| 1. |
- Akbari, Elham, et al.
(författare)
-
SEPARATION OF CLUSTERS OF GROUP A STREPTOCOCCI USING DETERMINISTIC LATERAL DISPLACEMENT
- 2021
-
Ingår i: MicroTAS 2021 - 25th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419031 ; , s. 1201-1202
-
Konferensbidrag (refereegranskat)abstract
- Differences in morphologies of bacteria and bacteria clusters are known to influence their pathogenicity. However, it is difficult to separate cells and cell clusters based on morphology using standard cell biological methods, making studies of the underlying mechanisms difficult. Here we report a simple label-free method for the continuous separation of clusters of group A streptococci, based on cluster size and morphology, using Deterministic Lateral Displacement (DLD). In general, this opens up for the generation of cell populations with heterogenicity in cluster size and physical properties.
|
|
| 2. |
- Akbari, Elham, et al.
(författare)
-
SEPARATION OF SINGLETS AND CLUSTERS OF GROUP A STREPTOCOCCI USING DETERMINISTIC LATERAL DISPLACEMENT AND FILTER SONICATION
- 2022
-
Ingår i: MicroTAS 2022 - 26th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419048 ; , s. 306-307
-
Konferensbidrag (refereegranskat)abstract
- Differences in morphologies of bacteria and bacteria clusters are thought to contribute to their virulence and colonization. However, the conventional standard cell biological methods cannot separate bacteria and bacteria clusters based on their morphologies and sizes, making studies of the underlying mechanisms difficult. Here we report a simple label-free method for the continuous separation of singlets and clusters, of group A streptococci, based on their size and morphology, using Deterministic Lateral Displacement and filter-sonication. In general, this opens up for the generation of cell populations with heterogenicity in cluster size and physical properties.
|
|
| 3. |
- Arellano-Caicedo, Carlos, et al.
(författare)
-
Habitat complexity affects microbial growth in fractal maze
- 2023
-
Ingår i: Current biology : CB. - : Elsevier BV. - 1879-0445 .- 0960-9822. ; 33:8, s. 4-1458
-
Tidskriftsartikel (refereegranskat)abstract
- The great variety of earth's microorganisms and their functions are attributed to the heterogeneity of their habitats, but our understanding of the impact of this heterogeneity on microbes is limited at the microscale. In this study, we tested how a gradient of spatial habitat complexity in the form of fractal mazes influenced the growth, substrate degradation, and interactions of the bacterial strain Pseudomonas putida and the fungal strain Coprinopsis cinerea. These strains responded in opposite ways: complex habitats strongly reduced fungal growth but, in contrast, increased the abundance of bacteria. Fungal hyphae did not reach far into the mazes and forced bacteria to grow in deeper regions. Bacterial substrate degradation strongly increased with habitat complexity, even more than bacterial biomass, up to an optimal depth, while the most remote parts of the mazes showed both decreased biomass and substrate degradation. These results suggest an increase in enzymatic activity in confined spaces, where areas may experience enhanced microbial activity and resource use efficiency. Very remote spaces showing a slower turnover of substrates illustrate a mechanism which may contribute to the long-term storage of organic matter in soils. We demonstrate here that the sole effect of spatial microstructures affects microbial growth and substrate degradation, leading to differences in local microscale spatial availability. These differences might add up to considerable changes in nutrient cycling at the macroscale, such as contributing to soil organic carbon storage.
|
|
| 4. |
- Arellano-Caicedo, Carlos, et al.
(författare)
-
Habitat geometry in artificial microstructure affects bacterial and fungal growth, interactions, and substrate degradation
- 2021
-
Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 4:1
-
Tidskriftsartikel (refereegranskat)abstract
- Microhabitat conditions determine the magnitude and speed of microbial processes but have been challenging to investigate. In this study we used microfluidic devices to determine the effect of the spatial distortion of a pore space on fungal and bacterial growth, interactions, and substrate degradation. The devices contained channels differing in bending angles and order. Sharper angles reduced fungal and bacterial biomass, especially when angles were repeated in the same direction. Substrate degradation was only decreased by sharper angles when fungi and bacteria were grown together. Investigation at the cellular scale suggests that this was caused by fungal habitat modification, since hyphae branched in sharp and repeated turns, blocking the dispersal of bacteria and the substrate. Our results demonstrate how the geometry of microstructures can influence microbial activity. This can be transferable to soil pore spaces, where spatial occlusion and microbial feedback on microstructures is thought to explain organic matter stabilization.
|
|
| 5. |
- Arellano-Caicedo, Carlos, et al.
(författare)
-
Quantification of growth and nutrient consumption of bacterial and fungal cultures in microfluidic microhabitat models
- 2024
-
Ingår i: STAR Protocols. - 2666-1667. ; 5:1
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding microbes in nature requires consideration of their microenvironment. Here, we present a protocol for quantifying biomass and nutrient degradation of bacterial and fungal cultures (Pseudomonas putida and Coprinopsis cinerea, respectively) in microfluidics. We describe steps for mask design and fabrication, master printing, polydimethylsiloxane chip fabrication, and chip inoculation and imaging using fluorescence microscopy. We include procedures for image analysis, plotting, and statistics. For complete details on the use and execution of this protocol, please refer to Arellano-Caicedo et al. (2023).1
|
|
| 6. |
- Beech, Jason P., et al.
