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1.
Anal Chim Acta ; 1083: 110-118, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31493801

RESUMO

A paper-based analytical device (PAD) with an integrated composite electrode for non-enzymatic creatinine sensing was developed. The electrode was produced and optimization was efficiently accomplished using a rapid digital dispensing approach. The electrochemical sensor was fabricated using an HP D300 digital dispenser to deliver a copper oxide and ionic liquid composite onto an electrochemically reduced graphene modified screen-printed carbon electrode (CuO/IL/ERGO/SPCE) on a PAD. The modified electrode was characterized using electrochemical and microscopic techniques. Electrochemical detection of creatinine was performed on the SPCE using amperometry at a constant potential. Under optimized conditions, the paper-based sensor exhibited a linear range of 0.01-2.0 mM (R2 = 0.99) and the limit of detection was 0.22 µM (S/N = 3, IUPAC definition) for creatinine. The simple fabrication process, low cost, and clinically appropriate creatinine sensitivity make this device applicable for point-of-care use.


Assuntos
Cobre/química , Creatinina/sangue , Grafite/química , Líquidos Iônicos/química , Papel , Carbono/química , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Humanos , Limite de Detecção , Técnicas Analíticas Microfluídicas/instrumentação , Técnicas Analíticas Microfluídicas/métodos , Reprodutibilidade dos Testes
2.
Anal Chim Acta ; 1083: 150-156, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31493805

RESUMO

Most of the on-site approaches for inferring of the post-mortem interval are still based on observative data from the direct body inspection, whereas, objective and quantitative analyses, such as potassium in the vitreous humor, are require laboratory instrumentation and skilled personnel. The present paper presents a simple and low cost analytical method suitable for use at the crime scene for inferring the time since death. The method uses a microfluidic paper-based device (µPAD) for the determination of ammonium in the vitreous humor (VH) based on the selective interaction between the ammonium and the Nessler's reagent. The color change was measured in terms of "RGB distance" by using a simple and free smartphone application. The optimized device showed a limit of detection of 0.4 mmol L-1, with between days precision less than 9.3% expressed as relative standard deviation, and accuracy between days from 94.5% to 104.5%. The selectivity of the Nessler's reaction was tested towards the main vitreous humor compounds, and no significant interferences were found. This paper-based analytical device was successfully used for the determination of ammonium ion in VH samples from forensic autopsies. The results obtained with the proposed method, although for a limited number of cases (n = 25), showed a close correlation with the data obtained with an instrumental analysis based on capillary electrophoresis. Moreover, in order to make the evaluation of results as simple as possible, a direct correlation between the color intensity, expressed as RGB distance, and the post-mortem interval was studied and a significant correlation was found (R2 > 0.78). In conclusion, the present preliminary study showes that the proposed device could be an additional tool to the traditional methods for a more accurate, although still presumptive, estimation of the time of death directly at the crime scene.


Assuntos
Compostos de Amônio/análise , Medicina Legal/métodos , Papel , Mudanças Depois da Morte , Corpo Vítreo/química , Adulto , Idoso , Colorimetria/instrumentação , Colorimetria/métodos , Medicina Legal/instrumentação , Humanos , Iodetos/química , Limite de Detecção , Compostos de Mercúrio/química , Técnicas Analíticas Microfluídicas/instrumentação , Técnicas Analíticas Microfluídicas/métodos , Pessoa de Meia-Idade , Estudo de Prova de Conceito , Reprodutibilidade dos Testes , Fatores de Tempo , Adulto Jovem
3.
Anal Bioanal Chem ; 411(21): 5415-5422, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31317237

RESUMO

Isoelectric focusing (IEF), a powerful technique for protein separation and enrichment, was successfully integrated into microfluidic paper-based analytical devices (µPADs) in this work. The µPADs for isoelectric focusing were fabricated by octadecyltrichlorosilane (OTS) silanization and subsequent region-selective plasma treatment. The system of IEF on µPADs could be easily assembled. And a series of conditions of the system were investigated, including the suitable concentration of ampholyte to create good pH gradient, the effect of polyvinylpyrrolidone (PVP) on electroosmotic flow (EOF) suppression, and focusing voltage applied on the paper channel. After optimization, simultaneous separation and enrichment of protein sample containing myoglobin and cytochrome C was successfully demonstrated. Besides, parallel IEF on multichannels were also achieved for the separation of multiple protein samples on one single chip, and their performance was compared with that of the conventional gel-IEF system. The developed IEF on µPADs exhibits appealing features such as low cost, simplicity, and disposability and are believed to have great application potentials.


