Browsing by Author "Anchal Srivastava"

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2D materials for flexible electronics
(Elsevier, 2022) Suyash Rai; Himanshu Mishra; Vijay K Singh; Tejendra K Gupta; Anchal Srivastava
Since the breakthrough of graphene, two-dimensional (2D) materials have attracted immense research interest due to their unique electronic, optical, and mechanical properties, holding great potential for harnessing their applications in next-generation electronics, optoelectronics, and biomedical fields. The most striking feature of 2D materials is their atomic thickness, which makes them feasible to adhere to any kind of surface without losing much of their inherent properties. With this advantage, 2D materials can be integrated into various flexible and stretchable electronic devices in a conventional and scalable fashion. Here in this chapter the synthesis of 2D materials using different top-down and bottom-up methods followed by various efficient transfer methods has been discussed thoroughly. After that, state-of-the-art flexible device applications of 2D materials in electronics, sensors, and energy storage devices, along with their future possibilities, are discussed. © 2023 Elsevier Ltd. All rights reserved.
2D SnS2 Nanostructure-Derived Photocatalytic Degradation of Organic Pollutants Under Visible Light
(Frontiers Media S.A., 2021) Rohit Ranjan Srivastava; Pramod Kumar Vishwakarma; Umakant Yadav; Suyash Rai; Sima Umrao; Rajiv Giri; Preeti Suman Saxena; Anchal Srivastava
Wastewater produced by the textile industry contains various dyes and organic compounds that directly or indirectly affect surface water or groundwater pollution. Visible-light-driven semiconductor photocatalysis is the leading pathway for the degradation of environmental pollutants. Herein we report the bottom-up hydrothermal growth of 2D tin disulfide nanostructures (SnS2 NSs) for the efficient photodegradation of organic pollutants such as Rhodamine B (Rh.B) and Methyl Violet (M.V) in an aqueous medium under visible light (λ > 400 nm) irradiation. The as-synthesized SnS2 NSs were characterized by various structural, morphological, and optical techniques such as XRD, RAMAN, TEM, UV–Vis, Brunauer–Emmett–Teller, etc. Furthermore, the low bandgap (∼1.6 eV), the high surface area (56 m2/g), and the anionic nature of SnS2 NSs attribute to it as an efficient photocatalyst for photocatalytic applications. The photocatalytic properties of SnS2 NSs showed good degradation efficiency of 94 and 99.6% for Rh. B and M.V, respectively, in 25 min. The kinetic rate constant of these dyes was estimated by using the Langmuir–Hinshelwood model. Here we also performed the recyclability test of the photocatalyst and discussed the plausible mechanism for the photocatalytic degradation of organic pollutants. The XPS spectra of SnS2 NSs were studied before and after the photodegradation of Rh.B and M.V, indicating the high stability of the photocatalyst. Moreover, in vitro cytotoxicity was also evaluated against human cervical cancer cell lines (HeLa cells) with different concentrations (0–1,000 μg/ml) of as-synthesized SnS2 NSs. This intended work provides a possible treatment for the degradation of organic pollutants under visible light to balance the aquatic ecosystems. Copyright © 2021 Srivastava, Kumar Vishwakarma, Yadav, Rai, Umrao, Giri, Saxena and Srivastava.
