Browsing by Author "Preeti S. Saxena"

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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 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.
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.
Cefuroxime axetil loaded solid lipid nanoparticles for enhanced activity against S. aureus biofilm
(Elsevier, 2014) Bhupender Singh; Parameswara Rao Vuddanda; Vijayakumar M.R.; Vinod Kumar; Preeti S. Saxena; Sanjay Singh
The present research work is focused on the development of solid lipid nanoparticles of cefuroxime axetil (CA-SLN) for its enhanced inhibitory activity against Staphylococcus aureus produced biofilm. CA-SLN was prepared by solvent emulsification/evaporation method using single lipid (stearic acid (SA)) and binary lipids (SA and tristearin (TS)). Process variables such as volume of dispersion medium, concentration of surfactant, homogenization speed and time were optimized. The prepared SLN were characterized for encapsulation efficiency, drug polymer interaction studies (DSC and FT-IR), shape and surface morphology (SEM and AFM), in vitro drug release, stability studies and in vitro anti biofilm activity against S. aureus biofilm. Among the process variables, increased volume of dispersion medium, homogenization speed and time led to increase in particle size whereas increase in surfactant concentration decreased the particle size. SLN prepared using binary lipids exhibited higher entrapment efficiency than the single lipid. DSC and FT-IR studies showed no incompatible interaction between drug and excipients. CA-SLN showed two folds higher anti-biofilm activity in vitro than pristine CA against S. aureus biofilm. © 2014 Elsevier B.V.
Colorimetric detection of cholesterol based on enzyme modified gold nanoparticles
(Elsevier B.V., 2018) Narsingh R. Nirala; Preeti S. Saxena; Anchal Srivastava
We develop a simple colorimetric method for determination of free cholesterol in aqueous solution based on functionalized gold nanoparticles with cholesterol oxidase. Functionalized gold nanoparticles interact with free cholesterol to produce H2O2 in proportion to the level of cholesterol visually is being detected. The quenching in optical properties and agglomeration of functionalized gold nanoparticles play a key role in cholesterol sensing due to the electron accepting property of H2O2. While the lower ranges of cholesterol (lower detection limit i.e. 0.2 mg/dL) can be effectively detected using fluorescence study, the absorption study attests evident visual color change which becomes effective for detection of higher ranges of cholesterol (lower detection limit i.e. 19 mg/dL). The shades of red gradually change to blue/purple as the level of cholesterol detected (as evident at 100 mg/dL) using unaided eye without the use of expensive instruments. The potential of the proposed method to be applied in the field is shown by the proposed cholesterol measuring color wheel. © 2017 Elsevier B.V.
Colorimetric detection of cholesterol based on highly efficient peroxidase mimetic activity of graphene quantum dots
(Elsevier, 2015) Narsingh R. Nirala; Shiju Abraham; Vinod Kumar; Anushka Bansal; Anchal Srivastava; Preeti S. Saxena
In the present study, we report graphene quantum dots (GQDs), an enzyme mimetic of horse radish peroxidase (HRP), for unprecedented detection of free cholesterol. Synthesized directly from graphite using simple and quick one step wet chemical method, these GQDs in the presence of H2O2 exhibit highly efficient catalytic activity toward the oxidation of peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) to produce a blue colored product. The proposed detection system based on GQDs allows wide range (0.02-0.6 mM) of cholesterol sensing with a detection limit as low as 0.006 mM. Further, higher Vmax (7.3 × 10-6 M s-1) along with lower Km (0.01 mM) attest enhanced peroxidase like catalytic activity and better binding affinity of cholesterol oxidase (ChOx) to cholesterol resulting in good biosensor stability and resistance to environmental interferences. The proposed method without the use of sophisticated instruments perceives the cholesterol using naked eye with blue color compound formation. The potential of the method to be applied on field is shown by the proposed cholesterol measuring color wheel, where the shades of color are related to actual levels of cholesterol in the sample. © 2015 Published by Elsevier B.V.
