene oxide (CS-GO) membrane for the drinking water treatment. In this study, different molecular weight (MW) ranges, and quantities, of CS were used to crosslink GO nanosheets layer by layer (LBL) on a commercial ultrafiltration membrane, thereby fabricating a range of composite CS-GO membranes. CS molecules greatly enhanced the binding force between GO nanosheets by providing both hydrogen-bonding, electrostatic interactions, and C-OH and C-N chemical bonds. The stability of the CS-GO membranes was verified by their immersion in different solutions for up to 60 days. The interlayer spacing of the CS-GO composite membranes, which influences their permeability and separation performance, was found to be dependent on the MW range and dosage of CS. The interlayer spacing increased with the CS MW, but decreased with CS dose. The corresponding interlayer spacing of different CS-GO membranes ranged between 1.03 and 1.12 nm with 0.2 mg CS and 0.88–0.91 nm with 0.5 mg CS. When filtering solutions containing three representative NOM components and samples of a real surface water, the separation performance of CS-GO membranes was very high (>95% rejection) bovine serum albumin (BSA), sodium alginate (SA), and humic acid (HA) but was much lower (40–50% TOC rejection) for a real surface water collected from Beijing Olympic Park Lake (OP Lake). The results of this study have demonstrated that novel composite CS-GO membranes can be fabricated using a facile cross-linking method at room temperature, with tunable properties, and have considerable promise for water treatment applications.

Disposable Electrochemical Sensor Using Graphene Oxide–Chitosan Modified Carbon-Based Electrodes for the Detection of Tyrosine

Despite the many recent advances in disposable and wearable sensing technologies for point of care testing (POCT), few affordable, flexible, and disposable sensors are available for the detection of tyrosine (Tyr), a valuable biomarker for metabolic and neurodegenerative diseases. In this regard, the disposable screen-printed electrodes on flexible substrates are attractive. However, current screen-printed approaches for the detection of Tyr use rigid ceramic substrates, expensive metal nanoparticle conductive inks and stiff metal or metal oxide-based sensitive materials, that are not suitable for single-use disposable or wearable POCT devices. To address these challenges, this work presents a flexible and disposable electrochemical sensor using graphene oxide – chitosan (GO-CS) modified carbon-based electrodes for the detection of Tyr. The affordable and easy to fabricate sensor consists of a three-carbon electrode system screen printed on a flexible, low-cost polyvinyl chloride (PVC) substrate. GO and CS were chosen as the sensitive nanocomposite due to their natural abundance and excellent electrochemical sensing properties. Quantitative determination of Tyr using DPV revealed a linear proportional response between 1 and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$100~\mu \text{M}$ </tex-math></inline-formula> , with a correlation coefficient of 0.9993. The GO-CS-screen-printed carbon sensor (SPCS) also offers a linear range detection limit of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.86~\mu \text{M}$ </tex-math></inline-formula> , and excellent sensitivity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.0846\,\,\mu \text{A}\,\,\mu \text{M}^{-1}$ </tex-math></inline-formula> ) and repeatability (RSD =4.02%). The GO-CS-SPCS thereby provides a promising platform for the active sensing elements of single-use, disposable, and wearable POCT devices suitable for early diagnosis and monitoring of metabolic or neurodegenerative diseases or nutritional management.

Effect of sonication time and heat treatment on the structural and physical properties of chitosan/graphene oxide nanocomposite films

This study determined the effect of ultrasonication time (30, 60, and 120 min) and heat treatment (30, 60, and 120 °C) on the structure and properties of the chitosan/ graphene oxide (CSGO) composite films. Graphene oxide (GO) nanosheets with thickness of ∼1 nm was obtained after 120 min of sonication, as observed using atomic force microscopy (AFM). The incorporation of highly sonicated GO significantly (p < 0.05) improved both visible and ultraviolet (UV) light barrier properties of chitosan (CS) films. The heating temperature of 120 °C improved the hydrophobicity of the CSGO composite films, as demonstrated by contact angle analysis. Finally, all films were completely degradable within 28 days in a soil compost. The CSGO composites are potential green alternatives to petrochemical-based food packaging materials.

