Synthesis and Characterization of Cobalt(III) and Copper(II) Complexes of 2-((E)-(6-Fluorobenzo[d]thiazol-2-ylimino) methyl)-4-chlorophenol: DNA Binding and Nuclease Studies—SOD and Antimicrobial Activities

A bidentate (N- and O-) imine-based ligand (L1) and its metal complexes of types [CuII(L1)2] (C1), [CuII(L1)(Phen)] (C2), [CoIII(L1)2] (C3), and [CoIII(L1)(Phen)] (C4) (L1 = 2-((E)-(6-fluorobenzo[d]thiazol-2-ylimino)methyl)-4-chlorophenol and phen = 1,10-phenanthroline) were synthesized as potential chemotherapeutic drug candidates. The prepared complexes were structurally characterized by spectral techniques (NMR, FT-IR, LC-MS, EPR, and electronic absorption), thermogravimetric analysis (TGA/DTA), magnetic moment, and CHNO elemental analysis. Spectroscopic studies suggested the distorted octahedral structure for all complexes. In vitro bioassay studies include binding and nuclease activities of the ligand and its complexes with target calf thymus- (CT-) DNA were carried out by employing UV-Vis, fluorescence spectroscopy, viscosity, and gel electrophoresis techniques. The extent of binding propensity was determined quantitatively by Kb and Ksv values which revealed a higher binding affinity for C2 and C4 as compared to C1 and C3. In addition, the scavenging superoxide anion free radical (O∙-2) activity of metal complexes was determined by nitroblue tetrazolium (NBT) light reduction assay. Molecular docking studies with DNA and SOD enzyme were also carried out on these compounds. The antimicrobial study has shown that all the compounds are potential antibacterial agents against Gram-negative bacterial strains and better antifungal agents with respect to standard drugs used.

Application of Electrochemical Techniques on Study of Effect of Nano-ZnO in Conductive Polyaniline Containing Zinc-Rich Primer

Effect of zinc oxide nanoparticles on anticorrosion performance has been studied in conductive polyaniline containing zinc-rich primer in 3.5 wt% NaCl solution, using Electrochemical Impedance Spectroscopy (EIS) and localized electrochemical Scanning Vibrating Electrode Technique (SVET). The results showed that the addition of nano-zinc oxide particles in conductive polyaniline containing zinc-rich primer made the reaction of zinc more stable and slower, further increasing the effective cathodic protection period. EIS and SVET results confirmed that three performance evolution stages were obtained for zinc-rich primer being immersed in 3.5 wt% sodium chloride solution.

New Ni-Anthracene Complex for Selective and Sensitive Detection of 2,4,6-Trinitrophenol

Selective and sensitive detection of explosive materials through a simple approach is an attractive area of research having implications on public safety and homeland security. Considering this implication in mind, a new Ni-anthracene complex was designed and synthesized and has been demonstrated as an efficient fluorescence chemosensor for the selective and sensitive detection of 2,4,6-trinitrophenol. Firstly, a fluorescent anthracene ligand (A) was synthesized by treating anthracene-9-carboxaldehyde with 1,3-diaminopropane in presence of a weak acid. To achieve superior selectivity and great quenching efficiency for 2,4,6-trinitrophenol (TNP), a Ni complex, namely, [Ni(μ2-L)(NO3)] (B), was synthesized via the reaction of A with Ni(NO3)2·6H2O. Complex B showed strong emission peak (λmax) at 412 nm and exhibited high selectivity towards TNP among other nitroaromatics and anions. 100 equivalents of TNP made 95% fluorescence quenching of B and its detection limit for TNP was calculated as 2.8 μM.

A Review on Applications of Two-Dimensional Materials in Surface-Enhanced Raman Spectroscopy

Two-dimensional (2D) materials, such as graphene and MoS2, have been attracting wide interest in surface enhancement Raman spectroscopy. This perspective gives an overview of recent developments in 2D materials’ application in surface-enhanced Raman spectroscopy. This review paper focuses on the applications of using bare 2D materials and metal/2D material hybrid substrate for Raman enhancement. The Raman enhancing mechanism of 2D materials will also be discussed. The progress covered herein shows great promise for widespread adoption of 2D materials in SERS application.

Application of Autofluorescence for Analysis of Medicinal Plants

Autofluorescence of secondary compounds contained in plant secretory cells may be applied to the analysis of medicinal plants for pharmacy. Emission and prevailing fluorescent pharmaceuticals have been estimated in several models of species such as Salvia officinalis, Berberis vulgaris, Humulus lupulus, and Matricaria chamomilla, by luminescence microscopy, microspectrofluorimetry, and confocal microscopy.

