Shodhganga@INFLIBNET: Application of conducting polymer based nanostructured materials in biosensor and supercapacitor Skip navigation DSpace logo Home Browse Universities & Departments Browse by : Upload Date Researcher/Guide Title Keyword Sign on to: My Shodhganga Receive email updates Edit Profile Shodhganga : a reservoir of Indian theses @ INFLIBNET The Shodhganga@INFLIBNET Centre provides a platform for research students to deposit their Ph.D. theses and make it available to the entire scholarly community in open access. DSpace logo 1.Shodhganga@INFLIBNET 2.University of Calcutta 3.Department of Chemistry Please use this identifier to cite or link to this item: http://hdl.handle.net/10603/172580 Title: Application of conducting polymer based nanostructured materials in biosensor and supercapacitor Researcher: Chowdhury, Ankan Dutta Guide(s): De, Amitabha Keywords: …

In this work we have used functionalized polyaniline (PAn) nanowires for fabrication of a biosensing platform which was exploited for fabrication of three different biosensors. In one effort, we have immobilized single-stranded DNA oligonucletide (ssdA) on this platform and have monitored its combination with the complementary strand (ssdT) at a concentration as low as 10 -18 M. Moreover we have immobilized glucose oxidase on this platform that could be used for amperometric detection of glucose in aqueous solution over a wide concentration range of 1μM-20mM. We could successfully immobilize Lamin A (LA) antibody on the platform and its response towards the Lamin A protein could be nicely demonstrated down to a concentration as low as 10 μm. Therefore, the efficiency of the general biosensing platform is established.

Present work describes development of a Au-polyaniline nanocomposite based glucose biosensor. Biosensor was constructed by immobilizing glucose oxidase (GOx) using a crosslinker onto the working electrode (Pt) modified by the nanocomposite dispersion. TEM, UV-vis and FT-IR spectroscopy revealed the presence of Au nanoparticles on Polyaniline surface and covalent attachment of GOx to the electrode via AuMP. This system was used for amperometric detection of glucose in aqueous solution over a wide concentration range of 1 puM–20 mM. The biosensor is effective for selective electrochemical glucose sensing with a detection limit of 11 M glucose concentration with excellent sensitivity of 14.63 p. Amm’cm in the presence of common interferents like Uric Acid (UA) and Ascorbic Acid (AA). Same kind of system was used for DNA detection and was proved to be a better option for DNA biosensing.

Monday, February 17, 2020 315a other diseases like atherosclerosis, multiple sclerosis, and HIV. In this study, we have presented an electrochemical method to detect SMEnzyme concentration in a faster and more sensitive way compared to other currently available commercial assays due to the successful amplification process of liposomal matrix. For the amplification process, a methylene blue (MB)-encapsulated sphingomyelin (SM)-based liposome has been constructed which can release of the encapsulated MB in presence of the target enzyme and can be detected on a working electrode. A gold-polyaniline embedded (Au-PAni) graphene quantum dots (N, S-GQDs) coated nanocomposites, prepared via interfacial polymerization and then self-assembly approach has been used to capture the released MB on a glassy carbon electrode for electrochemical Differential Pulse Voltammetric (DPV) analysis. To get …

Provided is an electrode for electrochemical measurement for detecting or quantitatively determining a target substance, the electrode comprising: a complex supported on a surface of the electrode, wherein the complex is a complex comprising a probe for the target substance, a quantum dot which binds to the probe and is doped with nitrogen and sulfur, and a conductive polymer nanowire in which a metal nanoparticle is embedded.

Carbon Quantum Dots (CQDs) are already emerged as an excellent sensing element for its exceptional behavior in fluorescence, biocompatibility, and water dispersibility. However, its poor stability, selectivity and reproducibility in complex medium still be a big problem for its practical application. To overcome this, in the work, we have developed a new type of carbon quantum dot-PSS fluorescent nanocomposites which has been used for specific Fe3+ detection. The polystyrene sulfonate (PSS) polymer not only stabilize the QDs but also produces specific sites for Fe3+ to make a co-ordinate complex via Fe3+-SO3. The detection limit is calculated as low as 1 ppm which is adequate for measuring Fe3+ in blood or water samples. The mechanism of the quenching is very specific towards the Fe3+ ion due to the presence of PSS which makes the sensor selective among other metal ions and possible interferences …