Assuntos
Focalização Isoelétrica , Técnicas Analíticas Microfluídicas/métodos , Papel , Citocromos c/isolamento & purificação , Eletro-Osmose , Concentração de Íons de Hidrogênio , Mioglobina/isolamento & purificação , Povidona/química , Silanos/química
4.
Virchows Arch ; 475(3): 313-323, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31267199

RESUMO

Breast cancer is a highly heterogeneous disease. The efficacy of tailored therapeutic strategies relies on the precise detection of diagnostic biomarkers by immunohistochemistry (IHC). Therefore, considering the increasing incidence of breast cancer cases, a concomitantly time-efficient and accurate diagnosis is clinically highly relevant. Microfluidics is a promising innovative technology in the field of tissue diagnostic, enabling for rapid, reliable, and automated immunostaining. We previously reported the microfluidic-based HER2 (human epidermal growth factor receptor 2) detection in breast carcinomas to greatly correlate with the HER2 gene amplification level. Here, we aimed to develop a panel of microfluidic-based IHC protocols for prognostic and therapeutic markers routinely assessed for breast cancer diagnosis, namely HER2, estrogen/progesterone receptor (ER/PR), and Ki67 proliferation factor. The microfluidic IHC protocol for each marker was optimized to reach high staining quality comparable to the standard procedure, while concomitantly shortening the staining time to 16 min-excluding deparaffinization and antigen retrieval step-with a turnaround time reduction up to 7 folds. Comparison of the diagnostic score on 50 formaldehyde-fixed paraffin-embedded breast tumor resections by microfluidic versus standard staining showed high concordance (overall agreement: HER2 94%, ER 95.9%, PR 93.6%, Ki67 93.7%) and strong correlation (ρ coefficient: ER 0.89, PR 0.88, Ki67 0.87; p < 0.0001) for all the analyzed markers. Importantly, HER2 genetic reflex test for all discordant cases confirmed the scores obtained by the microfluidic technique. Overall, the microfluidic-based IHC represents a clinically validated equivalent approach to the standard chromogenic staining for rapid, accurate, and automated breast cancer diagnosis.


Assuntos
Neoplasias da Mama/diagnóstico , Técnicas Analíticas Microfluídicas/métodos , Microfluídica/métodos , Biomarcadores Tumorais/metabolismo , Mama/patologia , Feminino , Humanos , Imuno-Histoquímica/métodos , Hibridização in Situ Fluorescente , Antígeno Ki-67/metabolismo , Prognóstico , Receptor ErbB-2/metabolismo , Receptores Estrogênicos/metabolismo , Receptores de Progesterona/metabolismo
5.
Anal Chim Acta ; 1076: 110-117, 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31203954

RESUMO

Encoded hydrogel microparticles, synthesized by Stop Flow Lithography (SFL), have shown great potential for microRNA assays for their capability to provide high multiplexing capacity and solution-like hybridization kinetics. However, due to the low conversion of copolymerization during particle synthesis, current hydrogel microparticles can only utilize ∼10% of the input probes that functionalize the particles for miRNA assay. Here, we present a novel method of functionalizing hydrogel microparticles after particle synthesis by utilizing unconverted double bonds remaining inside the hydrogel particles to maximize functional probe incorporation and increase the performance of miRNA assay. This allows covalent bonding of functional probes to the hydrogel network after particle synthesis. Because of the abundance of the unconverted double bonds and accessibility of all probes, the probe density increases about 8.2 times compared to that of particles functionalized during the synthesis. This results lead to an enhanced miRNA assay performance that improves the limit of detection from 4.9 amol to 1.5 amol. In addition, higher specificity and shorter assay time are achieved compared to the previous method. We also demonstrate a potential application of our particles by performing multiplexed miRNA detections in human plasma samples.


