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1.
Spectrochim Acta A Mol Biomol Spectrosc ; 284: 121784, 2023 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-36054954

RESUMO

Spectrophotometry is an economic and rapid method for detecting oxalic acid (OA), while the reported methods have some drawbacks, such as narrow linear range, long response time, delicate operation and required expensive reagents. Herein, we found that the as-synthesized Fe(III)-sulfosalicylate (FeSSA) could be used as an efficient colorimetric chemosensor to detect OA, and the established FeSSA-based fading spectrophotometry showed prominent advantages over the existing ones in detecting OA. The as-established method has wider linear range of 0.80-160 mg/L with regression coefficient ≥ 0.999, while the widest linear range is just 2.7-54 mg/L among the reported ones. Moreover, the method has low limit of detection (0.74 mg/L), extremely fast response (several seconds), satisfactory selectivity, high accuracy and precision. Most importantly, its reliability was further verified by employing it to determine OA concentration during the degradation process of organic pollutants. The measured OA concentration at any time interval was perfectly consistent with those determined by the well-recognized high performance liquid chromatography (HPLC). These confirmed that the FeSSA-based fading spectrophotometry is an efficient, simple, fast, accurate and economic method to determine OA in a wide concentration range.


Assuntos
Poluentes Ambientais , Ácido Oxálico , Colorimetria/métodos , Poluentes Ambientais/análise , Compostos Férricos , Ácido Oxálico/análise , Ácido Oxálico/química , Reprodutibilidade dos Testes , Espectrofotometria/métodos
2.
Spectrochim Acta A Mol Biomol Spectrosc ; 285: 121853, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36115307

RESUMO

In this paper, a spectrophotometric method for nicotine detection based on plasmonic nanoparticles (AuNPs and AgNPs) is proposed. Due to their specific properties, plasmonic nanoparticles have become interesting to use in the development of sensitive analytical methods. The localized surface plasmon resonance (LSPR) absorption bands for AgNPs and AuNPs with a wavelength at 395.5 nm (A395.5) and 543.5 (A543.5) nm, respectively, are used for the detection. Experimental variables such as solvent type and pH were optimized so as to determine the optimum working conditions. The analytical calibration curve for both AgNPs and AuNPs based on spectrophotometric methods was prepared with nicotine concentrations range from 0.10 to 5.00 µM (R2 = 0.9903) and 0.001-0.300 µM (R2 = 0.9960), respectively. The detection limits were found to be 0.001 µM for AuNPs based method and 0.09 µM for AgNPs based method. The proposed nanoparticle-based spectrophotometric methods showed a good stability, selectivity and low detection limit.


Assuntos
Ouro , Nanopartículas Metálicas , Ouro/química , Nanopartículas Metálicas/química , Nicotina , Ressonância de Plasmônio de Superfície , Espectrofotometria
3.
Spectrochim Acta A Mol Biomol Spectrosc ; 285: 121911, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36174404

RESUMO

Molnupiravir is an oral antiviral drug developed to provide significant benefit in reducing hospitalizations or deaths in mild COVID-19. Integrated green computational spectrophotometric method was developed for the determination of molnupiravir. Theoretical calculations were performed to predict the best coupling agent for efficient diazo coupling of molnupiravir. The binding energy between molnupiravir and various phenolic coupling agents, α-naphthol, ß-naphthol, 8-hydroxyquinoline, resorcinol, and phloroglucinol, was measured using Gaussian 03 software based on the density functional theory method and the basis set B3LYP/6-31G(d). The results showed that the interaction between molnupiravir and 8-hydroxyquinoline was higher than that of other phenolic coupling agents. The method described was based on the formation of a red colored chromogen by the diazo coupling of molnupiravir with sodium nitrite in acidic medium to form a diazonium ion coupled with 8-hydroxyquinoline. The absorption spectra showed maximum sharp peaks at 515 nm. The reaction conditions were optimized. Beer's law was followed over the concentration range of 1-12 µg/ml molnupiravir. Job's continuous variation method was developed and the stoichiometric ratio of molnupiravir to 8-hydroxyquinoline was determined to be 1:1. The described method was successfully applied to the determination of molnupiravir in pure form and in pharmaceutical dosage form. The results showed that the proposed method has minimal environmental impact compared to previous HPLC method.