The exponential growth of electrochemical biosensors in the health monitoring sector indicates the enormous possibility of application in the near future. However, the fabricated electrodes are unstable with a high coefficient of variation, even though achieving highly sensitive detection of the target virus. In this study, we have developed a simple method of sensor electrode fabrication that has been used for electrochemical impedimetric detection. The modified sensor has been prepared by streptavidin biotinylation to make a highly stable matrix that generates a sensitive and reliable response for the detection of Norovirus with a low detection limit of 60 ag/mL. The stable matrix of sensor electrode and its optimized condition for bioconjugation make a consistent result of detection with a low variance value of less than 10%, confirming the superiority of the sensor in term of application. In addition, the specificity of the sensor has been compared with other viruses and sensing media which is highly satisfactory due to specific binding of the antibody on the sensor surface. The biosensor’s sensitivity in clinically isolated Norovirus is compared with real-time quantitative reverse transcription-polymerase chain (RT-qPCR) and found to be satisfactory for its practical application. The sensor fabrication and detection mechanism are straightforward and rapid, giving it a significant advantage over other electrochemical methods for its possible upgradation for kit development.

Development of disposable, rapid and convenient biosensor with high sensitivity and reliability is the most desired method of viral disease prevention. To achieve this goal, in this work, a practical impedimetric biosensor has been implemented into a disposable electrode on a screen‐printed carbon electrode (SPCE) for the detection of two mosquito‐borne viruses. The biosensor fabrication has step‐wisely carried out on the disposable electrode surface at room temperature: starting from conductive film formation, physical binding of the gold nanoparticles (AuNPs)‐polyaniline (PAni) into the conductive film, and biofunctionalization. To get the maximum efficiency of the antibody, biotinylated antibody has been conjugated on the surface of AuNP‐PAni /PAni‐SPCE via the streptavidin‐biotin conjugation method which is a critical factor for the high sensitivity. Using the antibody‐antigen interaction, this disposable …

The successful development of a label free sensing approach using the localized surface plasmon resonance (LSPR), controlling the distance between fluorescent CdZnSeS/ZnSeS quantum dots (QDs) and gold nanoparticles (AuNPs) has been established for the detection of virus. Here, we present a new combination of AuNPs and CdZnSeS/ZnSeS QDs linked with a peptide chain of 18 amino acids after functionalization in its both ends. The synthesized peptide has been used as a linker between these duos and provided the anchoring sides for the antibody conjugation. In the optimized condition, the fluorescent properties of the QDs have been enhanced due to the surface plasmon effect of the adjacent AuNPs. On the basis of the significance on LSPR sensing, we have attempted to detect different concentration of influenza virus in this work. The detection sensitivity has been analyzed by the quenched spectra …

Infectious viruses have been recognized as a deadly threat for mankind since the first civilization established on earth. After advancement of several technologies and prevention methods, there have still been several examples of serious virus outbreaks every year around the world, especially from high populated countries like India, China and North Africa’s region (Calder et al. 2003, Carroll et al. 2015, Cotterelle et al. 2005, Hjertqvist et al. 2006, Rahman et al. 2012, Yadav et al. 2012). There are considerable fears that such kinds of outbreaks can rapidly spread worldwide to become epidemics with devastating effects on populations and their social and economic impact. To achieve the goal, UNESCO’s latest vision encourages us to counter the above challenges by providing a ‘new way forward’through the development of an inclusive green society (Didham and Paul 2015). This report covers the main priority area of health safety by the detection of virus methodologies and its recent progress for the transition to a green society. Several significant ways to the techniques for analyzing different virus samples are discussed here.
To prevent the viral outbreak, the rapid identification and quantification of contagious virus in all possible samples as well as in food and water is of great significance in prompt treatment and effective management for illness. Conventional virus detection methods which are the most reliable method of diagnosis yet, such as Polymerase Chain Reaction (PCR) and branched-chain DNA test are not wellsuited for point-of-care diagnosis as they are time-consuming, expensive and also require intensive sample preparation with …

Signal amplification have been centralized in developing the highly reliable biosensor for analyte detection with a narrow detection window. We proposed an aptasensor to provide a highly sensitive early-stage diagnostic platform of dengue virus NS1 protein (DENV-NS1) by dual-approach – colorimetric and electrochemical detection. This work utilized two different aptamers specific to DENV-NS1: One conjugated to gold nanoparticles (AuNPs), forming AuNPs-Apt1 and its complementary sequence aptamer, forming AuNPs-Apt2. The unbound Apt1 of AuNPs-Apt1 by DENV-NS1 were to hybridize to AuNPs-Apt2 and induced a 3D-nanoassembled formation, resulting in DENV-NS1 concentration-dependent plasmonic color change. Occurrence of the hybridization of Apt1 and Apt2, the 3D-assembled hybridized aptamers of AuNPs was incubated with methylene blue (MB) solution, which intercalated a high number of …