Assuntos
Hidrogéis/química , MicroRNAs/sangue , Biomarcadores/sangue , DNA/química , DNA/genética , Sondas de DNA/química , Sondas de DNA/genética , Humanos , Hidrogéis/síntese química , Dispositivos Lab-On-A-Chip , MicroRNAs/genética , Técnicas Analíticas Microfluídicas/métodos , Hibridização de Ácido Nucleico , Polietilenoglicóis/química , Porosidade
6.
Anal Chim Acta ; 1076: 118-124, 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31203955

RESUMO

The quantification of low concentration proteins can facilitate the discovery of some significant biomarkers, and provide us a more profound understanding of cell heterogeneity when applied to single cell analysis. However, most state-of- art single cell protein detection platforms are bulky, expensive and complicated. Here we report a simple and low cost microfluidic dPCR (digital polymerase chain reaction) chip-based proximity ligation assay (PLA) for the quantification of low concentration proteins. First, standard hCSTB (human cystatin B) protein was used to optimize the related experimental conditions. Comparing to ordinary PLA tests, the results showed that our method achieved femtomolar limit of detection (LOD) with a linear dynamic range over three to four orders of magnitude. Then human CD147 protein, a reported biomarker for hepatoma carcinoma, was detected in single HepG2 and L02 cells. The results showed that there were wide disparities in single cell CD147 abundance for both of the two cell lines. And the average CD147 protein content in single HepG2 cells displayed 2-fold increase in comparison to that in single L02 cells. Comparing to the research findings obtained at bulk level, our method can provide more useful information for diagnosis and targeted therapy of tumors.


Assuntos
Basigina/análise , Cistatina B/análise , Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas/métodos , Biomarcadores Tumorais/análise , Linhagem Celular Tumoral , Humanos , Limite de Detecção , Técnicas Analíticas Microfluídicas/instrumentação , Reação em Cadeia da Polimerase/instrumentação , Reação em Cadeia da Polimerase/métodos , Análise de Célula Única/instrumentação , Análise de Célula Única/métodos
7.
Anal Chim Acta ; 1076: 154-161, 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31203960

RESUMO

Cancer cell detection in liquid biopsies has been a widely studied application in many microfluidic devices. The use of a common antibody, such as the epithelial cell adhesion molecule (Anti-EpCAM) or other specific antibodies, has facilitated the detection and study of many cancers. However, the use of such antibodies requires a priori knowledge of the cancer source, and many cancer subtypes are missed in screening applications. There remains a need to study a wider range of cancers that maintain the streamlined antibody approach in cell affinity separations. The Human transferrin receptor (CD71) has recently been demonstrated as a cancer cell affinity target in blood samples. CD71 expression in blood cells is low, whereas proliferating cancer cells have a higher expression of the surface protein. CD71 expression is variable with cell cycle, which can impact cell separations. In this work, we investigated the effects of cell cycle and CD71 expression on cell capture metrics. Six cancer cell lines were isolated from blood via CD71 affinity capture, with a capture efficiency and purity that varied with CD71 expression. Despite variation in CD71 expression, the affinity was sufficient to isolate cancer cells spiked into blood; under optimal conditions, CD71-based capture resulted in capture purity >80%. We conclude that CD71 affinity separations show potential as a biomarker for cancer studies without sacrificing sensitivity and selectivity, and that cancer cells can be isolated from liquid biopsies over a range of expression of the target protein.


Assuntos
Antígenos CD/imunologia , Biomarcadores Tumorais/imunologia , Células Neoplásicas Circulantes/imunologia , Receptores da Transferrina/imunologia , Anticorpos Monoclonais/imunologia , Linhagem Celular Tumoral , Citometria de Fluxo/instrumentação , Citometria de Fluxo/métodos , Humanos , Imunoensaio/instrumentação , Imunoensaio/métodos , Dispositivos Lab-On-A-Chip , Ligantes , Biópsia Líquida , Técnicas Analíticas Microfluídicas/instrumentação , Técnicas Analíticas Microfluídicas/métodos
9.
Nat Commun ; 10(1): 2741, 2019 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-31227695

RESUMO

Knowing how biomarker levels vary within biological fluids over time can produce valuable insight into tissue physiology and pathology, and could inform personalised clinical treatment. We describe here a wearable sensor for monitoring biomolecule levels that combines continuous fluid sampling with in situ analysis using wet-chemical assays (with the specific assay interchangeable depending on the target biomolecule). The microfluidic device employs a droplet flow regime to maximise the temporal response of the device, using a screw-driven push-pull peristaltic micropump to robustly produce nanolitre-sized droplets. The fully integrated sensor is contained within a small (palm-sized) footprint, is fully autonomous, and features high measurement frequency (a measurement every few seconds) meaning deviations from steady-state levels are quickly detected. We demonstrate how the sensor can track perturbed glucose and lactate levels in dermal tissue with results in close agreement with standard off-line analysis and consistent with changes in peripheral blood levels.