Assuntos
COVID-19 , Humanos , Espectrofotometria/métodos , Oxiquinolina , Preparações Farmacêuticas
4.
Spectrochim Acta A Mol Biomol Spectrosc ; 285: 121918, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36179569

RESUMO

An easy and reliable method is optimized for extractive spectrophotometric assessment of platinum(IV) with 4-(4'-nitrobenzylideneimino)-3-methyl-5-mercapto-1,2,4-triazole as an extractant. The basis of this method is the formation of red platinum(IV) complex with the above reagent in acetate buffer medium (pH 5.0) and extraction in chloroform. Good linearity with regression equation as y = 1.011 × 104 ×  + 0.002 having correlation coefficient (R2) of 0.998 over concentration up to 17.5 µg mL-1 of platinum(IV) was achieved with apparent molar absorptivity of 1.011 × 104 L mol-1 cm-1. The limit of detection (0.22 µg mL-1), limit of quantification (0.73 µg mL-1) and Sandell's sensitivity (0.0193 µg cm-2) were also estimated. The interference of various cations was removed by using proper masking agents and consequently by using EDTA and citrate to mask certain transition metals, the method becomes highly specific for platinum(IV), including the effects of platinum group metals. The method is effectively used for determination of platinum(IV) from environmental and real samples such as alloys, catalysts, thermocouple wire and pharmaceutical sample.


Assuntos
Cisplatino , Platina , Espectrofotometria/métodos , Ligas , Indicadores e Reagentes
5.
J Sci Food Agric ; 103(1): 7-25, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-35821577

RESUMO

White wine phenolic analyses are less common in the literature than analyses of red wine phenolics. Analytical techniques for white wine phenolic analyses using spectrophotometric, chromatographic, spectroscopic, and electrochemical methods are reported. The interest of research in this area combined with the advances in technology aimed at the winemaking industry are promoting the establishment of novel approaches for identifying, quantifying, and classifying phenolic compounds in white wine. This review article provides an overview of the current research into white wine phenolics through a critical discussion of the analytical methods employed. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Assuntos
Vitis , Vinho , Vinho/análise , Fenóis/análise , Espectrofotometria , Vitis/química
6.
Methods Mol Biol ; 2598: 115-121, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36355288

RESUMO

The 1,9-dimethylmethylene blue (DMMB) assay enables the detection of sulfated glycosaminoglycans (sGAGs). This assay can be used to quickly quantify the sGAG content in a large number of samples using spectrophotometry. While this widespread assay appears straightforward, there are certain pitfalls that need to be considered.


Assuntos
Glicosaminoglicanos , Azul de Metileno , Espectrofotometria
7.
Food Chem ; 402: 134457, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36303382

RESUMO

A simple, green and equitable procedure for total biogenic amines (BAs) content determination was developed. The scientific novelty lies in the use of commercially available S0378 dye, the reaction of which with BAs results in a colour change of the solution. Sample preparation and analysis were simplified to make the method suitable for routine analyses even in resource-scarce settings. The optimization of the method was carried out using a Box-Behnken response surface design. The developed method has satisfactory figures of merit for putrescine equivalent determination with R2 in the range of 0.9906-0.9933 and recovery between 99.7 and 101.2%. The method's greenness was assessed using AGREEprep. Finally, wine samples were analysed to demonstrate the applicability of the developed method.


Assuntos
Vinho , Vinho/análise , Aminas Biogênicas/análise , Espectrofotometria , Cromatografia Líquida de Alta Pressão/métodos
8.
Food Chem ; 399: 133929, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36055067

RESUMO

The main purpose of this research article is to develop a vortex-assisted switchable hydrophilicity solvent liquid phase microextraction (VA-SHS-LPME) for the selective and efficient extraction of trace vanillin in food samples. Four switchable hydrophilicity solvents (SHSs) were prepared and tested for the extraction of vanillin. The obtained extract phase after phase separation was analyzed by UV-vis spectrophotometry. The extraction parameters including pH, vortex time, NaOH volume, and SHS volume were optimized using central composite design based on response surface methodology. Under optimized conditions, the linear range (0.2-400 ng mL-1 with r2 = 0.9985), limit of detection (0.06 ng mL-1), limit of quantitation (2.0 ng mL-1), extraction recovery (97 ± 4 %) and enhancement factor (220) were obtained. Also, relative standard deviations were less than 2.1 % indicating good precision. The VA-SHS-LPME procedure showed some advantages including good extraction, low consumption of chemical and low matrix effect. Finally, the VA-SHS-LPME procedure was applied for the determination of vanillin in food samples, and acceptable recoveries (91 ± 3-99 ± 3 %) were obtained.