A comparative study of band gap engineered in-situ and ex-situ MWCNTs/TiO2 heterostructures for their enhanced photocatalytic activity under visible light
(Elsevier B.V., 2023) Anshu Kumar Singh; Pramod Kumar Vishwakarma; Sumit Kumar Pandey; Raghvendra Pratap; Rajiv Giri; Anchal Srivastava
Organic pollutants, such as various types of organic dyes coming out from the textile industries, are polluting surface and groundwater resources alarmingly and posing a threat to aquatic ecosystems. So, the demand for visible-light-driven high-performance photocatalysts having high activity and structural stability is a need of an hour. TiO2 has been one of the well-known and most studied semiconductor photocatalysts for decades. But its low electron-hole pair (e-/h+) recombination time reduces its efficiency, and the large band gap restricts its use as a visible-light-driven photocatalyst. To overcome these limitations of TiO2, herein, we have reported an in-situ and ex-situ MWCNTs modified TiO2 heterostructure nanocomposites photocatalyst and established a comparative study in terms of their ability to degrade methylene blue (MB) dye under visible light irradiation. The as-synthesized in-situ CNTs-TiO2 nanocomposite and ex-situ CNTs-TiO2 nanocomposite were characterized structurally, morphologically, compositionally, and optically through various characterization techniques such as XRD, RAMAN, SEM, XPS, FTIR, and UV–Vis diffuse reflectance spectroscopy. The result reveals the band gap tuning in the in-situ and ex-situ CNTS-TiO2 nanocomposites as a result of increasing MWCNTs concentration. The in-situ CNTs-TiO2-2 nanocomposite has high degradation efficiency (94% in 150 min) and stability due to smooth and strong chemical interactions between the MWCNTs and TiO2, while ex-situ CNTs-TiO2-20 with 10 times more MWCNTs concentration (by weight) as compared to MWCNTs concentration in in-situ CNTs-TiO2-2, exhibits degradation efficiency of 89% in 150 min. The possible degradation mechanism to degrade MB dye has also been put forward. © 2023
A comprehensive review on graphene-based materials as biosensors for cancer detection
(Oxford University Press, 2023) Rim M. Alsharabi; Suyash Rai; Hamed Y. Mohammed; Maamon A. Farea; Sesha Srinivasan; Preeti S. Saxena; Anchal Srivastava
Nowadays, cancer is increasingly becoming one of the foremost threats to human being life worldwide, and diagnosing this deadly disease is one of the major priorities of researchers. Described as a monolayer-thin-sheet of hexagonally patterned carbon atoms, ‘graphene’ is considered an innovative evergreen carbon material ideal for a wide array of sensing applications and nanotechnologies. Graphene-based materials (GBMs) have acquired a huge share of interest in the scope of biosensor fabrication for early and accurate cancer diagnosis. Herein, we have insights reviewed the various routes and technologies for synthesized graphene, and GBMs including 3D graphene (i.e. hydrogels, foams, sponges and porous) and 0D graphene (i.e. quantum dots). Moreover, we have introduced the different types of graphene/GBMs biosensors (i.e. electrochemical biosensors, optical biosensors, field-effect transistors biosensors, electrochemiluminescence biosensors and microfluidics biosensors) and their merits and applications for cancer prestage detection. © The Author(s) 2022. Published by Oxford University Press.
A curious observation of Pauli-Blocking in MoS2-quantum dots/graphene hybrid system
(American Institute of Physics Inc., 2018) Amulya Nemoori; Himanshu Mishra; Vijay Kumar Singh; P.K. Shukla; Anchal Srivastava; Amritanshu Pandey
In this study, Pauli-Blocking has been observed in a 0D/2D MoS2 quantum dots/graphene (MoS2-QDs/graphene) hybrid system. For the observation of room temperature Pauli-Blocking in the 0D/2D system, a photodetector device based on n-type MoS2-QDs and CVD grown graphene has been fabricated using a facile and lithography free technique. The current-voltage characteristics of the device have been performed at room temperature. The fabricated device shows a negative response under visible light (λ ∼ 400 to 700 nm) illumination. The dark to photo current ratio of the device shows variation up to two orders of magnitude. This negative response, which results decrease in current under visible light illumination, may be attributed to the Pauli-Blocking due to high absorbance of photon energy in visible light range. Furthermore, it is believed that the present study may provide an insight into understanding the Pauli-Blocking in 0D/2D hybrid system at room temperature. © 2018 Author(s).