Phenylalanine-responsive fluorescent biosensor based on graphene oxide-chitosan nanocomposites catalytic film for non-destructive fish freshness grading

An optical enzymatic phenylalanine biosensor for non-invasive evaluation of fish freshness using biofluid from the fish body surface has been developed based on phenylalanine dehydrogenase (PDH) and nicotinamide adenine dinucleotide (NAD+) chemisorbed on the graphene oxide-chitosan (GO/CT) nanocomposites film. The immobilized PDH on the biosensor surface via EDC/NHS coupling strategy catalyzed the oxidative deamination of phenylalanine to phenylpyruvate, and concomitantly converted the cofactor NAD+ (oxidized form) to fluorophore NADH (reduced form), which can be quantified by using fluorescence spectrophotometer. The phenylalanine-responsive fluorescent biosensor showed a dynamic linear concentration range between 0.03 mM and 0.24 mM phenylalanine at 644 nm emission wavelength with an excitation wavelength of 320 nm. The limit of detection (LOD) of the fluorometric phenylalanine biosensor was estimated at 0.02 mM with a fast response time of 1 min. No significant interference by amines-synthesized amino acids, such as histamine, creatine, sarcosine, creatinine, tyrosine and uric acid at typical physiological levels commonly co-exist with phenylalanine in the biofluid metabolite of fish towards fresh fish quality grading. Validation study of the GO/CT catalytic film revealed excellent practicality of the biosensor in biological fluid sample of tuna fish (Euthynnus affinis) for detection of phenylalanine. The proposed GO/CT nanocomposites biofilm offers rapid test that can be assessed with an easy manner to rapidly analyze large number of samples in a short period of time.

X-ray Photoelectron Spectroscopy Analysis of Chitosan-Graphene Oxide-Based Composite Thin Films for Potential Optical Sensing Applications.

In this study, X-ray photoelectron spectroscopy (XPS) was used to study chitosan–graphene oxide (chitosan–GO) incorporated with 4-(2-pyridylazo)resorcinol (PAR) and cadmium sulfide quantum dot (CdS QD) composite thin films for the potential optical sensing of cobalt ions (Co2+). From the XPS results, it was confirmed that carbon, oxygen, and nitrogen elements existed on the PAR–chitosan–GO thin film, while for CdS QD–chitosan–GO, the existence of carbon, oxygen, cadmium, nitrogen, and sulfur were confirmed. Further deconvolution of each element using the Gaussian–Lorentzian curve fitting program revealed the sub-peak component of each element and hence the corresponding functional group was identified. Next, investigation using surface plasmon resonance (SPR) optical sensor proved that both chitosan–GO-based thin films were able to detect Co2+ as low as 0.01 ppm for both composite thin films, while the PAR had the higher binding affinity. The interaction of the Co2+ with the thin films was characterized again using XPS to confirm the functional group involved during the reaction. The XPS results proved that primary amino in the PAR–chitosan–GO thin film contributed more important role for the reaction with Co2+, as in agreement with the SPR results.

Layer-by-layer of graphene oxide-chitosan assembly on PVA membrane surface for the pervaporation separation of water-isopropanol mixtures

A graphene oxide/chitosan polyelectrolyte layer was used to modify the surface of a polyvinyl alcohol/tetraethyl orthosilicate membrane by layer-by-layer interfacial complexation and, thus, improve the pervaporation characteristics. The interfacial complexation between the chitosan and graphene oxide was confirmed by Fourier-transform infrared and X-ray photoelectron spectroscopy; the changes in surface hydrophilicity after layer-by-layer modification were examined by contact angle measurements, and the morphology of the layer-by-layer membrane was elucidated by field-emission scanning electron microscopy analysis. The pervaporation performance of the modified membranes was evaluated by performing the separation of water-isopropanol (IPA) azeotropes under different operating conditions. In the pervaporation experiments, the best performance was obtained using a membrane with 15 chitosan-GO layers (denoted 15L-L(CH-GO)). For this membrane, the flux increased from 13.6 to 76.4 g/m2h and the separation factor decreased from 56,720 to 4,001 as the feed temperature was varied from 30 to 60 °C for an 80: 20 (w/w) IPA/water feed. The apparent permeation activation energies were calculated and that of IPA (122.8 kJ/mol) was greater than that of water (47.4 kJ/mol).

