| 1. |
- Augustsson, Per, et al.
(författare)
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Acoustophoretic microfluidic chip for sequential elution of surface bound molecules from beads or cells
- 2012
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Ingår i: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- An acoustophoresis-based microfluidic flow-chip is presented as a novel platform to facilitate analysis of proteins and peptides loosely bound to the surface of beads or cells. The chip allows for direct removal of the background surrounding the beads or cells, followed by sequential treatment and collection of a sequence of up to five different buffer conditions. During this treatment, the beads/cells are retained in a single flow by acoustic radiation force. Eluted peptides are collected from the outlets and subsequently purified by miniaturized solid-phase extraction and analyzed with matrix assisted laser desorption mass spectrometry. Fundamental parameters such as the system fluidics and dispersion are presented. The device was successfully applied for wash and sequential elution of peptides bound to the surface of microbeads and human spermatozoa, respectively. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4749289]
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| 2. |
- Baldwin, Lydia, et al.
(författare)
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Development of a dual-flow tissue perfusion device for modeling the gastrointestinal tract-brain axis
- 2023
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Ingår i: Biomicrofluidics. - 1932-1058. ; 17:5
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Tidskriftsartikel (refereegranskat)abstract
- Despite the large number of microfluidic devices that have been described over the past decade for the study of tissues and organs, few have become widely adopted. There are many reasons for this lack of adoption, primarily that devices are constructed for a single purpose or because they are highly complex and require relatively expensive investment in facilities and training. Here, we describe a microphysiological system (MPS) that is simple to use and provides fluid channels above and below cells, or tissue biopsies, maintained on a disposable, poly(methyl methacrylate), carrier held between polycarbonate outer plates. All other fittings are standard Luer sizes for ease of adoption. The carrier can be coated with cells on both sides to generate membrane barriers, and the devices can be established in series to allow medium to flow from one cell layer to another. Furthermore, the carrier containing cells can be easily removed after treatment on the device and the cells can be visualized or recovered for additional off-chip analysis. A 0.4 mu m membrane with cell monolayers proved most effective in maintaining separate fluid flows, allowing apical and basal surfaces to be perfused independently. A panel of different cell lines (Caco-2, HT29-MTX-E12, SH-SY5Y, and HUVEC) were successfully maintained in the MPS for up to 7 days, either alone or on devices connected in series. The presence of tight junctions and mucin was expressed as expected by Caco-2 and HT-29-MTX-E12, with Concanavalin A showing uniform staining. Addition of Annexin V and PI showed viability of these cells to be >80% at 7 days. Bacterial extracellular vesicles (BEVs) produced by Bacteroides thetaiotaomicron and labeled with 1,1 '-dioctadecyl-3,3,3 ',3 '-tetramethylindocarbo-cyanine perchlorate (DiD) were used as a model component of the human colonic microbiota and were visualized translocating from an apical surface containing Caco-2 cells to differentiated SH-SY5Y neuronal cells cultured on the basal surface of connected devices. The newly described MPS can be easily adapted, by changing the carrier to maintain spheroids, pieces, or slices of biopsy tissue and joined in series to study a variety of cell and tissue processes. The cell layers can be made more complex through the addition of multiple cell types and/or different patterning of extracellular matrix and the ability to culture cells adjacent to one another to allow study of cell:cell transfer, e.g., passive or active drug transfer, virus or bacterial entry or BEV uptake and transfer.
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| 3. |
- Björk, Sara M., et al.
(författare)
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Metabolite profiling of microfluidic cell culture conditions for droplet based screening
- 2015
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Ingår i: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the impact of droplet culture conditions on cell metabolic state by determining key metabolite concentrations in S. cerevisiae cultures in different microfluidic droplet culture formats. Control of culture conditions is critical for single cell/clone screening in droplets, such as directed evolution of yeast, as cell metabolic state directly affects production yields from cell factories. Here, we analyze glucose, pyruvate, ethanol, and glycerol, central metabolites in yeast glucose dissimilation to establish culture formats for screening of respiring as well as fermenting yeast. Metabolite profiling provides a more nuanced estimate of cell state compared to proliferation studies alone. We show that the choice of droplet incubation format impacts cell proliferation and metabolite production. The standard syringe incubation of droplets exhibited metabolite profiles similar to oxygen limited cultures, whereas the metabolite profiles of cells cultured in the alternative wide tube droplet incubation format resemble those from aerobic culture. Furthermore, we demonstrate retained droplet stability and size in the new better oxygenated droplet incubation format.
