Publications by authors named "Sakthivel N"

Machining process involves numerous variables that can influence the desired outcomes, with surface roughness being a critical quality index for machined products. Surface roughness is often a technical requirement for mechanical products as it can lead to chatter and impact the functional performance of parts, especially those in contact with other materials. Therefore, predicting surface roughness is essential.

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The prevalence of cancer is increasing steadily over the past few decades due to social and environmental factors. Several drugs and medications have also been reported, but with inevitable side effects. Herein comes the urgent need for the development of precision medicine, which increases the efficiency of the drug on the target tissue and minimizes systemic toxicity and non-specificity.

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Green synthesis of nanoparticles provides numerous advantages over physical and chemical methods because of low toxicity, high yields, cost-effectiveness, environmentally benign, and energy efficiency. Therefore, we focused on the facile and green synthesis of isotropic silver nanoparticles using the metabolic extract of Cytobacillus kochii. During synthesis, the physicochemical parameters were optimized and validated using the response surface methodology statistical tool.

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The one-pot self-assembly of Mn(CO), a bis-chelated diaminobenzoquinonato (ON∩ON) bridge (L), and a linear ditopic linker (N∩N) (L') has resulted into the formation of MLL'-type manganese(I)-based tetranuclear metallorectangles of the general formula [{(CO)Mn(μ-η-L)Mn(CO)}(μ-(N-N))] (-), wherein L is 2,5-bis(-butylamine)-1,4-benzoquinone () and/or 2,5-bis(phenethylamino)-1,4-benzoquinone () and N-N is 4,4'-bipyridine (), -1,2-bis(4-pyridyl) ethylene (), phenyl-1,4-bis(isonicotinate) (), and ,'-bis(4-pyridylformamide)-1,4-benzene (). Metallorectangles - were characterized by infrared, ultraviolet-visible (UV-vis) absorption, and H nuclear magnetic resonance spectroscopies, elemental analysis, and electrospray ionization-mass spectrometry. The molecular and crystal structures of •(CHCl) and coronene⊂•coronene were determined by the single-crystal X-ray diffraction method.

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Supramolecular one-step self-assembly of dimanganese decacarbonyl, diaryl diselenide, and linear dipyridyl ligands (L = pyrazine (pz), 4,4'-bipyridine (bpy), and -1,2-bis(4-pyridyl)ethylene (bpe)) has resulted in the formation of selenolato-bridged manganese(I)-based metallorectangles. The synthesis of tetranuclear Mn(I)-based metallorectangles [{(CO)Mn(μ-SeR)Mn(CO)}(μ-L)] (-) was facilitated by the oxidative addition of diaryl diselenide to dimanganese decacarbonyl with the simultaneous coordination of linear bidentate pyridyl linker in an orthogonal fashion. Formation of metallorectangles - was ascertained using IR, UV-vis, NMR spectroscopic techniques, and elemental analyses.

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Highly monodisperse and pure samples of atomically precise gold nanomolecules (AuNMs) are essential to understand their properties and to develop applications using them. Unfortunately, the synthetic protocols that yield a single-sized nanomolecule in a single-step reaction are unavailable. Instead, we observe a polydisperse product with a mixture of core sizes.

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Article Synopsis
  • - The research discusses the discovery of a unique Janus nanomolecule, Au(SPh-Bu), which exhibits both molecular and metallic features, linking smaller nanoparticle structures to bulk-like properties in metals.
  • - The Au core of the nanomolecule has a complex structure with an 89-atom inner core and a shell of ligands, showcasing a transitional evolution from twinned to untwinned configurations as particle size increases.
  • - The study highlights how the optical and electronic properties of the Janus nanoparticle, including its ability to stabilize electronic structures, contribute to its unique characteristics and overall stability, bridging the gap between molecular and bulk metal behaviors.
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We report the X-ray crystal structure of the AuAg(S-Bu) alloy and the effect of the ligand on alloying site preferences. Gold-silver nanoalloys prepared by co-reduction of metal salts are known to have only partial Ag occupancies. Interestingly, AuAg(S-Bu) has on the surface, capping, and staples sites.

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In the present study, the interaction between the HSA and MnCORM in vitro under physiological conditions, was investigated through ultraviolet-visible (UV-vis) absorption, fluorescence, time-resolved fluorescence, circular dichroism (CD), Fourier transform infrared (FT-IR) spectroscopic techniques and in silico molecular docking methods. Binding parameters such as the binding constant, number of binding sites and binding force were obtained from the fluorescence data. Thermodynamic interaction revealed that the reaction was spontaneous (ΔG < 0) and hydrogen bond and van der Waals interaction were primarily involved in the binding.