Assuntos
Microextração em Fase Líquida , Benzaldeídos , Interações Hidrofóbicas e Hidrofílicas , Limite de Detecção , Microextração em Fase Líquida/métodos , Solventes , Espectrofotometria
9.
PLoS One ; 17(10): e0276040, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36228033

RESUMO

The spectrophotometer has been used for decades to measure the density of bacterial populations as the turbidity expressed as optical density-OD. However, the OD alone is an unreliable metric and is only proportionately accurate to cell titers to about an OD of 0.1. The relationship between OD and cell titer depends on the configuration of the spectrophotometer, the length of the light path through the culture, the size of the bacterial cells, and the cell culture density. We demonstrate the importance of plate reader calibration to identify the exact relationship between OD and cells/mL. We use four bacterial genera and two sizes of micro-titer plates (96-well and 384-well) to show that the cell/ml per unit OD depends heavily on the bacterial cell size and plate size. We applied our calibration curve to real growth curve data and conclude the cells/mL-rather than OD-is a metric that can be used to directly compare results across experiments, labs, instruments, and species.


Assuntos
Bactérias , Espectrofotometria/métodos
10.
Acta Odontol Latinoam ; 35(2): 98-104, 2022 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-36260940

RESUMO

The aim of this study was to evaluate tooth color in dental students at the University of Buenos Aires, Argentina. The participants were 184 students (157 women and 27 men) aged 21 to 33 years, mean age 24.45 (SD 2.79) years, who were in the fourth year of their dental degree. They agreed to participate through an informed consent. Exclusion criteria were: having undergone a bleaching treatment within the previous six months, presence of total or partial peripheral restoration, pigmentations, fracture, carious and non-carious lesions or absence of the right upper central incisor (1.1). A dental prophylaxis procedure was performed on the buccal surface of each 1.1 tooth with a prophylaxis brush (TDV) mounted on a low-speed rotary instrument Kavo 2068 CHC (Germany) micromotor and a Kavo LUX K201(Germany) contra-angle. Shade was measured in the middle third of each 1.1 tooth, by the same observer, using a VITA Easyshade V spectrophotometer (Zahnfabrikn Bad Säckingen, Germany), which was calibrated before each determination according to manufacturer's instructions, in the same dental unit (Sino S2316), with natural illumination, in the same time slot, without using the dental unit lamp. The results were recorded in an ad-hoc form and rates and confidence interval were obtained. Shade prevalence percentages (95% CI) were: A1: 46.2 (38.83 - 53.68); followed by A2 and B2, both with 17.39 (12.21 - 23.66); A3: 6.52 (3.41-11.11); B1: 4.35 (1.9-8.39); D2: 2.72 (0.89 - 6.23); B3: 2.17 (0.60-5.47) and C2: 1.09 (0.13-3.87); D3, C3, A3.5 and A4: 0.54 (0.01-2.99). Shades D1 and C1 were not determined in any subject. Within the conditions of this study, A1 was the most prevalent shade in central incisors, followed by A2 and B2.