A Lithography-Free Fabrication of Low-Operating Voltage-Driven, Very Large Channel Length Graphene Field-Effect Transistor with NH3Sensing Application
(Institute of Electrical and Electronics Engineers Inc., 2020) Nitesh K. Chourasia; Abhishek Kumar Singh; Suyash Rai; Anand Sharma; P. Chakrabarti; Anchal Srivastava; Bhola N. Pal
Large-area-based field-effect transistor (FET) gas sensor has the potential to provide a larger sensing area for a chemical analyte. So far, graphene FETs (GFETs) are mostly fabricated by expensive lithographic techniques with a minimum channel length. We have demonstrated a simple way to fabricate a very large channel length of 0.45 mm GFET using ion-conducting dielectric with thermally evaporate source/drain electrodes and has been demonstrated for an application of ambient atmosphere ammonia gas sensing. Ion-conducting Li5AlO4 gate dielectric has reduced operating voltage up to 2.0 V with good current saturation. The chemical vapor deposition (CVD) grown uniform monolayer of graphene has been used as an active channel layer of FET. The fabricated device has been tested for different concentrations of ammonia in ambient environment conditions at 25 °C temperature, which indicates that the Dirac point voltage of the device varies up to 0.8 V when the concentration of ammonia has been changed from 0 to 3 ppm. Moreover, this study also reveals that this GFET is capable of detecting ammonia up to the concentration level of 0.1 ppm. © 1963-2012 IEEE.
A novel approach for rapid and sensitive detection of Zika virus utilizing silver nanoislands as SERS platform
(Elsevier B.V., 2023) Manish Nath Tripathi; Poonam Jangir; Aakriti; Suyash Rai; Mayank Gangwar; Gopal Nath; Preeti S. Saxena; Anchal Srivastava
To control the spread of the disease, the Zika virus (ZIKV), a flavivirus infection spread by mosquitoes and common in across the world, needs to be accurately and promptly diagnosed. This endeavour gets challenging when early-stage illnesses have low viral loads. As a result, we have created a biosensor based on surface-enhanced Raman scattering (SERS) for the quick, accurate, and timely diagnosis of the Zika virus. In this study, a glass coverslip was coated with silver nanoislands, which were then utilized as the surface for creating the sensing platform. Silver nanoislands exhibit strong plasmonic activity and good conductive characteristics. It enhances the Raman signals as a result and gives the SERS platform an appropriate surface. The created platform has been applied to Zika virus detection. With a limit of detection (LOD) of 0.11 ng/mL, the constructed sensor exhibits a linear range from 5 ng/mL to 1000 ng/mL. Hence, even at the nanogram scale, this technique may be a major improvement over clinical diagnosis approaches for making proper, precise, and accurate Zika virus detection. © 2023 Elsevier B.V.
A possible mechanism for the emergence of an additional band gap due to a Ti-O-C bond in the TiO2-graphene hybrid system for enhanced photodegradation of methylene blue under visible light
(Royal Society of Chemistry, 2014) Sima Umrao; Shiju Abraham; Frank Theil; Shobhit Pandey; Valerian Ciobota; P.K. Shukla; Caroline J. Rupp; Sudip Chakraborty; Rajeev Ahuja; Jürgen Popp; Benjamin Dietzek; Anchal Srivastava
Here we report the experimental and theoretical study of two TiO2-graphene oxide (TG) and TiO2-reduced graphene oxide (TR) composites synthesized by a facile and ecological route, for enhanced visible light (∼470 nm) photocatalytic degradation of Methylene Blue (MB) (99% efficiency), with high rate constant values (1800% over bare TiO2). TG couples TiO2 nanopowder with Graphene Oxide (GO) while TR couples it with reduced graphene oxide (RGO). The present study, unlike previous reports, discusses never-before-reported double absorption edges obtained for both TG (3.51 eV and 2.51 eV) and TR (3.42 eV and 2.39 eV) composites, which represents the reason behind feasible visible light (2.56 eV) induced photocatalysis. TiO2 domains in the composites dominate the higher band edge, while GO/RGO domains explain the lower band edge. Formation of Ti-O-C bonds in both TG and TR drives the shifting upwards of the valence band edge and reduction in band gap. Further, these bonds provide a conductive pathway for charge carriers from TiO2 nanopowder to the degraded species via the GO/RGO matrix, resulting in decreased charge carrier recombination in TiO2 and enhanced efficiency. To attest that the developed theory is correct, density function theory (DFT) calculations were performed. DFT obtained energetics and electronic structures support experimental findings by demonstrating the role of the Ti-O-C bond, which results in double band edge phenomenon in composites. Finally, the mechanism behind MB degradation is discussed comprehensively and the effect of the weight percent of GO/RGO in the composite on the rate constant and photodegradation efficiency has been studied experimentally and explained by developing analytical equations. © The Royal Society of Chemistry 2014.
