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1.
Artigo em Inglês | MEDLINE | ID: mdl-32129059

RESUMO

Electrodynamic systems for bioanalytical applications constantly encounter biofouling issues due to electrical-field-induced nonspecific bio-adsorption occurring on electrode surfaces. To minimize this issue, surface modification using anti-biofouling and conductive materials is necessary to not only protect the electrode surface from nonspecific bio-adsorption, but also maintain desired electrodynamic properties for electrode operation. The homogeneity and stability of the coating plays a critical role in providing effective passivation, and the anti-biofouling ability of the layer can be determined by the coating lifetime and zwitterionic degree. In this study, we designed and prepared a conductive, zwitterionic, and self-doped sulfonated polyaniline (SPANI) coating on Au electrode surfaces to fulfill the aforementioned three criteria, including anti-biofouling, conductive, and long life-time. The zwitterionic coating was functionalized with cysteamine (HS-CH2CH2-NH2) by electrochemical polymerization of aniline and a post-polymerization treatment with fuming sulfuric acid. We also found that the SPANI-coated electrodes exhibited an excellent anti-biofouling ability in dielectrophoresis (DEP) capturing-and-releasing processes, with a residual mass below 1.44%, whereas electrodes modified with poly(ethylene glycol) (PEG) depicted a residual mass of 14.3%. A three-cycle DEP test showed that the standard deviation (SD) of surface contamination on the electrode coated with SPANI and PEG was 22.47 and 208.99 counts, respectively. Even under more than 1hour continuous operation, the SPANI-5s electrode still provides stable anti-biofouling ability as low average residual mass (1.62%). Besides, the capturing rate of the SPANI-modified electrodes was five times higher than that observed for the PEG-coated electrodes, indicating a better conductance of the SPANI films as compared to the PEG films for electrodynamic operation. This study demonstrates that electrodynamic systems with zwitterionic SPANI coated on open electrode surfaces show decent conductivity and excellent anti-biofouling properties.

2.
J Hazard Mater ; 389: 121821, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-31879116

RESUMO

We have prepared copper nanoclusters (Cu NCs) in the presence of bovine serum albumin (BSA) and 1,3-propanedithiol (PDT). The PDT/BSA-Cu NCs possess great activities against different types of bacteria, including non-multidrug-resistant bacteria (Escherichia coli, Salmonella Enteritidis, Pseudomonas aeruginosa, and Staphylococcus aureus) and multidrug-resistant bacteria (methicillin-resistant S. aureus). Their minimal inhibitory concentration (MIC) values are at least 242-fold and 10-fold lower than that of the free PDT and BSA-Cu NCs, respectively. The PDT/BSA-Cu NCs are strongly bound to the bacterial membrane, in which they induce the generation of ascorbyl (Asc) and perhydroxyl (HOO) radicals that result in disruption of their membrane integrity. At a concentration of 100-fold higher than their MIC for Escherichia coli, the PDT/BSA-Cu NCs exhibit negligible cytotoxicity towards the tested mammalian cells and show insignificant hemolysis. We have further demonstrated that low-cost PDT/BSA-Cu NCs-coated carbon fiber fabrics (CFFs) are effective against antibacterial growth, showing their great potential for antifouling applications.

3.
Adv Exp Med Biol ; 1146: 79-103, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31612455

RESUMO

The last 20 years have seen the blooming of microfluidics technologies applied to biological sciences. Microfluidics provides effective tools for biological analysis, allowing the experimentalists to extend their playground to single cells and single molecules, with high throughput and resolution which were inconceivable few decades ago. In particular, microfluidic devices are profoundly changing the conventional way of studying the cell motility and cell migratory dynamics. In this chapter we will furnish a comprehensive view of the advancements made in the research domain of confinement-induced cell migration, thanks to the use of microfluidic devices. The chapter is subdivided in three parts. Each section will be addressing one of the fundamental questions that the microfluidic technology is contributing to unravel: (i) where cell migration takes place, (ii) why cells migrate and, (iii) how the cells migrate. The first introductory part is devoted to a thumbnail, and partially historical, description of microfluidics and its impact in biological sciences. Stress will be put on two aspects of the devices fabrication process, which are crucial for biological applications: materials used and coating methods. The second paragraph concerns the cell migration induced by environmental cues: chemical, leading to chemotaxis, mechanical, at the basis of mechanotaxis, and electrical, which induces electrotaxis. Each of them will be addressed separately, highlighting the fundamental role of microfluidics in providing the well-controlled experimental conditions where cell migration can be induced, investigated and ultimately understood. The third part of the chapter is entirely dedicated to how the cells move in confined environments. Invadosomes (the joint name for podosomes and invadopodia) are cell protrusion that contribute actively to cell migration or invasion. The formation of invadosomes under confinement is a research topic that only recently has caught the attention of the scientific community: microfluidic design is helping shaping the future direction of this emerging field of research.