Assuntos
Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas/instrumentação , Sistemas Automatizados de Assistência Junto ao Leito , Pele/química , Dispositivos Eletrônicos Vestíveis , Biomarcadores/análise , Glicemia/análise , Desenho de Equipamento , Glucose/análise , Voluntários Saudáveis , Humanos , Ácido Láctico/análise , Microdiálise/instrumentação , Microdiálise/métodos , Técnicas Analíticas Microfluídicas/métodos
10.
Analyst ; 144(14): 4162-4174, 2019 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-31166335

RESUMO

Cell-free (cf) nucleic acids are considered important and have been used as selective biomarkers. Conventional techniques for cf nucleic acid biomarker isolation from blood are generally time-consuming, complicated, and expensive. This study describes a lab-on-a-disk system equipped with newly developed immiscible filtration assisted by surface tension (IFAST), which can achieve the rapid isolation of cfDNA from whole blood. The principle of centrifugal IFAST (C-IFAST) is introduced. An arch-like channel for magnetic bead transfer in the immiscible phase is designed, which builds both a virtual water-air "wall" and an air-oil "wall" to prevent the blending of water and oil. The entire process requires less than 15 min and achieves the recovery of 65% of cfDNA from plasma and 30% from whole blood. Experiments were performed to test the validity of the chip, showing that this technique takes less time to obtain results of identical quality compared to commercial kits. The proposed C-IFAST method enables rapid and reliable cfDNA isolation from large whole blood volume (4 ml) and can potentially be used in "liquid biopsy" point-of-care diagnosis.


Assuntos
Ácidos Nucleicos Livres/sangue , DNA Viral/sangue , Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas/métodos , Biomarcadores/sangue , Filtração , Vírus da Hepatite B/genética , Humanos , Biópsia Líquida/métodos , Fenômenos Magnéticos , Técnicas Analíticas Microfluídicas/instrumentação , Reprodutibilidade dos Testes
11.
Analyst ; 144(13): 3925-3935, 2019 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-31094395

RESUMO

Sepsis, a life-threatening syndrome that contributes to millions of deaths annually worldwide, represents a moral and economic burden to the healthcare system. Although no single, or even a combination of biomarkers has been validated for the diagnosis of sepsis, multiple studies have shown the high specificity of CD64 expression on neutrophils (nCD64) to sepsis. The analysis of elevated nCD64 in the first 2-6 hours after infection during the pro-inflammatory stage could significantly contribute to early sepsis diagnosis. Therefore, a rapid and automated device to periodically measure nCD64 expression at the point-of-care (POC) could lead to timely medical intervention and reduced mortality rates. Current accepted technologies for measuring nCD64 expression, such as flow cytometry, require manual sample preparation and long incubation times. For POC applications, however, the technology should be able to measure nCD64 expression with little to no sample preparation. In this paper, we demonstrate a smartphone-imaged microfluidic biochip for detecting nCD64 expression in under 50 min. In our assay, first unprocessed whole blood is injected into a capture chamber to immunologically capture nCD64 along a staggered array of pillars, which were previously functionalized with an antibody against CD64. Then, an image of the capture channel is taken using a smartphone-based microscope. This image is used to measure the cumulative fraction of captured cells (γ) as a function of length in the channel. During the image analysis, a statistical model is fitted to γ in order to extract the probability of capture of neutrophils per collision with a pillar (ε). The fitting shows a strong correlation with nCD64 expression measured using flow cytometry (R2 = 0.82). Finally, the applicability of the device to sepsis was demonstrated by analyzing nCD64 from 8 patients (37 blood samples analyzed) along the time they were admitted to the hospital. Results from this analysis, obtained using the smartphone-imaged microfluidic biochip were compared with flow cytometry. Again, a correlation coefficient R2 = 0.82 (slope = 0.99) was obtained demonstrating a good linear correlation between the two techniques. Deployment of this technology in ICU could significantly enhance patient care worldwide.


