School Of Basic And Applied Sciences

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    Anisotropic short-range attractions precisely model branched erythrocyte aggregates
    (Royal Society of Chemistry, 2023-10-17T00:00:00) Yadav, Megha; Vanshika, None; Singh, Chamkor
    Homogeneous suspensions of red blood cells (RBCs or erythrocytes) in blood plasma are unstable in the absence of driving forces and form elongated stacks, called rouleaux. These erythrocyte aggregates are often branched porous networks - a feature that existing red blood cell aggregation models and simulations fail to predict exactly. Here we establish that alignment-dependent attractive forces in a system of dimers can precisely generate branched structures similar to RBC aggregates observed under a microscope. Our simulations consistently predict that the growth rate of typical mean rouleau size remains sub-linear - a hallmark from past studies - which we also confirm by deriving a reaction kernel taking into account appropriate collision cross-section, approach velocities, and an area-dependent sticking probability. The system exhibits unique features such as the existence of percolated and/or single giant cluster states, multiple coexisting mass-size scalings, and transition to a branched phase upon fine-tuning of model parameters. Upon decreasing the depletion thickness we find that the percolation threshold increases but the morphology of the structures opens up towards an increased degree of branching. Remarkably the system self-organizes to produce a universal power-law size distribution scaling irrespective of the model parameters. � 2023 The Royal Society of Chemistry.
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    Guided run-and-tumble active particles: wall accumulation and preferential deposition
    (Royal Society of Chemistry, 2021-09-20T00:00:00) Singh, Chamkor
    Bacterial biofilms cost an enormous amount of resources in the health, medical, and industrial sectors. To understand early biofilm formation, beginning from planktonic states of active suspensions (such asEscherichia coli) to micro-colonization, it is vital to study the mechanics of cell accumulation near surfaces and subsequent deposition. Variability in bacterial motion strategies and the presence of taxis fields make the problem even more multifaceted. In this study, analytical expressions for the density and angular distributions, mean orientation, and deposition rates in such bacterial suspensions are derived, with and without the effects of external guiding or taxis fields. The derived results are closely verified by simulations of confined active particles using run-and-tumble statistics from multiple past experiments and utilizing a preferential sticking probability model for deposition. The behavioral changes in cell running strategies are modeled by varying the run-time distribution from an exponential to a heavy-tailed one. It is found that the deposition rates can be altered significantly by a guiding torque but are less affected by a change in the cell running behavior. However, both the mechanisms alter the pair correlation function of the deposited structures. The factor behind the changes in the architecture of deposited biomass under a torque generating guiding field turns out to be an asymmetrical rotational drift of planktonic cells, which can be an important physical mechanism behind the organization in confined active particle suspensions. � The Royal Society of Chemistry 2021.
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    Energy Evolution, Stabilization, and Mechanotransducer Properties of Fe3 O4 Vortex Nanorings and Nanodisks
    (American Physical Society, 2021-08-02T00:00:00) Niraula, Gopal; Toneto, Denilson; Joshy, Elma; Coaquira, Jose A. H.; Ayesh, Ahmad I.; Garcia, Flavio; Muraca, Diego; Denardin, Juliano C.; Goya, Gerardo F.; Sharma, Surender K.
    Recent reports on spin structures produced in nanomaterials due to confinement of spins imposed by geometrical restrictions are at the center of rising scientific interest. Topological curling magnetic structures (vortices) exhibit unique properties, regarding the energy profile, good colloidal stability in suspensions, manipulation under a low-frequency magnetic field, and torque exertion. The last property provides the potential to mechanically eradicate cancer cells via magnetomechanical actuation using remote ac magnetic fields. Here, we study, theoretically and by micromagnetic simulations, the magnetic energy evolutions for vortex nanosystems, i.e., Fe3O4 nanodisks (NDs) and nanorings (NRs). The obtained results for magnetic energy, magnetic susceptibility, and magnetization reversal confirm that the vortex-domain structure in NRs exhibits better stability and avoids agglomeration in solution, owing to the presence of a central hole, whereas the presence of a vortex core in NDs induces magnetic remanence. Although NDs are found to exert slightly higher torques than NRs, this weakness can be compensated for by a small increase (i.e., approximately equals 20%) in the amplitude of the applied field. Our results provide evidence of the magnetic stability of the curling ground states in NRs and open the possibility of applying these systems to magnetomechanical actuation on single cells for therapeutics in biomedicine, such as cancer-cell destruction by low-frequency torque transduction. � 2021 American Physical Society.