Assuntos
Movimento Celular , Microfluídica , Podossomos , Animais , Quimiotaxia , Humanos , Dispositivos Lab-On-A-Chip , Microfluídica/instrumentação , Podossomos/metabolismo , Pesquisa/tendências
4.
Biosens Bioelectron ; 133: 215-222, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30951981

RESUMO

Early diagnosis of bacterial infections is crucial to improving survival rates by enabling treatment with appropriate antibiotics within the first few hours of infection. This paper presents a highly sensitive amperometric biosensor for the detection of several pathogenic bacterial cells in blood plasma around 30 min. The proposed device is based on an electropolymerized self-assembled layer on gold nanoparticles operated in a portable nano-sieving microfluidic system (NS-MFS). The redox-active gold nanoparticles (raGNPs) enhanced the electrical conductivity and provided a greater number of electrochemically active molecules for sensing, while improving resistance to the fouling of sensors by oxidation products in blood plasma. The detection limit of the device has been shown to reach 10 CFU/mL for Pseudomonas aeruginosa and Staphylococcus aureus spiked in plasma. The dynamic range of the sensing system falls between 10 and 105 CFU/mL in a buffer solution by cyclic voltammetry (CV) measurements. The results demonstrated that the raGNPs/NS-MFS can successful detect P. aeruginosa and S. aureus in human plasma, and is very useful for the diagnosis of bacteremia from clinical samples.


Assuntos
Bacteriemia/diagnóstico , Técnicas Biossensoriais , Técnicas Eletroquímicas , Staphylococcus aureus/isolamento & purificação , Bacteriemia/microbiologia , Ouro/química , Humanos , Limite de Detecção , Nanopartículas Metálicas/química , Microfluídica/métodos , Oxirredução
5.
Mikrochim Acta ; 186(3): 166, 2019 02 09.
Artigo em Inglês | MEDLINE | ID: mdl-30739206

RESUMO

Stable and low-cost carbon dots (C-dots) were prepared from polyethylenimine (PEI) by a hydrothermal method. It is found that the fluorescence of the C-dots (best measured at excitation/emission wavelengths of 365/473 nm) is quenched by selective oxidation of surface PEI by periodate but recovers in the presence of uric acid (UA). It is assumed that this is due to the selective reduction of the nitrone groups to hydroxylamine groups by UA. The findings were used to design a fluorometric method for determination of UA that has a 2.3 nM detection limit. This is lower than that of reported fluorometric and enzymatic assays. The performance of the method has been validated by determination of UA in samples of human saliva. It is found that the results agree well with those obtained by a commercial UA assay. Graphical abstract Schematic presentation of the polyethylenimine (PEI) carbon nanodots (C-dots) as a fluorescent probe for uric acid. Their fluorescence is quenched by periodate (IO4-) due to oxidative formation of nitrone groups, an subsequently restored due to reduction by uric acid (UA).


Assuntos
Fluorometria/métodos , Pontos Quânticos/química , Ácido Úrico/análise , Carbono , Fluorescência , Humanos , Limite de Detecção , Nanoestruturas , Nitrogênio , Saliva/química
6.
Cancers (Basel) ; 11(1)2019 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-30626171

RESUMO

Colorectal cancer (CRC) is the second most common cause of cancer-related death worldwide. Detecting and enumerating circulating tumor cells (CTCs) in patients with colorectal cancer emerged as an important prognostic tool which provides a direct estimate of metastatic potential. Improving the turnaround time and decreasing sample volume is critical for incorporating this liquid biopsy tool into routine practice. The objective of the current study was to validate the clinical feasibility of a self-assembled cell array (SACA) chip, a CTC counting platform with less than 4 h turnaround time, in patients with newly diagnosed colorectal cancers. In total, 179 patients with newly diagnosed colorectal cancers from a single institute were enrolled. Epithelial cell adhesion molecule positive (EpCAM(+)), cluster of differentiation 45 negative (CD45(-)) cells were isolated and enumerated from 2 mL of peripheral vein blood (PB) and inferior mesenteric vein blood (IMV) samples obtained during surgery. We found that the CTC count in PB but not IMV correlates with disease stages. Neoadjuvant chemotherapy did not lead to decreased CTC count in both types of blood samples. With cutoffs of four CTCs per 2 mL of blood, and serum carcinoembryonic antigen (CEA) level of 5 ng/mL, patients with non-metastatic disease were more likely to experience recurrence if they had high PB CTC count and high serum CEA concentration (odds ratio, 8.9). Our study demonstrates the feasibility of enumerating CTCs with a SACA chip in patients with colorectal cancer.

