Fluorescence Emission Data Research Articles

Ultrafast and Ultrasensitive Bacterial Detection in Biofluids: Leveraging Resazurin as a Visible and Fluorescent Spectroscopic Marker.

Here we report the application of chemometric analysis for modeling absorbance spectroscopy and fluorescence emission data from a resazurin-based assay targeting low-level bacterial detection in biofluids. Bacteria spiked samples were incubated with resazurin and absorbance and fluorescence data were collected at 30 min intervals. The absorbance data was subjected to Principal Component Analysis (PCA) and Partial Least Squares Regression (PLSR) and compared with the univariate fluorescence spectroscopy approach. The analysis demonstrated the multidimensional nature of the absorbance data, highlighting the appearance of the resorufin peak at the 2 h time point with a low bacterial inoculum of 0.01 CFU mL-1 across all the samples tested-water, urine and serum. The PLSR models supported the PCA data and exhibited strong predictive capabilities for water (RC2 = 0.937, RCV2 = 0.934), urine (RC2 = 0.899, RCV2 = 0.880) and serum (RC2 = 0.985, RCV2 = 0.967). Conversely, fluorescence is contingent upon resorufin existence, necessitating a prolonged waiting period postincubation with resazurin to verify the presence of bacteria, especially when contamination levels are low. Given the substantial global impact of bacteria-related infections, this method detects bacteria at low concentrations precisely and rapidly, improving efficiency and adaptability for point-of-care settings, promising swift diagnosis of bacterial infections, environmental monitoring, or food-quality control.

New anthracene-based Oxime-Palladium complexes loaded on albumin nanoparticles, in vitro cytotoxicity, mathematical release mechanism studies and biological macromolecules interaction investigation

In this research work, two new palladium complexes [trans-Pd(C15H10NOCH3)2]Cl2 (1) and [cis- Pd(C15H10NOCH3)(PPh3)2Cl]Cl (2) were synthesized using an alkoxyme ligand named isophethalaldoxime. Then structure characterization has been done by FT-IR and different NMR (1H, 13C and 31P) spectroscopy. Then, their interactions with biological macromolecules including deoxyribonucleic acid and bovine serum albumin were studied using various spectroscopic methods such as UV–Vis absorption, fluorescence emission spectroscopy and circular dichroism. The results showed the binding of the prepared complexes to the deoxyribonucleic acid via grooves and different binding sites of bovine serum albumin. Fluorescence emission data showed that the mechanism of extinction of albumin emission by these compounds is static. Competitive titration was performed on albumin with eosin-Y, ibuprofen and digoxin as site markers I, II and III. The antitumor activity and toxicity of these compounds were evaluated on cancer cell lines A549 (leukemia) and K562 by in-vitro cytotoxicity test. The IC50 values showed the good activity of these complexes in inhibiting cancer cells. In the last section, the release mechanism of synthesized complexes from albumin nanoparticles (BNPs) was investigated and theoretical calculations were performed that showed Korsmeyer-Peppas mechanism for complex (1) and Quadratic mechanism for complex (2).

Study of the interaction between polyphenol, quercetin and three micelles with different electric charges in acidic and aqueous media

