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1.
Cancer Immunol Immunother ; 73(1): 5, 2024 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-38180524

RESUMO

Cancer immunotherapies strive to overcome tumor-induced immune suppression and activate antitumor immune responses. Although cytotoxic T lymphocytes (CTLs) play a pivotal role in this process, natural killer (NK) cells have also demonstrated remarkable tumor-killing abilities, given their ability to discriminate tumor cells from normal cells and mediate specific antitumoral cytotoxicity. NK cells activation depends on a balance between activation and inhibition signals from several ligands/receptors. Among them, MICA/NKG2D axis is a master regulator of NK activation. MHC class I chain-related polypeptide A (MICA) expression is upregulated by many tumor cell lines and primary tumors and serves as a ligand for the activating NK group 2D (NKG2D) receptor on NK cells and subpopulations of T cells. However, cancer cells can cleave MICA, making it soluble and de-targeting tumor cells from NK cells, leading to tumor immune escape.In this study, we present ICOVIR15KK-MICAMut, an oncolytic adenovirus (OAdv) armed with a transgene encoding a non-cleavable MICA to promote NK-mediated cell-killing capacity and activate the immune response against cancer cells. We first demonstrated the correct MICA overexpression from infected cells. Moreover, our MICA-expressing OAdv promotes higher NK activation and killing capacity than the non-armed virus in vitro. In addition, the armed virus also demonstrated significant antitumor activity in immunodeficient mice in the presence of human PBMCs, indicating the activation of human NK cells. Finally, OAdv-MICA overexpression in immunocompetent tumor-bearing mice elicits tumor-specific immune response resulting in a greater tumor growth control.In summary, this study highlights the significance of NK cells in cancer immunotherapy and presents an innovative approach using a modified oncolytic virus to enhance NK cell activation and antitumor immune response. These findings suggest promising potential for future research and clinical applications.


Assuntos
Adenoviridae , Subfamília K de Receptores Semelhantes a Lectina de Células NK , Humanos , Animais , Camundongos , Adenoviridae/genética , Subfamília K de Receptores Semelhantes a Lectina de Células NK/genética , Ativação Linfocitária , Genes MHC Classe I , Evasão Tumoral
2.
Analyst ; 149(8): 2483, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38497325

RESUMO

Correction for 'Inkjet-printed O2 gas sensors in intelligent packaging' by M. D. Fernández-Ramos et al., Analyst, 2021, 146, 3177-3184, https://doi.org/10.1039/D1AN00295C.

3.
Analyst ; 149(8): 2480, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38498079

RESUMO

Correction for 'An optical sensor for the sensitive determination of formaldehyde gas based on chromotropic acid and 4-aminoazobenzene immobilized in a hydrophilic membrane' by M. D. Fernández-Ramos et al., Analyst, 2023, 148, 4533-4538, https://doi.org/10.1039/D3AN01056B.

4.
Analyst ; 148(18): 4533-4538, 2023 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-37585267

RESUMO

Formaldehyde is a common contaminant in occupational and environmental atmospheres, prolonged exposure leads to health risks, and its determination is necessary to protect health. There is a great demand for portable, rapid, and sensitive methods that can be used in resource-limited settings. In this respect, a colorimetric sensor has been developed based on the colour change from pink to purple of co-immobilized chromotropic acid and 4-aminoazobenzene in hydroxypropyl methylcellulose when it is exposed to different concentrations of formaldehyde. The concentration of formaldehyde in the gas phase was quantified by measuring the change of the appropriate colour coordinates in response to the concentration of formaldehyde. A calibration curve was obtained for formaldehyde, with a useful concentration range from 0.08 to 0.6 ppmv. The detection limit was 0.016 ppmv, which is lower than the maximum exposure concentrations recommended by both the World Health Organization (WHO) and the Occupational Safety and Health Administration (OSHA). The optical sensor was found to have good reproducibility, with a relative standard deviation of 2.3 and 1.7% at 0.08 and 0.25 ppmv, respectively. The sensor can operate at room temperature and environmental humidity, 25 °C, and 50% RH, respectively. In addition, a study of interferents (acetaldehyde, toluene, methanol, ethyl acetate, acetone, acetic acid, carbon dioxide and ammonia) showed high selectivity for formaldehyde, which indicates that this membrane is a simple, fast, and economical alternative for quantifying the concentration of formaldehyde in different environments.