The treatment for mosquito-borne viral diseases such as dengue virus (DENV), zika virus (ZIKV), and chikungunya virus (CHIKV) has become difficult due to delayed diagnosis processes. In addition, sharing the same transmission media and similar symptoms at the early stage of infection of these diseases has become more critical for early diagnosis. To overcome this, a common platform that can identify the virus with high sensitivity and selectivity, even for the different serotypes, is in high demand. In this study, we have attempted an electrochemical impedimetric method to detect the ZIKV, DENV, and CHIKV using their corresponding antibody-conjugated sensor electrodes. The significance of this method is emphasized on the fabrication of a common matrix of gold–polyaniline and sulfur, nitrogen-doped graphene quantum dot nanocomposites (Au-PAni-N,S-GQDs), which have a strong impedimetric response based only on the conjugated antibody, resulting in minimum cross-reactivity for the detection of various mosquito-borne viruses, separately. As a result, four serotypes of DENV and ZIKV, and CHIKV have been detected successfully with an LOD of femtogram mL−1.

The exponential growth of electrochemical biosensors in the health monitoring sector indicates the enormous possibility of application in the near future. However, the fabricated electrodes are unstable with a high coefficient of variation, even though achieving highly sensitive detection of the target virus. In this study, we have developed a simple method of sensor electrode fabrication that has been used for electrochemical impedimetric detection. The modified sensor has been prepared by streptavidin biotinylation to make a highly stable matrix that generates a sensitive and reliable response for Norovirus detection with a low detection limit of 60 ag/mL. The stable matrix of the sensor electrode and its optimized condition for bioconjugation make a consistent detection result with a low variance value of less than 10 %, confirming the superiority of the sensor in terms of application. In addition, the specificity of the …

Detection of single base mismatch in DNA has been achieved by various techniques. However, the detection of position of that mismatch in the DNA duplex sequence has not been adequately addressed. In the present work, sensing of positional change of DNA base mismatch is achieved, with enhanced detection limit, using methylene blue as a redox indicator in electrochemical differential pulse voltammetric method (DPV). Interfacially synthesized Gold Polyaniline nanocomposites (Au-PAni) is coated on Pt electrode and attached with thiol modified single stranded DNA to construct the sensor electrode. Position sensitive detection of a single base mismatch in oligomeric duplexes is achieved here, with a detection limit for concentration as low as 10−8 M for mixed oligomeric sequences and 10−6 M for dA-dT duplexes. In this case, the sensitivity of the electrode is 0.12 μA pM−1 cm−2. Reusable sensor electrode …

Sphingomyelinase (SMEnzyme) converts sphingomyelin into ceramide, modulating membrane properties and signal transduction which inactivates mutations and causes Niemann–Pick disease. Real‐time monitoring of SMEnzyme is also crucial as an important biomarker for several other diseases like atherosclerosis, multiple sclerosis, and HIV. In this study, we present an electrochemical method to detect SMEnzyme concentration that is more sensitive and much faster than currently available commercial assays. For detection and the amplification of the SMEnzyme signal, methylene blue (MB)-encapsulated sphingomyelin (SM)-based liposome with 50% cholesterol was synthesized via sonication method. Then the target SMEnzyme causes the free release of the MB from the MB-liposome formulation which can be detected on GCE||Au-PAni/N,S-GQDs electrode, prepared via interfacial polymerization and then …

Viral diseases are one of the most life-threatening diseases as they can erupt unpredictably and spread rapidly in any medium with a very small number of particles. Therefore, the key for lethal virus detection should be highly sensitive in the early-stage detection, which can help increase the chance of survival. Amplification of the detecting signal is one of the most promising mechanisms for the detection of low-concentration analytes. A proper amplification can develop such a kind of system where a small number of particles can produce intense signals for a prominent detection. Keeping this in mind, in this report, we have presented a fluorometric method to detect norovirus (NoV) by a newly developed fluorophore-labeled liposome and a magnetically modified Fe3O4 combined system. Homogeneously distributed amine-functionalized liposomes have been constructed filled with a strong fluorophore of calcein …

With the enormous increment of globalization and global warming, it is expected that the number of newly evolved infectious diseases will continue to increase. To prevent damage due to these infections, the development of a diagnostic method for detecting a virus with high sensitivity in a short time is highly desired. In this study, we have developed a disposable electrode with high-sensitivity and accuracy to evaluate its performances for several target viruses.
Results
Conductive silicon rubber (CSR) was used to fabricate a disposable sensing matrix composed of nitrogen and sulfur-co-doped graphene quantum dots (N,S-GQDs) and a gold-polyaniline nanocomposite (AuNP-PAni). A specific anti-white spot syndrome virus (WSSV) antibody was conjugated to the surface of this nanocomposite, which was successfully applied for the detection …