Development of folate-conjugated polypyrrole nanoparticles incorporated with nitrogen-doped carbon quantum dots for targeted bioimaging and photothermal therapy
(Elsevier B.V., 2024) Aakriti Prakash; Sujit Yadav; Preeti S. Saxena; Anchal Srivastava
PPy nanoparticles are widely employed as PTT agents, because of their exceptional near-infrared absorption properties. Nonetheless, the efficacy of PTT with PPy nanoparticles is hindered by a challenge, specifically, a lack of precise targeting. In this study, a PTT imaging agent was developed by combining NCQDs having bright green fluorescent properties with PPy nanoparticles along with the masking of folic acid to overcome the challenge of targeting. The synthesized PPy:NCQDs:FA nanocomposite, characterized by extraordinary photothermal property, was utilized for imaging of folate receptor positive (FA+) MCF-7 cancer cells through the emission of green fluorescence by NCQDs incorporated within the nanocomposite. Additionally, these nanoparticles demonstrated a good level of cell viability, exceeding 82 %, even at a concentration of 600 μg mL−1. Even the in vivo toxicity inspection of the nanocomposite exemplified no observed acute toxicity at experimental dosages of 1 and 3 mg per kg body weight. By subjecting MCF-7 cells, inoculated with 100 μg mL−1 of nanocomposite, to NIR laser irradiation for 5 min, a significant decline in cell viability was witnessed, establishing the photothermal therapeutic potency of the nanocomposite. The death of cancer cells induced by nanocomposite was verified through MTT assay, imaging of cells by NCQDs alone, with nanocomposite, and by live/dead cell Calcein AM/PI staining assay. Quantification of induced apoptosis post-laser treatment is conducted through staining with Annexin V-FITC/PI. These findings establish potential use of PPy:NCQDs:FA nanocomposite as versatile theranostic agents, capable of targeted bioimaging and treatment for cancer cells exhibiting folate receptors. © 2024 Elsevier B.V.
Different shades of cholesterol: Gold nanoparticles supported on MoS2 nanoribbons for enhanced colorimetric sensing of free cholesterol
(Elsevier Ltd, 2015) Narsingh R. Nirala; Shobhit Pandey; Anushka Bansal; Vijay K. Singh; Bratindranath Mukherjee; Preeti S. Saxena; Anchal Srivastava
In the present study, we manifest that traditionally used gold nanoparticles when supported on molybdenum disulfide nanoribbons matrix (MoS2 NRs-Au NPs) show synergistically enhanced intrinsic peroxidase like catalytic activity and can catalyze the oxidation of 3,3',5,5' tetramethyl benzidine by H2O2 to produce a highly sensitive blue shade product depending on level of free cholesterol, when tested on complex system of human serum. Further the system attests appreciable kinetics, owing to Km value as low as 0.015mM and better loading capacity (Vmax=6.7×10-6Ms-1). Additionally, the proposed system is stable for weeks with ability to perform appreciably in wide pH (3-6) and temperature range (25-60°C). Utilizing this potential, the present work proposes a cholesterol detection color wheel which is used along with cost effective cholesterol detection strips fabricated out of proposed MoS2 NRs-Au NPs system for quick and reliable detection of free cholesterol using unaided eye. © 2015 Elsevier B.V.
