Soumya Sundar Mati

Self-aggregation of MEGA-9 (N-nonanoyl-N-methyl-D-glucamine) in aqueous medium: physicochemistry of interfacial and solution behaviors with special reference to formation energetics and micelle microenvironment.

Self-aggregation of MEGA-9 (N-nonanoyl-N-methyl-D-glucamine), a nonionic sugar-based surfactant, was studied with respect to the effect of salt (NaCl) and ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) on its critical micelle concentration (cmc), aggregation number, hydrodynamic dimensions, energetics of micellization, and micellar microenvironment. Fluorimetry (both steady state and time resolved) was used to understand the microenvironments under the influence of additives. NaCl was found to decrease cmc, increase aggregation number (N), increase micellar size, and decrease enthalpy of micelle formation; the IL effect on the parameters was mostly opposite. The microscopic properties of micelles were probed using two fluorophores: one nonpolar C-153 (2,3,5,6-1H,4H-tetrahydro-8-trifluormethylquinolizino-(9,9a,1-gh)coumarin) and the other fairly polar ANS (8-anilinonaphthalene-1-sulfonate); they delivered information on the palisade layer and the peripheral region of the micelle interface, respectively. Energy of activation and entropy of activation of the dynamics of the probes were evaluated from their decay time, lifetime, and rotational movements in the regions of residency in the micelles. Density functional theory (DFT) calculations showed that the ternary combination MEGA-9/IL/H2O had the maximum interaction energy compared to any of the binary combinations. Thus, the ionic liquid reduced MEGA-9 self-association to a large extent.

Morphology control of nickel oxalate by soft chemistry and conversion to nickel oxide for application in photocatalysis

The present work provides an effective methodology for controlled room-temperature aqueous synthesis of nickel oxalate (NiOX) nanosheets and nanoflakes in the presence of anion rich self-assembled bilayers of catanionic surfactant comprising of anionic sodium dodecyl sulfate (SDS) and cationic cetyltrimethylammonium bromide (CTAB). Encouragingly alteration of the CTAB/SDS ratio played an extraordinary role to form nanoflakes and nanosheets of NiOX. Our synthetic approach is combined with calcination to produce antiferromagnetic spherical and hexagonal nickel oxide (NiO) nanoparticles (NPs) as the end product. Synthesized nanostructured NiOX and NiO were characterized by X-ray diffraction study (XRD), energy dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). TEM studies illustrated that spherical NiO NPs have an average size around 5–10 nm and that of hexagonal NiO NPs have average width of about 22–27 nm. Temperature and field dependent magnetic properties of spherical and hexagonal NiO nanomaterials (NMs) were measured by using a SQUID magnetometer which revealed canted antiferromagnetic and spin glass nature, respectively. In addition, we report photocatalytic activity of NiO NMs, investigated on the photodegradation of phenol under ambient conditions, and as expected, the NiO having largest surface area showed best catalytic efficiency. This biomimetic catanionic surfactant inspired approach which require only metal ions as reactants have a definite potential towards an alternative, simple way of synthesizing metal oxide NMs.

Probing the spectral response of a new class of bioactive pyrazoline derivative in homogeneous solvents and cyclodextrin nanocavities: a spectroscopic exploration appended by quantum chemical calculations and molecular docking analysis

Time-dependent density functional theory (TD-DFT) calculations and molecular docking analysis provide valuable insights, in addition to experimental evidence, on the newly synthesized pyrazoline derivative 5-(1′-(4-bromophenyl)-3a′,4′,5′,6′,6a′-hexahydrocyclopentapyrazoline)-3-methyl-1-phenyl-1H-pyrazole-4-carbonitrile (PZ) as a fluorescence recognition probe and its photophysical signature in homogeneous and heterogeneous cyclodextrin (CD) environments, in addition to its insertion mechanism inside CD. The spectral trends of PZ do not appear to originate only from changes to the solvent polarity, but also indicate hydrogen bonding interactions with a homogeneous medium. The encapsulation of PZ within supramolecular α-, β- and γ-CD hosts was investigated using fluorescence spectroscopic techniques. The results show the formation of both 1 : 1 and 1 : 2 PZ–CD inclusion complexes with β-CD and only a 1 : 1 complex with γ-CD. The measured lifetimes and steady state anisotropy values also show the same trend and reveal the mode of interaction of the probe with the CD moiety. Furthermore, molecular docking studies performed via molecular mechanics methods (MMC) indicate that the pyrazoline moiety of PZ is most likely oriented towards the dip inside the cyclodextrin cavity. Solvent-dependent spectral data using TD-DFT calculations on the optimized ground and excited state structures of PZ were found to correlate well with the experimental findings.