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| 4. |
- Fornell, Anna, et al.
(författare)
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An acoustofluidic platform for non-contact trapping of cell-laden hydrogel droplets compatible with optical microscopy
- 2019
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Ingår i: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Production of cell-laden hydrogel droplets as miniaturized niches for 3D cell culture provides a new route for cell-based assays. Such production can be enabled by droplet microfluidics and here we present a droplet trapping system based on bulk acoustic waves for handling hydrogel droplets in a continuous flow format. The droplet trapping system consists of a glass capillary equipped with a small piezoelectric transducer. By applying ultrasound (4 MHz), a localized acoustic standing wave field is generated in the capillary, trapping the droplets in a well-defined cluster above the transducer area. The results show that the droplet cluster can be retained at flow rates of up to 76 mu l/min, corresponding to an average flow speed of 3.2 mm/s. The system allows for important operations such as continuous perfusion and/or addition of chemical reagents to the encapsulated cells with in situ optical access. This feature is demonstrated by performing on-chip staining of the cell nuclei. The key advantages of this trapping method are that it is label-free and gentle and thus well-suited for biological applications. Moreover, the droplets can easily be released on-demand, which facilitates downstream analysis. It is envisioned that the presented droplet trapping system will be a valuable tool for a wide range of multistep assays as well as long-term monitoring of cells encapsulated in gel-based droplets.
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| 5. |
- Fornell, Anna, et al.
(författare)
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An intra-droplet particle switch for droplet microfluidics using bulk acoustic waves
- 2017
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Ingår i: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- To transfer cell- and bead-assays into droplet-based platforms typically requires the use of complex microfluidic circuits, which calls for methods to switch the direction of the encapsulated particles. We present a microfluidic chip where the combination of acoustic manipulation at two different harmonics and a trident-shaped droplet-splitter enables direction-switching of microbeads and yeast cells in droplet microfluidic circuits. At the first harmonic, the encapsulated particles exit the splitter in the center daughter droplets, while at the second harmonic, the particles exit in the side daughter droplets. This method holds promises for droplet-based assays where particle-positioning needs to be selectively controlled.
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| 6. |
- Freitag, C., et al.
(författare)
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Visualizing the entire DNA from a chromosome in a single frame
- 2015
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Ingår i: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- The contiguity and phase of sequence information are intrinsic to obtain complete understanding of the genome and its relationship to phenotype. We report the fabrication and application of a novel nanochannel design that folds megabase lengths of genomic DNA into a systematic back-and-forth meandering path. Such meandering nanochannels enabled us to visualize the complete 5.7 Mbp (1mm) stained DNA length of a Schizosaccharomyces pombe chromosome in a single frame of a CCD. We were able to hold the DNA in situ while implementing partial denaturation to obtain a barcode pattern that we could match to a reference map using the Poland-Scheraga model for DNA melting. The facility to compose such long linear lengths of genomic DNA in one field of view enabled us to directly visualize a repeat motif, count the repeat unit number, and chart its location in the genome by reference to unique barcode motifs found at measurable distances from the repeat. Meandering nanochannel dimensions can easily be tailored to human chromosome scales, which would enable the whole genome to be visualized in seconds. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
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| 7. |
- Gabrielsson, Erik O., 1985-, et al.
(författare)
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Polyphosphonium-Based Ion Bipolar Junction Transistors
- 2014
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Ingår i: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 8:6, s. 064116-
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Tidskriftsartikel (refereegranskat)abstract
- Advancements in the field of electronics during the past few decades have inspired the use of transistors in a diversity of research fields, including biology and medicine. However, signals in living organisms are not only carried by electrons, but also through fluxes of ions and biomolecules. Thus, in order to implement the transistor functionality to control biological signals, devices that can modulate currents of ions and biomolecules, i.e. ionic transistors and diodes, are needed. One successful approach for modulation of ionic currents is to use oppositely charged ion-selective membranes to form so called ion bipolar junction transistors (IBJTs). Unfortunately, overall IBJT device performance has been hindered due to the typical low mobility of ions, large geometries of the ion bipolar junction materials, and the possibility of electric field enhanced (EFE) water dissociation in the junction. Here, we introduce a novel polyphosphonium-based anion-selective material into npn-type IBJTs. The new material does not show EFE water dissociation and therefore allows for a reduction of junction length down to 2 μm, which significantly improves the switching performance of the ion transistor to 2 s. The presented improvement in speed as well the simplified design will be useful for future development of advanced iontronic circuits employing IBJTs, for example addressable drug-delivery devices.