Assuntos
Colorimetria , Formaldeído , Reprodutibilidade dos Testes , Colorimetria/métodos , Naftalenossulfonatos
5.
Mikrochim Acta ; 190(4): 160, 2023 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-36973585

RESUMO

Two colorimetric nanostructured sensor phases (Color-NSPs) for the determination of low concentrations of acid vapors in the atmosphere of paper storage rooms have been designed and characterized. The acid vapor determination is based on the color change that occurs in polyaniline (PANI) in the presence of acids when it goes from its emeraldine base form (blue) to its emeraldine salt form (green). To synthesize the Color-NSPs, two methods have been used, a one-step method performed by grafting polyaniline onto a cellulose membrane (Cellu-PANI) and a two-step method in which in the first step, polyaniline is grafted onto the surface of polymeric nanoparticles (NPs-PANI), and in a second step, NPs-PANI are immobilized into the pores of a nylon membrane (Nylon-NPs PANI). The response of the sensors versus acid vapor was measured by color coordinates with a photographic camera. A linear response range from 1 ppmv to 7 ppmv was found for both sensors, and the detection limits were 0.95 ppmv (1.2 % RSD) and 0.40 ppmv (0.8 % RSD) for Cellu-PANI and Nylon-NPs PANI, respectively. In addition, both sensors showed complete reversibility and a short exposition time (5 min). The potential applicability of the Color-NSPs in the control of the exposure of paper heritage collections to outdoor- and indoor-generated gaseous pollutants was demonstrated by determining acid vapors in museums. The method was validated with an external reference method; the paired test was applied, and p-values greater than 5% were obtained, indicating an excellent correlation and showing that the Color-NSPs reported are simple, fast, and an economical alternative to control and protect cultural heritage materials in indoor environments.

6.
Analyst ; 146(10): 3177-3184, 2021 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-33999075

RESUMO

An inkjet printed membrane is presented as a colorimetric sensor for oxygen for use in smart packaging, in order to quickly inform the consumer about possible degradation reactions in modified atmosphere products (MAP). The colorimetric sensor is based on the redox dye, toluidine blue (TB), a sacrificial electron donor, glycerol, and, hydroxypropyl methylcellulose, as the hydrophilic polymeric matrix. The UVC-wavelength activated TB is photoreduced by SnO2 nanoparticle ink. This colorimetric oxygen indicator stays colourless upon exposure in nitrogen atmosphere to 7 min UVC light (6 W·cm-2). The photoreduced TB to leuco TB recovers its original colour upon exposure to oxygen for 55 min under ambient conditions (∼21 °C, ∼55%RH, 21% O2). The characteristics of the sensor have been evaluated, including its functionality through the colorimetric response to different oxygen concentrations as well as the influence of experimental variables such as humidity and temperature using a digital camera as the detector. The results obtained show that: (1) the colorimetric sensor remains stable in the absence of oxygen; (2) relative humidity greater than 60% significantly affects the reoxidation process; and (3) the temperature has a significant influence on the colour recovery, although the stability increases considerably when the sensor is kept refrigerated at 4 °C. A real application to packaged ham was performed, demonstrating that the printed colorimetric sensor is stable for at least 48 hours once activated and when the container deteriorates upon the entrance of oxygen, the sensor returns to its original blue colour, demonstrating its utility as a UVC-activated colorimetric oxygen sensor.

7.
Med Oral Patol Oral Cir Bucal ; 25(3): e359-e363, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32040461

RESUMO

BACKGROUND: Although the third molar is the tooth with the greatest anatomical and developmental variability, some authors consider it important to estimate whether a subject is of legal age or not. The Demirjian's technique is the most widely used tool to estimate dental age and was therefore used in our study to assess possible correlation between the age of majority and the maturational degree of the lower third molars, evaluated through radiographic images. MATERIAL AND METHODS: This observational transversal study was conducted on 180 panoramic radiographs from consecutive patients. The degree of maturation of the lower third molar was independently classified by two observers, according to the Demirjian´s maturational stage method. RESULTS: A total of 180 patients - 65 men (36.12%) and 115 women (63.88%) - were included (mean age 21.6 years; standard deviation 5.2). The age range of our subjects corresponded to maturational stages D to H in the Demirjian's classification. A logistic regression analysis showed that subjects classified into the highest maturational stage H had a significantly higher probability of being considered of legal age by both observers, as compared with subjects in the lowest stage D. Inter-observer agreement was very high. Gender predictive capacity was not observed. CONCLUSIONS: Our results showed that subjects with the lower third molars in the highest maturational stage could be estimated to be older than 18 years and therefore considered of legal age, a finding also reported by other authorsThe Demirjian´s tooth maturational stage method, applied to the lower third molars, can be reliably used to estimate whether an individual is of legal age (18 years or older). High concordance between different observers using this method can be expected.