A review on advanced nanoengineered biomaterials for chronic wound healing
(Springer Nature, 2023) Sujit Yadav; Aakriti Prakash; Umakant Yadav; P.S. Saxena; Anchal Srivastava
Diabetes mellitus is a complex chronic metabolic disease that has a negative impact on patient health as well as creates a significant financial strain on healthcare systems worldwide. An unregulated molecular and cellular wound microenvironment and persistent inflammation are characteristics of chronic diabetic ulcers. Films, antimicrobial dressings, hydrogels, foams, and other biomaterials have all found uses in wound treatment. Despite many studies, there is still no “perfect” therapy for chronic wound healing, and complexities have been addressed. In this paper, we discuss the present difficulties associated with the production of biomaterials for the management and treatment of chronic wounds. Which includes a wide range of important biomaterials and their composites that accelerate angiogenesis, inhibit bacterial infection, collagen matrix deposition, and wound closure. This review also highlights other factors like oxygenation, hormones, obesity, medications, smoking, and nutrition. Finally, the future directions of biomaterials for chronic wound healing are discussed. © 2023, Indian National Science Academy.
A review on recent progress in synthesis, properties, and applications of MXenes
(Oxford University Press, 2025) Ashish Jyoti Borah; Varun Natu; Abhijit Biswas; Anchal Srivastava
MXenes, a noble class of two-dimensional (2D) material, discovered in 2011 have gained attention in recent years. They have attracted significant attention due to their flexible elemental composition, distinctive 2D-layered architecture, large surface area, and abundant surface terminations. Top-down synthesis techniques such as HF etching, alkaline etching, and electrochemical methods are used for MXene synthesis. Alongside these methods, methods like chemical vapor deposition (CVD), template method and plasma enhanced pulsed layer deposition (PELPD) are also used for the thin-film synthesis of MXenes. The discovery of double transition-metal layered MXene, solid, and high entropy MXene open up the prospect of further novel structures. MXenes are electrically conductive and have promising optoelectronic, mechanical, and thermoelectric properties. MXenes have also shown immense potential in biomedicine and environmental applications. The surface chemistry of MXene make them ideal for biosensors, drug delivery, and photothermal therapy, while their photocatalytic and adsorption properties enable efficient removal of pollutants and contaminants from water. This review examines the various MAX phase synthesis methods, such as solid-state reactions, hot isostatic pressing, and spark plasma sintering, followed by top-down techniques like HF etching, alkaline etching, and electrochemical etching, as well as bottom-up methods like CVD, template approaches, and plasma-enhanced pulsed layer deposition. The review also looks into the optical, chemical, and electronic properties of MXene, as well as their advancements in energy storage, optoelectronics, pollution avoidance, biomedical applications, and more. © 2024 The Author(s).
A self assembled monolayer based microfluidic sensor for urea detection
(2011) Saurabh Srivastava; Pratima R. Solanki; Ajeet Kaushik; Md. Azahar Ali; Anchal Srivastava; B.D. Malhotra
Urease (Urs) and glutamate dehydrogenase (GLDH) have been covalently co-immobilized onto a self-assembled monolayer (SAM) comprising of 10-carboxy-1-decanthiol (CDT) via EDC-NHS chemistry deposited onto one of the two patterned gold (Au) electrodes for estimation of urea using poly(dimethylsiloxane) based microfluidic channels (2 cm × 200 μm × 200 μm). The CDT/Au and Urs-GLDH/CDT/Au electrodes have been characterized using Fourier transform infrared (FTIR) spectroscopy, contact angle (CA), atomic force microscopy (AFM) and electrochemical cyclic voltammetry (CV) techniques. The electrochemical response measurement of a Urs-GLDH/CDT/Au bioelectrode obtained as a function of urea concentration using CV yield linearity as 10 to 100 mg dl-1, detection limit as 9 mg dl -1 and high sensitivity as 7.5 μA mM-1 cm-2. © 2011 The Royal Society of Chemistry.
