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1.
Talanta ; 270: 125603, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38194860

RESUMO

The present work introduces two novel approaches to fabricate simple and cost-effective pH and temperature probes. Sinusoidal voltage methodologies were employed to electrodeposit polyaniline (PANI) at different growth times (10-20 min) on the surface of an affordable Sonogel-Carbon electrode to conform a robust pH sensor. The presence of PANI and its phases were corroborated by electrochemical means. The sensibility, reversibility and selectivity of the produced sensor were very adequate to apply it in physiological samples. In this regard, the proposed sensor was evaluated in artificial blood serum as well as untreated plasma samples obtaining outstanding results in comparison with a gold reference technique (error <2 %). In addition, a new composite sonogel material, intrinsically modified with multiwalled carbon nanotubes, was attached on top of an electrode couple to one-step fabricate a new temperature probe, relating resistance of the probe with the surroundings temperature. In this case, an optical microscopy characterization was performed to study the sturdiness of the layer. Remarkably, suitable results in terms of sensitivity and selectivity were obtained. The probes were assessed in artificial and untreated plasma samples as well, with the corresponding validation step (error <1 %) by using a commercial temperature probe.

2.
Chemosphere ; 350: 141039, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38147923

RESUMO

Sulfonamides are among the widespread bacterial antibiotics. Despite this, their quick emergence constitutes a serious problem for ecosystems and human health. Therefore, there is an increased interest in developing relevant detection method for antibiotics in different matrices. In this work, a straightforward, green, and cost-effective protocol was proposed for the preparation of a selective molecularly imprinted membrane (MIM) of sulfamethoxazole (SMX), a commonly used antibiotic. Thus, cellulose acetate was used as the functional polymer, while polyethylene glycol served as a pore-former. The developed MIM was successfully characterized through scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The MIM was used as a sensing platform in conjunction with a smartphone for optical readout, enabling on-site, selective, and highly sensitive detection of SMX. In this way, a satisfactory imprinting factor of around 3.6 and a limit of detection of 2 ng mL-1 were reached after applying response surface methodologies, including Box-Behnken and central composite designs. Besides, MIM demonstrated its applicability for the accurate and selective detection of SMX in river waters, wastewater, and drugs. Additionally, the MIM was shown to be a valuable sorbent in a solid-phase extraction protocol, employing a spin column setup that offered rapid and reproducible results. Furthermore, the developed sensing platform exhibited notable regeneration properties over multiple cycles and long shelf-life in different storage conditions. The newly developed methodology is of crucial importance to overcome the limitations of classical imprinting polymers. Furthermore, the smartphone-based platform was used to surpass the typically expensive and complicated methods of detection.


Assuntos
Antibacterianos , Impressão Molecular , Humanos , Impressão Molecular/métodos , Sulfametoxazol , Espectroscopia de Infravermelho com Transformada de Fourier , Ecossistema , Extração em Fase Sólida/métodos , Polímeros/química , Adsorção
3.
Biosensors (Basel) ; 13(8)2023 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-37622916

RESUMO

The separation of enantiomers plays a critical role in pharmaceutical development, ensuring therapeutic efficacy, safety, and patent protection. It enables the production of enantiopure drugs and enhances our understanding of the properties of chiral compounds. In this study, a straightforward and effective chiral detection strategy was developed for distinguishing between tryptophan (TRP) enantiomers. The approach involved the preparation of a magnetic molecularly imprinted chitosan (MMIC) for preparation of the sample, which was combined with a nitrocellulose membrane (a paper-based analytical device, PAD) integrated with D-TRP covalently grafted with polymethacrylic acid (PAD-PMA_D-TRP). Discriminating between the TRP enantiomers was achieved using AuNPs as a colorimetric probe. Indeed, the presence of D-TRP rapidly induced the aggregation of AuNPs due to its strong affinity to PAD-PMA_D-TRP, resulting in a noticeable change in the color of the AuNPs from red to purple. On the other hand, L-TRP did not induce any color changes. The chiral analysis could be easily performed with the naked eye and/or a smartphone. The developed method exhibited a detection limit of 3.3 µM, and it was successfully applied to detect TRP in serum samples, demonstrating good recovery rates. The proposed procedure is characterized by its simplicity, cost-effectiveness, rapidity, and ease of operation.