El objetivo de este estudio fue evaluar la prevalencia de color dental en estudiantes de odontología de la Universidad de Buenos Aires (UBA). Los participantes fueron 184 estudiantes de cuarto año de la carrera de Odontología (157 mujeres y 27 hombres) de entre veintiuno y treinta tres años, con un promedio de edad de 24,45 (DE 2,79) años que aceptaron participar mediante consentimiento informado. Criterios de exclusión: quienes hayan recibido blanqueamiento en los últimos seis meses, tenían una restauración periférica total o parcial, pigmentaciones, fractura, lesiones cariosas y/o no cariosas en el incisivo central superior derecho (1.1) o éste estaba ausente. Se realizó profilaxis dental en la superficie bucal de cada 1.1 con un cepillo ad-hoc (TDV) montado en un micromotor de baja velocidad Kavo 2068 CHC (Alemania) y un contra-ángulo Kavo LUX K201 (Alemania). La medición del color se llevó a cabo en el tercio medio de cada 1.1, por el mismo observador, en la misma clínica dental, con iluminación natural en la misma franja horaria y sin utilizar la lámpara del equipo dental. Se utilizó un espectrofotómetro VITA Easyshade V (Zahnfabrikn Bad Säckingen, Alemania) que se calibró antes de cada determinación de acuerdo con las instrucciones del fabricante. Los resultados se registraron en una planilla ad-hoc y se obtuvieron tasas e intervalos de confianza. Prevalencia de colores % (IC 95%): A1: 46,2 (38,83 - 53,68), seguido de A2 y B2 ambos con 17,39 (12,21 - 23,66), A3: 6,52 (3,41-11,11), B1: 4,35 ( 1,9- 8,39), D2: 2,72 (0,89 - 6,23), B3: 2,17 (0,60-5,47) y C2: 1,09 (0,13- 3,87); D3, C3, A3.5 y A4: 0.54 (0.01-2.99) D1 y C1 no se determinaron en ningún sujeto. Dentro de las condiciones de este estudio A1 fue el color más prevalente en los incisivos centrales de estudiantes de odontología, seguido de A2 y B2.


Assuntos
Pigmentação em Prótese , Dente , Masculino , Humanos , Feminino , Adulto Jovem , Adulto , Pigmentação em Prótese/métodos , Estudantes de Odontologia , Cor , Universidades , Argentina , Faculdades de Odontologia , Espectrofotometria/métodos
11.
Food Res Int ; 161: 111836, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36192968

RESUMO

The development of portable NIR instruments facilitates widespread use among non-specialists. However, untrained operators may follow non-optimal measurement procedures. This work investigates how different factors in the measurement procedure influence the spectra of pig feed samples produced by SCiO, a handheld NIR. Measurement conditions were studied by means of Design of Experiments and evaluated with analysis of variance - simultaneous component analysis (ANOVA-SCA or ASCA). We quantified and visualized how measurement distance, angle, background lighting, the use of plastic lids and different devices interactively affect the resulting spectra. The samples could be distinguished with 100% accuracy with Partial Least Squares-Discriminant Analysis (PLS-DA) a scanning distance of 0.5 cm. Replication of the experiment with special attention to reproducing the conditions still lead to some differences, which highlights both the challenges in controlling conditions and the importance of considering them. Based on the results, generalizable guidelines for acceptance of spectra were proposed for this case study. Of main importance are performing measurements at distances of 0.5 cm or at least in an environment without background lighting. Overall, the provided guidelines for measurement conditions and a methodology to investigate this for other devices are a key enabler to spreading handheld spectrometry to a non-expert audience.


Assuntos
Plásticos , Espectroscopia de Luz Próxima ao Infravermelho , Animais , Análise Discriminante , Análise dos Mínimos Quadrados , Espectrofotometria , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Suínos
12.
Molecules ; 27(19)2022 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-36234857

RESUMO

This study describes the non-covalent interactions of the charge transfer complex (CT), which was responsible for the synthesis of Linagliptin (LNG) with 2,3-Dichloro-5,6-Dicyano-1,4-benzoquinone (DDQ), or with Chloranilic acid (CHA) complexes in acetonitrile (MeCN) at temperatures of (25 ± 2 °C). Then, a UV-Vis spectrophotometer was utilized to identify Linagliptin (LNG) from these complexes. For the quantitative measurement of Linagliptin in bulk form, UV-Vis techniques have been developed and validated in accordance with ICH criteria for several aspects, including selectivity, linearity, accuracy, precision, LOD, LOQ, and robustness. The optimization of the complex synthesis was based on solvent polarization; the ratio of molecules in complexes; the association constant; and Gibbs energy (ΔG°). The experimental work is supported by the computational investigation of the complexes utilizing density functional theory as well as (QTAIM); (NCI) index; and (RDG). According to the optimized conditions, Beer's law was observed between 2.5-100 and 5-100 µM with correlation coefficients of 1.9997 and 1.9998 for LGN-DDQ and LGN-CHA complexes, respectively. For LGN-DDQ and LGN-CHA complexes, the LOD and LOQ were (1.0844 and 1.4406 µM) and (3.2861 and 4.3655 µM), respectively. The approach was successfully used to measure LGN in its bulk form with high precision and accuracy.