7.
Micromachines (Basel) ; 9(5)2018 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-30424161

RESUMO

Transmembrane pressure across the glomerular filter barrier may underlie renal failure. However, studies of renal failure have been difficult owing to a lack of in vitro models to capture the transmembrane pressure in a controlled approach. Here we report a microfluidic platform of podocyte culture to investigate transmembrane pressure induced glomerular leakage. Podocytes, the glomerular epithelial cells essential for filtration function, were cultivated on a porous membrane supplied with transmembrane pressure ΔP. An anodic aluminum oxide membrane with collagen coating was used as the porous membrane, and the filtration function was evaluated using dextrans of different sizes. The results show that dextran in 20 kDa and 70 kDa can penetrate the podocyte membrane, whereas dextran in 500 kDa was blocked until ΔP ≥ 60 mmHg, which resembles the filtration function when ΔP was in the range of a healthy kidney (ΔP < 60 mmHg) as well as the hypertension-induced glomerular leakage (ΔP ≥ 60 mmHg). Additionally, analysis showed that synaptopodin and actin were also downregulated when ΔP > 30 mmHg, indicating that the dysfunction of renal filtration is correlated with the reduction of synaptopodin expression and disorganized actin cytoskeleton. Taking together, our microfluidic platform enables the investigation of transmembrane pressure in glomerular filter membrane, with potential implications for drug development in the future.

8.
Int J Mol Sci ; 19(10)2018 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-30322072

RESUMO

The investigation of human disease mechanisms is difficult due to the heterogeneity in gene expression and the physiological state of cells in a given population. In comparison to bulk cell measurements, single-cell measurement technologies can provide a better understanding of the interactions among molecules, organelles, cells, and the microenvironment, which can aid in the development of therapeutics and diagnostic tools. In recent years, single-cell technologies have become increasingly robust and accessible, although limitations exist. In this review, we describe the recent advances in single-cell technologies and their applications in single-cell manipulation, diagnosis, and therapeutics development.


Assuntos
Técnicas Analíticas Microfluídicas/tendências , Análise de Célula Única/métodos , Humanos , Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas/instrumentação , Análise de Célula Única/instrumentação , Análise de Célula Única/tendências
9.
Sensors (Basel) ; 18(9)2018 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-30223459

RESUMO

Scanning electron microscopy has been developed for topographic analysis at the nanometer scale. Herein, we present a silicon p-n diode with multi-annular configuration to detect backscattering electrons (BSE) in a homemade desktop scanning electron microscope (SEM). The multi-annular configuration enables the enhancement of the topography contrast of 82.11 nA/µm as compared with the commercial multi-fan-shaped BSE detector of 40.08 nA/µm. Additionally, we integrated it with lateral p-n junction processing and aluminum grid structure to increase the sensitivity and efficiency of the multi-annular BSE detector that gives higher sensitivity of atomic number contrast and better surface topography contrast of BSE images for low-energy detection. The responsivity data also shows that MA-AL and MA p-n detectors have higher gain value than the MA detector does. The standard deviation of measurements is no higher than 1%. These results verify that MA p-n and MA-AL detectors are stable and can function well in SEM for low-energy applications. It is demonstrated that the multi-annular (MA) detectors are well suited for imaging in SEM systems.