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Multicomponent self-assembly of Mn(CO), a bis-chelating aminoquinonato (ON∩ON) bridge (L), and an ester/amide-functionalized flexible neutral ditopic linker (L') has resulted into the formation of MLL'-type manganese(I)-based dinuclear metallastirrups of general formula [{(CO)Mn(μ-η-L)Mn(CO)}(μ-L')] (-). Compounds - were accomplished via orthogonal bonding of the aminoquinone ligand (2,5-bis(-butylamino)-1,4-benzoquinone/2,5-bis(phenethylamino)-1,4-benzoquinone) and ditopic pyridyl ligand to manganese carbonyl. The resultant metallastirrups were characterized using elemental analyses and IR, UV-vis, H NMR, and electrospray ionization-mass spectroscopic techniques.

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Silver nanoparticles loaded fibrillar collagen-chitosan matrix (CC) was prepared by biomimetic approach by blending silver nanoparticles (tAgNPs), collagen fibril and chitosan hydrogel followed by cross-linking and biomineralization. Electron micrograph showed that the surface of the composites exhibited native fibrillar morphology of collagen and their cross-section revealed layer-like arrangement of native fibrillar collagen. The mineralized composites exhibited surface mineralization of calcium phosphates incorporated with magnesium.

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Carbon monoxide releasing molecules (CORMs) are organometallic/organic compounds that release carbon monoxide (CO) spontaneously or upon activation. PhotoCORMs are capable of releasing CO on light based activation. This group of molecules is used in photodynamic therapy due to their ability to release CO in a controlled manner.

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The nature of the ligands dictates the composition, molecular formulae, atomic structure and the physical properties of thiolate protected gold nanomolecules, Au(SR). In this review, we describe the ligand effect for three classes of thiols namely, aliphatic, AL or aliphatic-like, aromatic, AR, or bulky, BU thiol ligands. The ligand effect is demonstrated using three experimental setups namely: (1) The nanomolecule series obtained by direct synthesis using AL, AR, and BU ligands; (2) Molecular conversion and interconversion between Au(S-AL), Au(S-AR), and Au(S-BU) nanomolecules; and (3) Synthesis of Au, Au, and Au nanomolecules from one precursor Au(S-glutathione) upon reacting with AL, AR, and BU ligands.

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Thiolate-protected gold nanoparticles (AuNPs) are a special class of nanomaterials that form atomically precise NPs with distinct numbers of Au atoms ( n) and thiolate (-SR, R = hydrocarbon tail) ligands ( m) with molecular formula [Au (SR) ]. These are generally termed Au nanomolecules (AuNMs), nanoclusters, and nanocrystals. AuNMs offer atomic precision in size, which is desired to underpin the rules governing the nanoscale regime and factors affecting the unique properties conferred by quantum confinement.

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We report a detailed study on the optical properties of Au(SR) using steady-state and transient absorption measurements to probe its metallic nature, time-dependent density functional theory (TDDFT) studies to correlate the optical spectra, and density of states (DOS) to reveal the factors governing the origin of the collective surface plasmon resonance (SPR) oscillation. Au is the smallest identified gold nanocrystal to exhibit SPR. Its optical absorption exhibits SPR at 510 nm.

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We report the discovery of an unprecedentedly large, 2.2 nm diameter, thiolate protected gold nanocrystal characterized by single crystal X-ray crystallography (sc-XRD), Au(SPh-tBu) named Faradaurate-279 (F-279) in honor of Michael Faraday's (1857) pioneering work on nanoparticles. F-279 nanocrystal has a core-shell structure containing a truncated octahedral core with bulk face-centered cubic-like arrangement, yet a nanomolecule with a precise number of metal atoms and thiolate ligands.

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A novel guaiane sesquiterpene derivative, guai-2-en-10α-ol, from Ulva fasciata Delile exhibits antimicrobial property. U. fasciata extract was reported to exhibit cytotoxicity against cancer.

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Production of AgNPs with desired morphologies and surface characteristics using facile, economic and non-laborious processes is highly imperative. Cell extract based syntheses are emerging as a novel technique for the production of diverse forms of NPs, and is assured to meet the requirements. Therefore, in order to have a better understanding, and to improvise and gain control over the NPs morphological and surface characteristics, the present investigation systematically evaluates the influence of various major physico-cultural parameters including diverse growth media, concentrations of precursor salts; pH and temperature on the biotransformation of ionic silver (Ag) to nanopariculate silver nanoparticles (AgNPs), utilizing the cell free extract of the bacterium, P.

