Understanding the synergistic interaction between a 1,3,4-thiadiazole derivative and amphotericin B using spectroscopic and theoretical studies.

We present a comprehensive spectroscopic study supported by theoretical quantum chemical calculations conducted on a molecular system (4-(5-methyl-1,3,4-thiadiazol-2-yl)benzene-1,3-diol (C1) and the antibiotic Amphotericin B (AmB)) that exhibits highly synergistic properties. We previously reported the strong synergism of this molecular system and now wish to present related stationary measurements of UV-Vis absorption, fluorescence, and fluorescence anisotropy in a polar, aprotic solvent (DMSO and a PBS buffer), followed by time-resolved fluorescence intensity and anisotropy decay studies using different ratios of the selected 1,3,4-thiadiazole derivative to Amphotericin B. Absorption spectra measured for the system revealed discrepancies in terms of the shapes of absorption bands, particularly in PBS.

Spectral properties of 4-methylumbelliferone in PVA films; long-lived room temperature phosphorescence.

We studied absorption and fluorescence as well as room temperature phosphorescence (RTP) of 4-methylumbelliferone (4MU) in poly (vinyl alcohol) (PVA) films. We focused our study on the long-wavelength basic form of 4MU with absorption centered at 375 nm. The strong fluorescence with a quantum yield of above 70% appears at ∼430 nm.

Preliminary Investigation of a Potential Optical Biosensor Using the Diamond™ Nucleic Acid Dye Applied to DNA and Friction Ridge Analysis from Fingerprint Traces.

Developments in science and technology lead to an increasing use of scientific evidence in litigation. Interdisciplinary research can improve current procedures and introduce new ones for the disclosure and examination of evidence. The dactyloscopic trace is used for personal identification by matching minutiae (the minimum required may vary by country) or for extracting DNA material from the trace under investigation.

Room temperature luminescence of 1,N-etheno-2-aminopurine in poly (vinyl alcohol) films.

We studied spectral properties of 1,N-etheno-2-aminopurine after immobilization in poly (vinyl alcohol) films. The absorption spectrum of 1,N-ε2APu consists of two peaks centered at 300 and 370 nm, and the fluorescence spectrum has maximum at about 460 nm. The fluorescence quantum efficiency is 62%.

Photophysical Characterization and In Vitro Evaluation of α-Mangostin-Loaded HDL Mimetic Nano-Complex in LN-229 Glioblastoma Spheroid Model.

Cytotoxic activity has been reported for the xanthone α-mangostin (AMN) against Glioblastoma multiforme (GBM), an aggressive malignant brain cancer with a poor prognosis. Recognizing that AMN's high degree of hydrophobicity is likely to limit its systemic administration, we formulated AMN using reconstituted high-density lipoprotein (rHDL) nanoparticles. The photophysical characteristics of the formulation, including fluorescence lifetime and steady-state anisotropy, indicated that AMN was successfully incorporated into the rHDL nanoparticles.

Fiber-optics based fluorescence detection. Part I: Basic concepts.

Continuous in-line detection and process monitoring are essential for industrial, analytical, and biomedical applications. Lightweight, highly flexible, and low-cost fiber optics enable the construction of compact and robust hand-held devices forchemical and biological species analysis in both industrial and biomedical/detection. Despite the broad range of fiber-optic based applications, we lack a good understanding of the parameters that govern the efficiency of light collection or the sensitivity of detection.

Molecular Design Using Selected Concentration Effects in Optically Activated Fluorescent Matrices.

Molecular physics plays a pivotal role in various fields, including medicine, pharmaceuticals, and broader industrial applications. This study aims to enhance the methods for producing specific optically active materials with distinct spectroscopic properties at the molecular level, which are crucial for these sectors, while prioritizing human safety in both production and application. Forensic science, a significant socio-economic field, often employs hazardous substances in analyzing friction ridges on porous surfaces, posing safety concerns.

Photophysical properties of DAPI in PVA films. Possibility of room temperature phosphorescence.