The interactions between the polyphenol quercetin, Q, with three surfactant aggregates with different electric charges named micelles, were studied in aqueous solutions with pH values 4.7 and 7.0, to determine the following parameters: critical micellar concentration (CMC), micelle size and binding constant of the complex (Q-Micelle) proposing interaction sites for the formation of the complex. The surfactants used were: hexadecyltrimethyl ammonium bromide (cationic surfactant), CTAB, sodium dodecyl sulfate (anionic surfactant), SDS, and triton X-100 (non-ionic surfactant), TX100, used as Q fluorescence promoters to determine the CMC. The CMC values of the above surfactants at pH 4.7 were: 0.80 ± 0.10, 1.39 ± 0.07 and 0.59 ± 0.05 mM respectively, being lower than those reported in the water. With dynamic light scattering measurements, the hydrodynamic diameters of each micelle were calculated resulting in values of: 2.4 ± 0.5, 5.0 ± 1.1 and 8.4 ± 4.3 nm at pH 4.7 and: 2.1 ± 0.4, 4.9 ± 1.1 and 11.5 ± 4.1 nm at pH 7.0 respectively. In addition, the binding constants of the complex (Q-Micelle) with 1:1 stoichiometry were calculated from emission fluorescence data giving Log K values: 2.94 ± 0.02, 2.54 ± 0.02, and 3.63 ± 0.05 M-1 respectively. Finally, from the experimental data by UV–Vis spectrophotometry, the change in the behavior of the Q spectrum upon the addition of each of the surfactants to the system was analyzed, showing a decrease in absorbance when SDS and TX100 were added in an acidic medium, as a consequence of the photo-instability of the drug, suggesting that Q interacts with the outside of these micelles and is not fully incorporated inside them.

Physico-chemical and functional characteristics of neem seed protein isolate

The demands for plant-based proteins have increased, hence, the search for alternative sources for beneficial purposes. The physico-chemical and functional characteristics of protein isolated from neem seed were ascertained in this work. Neem seed protein isolate (NSPI) contained 86.33% protein rich in charged amino acids. Gel electrophoresis revealed that NSPI consists of polypeptides ranging from 97 to 21 kDa with 28–23 kDa components being prominent. Secondary structure data showed that β–sheets (45.83%) and α–helices (20.42%) were predominant in NSPI. The intrinsic fluorescence emission and surface hydrophobicity data indicated that at pH 3.0, NSPI was highly denatured and has less folded conformation. At pH 3.0 and 9.0, NSPI exhibited the highest protein solubility. NSPI had significantly (p<0.05) higher foaming and emulsifying capacities at pH 3.0. The oil and water holding abilities of NSPI were 3.17±0.09 and 1.72±0.17 g/g protein, respectively. Thus, NSPI could be considered a potentially good protein source for food formulations. Practical applicationsThe knowledge of the structure and function of a protein gives an insight into its potential applications in nutrition and wellness. The biochemical, physical, and functional properties of neem seed protein isolate such as the rich abundance of glutamic and aspartic amino acids and legumins, high arginine/lysine ratio, high solubility in acidic and alkaline conditions, and relatively high water and oil holding capacities make it a good protein source for food formulation and nutraceutical.

Synthesis of 3‐arylated chlorophyll‐a derivatives via Diels–Alder reaction and their atropisomerism

AbstractMethyl pyropheophorbides‐a possessing an o/m‐(methoxycarbonyl)phenyl group at the 3‐position were prepared by Diels–Alder reaction of 3‐(trans‐1,3‐butadienyl)chlorin with methyl propiolate and successive didehydrogenation of the resulting 1,4‐cyclohexadienes. The 3‐arylated chlorin bearing the sterically demanding o‐COOMe group as the major product was a 1:1 mixture of high‐performance liquid chromatography‐separable rotational isomers around the C3–C31 bond, while the minor product with the m‐COOMe was less sterically hindered to exhibit rapid atropisomerization at room temperature. The 3‐aryl group of the major product was nearly perpendicular to the chlorin π‐system and less conjugated with the chlorin moiety than that of the minor product wherein more π‐conjugation occurred to give slightly red‐shifted Qy bands. Although both the atropisomers of the o‐substitute in dichloromethane showed similar visible absorption bands and fluorescence emission data, their circular dichroism bands in the ultraviolet‐C light region were dependent on the stereochemistry.