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Novel Cellulose (Cel) reinforced polyvinyl alcohol (PVA)-Silica (Si) composite which has good stability and in vitro degradation was prepared by lyophilization technique and implanted using N(3+) ions of energy 24keV in the fluences of 1×10(15), 5×10(15) and 1×10(16)ions/cm(2). SEM analysis revealed the formation of microstructures, and improved the surface roughness on ion implantation. In addition to these structural changes, the implantation significantly modified the luminescent, thermal and mechanical properties of the samples.

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A series of heteroleptic mononuclear copper(II) complexes of the type [Cu(L(1-3))(diimine)]ClO4 (1-6) containing three tetrazolo[1,5-a]pyrimidine core ligands, ethyl 5-methyl-7-(2-hydroxyphenyl)-4,7-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylate (HL(1)), ethyl 5-methyl-7-(4-diethylamino-2-hydroxyphenyl)-4,7-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylate (HL(2)) or ethyl 5-methyl-7-(2-hydroxy-4-nitrophenyl)-4,7-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylate (HL(3)), and two diimine coligands, 2,2'-bipyridyl (bpy) or 1,10-phenanthroline (phen) have been synthesized and characterized by spectral methods. The geometry of complexes have been determined with the help of electronic absorption and EPR splitting patterns, which suggest four coordinated square planar geometry around copper(II) ion. The lowering of HOMO-LUMO band gap value of complex 4 implies its higher biological activity compared to other complexes.

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Marine bacterium, strain MB30 isolated from the deep sea sediment of Bay of Bengal, India, exhibited antimicrobial activity against human pathogenic bacteria. Based on the 16S rRNA sequence homology and subsequent phylogenetic tree analysis, the strain MB30 was identified as Staphylococcus sp. The bioactive metabolite produced by the strain MB30 was purified through silica gel column chromatography and preparative HPLC.

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The microbial polyketide, 2, 4-diacetylphloroglucinol (DAPG), exhibited a broad-spectrum of anti-leukemic, anti-lung, and anti-breast cancer properties. The aim of the present investigation was to study the interactive potentials of DAPG with the metastatic proteins such as MMP-2, MMP-9, and NF-κB and antiapoptotic Bcl-2 family proteins such as Bcl-2, Bcl-w, and Bcl-xL through in silico interaction and in vitro studies. The in silico modeling predicted high interactions of DAPG with the metastatic proteins, especially MMP-2, MMP-9, and NF-κB with the glide score of -7.

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A new set of ester functionalised Re(i)-based oxamidato bridged neutral dinuclear metallacycles were synthesised by self-assembly of four components from three building blocks in a facile one-pot reaction via an orthogonal bonding approach. Oxidative addition of oxamide ligands (H2L = N,N'-diphenyloxamide, and N,N'-dibenzyloxamide) to rhenium carbonyl (Re2(CO)10) in the presence of semi-rigid and flexible ditopic pyridyl ligands (L' = o-phenylene diisonicotinate (pdi), ethane diyl di-4-pyridine carboxylate (etdp) and 1,4-butane diyl di-4-pyridine carboxylate (budp)) having ester functionality afforded neutral dirhenium metallacycles of the general formula [(CO)3Re(μ-L)(μ-L')Re(CO)3] (1-5) under solvothermal reaction conditions. The metallacyclic compounds were characterised using elemental analyses, IR, UV-vis and NMR spectroscopic techniques.

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The 2,4-diacetylphloroglucinol (DAPG), a polyketide metabolite extracted from Pseudomonas aeruginosa strain FP10, exhibited selective cytoxicity against lung (A549), breast (MDA MB-231), cervical (HeLa) and colon (HCT-15) cancer cells in differential and dose-dependent manner. The anticancer and antimetastatic activities of DAPG were mediated by the inhibition of ROS, NF-κB, Bcl-2, MMP-2, VEGF and primary inflammatory mediators such as TNF-α, IL-6, IL-1β and NO. The DAPG induced apoptosis in cancer cells by intrinsic and extrinsic pathways via the release of cytochrome-C, upregulation of Bax and the activation of caspases and also, exhibited anti-inflammatory activity by the inhibition of LPS-inflammed cell proliferation of macrophage (Raw 264.

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