We studied the spectral properties of 4'-6-diamidino-2-phenylindole (DAPI) in poly (vinyl alcohol) (PVA) films. Absorption and fluorescence spectra, emission and excitation spectra, quantum yield, and fluorescence lifetime have been characterized. An efficient room temperature phosphorescence (RTP) of DAPI has been observed with UV and blue light excitations.

Analysis of friction ridge evidence for trace amounts of paracetamol in various pharmaceutical industries by Raman spectroscopy.

The detection of potentially harmful substances presents a multifaceted challenge. On one hand, it can directly save lives, on the other, it can significantly aid and enhance police work, thereby increasing the effectiveness of investigations. The research conducted in this study primarily aims to identify paracetamol in fingerprints, considering situations involving direct contact of a person with paracetamol either chronically or in a single dose.

Effect of annealing on the room temperature luminescence of coumarin 106 in PVA films.

We studied the effect of annealing on the luminescence of Coumarin 106 (C106) in poly (vinyl alcohol) films (PVA films). The samples and reference polymer films were treated at temperatures between 100 °C and 150 °C (212 F and 302 F) for various times. After cooling and smoothing, the samples and references were measured at room temperature.

Multi intercalators FRET enhanced detection of minute amounts of DNA.

A novel approach is presented that increases sensitivity and specificity for detecting minimal traces of DNA in liquid and on solid samples. Förster Resonance Energy Transfer (FRET) from YOYO to Ethidium Bromide (EtBr) substantially increases the signal from DNA-bound EtBr highly enhancing sensitivity and specificity for DNA detection. The long fluorescence lifetime of the EtBr acceptor, when bound to DNA, allows for multi-pulse pumping with time gated (MPPTG) detection, which highly increases the detectable signal of DNA-bound EtBr.

Room temperature phosphorescence of 2-aminopyridine with direct triplet state excitation.

Phosphorescence emission at room temperature has been observed from 2-Aminopyridyne (2APi) embedded in poly (vinyl alcohol) (PVA) films. The gated emission with UV excitation at 305 nm results in a residual delayed fluorescence at around 350 nm and a broad phosphorescence spectrum with a maximum of around 500 nm. The phosphorescence excitation spectrum of 2APi - doped PVA film differs from the absorption spectrum in the long-wavelength part, showing a band at about 400-450 nm.

Room Temperature Phosphorescence of 5,6-Benzoquinoline.

Phosphorescence emission of 5,6-Benzoquinoline embedded in poly (vinyl alcohol) film has been studied at room temperature. A strong green long-lived emission was observed in films doped with 5,6-Benzoquinoline while illuminated on a UV plate. A broad phosphorescence emission spectrum is centered at about 500 nm.

Fluorescence measurements: importance of G-factor correction, magic angle, and observation wavelengths.

Excitation and emission (observation) conditions heavily impact fluorescence measurements. Both observed spectra and intensity decays (fluorescence lifetimes), when incorrectly measured, may lead to incorrect data interpretations. In this report, we discuss the role of observation conditions in steady-state and time-resolved (lifetime) fluorescence measurements.

Imaging and detection of long-lived fluorescence probes in presence of highly emissive and scattering background.

Optical biomedical imaging and diagnostics is a rapidly growing field that provides both structural and functional information with uses ranging from fundamental to practical clinical applications. Nevertheless, imaging/visualizing fluorescence objects with high spatial resolution in a highly scattering and emissive biological medium continues to be a significant challenge. A fundamental limiting factor for imaging technologies is the signal-to-background ratio (SBR).

Förster Resonance Energy Transfer-Enhanced Detection of Minute Amounts of DNA.

This article presents a novel approach to increase the detection sensitivity of trace amounts of DNA in a sample by employing Förster resonance energy transfer (FRET) between intercalating dyes. Two intercalators that present efficient FRET were used to enhance sensitivity and improve specificity in detecting minute amounts of DNA. Comparison of steady-state acceptor emission spectra with and without the donor allows for simple and specific detection of DNA (acceptor bound to DNA) down to 100 pg/μL.

Direct excitation of tryptophan phosphorescence. A new method for triplet states investigation.