Assuntos
Determinação da Idade pelos Dentes , Dente Serotino , Adulto , Feminino , Humanos , Masculino , Radiografia Panorâmica , Adulto Jovem
8.
Analyst ; 144(12): 3870-3877, 2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31111127

RESUMO

Two simple boron-dipyrromethene-type fluorophore (azaBODIPYs) dyes are synthesized and tested for the determination of CO2 gas by an inner filter process. The indicators are noncovalently entrapped in suitable polymers according to their polarity, featuring absorption maxima at 620 nm and fluorescent emission maxima in the range 675-720 nm. Molar absorptivity and fluorescence quantum yield data were determined for these two synthesized azaBODIPYs. These indicators have high molar absorption coefficients of 7.1 × 104 and 2.1 × 104 M-1 cm-1 and quantum yields of 21 and 9%. The pKa values of the indicators are determined from absorbance and fluorescence measurements with values of 7.9 and 8.5, depending on the positioning of the substitution pattern of the electron-donating functionalities. The two azaBODIPYs present excellent photostability, making them suitable for long duration measurements. These azaBODIPY dyes act as fluorescent pH indicators in a polymeric sensing membrane along with microcrystalline powder of chromium-doped gadolinium aluminium borate as the luminophore, a transfer phase agent (tetraoctyl or tetramethyl ammonium hydroxide) and a plasticizer or surfactant to improve membrane permeability to gaseous CO2. The response time ranges from 42 to 60 s and recovery time from 103 to 120 s, with a detection limit of 0.04 and 0.57% CO2. The store time of the sensing membranes is longer than 570 days in the best case, and it does not need to be kept in any special atmosphere other than darkness.

9.
Anal Bioanal Chem ; 410(23): 5931-5939, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29974155

RESUMO

This work presents a study on the influence of eight different ionic liquids (ILs) in the composition of dry membranes used for gaseous CO2 optical sensing. The presence of CO2 causes a displacement of a colorimetric pH indicator toward its acid form that increases the emission intensity of the luminophore by an inner filter process. The influence of ILs in the membrane on the stability and dynamic behavior-usually the main drawbacks of these sensors-of the membranes is studied. The characterization of the different membranes prepared was carried out and the discussion of the results is presented. In all cases, the response and recovery times improved considerably, with the best case being response times of only 10 s and recovery times of 48 s, compared to response and recovery times of 41 and 100 s, respectively, for membranes without IL. The useful life of the detection membranes is also considerably longer than that of membranes that do not include IL, at least 292 days in the best case. The sensing membrane without luminophore and only containing the pH indicator is proposed for the color-based measurement of CO2 using a digital camera for possible use in food-packaging technology. Graphical abstract ᅟ.

10.
Rev Enferm ; 40(4): 48-54, 2017 Apr.
Artigo em Espanhol | MEDLINE | ID: mdl-30277709

RESUMO

Introduction: Aiming at detecting possible causes for the lack of male nursing professionals, Bartfay et al. developed a questionnaire named Attitudes Towards Men in Nursing Scale (ATMINS), which they tested a university in Ontario, Canada. Objective: Achieve a cross-cultural adaptation and validation of the Attitudes Towards Men in Nursing Scale (ATMINS), in order to evaluate if results achieved using a Spanish sample are comparable with the Canadian study's results. Participantsm, Materials, and Method: Participants were recruited in universities of Alicante and Donostia (Basque Country). To assure voluntary participation in the study, all candidates were informed about the objective of the study and giving enough time to read the questionnaire. The questionnaire used was the Attitudes Toward Men in Nursing Scale (ATMINS), translated to Spanish. The Spanish version of the ARMINS scale was handed over to a total of 142 students from the Nursing Universities of Alicante and Donostia. Time needed to fill the questionnaires didn't exceed 5 minutes in any case, and no difficulty was observed during implementation. After testing the scale, an internal consistency analysis was performed using Cronbach's Alpha with correction by eliminating items. Validation of construct was done via Exploratory Factorial analysis with Varimax rotation. Results: The results show a reliability which does not reach a moderate degree. Eliminating item 6 in all subsamples, as well as the total sample suppressing any of the other 5 items, increases internal consistency. The exploratory factorial analysis supports a bi-factorial structure of the questionnaire with very high saturation on each factor and a negative charge inside factor 2 for item 6. The negative charge of item 6 keeps the saturation (0.717) after its inversion. By performing an internal consistency analysis taking only into account items of factor 1, the scale's consistency improves with results close to 0.70. Conclusion: The revised scale is a tool which enables easy and fast application. It is valid for the Spanish sample and provides an acceptable internal consistency. The results obtained in both universities in Spain and in Canada are comparable.


