Eliana
@ua.pt
Chemistry
Universidade de Aveiro
RESEARCH INTERESTS
CARBON NANOPARTICLES ANALYTICAL SENSORS OXYGEN AND NITROGEN REACTIVE SPECIES ATMOSPHERIC AEROOSOLS ENVIRONMENTAL & ANALYTICAL CHEMISTRY FLUORESCENCE SPECTROSCOPY FTIR SPECTROSCOPY UV-VIS SPECTROSCOPY
Scopus Publications
Scopus Publications
Andreia Ventura, Eliana F. C. Simões, Antoine S. Almeida, Roberto Martins, Armando C. Duarte, Susana Loureiro, and Regina M. B. O. Duarte
MDPI AG
Atmospheric aerosol deposition (wet and dry) is an important source of macro and micronutrients (N, P, C, Si, and Fe) to the oceans. Most of the mass flux of air particles is made of fine mineral particles emitted from arid or semi-arid areas (e.g., deserts) and transported over long distances until deposition to the oceans. However, this atmospheric deposition is affected by anthropogenic activities, which heavily impacts the content and composition of aerosol constituents, contributing to the presence of potentially toxic elements (e.g., Cu). Under this scenario, the deposition of natural and anthropogenic aerosols will impact the biogeochemical cycles of nutrients and toxic elements in the ocean, also affecting (positively or negatively) primary productivity and, ultimately, the marine biota. Given the importance of atmospheric aerosol deposition to the oceans, this paper reviews the existing knowledge on the impacts of aerosol deposition on the biogeochemistry of the upper ocean, and the different responses of marine biota to natural and anthropogenic aerosol input.
Eliana F.C. Simões, Antoine S. Almeida, Armando C. Duarte, and Regina M.B.O. Duarte
Elsevier BV
Abstract Reactive oxygen and nitrogen species (ROS and RNS) play a crucial role in biotic and abiotic processes. In the atmosphere, ROS/RNS are usually associated with air pollution. The ability of certain air particulate matter constituents to influence the formation and cycling of ROS/RNS at the atmosphere-biosphere-hydrosphere interfaces is important for the observed linkages between atmospheric aerosols and adverse health and climate effects. Atmosphere-hydrosphere ROS/RNS exchange fluxes affect the chemical composition of the atmosphere and surface waters compartments, acting both as a source and sink for ROS/RNS. Therefore, detecting and measuring ROS/RNS in this interface is of utmost importance. This article presents a critical review on the analytical challenges and limitations of the existing methodologies to measure ROS/RNS in air particles and surface waters. It also addresses the suitability of novel methodologies based on carbon nanoparticles as potential tools for the detection of ROS/RNS in atmospheric aerosols and aquatic compartments.
Eliana F.C. Simões, Luís Pinto da Silva, Joaquim C.G. Esteves da Silva, and João M.M. Leitão
Elsevier BV
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.
Guilherme P. C. Mello, Eliana F. C. Simões, Diana M. A. Crista, João M. M. Leitão, Luís Pinto da Silva, and Joaquim C. G. Esteves da Silva
Informa UK Limited
Abstract Diabetes mellitus is a chronic disease and leading cause of death worldwide, affecting more than 420 million people. High blood glucose levels are a common effect of uncontrolled diabetes, which can cause serious health damage. Diabetic individuals must measure their blood glucose levels regularly in order to control glycemic levels and minimize the effects of the disease. Glucose sensors have been used in the management of diabetes for more than 50 years, when Clark and Ann Lyons developed the first glucose enzyme electrode in 1962. Electrochemical sensors have become the leading technology for glucose concentration measuring with most of the commercially available devices being based on amperometric detection. However, the detection of glucose in the blood is still an object of intense research. The development of new fluorescent nanomaterials begins to constitute an alternative for glucose blood quantification. These sensors include carbon dots, quantum dots, graphene quantum dots, gold, silver and upconversion nanoparticles. This paper reviews the last 10 year fluorescent nanoparticles based technologies proposed for glucose monitoring and provide an insight into emerging optical fluorescence glucose biosensors.
