Comparative investigation into the anticancer activity of analogs of marine coelenterazine and coelenteramine.

Cancer is still one of the most challenging diseases to treat, making the pursuit for novel molecules with potential anticancer activity an important research topic. Herein, we have performed a comparative investigation into the anticancer activity of analogs of marine coelenterazine and coelenteramine. The former is a well-known bioluminescent substrate, while the latter is a metabolic product of the resulting bioluminescent reaction. While both types of analogs showed anticancer activity toward lung and gastric cancer cell lines, we have obtained data that highlight relevant differences between the activity of these two types of compounds. More specifically, we observed relevant differences in structure-activity relationships between these types of compounds. Also, coelenteramine analogs showed time-dependent activity, while coelenterazine-based compounds usually present time-independent activity. Coelenterazine analogs also appear to be relatively safer toward noncancer cells than coelenteramine analogs. There was also seen a correlation between the activity of the coelenterazine-based compounds and their light-emission properties. Thus, these results further indicate the potential of the marine coelenterazine chemi-/bioluminescent system as a source of new molecules with anticancer activity, while providing more insight into their modes of action.

Effects of atmospheric pollutants (CO, O3, SO2) on the allergenicity of Betula pendula, Ostrya carpinifolia, and Carpinus betulus pollen.

Pollen of Betula pendula, Ostrya carpinifolia, and Carpinus betulus was exposed in vitro to relatively low levels of the air pollutants, namely carbon monoxide, ozone, and sulfur dioxide. The allergenicity of the exposed pollen was compared with that of non-exposed pollen samples to assess if air pollution exposition affects the allergenicity potential of pollen. The immunodetection assays indicated higher IgE recognition by all sera of allergic patients to the pollen protein extracts in all exposed samples in comparison to the non-exposed samples. These results show that the pollen exposition to low pollutants' levels induces increased allergic reaction to sensitized individuals.

Oxyluciferin photoacidity: the missing element for solving the keto-enol mystery?

The oxyluciferin family of fluorophores has been receiving much attention from the research community and several systematic studies have been performed in order to gain more insight regarding their photophysical properties and photoprotolytic cycles. In this minireview, we summarize the knowledge obtained so far and define several possible lines for future research. More importantly, we analyze the impact of the discoveries on the firefly bioluminescence phenomenon made so far and explain how they re-open again the discussion regarding the identity (keto or enol species) of the bioluminophore.

Antimicrobial Activity of Some Medicinal Herbs to the Treatment of Cutaneous and Mucocutaneous Infections: Preliminary Research.

(1) Background: Superficial, including cutaneous and mucocutaneous infections are a current public health problem with universal distribution. One of the main concerns, in the present/future, is fungal/bacterial infections by resistant microorganisms. This study aimed to verify if decoctions of coptidis (Coptis chinensis, Ranunculaceae family), neem (Azadirachta indica, Meliaceae family), and their essential oils (EOs), as well as the EO of manuka (Leptospermum scoparium, Myrtaceae family) have antimicrobial activity against prevalent species of microorganisms responsible for superficial infections. (2) Methods: The antimicrobial activity was determined by the minimum inhibitory concentration (MIC), using broth microdilution method, and minimum lethal concentration (MLC) was determined from subculture of MIC plates. (3) Results: C. chinensis EO and decoction demonstrated some antifungal action against the yeasts and dermatophytes tested. Greatest bactericidal effect against Propionibacterium acnes and some action against Staphylococcus aureus was observed. For A. indica only EO proved activity against dermatophytes and P. acnes. L. scoparium EO showed the broadest antimicrobial spectrum with activity against bacteria, yeasts, and dermatophytes showing greater activity against P. acnes and S. aureus. (4) Conclusions: C. chinensis (EO/decoction), EOs of L. scoparium and A. indica proved in vitro efficacy against fungal, bacterial, or mixed agents of superficial infections, either by sensitive or resistant strains.

Reduced fluoresceinamine for peroxynitrite quantification in the presence of nitric oxide.