Aggregation-induced fabrication of fluorescent organic nanorings: selective biosensing of cysteine and application to molecular logic gate.

Self-aggregation behavior in aqueous medium of four naphthalimide derivatives has exhibited substitution-dependent, unusual, aggregation induced emission enhancement (AIEE) phenomena. Absorption, emission, and time-resolved study initially indicated the formation of J-type fluorescent organic nanoaggregates (FONs). Simultaneous applications of infrared spectroscopy, theoretical studies, and dynamic light scattering (DLS) measurements explored the underlying mechanism of such substitution-selective aggregation of a chloro-naphthalimide organic molecule. Furthermore, transmission electron microscopy (TEM) visually confirmed the formation of ring like FONs with average size of 7.5-9.5 nm. Additionally, naphthalimide FONs also exhibited selective and specific cysteine amino acid sensing property. The specific behavior of NPCl aggregation toward amino acids was also employed as a molecular logic gate in information technology (IT).

Controlled synthesis of spin glass nickel oxide nanoparticles and evaluation of their potential antimicrobial activity: A cost effective and eco friendly approach

Development of an easy sustainable synthetic pathway towards oxide nanomaterials (NMs) is a necessary challenge for nanotechnology research workers. Additionally, antimicrobial activity of oxide nanoparticles against multi drug resistance pathogenic bacteria motivates scientists to focus their research on oxide materials. We report here a cost effective, simple and eco-friendly pathway of synthesizing NiO nanoparticles (NPs). X-ray diffraction and energy dispersive X-ray study confirmed their crystallinity and composition. Field emission scanning electron microscope (FESEM) was employed to understand their surface architecture and the dimension of synthesized NiO NPs were found to be 20–30 nm from transmission electron microscope (TEM) study. The as synthesized NiO demonstrated typical spin glass behaviour which is one advantage of our synthetic procedure. Antimicrobial properties of NiO NPs were investigated using Gram negative and Gram positive bacteria and their bactericidal effects were determined from minimum inhibitory concentrations (MIC) and Minimum bactericidal concentrations (MBC). Haemolytic activity revealed the nontoxic nature of the NPs towards the blood proteins at MBC. TEM images of bacteria cells treated with NiO NPs showed irreversible damages to the cell wall leading to cell death. In light of our findings a possible mechanism of the antimicrobial effect of NiO NPs has been proposed.

Differential contribution of Igepal and CnTAB micelles on the photophysics of nonsteroidal drug Naproxen

Spectroscopic studies of Naproxen (NP), a nonsteroidal drug have been carried out in well characterized, micellar media of cationic surfactants of a homologous series having general formula C(n)TAB (alkyl trimethyl ammonium bromide) and of nonionic surfactants of Igepal (Ig) series (poly(oxyethylene) nonyl phenol). The fluorescence behavior of the drug molecule in C(n)TAB micelles has been found to be opposite to that in Igepal micelles. The binding constants during probe micelle binding have been evaluated from relevant fluorescence data. Location and nature of the surrounding medium of the probe in micellar media have been ascertained from fluorescence quenching study. Fluorescence anisotropy parameter has been monitored for exploring the imposed motional restriction of the microenvironment around the probe. Contrasting behavior of the drug molecule has been observed in two different types of micelles. Based on the experimental and theoretical studies, an attempt has been made to explain the different behavior of the probe in different media.

Micellar charge induced emissive response of a bio-active 3-pyrazolyl-2-pyrazoline derivative: a spectroscopic and quantum chemical analysis

The medium charge specific excited state behaviour of a bio-active and fluorescent 3-pyrazolyl-2-pyrazoline derivative (PYZ) was systematically monitored in aqueous solutions of ionic (CTAB, SDS) and non-ionic (Triton X-100) micelles, applying steady state and time resolved fluorescence spectroscopy in addition to theoretical molecular simulations. PYZ displays complementary emission characteristics according to the nature of the effective charge of the micelles which was rationalized on the very fundamental basis of the frontier molecular orbital approach as obtained from quantum chemical calculations involving Time Dependent Density Functional Theory (TD-DFT) in combination with B3LYP exchange correlation function using 6-31G(d,p) as the basis set. Dynamic Light Scattering (DLS) measurements provided crucial information regarding the fluorescence quenching pattern of micelle bound PYZ by quencher CpCl. This study essentially accentuates PYZs photophysical response in different micellar media in conjunction with their individual mode of electrostatic interaction therein. The theoretically calculated HOMO–LUMO energy gap values provide adequate information about the emissive behaviour of PYZ in ionic micellar media. The variation in the lifetime values of PYZ in aqueous and micellar media act as added evidence of the fact that PYZ basically resides in different micro-environments as introduced by the respective micelles. Conclusively it was observed that, in the excited state, PYZ responded promptly and uniquely according to the nature of the micellar charge.