Ecotoxic impact assessment of graphene oxide on lipid peroxidation at mitochondrial level and redox modulation in fresh water fish Anabas testudineus
(Elsevier Ltd, 2019) Biswaranjan Paital; Deeptimayee Guru; Priyadarsini Mohapatra; Biswajit Panda; Nibedita Parida; Sasmita Rath; Vinod Kumar; Preeti S. Saxena; Anchal Srivastava
Rapidly expanding nanoparticle industries are predicted to have turnover of ∼$173.95 billion by 2025, indicating an urgency to study their comprehensive toxicological impact(s). Toxic effects of Graphene Oxide (GO) on oxidative stress physiology especially at mitochondrial level and redox modulation in fish in general and in climbing perch Anabas testudineus is absent. Therefore, we have investigated the toxic impacts of sub lethal doses of GO on selected oxidative stress physiology markers, protein and nucleic acid content along with haematological parameters in A. testudineus. Discriminant function and correlation analyses suggest that GO had toxic effects on the fish, as revealed from the studied parameters. Liver and gill tissues had shown strong response to GO than muscle. Augmented gradual accumulation of cellular lipid peroxides, specifically in mitochondria, was noticed. Activity of superoxide dismutase, catalase, and glutathione-S-transferase was augmented in contrast to the lowered level of the reduced glutathione titre. Alleviated total red blood corpuscle count and haemoglobin titre was parallel with an augmentation of white blood corpuscle count under GO administration. The protein level was also alleviated gradually in liver with clear changes in tissue specific nucleic acid levels, which was reduced under GO treatment. Results of the present study indicate that GO induces oxidative stress in cell and mitochondria in fish. Therefore, very careful future practices of use of GO directly, or as cargo in environmental monitoring processes in aquatic models in vitro in general and Pisces model in particular are suggested. © 2019 Elsevier Ltd
Enhanced electrochemical biosensing efficiency of silica particles supported on partially reduced graphene oxide for sensitive detection of cholesterol
(Elsevier B.V., 2015) Shiju Abraham; Saurabh Srivastava; Vinod Kumar; Shobhit Pandey; Pankaj Kumar Rastogi; Narsingh R. Nirala; Sunayana Kashyap; Sunil K. Srivastava; Vidya Nand Singh; Vellaichamy Ganesan; Preeti S. Saxena; Anchal Srivastava
The present work introduces partially reduced graphene oxide (pRGO)-silica (SiO2) particles hybrid system (pRGOSHs) for sensitive and cost effective free cholesterol detection. Fabricated out of thin layers of pRGOSHs, these proposed ChOx/pRGOSHs/ITO based biosensors have a detection range of 2.6-15.5 mM with an appreciable detection limit of 1.3 mM and sensitivity of 11.1 μA/mM/cm2. Low Michaelis-Menten constant (Km) (4.9 × 10- 4 mM) and high diffusivity constant (D) (3.2 × 10- 10 cm2/s) values clearly indicate enhanced immobilization of enzyme over the substrate. Additionally, electrochemical impedance studies indicate that the synergistic combination of SiO2 and pRGO also results in much lower impedance values (40% and 18% decrease in comparison to SiO2 and pRGO respectively) for an overall enhanced sensing performance. These results are further corroborated by the density functional theory based theoretical simulations indicating enhanced electron density (theoretically) in case of the proposed hybrid system. Finally, the present work also highlights the importance of Si-OH bonds formation in the proposed pRGOSHs composite system for attaining such enhanced biosensing ability. © 2015 Elsevier B.V.
Enhanced Osteogenesis by Molybdenum Disulfide Nanosheet Reinforced Hydroxyapatite Nanocomposite Scaffolds
(American Chemical Society, 2019) Umakant Yadav; Himanshu Mishra; Vimal Singh; Sunayana Kashyap; Anchal Srivastava; Sanjay Yadav; Preeti S. Saxena
The advances in the arena of biomedical engineering enable us to fabricate novel biomaterials that provide a suitable platform for rapid bone regeneration. Herein, we have investigated the in vitro and in vivo osteogenic differentiation, proliferation, and bone regeneration capability of molybdenum disulfide nanosheets (MoS2NSs) reinforced HAP nanocomposite scaffolds. The MG-63 cells were incubated with HAP and HAP/MoS2NSs nanocomposite and followed for various cellular activities. The cells incubated with HAP@2 shows higher cell adhesion, cell proliferation, and alkaline phosphatase activity (ALP) in contrast to HAP. The in vivo and in vitro results of the increased ALP level confirm that HAP@2 promotes osteogenic differentiation. This improved osteogenesis was validated with upregulation of osteogenic marker viz. transcription factor, RUNX-2 (∼34 fold), collagen-1 (∼15 fold), osteopontin (∼11 fold), osteocalcin (∼20 fold), and bone morphogenetic protein-2 (∼12 fold) after 12 week postimplantation in comparison to drilled. The X-ray imaging demonstrates that HAP@2 implants promote rapid osteogenesis and bioresorbability than HAP and drilled. The outcomes of the present study provide a promising tool for the regeneration of bone deformities, without using any external growth factor. © 2019 American Chemical Society.