The critical goal of sensitive virus detection should apply in the early stage of infection, which may increase the probable survival rate. To achieve the low detection limit for the early stage where a small number of viruses are present in the sample, proper amplified signals from a sensor can make readable and reliable detection. In this work, a new model of fluorescent and electrochemical dual-mode detection system has been developed to detect virus, taking recombinant Chikungunya virus E1 protein (CHIK-VP) as an example. The hydrophobic quantum dots (QDs) embedded in the lipid bilayer of liposome and methylene blue (MB) encapsulated in the inner core of liposomes played a role of dual-signaling modulator. After CHIK-VP addition, the nanocomposites and APTES-coated Fe3O4 nanoparticles (Fe3O4 NPs) were conjugated with antibodies to form a sandwich structure and separated from the medium …

The social impact of virus spread is immeasurable. Vaccine prophylaxes take considerable time to develop because clinical trials are required. The best initial response to an emerging virus is establishing a virus detection technology adapted by simply preparing virus-specific antibodies. A virus detection system that detects two signals from one analyte has been developed to detect the target virus more sensitively and reliably. Plasmon regions on the surface of nanoparticles are effective in enhancing optical and electrochemical signals. Thus, CdSeTeS quantum dots (QDs) have been used as optical and electrochemical signal-generating materials. In contrast, gold nanoparticle–magnetic nanoparticle–carbon nanotube (AuNP–MNP–CNT) nanocomposites are used for the magnetic separation of the virus from interferences and for signal enhancement. In the presence of the target virus, the QDs optically show a …

Rapid increasing outbreak of Hepatitis E virus (HEV) shows an urgent need of HEV detection. Instead of time consuming and expensive RT-qPCR, an efficient and quick monitoring system is in utmost demand which can be comparable with the RT-qPCR in term of reliability and detection limit. An advanced platform for immunoassay has been constructed in this study by a nanozyme that constitutes anti-HEV IgG antibody-conjugated gold nanoparticles (Ab-AuNPs) as core and in situ silver deposition on the surface of Ab-AuNPs as outer shell. The virus has been entrapped on the nanocomposites while the silver-shell has decomposed back to the silver ions (Ag+) by adding a tetramethylbenzidine (TMBZ) and hydrogen peroxide (H2O2) which indirectly quantifies the target virus concentration. Counterpart to only applying nanozyme, by incorporation of the enhanced effect of Ag shell on the AuNP-based nanozyme …

Molybdenum disulfide (MoS2) and its associated nanocomposites are widely explored in different applications like capacitance, batteries, sensing etc. However, the nanosheet formation of MoS2 exhibits excellent properties for DNA adsorption without any further surface or probe DNA modification which makes it a suitable matrix for the less explored DNA sensing application. In this present work, an ultrasensitive electrochemical DNA biosensor, based on few layered MoS2 nanosheets blended with conducting polymer, polyaniline is constructed as a sensing platform and used as a DNA sensing probe via differential pulse voltammetric technique. The sensor works well even at concentrations as low as 10−15 M of target DNA without labeling or any use of amplifiers. The sensing performances show highly satisfactory results in case of serum samples and in presence of other interferrants. In addition, the sensor can …

A sensitive virus detection method applicable for an early stage increases the probability of survival. Here, we develop a simple and rapid detection strategy for the detection of the hepatitis E virus (HEV) by an electrocatalytic water oxidation reaction (WOR) using a platinum (Pt)-incorporated cobalt (Co)-based zeolite imidazole framework (ZIF-67). The surface cavity of ZIF-67 enables the rich loading of Pt NPs, and subsequent calcination etches the cavity, promoting the electrocatalytic activity of Pt-Co3O4 HCs. The Pt-Co3O4 HCs show excellent behavior for the WOR due to the synergistic interaction of Pt and Co3O4, evaluated by voltammetry and chronoamperometry. The synthesized Pt-Co3O4 HCs are conjugated with anti-HEV antibody (Ab@Pt-Co3O4 HCs); the electrocatalytic activity of Ab@Pt-Co3O4 HCs is combined with that of antibody-conjugated magnetic nanoparticles (MNPs) for HEV detection by a …