10.
ACS Appl Mater Interfaces ; 10(36): 30163-30171, 2018 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-30118196

RESUMO

Closed-loop artificial pancreas systems have recently been proposed as a solution for treating stage I diabetes by reproducing the function of the pancreas. However, there are many unresolved issues associated with their development, including monitoring and controlling oxygen, immune responses, and the optimization of glucose, all of which need to be monitored and controlled to produce an efficient and viable artificial organ that can become integrated in the patient and maintain homeostasis. This research focused on monitoring the oxygen concentration, specifically achieving this kinetically as the oxygen gradient in an artificial pancreas made of alginate spheres containing islet cells. Functional nanoparticles (NPs) for measuring the oxygen gradient in different hydrogel cellular environments using fluorescence-based (F) microscopy were developed and tested. By the ester bond, a linker Pluronic F127 was conjugated with a carboxylic acid-modified polystyrene NP (510 nm). A hydrophilic/hydrophobic interaction between the commercially available oxygen-sensitive fluorophore and F127 results in fluorescence-based nano-oxygen particles (FNOPs). The in-house synthesized FNOP was calibrated inside electrosprayed alginate-filled hydrogels and demonstrated a good broad dynamic range (2.73-22.23) mg/L as well as a resolution of -0.01 mg/L with an accuracy of ±4%. The calibrated FNOP was utilized for continuous measuring of the oxygen concentration gradient for cell lines RIN-m5F/HeLa for more than 5 days in alginate hydrogel spheres in vitro.


Assuntos
Fenômenos Fisiológicos Celulares , Técnicas Citológicas/métodos , Oxigênio/química , Fluorescência , Humanos , Hidrogéis/química , Microscopia de Fluorescência , Pâncreas Artificial
11.
Sci Rep ; 8(1): 8503, 2018 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-29844339

RESUMO

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

12.
Small ; 14(24): e1704439, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29770576

RESUMO

The Zn2+ stored in the secretory vesicles of glutamatergic neurons is coreleased with glutamate upon stimulation, resulting in the elevation of extracellular Zn2+ concentration (CZn2+ex). This elevation of CZn2+ex regulates the neurotransmission and facilitates the fibrilization of amyloid-ß (Aß). However, the exact CZn2+ex surrounding neurons under (patho)physiological conditions is not clear and the connection between CZn2+ex and the Aß fibrilization remains obscure. Here, a silicon nanowire field-effect transistor (SiNW-FET) with the Zn2+ -sensitive fluorophore, FluoZin-3 (FZ-3), to quantify the CZn2+ex in real time is modified. This FZ-3/SiNW-FET device has a dissociation constant of ≈12 × 10-9 m against Zn2+ . By placing a coverslip seeded with cultured embryonic cortical neurons atop an FZ-3/SiNW-FET, the CZn2+ex elevated to ≈110 × 10-9 m upon stimulation with α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). Blockers against the AMPA receptor or exocytosis greatly suppress this elevation, indicating that the Zn2+ stored in the synaptic vesicles is the major source responsible for this elevation of CZn2+ex. In addition, a SiNW-FET modified with Aß could bind Zn2+ with a dissociation constant of ≈633 × 10-9 m and respond to the Zn2+ released from AMPA-stimulated neurons. Therefore, the CZn2+ex can reach a level high enough to bind Aß and the Zn2+ homeostasis can be a therapeutic strategy to prevent neurodegeneration.


Assuntos
Peptídeos beta-Amiloides/metabolismo , Espaço Extracelular/química , Nanofios/química , Neurônios/metabolismo , Transistores Eletrônicos , Zinco/farmacologia , Animais , Feminino , Íons , Neurônios/efeitos dos fármacos , Neurotransmissores/metabolismo , Ratos Sprague-Dawley , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/farmacologia
13.
Biomicrofluidics ; 12(1): 011502, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29430272

RESUMO

In recent years, Surface Enhanced Raman Scattering (SERS) has been widely applied to many different areas, including chemical analysis, biomolecule detection, bioagent diagnostics, DNA sequence, and environmental monitor, due to its capabilities of unlabeled fingerprint identification, high sensitivity, and rapid detection. In biomicrofluidic systems, it is also very powerful to integrate SERS based devices with specified micro-fluid flow fields to further focusing/enhancing/multiplexing SERS signals through molecule registration, concentration/accumulation, and allocation. In this review, after a brief introduction of the mechanism of SERS detection on proteins, we will first focus on the effectiveness of different nanostructures for SERS enhancement and light-to-heat conversion in trace protein analysis. Various protein molecule accumulation schemes by either (bio-)chemical or physical ways, such as immuno, electrochemical, Tip-enhanced Raman spectroscopy, and magnetic, will then be reviewed for further SERS signal amplification. The analytical and repeatability/stability issues of SERS detection on proteins will also be brought up for possible solutions. Then, the comparison about various ways employing microfluidic systems to register, concentrate, and enhance the signals of SERS and reduce the background noise by active or passive means to manipulate SERS nanostructures and protein molecules will be elaborated. Finally, we will carry on the discussion on the challenges and opportunities by introducing SERS into biomicrofluidic systems and their potential solutions.