Assuntos
Quitosana , Nanopartículas Metálicas , Ouro , Smartphone , Triptofano , Fenômenos Magnéticos
4.
STAR Protoc ; 4(3): 102501, 2023 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-37590151

RESUMO

We present a protocol for generating a precise deletion, without altering the genetic background of the strain, of a transposable element (TE) in a natural population of Drosophila melanogaster using two steps of CRISPR-Cas9 homology-directed repair. We describe steps for replacing the TE by a fluorescent marker and for subsequent marker removal using single-guide RNAs, repair plasmids, and microinjection. We also detail steps for screening the deletion of the TE and generating a homozygous mutant strain. For complete details on the use and execution of this protocol, please refer to Merenciano and Gonzalez.1.

5.
Biosensors (Basel) ; 13(7)2023 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-37504077

RESUMO

The authors present a novel sensing platform for a disposable electrochemical, non-enzymatic glucose sensor strip at physiological pH. The sensing material is based on dendritic gold nanostructures (AuNs) resembling feather branches, which are electrodeposited onto a laser-scribed 3D graphene electrode (LSGE). The LSGEs were fabricated via a one-step laser scribing process on a commercially available polyimide sheet. This study investigates several parameters that influence the morphology of the deposited Au nanostructures and the catalytic activity toward glucose electro-oxidation. The electrocatalytic activity of the AuNs-LSGE was evaluated using cyclic voltammetry (CV), linear sweep voltammetry (LSV), and amperometry and was compared to commercially available carbon electrodes prepared under the same electrodeposition conditions. The sensor demonstrated good stability and high selectivity of the amperometric response in the presence of interfering agents, such as ascorbic acid, when a Nafion membrane was applied over the electrode surface. The proposed sensing strategy offers a wide linear detection range, from 0.5 to 20 mM, which covers normal and elevated levels of glucose in the blood, with a detection limit of 0.21 mM. The AuNs-LSGE platform exhibits great potential for use as a disposable glucose sensor strip for point-of-care applications, including self-monitoring and food management. Its non-enzymatic features reduce dependence on enzymes, making it suitable for practical and cost-effective biosensing solutions.


Assuntos
Técnicas Biossensoriais , Grafite , Nanoestruturas , Técnicas Eletroquímicas , Eletrodos , Glucose , Ouro/química , Grafite/química , Lasers , Nanoestruturas/química
6.
Foods ; 12(9)2023 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-37174286

RESUMO

There is an increasing interest in food science for high-quality natural products with a distinct geographical origin, such as saffron. In this work, the excitation-emission matrix (EEM) and synchronous fluorescence were used for the first time to geographically discriminate between Moroccan saffron from Taroudant, Ouarzazate, and Azilal. Moreover, to differentiate between Afghan, Iranian, and Moroccan saffron, a unique fingerprint was assigned to each sample by visualizing the EEM physiognomy. Moreover, principal component analysis (LDA) and linear discriminant analysis (LDA) were successfully applied to classify the synchronous spectra of samples. High fluorescence intensities were registered for Ouarzazate and Taroudant saffron. Yet, the Azilal saffron was distinguished by its low intensities. Furthermore, Moroccan, Afghan, and Iranian saffron were correctly assigned to their origins using PCA and LDA for different offsets (Δλ) (20-250 nm) such that the difference in the fluorescence composition of the three countries' saffron was registered in the following excitation/emission ranges: 250-325 nm/300-480 nm and 360-425 nm/500-550 nm. These regions are characterized by the high polyphenolic content of Moroccan saffron and the important composition of Afghan saffron, including vitamins and terpenoids. However, weak intensities of these compounds were found in Iranian saffron. Furthermore, a substantial explained variance (97-100% for PC1 and PC2) and an important classification rate (70-90%) were achieved. Thus, the non-destructive applied methodology of discrimination was rapid, straightforward, reliable, and accurate.