Improved monitoring of cryptogam gas-exchange and volatile emissions during desiccation-rehydration cycles with a within-chamber hydration method

Desiccation-rehydration studies in cryptogams constitute an important tool to understand the relation of key physiological traits with species stress tolerance and environmental adaptability. Real-time monitoring of responses has been limited by the design of commercial or custom measuring cuvettes and difficulties in experimental manipulation. We developed a within-chamber rehydration method that allows to rewater the samples rapidly, without the need to open the chamber and take out the sample for manual rehydration by the investigator. Data is collected in real-time and simultaneously with an infrared gas-analyzer (LICOR-7000), a chlorophyll fluorometer (Maxi Imaging-PAM) and a proton transfer reaction time-of-flight mass-spectrometer (PTR-TOF-MS) for volatile organic compound emissions. The system was tested on four cryptogam species with contrasting ecological distributions. No major errors or kinetics disruptions were found during system testing and measurements. Our within-chamber rehydration method improved accuracy, as measurement periods were not lacking, and repeatability of the protocol by reducing error variance in sample manipulation. This method provides an improved technique to conduct desiccation-rehydration measurements, contributing to the standardization and accuracy of current existing methodologies. A close real-time and simultaneous monitoring of photosynthesis, chlorophyll fluorescence and volatile organic compound emission data, offers a novel perspective in the analysis of the cryptogam stress responses that is yet to be fully explored.

Spectrofluorimetric in tandem with principal component analysis for characterizing mycobacterium tuberculosis disease

In this study, fluorescence spectroscopy (FS) in tandem with the chemometric technique has effectively been used for analyzing respiratory infectious disease Mycobacterium tuberculosis. This research work is based on the fluorescence emission of bacterium grown in acid-fast bacillus (AFB) culture. Samples were collected from TB suspected patients of various areas of Khyber Pakhtunkhwa, and cultured in the Provisional TB Reference Lab, Hayatabad Medical Complex Peshawar, Pakistan. The fluorescence spectra from all these samples have been acquired using the 405 nm wavelength as excitation. The differences in the fluorescence emission spectra between TB positive, TB negative, and cultured media samples has been found at peak emission wavelengths arising at 467 nm and 490 nm. The differences between TB positive and negative samples were seen both in the intensities as well as shift in their fluorescence emission peaks. For highlighting the spectral differences, principal component analysis (PCA) is applied on the fluorescence emission data collected from the three sets of samples. PCA clearly cluster the data into three different groups based on features extracted from their fluorescence emission data. These results are novel and suggest that FS can be used as alternate confirmation tool of mycobacterium through AFB culture on a mass scale. Furthermore, this technique is fast, cost effective and user friendly that could be used effectively for the early detection of mycobacterium bacillus in the suspected individual.

Colloidal synthesis of cesium iodide nanocrystals for visible-enhanced photodetection applications

In this study, cesium iodide (CsI) nanoparticles were synthesized for the first time by pulsed laser ablation in ethanol at various laser fluences . The structural and optical properties of the CsI nanoparticles were studied as a function of laser fluence. The x-ray diffraction (XRD) results confirm the formation of crystalline CsI with a cubic structure along (110) plane. The optical absorbance spectra showed two absorption peaks at 291 and 363 nm. The optical energy gap of CsI NPs decreases as laser fluence increases. Transmission electron microscope studies show that the synthesized nanoparticles have a spherical shape and the mean particle size prepared at 22.9, 33.1 and 43.3 J/cm 2 was 23, 25, and 28 nm, respectively. Scanning electron microscope results reveal the formation of nanosized spherical CsI nanoparticles. The fluorescence emission data of CsI shows two main bands centered at 339 nm and 387 nm. Raman spectra show three Raman peaks located at 15, 26 and 44 cm −1 . The zeta potential results confirm that the CsI NPs prepared at 33.1 J/cm 2 have good stability. The current-voltage characteristics of CsI/Si heterojunctions show rectification properties, and the illuminated current-voltage shows that the maximum photocurrent was found for a photodetector fabricated at 33.1 J/cm 2 . The maximum responsivity and detectivity of the photodetector are 1.66 A/W and 5.5 × 1012 Jones at 400 nm, respectively, for a photodetector prepared at 33.1 J/cm 2 . A quantum efficiency of 5.16 × 10 2 % at 400 nm is reached for a photodetector prepared at 33.1 J/cm 2 . The Hall effect shows that the synthesized CsI NPs are p-type and the highest hole mobility was found for a sample prepared at 33.1 J/cm 2 . • Colloidal Cesium iodide nanoparticles were synthesized by laser ablation in liquid. • The effect of laser fluence on the properties of CsI was investigated. • Different morphologies of CsI nanocrystals were obtained. • High performance CsI nanostructure/Si photodetector was fabricated.

