| 1. |
- Hou, Zining, et al.
(författare)
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Time lapse investigation of antibiotic susceptibility using a microfluidic linear gradient 3D culture device
- 2014
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Ingår i: Lab on a Chip. - : Royal Society of Chemistry (RSC). - 1473-0197 .- 1473-0189. ; 14:17, s. 3409-3418
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Tidskriftsartikel (refereegranskat)abstract
- This study reports a novel approach to quantitatively investigate the antibacterial effect of antibiotics on bacteria using a three-dimensional microfluidic culture device. In particular, our approach is suitable for studying the pharmacodynamics effects of antibiotics on bacterial cells temporally and with a continuous range of concentrations in a single experiment. The responses of bacterial cells to a linear concentration gradient of antibiotics were observed using time-lapse photography, by encapsulating bacterial cells in an agarose-based gel located in a commercially available microfluidics chamber. This approach generates dynamic information with high resolution, in a single operation, e. g., growth curves and antibiotic pharmacodynamics, in a well-controlled environment. No pre-labelling of the cells is needed and therefore any bacterial sample can be tested in this setup. It also provides static information comparable to that of standard techniques for measuring minimum inhibitory concentration (MIC). Five antibiotics with different mechanisms were analysed against wild-type Escherichia coli, Staphylococcus aureus and Salmonella Typhimurium. The entire process, including data analysis, took 2.5-4 h and from the same analysis, high-resolution growth curves were obtained. As a proof of principle, a pharmacodynamic model of streptomycin against Salmonella Typhimurium was built based on the maximal effect model, which agreed well with the experimental results. Our approach has the potential to be a simple and flexible solution to study responding behaviours of microbial cells under different selection pressures both temporally and in a range of concentrations.
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| 2. |
- Liu, Zhenhua, et al.
(författare)
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A Rapid Prototyping Technique for Microfluidics with High Robustness and Flexibility
- 2016
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Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 7:11
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Tidskriftsartikel (refereegranskat)abstract
- In microfluidic device prototyping, master fabrication by traditional photolithography is expensive and time-consuming, especially when the design requires being repeatedly modified to achieve a satisfactory performance. By introducing a high-performance/cost-ratio laser to the traditional soft lithography, this paper describes a flexible and rapid prototyping technique for microfluidics. An ultraviolet (UV) laser directly writes on the photoresist without a photomask, which is suitable for master fabrication. By eliminating the constraints of fixed patterns in the traditional photomask when the masters are made, this prototyping technique gives designers/researchers the convenience to revise or modify their designs iteratively. A device fabricated by this method is tested for particle separation and demonstrates good properties. This technique provides a flexible and rapid solution to fabricating microfluidic devices for non-professionals at relatively low cost.
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| 3. |
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| 4. |
- Xu, Wenchao, et al.
(författare)
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Viscosity-difference-induced asymmetric selective focusing for large stroke particle separation
- 2016
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Ingår i: Microfluidics and Nanofluidics. - : Springer Science and Business Media LLC. - 1613-4982 .- 1613-4990. ; 20:9
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Tidskriftsartikel (refereegranskat)abstract
- We developed a new approach for particle separation by introducing viscosity difference of the sheath flows to form an asymmetric focusing of sample particle flow. This approach relies on the high-velocity gradient in the asymmetric focusing of the particle flow to generate a lift force, which plays a dominated role in the particle separation. The larger particles migrate away from the original streamline to the side of the higher relative velocity, while the smaller particles remain close to the streamline. Under high-viscosity (glycerol-water solution) and low-viscosity (PBS) sheath flows, a significant large stroke separation between the smaller (1.0 mu m) and larger (9.9 mu m) particles was achieved in a sample microfluidic device. We demonstrate that the flow rate and the viscosity difference of the sheath flows have an impact on the interval distance of the particle separation that affects the collected purity and on the focusing distribution of the smaller particles that affects the collected concentration. The interval distance of 293 mu m (relative to the channel width: 0.281) and the focusing distribution of 112 mu m (relative to the channel width: 0.107) were obtained in the 1042-mu m-width separation area of the device. This separation method proposed in our work can potentially be applied to biological and medical applications due to the wide interval distance and the narrow focusing distribution of the particle separation, by easy manufacturing in a simple device.
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| 5. |
- Zining, Hou, et al.
(författare)
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A microfluidic approach for dynamic investigation of the antibiotic susceptibility of bacteria
- 2013
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Ingår i: MME 2013 24th Micromechanics and Microsystems Europe Conference.
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Konferensbidrag (refereegranskat)abstract
- The possibility to study the effect on cell growth of a chemical is a valued tool for re- searchers in different areas, such as antibiotic resis- tance, cancer research and metabolic pathways. Traditional approaches need long time and no dynamic information is given. Microfluidics offers short diffusion lengths and steeper gradients for studies of antibiotic susceptibility, which could improve throughput greatly. By combining with time-lapse micrography, information on the dynam- ics may provide additional understanding. A micro- fluidic 3D cell culture chip was used to determine the MIC (minimum inhibitory concentration) and the dynamics of sub-MIC of E. coli against ampicillin and spectinomycin. And the same works have been done in Staphylococcus aureus and Salmonella. It is the first time to reveal this dynamic behaviour of bacteria against antibiotics quantitatively in a micro- fludic device. It is anticipated that it could be ex- tended to many other similar investigations in bio- logical and relevant pharmaceutical or clinical applications.
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