| 1. |
- Fornell, Anna, et al.
(författare)
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Acoustic focusing of beads and cells in hydrogel droplets
- 2021
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- The generation of hydrogel droplets using droplet microfluidics has emerged as a powerful tool with many applications in biology and medicine. Here, a microfluidic system to control the position of particles (beads or astrocyte cells) in hydrogel droplets using bulk acoustic standing waves is presented. The chip consisted of a droplet generator and a 380 µm wide acoustic focusing channel. Droplets comprising hydrogel precursor solution (polyethylene glycol tetraacrylate or a combination of polyethylene glycol tetraacrylate and gelatine methacrylate), photoinitiator and particles were generated. The droplets passed along the acoustic focusing channel where a half wavelength acoustic standing wave field was generated, and the particles were focused to the centre line of the droplets (i.e. the pressure nodal line) by the acoustic force. The droplets were cross-linked by exposure to UV-light, freezing the particles in their positions. With the acoustics applied, 89 ± 19% of the particles (polystyrene beads, 10 µm diameter) were positioned in an area ± 10% from the centre line. As proof-of-principle for biological particles, astrocytes were focused in hydrogel droplets using the same principle. The viability of the astrocytes after 7 days in culture was 72 ± 22% when exposed to the acoustic focusing compared with 70 ± 19% for samples not exposed to the acoustic focusing. This technology provides a platform to control the spatial position of bioparticles in hydrogel droplets, and opens up for the generation of more complex biological hydrogel structures.
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| 2. |
- Botte, Ermes, et al.
(författare)
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Size-related variability of oxygen consumption rates in individual human hepatic cells
- 2024
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Ingår i: Lab on a Chip. - : Royal Society of Chemistry. - 1473-0197 .- 1473-0189.
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Tidskriftsartikel (refereegranskat)abstract
- Accurate descriptions of the variability in single-cell oxygen consumption and its size-dependency are key to establishingmore robust tissue models. By combining microfabricated devices with multiparameter identification algorithms, wedemonstrate that single human hepatocytes exhibit an oxygen level-dependent consumption rate and that their maximaloxygen consumption rate is significantly lower than that of typical hepatic cell cultures. Moreover, we found that clusters oftwo or more cells competing for a limited oxygen supply reduced their maximal consumption rate, highlighting their abilityto adapt to local resource availability and the presence of nearby cells. We used our approach to characterize the covarianceof size and oxygen consumption rate within a cell population, showing that size matters, since oxygen metabolism covarieslognormally with cell size. Our study paves the way for linking the metabolic activity of single human hepatocytes to theirtissue- or organ-level metabolism and describing its size-related variability through scaling laws.
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| 3. |
- Cantoni, Federico, et al.
(författare)
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A carrier with an integrated perfusion and heating systems for long-term imaging of microfluidic chips
- 2021
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Konferensbidrag (refereegranskat)abstract
- Microfluidic chips offer many benefits for cell studies, including an accurate spatial and temporal control over the growth conditions1. Despite the large expansion of microfluidics in biological applications2, there have been only a few developments of devices to simplify microfluidic chip handling and imaging. Here, we present a carrier of well-plate format with integrated cell media recirculation and heating systems to provide a stable environment for the cell culture during the imaging outside the incubator. Moreover, the absence of external tubing reduces the risk of contamination and bubble formation during the carrier transfers and reagent injections enabling long-term experiment monitoring. Our system was validated by repeatedly (day 1, 3, 7 and 10) taking the cultured mouse endothelial cells (bEnd.3) out of the incubator for imaging.
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| 4. |
- Cantoni, Federico, et al.
(författare)
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A microfluidic chip carrier including temperature control and perfusion system for long-term cell imaging
- 2021
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Ingår i: HardwareX. - : Elsevier. - 2468-0672. ; 10, s. e00245-
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Tidskriftsartikel (refereegranskat)abstract
- Microfluidic devices are widely used for biomedical applications but there is still a lack of affordable, reliable and user-friendly systems for transferring microfluidic chips from an incubator to a microscope while maintaining physiological conditions when performing microscopy. The presented carrier represents a cost-effective option for sustaining environmental conditions of microfluidic chips in combination with minimizing the device manipulation required for reagent injection, media exchange or sample collection. The carrier, which has the outer dimension of a standard well plate size, contains an integrated perfusion system that can recirculate the media using piezo pumps, operated in either continuous or intermittent modes (50–1000 µl/min). Furthermore, a film resistive heater made from 37 µm-thick copper wires, including temperature feedback control, was used to maintain the microfluidic chip temperature at 37 °C when outside the incubator. The heater characterisation showed a uniform temperature distribution along the chip channel for perfusion flow rates up to 10 µl/min. To demonstrate the feasibility of our platform for long term cell culture monitoring, mouse brain endothelial cells (bEnd.3) were repeatedly monitored for a period of 10 days, demonstrating a system with both the versatility and the potential for long imaging in microphysiological system cell cultures.