7.
Mikrochim Acta ; 190(5): 168, 2023 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-37012526

RESUMO

A new electrochemical sensor device has been developed through the modification of a polyaniline-silicon oxide network with carbon black (CB). Enhanced electrical conductivity and antifouling properties have been achieved due to the integration of this cheap nanomaterial into the bulk of the sensor. The structure of the developed material was characterized using Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy techniques. Cyclic voltammetry was used to characterize electrochemically the Sonogel-Carbon/Carbon Black-PANI (SNG-C/CB-PANI) sensor device. In addition, differential pulse voltammetry was employed to evaluate the analytical response of the sensor towards sundry chlorophenols, common environmental hazards in aqueous ecosystems. The modified sensor material showed excellent antifouling properties, which led to a better electroanalytical performance than the one displayed with the bare sensor. Notably, a sensitivity of 5.48 × 103 µA mM-1 cm-2 and a limit of detection of 0.83 µM were obtained in the determination of 4-chloro-3-methylphenol (PCMC) at a working potential of 0.78 V (vs. 3 M Ag/AgCl/KCl), along with proficient values of reproducibility and repeatability (relative standard deviation < 3%). Finally, the analysis of PCMC was carried out in multiple validated water samples using the synthesized SNG-C/CB-PANI sensor device, obtaining excellent results of recovery values (97-104%). The synergetic effect of polyaniline and carbon black leads to novel antifouling and electrocatalytic effects that improve the applicability of this sensor in sample analysis versus complex conventional devices.

8.
Org Biomol Chem ; 21(3): 590-599, 2023 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-36545812

RESUMO

A copper-iron-based catalyst has been prepared by a low-temperature co-precipitation and sonication method. The use of high-energy ultrasound reduces the time required for the preparation process from one workweek to one day with respect to the catalysts obtained by conventional coprecipitation and thermal treatment methods. The resulting material has been characterized at compositional, textural, structural, and chemical levels by ICP-AES, BET, SEM-EDS, XRD, TEM, and FTIR among other techniques. The material shows catalytic activity in the acyloxylation reaction of 1,4-dioxane and cyclohexene under microwave irradiation. In parallel with the optimized catalyst synthesis, the use of microwaves allowed for a substantial improvement in the outcome of the reaction in terms of cleanliness, yield, and time.


Assuntos
Cobre , Ferro , Cobre/química , Micro-Ondas , Cicloexenos
9.
Sensors (Basel) ; 22(21)2022 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-36366146

RESUMO

Reusable Sonogel-Carbon electrodes containing carbon black (SNGC-CB) have been used for the electrochemical analysis of caffeic acid (CA) in real matrices. Measurements were firstly performed in standard solutions, in which SNGC-CB electrodes allowed the electrochemical determination of CA with high sensitivity and low limit of detection, equal to 0.76 µM. The presence of CB nanostructures in the formulation led to improved performances with respect to pristine SNGC electrodes. Then, measurements were performed in four instant coffees of different brands. A comparison between the results obtained by electrochemical, chromatographic and spectroscopic methods showed that SBGC-CB electrodes represent a simple and economic tool for the rapid assessment of caffeic acid-related molecules in instant coffees.


Assuntos
Carbono , Café , Carbono/química , Eletrodos , Ácidos Cafeicos/análise , Ácidos Cafeicos/química , Técnicas Eletroquímicas/métodos , Limite de Detecção
10.
Biosensors (Basel) ; 12(11)2022 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-36354428

RESUMO

Monitoring of lactate is spreading from the evident clinical environment, where its role as a biomarker is notorious, to the agrifood ambit as well. In the former, lactate concentration can serve as a useful indicator of several diseases (e.g., tumour development and lactic acidosis) and a relevant value in sports performance for athletes, among others. In the latter, the spotlight is placed on the food control, bringing to the table meaningful information such as decaying product detection and stress monitoring of species. No matter what purpose is involved, electrochemical (bio)sensors stand as a solid and suitable choice. However, for the time being, this statement seems to be true only for discrete measurements. The reality exposes that real and continuous lactate monitoring is still a troublesome goal. In this review, a critical overview of electrochemical lactate (bio)sensors for clinical and agrifood situations is performed. Additionally, the transduction possibilities and different sensor designs approaches are also discussed. The main aim is to reflect the current state of the art and to indicate relevant advances (and bottlenecks) to keep in mind for further development and the final achievement of this highly worthy objective.


Assuntos
Técnicas Biossensoriais , Ácido Láctico , Humanos
11.
Food Chem ; 393: 133417, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-35691065

RESUMO

A fast, precise and inexpensive alternative for evaluating the antioxidant activity (AA) in walnut kernel extracts is proposed. Traditional ABTS assay and an electrochemical index approach have been applied to evaluate the AA in walnuts. A fast and efficient defatting of the walnuts by ultrasound assisted extraction (UAE) was carried out. Later, for the extraction of polyphenolic compounds, a procedure based on UAE in ethanolic medium was used. The AA of the sample ethanolic extracts was expressed as both % of inhibition by the ABTS spectrophotometric method and the electrochemical index approach (EI) obtained by the ratio between current and potential peak values using differential pulse voltammetry (DPV) at a Sonogel-Carbon electrode. The behaviour of the EI approach have been explored using six polyphenols standards and walnut kernel extracts at pH 2. All the polyphenols appeared at an oxidation potential between 0.476 and 0.778 V. Eleven samples available to consumers were analysed. A high significant correlation (R2 = 0.927) between the spectrophotometric measurements and the EI approach of the walnut extracts was obtained.


