BITS Faculty Publications

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    Revealing the role of electrostatics in gold-nanoparticle-catalyzed reduction of charged substrates
    (ACS, 2017-09) Rao, Anish
    The potency of electrostatic effects arising from nanoparticle (NP) surface in Au-NP-catalyzed reduction of charged substrates are presented. The electrostatic potential around Au NPs is controlled by varying the nature of ligands and ionic strength of the medium. Favorable interactions arising from the attraction between oppositely charged Au NP and substrates results in the channeling of substrates to the NP surface, which in turn enhances the catalytic reduction. The positively charged ([+]) Au NP outperformed other NP systems despite having comparable or even lower surface area for adsorption, proving the exclusivity of electrostatics in catalysis. At least an order of magnitude higher concentration of negatively charged ([−]) Au NP is required to compete with the catalytic activity of [+] Au NP.
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    Emergence of selectivity in inherently nonselective gold nanoparticles through preferential breaking of interparticle interactions
    (2018-10) Rao, Anish
    We demonstrate a fundamentally unique identification strategy to impart selectivity to a traditionally and inherently nonselective carboxylate-functionalized gold-nanoparticles ([-] AuNPs), without the aid of any analyte specific ligands. The common practice is to use the ability of divalent ions to trigger the aggregation process in a kinetically trapped dispersed solution of [-] AuNPs. Aggregation of NPs being a thermodynamically favourable process will result in a uniform and nonselective turn-off response from most of the strongly binding divalent ions. Our approach is to use the abilities of various divalent ions to break a thermodynamically stable inter-nanoparticle precipitates containing [+] and [-] AuNPs (nanoionic precipitates), as the means of identification. Importantly both [+] and [-] AuNPs, independently, were ‘blind’ in terms of selectivity towards divalent ions. Remarkably, a hybrid-system composed of such nonselective nanoparticles was able to discriminate between the hard-to-distinguish pair of Pb2+ and Cd2+ ions. The rationale is that only the strongest of strongly binding ions will be able to break the interactions between the NP precipitates (thermodynamically stable state) and re-disperse them back in solution (kinetically trapped state). This is in stark contrast with the conventional idea of forming an interaction between NPs and divalent ions, with the help of analyte-specific ligands.
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    Mechanisms of action of nanoparticles in living systems
    (IGI Global, 2021) Yadukrishnan, Premachandran
    Nanoparticles are being formed continuously in processes like mineralization, natural calamities, and geological recycling of matter and present naturally in the environment. In the recent past, nanoparticles and their applications have become an extensive topic of research. Application of nanomaterials in different industries will surely enhance the chances of discharge of nanoparticles into the environment. So, a number of studies have been performed to explore the mode of action of nanoparticles on living organisms and their surroundings. The most reported modes of action of nanoparticles are antimicrobial activity, ROS-induced cytotoxicity, genotoxicity, plant growth promotion, etc. It has been successfully demonstrated that actions of nanoparticles are governed by their size, shape, dose, and concentration. However, a complete mechanism of action of nanoparticles has not been known. The present chapter focuses on the highlights of the mechanisms behind the mode of action of nanoparticles in plants and microorganisms.
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    Fabrication of Au decorated MoS2 Langmuir Blodgett film as SERS sensing scaffold for detection of thiram in aqueous solution and in carrot peels
    (Elsevier, 2024-10) Pande, Surojit
    This paper is focused on simple fabrication of robust and reproducible SERS active substrate through self-assembly of gold nanoparticles (AuNps) entrapped in the Langmuir Blodgett (LB) film of MoS2 flakes. The as prepared Au-MoS2 substrate can detect SERS signals of 4-Mercapto Pyridine (4-Mpy) molecules at trace concentrations down to 10-12 M. The substrate has been further employed in detecting thiram (TH) both in aqueous solution and in carrot peels (CPls). The limit of detection (LOD) of TH in aqueous medium and in CPls have been estimated to be ∼ 5.18 and 10.16 pM respectively. We believe that the applicability of this SERS active substrate may be extended in the trace detections of explosives, drugs and in diagnostic applications.
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    Impact of protein nanoparticles on beer foam
    (Springer, 2023-06) Roy, Banasri; Chattopadhyay, Pradipta
    Beer foam adds a visual aesthetic to the beer- a good beer foam layer presents the beer as fresh and tasty and attracts customers. Beer foam also helps in maintaining the flavor of the beer by acting as an airtight blanket preventing the escape of CO2 from the beer. Thus, stable, long-lasting beer foam is preferred in the final product irrespective of consumer preferences. Beer foam stability is impacted by the proteins and protein nanoparticles. This work encompasses the effects that proteins and protein nanoparticles have on foaming in beer. Studies regarding the impact of protein nanoparticles on the quality of beer foam are also discussed.
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    Melting of dsDNA attached with AuNPs
    (Springer, 2023-07) Singh, Navin
    DNA-linked gold nanoparticles (DNA-AuNPs) are combined nanomaterials that contain the optical and electronic properties of AuNPs with the unique functions of DNA. These hybrid systems are used in various nanobiotechnology, medical, and pharmaceutical sciences (Löwe et al. in FEBS J 287(23):5039, 2020; Speer et al. in Annu Rev Biophys 51:267, 2022). In recent years, there has been an increasing interest in studying the behavior of DNA-AuNPs in the presence of molecular solvents. In the present work, we study the thermal melting of DNA-linked gold nanoparticles (DNA-AuNP). In the first part of the study, we find the melting profile of short heterogeneous DNA-linked AuNP in the presence of solvent in the solution. We also study the effect of the location of the gold nanoparticle attached to the DNA molecule. In this case, we move the location of the AuNP from one end to the other. We found that while the melting temperature is susceptible to the location of the AuNP when it is near the ends, there is a region in the middle section of the chain where the melting temperature remains constant.