A new fluorescent analytical methodology for the quantification of peroxynitrite (ONOO(-)) in the presence of nitric oxide (NO) was developed. The quantification of ONOO(-) is based in the oxidation of the non-fluorescent reduced fluoresceinamine to a high fluorescent oxidized fluoresceinamine in reaction conditions where the interference of NO is minimized. Screening factorial experimental designs and optimization Box-Behnken experimental design methodologies were used in order to optimize the detection of ONOO(-) in the presence of NO. The factors analysed were: reduced fluoresceinamine concentration (C( Fl)); cobalt chloride concentration (C(CoCl2)); presence of oxygen (O(2)); and, the pH (pH). The concentration of sodium hydroxide (C(NaOH)) needed to diluted the initially solution of ONOO(-) was also evaluated. An optimum region for ONOO(-) quantification where the influence of NO is minimal was identified - C(Fl) from 0.50 to 1.56 mM, C(CoCl2) from 0 to 1.252 × 10(-2) M, pH from 6 to 8 and C(NaOH) 0.10 M. Better results were found in the presence of NO at pH 7.4, C(Fl) 0.5 mM, without oxygen, without cobalt chloride and with a previous dilution of peroxynitrite solution with C(NaOH) 0.1 M. This methodology shows a linear range from 0.25 to 40 µM with a limit of detection of 0.08 µM. The bioanalytical methodology was successfully applied in the ONOO(-) quantification of fortified serum and macrophage samples.

Upconversion Emission Studies in Er3+/Yb3+ Doped/Co-Doped NaGdF4 Phosphor Particles for Intense Cathodoluminescence and Wide Temperature-Sensing Applications.

Er3+/Yb3+ doped/co-doped NaGdF4 upconversion phosphor nanoparticles were synthesized via the thermal decomposition route of synthesis. The α-phase crystal structure and nanostructure of these particles were confirmed using XRD and FE-SEM analysis. In the power-dependent upconversion analysis, different emission bands at 520 nm, 540 nm, and 655 nm were obtained. The sample was also examined for cathodoluminescence (CL) analysis at different filament currents of an electron beam. Through CL analysis, different emission bands of 526 nm, 550 nm, 664 nm, and 848 nm were obtained. The suitability of the present sample for temperature-sensing applications at a wide range of temperatures, from room temperature to 1173 K, was successfully demonstrated.

Theoretical modulation of the color of light emitted by firefly oxyluciferin.

One of the major mysteries regarding firefly bioluminescence is its pH-dependent multicolor variation. At basic pH, the emission is on the yellow-green region, whereas at acid pH, the light emission is observed on the red region of the visible spectrum. Theoretical calculations using density functional theory, molecular mechanics, and semiempirical methods were made to investigate the effect exerted by intermolecular forces on light emission, and their modulation by polarity, and the differences in the conformation of the active site at basic and acid pH. Red emission is achieved by the weakening of the interactions of the emitter with ionic and hydrophobic molecules, by the polarization of the benzothiazole microenvironment, by ionization of the enzyme-emitter complex and by changes of the hydrogen bond network. Arg220, Glu346, Ala350, Leu344 and adenosine-5'-monophosphate have blue-shifting effects, while His247, Phe249, Gly341, Thr253, and Ile288 exert a redshifting one.

Study on the effects of intermolecular interactions on firefly multicolor bioluminescence.

Firefly luciferase exhibits a color-tuning mechanism based on pH-induced changes in the structure of the active site. These changes increase the polarity of the active site, and thus modulate the intermolecular interactions between the light emitter and active site molecules. In this study, the effects exerted by adenosine monophosphate (AMP), water molecules, and amino acids of Luciola cruciata luciferase active site on the emission wavelength of oxyluciferin were assessed by TD-DFT calculations. The redshift results mainly from decreased interaction of oxyluciferin with AMP and increased interaction of the emitter with a water molecule and Phe249. Breaking of a hydrogen bond between the benzothiazole oxygen atom with formation of a similar bond to the thiazolone oxygen atom is also instrumental.

Kinetics of inhibition of firefly luciferase by dehydroluciferyl-coenzyme A, dehydroluciferin and L-luciferin.