Assuntos
Benzoquinonas , Linagliptina , Acetonitrilas , Solventes , Espectrofotometria/métodos , Termodinâmica
13.
Sensors (Basel) ; 22(19)2022 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-36236371

RESUMO

Volatile low-weight polycyclic aromatic hydrocarbons (PAHs) are known to be potentially toxic to humans and animals. Their detection in ambient air has been of great interest in recent years and various detection methods have been implemented. In this study, we used naphthalene as a basic model of such compounds and constructed our own version of a titanium oxide-based sensor system for its detection. The main goal of the study was to clearly demonstrate the effectiveness of this type of sensor, record its response under well-controlled conditions, and compare that response to concentration measurements made by the widely accepted spectrophotometric method. With that goal in mind, we recorded the sensor response while monitoring naphthalene vapor concentrations down to 95 nM as measured by spectrophotometry. Air flow over the sensor was passed continuously and sample measurements were made every 3 min for a period of up to 2 h. Over that period, several cycles of naphthalene contamination and cleaning were implemented and measurements were recorded. The relative humidity and temperature of the air being sampled were also monitored to assure no major variations occurred that could affect the measurements. The sensor showed high sensitivity and a reproducible response pattern to changes in naphthalene concentration. It could be easily "cleaned" of the compound in ten minutes by means of the application of UV light and the passing of fresh air. Pending testing with other volatile PAH, this type of sensor proves to be an effective and inexpensive way to detect naphthalene in air.


Assuntos
Poluentes Atmosféricos , Hidrocarbonetos Policíclicos Aromáticos , Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Humanos , Naftalenos , Hidrocarbonetos Policíclicos Aromáticos/análise , Espectrofotometria , Titânio , Raios Ultravioleta
14.
Sci Rep ; 12(1): 17231, 2022 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-36280772

RESUMO

Plasmonic nanoparticles are widely used in multiple scientific and industrial applications. Although many synthesis methods have been reported in the literature throughout the last decade, controlling the size and shape of large populations still remains as a challenge. As size and shape variations have a strong impact in their plasmonic properties, the need to have metrological techniques to accurately characterize their morphological features is peremptory. We present a new optical method referred as Dark-Field Single Particle Spectrophotometry which is able to measure the individual sizes of thousands of particles with nanometric accuracy in just a couple of minutes. Our method also features an easy sample preparation, a straightforward experimental setup inspired on a customized optical microscope, and a measurement protocol simple enough to be carried out by untrained technicians. As a proof of concept, thousands of spherical nanoparticles of different sizes have been measured, and after a direct comparison with metrological gold standard electron microscopy, a discrepancy of 3% has been attested. Although its feasibility has been demonstrated on spherical nanoparticles, the true strengthness of the method is that it can be generalized also to nanoparticles with arbitrary shapes and geometries, thus representing an advantageous alternative to the gold-standard electron microscopy.


Assuntos
Nanopartículas Metálicas , Espectrofotometria , Microscopia Eletrônica , Tamanho da Partícula
15.
Rev Sci Instrum ; 93(9): 094101, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-36182516

RESUMO

We present a spectrophotometer (optical density meter) combined with electromagnets dedicated to the analysis of suspensions of magnetotactic bacteria. The instrument can also be applied to suspensions of other magnetic cells and magnetic particles. We have ensured that our system, called MagOD, can be easily reproduced by providing the source of the 3D prints for the housing, electronic designs, circuit board layouts, and microcontroller software. We compare the performance of our system to existing adapted commercial spectrophotometers. In addition, we demonstrate its use by analyzing the absorbance of magnetotactic bacteria as a function of their orientation with respect to the light path and their speed of reorientation after the field has been rotated by 90°. We continuously monitored the development of a culture of magnetotactic bacteria over a period of 5 days and measured the development of their velocity distribution over a period of one hour. Even though this dedicated spectrophotometer is relatively simple to construct and cost-effective, a range of magnetic field-dependent parameters can be extracted from suspensions of magnetotactic bacteria. Therefore, this instrument will help the magnetotactic research community to understand and apply this intriguing micro-organism.