Assuntos
Atitude , Enfermeiros , Autorrelato , Canadá , Características Culturais , Feminilidade , Humanos , Masculinidade , Fatores Sexuais , Espanha
11.
Clin Genet ; 86(1): 91-5, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23837941

RESUMO

The term cystic fibrosis (CF)-like disease is used to describe patients with a borderline sweat test and suggestive CF clinical features but without two CFTR(cystic fibrosis transmembrane conductance regulator) mutations. We have performed the extensive molecular analysis of four candidate genes (SCNN1A, SCNN1B, SCNN1G and SERPINA1) in a cohort of 10 uncharacterized patients with CF and CF-like disease. We have used whole-exome sequencing to characterize mutations in the CFTR gene and these four candidate genes. CFTR molecular analysis allowed a complete characterization of three of four CF patients. Candidate variants in SCNN1A, SCNN1B, SCNN1G and SERPINA1 in six patients with CF-like phenotypes were confirmed by Sanger sequencing and were further supported by in silico predictive analysis, pedigree studies, sweat test in other family members, and analysis in CF patients and healthy subjects. Our results suggest that CF-like disease probably results from complex genotypes in several genes in an oligogenic form, with rare variants interacting with environmental factors.


Assuntos
Regulador de Condutância Transmembrana em Fibrose Cística/genética , Fibrose Cística/genética , Canais Epiteliais de Sódio/genética , Fenótipo , alfa 1-Antitripsina/genética , Adolescente , Adulto , Sequência de Bases , Criança , Fibrose Cística/patologia , Exoma/genética , Feminino , Humanos , Masculino , Dados de Sequência Molecular , Herança Multifatorial/genética , Linhagem , Análise de Sequência de DNA
12.
J Med Genet ; 50(7): 455-62, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23687349

RESUMO

BACKGROUND: Here we have developed a novel and much more efficient strategy for the complete molecular characterisation of the cystic fibrosis (CF) transmembrane regulator (CFTR) gene, based on multiplexed targeted resequencing. We have tested this approach in a cohort of 92 samples with previously characterised CFTR mutations and polymorphisms. METHODS: After enrichment of the pooled barcoded DNA libraries with a custom NimbleGen SeqCap EZ Choice array (Roche) and sequencing with a HiSeq2000 (Illumina) sequencer, we applied several bioinformatics tools to call mutations and polymorphisms in CFTR. RESULTS: The combination of several bioinformatics tools allowed us to detect all known pathogenic variants (point mutations, short insertions/deletions, and large genomic rearrangements) and polymorphisms (including the poly-T and poly-thymidine-guanine polymorphic tracts) in the 92 samples. In addition, we report the precise characterisation of the breakpoints of seven genomic rearrangements in CFTR, including those of a novel deletion of exon 22 and a complex 85 kb inversion which includes two large deletions affecting exons 4-8 and 12-21, respectively. CONCLUSIONS: This work is a proof-of-principle that targeted resequencing is an accurate and cost-effective approach for the genetic testing of CF and CFTR-related disorders (ie, male infertility) amenable to the routine clinical practice, and ready to substitute classical molecular methods in medical genetics.


Assuntos
Regulador de Condutância Transmembrana em Fibrose Cística/genética , Fibrose Cística/diagnóstico , Fibrose Cística/genética , Sequência de Bases , Bronquiectasia/genética , Estudos de Coortes , Éxons , Testes Genéticos , Humanos , Infertilidade Masculina/genética , Masculino , Dados de Sequência Molecular , Polimorfismo Genético , Ducto Deferente/anormalidades
13.
Radiologia ; 55(3): 247-52, 2013.
Artigo em Espanhol | MEDLINE | ID: mdl-22033035