Assuntos
Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas/métodos , Neutrófilos/imunologia , Receptores de IgG/sangue , Sepse/diagnóstico , Smartphone , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/sangue , Feminino , Citometria de Fluxo , Humanos , Masculino , Técnicas Analíticas Microfluídicas/instrumentação , Pessoa de Meia-Idade , Testes Imediatos
12.
J Nanobiotechnology ; 17(1): 71, 2019 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-31133019

RESUMO

The incidence of lung cancer continues to rise worldwide. Because the aggressive metastasis of lung cancer cells is the major drawback of successful therapies, the crucial challenge of modern nanomedicine is to develop diagnostic tools to map the molecular mechanisms of metastasis in lung cancer patients. In recent years, microfluidic platforms have been given much attention as tools for novel point-of-care diagnostic, an important aspect being the reconstruction of the body organs and tissues mimicking the in vivo conditions in one simple microdevice. Herein, we present the first comprehensive overview of the microfluidic systems used as innovative tools in the studies of lung cancer metastasis including single cancer cell analysis, endothelial transmigration, distant niches migration and finally neoangiogenesis. The application of the microfluidic systems to study the intercellular crosstalk between lung cancer cells and surrounding tumor microenvironment and the connection with multiple molecular signals coming from the external cellular matrix are discussed. We also focus on recent breakthrough technologies regarding lab-on-chip devices that serve as tools for detecting circulating lung cancer cells. The superiority of microfluidic systems over traditional in vitro cell-based assays with regard to modern nanosafety studies and new cancer drug design and discovery is also addressed. Finally, the current progress and future challenges regarding printable and paper-based microfluidic devices for personalized nanomedicine are summarized.


Assuntos
Neoplasias Pulmonares/diagnóstico , Técnicas Analíticas Microfluídicas/métodos , Nanoestruturas/química , Animais , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Materiais Biomiméticos/química , Movimento Celular , Humanos , Dispositivos Lab-On-A-Chip , Neoplasias Pulmonares/irrigação sanguínea , Neoplasias Pulmonares/patologia , Técnicas Analíticas Microfluídicas/instrumentação , Nanomedicina , Nanoestruturas/efeitos adversos , Metástase Neoplásica , Células Neoplásicas Circulantes/metabolismo , Células Neoplásicas Circulantes/patologia , Nanomedicina Teranóstica , Microambiente Tumoral
13.
Analyst ; 144(11): 3556-3566, 2019 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-31050348

RESUMO

Haematological diseases significantly increase RBC aggregation. Specifically, RBC aggregation is considerably varied by haematological factors including cellular properties, and suspending medium properties. Thus, in order to ensure consistent measurement of RBC aggregation, it is necessary to measure RBC aggregation and blood pressure simultaneously. Here, a method for simultaneously measuring RBC aggregation and blood pressure is demonstrated by analyzing blood flows supplied from a disposable air-compressed pump. A microfluidic device is composed of two parallel microfluidic channels (i.e., PBS channel and blood channel), an inlet, and outlets. After the PBS channel is filled with the PBS solution, the outlets of the PBS channel are completely closed with two pinch valves. Under varying blood flow rates of the disposable pump, the blood pressure index (PI) is quantified by analyzing the image intensity of RBCs in the PBS channel. Thereafter, at stasis, the RBC aggregation index (AI) is calculated by analyzing the image intensity of blood in the blood channel. First, under a constant blood flow-rate of a syringe pump, the image intensity of RBCs collected in the PBS channel (IPC) is linearly proportional to blood pressure estimated in the blood channel (PBC). Second, with respect to variations in the blood flow-rate of the proposed pump, the IPC and PBC decrease gradually over time. Two blood pressure indices (PI [PBC], and PI [IPC]) are obtained by averaging temporal variations in the PBC and IPC, respectively. The results of the regression analysis indicate that the coefficient of the linear regression yields a higher value of R2 = 0.9051. Subsequently, the PI (IPC) is effectively used to estimate blood pressure. Finally, the variations in blood pressure and RBC aggregation are obtained by using aggregation-enhanced blood samples and deformability-reduced blood samples. Thus, the proposed method leads to consistent variations in the PI and AI, when compared with the previous results. The experimental demonstrations indicate that two indices (PI and AI) are effectively used to simultaneously quantify blood pressure and RBC aggregation.