Assuntos
Campos Magnéticos , Magnetismo , Imãs , Espectrofotometria/métodos , Suspensões
16.
Anal Biochem ; 657: 114890, 2022 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-36096183

RESUMO

Analyzing a drug based on its overlapping spectra requires the use of sophisticated equipment and more hazardous solvents, which is detrimental to ecological sustainability. There is a critical need to create a simple, unique, and cost-effective approach for detecting a mixture of compounds in a safer environment. The aim was to develop an eco-friendly, stability-indicating assay method to determine Chlorthalidone (CLD) and Cilnidipine (CIL) in bulk and tablet dosage form using four different Ultra-Violet (UV) spectrophotometric methods. The ratio difference method showed absorbance peaks at 256.01 nm, 220.87 nm, first ratio difference spectra at 267.21 nm, 288.03 nm, and second ratio difference spectra at 309.2 nm, 280.03 nm. The area under curve techniques showed an absorbance range of around 224-232 nm for CIL and 218-227 nm for CLD. Further, the spectral changes have been assessed at various conditions like acid, base, oxidation, and UV radiation, and it has been found that CLD tends to lose its spectral property by more than 45%. The method developed for two drugs has obeyed Beers law with the selected concentration range of 7-13 µg/mL for CLD and 8.75-16.25 µg/mL for CIL. The developed method was finally evaluated using four tools, and the results showed green pictographically representation in the GAPI and score near to 100 for AES and closer to 1 for AGREE indicated that the method was found to be most eco-friendly. The findings were easy to replicate, adoptive with major regulatory requirements, environmentally friendly, fast, and inexpensive to perform. This approach does not require any specific expensive equipment, and it might be inexpensive to use in the future to assess laboratory and commercial mixtures.


Assuntos
Clortalidona , Fenofibrato , Di-Hidropiridinas , Propano/análogos & derivados , Solventes , Espectrofotometria/métodos , Comprimidos
17.
Molecules ; 27(17)2022 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-36080464

RESUMO

An ultrasound-assisted, one-pot cloud point extraction was developed for the determination of iron in vegetable samples by UV-Visible spectrophotometry. This method was based on the complexation of iron with an environmentally-friendly natural chelating agent extracted from Dipterocarpus intricatus Dyer fruit at pH 5.5 in the presence of Triton X-114. Reagent extraction, complexation, and preconcentration were performed simultaneously using ultrasound-assisted extraction at 45 °C. The surfactant-rich phase was diluted with ethanol and loaded through a syringe barrel packed with cotton that acted as a filter to trap the reagent powder. Analyte-entrapped on cotton was eluted using 0.1 mol·L-1 nitric acid solution. Filtrate and eluate solutions were measured absorbance of the dark-blue product at 575 nm. Influential parameters for the procedure were investigated. Under the optimum experimental conditions, the calibration curve was linear, ranging from 0.1 to 1.0 mg·L-1 with r2 = 0.997. Limits of detection and quantification were 0.03 and 0.09 mg·L-1, respectively while precision values of intra-day and inter-day were less than 5%. Recovery at 0.5 mg·L-1 ranged from 89.0 to 99.8%, while iron content in vegetable samples ranged from 2.45 to 13.36 mg/100 g. This method was cost-effective, reliable, eco-friendly, and convenient as a green analytical approach to determining iron content.


Assuntos
Frutas , Ferro , Quelantes , Concentração de Íons de Hidrogênio , Ligantes , Octoxinol , Espectrofotometria/métodos , Verduras
18.
Sensors (Basel) ; 22(17)2022 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-36080806