The dengue hemorrhagic fever or dengue shock syndrome has become a severe human fatal disease caused by infection with one of the four closely related but serologically distinct dengue viruses (DENVs). All four dengue serotypes are currently co-circulating throughout the subtropics and tropics. Since the fatality rate increases severely when a secondary infection occurs by a virus serotype different from that of the initial infection, serotype identification is equally important as virus detection. In this study, the development and validation of a rapid and quantitative DENV serotype-specific (serotypes 1–4) biosensor are reported by optimizing the stable system between cadmium selenide tellurium sulphide fluorescent quantum dots (CdSeTeS QDs) and gold nanoparticles (AuNPs). Four different nanoprobes are designed using each primer–probe serotype-specific hairpin single-stranded DNA covalently bound at …

Titanium(IV)-doped synthetic nanostructured iron(III) oxide (NITO) and polypyrrole (PPy) nanocomposites was fabricated by in situ polymerization using FeCl3 as initiator. The polymer nanocomposites (PNCs) and pure NITO were characterized by X-ray diffraction, Föurier transform infrared spectroscopy, scanning electron microscopy, electron dispersive X-ray spectroscopy, transmission electron microscopy, etc. Thermo gravimetric and differential thermal analyses showed the enhancement of thermal stability of PNCs than the pure polymer. Electrical conductivity of the PNCs had increased significantly from 0.793×10−2S/cm to 0.450S/cm with respect to the PPy, and that had been explained by 3-dimensional variable range hopping (VRH) conduction mechanisms. In addition, the specific capacitance of PNCs had increased from 147F/g to 176F/g with increasing NITO content than that of pure NITO (26F/g …

In this report, we have examined the distance- and size-dependent localized surface plasmon resonance (LSPR) between fluorescent quantum dots (QDs) and adjacent gold nanoparticles (AuNPs) to provide a comprehensive evaluation, aiming for practical application in biosensing platform. A series of peptides with different chain lengths, connected between QDs and AuNPs is initially applied to prepare various CdSe QDs-peptide-AuNP systems to optimize LSPR signal. Separation distance between two nanoparticles of these systems before and after conjugation is also confirmed by quantum mechanical modeling and corroborated with their LSPR influenced fluorescence variations. After detailed optimizations, it can be noted that larger sized AuNPs make strong quenching of QDs, which gradually shows enhancement of fluorescence with the increment of distance and the smaller sized AuNPs. Depending on …

Combination of magnetic nanomaterials with multifunctionality is an emerging class of materials that exhibit tremendous potential in advanced applications. Synthesizing such novel nanocomposites without compromising magnetic behavior and introducing added functional properties is proven challenging. In this study, an optically active quantum dot (QD) (core) encapsulated inside iron oxide (hollow shell) is prepared as the first electrochemical/fluorescence dual-modality probe. Presence of magnetic layer on the surface enables excellent magnetic property and the encapsulating of QDs on the hollow shell structure maintains the fluorescence with minimal quenching effect, endowing for potential application with fluorescence modality readout. We successfully demonstrate dual-modality sensing utilizing of QD-encapsulated magnetic hollow sphere nanoparticles (QD@MHS NPs) with magnetic separation ability …

The successful development of selective detection of cancer cells from normal cells is a highly demanded but challenging task. Herein, we have developed a rapid and label-free impedimetric biosensor for quantitative determination of cancer cells with high glycoprotein expression. Homogenously distributed 2–9 nm graphene quantum dots (GQDs) was anchored on the surface Fe3O4 through covalent bonding. Concovalin A (ConA) was then adhered onto GQDs by physical mixing to fabricate ConA-GQD@Fe3O4 nanosensing probe. A good dynamic range in the cell concentration of 5 × 102–1 × 105 cells mL-1 with LOD values of 246 and 367 cells mL-1 for HeLa and MCF-7, respectively, is obtained. The impedimetric responses to the cancerous HeLa and MCF-7 cells are 16.7 and 13.1 times higher than those of their original sensor electrodes. However, the interaction between sensing probe and normal …

Conducting polymers and related nanomaterials are widely used for different biosensing applications. In the present work gold nanoparticles (AuNP) incorporated polyaniline nanowires (PAn-NW) were used for fabrication of a novel biosensing platform. PAn-NW with AuNP (8–10nm) was treated with β-mercaptoethylamine (MEA) that leads to the formation of the NH2 functionalized PAn-AuNP in dispersed form. Immobilizing the functionalized dispersion on the Pt electrode makes a biosensing platform suitable for attachment of different biomolecules via NH2 functionality and sensing of the target elements in turn. Efficiency of the system as oligonucleotide (dA–dT) sensor was examined by immobilizing a single stranded oligonucleotide (ssdA) and monitoring its hybridization with target nucleotide (ssdT) following cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance …

It is well established that sodium borohydride, (NaBH4) is one of the most safe and attractive hydrogen-storage materials for H2 production. In this work, we have reported a zero valent Ruthenium–Cobalt (Ru–Co) based nanocluster incorporated conducting PEDOT/PSS nanocomposite as the catalyst for rapid hydrogen production from NaBH4. Initially, Ru–Co nanocluster was synthesized by reduction of a mixture of Ruthenium(III) chloride and Cobalt(II) chloride using sodium borohydride solution. Although the Ru–Co itself showed good synergistic catalytic effect as compared to bare Ru and Co nanoparticles, but their performance was found to be exceptionally good when incorporated into the conducting polymer (PEDOT/PSS). The obtained catalyst was characterized by TEM, EDX, XRD, four-probe conductivity measurements, etc. The hydrolysis kinetics showed that the 85 wt% NaBH4 + 15 wt% Ru–Co PEDOT …

Sensitive and accurate detection methods for infectious viruses are the pressing need for effective disease diagnosis and treatment. Herein, based on V2O5 nanoparticles-encapsulated liposomes (VONP-LPs) we demonstrate a dual-modality sensing platform for ultrasensitive detection of the virus. The sensing performance relies on intrinsic peroxidase and electrochemical redox property of V2O5 nanoparticles (V2O5 NPs). The target-specific antibody-conjugated VONP-LPs and magnetic nanoparticles (MNPs) enrich the virus by magnetic separation and the separated VONP-LPs bound viruses are hydrolyzed to release the encapsulated V2O5 NPs. These released nanoparticles from captured liposomes act as peroxidase mimics and electrochemical redox indicator resulting in noticeable colorimetric and robust electrochemical dual-signal. Utilizing the superiority of dual-modality sensor with two quantitative …

The interest in DNA–protein-based diagnostics has recently been growing enormously, which makes the separation process of DNA or protein from a cell extract extremely important. Unlike the traditional separation process, a novel approach is in demand which can nondestructively isolate the target biomolecules without sacrificing the other components in the mixture. In this study, we have demonstrated a new and simple separation technique by using well-established bifunctional Au–Fe3O4 nanocomposites as the separation nanoprobes to efficiently isolate the specifically targeted nanomolar concentrated DNA over 70% from its associate DNA–protein mixture in the presence of a magnetic field. The sensing accuracy of both as-separated DNA and protein are quantitatively examined by UV–vis spectroscopy, and then qualitatively validated by gel analysis. Results obtained in this study clearly demonstrated that …

The present study is on development of easy, facile and rapid synthetic methodologies for producing highly active low-cost bifunctional electrocatalysts for oxygen reduction/evolution reactions (ORR/OER) which are the key barriers in various electrochemical devices such as metal–air batteries, fuel cells and water splitting reaction. The synthesized PEDOT-CoMn2O4 nanocomposites from α-MnO2 nanorod favour 4e oxygen reduction process of oxygen to water and exhibit high ORR activities in the stable conducting platform of the polymer. The catalytic effect is studied by Linear Sweep Voltammetry using Rotating Disk Electrode at varying rotation speed (0 to 3000 rpm). Although the α-MnO2 nanorod does not show any OER/ORR activity, the spinel makes the difference and the nanocomposites of PEDOT – CoMn2O4 exhibit unexpected, surprisingly high ORR activities in their conducting and stable form. The …

Dengue surveillance trusts only on reverse transcription-polymerase chain reaction (RT-PCR) type methodologies for confirmation of dengue virus serotypes; however, its real time application is restricted due to the expensive, complicated, and time-consuming process. In search of a new sensing system, here, we have reported a two-way-detection method for Dengue virus (DENV) serotype identification along with DNA quantification by using a new class of nanocomposite of gold nanoparticles (AuNP) and nitrogen, sulfur codoped graphene quantum dots (N,S-GQDs). The N,S-GQDs@AuNP has been used for serotype detection via a simple fluorescence technique using four dye-combined probe DNAs which is further validated by confocal microscopy. The quantification of the DNA has been measured by the differential pulse voltammetric (DPV) technique using methyelene blue as a redox indicator. Results …

In this study, a tunable biosensor using the localized surface plasmon resonance (LSPR), controlling the distance between fluorescent CdZnSeS/ZnSeS quantum dots (QDs) and gold nanoparticles (AuNPs) has been developed for the detection of virus. The distance between the AuNPs and QDs has been controlled by a linkage with a peptide chain of 18 amino acids. In the optimized condition, the fluorescent properties of the QDs have been enhanced due to the surface plasmon effect of the adjacent AuNPs. Successive virus binding on the peptide chain induces steric hindrance on the LSPR behavior and the fluorescence of QDs has been quenched. After analyzing all the possible aspect of the CdZnSeS/ZnSeS QD-peptide-AuNP nanocomposites, we have detected different concentration of influenza virus in a linear range of 10−14 to 10−9 g mL−1 with detection limit of 17.02 fg mL−1. On the basis of the obtained …