Alkynyl-Based sp 2 Carbon-Conjugated Covalent Organic Frameworks with Enhanced Uranium Extraction from Seawater by Photoinduced Multiple Effects

Biofouling is a major obstacle to the efficient extraction of uranium from seawater due to the numerous marine microorganisms in the ocean. Herein, we report a novel amidoxime (AO) crystalline cova...

Iron oxides decorated graphene oxide/chitosan composite beads for enhanced Cr(VI) removal from aqueous solution

This study is the first to evaluate the effects of Iron oxides (FeOx) species and their decoration on graphene oxide/chitosan (GO/CS) composites for Cr(VI) removal and the possibility of Fe secondary pollution. Results show that Fe(III) is a better decoration material than Fe(II) and decoration through immersion-evaporation shows a higher adsorption capacity of Cr(VI) (Qe) than co-precipitation. Fe2O3-GO/CS as the only eco-friendly composite for enhanced Cr(VI) removal is further used for batch adsorption experiments, characterization, kinetics, isotherms, and thermodynamic studies. It is found that Cr(VI) removal mainly includes electrostatic attraction between Cr(VI) oxyanions and surface -NH3+ and -OH2+, and the adsorbed Cr(VI) partially reduces to Cr(III). Qe increases with the increasing initial Cr(VI) concentration, contact time, and temperature, while decreases with the increasing pH and mass and volume ratio (m/v). The coexisting ions (Cl−, NO3−, SO42−, PO43−, As, Fe, and Pb) can cause an obvious decrease of Qe. The removal efficiency (Re) and Qe are 94.3% and 83.8 mg/g, respectively under the optimal conditions. After five times of regeneration, Re is still as high as 84% and Qe drops about 2.6%. Cr(VI) adsorption is spontaneous and endothermic, which is best fitted with the Sips model, and the fitted maximum Qe is 131.33 mg/g.

Designing chitosan nanoparticles embedded into graphene oxide as a drug delivery system

We investigated a novel drug delivery system comprising nanoparticles based on chitosan/graphene oxide (GO)/folic acid for targeted delivery of chemotherapeutic drugs. In this research, GO is accompanied with chitosan as natural cationic polysaccharide to increase compatibility. First, GO was synthesized, then chitosan was grafted to it by chemical interaction, and then chitosan nanoparticle and GO hybrid nanocomposite were synthesized. The resulting nanocarrier is analyzed via different characterization methods. FTIR and XRD results were used to show the chemical and structural information before and after modification of GO nanocarrier. FESEM image of GO observed showed the nanoparticle was successfully attached on the surface of GO sheets. The thermal decomposition obtained showed that the thermal stability has been extended by the grafted Chitosan chains to GO; also, the highest loading capacity with folic acid was related to graphene oxide–chitosan nanoparticle nanocomposite. Then, folic acid was loaded on nanocarrier and its release was assessed. Results of this research show the combination of chitosan and GO by chemical interaction leading to creating holes, which increase loading to 99.97% and release to 94% for 72 h.

Development of magnetic solid phase extraction based on magnetic chitosan-graphene oxide nanoparticles and deep eutectic solvents for the determination of flavonoids by high performance liquid chromatography.

An environmentally friendly magnetic solid phase extraction method was developed based on magnetic chitosan-graphene oxide nanoparticles and deep eutectic solvents (DESs) for the pre-concentration and isolation of flavonoids (apigenin, morin, naringenin, and quercetin) of natural orange juice, commercial apple juice, onion juice, green tea, and natural apple juice samples. DESs via hydrophilic and π-π interactions could increase the extraction performance. The immobilization of chitosan-graphene oxide on the surface of Fe3O4 nanoparticles improved their chemical properties and mechanical stability. In addition, the prepared magnetic nanoparticles with the hydrophilic polymeric network and the high surface area of the graphene oxide increased the access of binding sites and extraction performance. The use of DESs as desorption of solvent and the individual properties of MANPs provided the ability for high extraction recovery and accelerates the time to reach equilibrium. The principal variables that influence microextraction efficiency, including the extraction time, type of DES, stirring rate, desorption time, type of eluent solvent, and pH of the sample solution, were screened via the Plackett-Burman design and then the variables were optimized by the Box-Behnken design. Under the optimum conditions obtained, the developed method showed a good working range (R2 ≥ 0.9962). The limit of detection (LOD) and the limit of quantification (LOQ) ranged from 0.03 μg L-1 (morin) to 0.14 μg L-1 (naringenin) and from 0.09 μg L-1 (morin) to 0.46 μg L-1 (naringenin) variables, respectively. The intraday precision was in the range of 4.1-4.8. In order to experiment with the precision and applicability of the MSPE-DES method, spiking recovery studies were performed in beverages and vegetable samples (natural orange juice, onion juice, commercial apple juice, natural apple juice, and green tea). The recovery results for real samples were calculated as 90-102%.