Synthesis and structural analysis of push-pull imidazole-triazole based fluorescent bifunctional chemosensor for Cu2+ and Fe2+ detection

Fluorescent imidazole-triazole based ligands L1 and L2 have been designed as chemical push-pull chemosensors for divalent metal ions and synthesized through palladium-catalyzed cross-coupling reactions using indium organometallics and click chemistry. The novel ligands exhibit intense absorption in the ultraviolet region with high molar extinction coefficients, and strong fluorescence emission with large Stokes displacements. On the basis of UV–Vis absorption spectroscopy and fluorescence emission data in acetonitrile, L1 is shown as a bifuncional chemosensor with differential response for Fe2+ and Cu2+ over a range of selected 3d divalent and other metal ions. The binding site of the ligand was established by single-crystal X-ray diffraction and 1H NMR spectroscopy studies. The association constants, determined by spectrofluorimetric titrations, show a steady binding affinity of L1 for Cu2+ and Fe2+ in comparison with other previously reported fluorescent bidentate chemosensors, offering the lowest limit of detection (LOD) with Cu2+. DFT calculations provide a rationale properly understanding and interpreting the experimentally observed results. Indeed, a mechanism of the different optical responses of L1 towards 3d divalent metal ions is proposed.

Stability of Insulin on Polycaprolactone Nanoparticles as a Function of Surface Properties

The purpose of this research was to formulate insulin-loaded polycaprolactone (PCL) nanoparticles and evaluate structural stability of the protein using fluorescence spectroscopy. The size and morphology of the nanoparticles were characterized using dynamic light scattering (DLS) and scanning electron microscopy (SEM). Fluorescence emission data revealed that insulin is most stable with multilayer adsorption at pH close to its isoelectric point (IEP). The obtained particle size ranged from 130-140 nm+22 (SD). The loading amount of insulin onto the PCL nanoparticles was low at pH 7.4 and relatively high at pH 5.3. The adsorption phenomenon of protein onto hydrophobic nanoparticles provides a promising noninvasive carrier system for insulin.

Elucidation of specific binding sites and extraction of toxic Gen X from HSA employing cyclodextrin

The presence of per and poly-fluoroalkyl substances (PFAS), commonly referred to as forever chemicals, in aquatic systems is a serious global health problem. While the remediation of PFAS from aqueous media has been extensively investigated, their interactions with and removal from biological systems have received far less attention. We report herein structural alterations to human serum albumin (HSA) upon addition of perfluoro(2-methyl-3-oxahexanoic) acid (Gen X) monitored by changes to the fluorescence and circular dichroism (CD) spectra of HSA. The equilibrium association constant for Gen X binding to HSA is 7( ± 1) × 103 M−1 determined from changes in HSA fluorescence emission data during titration. Site-specific HSA binding fluorophores, 8-anilinonaphthalene-1-sulfonic acid (1,8-ANS), warfarin and dansyl-L-proline were used to investigate the specific binding sites of Gen X on HSA. A competitive displacement study yields association constants for Gen X to HSA at the 1,8-ANS, warfarin, and dansyl-L-proline binding sites to be 6.25 ( ± 0.5) × 104 M−1, 1.1 × 106 M−1, and 2.5( ± 0.2) × 109 M−1 respectively. Addition of β-cyclodextrin (β-CD) and heptakis(6-deoxy-6-amino)-β-cyclodextrin heptahydrochloride to the HSA:Gen X complex leads to the effective extraction of Gen X from the complex with the return of HSA in its native form. Gen X also leads to displacement of site-specific binding fluorophores bound to HSA, while subsequent addition of β-CD extracts Gen X from HSA with the return of the characteristic fluorescence of the HSA bound site-specific agent. These results illustrate the strong and specific binding sites of Gen X on HSA and demonstrate the principles for the potential application of β-CD for the remediation of PFAS from biological systems.