Facile synthesis of highly fluorescent nitrogen-doped carbon quantum dots and their role in bioimaging of some pathogenic microorganisms
(Springer Science and Business Media B.V., 2023) Aakriti Prakash; Sujit Yadav; Punit Tiwari; Preeti S. Saxena; Anchal Srivastava; Ragini Tilak
Carbon quantum dots (CQDs) with outstanding fluorescence properties have shown enormous applications in bioimaging due to their biocompatibility and nano size attribute. However, the toxicity of QDs may hinder their implementation in biomedical use. Here, nitrogen-doped carbon quantum dots (N-CQDs) were produced by employing a microwave-assisted approach and then their in vivo and in vitro toxicity has been investigated. An in vitro toxicity study was conducted against human breast adenocarcinoma cell lines (MDA-MB-361) by considering the concentration of 0–600μg mL−1 of the N-CQDs and the in vivo toxicity examination was done in Swiss albino mice for 30 days by considering two concentrations of N-CQDs, i.e., 10mg/kg BW (body weight) and 20mg/kg BW. Several parameters have been inspected by these studies like cell viability, antioxidant enzymes studies, and hematological and histopathological studies, and concluded that the synthesized NCQDs are non-toxic and can be used safely for bioimaging. Furthermore, the luminescence properties of N-CQDs were inquired by labeling them on a variety of fungal and bacterial cells. When the N-CQD-labeled cells were excited at two wavelengths, it leads to the emission of green and red fluorescence enabling them ideal for bioimaging. Briefly, there is a production of inexpensive and biocompatible N-CQDs of an average particle size of ~3.16 nm that can serve as universal fluorescent agents for the detection of diverse groups of pathogenic microorganisms. © 2023, The Author(s), under exclusive licence to Springer Nature B.V.
Facile, rapid and upscaled synthesis of green luminescent functional graphene quantum dots for bioimaging
(Royal Society of Chemistry, 2014) Vinod Kumar; Vimal Singh; Sima Umrao; Vyom Parashar; Shiju Abraham; Anand K. Singh; Gopal Nath; Preeti S. Saxena; Anchal Srivastava
We report here the upscaled synthesis of green luminescent functionalized graphene quantum dots (FGQDs) by using an inexpensive and commonly occurring natural precursor viz. graphite powder. We observed in our sample that photoluminescence increases for excitation wavelengths of 300 nm to 350 nm and then decreases when excited at 375 to 425 nm for FGQDs at neutral pH. We found that the synthesized FGQDs do not show a drastic change in emission properties when kept under different pH conditions, which makes them a potential candidate for in vivo imaging, where the pH of the culture media plays a crucial role in the maintenance of the fluorescence. Water solubility, and excellent photostability along with low cytotoxicity of FGQDs are manifested as a remarkable bioimaging material. This journal is © the Partner Organisations 2014.
Functionalized WS2 Quantum Dots as Fluorescent Nanoprobes for In Vivo Bioimaging
(American Chemical Society, 2023) Suyash Rai; Vijay K. Singh; Brijesh Singh Chauhan; S. Srikrishna; Preeti S. Saxena; Anchal Srivastava
The strong fluorescence and high photostability of inorganic quantum dots (QDs) have envisaged them as superior fluorescent probes for biomedical imaging applications compared to organic dyes that are highly prone to photobleaching. However, earlier reports suggest that the potential use of inorganic QDs can be ensured only if they remain fluorescent and stably dispersed in water and other biological fluids under a wide pH range. In the present work, we address in detail the influence of pH (range 1.0-13.0) on the photophysical properties of functionalized tungsten disulfide QDs (f-WS2-QDs) synthesized using a facile, eco-friendly, and single-step hydrothermal approach. Experimental findings suggest that the fluorescence nature of as-produced f-WS2-QDs remains highly stable in harsh acidic to basic media. The PL stability and dispersion of f-WS2-QDs in aqueous media are explained in terms of various functional groups present over the QDs’ surface, which causes surface passivation of the QDs during hydrothermal growth leading to the high solubility and stable fluorescence of QDs in aqueous media. Furthermore, as a proof of concept, we have also demonstrated that the f-WS2-QDs could be potentially used as a fluorescent probe for high-contrast in vivo imaging of Drosophila third instar larvae. Thus, we anticipate that the present investigation may provide insight into the scientific community for the development of pH-universal inorganic QDs for biological applications. © 2023 American Chemical Society.