Diana M. A. Crista, Guilherme P. C. Mello, Olena Shevchuk, Ricardo M. S. Sendão, Eliana F. C. Simões, João M. M. Leitão, Luís Pinto da Silva, and Joaquim C. G. Esteves da Silva
Springer Science and Business Media LLC
AbstractThe selective fluorescence sensing of fructose was achieved by fluorescence quenching of the emission of hydrothermal-synthesized carbon quantum dots prepared by 3-hydroxyphenylboronic acid. Quantification of fructose was possible in aqueous solutions with pH of 9 (Limit of Detection LOD and Limit of Quantification LOQ of 2.04 and 6.12 mM), by quenching of the emission at 376 nm and excitation ~380 nm with a linearity range of 0–150 mM. A Stern-Volmer constant (KSV) of 2.11 × 10−2 mM−1 was obtained, while a fluorescent quantum yield of 31% was calculated. The sensitivity of this assay towards fructose was confirmed by comparison with other sugars (such as glucose, sucrose and lactose). Finally, the validity of the proposed assays was further demonstrated by performing recovery assays in different matrixes.
Graphical Abstract
Eliana F.C. Simões, João M.M. Leitão, and Joaquim C.G. Esteves da Silva
Elsevier BV
Microwave synthetized sulfur and nitrogen co-doped carbon dots responded selectively to nitric oxide (NO) at pH 7. Citric acid, urea and sodium thiosulfate in the proportion of 1:1:3 were used respectively as carbon, nitrogen and sulfur sources in the carbon dots microwave synthesis. For this synthesis, the three compounds were diluted in 15 mL of water and exposed for 5 min to a microwave radiation of 700 W. It is observed that the main factor contributing to the increased sensitivity and selectivity response to NO at pH 7 is the sodium thiosulfate used as sulfur source. A linear response range from 1 to 25 μM with a sensitivity of 16 μM-1 and a detection limit of 0.3 μM were obtained. The NO quantification capability was assessed in standard and in fortified serum solutions.
Eliana F. C. Simões, João M. M. Leitão, and Joaquim C. G. Esteves da Silva
Springer Science and Business Media LLC
AbstractCarbon dots (CDs) were prepared from citric acid and urea, and their fluorescence was found to be quenched by hypochlorite and peroxynitrite. Microwave based synthesis gives CDs with excitation/emission wavelength-dependent quantum yields (8 % at 400/520 nm; 10 % at 360/451 nm; 12 % at 350/420 nm). Quenching of fluorescence depends on pH values, and response is most selective and sensitive to hypochlorite at pH 4, and to peroxynitrite at pH 9. The lower detection limits are 0.5 and 1.5 μM, respectively. The method was successfully applied to quantify hypochlorite and peroxynitrite in standard solutions and in spiked dilute serum samples.
Graphical abstractFluorescence quenching probes based in carbon dots nanoparticles prepared from citric acid and urea were developed for the quantification of hypochlorite at pH 4 and peroxynitrite at pH 9.
João M. M. Leitão, Eliana F. C. Simões, and Joaquim C. G. Esteves da Silva
Co-published with HEP
Eliana F.C. Simões, Joaquim C.G. Esteves da Silva, and João M.M. Leitão
Elsevier BV
Abstract The selective fluorescence sensing of nitric oxide (NO) and peroxynitrite anion (ONOO − ) in the presence of the principal reactive oxygen and nitrogen species (ROS/RNS) was achieved by fluorescence quenching through the pH variation of microwave synthesized fluorescent carbon dots (CDs) prepared from citric acid (CA) and ethylenediamine (EDA). The highest NO and ONOO − sensitivity, with the lowest sensitivity to the principal ROS/RNS, was demonstrated respectively at pH 4 and 10. The optimum synthesis and sensing conditions of CDs were obtained by multivariate full factorial experimental design methodologies: for NO, at pH 4, 2.5 g of CA and 1000 μL of EDA diluted in 15 mL of water exposed for 5 min to a microwave radiation of 700 W; for ONOO − , at pH 7, 10–0.25 g of CA and 500 μL of EDA diluted in 15 mL of water exposed for 5 min to a microwave radiation of 700 W. In these optimized conditions the synthesized CDs have a quantum yield about 40%. The quantification of NO at pH 4 and of ONOO − at pH 7 and 10 were done in standard and in fortified serum solutions. Also the quantification of NO and of ONOO − in standard solutions was performed in the presence respectively of ONOO − and NO.