Highly selective fluorescent peptide-based chemosensors for aluminium ions in aqueous solution.

Two novel fluorescent peptide-based chemosensors, including A (2-amino-benzoyl-Ser-Glu-Glu-NH2) and B (2-amino-benzoyl-Ala-Glu-Pro-Glu-Ala-Glu-Pro-NH2) were synthesized and characterized by nuclear magnetic resonance (NMR) spectra. These fluorescent probes exhibited excellent selective and sensitive responses to Al3+ ions over other metal ions in aqueous buffered solutions. The limits of detection for both chemosensors towards the Al3+ ions were in the order of ∼10-7M (A: 155nM and B: 195nM), which clearly indicates that these probes have significant potential for biological applications. They also displayed high binding affinity (1.3029 × 104M-1 and 1.7586 × 104M-1 relevant to A and B respectively). These two chemosensors are great analytical probes that produce turn-on responses upon binding to Al3+ ions through an intramolecular charge transfer (ICT) mechanism. In addition, the application of both chemosensors was examined over a wide range of pH. The fluorescent peptide-based probes and Al3+ form a 1:1 coordination complex according to the ESI-MS and Job's plot analysis. Notably, upon addition of Al3+ to these chemosensors, a fluorescence enhancement of approximately 8-fold was observed and the binding mode was determined using NMR titration and fluorescence emission data.

Discovering New Lipidomic Features Using Cell Type Specific Fluorophore Expression to Provide Spatial and Biological Specificity in a Multimodal Workflow with MALDI Imaging Mass Spectrometry.

Identifying the spatial distributions of biomolecules in tissue is crucial for understanding integrated function. Imaging mass spectrometry (IMS) allows simultaneous mapping of thousands of biosynthetic products such as lipids but has needed a means of identifying specific cell-types or functional states to correlate with molecular localization. We report, here, advances starting from identity marking with a genetically encoded fluorophore. The fluorescence emission data were integrated with IMS data through multimodal image processing with advanced registration techniques and data-driven image fusion. In an unbiased analysis of spleens, this integrated technology enabled identification of ether lipid species preferentially enriched in germinal centers. We propose that this use of genetic marking for microanatomical regions of interest can be paired with molecular information from IMS for any tissue, cell-type, or activity state for which fluorescence is driven by a gene-tracking allele and ultimately with outputs of other means of spatial mapping.

The Molecular Mechanism of Ca2+ Triggered DREAM Dimerization

Downstream Regulatory Element Antagonist Modulator (DREAM) belongs to the family of neuronal calcium sensor proteins that are expressed in the central nervous system including the hippocampus and the neural cortex. DREAM interacts with a variety of intracellular partners, and is involved in regulating gene expression, kinetics of potassium channels, calcium homeostasis, and enzymatic activity of presenilin; it was proposed to be involved in several physiological processes such as memory, learning and pain sensitivity; and linked to pathological conditions such as Alzheimer's and Huntington's disease. Previous studies have indicated that calcium association to DREAM leads to the formation of a Ca2+ bound dimer, while in the apo state a monomer-tetramer equilibrium was observed. In order to better understand Ca2+ triggered dimerization process, we prepared a chimeric version of DREAM (DREAM-NCS1) with Arg 200/Arg 220, and Leu 158/Leu 159 replaced by residues corresponding to the analogues residues in NCS-1, with the aim to remove salt bridges and hydrophobic interactions stabilizing DREAM dimer. DREAM-NCS1 properties were investigated using molecular dynamic simulations and spectroscopic approaches. Fluorescence emission data shows a distinct reorganization of W169 environment upon Ca2+ binding to DREAM-NCS1, with respect to WT, whereas enhancement in the emission of DREAM-NCS: 1,8-ANS complex points towards an increased exposure of the hydrophobic sites in the chimeric protein. Furthermore, low polarization values for DREAM-NCS1 bound to peptides mimicking site 1 and site 2 in the T1 domain of Kv channels are consistent with the lower affinity of the chimeric protein for each site as well as with the presence of the DREAM-NCS-1 monomeric form in the presence of Ca2+. These data points towards the role of both, hydrophobic interactions and salt bridges in stabilizing the dimeric form of the protein as well as in propagating allosteric signals.