Assuntos
Antioxidantes , Juglans , Antioxidantes/química , Flavonoides/química , Juglans/química , Extratos Vegetais/química , Polifenóis/química
12.
Cancers (Basel) ; 14(7)2022 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-35406407

RESUMO

INTRODUCTION: Treatment for advanced ovarian cancer (AOC) comprises cytoreductive surgery combined with chemotherapy. Multimodal prehabilitation programmes before surgery have demonstrated efficacy in postoperative outcomes in non-gynaecological surgeries. However, the viability and effects of these programmes on patients with AOC are unknown. We aimed to evaluate the feasibility and postoperative impact of a multimodal prehabilitation programme in AOC patients undergoing surgery. METHODS: This single-centre, before-and-after intervention pilot study included 34 patients in two cohorts: the prehabilitation cohort prospectively included 15 patients receiving supervised exercise, nutritional optimisation, and psychological preparation from December 2019 to January 2021; the control cohort included 19 consecutive patients between January 2018 and November 2019. Enhanced Recovery After Surgery guidelines were followed. RESULTS: The overall adherence to the multimodal prehabilitation programme was 80%, with 86.7% adherence to exercise training, 100% adherence to nutritional optimisation, and 80% adherence to psychological preparation. The median hospital stay was shorter in the prehabilitation cohort (5 (IQR, 4-6) vs. 7 days (IQR, 5-9) in the control cohort, p = 0.04). Differences in postoperative complications using the comprehensive complication index (CCI) were not significant (CCI score: 9.3 (SD 12.12) in the prehabilitation cohort vs. 16.61 (SD 16.89) in the control cohort, p = 0.08). The median time to starting chemotherapy was shorter in the prehabilitation cohort (25 (IQR, 23-25) vs. 35 days (IQR, 28-45) in the control cohort, p = 0.03). CONCLUSIONS: A multimodal prehabilitation programme before cytoreductive surgery is feasible in AOC patients with no major adverse effects, and results in significantly shorter hospital stays and time to starting chemotherapy.

13.
Nat Commun ; 13(1): 1948, 2022 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-35413957

RESUMO

High quality reference genomes are crucial to understanding genome function, structure and evolution. The availability of reference genomes has allowed us to start inferring the role of genetic variation in biology, disease, and biodiversity conservation. However, analyses across organisms demonstrate that a single reference genome is not enough to capture the global genetic diversity present in populations. In this work, we generate 32 high-quality reference genomes for the well-known model species D. melanogaster and focus on the identification and analysis of transposable element variation as they are the most common type of structural variant. We show that integrating the genetic variation across natural populations from five climatic regions increases the number of detected insertions by 58%. Moreover, 26% to 57% of the insertions identified using long-reads were missed by short-reads methods. We also identify hundreds of transposable elements associated with gene expression variation and new TE variants likely to contribute to adaptive evolution in this species. Our results highlight the importance of incorporating the genetic variation present in natural populations to genomic studies, which is essential if we are to understand how genomes function and evolve.


Assuntos
Elementos de DNA Transponíveis , Drosophila , Animais , Elementos de DNA Transponíveis/genética , Drosophila/genética , Drosophila melanogaster/genética , Evolução Molecular , Expressão Gênica , Análise de Sequência de DNA
14.
Anal Chim Acta ; 1203: 339709, 2022 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-35361431

RESUMO

Molecularly imprinted polymers that mimic the binding mechanism of antibodies and their antigens exhibit several advantages, such as fast synthesis, low cost, high stability, and allow to overcome the ethical issues associated with antibody farming in animals. Herein, a novel strategy combining the magnetic molecularly imprinted polymer (MMIP) as an artificial antibody with a fluorescence procedure for the detection of quercetin in plant samples was designed. The MMIP was synthesized via a radical polymerization process to recognize specific functional groups of quercetin using a green technique based on high energy ultrasound irradiation. The developed MMIP was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning/transmission electron microscopy, and thermal gravimetric analysis, which confirmed the successful preparation of MMIP. The adsorption capacity and selectivity of the MMIP for quercetin and other interferents analogous were performed. The MMIP was applied in the solid-phase extraction (SPE) technique as a selective sorbent for the sample preparation. Besides, a sensitive fluorometric method for the quantitation of quercetin was developed. A linear response was obtained within the concentration of 0.005-1.25 µg mL-1 of quercetin. The limit of detection and quantitation were 1.1 ng mL-1 and 3.7 ng mL-1, respectively. The average recoveries for quercetin were between 92.2% and 104.7% with an RSD less than 5.06% in spiked orange juice and tea extract samples. Furthermore, the developed procedure was successfully combined with a new paper-based analytical device for on-site smartphone analysis of quercetin.