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    Naphthylisoindolinone alkaloids: the first ring-contracted naphthylisoquinolines, from the tropical liana Ancistrocladus abbreviatus, with cytotoxic activity
    (Royal Society of Chemistry, 2022-10-12T00:00:00) Fayez, Shaimaa; Bruhn, Torsten; Feineis, Doris; Assi, Laurent Ak�; Kushwaha, Prem Prakash; Kumar, Shashank; Bringmann, Gerhard
    The West African liana Ancistrocladus abbreviatus is a rich source of structurally most diverse naphthylisoquinoline alkaloids. From its roots, a series of four novel representatives, named ancistrobrevolines A-D (14-17) have now been isolated, displaying an unprecedented heterocyclic ring system, where the usual isoquinoline entity is replaced by a ring-contracted isoindolinone part. Their constitutions were elucidated by 1D and 2D NMR and HR-ESI-MS. The absolute configurations at the chiral axis and at the stereogenic center were assigned by using experimental and computational electronic circular dichroism (ECD) investigations and a ruthenium-mediated oxidative degradation, respectively. For the biosynthetic origin of the isoindolinones from �normal� naphthyltetrahydroisoquinolines, a hypothetic pathway is presented. It involves oxidative decarboxylation steps leading to a ring contraction by a benzilic acid rearrangement. Ancistrobrevolines A (14) and B (15) were found to display moderate cytotoxic effects (up to 72%) against MCF-7 breast and A549 lung cancer cells and to reduce the formation of spheroids (mammospheres) in the breast cancer cell line. � 2022 The Royal Society of Chemistry.
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    Steering the antitumor drug discovery campaign towards structurally diverse indolines
    (Academic Press Inc., 2020) Thakur A.; Singh A.; Kaur N.; Ojha R.; Nepali K.
    Indoline framework is often perpended as a privileged heterocycle present in medicinally valuable compounds of natural and synthetic origin. This review article presents the rational approaches/strategies employed for the design of anticancer indolines along with the structure activity relationship and mechanistic insights revealed in the in-vitro and in-vivo assays. The chemist has always been fascinated towards the indoline ring for the construction of antitumor scaffolds owing to its versatility as evidenced by its existence in scaffolds inducing antiproliferative effects via diverse mechanisms. To the delight of medicinal chemist, the applicability of indoline has also been expanded towards the design of dual inhibitors (multitargeting anticancer agents) as well as PROTACS. Overall, it can be concluded that indoline moiety is a magic bullet and the scaffolds containing this ring are foraying towards detailed preclinical and clinical stage investigations by leaps and bounds.
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    Amino acid functionalized zinc oxide nanostructures for cytotoxicity effect and hemolytic behavior: Theoretical and experimental studies
    (Elsevier Ltd, 2017) Singh, Satvinder; Singh, Baljinder; Sharma, Prateek; Mittal, Anu; Kumar, Sanjeev; Saini, G.S.S.; Tripathi, S.K.; Singh, Gurinder; Kaura, Aman
    Blending of theoretical and experimental approach, provide an important strategy in designing the nanostructure at a microscopic level and helps in predicting the response of synthesized material towards inhibition of the growth of breast cancer cell. In this work, ab initio calculations using super cell approach are performed for three different amino acids (AAs)-Histidine (His), Arginine (Arg) and Aspartic acid (Asp) coated Zinc oxide (ZnO) nanostructures to explain the growth mechanism of nanoparticles (NPs) of different shapes. Based on the first principles calculations, we reveal that ZnO-AA (Arg and Asp) NPs results in rod like and ZnO-His NPs lead to tablet like configuration. Similar morphologies are fabricated using AAs through synthetic route. The effect of concentration ratio of reactants and pH has been studied. As synthesized samples, are characterized by using Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) and UV?Vis spectroscopy techniques. Based on the results, a plausible mechanism of formation of nanostructures has been proposed. The nanostructures with rod like morphology are found to be biocompatible with normal red blood cells and show cytotoxic effect as evaluated from hemolysis and cytotoxicity assays on breast (MCF-7, T47D, MDA-MB-231) & prostate cancer (PC-3) cell lines. ? 2017 Elsevier Ltd