A new method of label free sensing approach with superior selectivity and sensitivity towards virlabel-freeon is presented here, employing the localized surface plasmon resonance (LSPR) behavior of gold nanoparticles (AuNPs) and fluorescent CdSeTeS quantum dots (QDs). Inorganic quaternary alloyed CdSeTeS QDs were capped with L-cysteine via a ligand exchange reaction. Alternatively, citrate stabilized AuNPs were functionalized with 11-mercaptoundecanoic acid to generate carboxylic group on the gold surface. The carboxylic group on the AuNPs was subjected to bind covalently with the amine group of L-cysteine capped CdSeTeS QDs to form CdSeTeS QDs/AuNPs nanocomposites. The fluorescence of CdSeTeS QDs/AuNPs nanocomposite shows quenched spectrum of CdSeTeS QDs at 640 nm due to the close interaction with AuNPs. However, after successive addition of norovirus-like particles …

Multifunctional nanocomposites containing intrinsic property for serving as the sensing elements as well as targeted nanoconjugates are highly preferred in various therapeutic applications. In this work, nanocomposites of graphene quantum dots (GQDs) and Fe3O4 with conjugation of lectin protein, concanavalin A, to form GQD-ConA@Fe3O4 nanocomposites are developed for both detection of cancer cell and release of drugs to HeLa cells. The GQD-ConA@Fe3O4 nanocomposites deposited on Pt electrode can detect cancerous HeLa cells over normal endothelial cells with a dynamic linear range of 5 × 102 to 1 × 105 cells mL−1 with a detection limit of 273 cell mL−1. The GQD-ConA@Fe3O4 also can serve as nanocarriers for loading and delivering doxorubicin (Dox). The in vitro cell images show that the Dox concentration in HeLa cells is enhanced more than double in the presence of external magnetic …

In this paper, fabrication of a biosensing platform by covalent attachment of biomolecules on PAni nanowire (NW) decorated with gold nanoparticles (AuNP) has been reported. Efficiency of the platform has been evaluated after attachment of three different biomolecules viz. glucose oxidase (GOx), a single stranded DNA (ssDNA) and Lamin A antibody (LAA) for sensing of glucose, complementary DNA strand and Lamin A protein, respectively. Method of immobilization as well as method of detection was somewhat different for different systems. GOx and LAA were attached via NH2 functionalizations on AuNP while thiol-ended ssDNA was directly attached to AuNP surface. Sensing of glucose was monitored via chronoamperometry and the flow cell techniques while DNA detection was carried out via Differential Pulse Voltametry (DPV) and protein detection employing Electrochemical Impedance Spectroscopic (EIS …

Graphene quantum dots (GQDs) are a newly developed graphene family with good electrical conductivity and high theoretical capacitance, while halloysite nanotubes (HNTs) are naturally occurring layered mineral materials containing high active sites for energy storage support. The combination of HNTs and GQDs can offer a new strategy on the fabrication of eco-friendly electrode materials for high performance supercapacitor applications. Herein, an environmentally friendly GQD-HNT nanocomposite is fabricated in the presence of (3-aminopropyl)-triethoxysilane to provide increased charge storage sites as well as to allow for the fast charge transport for supercapacitor application. Morphological and surface analytical results show that 5–10 nm GQDs are homogeneously distributed on the surface of APTES-coated HNTs via amide linkage. This new and novel layered nanocomposite can provide accessible …

The development of robust and low cost electrode materials with superior electrochemical properties has been a subject of focus on energy storage devices. Herein, the development of N-doped graphene quantum dots (N-GQDs) deposited on Fe3O4-halloysite nanotubes (Fe3O4-HNTs) as active anode materials has been established for supercapacitor applications. The Fe3O4 nanoparticles synthesised by coprecipitation have been in-situ deposited on HNT surfaces following by the coating of (3-aminopropyl)-triexthoxysilane to anchor 4–10 nm N-GQDs via the formation of amide linkage. The N-GQD@Fe3O4-HNTs exhibits a high specific capacitance of 418 F g−1 and maintains good rate capability in neutral electrolyte solutions. In addition, the anode materials show excellent electrochemical performance with energy and power densities of 10.4–29 W h kg−1 and 0.25–5.2 kW kg−1, respectively. Such excellent …

