Seed priming is a potential tool for improving productivity under different environmental conditions. Aminolevulinic acid (ALA) priming can enhance plant tolerance to abiotic stresses, such as ...salinity, drought, and extreme temperatures. Nanopriming, priming with nanoparticles, can increase seed germination, growth, and plant development. The goal of this work was to compare the germination, growth, and development of sunflower seeds primed at 25 °C for 24 h with five treatments: water, ALA, silver, copper, and copper-silver nanoparticles (ALANPs) using a two-way analysis of variance. ALANPs were prepared by the photoreduction process (ALA as stabilizing/capping agent) and characterized by UV–Vis, transmission electron microscopy, FTIR, and Zeta potential. The germination percentage, shoot length, root length, seedling vigor index (Vi), and allometric coefficient were obtained on the 3rd, 6th, and 10th days after the priming process. The fluorescence spectra of chlorophyll extract of the whole seedling or directly in the cotyledons were measured. According to the results, seed priming with ALANPs enhanced sunflower seed germination capacity, seed growth, and increased chlorophyll production compared to water and ALA-primed seeds.
Pseudomonas aeruginosa is considered one of the most important pathogens that represent life‐threatening risk in nosocomial environments, mainly in patients with severe burns. Antimicrobial ...photodynamic therapy (aPDT) has been effective to kill bacteria. The purpose of this study was to develop a burn wound and bloodstream infection model and verify aPDT effects on it. In vitro, we tested two wavelengths (blue and red LEDs) on a clinical isolate of P. aeruginosa strain with resistance to multiple antibiotics using HB:La+3 as photosensitizer. Verapamil® associated to aPDT was also studied. In vivo, P. aeruginosa‐infected burned mice were submitted to aPDT. Bacterial counting was performed on local infection and bloodstream. Survival time of animals was also monitored. In this study, aPDT was effective to reduce P. aeruginosa in vitro. In addition, Verapamil® assay showed that HB:La+3 is not recognized by ATP‐binding cassete (ABC) efflux pump mechanism. In the in vivo study, aPDT was able to reduce bacterial load in burn wounds, delay bacteremia and keep the bacterial levels in blood 2–3 logs lower compared with an untreated group. Mice survival was increased on 24 h. Thus, this result suggests that aPDT may also be a novel prophylactic treatment in the care of burned patients.
This study reports a potential use of antimicrobial photodynamic therapy (aPDT) to delay bacteremia and increase life expectancy. We developed a mouse model of P. aeruginosa‐infected burns to investigate the effects of aPDT in situ and in the bloodstream. Infected mice without treatment died in 18 h. APDT was able to reduce bacterial load in burn wounds, retard bacteremia and keep the bacterial levels in blood 2–3 logs lower compared with untreated group. Mice survival was increased by 24 h. Put together, these findings suggest that aPDT could be a new prophylactic approach in the care of burned patients.
This work aims to investigate changes induced by low-energy radiation in adipose and muscular tissues employing autofluorescence and Raman spectroscopic techniques. X-ray beams expositions with 25 ...and 35 kV at 0.11, 1.1, and 2.1 Gy radiation dose levels were applied. Changes in Raman line intensities at specific bands assigned to collagen, proteins, and lipids were observed. Autofluorescent analysis exhibit variations in the collagen and nicotinamide adenine dinucleotide emission (NADH), resulting from the structural modifications, variations on the reduced/oxidized fluorophores equilibrium followed by radiation exposure. Results show that Raman and fluorescence spectroscopy are suitable techniques to evaluate radiation effects on biomolecules even at low radiation doses and energies.
Graphical Abstract
•Luminescence effects of Eu3+ in HAp nanocrystals induced by thermal treatments were investigated.•The energy transfer between Eu3+ (site I) to Eu3+ (site II) was observed and analyzed.•Eu3+ site ...distribution starts with 100% at site I for non-thermally treated nanocrystal.•Eu3+ ion gradually changes from site I symmetry to site II by thermal treatments.•Our study contributes for understanding the luminescence properties of nanophosphors.