14.
Sci Rep ; 7(1): 11385, 2017 09 12.
Artigo em Inglês | MEDLINE | ID: mdl-28900219

RESUMO

The conventional techniques to detect circulating tumour cells (CTCs) are lengthy and the use of centrifugal forces in this technique may cause cell mortality. As the number of CTCs in patients is quite low, the present study aims towards a gentler diagnostic procedure so as not to lose too many CTCs during the sample preparation process. Hence, a Three-Dimensional Microwell dialysis (3D-µDialysis) chip was designed in this study to perform gentle fluorescence-removal process by using dialysis-type flow processes without centrifuging. This leads to a minimum manual handling of CTCs obtained in our study without any contamination. In addition, a rapid staining process which necessitates only about half the time of conventional techniques (35 minutes instead of 90 minutes) is being illustrated by the employment of dialysis process (by dynamically removing water and waste at once) instead of only static diffusion (by statically removing only waste by diffusion). Staining efficiency of our technique is improved over conventional staining because of the flow rate in 3D-µDialysis staining. Moreover, the staining process has been validated with clinical whole blood samples from three TNM stage IV colon cancer patients. The current technique may be termed as "miniature rapid staining and dialysing system".


Assuntos
Dispositivos Lab-On-A-Chip , Microdiálise/métodos , Técnicas Analíticas Microfluídicas , Células Neoplásicas Circulantes/metabolismo , Células Neoplásicas Circulantes/patologia , Linhagem Celular Tumoral , Desenho de Equipamento , Humanos , Microdiálise/instrumentação , Coloração e Rotulagem
15.
J Vis Exp ; (126)2017 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-28809821

RESUMO

Artificial guidance for cellular alignment is a hot topic in the field of tissue engineering. Most of the previous research has investigated single strain-induced cellular alignment on a cell-laden hydrogel by using complex experimental processes and mass controlling systems, which are usually associated with contamination issues. Thus, in this article, we propose a simple approach to building a gradient static strain using a fluidic chip with a plastic PDMS cover and a UV transparent glass substrate for the stimulation of cellular behavior in a 3D hydrogel. Overloading photo-patternable cell prepolymer in the fluidic chamber can generate a convex curved PDMS membrane on the cover. After UV crosslinking, through a concentric circular micropattern under the curved PDMS membrane, and buffer washing, a microenvironment for investigating cell behaviors under a variety of gradient strains is self-established in a single fluidic chip, without external instruments. NIH3T3 cells were demonstrated after observing the change in the cellular alignment trend under geometry guidance, in cooperation with strain stimulation, which varied from 15 - 65% on hydrogels. After a 3-day incubation, the hydrogel geometry dominated the cell alignment under low compressive strain, where cells aligned along the hydrogel elongation direction under high compressive strain. Between these, the cells showed random alignment due to the dissipation of the radical guidance of hydrogel elongation and the geometry guidance of the patterned hydrogel.


Assuntos
Técnicas de Cultura de Células/instrumentação , Técnicas de Cultura de Células/métodos , Hidrogéis , Dispositivos Lab-On-A-Chip , Animais , Camundongos , Células NIH 3T3 , Engenharia Tecidual , Raios Ultravioleta
16.
Sci Rep ; 7(1): 8363, 2017 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-28827637

RESUMO

Proteins belonging to the toll-like receptor (TLR) family, particularly TLR2, are the major components of innate immunity against Leptospira infection. The ligands for TLR2 harbor several conserved patterns such as lipidation molecules, leucine-rich repeat (LRR) domains, TLR2 binding motifs, and TLR2 binding structure. In Leptospira, LipL32 interacts with TLR2 on human kidney cells concomitantly stimulating inflammatory responses. However, the binding mechanism of LipL32 to TLR2 is unknown. The computational prediction suggests that ß1ß2, loop-α3-loop, and α4 domains of LipL32 play vital roles in LipL32-TLR2 complex formation. To test these predictions, protein truncation experiments revealed that LipL32ΔNß1ß2 significantly decreased the affinity to TLR2 while LipL32ΔCα4 slightly reduced it. Interestingly, LipL32ΔCenα3 retained affinity to TLR2 in the absence of Ca2+ ions, indicating that Cenα3 play a role preventing the interaction between LipL32 and TLR2. Furthermore, the critical residues of LipL32 involved in interacting with TLR2 suggested that V35S, L36S and L263S variants significantly decreased the affinity to TLR2. The results further confirm that LipL32 interacts with TLR2 through Nß1ß2 and Cα4 domains of LipL32 as well as LipL32-TLR2 complex formation results from hydrophobic interactions. This study provides a detailed mechanism of the interaction between LipL32 and TLR2 and the residues involved in complex formation.