Atomic layers of hybridized boron nitride and graphene domains
(Nature Publishing Group, 2010) Lijie Ci; Li Song; Chuanhong Jin; Deep Jariwala; Dangxin Wu; Yongjie Li; Anchal Srivastava; Z.F. Wang; Kevin Storr; Luis Balicas; Feng Liu; Pulickel M. Ajayan
Two-dimensional materials, such as graphene and monolayer hexagonal BN (h-BN), are attractive for demonstrating fundamental physics in materials and potential applications in next-generation electronics. Atomic sheets containing hybridized bonds involving elements B, N and C over wide compositional ranges could result in new materials with properties complementary to those of graphene and h-BN, enabling a rich variety of electronic structures, properties and applications. Here we report the synthesis and characterization of large-area atomic layers of h-BNC material, consisting of hybridized, randomly distributed domains of h-BN and C phases with compositions ranging from pure BN to pure graphene. Our studies reveal that their structural features and bandgap are distinct from those of graphene, doped graphene and h-BN. This new form of hybrid h-BNC material enables the development of bandgap-engineered applications in electronics and optics and properties that are distinct from those of graphene and h-BN. © 2010 Macmillan Publishers Limited. All rights reserved.
Autonomous self-optimizing defects by refining energy levels through hydrogenation in CeO2-x polymorphism: a walking mobility of oxygen vacancy with enhanced adsorption capabilities and photocatalytic stability
(Royal Society of Chemistry, 2022) Ranjana Verma; Jay Singh; Sanjoy Kumar Samdarshi; Anchal Srivastava
We approach a self-consistent technique to enhance solar absorption by a proper balance of trapping sites through hydrogenation. Understanding the impact of hydrogenation on oxygen vacancy sites in CeO2 is crucial in improving the photocatalytic performance of a catalyst. This unique method paves the way to control surface defects, size, and core/shell thickness through the manipulation of surface defects. A large content of defects has a detrimental influence on partially reduced CeO2−x and causes a deterioration in the performance of the catalyst. Therefore, rational optimization of defects on the surface is of paramount importance. The study was carried out using a multi-technique characterization tools such as XRD, HRTEM, UV-vis, XPS, Raman, PL and FTIR studies. Two important benefits can be gained from this work. First, band-gap reduction does not ensure substantial enhancement of photocatalytic activity as band-gap renormalization occurs after hydrogenation. Second, non-stoichiometric Ce3+ is optimized through mobility of oxygen vacancies. This work opens a new door to moving non-stoichiometric CeO2−x close to ordered CeO2 by refining energy levels through hydrogenation. © 2022 The Royal Society of Chemistry
Biofunctional magnetic nanotube probe for recognition and separation of specific bacteria from a mixed culture
(Royal Society of Chemistry, 2013) Vinod Kumar; Gopal Nath; Ravinder. K. Kotnala; Preeti S. Saxena; Anchal Srivastava
This study highlights the synthesis of an antibody conjugated magnetic carbon nanotube bioprobe for the recognition and separation of Pseudomonas aeruginosa (P. aeruginosa), a gram negative bacterium, from its mixed culture with Staphylococcus aureus (S. aureus). Multiwalled carbon nanotubes containing iron oxide nanoparticles (magnetic carbon nanotubes) were synthesized in a single step by a spray pyrolysis method. The synthesized magnetic nanotubes were characterized by X-ray diffraction, electron microscopy and magnetic property measurements. A P. aeruginosa specific rhodamine-labelled goat anti-Pseudomonas antibody was covalently attached to the magnetic carbon nanotubes to develop a bioprobe. Raman and Fourier transform spectroscopy studies were carried out to confirm the attachment of the antibodies to the magnetic nanotubes. The designed bioprobe was employed for the capture and subsequent separation of P. aeruginosa from its mixed culture with S. aureus. The probing efficiency of the developed bioprobe was characterized and confirmed by culturing the captured P. aeruginosa in selective media followed by fluorescence and scanning electron microscopy studies. A time dependent increase in the capture efficiency of the bioprobe for P. aeruginosa was noticed and found to be 65% within five minutes of incubation. Thus, the designed bioprobe presents a simple, reliable and cost effective diagnostic tool for rapid identification and separation of a particular bacterium from a site of co-infection which is of immense clinical relevance. © The Royal Society of Chemistry 2013.