Eliana F.C. Simões, Joaquim C.G. Esteves da Silva, and João M.M. Leitão
Elsevier BV
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.
Eliana F. C. Simões, João M. M. Leitão, and Joaquim C. G. Esteves da Silva
Springer Science and Business Media LLC
The quantification of nitric oxide (NO) based on the quenching of the fluorescence of a nanocomposites sensor constituted by cadmium/selenium quantum dots (CdSe) stabilized by chitosan (CS) and mercaptosuccinic acid (MSA) is assessed. The optimization of the response of the CS-CdSe-MSA nanocomposites to NO was done by multivariate response surface experimental design methodologies. The highest fluorescence quenching was obtained at pH 5.5 and at room temperature. The NO quantification capability of CS-CdSe-MSA was evaluated using standard solutions and a NO donor reagent. A large linear working range from 5 to 200 μM and a limit of detection of 1.86 μM were obtained. Better quantification results were obtained using the NO donor reagent. Besides NO, the response of the fluorescence of CS-CdSe-MSA to the main reactive oxygen and nitrogen species and similar NO compounds was also assessed.
Eliana F. C. Simões, João M. M. Leitão, and Joaquim C. G. Esteves da Silva
Springer Science and Business Media LLC
The effect on the fluorescence of the europium:tetracycline (Eu:Tc), europium:oxytetracycline (Eu:OxyTc) and europium:chlortetracycline (Eu:ClTc) complexes in approximately 2:1 ratio of nitric oxide (NO), peroxynitrite (ONOO−), hydrogen peroxide (H2O2) and superoxide (O2·−) was assessed at three ROS/RNS concentrations levels, 30 °C and pH 6.00, 7.00 and 8.00. Except for the NO, an enhancement of fluorescence intensity was observed at pH 7.00 for all the europium tetracyclines complexes—the high enhancement was observed for H2O2. The quenching of the fluorescence of the Tc complexes, without and with the presence of other ROS/RNS species, provoked by NO constituted the bases for an analytical strategy for NO detection. The quantification capability was evaluated in a NO donor and in a standard solution. Good quantification results were obtained with the Eu:Tc (3:1) and Eu:OxyTc (4:1) complexes in the presence of H2O2 200 μM with a detection limit of about 3 μM (Eu:OxyTc).
Eliana F. C. Simões, João M. M. Leitão, and Joaquim C. G. Esteves da Silva
Springer Science and Business Media LLC
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 (CFl); cobalt chloride concentration (CCoCl2); presence of oxygen (O2); and, the pH (pH). The concentration of sodium hydroxide (CNaOH) 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 - CFl from 0.50 to 1.56 mM, CCoCl2 from 0 to 1.252 × 10−2 M, pH from 6 to 8 and CNaOH 0.10 M. Better results were found in the presence of NO at pH 7.4, CFl 0.5 mM, without oxygen, without cobalt chloride and with a previous dilution of peroxynitrite solution with CNaOH 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.
Eliana F. C. Simões, João M. M. Leitão, Rui M. Barbosa, and Joaquim C. G. Esteves da Silva
Royal Society of Chemistry (RSC)
A fluorescence flow injection analysis (FIA) methodology for nitric oxide (NO) quantification was optimized by factorial analysis for the lowest limit of detection of nitric oxide. This methodology is based on the reaction of the NO with the non-fluorescent reduced fluoresceinamine given a high fluorescent oxidized fluoresceinamine. Box–Behnken and central composite optimization experimental design methodologies were used. The factors initially analysed by a screening experimental design methodology were the flow rate of the pump (Q), loop volume (L), reactor length (R), reduced fluoresceinamine concentration (CFl) and cobalt chloride concentration (CCoCl2). The response variables under analysis were the maximum fluorescence intensity, response repeatability and peak width. The optimum conditions were: one flow stream FIA configuration, Q = 0.60 mL min−1, L = 100 μL, R = 2 m, CFl = 1.50 mM and without CoCl2. A linear working range between 5 to 40 μM was evaluated with a limit of detection of 1.20 μM. Hydrogen peroxide, superoxide, nitrite and nitrate did not interfere with the NO detection. Good results were found in the quantification of NO liberated by a NO donor at pH 7.4 and in fortified serum samples.