Assuntos
Pressão Sanguínea , Agregação Eritrocítica , Técnicas Analíticas Microfluídicas/métodos , Desenho de Equipamento , Hematócrito , Humanos , Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas/instrumentação , Análise de Regressão
14.
Anal Chim Acta ; 1071: 36-43, 2019 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-31128753

RESUMO

This study describes for the first time the development of 3D printed microfluidic devices with integrated electrodes for label-free counting of E. coli cells incorporated inside droplets based on capacitively coupled contactless conductivity detection (C4D). Microfluidic devices were fully fabricated by 3D printing in the T-junction shape containing two channels for disperse and continuous phases and two sensing electrodes for C4D measurements. The disperse phase containing E. coli K12 cells and the continuous phase containing oil and 1% Span® 80 were pumped through flow rates fixed at 5 and 60 µL min-1, respectively. The droplets with incorporated cells were monitored in the C4D system applying a 500-kHz sinusoidal wave with 1 Vpp amplitude. The generated droplets exhibited a spherical shape with average diameter of 321 ±â€¯9 µm and presented volume of 17.3 ±â€¯0.5 nL. The proposed approach demonstrated ability to detect E. coli cells in the concentration range between 86.5 and 8650 CFU droplet-1. The number of cells per droplet was quantified through the plate counting method and revealed a good agreement with the Poisson distribution. The limit of detection achieved for counting E. coli cells was 63.66 CFU droplet-1. The label-free counting method has offered instrumental simplicity, low cost, high sensitivity and compatibility to be integrated on single microfluidic platforms entirely fabricated by 3D printing, thus opening new possibilities of applications in microbiology.


Assuntos
Contagem de Células/métodos , Condutividade Elétrica , Técnicas Eletroquímicas/métodos , Escherichia coli K12/isolamento & purificação , Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas/métodos , Técnicas Eletroquímicas/instrumentação , Eletrodos , Limite de Detecção , Técnicas Analíticas Microfluídicas/instrumentação , Impressão Tridimensional
15.
Anal Chim Acta ; 1071: 44-52, 2019 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-31128754

RESUMO

A multifunctional microchip-based distillation apparatus is presented for the distilled of sulfur dioxide (SO2) in food products. The microchip is fabricated on poly(methyl methacrylate) (PMMA) substrates, and comprises a sample zone, a buffer zone, a serpentine distillation column, and a collection zone. In the process, the sample is introduced into the sample zone and is heated under carefully controlled temperature and time conditions. The resulting SO2 and water vapor are carried by nitrogen (N2) gas to the distillation column, where the SO2 is separated from the water vapor via the condensing effects of a continuous cold water flow. Finally, the SO2 is transported to the collection zone, where it is collected with hydrogen peroxide (H2O2) and its concentration determined using an alkali-based titration and paper-based detection method. A distillation efficiency of 90.5% is obtained under the optimal distillation conditions at concentrations of 20-4000 ppm. Moreover, a linear correlation (R2 = 0.9997) is observed between the experimental measurements of the SO2 concentration and the known concentration. The validity of the presented microchip-based distillation apparatus is further investigated by distilling the SO2 concentrations of 25 commodity samples. The detection results show that the deviation does not exceed 5.4% compared with the traditional official method.


Assuntos
Destilação/métodos , Técnicas Analíticas Microfluídicas/métodos , Dióxido de Enxofre/análise , Destilação/instrumentação , Contaminação de Alimentos/análise , Frutas/química , Dispositivos Lab-On-A-Chip , Limite de Detecção , Técnicas Analíticas Microfluídicas/instrumentação , Polimetil Metacrilato/química , Verduras/química
16.
Anal Chim Acta ; 1071: 59-69, 2019 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-31128756