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| 8. |
- Gabrielsson, Erik, et al.
(författare)
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Polyphosphonium-based bipolar membranes for rectification of ionic currents
- 2013
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Ingår i: Biomicrofluidics. - : American Institute of Physics (AIP). - 1932-1058. ; 7:6, s. 064117-
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Tidskriftsartikel (refereegranskat)abstract
- Bipolar membranes (BMs) have interesting applications within the field of bioelectronics, as they may be used to create non-linear ionic components (e. g., ion diodes and transistors), thereby extending the functionality of, otherwise linear, electrophoretic drug delivery devices. However, BM based diodes suffer from a number of limitations, such as narrow voltage operation range and/or high hysteresis. In this work, we circumvent these problems by using a novel polyphosphonium-based BM, which is shown to exhibit improved diode characteristics. We believe that this new type of BM diode will be useful for creating complex addressable ionic circuits for delivery of charged biomolecules.
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| 9. |
- Hammarström, Björn, et al.
(författare)
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Efficient sample preparation in immuno-matrix-assisted laser desorption/ionization mass spectrometry using acoustic trapping
- 2013
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Ingår i: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 7:2
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Tidskriftsartikel (refereegranskat)abstract
- Acoustic trapping of minute bead amounts against fluid flow allows for easy automation of multiple assay steps, using a convenient aspirate/dispense format. Here, a method based on acoustic trapping that allows sample preparation for immuno-matrix-assisted laser desorption/ionization mass spectrometry using only half a million 2.8 mu m antibody covered beads is presented. The acoustic trapping is done in 200 x 2000 mu m2 glass capillaries and provides highly efficient binding and washing conditions, as shown by complete removal of detergents and sample processing times of 5-10 min. The versatility of the method is demonstrated using an antibody against Angiotensin I (Ang I), a peptide hormone involved in hypotension. Using this model system, the acoustic trapping was efficient in enriching Angiotensin at 400 pM spiked in plasma samples. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4798473]
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| 10. |
- Ibis, Fatma, et al.
(författare)
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Nucleation kinetics of calcium oxalate monohydrate as a function of pH, magnesium, and osteopontin concentration quantified with droplet microfluidics
- 2021
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Ingår i: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 15:6
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Tidskriftsartikel (refereegranskat)abstract
- A droplet-based microfluidic platform is presented to study the nucleation kinetics of calcium oxalate monohydrate (COM), the most common constituent of kidney stones, while carefully monitoring the pseudo-polymorphic transitions. The precipitation kinetics of COM is studied as a function of supersaturation and pH as well as in the presence of inhibitors of stone formation, magnesium ions (Mg2+), and osteopontin (OPN). We rationalize the trends observed in the measured nucleation rates leveraging a solution chemistry model validated using isothermal solubility measurements. In equimolar calcium and oxalate ion concentrations with different buffer solutions, dramatically slower kinetics is observed at pH 6.0 compared to pHs 3.6 and 8.6. The addition of both Mg2+ and OPN to the solution slows down kinetics appreciably. Interestingly, complete nucleation inhibition is observed at significantly lower OPN, namely, 3.2 x 10(-8) M, than Mg2+ concentrations, 0.875 x 10(-4) M. The observed inhibition effect of OPN emphasizes the often-overlooked role of macromolecules on COM nucleation due to their low concentration presence in urine. Moreover, analysis of growth rates calculated from observed lag times suggests that inhibition in the presence of Mg2+ cannot be explained solely on altered supersaturation. The presented study highlights the potential of microfluidics in overcoming a major challenge in nephrolithiasis research, the overwhelming physiochemical complexity of urine.
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