RESUMO

Tumor-derived exosomes may provide biomarkers for cancer treatment. Using sputtering technology, an affinity-based device to capture exosomes was developed using nanoporous substrate (NPG)-coated silicon microscopy. Immunology-based techniques detect and purify exosomes using gold coating with a specific antigen. Inverted fluorescent microscopy was used to detect target exosomes quantitatively utilizing fluorescent nanospheres as the label. We quantified the expression of CD63 surface protein markers on exosomes from conditioned culture media of breast cancer cells. The exosomes that targeted specific proteins with controls were statistically analyzed and compared to those that targeted non-specific proteins. Results from SEM showed that the exosomes were circular, between 30 and 150 nanometers in size. The porous gold substrates captured more exosomes than the nonporous substrates. Nitric acid treatments at different times resulted in a variety of pore sizes. Despite the increase in the size of the pores, the number of exosomes found in the porous gold substrate treated for 10 min nearly doubled compared to the one treated for 5 min. In this work, a fluorescence biosensor was developed to detect breast cancer exosomes using nanoporous gold substrates (NPG). Assay and model exosomes of specific breast cancer cells showed that exosomes exhibit diagnostic surface protein markers, reflecting the protein profile of their parent cells. Furthermore, the specific binding between the exosome surface antibodies and the targets identified the CD63 biomarkers on the exosome, suggesting these markers' diagnostic potential. This study can accelerate exosome research in determining tumor-related exosomes and develop novel cancer diagnostic methods.


Assuntos
Neoplasias da Mama , Exossomos , Nanoporos , Biomarcadores/metabolismo , Biomarcadores Tumorais , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Exossomos/metabolismo , Feminino , Ouro , Humanos , Proteínas de Membrana/metabolismo , Espectrofotometria
19.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 4700-4703, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-36086277

RESUMO

In the past half-century, the advent of solid-state electronics, i.e., microcontrollers, transistors, photodiodes, light-emitting diodes and more, has led to the improvement of the tools we, as a human race, need and use in our daily lives. Solid-state electronics has specifically contributed significantly to the field of biomedical engineering and has allowed various round-the-clock point-of-care testing applications. These include handheld, wearable, and implantable sensors and devices for accelerated interventions. Furthermore, miniaturization has accelerated the implementation of low-cost and energy-efficient systems with increased performance. In this paper, we have used optical techniques along with the benefits of solid-state electronics to measure bilirubin concentration in plasma with concentrations projected from healthy individuals to hyperbilirubinemia (0 - 30 mg/dL). Traditionally, full-range spectrophotometry is the gold standard optical method and provides the most accurate results but suffers from instrument complexity. Thus, this paper proposes and investigates the measurement of bilirubin by using a dual-wavelength approach combined with photodegradation kinetics. By tracking the changes in the spectral characteristics of bilirubin for 10 minutes (~3 J/cm2), a new model was built to measure bilirubin concentrations and distinguish between low vs high and risky vs non-risky levels. Results show a high positive correlation between the optical responses and concentration (R-square > 0.93) with an average accuracy of ~1.4 mg/dL. On top of that, the technique's viability for point-of-care testing of bilirubin levels was studied using a system-on-chip optical module. Thus, this could help suggest neonatal therapeutic interventions, including enteral feeding, phototherapy, and blood transfusion.


Assuntos
Bilirrubina , Fototerapia , Humanos , Hiperbilirrubinemia/diagnóstico , Recém-Nascido , Fototerapia/métodos , Espectrofotometria
20.
Forensic Sci Int ; 340: 111422, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36037597

RESUMO

The correct definition of time of death often represents a key to solving judicial cases. One of the methods for determination of the time interval since death is at present the quantitative and qualitative characteristics of hypostases. However, the simple observation of the degree and fixation of hypostases is based on nonobjective parameters, and is therefore characterized by an intrinsic variability that can compromise their reliability. The purpose of the present study was to define an objective and standardizable method that allows estimation of time since death with good approximation. To achieve this, the instrument used was based on spectrophotometry, to analyze only the hemoglobin contribution to skin color, while excluding the role of melanin. This made it possible to analyze a hypostatic area, with a numerical value defined as a measure of the hemoglobin content before and after application of standardized pressure for a defined time interval. The study was conducted on 100 cadavers in various wards. The variables considered in the study were: Hb-pre (mean hemoglobin measure before weight force application); Hb-post (mean hemoglobin measure after weight force application), ΔHb (change in mean hemoglobin measures from before to after weight force application); and red% Hb (percentage reduction in hemoglobin after weight force application, compared to the mean measure of hemoglobin before weight force application). The analysis showed statistically significant correlations between red% Hb in the skin area analyzed and time from death to examination. This provided a mathematical formula to estimate time since death with good reliability ( ± 4 h, 50 min).


Assuntos
Melaninas , Mudanças Depois da Morte , Hemoglobinas/análise , Humanos , Reprodutibilidade dos Testes , Espectrofotometria
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