The development of a fast-response sensing technique for detection of cysteine can provide an analytical platform for prescreening of disease. Herein, we have developed a fluorescence turn off–on fluorescence sensing platform by combining nitrogen-doped graphene quantum dots (N-GQDs) with V2O5 nanosheets for the sensitive and selective detection of cysteine in human serum samples. V2O5 nanosheets with 2–4 layers are successfully synthesized via a simple and scalable liquid exfoliation method and then deposited with 2–8 nm of N-GQDs as the fluorescence turn off–on nanoprobe for effective detection of cysteine in human serum samples. The V2O5 nanosheets serve as both fluorescence quencher and cysteine recognizer in the sensing platform. The fluorescence intensity of N-GQDs with quantum yield of 0.34 can be quenched after attachment onto V2O5 nanosheets. The addition of cysteine triggers …

Poly 3,4-ethylenedioxythiophene (PEDOT)- and polyaniline (PANI) nanocomposites were synthesized based on manganese dioxide in the form of Nanorod. Suitability of these composites was studied extensively as an electrode material for symmetric supercapacitor in a widened operating voltage window of 1.2 V. Role of manganese dioxide during reverse microemulsion polymerization in n-hexane medium for PEDOT and aqueous dispersion polymerization for PANI, have been accounted through X-ray photoelectron spectroscopy (XPS). Structural morphology as well as thermal characterization was carried out using XRD, SEM, TEM, IR and TGA. Charge storage mechanism in these nanocomposites have been investigated through cyclic voltammetry (CV) at different scan rates (2–20 mV/s), where intercalation of metal ion during reduction and de-intercalation upon oxidation predominate over surface adsorption …

A new and simple method for label free, rapid and inexpensive impedimetric sensing of Escherichia coli O157:H7 (a highly infectious and potentially fatal food and water borne pathogen) using antibody–antigen binding method based on covalently linked antibody on a conducting Polyaniline (PANI) film surface is reported. Electrochemical impedance spectroscopy (EIS) was used to test the sensitivity and effectiveness of the sensor electrode by measuring the change in impedance values of electrodes before and after incubation with different concentrations of bacteria. An equivalent electrical circuit model has also been proposed to explain the sensing mechanism. As small concentration as 102CFUmL−1 of E. coli O157:H7 were successfully detected on the Au/PANI/Glu/antibody sensor with the upper detection limit of 107CFUmL−1. The specificity of the sensor has been tested by comparing with two other strains …

The development of robust and low-cost sensing materials with superior selectivity and sensitivity for rapid detection of analytes in a wide variety of samples has attracted much attention. Herein, the N, S-codoped graphene quantum dots (N, S-GQDs) with high quantum yield were fabricated by one-pot hydrothermal method for highly sensitive and selective detection of nanomolar level of mercury ions (Hg2+) in water and wastewater. The as-prepared N, S-GQDs are uniform in size with mean particle size of 3.5 ± 0.5 nm. The doping of nitrogen atoms increases the quantum yield to 41.9%, while the introduction of sulfur atoms enhances the selectivity of Hg2+ via strong coordination interaction. The fluorescence intensity of N, S-GQDs is quenched proportionally after adding Hg2+ and a dynamic range of 4 orders of magnitude with limit of detection of 0.14 nM is obtained in deionized water. The N, S-GQDs …

A non-enzymatic approach towards cholesterol detection is presented here, exploiting the electrochemical non-enzymatic route of sensing which has a distinct advantage over other conventional enzymatic processes. Chemically converted Graphene modified with β-CD, being hydrophilic, electroactive and high surface area material, provides a platform for the electrochemical detection of cholesterol using Methylene Blue as redox indicator. Methylene Blue (MB) forms an inclusion complex with Grp-β-CD and emerges as a cholesterol sensing matrix. MB molecule is replaced by cholesterol molecule and moves out in the buffer solution, hence, detected electrochemically using Differential Pulse Voltammetric (DPV) technique. The sensing matrix is characterised using FT-IR and Raman spectroscopy. Transmission Electron Microscopy is carried out to study the morphology of functionalized graphene sheets.

Electrical pulse-induced electrochemical biosensor for hepatitis E virus detection

The good stability, low cytotoxicity, and excellent photoluminescence property of graphene quantum dots (GQDs) make them an emerging class of promising materials in various application fields ranging from sensor to drug delivery. In the present work, the dopamine-functionalized GQDs (DA-GQDs) with stably bright blue fluorescence were successfully synthesized for low level Fe3+ ions detection.