Graphene oxide-chitosan hydrogel for adsorptive removal of diclofenac from aqueous solution: preparation, characterization, kinetic and thermodynamic modelling.

This work aimed at developing a natural compound-based hydrogel adsorbent to remove diclofenac as a model pharmaceutical from water. First, graphene oxide–chitosan (GO–CTS) and amine graphene oxide–chitosan (AGO–CTS) hydrogel adsorbents were synthesized via a facile mechanical mixing method. The synthesized materials were characterized through Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning and transmission electron microscopy (SEM and TEM), Raman spectroscopy, and thermogravimetric analysis (TGA) techniques. In the second stage, adsorption experiments were conducted to determine the best GO to CTS ratio and find the optimized adsorption parameters, including the initial drug concentration, adsorbent dosage, pH, and temperature. The results showed that the optimal GO to CTS mass ratio is 2 : 5 and thus the same ratio was selected as the AGO to CTS mass ratio to understand the effect of amine-functionalization on removal efficiency. The optimal adsorption parameters were determined to be pH of 5, Ci of 100 ppm and dosage of 1.5 g L−1, where 90.42% and 97.06% removal was achieved for optimal GO–CTS and AGO–CTS hydrogel adsorbents, respectively. Langmuir and Freundlich isotherms models were employed to investigate the adsorption behavior of diclofenac onto the synthesized hydrogels. The results revealed that the adsorption tends to be of the monolayer type and homogeneous, as the results were in better accordance with the Langmuir model than the Freundlich model. The thermodynamics of adsorption demonstrated that the adsorption is exothermic, exhibiting higher removal efficiency at lower temperatures. Furthermore, Gibb's free energy change of adsorption (ΔG) suggested that the adsorption is spontaneous, being more spontaneous for AGO–CTS than GO–CTS hydrogels. Finally, the regeneration ability of the hydrogel adsorbents was studied in five consecutive cycles. The adsorbent maintained its efficiency at a relatively high level for three cycles but a considerable decrease was observed between the third and the fourth cycle, indicating that the hydrogels were recoverable for three cycles.

Electrochemical Sensing Platform Based on Graphene Oxide-Chitosan for Simultaneous Determination of Some Antihypertensive Agents

Electrochemical Sensing Platform Based on Graphene Oxide-Chitosan for Simultaneous Determination of Some Antihypertensive Agents

Optical and electrical properties of biocompatible and novel (CS–GO) polymer nanocomposites

The objective of this paper is to give information about the optical and electrical characteristics measured of the CS–GO PNCs (chitosan-graphene oxide polymer nanocomposites), which is novel, biodegradable and biocompatible in nature. These nanocomposites have been synthesized by simple solution mixing technique trailed by ultrasonication treatment. The variation of GO nano-filler has shown a direct impact on the optical and electrical properties of the nanocomposite. According to the observations, optical absorption edge has a slightly shift towards the longer wavelength; while the optical band gap of the nanocomposite is constantly reduced on increasing the wt% of GO. In optical properties, the dielectric constant, dissipation factor and electrical conductivity have been found to increase with increasing wt% of GO in the PNC. Further, a shift in the relaxation frequency, at which dipole get relaxed indicating the interaction between the graphene and chitosan, has also been observed for different GO wt%. The conductivity of nanocomposites were increased to almost 10 times on increasing 2 wt% of GO. Taking into account the outcomes accomplished, the use of CS–GO PNC is reasonable for forthcoming advancement of optical sensors, and might be demonstrated as an expected possibility for the electrical or optoelectronic devices working at high frequencies.