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    Plant polysaccharides-based nanoparticles for drug delivery
    (Elsevier, 2023) Jain, Ankit
    Recently natural polysaccharides have gained attention for the design of nanoparticles (NPs) for the effective delivery of drugs. These polysaccharides have several advantages such as biodegradability, biocompatibility, and low cytotoxicity. Several studies have reported nanoparticle-based drug delivery systems showing effective localization of drugs into the target site. It provides a combined effect toward the development of biodegradable/biocompatible NPs with high potential of passive/active targeting and reduced undesirable side effects of the drug. Additionally, the size of NPs plays a key role in the use of these structures as drug/gene carriers as well as trans-membrane transporters. The plant polysaccharides also provide a large number of reactive groups, and specific targeting can be achieved by surface modification of NPs with targeting ligands. Moreover, the mucoadhesive properties of these polysaccharides could be used to prolong the retention time of drug delivery at the site of absorption. This chapter deals with the classification of polysaccharides, their advantages and disadvantages. It includes polysaccharides such as pectin, guar gum, alginate, gum tragacanth, gum acacia, locust bean gum, cellulose, starch, gum karaya, and cashew gum. This chapter also discusses the application of polysaccharides-based NPs in the treatment of cancer.
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    Nano-formulated siRNA-based therapeutic approaches for cancer therapy
    (Elsevier, 2023-03) Jain, Ankit
    RNAi is a remarkable treatment strategy to knock down gene overexpression in a variety of disorders, including cancers. RNAi processes allow siRNAs to detect and degrade a homologous mRNA sequence in the cell. However, the limited potential of siRNA delivery to target cells, poor cellular uptake, off-target effect, and their breakdown by serum nucleases in systemic circulation are limiting factors for their therapeutic applications. Over the past few years, siRNA drugs are undergoing a period of clinical translation. Therefore, this review mainly highlights the state-of-the-art of nanocarriers for delivering siRNA cargos and their coadministration with anticancer drugs, along with their applications in cancer treatment. Besides, molecular manifestations, challenges in the delivery of siRNA, design, and development of siRNA-based delivery systems, merits, and demerits of different nanocarriers have been discussed. The endosomal trapping of siRNA is a major difficulty for most delivery strategies, influencing the therapeutic effect. To address this issue various approaches for siRNA release including pH-responsive release, membrane fusion, proton sponge effect, and photochemical disruption have been discussed. Finally, the current status of siRNA therapeutics in clinical trials is explored, providing a systematic and comprehensive overview of siRNA-based therapeutics for effective cancer treatment.
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    Entropy generation optimization for the electroosmotic MHD fluid flow over the curved stenosis artery in the presence of thrombosis
    (Springer Nature, 2023-09) Sharma, Bhupendra Kumar
    The present study deals with the entropy generation analysis on the flow of an electrically conductive fluid (Blood) with -suspended nanoparticles through the irregular stenosed artery with thrombosis on the catheter. The fluid flow can be actuated by the interactions of different physical phenomena like electroosmosis, radiation, Joule heating and a uniform radial magnetic field. The analysis of different shapes and sizes of the nanoparticle is considered by taking the Crocine model. The velocity, temperature, and concentration distributions are computed using the Crank–Nicholson method within the framework of the Debye–Huckel linearization approximation. In order to see how blood flow changes in response to different parameters, the velocity contour is calculated. The aluminium oxide nanoparticles employed in this research have several potential uses in biomedicine and biosensing. The surface’s stability, biocompatibility, and reactivity may be enhanced by surface engineering, making the material effective for deoxyribonucleic acid sensing. It may be deduced that the velocity profile reduces as the nanoparticle’s size grows while depicts the reverse trend for the shape size. In a region close to the walls, the entropy profile decreases, while in the region in the middle, it rises as the magnetic field parameter rises. The present endeavour can be beneficial in biomedical sciences in designing better biomedical devices and gaining insight into the hemodynamic flow for treatment modalities.
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    Electromagnetohydrodynamics Casson pulsatile nanofluid flow through a bifurcated stenosed artery: Magnetically targeted drug delivery
    (AIP, 2023-11) Sharma, Bhupendra Kumar
    The current study is centered on the application of magnetically targeted drug delivery in a constricted vertical bifurcated artery utilizing Fe O nanoparticles. The arterial stenosis is characterized by a bell-shaped narrowing in the parent artery and overlapping narrowing in the daughter artery. The blood is regarded as exhibiting the rheological behavior of a Casson fluid. The temperature-dependent nature of blood viscosity is postulated, and Reynold’s viscosity model describes it. This study examines the impact of electromagnetohydrodynamics (EMHD), body acceleration, Joule heating, and viscous dissipation. The assumption of a no-slip velocity condition is made at the walls of the artery. The governing equations are subjected to a process of non-dimensionalization and simplification, employing the mild-stenosis approximation. The resulting equations are subsequently solved in MATLAB by employing the finite-difference Crank–Nicolson technique. Entropy plays a significant role during any treatment or surgery; therefore, the present problem addresses entropy generation minimization. The results for velocity, temperature, wall shear stress, flow rate, impedance, heat transfer rate, entropy generation number, and Bejan number are represented graphically. The velocity contours illustrate that the flow velocity enhances with the Casson fluid and particle mass parameters. Furthermore, the number of trapped bolus also increases in the daughter artery. The nanofluid velocity and particle velocity decrease with an increase in the particle concentration parameter in the parent artery and the daughter artery. Entropy declines with the temperature difference parameter increment, whereas the Bejan number enhances. Magnetite (Fe O ⁠) nanoparticles have various applications owing to their biocompatibility, elevated magnetic susceptibility, chemical stability, non-toxic nature, and cost-effectiveness.