Synthesis of Cationic Pyridinium–Chlorin Conjugates with Various Counter Anions and Effects of the Anions on Their Photophysical Properties

Abstract Cationic pyridinium pending chlorophyll-a derivatives with several counter anions were synthesized by Ag(I)-induced oxidation reactions of methyl pyropheophorbide-a possessing the 3-vinyl group with pyridine. The high water-solubility of the synthetic 31-pyridinio-3-vinyl-chlorin cation with a chloride anion resulted in efficient anion exchange reactions conducted in a biphasic system of H2O and CH2Cl2. Using either or both of the two synthetic procedures, ten salts were successfully synthesized with SbF6−, PF6−, BF4−, ClO4−, (CF3SO2)2N−, CF3SO3−, NO3−, I−, Br−, and Cl−. The effects of the counter anions on the physical properties of the cationic chlorophyll-a derivatives were discussed using their 1H NMR, visible absorption, and fluorescence emission data as well as theoretical model calculations. Although the visible absorption and fluorescence emission spectra were changed faintly, the fluorescence quantum yields and lifetimes were dependent on the counter anions, showing that the anions affected the pyridinium group acting as an electron-acceptor and the fluorescence quenching by intramolecular charge transfer.

Synthetic substituted boronates of dihydroxy-bacteriochlorin absorbing and emitting far-red to near-infrared light as bacteriopheophytin-a analogs

Several substituted boronates of methyl cis-7,8-dihydroxy-pyrobacteriopheophorbide-a possessing the same 3-acetyl-131-oxo-bacteriochlorin π-conjugated system as bacteriopheophytin-a found in type-II reaction centers of anoxygenic photosynthetic bacteria were prepared by chemical modification of chlorophyll-a. The semisynthetic bacteriochlorins are less oxidizable to chlorins and more readily available from natural phototrophs than the above natural bacteriochlorin, while the formers show similar optical properties in solution as the latter. All the boronate pigments efficiently absorb near ultraviolet, green, and far-red light and strongly emit light in a far-red to near-infrared region. Their electronic absorption and fluorescence emission data are nearly independent of the alkyl and (hetero)aromatic substituents at the boron atom.

Palladium-Catalyzed Acylation of Terminal Alkynes toward 3-Ynone-Linked Chlorophyll-a Derivatives and Their Optical Properties.

The Pd-catalyzed acylation reactions of terminal 3-ethynyl moieties of chlorophyll-a (Chl-a) derivatives are described herein. Both acyl chlorides and acid anhydrides were valuable reagents for the coupling, resulting in the formation of π-conjugation extended Chl-a derivatives possessing a carbonyl-ethynyl group at the C3-position. The ultraviolet-visible absorption and fluorescence emission data were obtained in solution to evaluate the optical properties of the 3-ynone-linked Chl-a derivatives.

Coupled Excited-State Dynamics in N-Substituted 2-Methoxy-9-Acridones.