Synthesis and Characterization of Chitosan and Graphene Oxide to Form a Nano-Composite Hydrogel for the Removal of Heavy Metal Ions

Chitosan is a natural polymer that has proved its uses in many research areas because of its wide range of properties specially its adsorption properties can purify water by sticking metallic ions to its surface. In the present study local bio waste of shrimp shells was converted into chitin and then to chitosan. Chitosan was extracted by the combination of different processes. Shrimp shells were dried, soaked in 4% NaOH solution for 20 h, soaked it in 4% HCl solution for 10 h, again treated with NaOH but with 2% concentration for 24 h, soaked in 1% HCl for 12 h and washed with distilled water. Treatment with NaOH deprotienize the shrimp shell and HCl is supposed to demineralize the sample. Deprotienized and demineralized samples were then decolorized with 1% KMnO4 for 1 h. Sample was then treated by it 1% oxalic acid for 3 h. Decolorized sample, called chitin is brilliant white in color was soaked in 65% NaOH solution for around 70 h and the chitosan was extracted. Graphene oxide was also synthesized separately. The chitosan-graphene oxide hydrogel was prepared by socializing graphene oxide sheets and chitosan chains. The FTIR results showed the characteristic peaks of chitosan while UV-Vis spectroscopy of graphene oxide also confirmed the formation of graphene. The hydrogel obtained from CS-GO was also characterized through XRD and FTIR spectroscopy. Different samples of wastewater from industries, as well as self-prepared sample of copper sulphate, zinc chloride, and nickel sulphate were treated with the CS-GO hydrogel to reduce the contaminations in water. The hydrogel was simply poured in water and water was shaken, it was found that all the colored solutions were either became transparent or their transparency was increased due to the treatment with CS-GO hydrogel. It proves that the CS-GO successfully reduced the concentration of contaminants from waste water and a visible change of color was seen in the samples. The UV-VIS spectroscopies were also performed on all samples and a remarkable increase in transmittance was observed in all samples treated with CS-GO hydrogel.

Graphene oxide-composited chitosan scaffold contributes to functional recovery of injured spinal cord in rats.

The study illustrates that graphene oxide nanosheets can endow materials with continuous electrical conductivity for up to 4 weeks. Conductive nerve scaffolds can bridge a sciatic nerve injury and guide the growth of neurons; however, whether the scaffolds can be used for the repair of spinal cord nerve injuries remains to be explored. In this study, a conductive graphene oxide composited chitosan scaffold was fabricated by genipin crosslinking and lyophilization. The prepared chitosan-graphene oxide scaffold presented a porous structure with an inner diameter of 18-87 μm, and a conductivity that reached 2.83 mS/cm because of good distribution of the graphene oxide nanosheets, which could be degraded by peroxidase. The chitosan-graphene oxide scaffold was transplanted into a T9 total resected rat spinal cord. The results show that the chitosan-graphene oxide scaffold induces nerve cells to grow into the pores between chitosan molecular chains, inducing angiogenesis in regenerated tissue, and promote neuron migration and neural tissue regeneration in the pores of the scaffold, thereby promoting the repair of damaged nerve tissue. The behavioral and electrophysiological results suggest that the chitosan-graphene oxide scaffold could significantly restore the neurological function of rats. Moreover, the functional recovery of rats treated with chitosan-graphene oxide scaffold was better than that treated with chitosan scaffold. The results show that graphene oxide could have a positive role in the recovery of neurological function after spinal cord injury by promoting the degradation of the scaffold, adhesion, and migration of nerve cells to the scaffold. This study was approved by the Ethics Committee of Animal Research at the First Affiliated Hospital of Third Military Medical University (Army Medical University) (approval No. AMUWEC20191327) on August 30, 2019.

Reduced graphene oxide-chitosan flexible nanocomposites for efficient bacteria capture and photothermal ablation

AbstractOne of the major public health concerns today is bacterial infection-associated diseases. Traditional antibacterial therapies are becoming less efficient because frequent and inadequate use of antibiotics has caused mutations in bacteria that led to many antibiotic-resistant bacterial strains. It is, therefore, crucial to develop novel antibacterial materials and strategies that will successfully combat both gram-positive and gram-negative bacteria. In the present study, we will demonstrate a simple and efficient method for bacteria capture and elimination through photothermal ablation. The developed material consists of a flexible Kapton substrate, coated with reduced graphene oxide-chitosan (rGO-CS) thin films. Reduced graphene oxide has strong absorption in the near-infrared (NIR) region, while chitosan has the ability to bind bacteria through electrostatic interactions. The K/rGO-CS device proved to capture and efficiently eradicate both planktonic Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) bacteria after 10 min of NIR (980 nm) irradiation.