In this work, we present the synthesis, characterization and the luminescence properties of Ca10(PO4)6(OH)2 (hydroxyapatite/HAp) nanocrystals doped with europium trivalent ions. The most important processes that lead to europium emissions in the visible region were identified. Eu:HAp nanopowder excited at 394nm (or 460nm) exhibits several emissions: (i) weak emissions at 579nm, 592nm and 616nm due to the 5D0→7F0, 5D0→7F1 and 5D0→7F2 transitions, respectively, with europium ion occupying site I in hydroxyapatite structure and (ii) strong emissions due to the 5D0→7F0 (574nm), 5D0→7F1 (602nm) and 5D0→7F2 (610–630nm) transitions, when Eu3+ is occupying site II. The emission spectrum and the time-resolved luminescence analysis showed that the HAp nanocrystals (nanopowder) thermally treated at temperature (T) between 500 and 800°C have a change in the initial Eu3+ site distribution of 100 % of Eu3+ at site I to a more stable one where the majority of europium ions are at site II: 30% remains at site I and 70% migrates to site II. In addition, an enhancement of the Eu3+ emission intensity is observed due to the increasing crystallite size. A time-resolved luminescence investigation using a short pulse laser excitation at 460nm was employed to measure the luminescence decays and to determine the most important mechanisms involved in the deexcitation process of 5D0 excited state of Eu3+, where it is seen a fast (2.9μs) energy transfer from Eu3+- site I (donor) to Eu3+- site II (acceptor) in the thermally treated nanopowders with T>500°C. The initial presence of 100% of Eu3+ at site I in the synthesized nanocrystals is gradually modified by the thermal treatments with temperatures above 500°C by thermal activation of Ca2+ vacancy (the charge compensator) diffusion through the HAp lattice, which propitiates the Ca2+- vacancies and Eu3+ ions to exchange positions in the lattice. By this thermal activated mechanism, Eu3+ ion migrates through the lattice until get the final distribution of 30% at site I and 70% at site II. As a result, the complete description of the Eu3+ (5D0) decay and the energy transfer process from Eu3+ (site I)→Eu3+ (site II) were proposed.
Silver nanoparticles (AgNPs) have been intensively studied for several purposes including therapeutic applications in cancer. When prepared with tryptophan and photoreduction, silver nanoparticles ...(TrpAgNPs) become an alternative to conventional anticancer drugs. In this study, the anticancer activity of synthesized TrpAgNPs against MCF-7 breast cancer cells was evaluated, and the inhibitory concentration (IC50) was found to be ~3.4 mg/mL. Since the protoporphyrin IX (PPIX) concentrations in tumor cells are elevate compared to normal cells, the PPIX-TrpAgNP interaction was studied to investigate if it could contribute for cell apoptosis. The investigation was performed using PPIX solution (0.9 μg/mL) with different TrpAgNP concentrations (from 0 to 13 mg/mL). PPIX was characterized by UV-Vis spectroscopy, steady-state and time-resolved fluorescence spectroscopy. The results have shown that the presence of spherical TrpAgNps with 16-nm diameter quench the PPIX fluorescence intensity. This quenching is strongly dependent on the concentration of the TrpAgNPs, and it is caused by a combination of a static and a dynamic process. The chemical binding leads to oxidation of tryptophan and formation of kynurenine, observed in the emission spectra around 470 nm. The strong reduction of the PPIX fluorescence decay lifetime with nanoparticle increasing concentration confirms the quenching processes due to charge transfer from the excited PPIX states to the resonant silver states. The present study confirms the anticancer activity of TrpAgNPs on the human breast cancer cell line (MCF-7) in vitro and indicates that PPIX-AgNP interaction could contribute with MCF-7 apoptosis.
Graphical abstract
Interaction between TrpAgNPs and PPIX
•Reduction is not depending on pulse intensity but on the second order dispersion.•Silver nanoparticles dimension reduction dependents on second order dispersion.•Nanoparticle dimension became ...smaller for negative second order dispersion.