Assuntos
Impressão Molecular , Animais , Fenômenos Magnéticos , Magnetismo , Impressão Molecular/métodos , Polímeros Molecularmente Impressos , Quercetina
15.
Genome Res ; 32(1): 189-202, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34965939

RESUMO

Anopheles coluzzii is one of the primary vectors of human malaria in sub-Saharan Africa. Recently, it has spread into the main cities of Central Africa threatening vector control programs. The adaptation of An. coluzzii to urban environments partly results from an increased tolerance to organic pollution and insecticides. Some of the molecular mechanisms for ecological adaptation are known, but the role of transposable elements (TEs) in the adaptive processes of this species has not been studied yet. As a first step toward assessing the role of TEs in rapid urban adaptation, we sequenced using long reads six An. coluzzii genomes from natural breeding sites in two major Central Africa cities. We de novo annotated TEs in these genomes and in an additional high-quality An. coluzzii genome, and we identified 64 new TE families. TEs were nonrandomly distributed throughout the genome with significant differences in the number of insertions of several superfamilies across the studied genomes. We identified seven putatively active families with insertions near genes with functions related to vectorial capacity, and several TEs that may provide promoter and transcription factor binding sites to insecticide resistance and immune-related genes. Overall, the analysis of multiple high-quality genomes allowed us to generate the most comprehensive TE annotation in this species to date and identify several TE insertions that could potentially impact both genome architecture and the regulation of functionally relevant genes. These results provide a basis for future studies of the impact of TEs on the biology of An. coluzzii.


Assuntos
Anopheles , Malária , Animais , Anopheles/genética , Elementos de DNA Transponíveis/genética , Humanos , Malária/genética , Mosquitos Vetores/genética , População Urbana
16.
Sensors (Basel) ; 21(24)2021 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-34960563

RESUMO

In this work, template-free nanostructured conducting polymers (nCPs)-embedded gold nanoparticles (AuNPs) from aniline, thiophene and 3,4-ethylenedioxythiophene have been prepared via a one-pot sonochemical method. The synthesis of the nanocomposite (nCPs-AuNPs) was achieved in a short period of time (5-10 min), by applying high-energy ultrasound to an aqueous mixture of a CP precursor monomer and KAuCl4, in the presence of LiClO4 as dopant. The synthesis process is simpler, greener and faster in comparison to other procedures reported in the literature. Remarkably, bulk quantities of doped polyaniline PANI-AuNPs nanofibers were obtained. Subsequently, they were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR), as well as by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). PANI-AuNPs nanofibers were also employed as immobilization matrix for a benchmark enzyme, glucose oxidase (GOX). Finally, glucose was determined in real samples of white and red wines by using the so-obtained GOX-PANI-AuNPs/Sonogel-Carbon biosensor, providing outstanding recoveries (99.54%). This work may offer important insights into the synthesis of nanostructured conducting polymers and also stimulates the exploration of the applications of these nanocomposites, especially in research fields such as (bio)sensors, catalysis and composite materials.


Assuntos
Nanopartículas Metálicas , Nanofibras , Compostos de Anilina , Ouro
17.
Sensors (Basel) ; 21(15)2021 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-34372213

RESUMO

Conducting polymers (CPs) are extensively studied due to their high versatility and electrical properties, as well as their high environmental stability. Based on the above, their applications as electronic devices are promoted and constitute an interesting matter of research. This review summarizes their application in common electronic devices and their implementation in electronic tongues and noses systems (E-tongues and E-noses, respectively). The monitoring of diverse factors with these devices by multivariate calibration methods for different applications is also included. Lastly, a critical discussion about the enclosed analytical potential of several conducting polymer-based devices in electronic systems reported in literature will be offered.