Magnetic nanoparticle-decorated graphene oxide-chitosan composite as an efficient nanocarrier for protein delivery

Protein therapy has received significant importance in healthcare industry to combat a wide variety of diseases such as cancer, metabolic disorders, and autoimmune disease. However, the efficiency of in vitro and in vivo protein delivery is hindered by their protein instability and less life span. Herein, we prepared magnetic nanoparticles decorated with graphene oxide chitosan composite (Fe-GO-CS) as a nanocarrier for protein. Bovine serum albumin (BSA) is employed as a protein with the prepared nanocarrier to study its stability and activity. The structural and morphological analysis were carried out using XRD, FTIR, FESEM, VSM and Raman spectroscopy. SDS page analysis showed no remarkable change after exposing Fe-GO-BSA and Fe-GO-CS-BSA solution in trypsin after a time duration of 30 min and 3 h. The Fe-GO-CS exhibits a good drug loading and releasing profile when compared with Fe-GO composite and this nanocarrier protects the protein from enzymatic cleavage. Hence Fe-GO-CS composite is a better nanocarrier that can be applied for clinical applications practically.

Negative electrical tunability of chitosan–graphene oxide nanocomposites

Herein, we report negative anomalous electrical tunability of the nanocomposite chitosan and graphene oxide (CS–GO) films based upon the dependence of dielectric constant and resistivity on DC bias. The origin of such anomalous tunability can be traceable to the reversible transformation of GO to reduced graphene oxide. In this transformation, H+ ions are released from water or GO side groups and those of $${\text{NH}}_{3}^{ + }$$ from CS; both ions participate in the reversible reduction process. Here, the capacitance exhibits negative tunability such that the dielectric constant increases and the resistivity decreases with increasing of DC bias. To probe this new phenomenon, we studied GO concentrations from 0 to 15 wt.% and water contents from 0 to 25 wt.%. Our results suggest that chitosan–GO nanocomposites can be readily prepared for the development of novel devices required in flexible organic electronics.

Horseradish Peroxidase-Immobilized Graphene Oxide-Chitosan Gold Nanocomposites as Highly Sensitive Electrochemical Biosensor for Detection of Hydrogen Peroxide

The generation of fast electrochemical response with high sensitivity is a significant parameter for enzymatic biosensors. However, establishing nanocomposite based modified electrode with fast electron shuttling between enzymes and the electrode surface for determination of hydrogen peroxide (H2O2) is highly challenging. Herein, the present work aims to develop second generation horseradish peroxidase (HRP) biosensors using Au nanochains dropcasted over electrochemically reduced graphene oxide-chitosan (ERGO-CHIT), a bio-nanocomposite film modified glassy carbon electrode (GCE) for reduction of H2O2 is demonstrated. The experimental conditions including effect of pH, loading of enzyme on the electrode surface and concentration of redox mediator as electrolyte were optimized. As a result, the HRP/Au/ERGO-CHIT/GCE electrode shows a larger enhancement in cathodic current signal with sharp peak response for reduction of H2O2, which can be attributed to the presence of Au nanochains on the modified electrode which improves the electron transfer between heme (Fe2+/Fe3+) center of enzymes on the electrode and the redox mediator in the electrolyte solution. The presence of HQ redox mediator in the electrolyte solution have provided stable peak response and offered more beneficiary in lowering the operating potential for the detection of H2O2 (−0.1 V), thereby reducing the influence from interference species. From the amperometric measurements, the HRP/Au/ERGO-CHIT/GCE modified electrode revealed high sensitivity (368.01 μA mM−1 cm−2) and possesses wide linear range (0.01 to 6.31 mM) which is mainly due to the high surface area and conductivity offered by Au nanochains which are located between ERGO and HRP. The resultant HRP/Au/ERGO-CHIT/GCE was found to possess good operational stability, high reproducibility, repeatability with low detection limits (4 μM), and thus it could be applicable for sensitive and rapid responsive detection of H2O2 in biological, clinical and environmental samples.