Fluorophores of the acridone family have been widely employed in many applications, such as DNA sequencing, the detection of biomolecules, and the monitoring of enzymatic systems, as well as being the bases of intracellular sensors and even antitumoral agents. They have been widely used in fluorescence imaging due to their excellent photophysical properties, in terms of quantum yield and stability. However, frequently, the fluorescence emission data from acridones are not easily interpretable due to complex excited-state dynamics. The formation of π-stacking aggregates and excimers and excited-state proton transfer (ESPT) reactions usually result in emission features that are dependent on the experimental conditions. Therefore, an in-depth understanding of the dynamics involved in the excited-state transients of these dyes is mandatory for their appropriate application. Herein, we synthesized and fully characterized different 2-methoxy-9-acridone dyes. Their transient fluorescence emission spectra exhibited a complex dynamic behavior that can be linked to several excited-state reactions. We performed a thorough study of the excited-state dynamics of these dyes by means of time-resolved fluorimetry supported by computational calculations. All this allowed us to establish a multistate kinetic scheme, involving an ESPT reaction coupled to an excimer formation process. We have unraveled the rich dynamics behind this complex behavior, which provides a better understanding of the excited states of these dyes.

An excitation emission fluorescence lifetime spectrometer using a frequency doubled supercontinuum laser source

The accurate fluorescence analysis of complex, multi-fluorophore containing proteins requires the use of multi-dimensional measurement techniques. For the measurement of intrinsic fluorescence from tyrosine (Tyr) and tryptophan (Trp) one needs tuneable UV excitation and for steady-state measurements like Excitation Emission Matrix (EEM) simple pulsed Xe lamps are commonly used. Unfortunately, simultaneous multi-dimensional wavelength and time resolved measurement of intrinsic protein fluorescence in the 260 to 400 nm spectral range are challenging and typically required the use of very complex tuneable laser systems or multiple single excitation wavelength sources. Here we have assembled and validated a novel Excitation Emission Fluorescence Lifetime Spectrometer (EEFLS) using a pulsed, frequency doubled, Super-Continuum Laser (SCL) source coupled with a 16 channel multi-anode Time Correlated Single Photon Counting (TCSPC) measurement system. This EEFLS enabled the collection of near complete lifetime and intensity maps over the most important intrinsic protein fluorescence spectral range (λex = 260–350/λem = 300–500 nm). The 4-dimensional (λex/λem/I(t)/τ) Excitation Emission Fluorescence Lifetime Matrix (EEFLM) data produced can be used to better characterize the complex intrinsic emission from proteins. The system was capable of measuring fluorescence emission data with high spectral (1–2 nm) resolution and had an Instrument Response Function (IRF) of ∼650 ps for accurate measurement of nanosecond lifetimes. UV power output was stable after a warm up period, with variations of <2% over 9 hours and reproducible (relative standard deviation RSD < 1.5%). This enabled the collection of accurate EEFLM data at low resolution (∼12 nm in excitation and emission) in 1–2 hours or high resolution (4 nm) in ∼17 hours. EEFLS performance in the UV was compared with a conventional commercial TCSPC system using pulsed LED excitation and validated using solutions of p-terphenyl and tryptophan.

Spectroscopic characterization of amphorae from the 8th to the 7th c. BCE found at the Almaraz settlement in Almada, Portugal

The archaeological site of Almaraz is located in the old part of the city of Almada, in the south shore of Tagus River, region of Lisbon. The excavated findings and the radiocarbon dating of the contexts where these were found show an occupation that can in fact be dated from the 8th to the 7th c. BCE period, thus a very early stage of the Phoenician occupation in the Iberian Peninsula. Numerous amphorae sherds were found at Almaraz. A spectroscopic characterization of those ceramics was made and is presented here, to help us understand if they were produced locally, in Lisbon workshops, or imported.Sixteen sherds representative of the thousands found at Almaraz were studied with the use of non-invasive spectroscopies, namely by crossing information from micro-Raman and X-ray fluorescence emission data. X-ray diffraction experiments were also performed.In spite of the fact that no ceramic kilns were found at Almaraz until now, the results point to two major groups of amphorae of local origin: one which used clays of Miocene origin, found on the southern shores of the Tagus River, very close to the Almaraz site, at Palença (with quartz, anorthite, diopside and hematite). Another group, remarkably different, made use of clays of Pliocene origin also from the Tagus Estuary, the Fontaínhas clay source (where quartz, anorthite, muscovite and hematite were found).