We studied room temperature phosphorescence of tryptophan (TRP) embedded in poly (vinyl alcohol) films. With UV (285 nm) excitation, the phosphorescence spectrum of tryptophan appears at about 460 nm. We also observed the TRP phosphorescence with blue light excitation at 410 nm, well outside of the S→Sabsorption.

Non-excitonic defect-assisted radiative transitions are responsible for new D-type blinking in ternary quantum dots.

This work addresses the issue of dark states formation in QDs by cooperative excitonic and intrinsic defect-assisted radiative transitions. Here we refer to the observed blinking as D-type to distinguish it from purely excitonic types. It is shown experimentally that defect-assisted radiative relaxations in a single I-III-VI QD result in atypical blinking characteristics that cannot be explained on the basis of charged exciton models.

A novel approach to imaging and visualization of minute amounts of DNA in small volume samples.

This report presents a novel approach for detecting and visualizing small to trace amounts of DNA in a sample. By utilizing both the change in emission spectrum and change in fluorescence lifetime, there is a significant increase in detection sensitivity allowing for the imaging/visualizing of a picograms amount of DNA in a microliters volume. As in the previous reports, one of the oldest DNA intercalators, Ethidium Bromide (EtBr), is employed as a model system.

On the origin and correction for inner filter effects in fluorescence. Part II: secondary inner filter effect -the proper use of front-face configuration for highly absorbing and scattering samples.

Fluorescence is an established technology for studying molecular processes and molecular interactions. More recently fluorescence became a leading method for detection, sensing, medical diagnostics, biotechnology, imaging, DNA analysis, and gene expression. Consequently, precise and accurate measurements in various conditions have become more critical for proper result interpretations.

A novel approach for visualization and localization of small amounts of DNA on swabs to improve DNA collection and recovery process.

In this report, a simple and practical procedure is proposed for DNA localization on a solid matrix e.g., a collection swab.

On the possibility of direct triplet state excitation of indole.

We studied the luminescence properties of indole in poly (vinyl alcohol) (PVA) film. The indole molecules are effectively immobilized in this polymer film and display both fluorescence and phosphorescence emission at room temperature. We noticed that the phosphorescence of indole in PVA film can be effectively excited at a longer wavelength than its typical singlet to triplet population route involving intersystem crossing.

On the origin and correction for inner filter effects in fluorescence Part I: primary inner filter effect-the proper approach for sample absorbance correction.

Fluorescence technologies have been the preferred method for detection, analytical sensing, medical diagnostics, biotechnology, imaging, and gene expression for many years. Fluorescence becomes essential for studying molecular processes with high specificity and sensitivity through a variety of biological processes. A significant problem for practical fluorescence applications is the apparent non-linearity of the fluorescence intensity resulting from inner-filter effects, sample scattering, and absorption of intrinsic components of biological samples.

Probing the Assembly of HDL Mimetic, Drug Carrying Nanoparticles Using Intrinsic Fluorescence.

Reconstituted high-density lipoprotein (HDL) containing apolipoprotein A-I (Apo A-I) mimics the structure and function of endogenous (human plasma) HDL due to its function and potential therapeutic utility in atherosclerosis, cancer, neurodegenerative diseases, and inflammatory diseases. Recently, a new class of HDL mimetics has emerged, involving peptides with amino acid sequences that simulate the the primary structure of the amphipathic alpha helices within the Apo A-I protein. The findings reported in this communication were obtained using a similar amphiphilic peptide (modified via conjugation of a myristic acid residue at the amino terminal aspartic acid) that self-assembles (by itself) into nanoparticles while retaining the key features of endogenous HDL.

Photophysical properties of 2-Phenylindole in poly (vinyl alcohol) film at room temperature. Enhanced phosphorescence anisotropy with direct triplet state excitation.

We report the spectral properties of 2-Phenylindole (2PI) embedded in rigid poly (vinyl alcohol) (PVA) film. The 2PI in PVA film shows relatively strong and structured fluorescence with a maximum at 370 nm and surprisingly strong room temperature phosphorescence with an emission maximum of about 500 nm. The dye is highly immobilized in the polymer matrix, thus presenting high fluorescence anisotropy in an isotropic film of about 0.