João M. M. Leitão, Eliana F. C. Simões, and Joaquim C. G. Esteves da Silva
Royal Society of Chemistry (RSC)
A fluorescent derivatization reaction for Diltiazem drug quantification based on the condensation reaction of citric or malonic acid with acetic anhydride, catalyzed by the tertiary amine group of Diltiazem, was developed. Excitation emission matrices (EEMs) of fluorescence of the pure solvent (ethanol), standard and sample solutions following a standard addition methodology were analysed by PARAFAC based methods (PARAFAC, PARAFAC2 and PARALIND) to obtain robust calibration methodologies. The quantification results of the sample were compared with the official US Pharmacopeia high performance liquid chromatography-ultraviolet method (USP HPLC-UV). Although the experimental sets of EEM show linearity deviations all the PARAFAC based methods allow correct robust estimation of Diltiazem concentration in pharmaceutical formulations. The closest results were: derivatization with citric acid and PARAFAC2 six components non-negativity constraint model with a detection limit of 0.088 ppm; and, derivatization with malonic acid and PARAFAC six components non-negativity constraint model with a detection limit of 0.066 ppm for the malonic acid was observed. The simultaneous utilization of the three PARAFAC methods gives further information about the intrinsic structure of the data sets under analysis, i.e., it works as an efficient diagnostic tool for the existence of non-linearity and colinearity.
E. Simões, I. Abe, J. Oliveira, O. Frazão, P. Caldas, and J.L. Pinto
Elsevier BV
Abstract In this work is studied the response of optical fiber long period grating (LPG) to changes of the refractive index of the external media relatively to variations of wavelength and in transmission. The response of the LPG to refractive index greater and lesser than to cladding is investigated. A nanolayer was deposited onto the fiber to increase the sensitivity of the LPG to refractive index of the external media higher than cladding. The film modifies the rates of effective modes of cladding, thus improving the response of the changes in the refractive index of the external media higher than that in the refractive index of the cladding (ncl ≈ 1.457). The Langmuir–Blodgett technique was used for the deposition of the nanolayer.
I. Abe, J. Oliveira, E. Simões, P. Caldas, and O. Frazão
Elsevier BV
The analysis of the quality of food oils is of paramount importance, because the degradation of oils can lead to formation of harmful substances to the human organism. With the increase of the degradation of oils an increase of its refractive index occurs. The objective of this work is to develop and to characterize optical fiber refractometers sensitive to variations of refractive index of food oil samples. The optical fiber refractometers thanks to the intrinsic characteristics make them suitable for monitoring the quality of frying oils. They possess the advantages to require small volumes of sample for analysis, do not contaminate the sample, and supply the response in real time. In this work a long period grating (LPG) as refractometer is used because of their sensitivity to refractive index of the external media: degraded and not degraded frying oil samples. The oil samples had been characterized by the analysis of total polar components. The refractive index of oil is above 1.47, this region the LPG does not show enough sensitivity, a nanolayer of an organic material was coated onto the fiber. Using the Langmuir-Blodgett technique the response of LPG is modified according to the refractive index and thickness of the film. The deposition of the film modifies the rates effective modes of cladding, thus improving the response of the changes in the refractive index of the external media higher than that the refractive index of the cladding (n=1.457).
E. Simões, I. Abe, J. Oliveira, J. L. Pinto, P. Caldas, and O. Frazão
SPIE
In this work the behavior of an optical fiber Long Period Grating (LPG) refractometer with the variations of the surrounding refractive index is discussed. The objective is to characterize optical fiber refractometers sensitive to surrounding refractive index, higher and lower than the cladding. For values of surrounding refractive index higher than the cladding, the LPG does not show enough sensitivity. For this reason, a nanolayer of an organic material was coated onto the fiber, using the Langmuir-Blodgett technique. We characterized LPG covered with different nanolayers thickness (110 and 120 nm) relatively to changes in surrounding refractive index.