RESUMO

INTRODUCTION: We aimed to evaluate the usefulness of magnetic resonance imaging (MRI) in the diagnosis of occult fractures of the scaphoid and to determine the advantages and cost in comparison with the traditional follow-up protocol. MATERIAL AND METHOD: The traditional approach at our center consisted of immobilization and periodic clinical and radiological follow-up (plain-film X-rays and computed tomography in the final phase of the process). The new protocol called for a limited MRI study consisting of coronal T1- and T2-weighted fat suppression sequences if the findings at plain-film X-rays continued to be negative at the first follow-up examination with the traumatologist (10 days after trauma). We evaluated the MRI findings, the time the patient was immobilized, the cost of each protocol, and the dose of radiation received. RESULTS: We included 33 cases of patients with clinically suspected fractures of the scaphoid and negative findings on plain-film X-rays. In 13 patients, the MRI findings were negative. In 12 patients, the MRI findings confirmed the diagnosis of a fracture of the scaphoid, which was associated with other pathology in 6 cases. In 8 patients, another pathological process was diagnosed. The cost of the new protocol was €131.06 per patient; the cost of the traditional protocol was €114.41 or €151.06 per patient, depending on the follow-up studies required. The new protocol reduced the dose of radiation by eliminating successive radiologic studies. CONCLUSIONS: The new protocol improved the management of these patients, reducing the time of immobilization, improving joint rigidity, and reducing the time off work. The limited MRI study makes it possible to diagnose other radiologically occult lesions. The cost of the new protocol is similar to that of the traditional protocol and even lower in some cases. The new protocol results in a reduction in the dose of radiation.


Assuntos
Fraturas Fechadas/diagnóstico , Imageamento por Ressonância Magnética , Osso Escafoide/lesões , Adolescente , Adulto , Idoso , Diagnóstico Precoce , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
14.
Talanta ; 254: 124189, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36525868

RESUMO

A microfluidic biosensor paper-based analytical device, or µPAD, was developed as a point-of-care assay platform for the simultaneous determination of three clinically important markers: uric acid, urea, and triglycerides. To achieve a simultaneous determination, thermosensitive valves based on N-isopropylacrylamide polymers controlled the flow of fluid in the µPAD. The evaluation of the analytical characteristics of the µPAD was done using a photographic camera at room temperature. The detection limits were 4.5·10-5, 2.5·10-3, and 1.5·10-3 mg mL-1, for uric acid, urea, and triglycerides, respectively, and the precision expressed as relative standard deviation (% RSD) 3.2, 1.2, and 1.6%. The obtained µPAD devices were validated with real human plasma samples, demonstrating high accuracy and precision. Multiple analyte point-of-care tests such as those developed here have excellent characteristics, being easy to manufacture, cost-effective, easy to use, and highly sensitive.


Assuntos
Técnicas Analíticas Microfluídicas , Ácido Úrico , Humanos , Sistemas Automatizados de Assistência Junto ao Leito , Microfluídica , Triglicerídeos , Ureia , Papel
15.
Anal Bioanal Chem ; 404(10): 2851-8, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22895739

RESUMO

A portable instrument for oxygen determination, based on the quenching of phosphorescent octaethylporphyrin by gaseous O(2), has been developed using the fluorimetric paired emitter-detector diode technique (FPEDD). The instrument configuration consists of two light-emitting diodes (LEDs) facing each other, with an interchangeable support containing a phosphorescent membrane in between, in which one of the LEDs is used as the light source (emitter LED) and the other, working in reverse bias mode, as the light detector. The feasibility of using a LED as a luminescence detector is studied. Its small size enables integration of the instrument into a portable measurement system. A systematic study of the system capabilities as a portable instrument was performed to optimize range, sensitivity, short term and long term stability, dynamic behaviour, effect of temperature and humidity, and temporal drift.

16.
Nat Commun ; 13(1): 72, 2022 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-35013232

RESUMO

The use of facemasks by the general population is recommended worldwide to prevent the spread of SARS-CoV-2. Despite the evidence in favour of facemasks to reduce community transmission, there is also agreement on the potential adverse effects of their prolonged usage, mainly caused by CO2 rebreathing. Herein we report the development of a sensing platform for gaseous CO2 real-time determination inside FFP2 facemasks. The system consists of an opto-chemical sensor combined with a flexible, battery-less, near-field-enabled tag with resolution and limit of detection of 103 and 140 ppm respectively, and sensor lifetime of 8 h, which is comparable with recommended FFP2 facemask usage times. We include a custom smartphone application for wireless powering, data processing, alert management, results displaying and sharing. Through performance tests during daily activity and exercise monitoring, we demonstrate its utility for non-invasive, wearable health assessment and its potential applicability for preclinical research and diagnostics.