The inhibition mechanisms of the firefly luciferase (Luc) by three of the most important inhibitors of the reactions catalysed by Luc, dehydroluciferyl-coenzyme A (L-CoA), dehydroluciferin (L) and L-luciferin (L-LH(2)) were investigated. Light production in the presence and absence of these inhibitors (0.5 to 2 µM) has been measured in 50 mM Hepes buffer (pH = 7.5), 10 nM Luc, 250 µM ATP and D-luciferin (D-LH(2), from 3.75 up to 120 µM). Nonlinear regression analysis with the appropriate kinetic models (Henri-Michaelis-Menten and William-Morrison equations) reveals that L-CoA is a non-competitive inhibitor of Luc (K(i) = 0.88 ± 0.03 µM), L is a tight-binding uncompetitive inhibitor (K(i) = 0.00490 ± 0.00009 µM) and L-LH(2) acts as a mixed-type non-competitive-uncompetitive inhibitor (K(i) = 0.68 ± 0.14 µM and αK(i) = 0.34 ± 0.16 µM). The K(m) values obtained for L-CoA, L and L-LH(2) were 16.1 ± 1.0, 16.6 ± 2.3 and 14.4 ± 0.96 µM, respectively. L and L-LH(2) are strong inhibitors of Luc, which may indicate an important role for these compounds in Luc characteristic flash profile. L-CoA K(i) supports the conclusion that CoA can stimulate the light emission reaction by provoking the formation of a weaker inhibitor.

Chemometric analysis of excitation emission matrices of fluorescent nanocomposites.

The performance of multivariate curve resolution (MCR-ALS) to decompose sets of excitation emission matrices of fluorescence (EEM) of nanocomposite materials used as analytical sensors was assessed. The two fluorescent nanocomposite materials were: NH(2)-polyethylene glycol (PEG200) functionalized carbon dots, sensible to aqueous Hg(II) (CD); and, CdS quantum dots attached to the dendrimer DAB, sensible to the ionic strength of the aqueous medium (CdS-DAB). The structures of these sets of EEM, obtained as function of the Hg(II) concentration and ionic strength, are characterized by collinear properties (CD) and non-linear spectral variations (CdS-DAB). MCR-ALS was able to detect that the source of the collinearities is the presence of different size CD that show similar affinity towards Hg(II). Moreover, MCR-ALS was able to model the non-linear spectral variations of the CdS-DAB that are induced by varying ionic strength. The chemometric pre-processing of the fluorescent data sets using soft-modelling multivariate curve resolution like MCR-ALS is a critical step to transform these nanocomposites with interesting fluorescent proprieties into analytical useful nanosensors.

Advanced Oxidation Processes Coupled with Nanomaterials for Water Treatment.

Water quality management will be a priority issue in the near future. Indeed, due to scarcity and/or contamination of the water, regulatory frameworks will be increasingly strict to reduce environmental impacts of wastewater and to allow water to be reused. Moreover, drinking water quality standards must be improved in order to account for the emerging pollutants that are being detected in tap water. These tasks can only be achieved if new improved and sustainable water treatment technologies are developed. Nanomaterials are improving the ongoing research on advanced oxidation processes (AOPs). This work reviews the most important AOPs, namely: persulfate, chlorine and NH2Cl based processes, UV/H2O2, Fenton processes, ozone, and heterogeneous photocatalytic processes. A critical review of the current coupling of nanomaterials to some of these AOPs is presented. Besides the active role of the nanomaterials in the degradation of water contaminants/pollutants in the AOPs, the relevance of their adsorbent/absorbent function in these processes is also discussed.

Reduced fluoresceinamine as a fluorescent sensor for nitric oxide.

A new fluorescent sensor for nitric oxide (NO) is presented that is based on its reaction with a non fluorescent substance, reduced fluoresceinamine, producing the highly fluorescent fluoresceinamine. Using a portable homemade stabilized light source consisting of 450 nm LED and fiber optics to guide the light, the sensor responds linearly within seconds in the NO concentration range between about 10-750 µM with a limit of detection (LOD) of about 1 µM. The system generated precise intensity readings, with a relative standard deviation of less than 1%. The suitability of the sensor was assessed by monitoring the NO generated by either the nitrous acid decomposition reaction or from a NO-releasing compound. Using relatively high incubation times, the sensor also responds quantitatively to hydrogen peroxide and potassium superoxide, however, using transient signal measurements results in no interfering species.