Bioinspired synthesis of silver nanoparticles
(S.C. Virtual Company of Phisics S.R.L, 2009) Upendra Kumar Parashar; Preeti S. Saxena; Anchal Srivastava
Disease-causing microbes that have become resistant to drug therapy are an increasing public health problem. Therefore there is an urgent need to develop new bactericides. Silver nanoparticles are the metal of choice as they hold the promise to kill microbes effectively. Silver nanoparticles take advantages of the oligodynamic effect that silver has on microbes. In this work we have synthesized silver nanoparticles using environmentally benign material like Mentha Piperita leaf extract. In the process of synthesizing silver nanoparticles we observed a rapid reduction of silver ions leading to the formation of stable crystalline silver nanoparticles in the solution. Transmission electron microscopy and UV-Vis Spectroscopy analysis of these particles shows that they are ranged in size from 5 nm to 30 nm.
Biotene: Earth-Abundant 2D Material as Sustainable Anode for Li/Na-Ion Battery
(American Chemical Society, 2024) Atin Pramanik; Preeti Lata Mahapatra; Raphael Tromer; Jianan Xu; Gelu Costin; Chenxi Li; Sreehari Saju; Salma Alhashim; Kavita Pandey; Anchal Srivastava; Robert Vajtai; Douglas S. Galvao; Chandra Sekhar Tiwary; Pulickel M. Ajayan
Natural ores are abundant, cost-effective, and environmentally friendly. Ultrathin (2D) layers of a naturally abundant van der Waals mineral, Biotite, have been prepared in bulk via exfoliation. We report here that this 2D Biotene material has shown extraordinary Li-Na-ion battery anode properties with ultralong cycling stability. Biotene shows 302 and 141 mAh g-1 first cycle-specific charge capacity for Li- and Na-ion battery applications with ∼90% initial Coulombic efficiency. The electrode exhibits significantly extended cycling stability with ∼75% capacity retention after 4000 cycles even at higher current densities (500-2000 mA g-1). Further, density functional theory studies show the possible Li intercalation mechanism between the 2D Biotene layers. Our work brings new directions toward designing the next generation of metal-ion battery anodes. © 2024 American Chemical Society.
Carbon nanostructure (0-3 dimensional) supported isolated gold nanoparticles as an effective SERS substrate
(Elsevier B.V., 2018) Shiju Abraham; Matthias König; Sunil K. Srivastava; Vinod Kumar; Bernd Walkenfort; Anchal Srivastava
The present work reports a comparative surface enhanced Raman scattering (SERS) study of nanohybrids of spatially isolated gold nanoparticles (Au NPs) with different carbon nanostructures (CNS). For a meticulous comparative analysis, different CNS covering from zero dimensional to three dimensions were used. SERS activities of developed nanohybrids platforms were evaluated with a Raman marker i.e. Mercaptobenzoic acid (4-MBA, 1 μM). Synergistic Raman signal enhancement from each Au NP (electromagnetic enhancement) and underlying CNS matrix (chemical enhancement) was observed in nanohybrid enabling detection of very small concentration of 4-MBA i.e. 1 μM convincingly. Among the different underlying matrix, GQDs-Au NPs based SERS platform have shown highest SERS enhancement by a factor of 107, followed by GO-Au NPs combination (∼ 3 × 106) and others. Enhanced SERS activity of GQDs -Au NPs -4-MBA nanohybrid platform is attributed to the D and G bands of GQDs, overpowering the strong fluorescent background of GQDs alone. Reported nanohybrids; specially GQDs-Au NPs offers numerous possibilities to be used as sensitive and reproducible SERS platform for the detection of other biologically/chemically important analytes, showing potential for standardization in near future. © 2018 Elsevier B.V.