Assuntos
Técnicas Biossensoriais/instrumentação , COVID-19/prevenção & controle , Dióxido de Carbono/análise , Máscaras , Equipamento de Proteção Individual , Dispositivos Eletrônicos Vestíveis , Técnicas Biossensoriais/métodos , COVID-19/transmissão , COVID-19/virologia , Desenho de Equipamento , Humanos , Reprodutibilidade dos Testes , SARS-CoV-2/fisiologia
17.
Anal Bioanal Chem ; 401(9): 2881-9, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21898154

RESUMO

An approach based on IUPAC methodology to estimate the limit of detection of bulk optode-based analytical methods for anions has been developed. The traditional IUPAC methodology for calculating the detection limit was modified to be adapted to particular cases where the calibration curves have a sigmoidal profile. Starting from the different full theoretical models for every co-extraction mechanism of the analyte in the membrane in bulk optodes, several particular simplified models at low analyte concentration were obtained and validated. The slope of the calibration curve at low analyte concentration was calculated from the first derivative of the simplified equation and, subsequently, the detection limit was estimated. This fitted-for-purpose estimation strategy was applied to anion quantification for in-house bulk optode-based analytical methods, and the estimated limits of detection were compared with those obtained by applying classical geometrical methodology. This way of establishing the detection limit yields values that maintain their true statistical and probabilistic aspects. It can be easily applied to any analytical system which yields non-linear calibration curves at low analyte concentration.


Assuntos
Ânions/análise , Técnicas de Química Analítica/métodos , Guias de Prática Clínica como Assunto/normas , Calibragem , Técnicas de Química Analítica/normas , Técnicas de Química Analítica/estatística & dados numéricos , Humanos , Cinética , Limite de Detecção , Modelos Estatísticos , Dispositivos Ópticos , Análise de Regressão
18.
Talanta ; 218: 121108, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32797872

RESUMO

This work presents a new optical microfluidic paper biosensor for the detection of organophosphate pesticides and carbamate pesticides. The assay strip is composed of a paper support (1 × 17.6 mm) onto which acetylcholine esterase (AChE) and acetylcholine chloride (AChCl) are deposited, in such a way that there is a small hole between them that ensures that they only come into contact in the reaction zone when they are carried by a solution of the sample by lateral flow to the reaction zone containing bromocresol purple (BCP) as the pH indicator, immobilized by sol-gel. The sensor operates at room temperature and the rate of the inhibited reaction serves as an analytical signal, which is measured using a camera by quantifying the appropriate colour coordinate. Calibration curves were obtained for chlorpyrifos and carbaryl, with a useful concentration range from 0.24 to 20 µg L-1 for carbaryl and from 2.00 to 45 µg L-1 for chlorpyrifos. The detection limits were 0.24 and 2.00 µg L-1, respectively, and with reproducibility around 4.2-5.5%. The method was applied to the determination of pesticides in different water samples, with no sample preparation.


Assuntos
Técnicas Biossensoriais , Clorpirifos , Praguicidas , Carbaril , Microfluídica , Reprodutibilidade dos Testes
19.
Talanta ; 208: 120387, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31816777

RESUMO

A portable device based on a colorimetric sensor to determine the atmospheric level of CO2 gas is presented in this work. The system is based on a low-cost, low-power System on a Chip (SoC) microcontroller with integrated Wi-Fi. A user-friendly application was developed to monitor and log the CO2 measurements when the system is connected to a Wi-Fi network. The sensing membrane is directly deposited on the surface of the colour detector, thus reducing the complexity of the system. This sensing membrane is formed by a pH indicator α-naphtholphthalein, tetramethylammonium hydroxide pentahydrate, 1-ethyl-3-methylimidazolium tetrafluoroborate, Tween 20 and hydroxypropyl methylcellulose as the hydrophilic polymer. The system has been fully characterized, obtaining response and recovery times of 1.3 and 2.5 s, respectively, a limit of detection of 51 ppm, and an average resolution of 6.3 ppm. This portable device was applied for the in-situ determination of CO2 gas in the atmosphere inside classrooms in several secondary schools. The measurements were taken during complete workdays and the results were statistically compared with the same measurements taken using a commercially available non-dispersive infra-red (NDIR) device. No significant statistical differences were found between the results obtained using both devices. A complete statistical treatment of the measurements made with the proposed portable device was carried out. The obtained results show that the concentration of CO2 gas in some schools was higher than the desired concentration, with regard to influencing the student's health, safety, productivity and comfort. This demonstrates the need to control this parameter to ensure appropriate indoor environmental quality (IEQ).

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