Hypochlorite fluorescence sensing by phenylboronic acid-alizarin adduct based carbon dots.

The selective fluorescence sensing of hypochlorite (ClO-) was achieved at pH 7.4 by a simple analytical procedure through the fluorescence quenching of autoclave synthesized carbon dots (CDs), which used as precursor an adduct formed between 3-aminophenylboronic acid (APBA) and alizarin red S (ARS). The use of this adduct allowed the preparation of CDs with a red shifted emission (560 nm) and excitation in the visible range (490 nm). Quantification of hypochlorite was achieved at physiological pH (pH 7.4) in aqueous solutions by fluorescence quenching with a linearity range of 0-200 µM (limit of detection of 4.47 µM, and limit of quantification of 13.41 µM). The selectivity of hypochlorite sensing was confirmed by comparison with other potential analytes, such as glucose, fructose and hydrogen peroxide. Finally, the validity of the proposed assay was further demonstrated by performing recovery assays in different matrices. Thus, this CDs allows the fluorescent sensing of ClO- with spectral properties more suitable for in vitro/in vivo applications.

An optimized luciferase bioluminescent assay for coenzyme A.

A new bioluminescent method for coenzyme A (CoA) quantification is described. It is based on the enzymatic conversion of dehydroluciferyl-adenylate (L-AMP) into dehydroluciferyl-coenzyme A (L-CoA) by firefly luciferase (E.C. 1.13.12.7) (LUC), which causes a flash of light that can be measured in a luminometer. The method was subjected to optimization using experimental design methodologies to obtain optimum values for the concentrations of L-AMP ([L-AMP]), luciferase ([LUC]), ATP ([ATP]) and luciferin ([LH(2)]). This method has a linear response over the range of 0.25-4 microM of CoA, with a limit of detection (LOD) of 0.24 microM and a limit of quantification (LOQ) of 0.80 microM. The assay has a relative standard deviation of about 7%. By coupling this optimized procedure to bioluminescent detection, a sensible and robust method can be obtained for the analysis of CoA.

Carbon dots on based folic acid coated with PAMAM dendrimer as platform for Pt(IV) detection.

Carbon quantum dots (CQDs) coated with poly(amidoamine) (PAMAM-NH2) dendrimer are prepared from folic acid and phosphoric acid under a hydrothermal procedure. The obtained nanoparticles are successfully used as fluorescent sensor for Pt(IV) (in the form of chloroplatinate ion). CQDs possess many attractive features including uniform dispersion with average size about 13nm for unmodified particles and, ∼30nm when they are coated with PAMAM-NH2 dendrimer. The synthesized nanoparticles have been characterized by elemental analysis, attenuated total reflectance (ATR), X-ray photoelectron (XPS) and Raman spectroscopies, transmission electron microscopy (TEM), dynamic light scattering (DLS), and steady-state and life-time fluorescence. CQDs are used as fluorescent sensor of Pt(IV) ion in aqueous media showing linear quenching effect of their fluorescence. The results obtained demonstrated a limit of detection of 657nM with an accuracy of the method of 0.13% (as RSD, n=10) and sensitivity of 78nM. Moreover, with the presence of other interference species, good results are obtained when applied in real samples from platinum nanoparticles synthesis. The dissolved platinum ions can be quantified in the range 6-96µM with an accuracy of 2.5%.

In vitro exposure of Ostrya carpinifolia and Carpinus betulus pollen to atmospheric levels of CO, O3 and SO 2.

Ostrya spp. and Carpinus spp. pollen was in vitro exposed to three atmospheric pollutants: CO, O3 and SO2. Two levels of each pollutant were used, and the first level corresponds to a concentration about the atmospheric hour-limit value acceptable for human health protection in Europe and the second level to about the triple of the first level. Experiments were done under artificial solar light with temperature and relative humidity controlled. The viability of the exposed pollen samples showed a significant decrease. Also, the germination percentage showed a significant decrease in both exposed pollens, and the effect was most pronounced for SO2, followed by O3 and CO. A general decreasing trend in the total soluble protein content of the exposed pollen samples when compared with the control was observed, but it was only statistically significant for the Ostrya spp pollen. The results showed marked effects were observed on the Ostrya spp. and Carpinus spp. pollen when exposed to air pollutant levels that can be considered safe for human health protection.