RESUMO

Early diagnosis of cancer by biomarker detection has been widely studied since it can lead to an increase in patient survival rates. Magnetic nanoparticles (MNPs) play an important role in this field acting as a valuable tool in the biomarker immunocapture and detection. In this work, Co0.25Zn0.75Fe2O4 (CoZnFeONPs) nanoparticles were synthesized and applied as enzyme mimics of peroxidase-like catalysis in a disposable enzyme-free microfluidic immunoarray device (µID). The catalytic activity of CoZnFeONPs was evaluated by hydrogen peroxide detection using cyclic voltammetry and the apparent Michaelis-Menten constant was estimated by Lineweaver-Burk equation showing good Km values. In µID, the immunosensors were assembled with monoclonal antibody against CYFRA 21-1 covalently immobilized on graphene oxide previously deposited on the screen-printed carbon-based electrodes. Under optimized conditions, the method presented a good linear response for CYFRA 21-1 in the range of 3.9-1000 fg mL-1 achieving an ultralow limit of detection (LOD) of 0.19 fg mL-1. For comparison, Fe3O4 nanoparticles (FeONPs) was also synthetized and presented results slight inferior to that obtained with CoZnFeONPs. The methods developed using both MNPs exhibited countless advantages when compared with the immunosensors developed for CYFRA-21-1, previously reported in the literature. The methods were successful applied for the detection of CYFRA 21-1 in real serum samples of healthy and prostate cancer patients and showed good correlation with results obtained with the enzyme-linked immunosorbent assay (ELISA). The CoZnFeONPs associated with the disposable microfluidic immunoarray device provides a simple and effective method for biomarker detection that could satisfy the need for a low-cost and rapid test for early diagnosis of cancer.


Assuntos
Antígenos de Neoplasias/sangue , Biomarcadores Tumorais/sangue , Queratina-19/sangue , Dispositivos Lab-On-A-Chip , Nanopartículas Metálicas/química , Técnicas Analíticas Microfluídicas/métodos , Anticorpos/imunologia , Antígenos de Neoplasias/imunologia , Biomarcadores Tumorais/imunologia , Cobalto/química , Eletrodos , Grafite/química , Humanos , Imunoensaio/instrumentação , Imunoensaio/métodos , Ferro/química , Queratina-19/imunologia , Limite de Detecção , Masculino , Técnicas Analíticas Microfluídicas/instrumentação , Neoplasias da Próstata/sangue , Reprodutibilidade dos Testes , Zinco/química
17.
Rev Sci Instrum ; 90(4): 045002, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31042988

RESUMO

We developed and characterized a paper-based microfluidic sensor for the on-site diagnosis of drought stress in plants. Proline was used as a biomarker for analyzing drought stress, which was extracted by a colorimetric method using the proline-ninhydrin reaction. Paper was used as the main sensor material for the on-site detection of proline as it is easily transportable and cost-effective. The paper-based sensor was fabricated using wax-printing and origami methods, and the sensor was precoated with ninhydrin to allow for easy and convenient on-site use. Furthermore, a sample-to-ninhydrin ratio of 1:2 was found to confer optimal sensitivity to the drought diagnosis sensor. The concentration of proline in a sample was quantified by red-green-blue analysis to determine the change in green color intensity levels in response to distinct proline concentrations, which were detected by the sensor. The limit of detection of proline using the devised sensor was 657 µM, and the green color intensity level decreased with increasing proline concentration. In addition, the sensor was validated in an experimental drought stress model with Arabidopsis and subjected to drought stress for 21 days, and the amount of proline detected was 10 mM. The devised paper-based microfluidic sensor highlights the possibility of the on-site evaluation of drought stress in plants with potential to be utilized in various agricultural areas in the future.


Assuntos
Arabidopsis/química , Secas , Técnicas Analíticas Microfluídicas/instrumentação , Prolina/análise , Estresse Fisiológico , Arabidopsis/metabolismo , Desidratação/diagnóstico , Desidratação/metabolismo , Desenho de Equipamento , Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas/métodos , Ninidrina , Papel , Estresse Fisiológico/fisiologia
18.
Analyst ; 144(12): 3782-3789, 2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-31094378

RESUMO

We investigate the influence of rotational forces on blood dynamics in a microfluidic device. The special confluence of Coriolis force and blood rheology is brought forth by analyzing the flow at different hematocrit (volume fraction of red blood cells) levels and rotational speeds. We further study the effects of channel layout and alignment with regard to the axis of rotation to understand this intricate interplay. We provide a sound basis for efficient designing of a lab on a compact disc (lab on CD) platform by harnessing the effects of Coriolis force at relatively much lower rotational speeds, in sharp contrast with the reported findings where Coriolis effects have been considered to be effective only for exceptionally high rotational speeds. Our results show that over certain intermediate regimes of rotational speeds, the flow profiles for different hematocrit levels are noticeably different. This, in turn, could be harnessed as a possible diagnostic signature of the hematocrit (or equivalently, packed cell volume) level, without necessitating the deployment of chemical consumables, in an energy efficient paradigm.