Carbon nanotube membrane filters
(Springer Berlin Heidelberg, 2013) Anchal Srivastava; Saurabh Srivastava; Kaushik Kalaga
This chapter provides an overview of different filtration processes (Sect. 31.1) and the mechanism of nanofiltration (Sect. 31.2). In the following sections, we focus on nanofiltration based on carbon nanotube membranes. A brief introduction to carbon nanotubes and their structure and properties is given, with an emphasis on the different kinds of synthesis of membranes; their function in nanofiltration in gas–vapor transport, liquid transport, and some other filtration-like techniques for filtration of bacteria and viruses is also discussed in detail (Sect. 31.3). Finally, an outlook of future research is proposed. © Springer-Verlag Berlin Heidelberg 2013.
Carbon nanotubes molybdenum disulfide 3D nanocomposite as novel nanoscaffolds to immobilize Lens culinaris β-galactosidase (Lsbgal): Robust stability, reusability, and effective bioconversion of lactose in whey
(Elsevier Ltd, 2019) Anjali Yadav; Sumit Kumar Pandey; Dinesh Chand Agrawal; Himanshu Mishra; Anchal Srivastava; Arvind M. Kayastha
Multiwalled carbon nanotubes molybdenum disulfide 3D nanocomposite (MWCNT-MoS2 NC) was successfully synthesized via eco-friendly hydrothermal method. The microstructural characterization of synthesized nanocomposite was carried out using different spectroscopic and microscopic techniques. Nanocomposite was activated using glutaraldehyde chemistry and used as a platform to immobilize Lens culinaris β-galactosidase (Lsbgal) which resulted in 93% of immobilization efficiency. Attachment of Lsbgal onto nanocomposite was confirmed by AFM, FE-SEM, FTIR, and CLSM. The nanobiocatalyst showed broadening in operational pH and temperature working range. Remarkable increase in thermal stability was observed as compared to soluble enzyme. Nanobiocatalyst showed outstanding increase in storage stability, retained 92% of residual activity over a period of 8 months. This offers good reusability as it retained ∼50% residual activity up to 21 reuses and exhibited higher rate of lactose hydrolysis in whey. MWCNT-MoS2 NC conjugated to biomolecules can serve as a potential platform for fabrication of lactose biosensor. © 2019 Elsevier Ltd
Carboxylated multiwalled carbon nanotubes based biosensor for aflatoxin detection
(2013) Chandan Singh; Saurabh Srivastava; Md. Azahar Ali; Tejendra K. Gupta; Gajjala Sumana; Anchal Srivastava; R.B. Mathur; Bansi D. Malhotra
We report results of studies relating to the development of an electrochemical immunosensor based on carboxylated multiwalled carbon nanotubes (c-MWCNTs) electrophoretically deposited onto indium tin oxide (ITO) glass. This c-MWCNTs/ITO electrode surface has been functionalized with monoclonal aflatoxin B1 antibodies (anti-AFB1) for the detection of aflatoxin-B1 using electrochemical technique. Electron microscopy, X-ray diffraction and Raman studies suggest successful synthesis of c-MWCNTs and the Fourier transform infra-red spectroscopic (FT-IR) studies reveal its carboxylic functionalized nature. The proposed immunosensor shows high sensitivity (95.2 μA ng-1 mL cm-2), improved detection limit (0.08 ng mL-1) in the linear detection range of 0.25-1.375 ng mL-1. The low value of association constant (0.0915 ng mL -1) indicates high affinity of immunoelectrode towards aflatoxin (AFB1). © 2013 Elsevier B.V.