The potential application of metallic nanoparticles had been attracting attention and interest from different areas of academia and industry. The nanoparticles properties and applications depend heavily on their dimension and shape, thus special interest is aimed to controlling the nanoparticles sizes. Ultrashort laser pulses are known to change metallic nanoparticles characteristics, but the interaction mechanism is still not completely understood. In this work we reduced the dimension of silver nanoparticles with ultrashort pulses and demonstrated that there is a dependence of the particles size on the second order dispersion introduced in the pulses, which became smaller as the dispersion becomes more negative. Based on the results, we propose that the Coulomb explosion that reduces the nanoparticles size is predominantly initiated by multiphotonic ionization for the intensities used (1014 W/cm2).
Normal prostate tissue contains high levels of citrate. In the presence of prostate cancer, the citrate level is diminished. In this paper we show that it is possible to use europium–oxytetracycline ...complex as a citrate fluorescent probe and consequently as a prostate cancer probe. We analyzed normal nude male mice urine and urine from nude male mice in which prostate cancer was induced by intraprostatic inoculation of DU145 cells. The urine samples were collected from the animals at the 7th, 14th, 21st, and 35th days after the surgery procedures. The intensity of europium emission at 615 nm in europium–oxytetracycline complex in the presence of citrate increases linearly. The citrate concentrations were determined from a calculated calibration curve. A concentration decrease in malignant prostate urine from the normal (PBS group) urine value from ∼8.0 mM to ∼2.4 mM (tumor group at 35th day) was found. The obtained results indicated that europium–oxytetracycline provides a significant biomarker for prostate cancer detection with a direct, accurate, noninvasive, and non-enzymatic method for measurement of citrate in biological fluids.
Hydroxyapatite (HA) doped with europium (HAEu) offers the advantage of making the hydroxyapatite a fluorescent biomarker, allowing their imaging through emission in vivo and in vitro tests. Several ...authors had been based their studies about europium site occupation (CaI and CaII) in hydroxyapatite by the lanthanide ion luminescence, verifying the influence of the method of synthesis and concentration of the dopant ion. In this study HA nanoparticles doped with 1.4 mol% of trivalent europium were synthesized by co-precipitation method and thermal treated at different temperatures (600°C and 1200°C). A careful evaluation of the influence of the excitation wavelength of europium luminescence in the HAEu was performed and it has been verified that both the characteristics transitions of europium, at CaI and CaII sites, and the luminescent intensity are dependent on the excitation wavelength. The non-observance of this fact can lead to erroneous conclusions about the site occupation of europium in hydroxyapatites.
In this work, fluorescence lifetime has been used to analyze protoporphyrin IX (PPIX) extracted from blood for diagnosing atherosclerosis. A total of 10 adult white male rabbits (New Zealand) were ...divided into the control group (CG), with a normal diet, and the experimental group (EG), subjected to a diet containing 1% cholesterol. Blood samples were collected from the animals, and protoporphyrin IX was extracted from the blood using acetone. The PPIX fluorescence lifetime (PPIXFL) was measured using time-correlated single photon counting, after excitation at 403nm from a pulsed laser diode. It was found that the PPIX emission intensity was enhanced in the animals that had received a hypercholesterolemic diet. The CG and EG animal's fluorescence decays were fitted by three exponentials and the mean lifetimes were 4.0ns and 9.5ns, respectively. This lifetime dependence resulted in a calibration curve that allows the determination of the PPIX concentration with a temporal measurement. The obtained results show that fluorescence lifetime can potentially be used as a noninvasive, simple, rapid, and sensitive tool in atherosclerosis diagnosis.
•Protoporphyrin IX photochemistry is affected by the atherosclerosis level.•PPIX fluorescence lifetime was measured using TCSPC.•Atherosclerotic plaques can be differentiated by lifetime fluorescence analysis of blood PPIX.•Determination of the PPIX concentration using calibration curve.