Assuntos
Técnicas Biossensoriais , Polímeros , Nariz Eletrônico , Eletrônica , Língua
18.
Sensors (Basel) ; 21(12)2021 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-34207281

RESUMO

Silica-based electrodes which permanently include a graphite/Au nanoparticles composite were tested for non-enzymatic detection of glucose and fructose. The composite material showed an effective electrocatalytic activity, to achieve the oxidation of the two analytes at quite low potential values and with good linearity. Reduced surface passivation was observed even in presence of organic species normally constituting real samples. Electrochemical responses were systematically recorded in cyclic voltammetry and differential pulse voltammetry by analysing 99 solutions containing glucose and fructose at different concentration values. The analysed samples consisted both in glucose and fructose aqueous solutions at pH 12 and in solutions of synthetic musts of red grapes, to test the feasibility of the approach in a real frame. Multivariate exploratory analyses of the electrochemical signals were performed using the Principal Component Analysis (PCA). This gave evidence of the effectiveness of the chemometric approach to study the electrochemical sensor responses. Thanks to PCA, it was possible to highlight the different contributions of glucose and fructose to the voltammetric signal, allowing their selective determination.


Assuntos
Grafite , Nanopartículas Metálicas , Técnicas Eletroquímicas , Eletrodos , Frutose , Glucose , Ouro , Limite de Detecção , Análise Multivariada , Dióxido de Silício
19.
J Chem Phys ; 154(18): 184501, 2021 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-34241040

RESUMO

Deep eutectic solvents (DESs) and dilutions thereof (mainly in H2O but also in many other non-aqueous solvents and co-solvent mixtures) have recently attracted great attention. It is well known that DES dilutions exhibit deviations from ideality. Interestingly, the treatment of DES as a mixture of two components or a pseudo-component is by no means trivial when determining deviations in density and, mainly, in viscosity. Herein, we studied aqueous dilutions of one of the most widely studied DES, this is, that composed of choline chloride and urea in a 1:2 molar ratio (e.g., ChCl2U). Using density and viscosity data reported in previous works, we calculated the excess molar volumes (VE) and excess viscosities (ln ηE) considering ChCl2U as either a mixture of two components or a pseudo-component, that is, taking the DES molecular weight as MChCl2U = fChClMChCl + fUMU = 86.58 g mol-1 (with fChCl = 1/3 and fU = 2/3) or as M* ChCl2U = MChCl + 2 MU = 259.74 g mol-1. We found that neither the sign of VE and VE* nor their evolution with temperature was influenced by the use of either MChCl2U or M* ChCl2U, and only the absolute magnitude of the deviation and the DES content (in wt. %) at which the minimum appears exhibited some differences. However, ln ηE and ln ηE* exhibited opposite signs, negative and positive, respectively. The odd achievement of negative ln ηE in aqueous dilutions of ChCl2U characterized by the formation of HB networks suggest the treatment of ChCl2U as a pseudo-component as more appropriate. Moreover, the role played by the presence of U in the evolution of ln ηE* with temperature was also discussed.

20.
Talanta ; 232: 122430, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34074416

RESUMO

A fast and simple strategy based on the microwave technique for the preparation of magnetic molecularly imprinted polymers (MMIPs) is proposed for the selective determination of sulfamethoxazole (SMX). The MMIPs were synthesized at 70 °C in 20 min, being much faster than the conventional techniques. A computational approach based on density functional theory was used to design the MMIP and compare the two most used monomers in MIPs, including methacrylic acid (MAA) and acrylamide (AM). Then, two different MMIPs were prepared using AM and MAA as monomers. The resultant materials were characterized with X-ray diffraction, thermogravimetric analysis, scanning/transmission electron microscopy, and Fourier-transform infrared spectroscopy. Besides, the adsorption characterizations suggested that the adsorption of SMX followed the pseudo-second-order model in the kinetic study and the Sips model in the isotherm study. The experimental results corroborated the computational approach. Furthermore, Both MMIPs demonstrated good selectivity. The MMIP-AM and MMIP-MAA were applied as adsorbents in magnetic dispersive solid-phase extraction combined with UV-visible spectroscopy to quantify SMX. The obtained limits of detection and quantification were lower than 0.59 and 1.77 µM, respectively for both MMIPs. The sensitivity of both MMIPs was in the range of 0.021-0.023 (SI). Our findings revealed that there is no significant difference in the analytical parameters between MMIP-AM and MMIP-MAA. However, the application of both MMIPs in a real sample (tap water) showed that the recovery values of SMX obtained with MMIP-AM (68-70%) were lower than that with MMIP-MAA (80-90%) suggesting that MMIP-MAA is more appropriate for SMX determination.

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