Carbon dots from tryptophan doped glucose for peroxynitrite sensing.

Tryptophan doped carbon dots (Trp-CD) were microwave synthesized. The optimum conditions of synthesizing of the Trp-CD were established by response surface multivariate optimization methodologies and were the following: 2.5 g of glucose and 300 mg of tryptophan diluted in 15 mL of water exposed for 5 min to a microwave radiation of 700 W. Trp-CD have an average size of 20 nm, were fluorescent with a quantum yield of 12.4% and the presence of peroxynitrite anion (ONOO(-)) provokes quenching of the fluorescence. The evaluated analytical methodology for ONOO(-) detection shows a linear response range from 5 to 25 µM with a limit of detection of 1.5 µM and quantification of 4.9 µM. The capability of the ONOO(-) quantification was evaluated in standard solutions and in fortified serum samples.

Study of the transformation of two salicylates used in personal care products in chlorinated water.

Disinfection of swimming pool water is essential to inactivate pathogenic microorganisms. However chlorine based disinfectants, the most commonly used, are known to lead to the formation of disinfection by-products (DBPs), some of which have been associated with adverse health effects. Precursors of DBPs include the organic matter present in the water used to fill the swimming pool, human body fluids and personal care products (PCPs) used by swimmers and bathers. The increased use, in the last years, of PCPs lead to an increased concern about the fate of PCPs in swimming pool waters and potential health risks of formed DBPs. In this study, the chemical transformations of two salicylates, benzyl salicylate (BzS) and phenyl salicylate (PS), incorporated in several PCPs, in chlorinated water were investigated. High-performance liquid chromatography (HPLC) with UV-diode-array detection (HPLC-UV-DAD) was used to follow the reaction kinetics and HPLC with mass spectrometry (HPLC-MS) was used to tentatively identify the major transformation by-products. Under the experimental conditions used in this work both salicylates reacted with chlorine following pseudo-first order kinetics: rate constant k = (0.0038 ± 0.0002) min(-1) and half-life t1/2 = (182 ± 10) min for BzS and rate constant k = (0.0088 ± 0.0005) min(-1) and half-life t1/2 = (79 ± 4) min for PS (mean ± standard deviation). The reactions of the two salicylates in chlorinated water led to the formation of DBPs that were tentatively identified as mono- and dichloro- substituted compounds. Most probably they result from an electrophilic substitution of one or two hydrogen atoms in the phenolic ring of both salicylates by one or two chlorine atoms.

Fingerprint detection and using intercalated CdSe nanoparticles on non-porous surfaces.

A fluorescent nanocomposite based on the inclusion of CdSe quantum dots in porous phosphate heterostructures, functionalized with amino groups (PPH-NH2@CdSe), was synthesized, characterized and used for fingerprint detection. The main scopes of this work were first to develop a friendly chemical powder for detecting latent fingerprints, especially in non-porous surfaces; their further intercalation in PPH structure enables not to spread the fluorescent nanoparticles, for that reason very good fluorescent images can be obtained. The fingerprints, obtained on different non-porous surfaces such as iron tweezers, mobile telephone screen and magnetic band of a credit card, treated with this powder emit a pale orange luminescence under ultraviolet excitation. A further image processing consists of contrast enhancement that allows obtaining positive matches according to the information supplied from a police database, and showed to be more effective than that obtained with the non-processed images. Experimental results illustrate the effectiveness of proposed methods.

Metal-enhanced photoluminescence from carbon nanodots.

In the last couple of years, carbon dots have emerged as a new novel luminescent particle for applications in fluorescence and microscopy in some ways analogous to quantum dots and silicon nanocrystals/particles. As with any fluorescent label or tag, absolute fluorescence intensity, brightness, and particle photostability are a primary concern. In this communication we subsequently show that similar to classical fluorophores, carbon dots located in the near-field, near to Plasmon supporting materials, show enhanced intensities and improved photostabilities.