Assuntos
Sangue , Discos Compactos , Força Coriolis , Hematócrito/métodos , Dispositivos Lab-On-A-Chip , Viscosidade Sanguínea , Hematócrito/instrumentação , Humanos , Técnicas Analíticas Microfluídicas/instrumentação , Técnicas Analíticas Microfluídicas/métodos , Rotação
19.
Ecotoxicol Environ Saf ; 178: 51-57, 2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-30991247

RESUMO

A novel platform to perform systematic analysis and direct reading of root elongation bioassays is presented. The device was designed to include multiplexed microenvironments for the germination and growth of individual seeds, which allows observation by the naked eye or by optical systems, notably cellphone cameras. Prototypes were fabricated by laser micromachining on a highly transparent material that is fully compatible with biological systems. The effectiveness of the milli-channel array was verified against the conventional system (Petri dish). Lactuca sativa was chosen as a model species and glyphosate as a typical toxic agent. All tests were run according to standardized procedures and data analysis was carried out through different statistical indicators such as the root elongation and germination indexes. Results attained in the milli-channel array were identical to those in Petri dish, with the remarkable benefit that several steps required in the conventional system were avoided, which enormously decreases the operation time and the possibility of experimental errors. Further advantages of the milli-channel array are also reported, such as the capability to achieve live imaging of plant organs growth through a simple experiment. The developed device has been proven to be effective, versatile, easy-to-use, and integrable to cellphones, which naturally provide facilities for data recording, analysis, and networking. These improvements open the route to novel applications of bioassays in the wide field of ecotoxicology and environmental studies.


Assuntos
Monitoramento Ambiental/métodos , Técnicas Analíticas Microfluídicas/métodos , Raízes de Plantas/crescimento & desenvolvimento , Smartphone , Poluentes do Solo/toxicidade , Bioensaio , Monitoramento Ambiental/instrumentação , Desenho de Equipamento , Germinação/efeitos dos fármacos , Alface/crescimento & desenvolvimento , Técnicas Analíticas Microfluídicas/instrumentação , Raízes de Plantas/efeitos dos fármacos , Sementes/efeitos dos fármacos , Sementes/crescimento & desenvolvimento
20.
Analyst ; 144(9): 2942-2953, 2019 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-30939180

RESUMO

Adipocyte hypertrophy and hyperplasia are important parameters in describing abnormalities in adipogenesis that are concomitant to diseases such as obesity, diabetes, anorexia nervosa and osteoporosis. Therefore, technical developments in the detection of adipocytes become an important driving factor in adipogenesis research. Current techniques such as optical microscopy and flow cytometry are available in detection and examination of adipocytes, driving cell- and molecular-based research of adipogenesis. Even though microscopy techniques are common and straightforward, they are restricted in terms of manipulation and separation of the cells. Flow cytometry is an alternative, but mature adipocytes are fragile and cannot withstand the flow process. Other separation methods usually require labeling of the cells or usage of microfluidic platforms that utilize fluids with different densities. Magnetic levitation is a novel label-free technology with the principle of movement of cells towards the lower magnetic field in a paramagnetic medium depending on their individual densities. In this study, we used a magnetic levitation device for density-based single cell detection of differentiated adipogenic cells in heterogeneous populations. Results showed that the magnetic levitation platform was sensitive to changes in the lipid content of mesenchymal stem cells committed to adipogenesis and it could be successfully used to detect the adipogenic differentiation of the cells.


Assuntos
Adipócitos/citologia , Células da Medula Óssea/citologia , Células-Tronco Mesenquimais/citologia , Técnicas Analíticas Microfluídicas/métodos , Análise de Célula Única/métodos , Adipogenia/fisiologia , Animais , Células Cultivadas , Dispositivos Lab-On-A-Chip , Fenômenos Magnéticos , Imãs , Camundongos , Técnicas Analíticas Microfluídicas/instrumentação , Análise de Célula Única/instrumentação
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