Toxicological assessment of PEG functionalized f-block rare earth phosphate nanorods

The emerging development of rare earth nanotechnology in daily science has aroused serious concerns regarding its impact on health care systems. Despite the potential uses of rare earth (RE) nanoparticles for targeted drug delivery, detection/diagnosis and imaging, potential nanoparticle toxicity must be investigated before any in vivo medicinal applications can move forward. In this account, we illustrate the toxicological assessment of polyethylene glycol (PEG) functionalised Ln3+ (Ce3+, Tb3+) doped rare earth phosphate (LaPO4) nanorods. The first part of the work describes the synthesis of the nanorods employing a biologically compatible reaction environment using a H2O–EtOH solvent mixture, reflux temperature and a ligand exchange methodology. Thereafter, the synthesized materials have been purified and characterized. The later part of the work discusses the in vivo toxicity of the nanomaterial. Synthesized nanorods were suspended in a buffer and administered to mice through intraperitoneal (IP) injection over a period of 7 days (high dose 125 mg kg−1) and 28 days (high dose 125 mg kg−1 and low dose 12.5 mg kg−1). Analysis of the serum biochemistry and haematology followed by histopathology indicates inflammation in the liver. The biodistributions of rare earth ions (La3+, Ce3+ and Tb3+) were analyzed using inductively coupled plasma mass spectrometry (ICPMS). Additionally, cellular viability of the synthesized nanorods was also studied using spleen mononuclear cells of Swiss albino mice.

Spectroscopic and Quantum Mechanical Approach of Solvatochromic Immobilization: Modulation of Electronic Structure and Excited-State Properties of 1,8-Naphthalimide Derivative

AbstractPhotophysical and spectroscopic properties of a fluorescent analogue, 2-(5-selenocyanato-pentyl)-6-chlorobenzo- [de]isoquinoline-1,3-dione (NP) in different solvents has been described in this paper using steady-state, time resolved spectroscopy and density functional theory (DFT) calculation. Stoke’s shifted emission band in different solvents clearly demonstrate the highly polar character of the excited state, which is also supported by the enhancement of dipole moment of the molecule upon photoexcitation. Spectroscopic studies and multiple linear regression analysis method reveal that the solvatochromic behavior of the probe depends not only on the polarity of the medium but also on the hydrogen bonding interaction with the solvents. When the solvent effect was taken into account, the computed results show encouraging agreement with known experimental data. This article reveals the excellent correlation between the predicted and experimental spectral data of 1,8-naphthalimide derivative, providing a useful tool in the design of new fluorogenic probes having potential therapeutic activity. Graphical AbstractSolvent dependent spectroscopic measurements of 1,8 Naphthalimide in corroboration with quantum chemical calculation.

CB7 as a drug vehicle and controlled release of drug through non ionic surfactant: Spectroscopic technique

A study of the comparative drug carrier properties of cucurbituril[7] (CB7) and β-cyclodextrin (β-CD) with a naphthalimide derivative, [2-(2-aminoethyl)-1H-benzo[deisoquinoline-1,3(2H)-dione] (NAP) and its release in aqueous solution using micellar environment, is the key research interest of this work. The profound changes in the different spectroscopic behavior have been attributed to the formation of a 1:1 inclusion complex for NAP:CB7 system. Several experimental outcomes clearly interpreted that CB7 has better drug carrier properties for NAP compared to β-CD. It has been also focused on the systematic release of NAP molecule from CB7 by using different ionic and non ionic surfactants. Before releasing the drug molecules from CB7 the interaction between NAP and the three different types of surfactants has also been investigated separately. The selectivity of drug carrier and releaser has been monitored, using different spectroscopic techniques like absorbance, fluorescence, fluorescence decay life time and 1H NMR spectroscopy. Besides, a theoretical approach has been followed for a proper geometrical optimized structure of NAP molecule and molecular arrangement of NAP:CB7 inclusion complex. From Density Functional Theory (DFT) it has been seen that NAP molecule is oriented as a t-bone like structure in its optimized form.