Assuntos
Proteínas da Membrana Bacteriana Externa/metabolismo , Leptospira/imunologia , Lipoproteínas/metabolismo , Receptor 2 Toll-Like/metabolismo , Proteínas da Membrana Bacteriana Externa/química , Proteínas da Membrana Bacteriana Externa/genética , Humanos , Interações Hidrofóbicas e Hidrofílicas , Lipoproteínas/química , Lipoproteínas/genética , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Ligação Proteica , Deleção de Sequência , Receptor 2 Toll-Like/química
17.
ACS Sens ; 2(1): 69-79, 2017 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-28722429

RESUMO

The concentration gradient of K+ across the cell membrane of a neuron determines its resting potential and cell excitability. During neurotransmission, the efflux of K+ from the cell via various channels will not only decrease the intracellular K+ content but also elevate the extracellular K+ concentration. However, it is not clear to what extent this change could be. In this study, we developed a multiple-parallel-connected silicon nanowire field-effect transistor (SiNW-FET) modified with K+-specific DNA-aptamers (aptamer/SiNW-FET) for the real-time detection of the K+ efflux from cultured cortical neurons. The aptamer/SiNW-FET showed an association constant of (2.18 ± 0.44) × 106 M-1 against K+ and an either less or negligible response to other alkali metal ions. The α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) stimulation induced an outward current and hyperpolarized the membrane potential in a whole-cell patched neuron under a Na+/K+-free buffer. When neurons were placed atop the aptamer/SiNW-FET in a Na+/K+-free buffer, AMPA (13 µM) stimulation elevated the extracellular K+ concentration to ∼800 nM, which is greatly reduced by 6,7-dinitroquinoxaline-2,3-dione, an AMPA receptor antagonist. The EC50 of AMPA in elevating the extracellular K+ concentration was 10.3 µM. By stimulating the neurons with AMPA under a normal physiological buffer, the K+ concentration in the isolated cytosolic fraction was decreased by 75%. These experiments demonstrate that the aptamer/SiNW-FET is sensitive for detecting cations and the K+ concentrations inside and outside the neurons could be greatly changed to modulate the neuron excitability.

19.
Analyst ; 142(6): 938-944, 2017 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-28220153

RESUMO

In this paper, we propose a microfluidic device capable of generating a retarding flow field for the sorting and separation of human motile sperm in a high-throughput manner. The proposed sorting/separation process begins with a rapid flow field in a straight-flow zone to carry sperm into a sorting zone to maintain the sperm's mobility. The sorting zone consists of a diffuser-type sperm sorter to differentiate sperm with different motilities based on the flowing upstream nature of human sperm in a retarding flow field. The dead sperm will then be separated from the live ones by passing through a dumbbell flow field to the outlet for disposal. The proposed flowing upstream sperm sorter (FUSS) is designed to imitate the selection mechanism found in the female body when sperm swim into the uterus. The experimental results demonstrate the utility of this device with regard to throughput (approximately 200 000 sperm per minute and a maximum of 200 million cells per mL), efficiency (90% of selected sperm are mobile), and the ability to select sperm with high motility (∼20% of sperm with a velocity exceeding 120 µm s-1). The proposed device is suitable for intrauterine insemination as well as in vitro fertilization thanks to the highly efficient sorting process not interfering with the natural function and energy resource of human sperm.


Assuntos
Separação Celular , Dispositivos Lab-On-A-Chip , Análise do Sêmen , Espermatozoides/citologia , Humanos , Masculino , Motilidade Espermática
20.
Sci Rep ; 6: 38171, 2016 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-27910861

RESUMO

Here, we discuss the development of a paper-based diagnostic device that is inexpensive, portable, easy-to-use, robust, and capable of running simultaneous tests to monitor a relevant inflammatory protein for clinical diagnoses i.e. C-reactive protein (CRP). In this study, we first attempted to make a paper-based diagnostic device via the wax printing method, a process that was used in previous studies. This device has two distinct advantages: 1) reduced manufacturing and assay costs and operation duration via using wax printing method to define hydrophobic boundaries (for fluidic devices or general POC devices); and, 2) the hydrophilicity of filter paper, which is used to purify and chromatographically correct interference caused by whole blood components with a tiny amount of blood sample (only 5 µL). Diagnosis was based on serum stain length retained inside the paper channels of our device. This is a balanced function between surface tension and chromatographic force following immune reactions (CRP assays) with a paper-embedded biomarker.

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