Graphene Oxide Synergistically Enhances Antibiotic Efficacy in Vancomycin-Resistant Staphylococcus aureus
(American Chemical Society, 2019) Vimal Singh; Vinod Kumar; Sunayana Kashyap; Ajay Vikram Singh; Vimal Kishore; Metin Sitti; Preeti S. Saxena; Anchal Srivastava
The current study highlights a new polyvalent inhibitor approach based on Vancomycin conjugated with graphene oxide (Van@GO) against a Vancomycin-resistant Staphylococcus aureus (VRSA) strain. Physicochemical characteristics of the prepared Van@GO composites were studied using UV-vis and FTIR spectroscopy techniques. Characterization results confirm the attachment of Vancomycin to the graphene oxide. A significant inhibition of VRSA growth is achieved by Vancomycin when presented as Van@GO. The polyvalent inhibition activity of Van@GO was characterized by performing bacteriological experiments along with scanning electron microscopy. Results clearly exhibit the enhanced inhibition activity of Van@GO compared to Vancomycin alone against VRSA. The high surface area of GO facilitates high loading and multivalent interaction of conjugated Vancomycin leading to polyvalent inhibition. Further, we found that Van@GO significantly reduces the motility of VRSA via inducing oxidative stress compared with untreated samples. Our findings highlight the importance of Van@GO as an effective polyvalent inhibition recipe for VRSA. © 2019 American Chemical Society.
High-performance and high-sensitivity applications of graphene transistors with self-assembled monolayers
(Elsevier Ltd, 2016) Chao-Hui Yeh; Vinod Kumar; David Ricardo Moyano; Shao-Hsuan Wen; Vyom Parashar; She-Hsin Hsiao; Anchal Srivastava; Preeti S. Saxena; Kun-Ping Huang; Chien-Chung Chang; Po-Wen Chiu
Charge impurities and polar molecules on the surface of dielectric substrates has long been a critical obstacle to using graphene for its niche applications that involve graphene's high mobility and high sensitivity nature. Self-assembled monolayers (SAMs) have been found to effectively reduce the impact of long-range scatterings induced by the external charges. Yet, demonstrations of scalable device applications using the SAMs technique remains missing due to the difficulties in the device fabrication arising from the strong surface tension of the modified dielectric environment. Here, we use patterned SAM arrays to build graphene electronic devices with transport channels confined on the modified areas. For high-mobility applications, both rigid and flexible radio-frequency graphene field-effect transistors (G-FETs) were demonstrated, with extrinsic cutoff frequency and maximum oscillation frequency enhanced by a factor of ~2 on SiO2/Si substrates. For high sensitivity applications, G-FETs were functionalized by monoclonal antibodies specific to cancer biomarker chondroitin sulfate proteoglycan 4, enabling its detection at a concentration of 0.01fM, five orders of magnitude lower than that detectable by a conventional colorimetric assay. These devices can be very useful in the early diagnosis and monitoring of a malignant disease. © 2015 Elsevier B.V.
In situ decorated 2D vanadium disulphide on optimized reduced graphene oxide-based interface for highly sensitive nonenzymatic glutamate detection
(Elsevier Ltd, 2024) Rim M. Alsharabi; Amit K. Patel; Jay Singh; Preeti S. Saxena; Anchal Srivastava
2D layered transition metal dichalcogenides (TMDs) possess eccentric nanostructures, large surface areas, and unique semiconducting properties, making them exceptional for non-enzymatic applications compared to metal oxides. However, TMDs like vanadium disulfide (VS2), with peroxidase-like nanozymatic characteristics, suffer from limited electronic conductivity, restricting their use as electrochemical (EC) sensors. To address this, reduced graphene oxide (rGO) is introduced to enhance electronic conductivity and leverage the enzyme-like property of VS2. This study introduces a novel enzyme-free EC sensor, rGO/VS2 nanocomposite-based, for accurate and efficient glutamate (Glut) detection. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) demonstrated that rGO/VS2 electrodes with varying rGO to VS2 composition ratios exhibit superior EC properties compared to pure VS2 electrodes. The EC response of the rGO/VS2 modified electrode towards Glut was investigated using CV and differential pulse voltammetry (DPV). The fabricated electrode displayed a linear relationship with Glut concentration (4–300 μM) (normal levels 30–80 μM), boasting a low limit of detection (LOD) (0.056 μM) and higher sensitivity (0.797 μA/(mM·cm2)) compared to existing non-enzymatic Glut sensors. Structural and morphological characterizations employed Raman spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and energy-dispersive X-ray spectroscopy (EDX). Furthermore, the proposed electrode's electroanalytical activity was assessed in spiked real samples, establishing its reliability and precision in Glut detection. The developed rGO/VS2-based EC sensor holds practical utility in biomedical research, clinical diagnostics, and environmental monitoring, where Glut detection is essential. © 2024 Elsevier B.V.