Fourier Spectroscopy: A Bayesian Way

The concepts of standard analysis techniques applied in the field of Fourier spectroscopy treat fundamental aspects insufficiently. For example, the spectra to be inferred are influenced by the noise contribution to the interferometric data, by nonprobed spatial domains which are linked to Fourier coefficients above a certain order, by the spectral limits which are in general not given by the Nyquist assumptions, and by additional parameters of the problem at hand like the zero-path difference. To consider these fundamentals, a probabilistic approach based on Bayes’ theorem is introduced which exploits multivariate normal distributions. For the example application, we model the spectra by the Gaussian process of a Brownian bridge stated by a prior covariance. The spectra themselves are represented by a number of parameters which map linearly to the data domain. The posterior for these linear parameters is analytically obtained, and the marginalisation over these parameters is trivial. This allows the straightforward investigation of the posterior for the involved nonlinear parameters, like the zero-path difference location and the spectral limits, and hyperparameters, like the scaling of the Gaussian process. With respect to the linear problem, this can be interpreted as an implementation of Ockham’s razor principle.

Determination of Metals Present in Textile Dyes Using Laser-Induced Breakdown Spectroscopy and Cross-Validation Using Inductively Coupled Plasma/Atomic Emission Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) was used for the quantitative analysis of elements present in textile dyes at ambient pressure via the fundamental mode (1064 nm) of a Nd:YAG pulsed laser. Three samples were collected for this purpose. Spectra of textile dyes were acquired using an HR spectrometer (LIBS2000+, Ocean Optics, Inc.) having an optical resolution of 0.06 nm in the spectral range of 200 to 720 nm. Toxic metals like Cr, Cu, Fe, Ni, and Zn along with other elements like Al, Mg, Ca, and Na were revealed to exist in the samples. The %-age concentrations of the detected elements were measured by means of standard calibration curve method, intensities of every emission from every species, and calibration-free (CF) LIBS approach. Only Sample 3 was found to contain heavy metals like Cr, Cu, and Ni above the prescribed limit. The results using LIBS were found to be in good agreement when compared to outcomes of inductively coupled plasma/atomic emission spectroscopy (ICP/AES).

Annular Beam Shaping in Multiphoton Microscopy to Reduce Out-of-Focus Background

Despite the inherent spatial confinement of multiphoton processes that arises from focusing through an objective, the maximum imaging depth in conventional multiphoton microscopy is ultimately limited by noise from out-of-focus fluorescence. This is particularly evident when imaging beyond shallow depths in highly scattering tissue as increased laser powers are necessary. The out-of-focus signal originates from multiphoton processes taking place primarily at shallow depths and deteriorates contrast and limits imaging depth. In this paper, annular laser beams are explored as a concept to reduce this background signal in multiphoton microscopy. The approach is theoretically verified by data from simulations and proof of principle is demonstrated on a custom-built experimental multiphoton microscopy platform. Annular laser beams were created by adopting wavefront control using a spatial light modulator and implemented for imaging tissue phantoms simulating turbid media and human skin ex vivo. The signal-to-background ratios were calculated and compared to images acquired with a traditional, filled-aperture Gaussian beam. Experiments in tissue phantom show an improvement in signal-to-background ratio of about 30% when using annular beam illumination in comparison to Gaussian illumination at specific depths. When laser power is not the limiting factor, this approach is expected to provide even greater benefits.

Nile Red and 2-NBDG Are Incompatible for the Simultaneous Detection of Lipid and Glucose Accumulation

Glucose is the universal energy source and a critical substrate for lipid synthesis in mammalian cells. Analysis of both glucose and lipid in cells is important for the understanding of the regulation of lipid synthesis in many cell types, but especially adipocytes, the major storage cell for fat in mammals. The fluorescent 7-nitrobenz-2-oxa-1,3-diazole (NBD) derivative of glucose, 2-NBDG, is used to monitor glucose uptake and the lipid-selective fluorophore Nile red is used to monitor lipid accumulation. Previous reports have used NBD-based fluorophores and Nile red simultaneously despite the possibility of spectral overlap. In this study, we determined if these fluorophores were experimentally compatible in preadipocytes and adipocytes stained with 2-NBDG and Nile red separately or costained. We found that Nile red is detectable in the wavelengths necessary to excite and detect 2-NBDG. This interference was further increased by the solvatochromic effect of lipid-localized Nile red. In addition, we found a synergistic increase in fluorescent intensity when both fluorophores were present. Unfortunately, even fine control of the excitation or emission wavelengths did not identify wavelengths suitable for selective detection when cells were costained. Therefore, 2-NBDG and Nile red cannot be used simultaneously—but can likely be used sequentially—to assess glucose uptake and lipid accumulation in lipid-laden cells.