(författare)
-
Electrokinetic wall effect mechanisms and applications
- 2020
-
Ingår i: MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - 9781733419017 ; , s. 42-43
-
Konferensbidrag (refereegranskat)abstract
- Under the application of longitudinal electric fields in microchannels, microparticles experience lift forces that push them away from the channel walls and affect their trajectories. At high frequencies (>100KHz) the dielectrophoretic forces dominate and are well understood but at lower frequencies there is little agreement as to the exact nature of the forces, how they are generated and how they vary due to the many different experimental conditions that are used in microfluidics devices. Here we present an experimental study of these mechanisms.
|
|
| 7. |
- Beech, Jason P, et al.
(författare)
-
Using symmetry to control viscoelastic waves in pillar arrays
- 2023
-
Ingår i: RSC Advances. - 2046-2069. ; 13:45, s. 31497-31506
-
Tidskriftsartikel (refereegranskat)abstract
- Solutions of macromolecules exhibit viscoelastic properties and unlike Newtonian fluids, they may break time-reversal symmetry at low Reynolds numbers resulting in elastic turbulence. Furthermore, under some conditions, instead of the chaotic turbulence, the result is large-scale waves in the form of cyclic spatial and temporal concentration variations, as has been shown for macromolecular DNA flowing in microfluidic pillar arrays. We here demonstrate how altering the symmetry of the individual pillars can be used to influence the symmetry of these waves. We control the extent of instabilities in viscoelastic flow by leveraging the effects of the symmetry of the pillars on the waves, demonstrating suppressed viscoelastic fluctuations with relevance for transport and sorting applications, or conversely opening up for enhanced viscoelasticity-mediated mixing. The onset of waves, which changes flow resistance, occurs at different Deborah numbers for flow in different directions through the array of triangular pillars, thus breaking the symmetry of the flow resistance along the device, opening up for using the occurrence of the waves to construct a fluidic diode.
|
|
| 8. |
- Chen, Yang, et al.
(författare)
-
Semiconductor nanowire array for transparent photovoltaic applications
- 2021
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 118:19
-
Tidskriftsartikel (refereegranskat)abstract
- The surface area of a building that could potentially be used for Building Integrated Photovoltaics would increase dramatically with the availability of transparent solar cells that could replace windows. The challenge is to capture energy from outside the visible region (UV or IR) while simultaneously allowing a high-quality observation of the outside world and transmitting sufficient light in the visible region to satisfactorily illuminate the interior of the building. In this paper, we show both computationally and experimentally that InP nanowire arrays can have good transparency in the visible region and high absorption in the near-infrared region. We show experimentally that we can achieve mean transparencies in the visible region of 65% and the radiative limit of more than 10% based on measured absorption and calculated emission. Our results demonstrate that nanowire arrays hold promise as a method to achieve transparent solar cells, which would fulfill the requirements to function as windows. In addition, we show that by optical design and by designing the geometry of nanowire arrays, solar cells can be achieved that absorb/transmit at wavelengths that are not decided by the bandgap of the material and that can be tailored to specific requirements such as colorful windows.
|
|
| 9. |
- Ho, Bao D., et al.
(författare)
-
Cell sorting using electrokinetic deterministic lateral displacement
- 2020
-
Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- We show that by combining deterministic lateral displacement (DLD) with electrokinetics, it is possible to sort cells based on differences in their membrane and/or internal structures. Using heat to deactivate cells, which change their viability and structure, we then demonstrate sorting of a mixture of viable and non-viable cells for two different cell types. For Escherichia coli, the size change due to deactivation is insufficient to allow size-based DLD separation. Our method instead leverages the considerable change in zeta potential to achieve separation at low frequency. Conversely, for Saccharomyces cerevisiae (Baker’s yeast) the heat treatment does not result in any significant change of zeta potential. Instead, we perform the sorting at higher frequency and utilize what we believe is a change in dielectrophoretic mobility for the separation. We expect our work to form a basis for the development of simple, low-cost, continuous label-free methods that can separate cells and bioparticles based on their intrinsic properties.
|
|
| 10. |
- Ho, Bao D., et al.
(författare)
-
Charge-based separation of micro-and nanoparticles
- 2020
-
Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 11:11
-
Tidskriftsartikel (refereegranskat)abstract
- Deterministic Lateral Displacement (DLD) is a label-free particle sorting method that separates by size continuously and with high resolution. By combining DLD with electric fields (eDLD), we show separation of a variety of nano and micro-sized particles primarily by their zeta potential. Zeta potential is an indicator of electrokinetic charge—the charge corresponding to the electric field at the shear plane—an important property of micro-and nanoparticles in colloidal or separation science. We also demonstrate proof of principle of separation of nanoscale liposomes of different lipid compositions, with strong relevance for biomedicine. We perform careful characterization of relevant experimental conditions necessary to obtain adequate sorting of different particle types. By choosing a combination of frequency and amplitude, sorting can be made sensitive to the particle subgroup of interest. The enhanced displacement effect due to electrokinetics is found to be significant at low frequency and for particles with high zeta potential. The effect appears to scale with the square of the voltage, suggesting that it is associated with either non-linear electrokinetics or dielectrophoresis (DEP). However, since we observe large changes in separation behavior over the frequency range at which DEP forces are expected to remain constant, DEP can be ruled out.
|
|