MWCNTs as reinforcing agent to the Hap-Gel nanocomposite for artificial bone grafting
(2010) Santosh K. Yadav; Tanmay Bera; Preeti S. Saxena; Ashok K. Maurya; Rajendra S. Garbyal; Robert Vajtai; P. Ramachandrarao; Anchal Srivastava
The essence of this investigation is to explore MWCNTs as reinforcing agents to strengthen Hap-Gel nanocomposites for artificial bone grafting applications without significantly compromising their biocompatibility. Hap-Gelatin composites, reinforced with various proportions of MWCNTs, were synthesized to optimize the MWCNT content in the composites which yield commendable improvement in the strength. The morphological studies reveal that the MWCNTs act as templates for nucleation of Hap crystals. The biocompatibility of MWCNT reinforced Hap-Gelatin composites were evaluated in animal model through the histopathological investigation of tissues from skin, kidney, and liver. On histopathological examination, no noticeable alteration due to toxicity was found for lower concentration of MWCNTs. Mild reversible changes in the liver and tubular damage in kidney have been observed for higher concentration (4 wt % of MWCNTs). It can be inferred from the findings that MWCNTs, in proportions less than 4%, can successfully be used to reinforce the Hap-Gel nanocomposite to improve its mechanical properties. However, how safe would these CNT reinforced bone implants would be when used for prolonged period in actual physiological conditions needs to be investigated further. © 2009 Wiley Periodicals, Inc.
Nanocomposites as bone implant material
(Springer Berlin Heidelberg, 2013) Vinod Kumar; Bipul Tripathi; Anchal Srivastava; Preeti S. Saxena
The increasing demand for a suitable bone implant material has been forcing researchers to work on various man-made materials that may be used as a suitable replacement for natural bone and are affordable and easy to fabricate. In the past years, although significant efforts have been made in tissue engineering and regenerative medicine to put forward an ideal bone implant, they are far from meeting the real objective. Recent advances in nanobiotechnology in the field of therapeutics hold great promise to achieve the objective of an ideal implant in proper synchronization with tissue engineering. Nanocomposites, a product of synergistic efforts in nanobiotechnology and tissue engineering towards an ideal orthopedic implant, possess enormous potential for use as suitable bone implant material. Along with discussing the existing/conventional bone implant materials and their shortcomings, the main focus of this chapter is to elucidate nanocomposite as a potential next generation bone implant material. In this review, attempts have been made to deliver concise and relevant information about various nanofabrication technologies, characterization of nanocomposites, and their in vitro and in vivo biocompatibility study. Primary investigations support that nanocomposites are an ideal implant material for orthopedic applications; however, substantial developments are still highly needed to put nanocomposites into real practice, where current leanings in nanobiotechnology foreshadow a bright future through the use of nanocomposites in orthopedics. After defining the quest for bone implants, Sect. 26.2 gives a brief introduction to bone, and its structure and composition will be discussed. Section 26.3 gives a description and highlights shortcomings of conventional implant materials, followed by Sect. 26.4 describing the challenges posed by conventional and existing implants. In Sect. 26.5 a detailed study of the possible role of nanotechnology for suitable orthopedic implants are presented. Future perspectives in Sect. 26.6 close the chapter. © Springer-Verlag Berlin Heidelberg 2013.