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| 5. |
- Cantoni, Federico, et al.
(författare)
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A perfusable multi-hydrogel vasculature on-chip engineered by 2-photon 3D printing and scaffold molding to improve microfabrication fidelity in hydrogels
- 2024
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Ingår i: Advanced Materials Technologies. - : John Wiley & Sons. - 2365-709X. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- Engineering vasculature networks in physiologically relevant hydrogelsrepresents a challenge in terms of both fabrication, due to the cell–bioinkinteractions, as well as the subsequent hydrogel-device interfacing. Here, anew cell-friendly fabrication strategy is presented to realize perfusablemulti-hydrogel vasculature models supporting co-culture integrated in amicrofluidic chip. The system comprises two different hydrogels to specificallysupport the growth and proliferation of two different cell types selected for thevessel model. First, the channels are printed in a gelatin-based ink bytwo-photon polymerization (2PP) inside the microfluidic device. Then, ahuman lung fibroblast-laden fibrin hydrogel is injected to surround the printednetwork. Finally, human endothelial cells are seeded inside the printedchannels. The printing parameters and fibrin composition are optimized toreduce hydrogel swelling and ensure a stable model that can be perfused withcell media. Fabricating the hydrogel structure in two steps ensures that nocells are exposed to cytotoxic fabrication processes, while still obtaining highfidelity printing. In this work, the possibility to guide the endothelial cellinvasion through the 3D printed scaffold and perfusion of the co-culturemodel for 10 days is successfully demonstrated on a custom-made perfusionsystem.
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| 6. |
- Cantoni, Federico
(författare)
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Fabrication advances of microvasculature models on-chip
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Despite the technological advances of the last decades, drug development remains a lengthy and costly process with uncertainties still associated with the poor predictive power of the in vitro and animal models. To address this limitation, microphysiological systems have been introduced in an attempt to increase the biological relevance of in vitro devices. One of the current challenges in MPS is the integration of a vasculature network to sustain 3D cultures to closely mimic human physiology. This thesis proposed a new strategy to recreate a more representative vasculature system directly on-chip. As a first step, the 2-photon polymerization was investigated as a 3D printing technique to recreate structures with cell-relevant feature size and resolution. Subsequently, the 2-photon polymerization 3D printing was combined with micromolding to recreate a multi-hydrogel vasculature network integrated on-chip for cell culture. The synergy of the two methods ensured the generation of a high-fidelity multi-hydrogel scaffold for cell co-culture. To preserve the delicate cell culture while still ensuring the sample manipulation for monitoring and analysis, a customized microphysiological system carrier with an integrated heating and perfusion system was also developed. Finally, the possibility of tuning the properties of the 3D-printed hydrogel by controlling the printing parameters was investigated to guide glioblastoma cells to a vascularized compartment. Overall, the thesis not only demonstrated the fabrication versatility of 2 photon polymerization for a vasculature model directly on-chip but also showed the benefits in integrating microphysiological systems on a carrier.
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| 7. |
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| 8. |
- Fornell, Anna, et al.
(författare)
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Acoustic focusing of microparticles in two-phase systems - Towards cell enrichment or medium exchange in droplets
- 2015
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Ingår i: MicroTAS 2015 - 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - : Chemical and Biological Microsystems Society. - 9780979806483 ; , s. 1026-1028
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Konferensbidrag (refereegranskat)abstract
- We present a method to first laterally position microparticles inside droplets by acoustic forces and then split the droplet into three daughter droplets to achieve a 2+fold enrichment of microparticles inside the center droplet. We show that acoustic forces can be applied to both manipulate polystyrene beads (5 μm) and red blood cells inside droplets. The presented technology opens up for development of droplet operations used for medium exchange and particle concentration in droplet-based cell assays.
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| 9. |
- Fornell, Anna, et al.
(författare)
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Controlled Lateral Positioning of Microparticles Inside Droplets Using Acoustophoresis
- 2015
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 87:20, s. 10521-10526
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we utilize bulk acoustic waves to control the position of micropartides inside droplets in two-phase microfluidic systems and demonstrate a method to enrich the micropartides. In droplet microfluidics, different unit operations are combined and integrated on-chip to miniaturize complex biochemical assays. We present a droplet unit operation capable of controlling the position of micropartides during a trident shaped droplet split. An acoustic standing wave field is generated in the microchannel, and the acoustic forces direct the encapsulated micropartides to the center of the droplets. The method is generic, requires no labeling of the micropartides, and is operated in a noncontact fashion. It was possible to achieve 2+-fold enrichment of polystyrene beads (5 mu m in diameter) in the center daughter droplet with an average recovery of 89% of the beads. Red blood cells were also successfully manipulated inside droplets. These results show the possibility to use acoustophoresis in two-phase systems to enrich micropartides and open up the possibility for new droplet-based assays that are not performed today.
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| 10. |
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