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1.
Micromachines (Basel) ; 10(10)2019 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-31561484

RESUMO

In this research, we aimed to count the ratio of the number of motile to immotile sperm for patients with infertility problems based on a low-sperm-concentration examination. The microfluidic system consists of two series of applications: The conventional separation of motile sperm and the proposed inductance (L), capacitance (C), and resistance (R) or LCR impedance sperm counter. In the experiment, 96% of motile sperm were isolated from nonmotile sperm in the first part and transported to the second part to count and calculate real-time sperm concentration. A pair of microelectrodes composed of thin metal film were integrated between microchannels, resulting in a peak signal for LCR single-cell detection, as well as the estimated total sperm concentration. A minimum of 10 µL of the sperm sample was completely analyzed with an accuracy of 94.8% compared with the standard computer-assisted semen analysis (CASA) method. This method could be applied for low-cost sperm separation and counting in the future.

2.
Spectrochim Acta A Mol Biomol Spectrosc ; 204: 670-676, 2018 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-29982158

RESUMO

This work demonstrates a novel compact spectrophotometer, "Mini-spectrophotometer", designed for plasma glucose detection. Unlike conventional spectrophotometer, a light source of the mini spectrophotometer is replaced by a light-emitting diode (LED), and a fabricated polymer-based microwell is used as a cuvette. To validate the downsizing spectrophotometer prototype, the efficiency and reliability for glucose determination are investigated. Using a certain light intensified from LED, the within-run precision of mini-spectrophotometer is found to be 3.9-8.4% while the between-run precision is 6.7-10.8%. The linearity for the quantification of glucose was up to 500 mg dL-1 and the recovery 99.1 ±â€¯3.4% is obtained. The sensitive and selective detection of glucose has been observed; with limit of detection (LOD) of 13.5 mg dL-1 and limit of quantification (LOQ) of 46.2 mg dL-1, respectively. Hemoglobin and triglyceride at high concentration slightly interferes with the proposed instrument. From comparative studies, there are no significant differences between the glucose concentration measured by mini-spectrophotometer and Shimadzu (r2 = 0.9862) or CECIL spectrophotometer (r2 = 0.9853). Using Passing-Bablok regression analysis, the results obtained from mini-spectrophotometer are in close agreement with the two conventional spectrophotometers. Furthermore, using microwell, the sample volume and reagent used in the process can be reduced. The in-house developed mini-spectrophotometer is capable of detecting plasma glucose while maintaining a compact system, demonstrating the potential of high performance, cost-effective, and portable spectrophotometer for clinical chemistry analysis in small routine, research, and teaching medical laboratory technologist.


Assuntos
Glicemia/análise , Miniaturização/instrumentação , Espectrofotometria/instrumentação , Desenho de Equipamento , Humanos , Limite de Detecção , Modelos Lineares , Reprodutibilidade dos Testes
3.
PLoS One ; 13(5): e0196383, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29746494

RESUMO

Morphological transformations in primitive organisms have long been observed; however, its biomechanical roles are largely unexplored. In this study, we investigate the structural advantages of dimorphism in Arthrospira platensis, a filamentous multicellular cyanobacterium. We report that helical trichomes, the default shape, have a higher persistence length (Lp), indicating a higher resistance to bending or a large value of flexural rigidity (kf), the product of the local cell stiffness (E) and the moment of inertia of the trichomes' cross-section (I). Through Atomic Force Microscopy (AFM), we determined that the E of straight and helical trichomes were the same. In contrast, our computational model shows that I is greatly dependent on helical radii, implying that trichome morphology is the major contributor to kf variation. According to our estimation, increasing the helical radii alone can increase kf by 2 orders of magnitude. We also observe that straight trichomes have improved gliding ability, due to its structure and lower kf. Our study shows that dimorphism provides mechanical adjustability to the organism and may allow it to thrive in different environmental conditions. The higher kf provides helical trichomes a better nutrient uptake through advection in aquatic environments. On the other hand, the lower kf improves the gliding ability of straight trichomes in aquatic environments, enabling it to chemotactically relocate to more favorable territories when it encounters certain environmental stresses. When more optimal conditions are encountered, straight trichomes can revert to their original helical form. Our study is one of the first to highlight the biomechanical role of an overall-shape transformation in cyanobacteria.


Assuntos
Forma Celular/fisiologia , Spirulina/citologia , Spirulina/metabolismo , Fenômenos Bioquímicos , Transporte Biológico/fisiologia , Fenômenos Biomecânicos , Biofísica , Simulação por Computador , Cianobactérias/citologia , Cianobactérias/metabolismo , Cianobactérias/fisiologia , Tricomas/fisiologia
4.
Biomicrofluidics ; 8(3): 034108, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-25379069

RESUMO

A simple microwell-based microfluidic chip for microalgal cells trapping was fabricated. An electrostaticcell trapping mechanism, enabled by a positively charged glass surface, was used. The chip was capable of capturing multiple algal cell types. In the case of filamentous Spirulina platensis, we observed single filament occupancy of up to ∼30% available wells, as high as some previously proposed methods. Captured filaments were not of any preferential size, suggesting well randomized cell trapping. It was found that the electrostatic attraction did not affect the cell growth. Total replacement of liquid inside the wells could be achieved by pumping new solutions via the inlet, making single cell experiments in controlled chemical conditions possible. After the top layer of the chip was removed, cells in the wells could be simply transferred using a micropipette, turning the chip into a platform for strain selection.

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