1,721,228 research outputs found
Design of a microfluidic strategy for trapping and screening single cells
No full textTraditionally, in vitro investigations on biology and physiology of cells rely on averaging the responses eliciting from heterogeneous cell populations, thus being unsuitable for assessing individual cell behaviors in response to external stimulations. In the last years, great interest has thus been focused on single cell analysis and screening, which represents a promising tool aiming at pursuing the direct and deterministic control over cause-effect relationships guiding cell behavior. In this regard, a high-throughput microfluidic platform for trapping and culturing adherent single cells was presented. A single cell trapping mechanism was implemented based on dynamic variation of fluidic resistances. A round-shaped culture chamber (Φ = 250 μm, h = 25 μm) was conceived presenting two connections with a main fluidic path: (i) an upper wide opening, and (ii) a bottom trapping junction which modulates the hydraulic resistance. Starting from eight different layouts, the chamber geometry was computationally optimized for maximizing the single cell trapping efficacy and then integrated in a polydimethylsiloxane (PDMS) microfluidic device. The final platform consists in (i) 288 chambers for trapping single cells organized in six culture units, independently addressable through the lines of (ii) a chaotic-mixer based serial dilution generator (SDG), designed for creating spatio-temporally controlled patterns of both soluble factors and non-diffusive particles. The device was experimentally validated by trapping polystyrene microspheres, featuring diameters comparable to cell size (Φ = 10 μm)
Experimental characterization of a method to reversibly bond microfluidic devices through magnetic forces
No full textAbstrac
Dispositivo microfluidico e relativo metodo per la generazione e/o la coltivazione e/o la maturazione di costrutti cellulari e/o tissutali tridimensionali
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A microfluidic platform for the rapid establishment of defined cell co-cultures using chaotic mixing.
No full textA Reliable Reversible Bonding Method to Perfuse Microfluidic Devices
No full textMicrofl uidic devices made of poly(dimethylsiloxane) (PDMS) are suitable for cell culture applications, mainly due to both the advantageous volume and surface properties of the material itself. Bulk properties include optical transparency, gas permeability, and ease of fabrication, to name a few. On the other hand, silanol groups (SiOH) present on the surface can be easily activated through air/oxygen plasma treatments, and used to permanently bond to other materials, like silicon, glass or PDMS. The importance of a standard sealing method with no need of additional gluing materials is crucial for microfl uidic applications, where micrometer sized channels and chambers are involved. Despite the reliability of the plasma treatment to permanently seal microfl uidic devices, reversible-bonding methods are sometimes desirable e.g., high magnifi cation microscopy, sample retrieval, and multiple usages of valuable substrates. For this purpose, common techniques rely either on weakening the plasma treatment (partial treatment, only involving one of the surfaces of interest) or on increasing the self-sealing properties of PDMS (by adjusting the ratio of pre-polymer and curing agent). However, the adhesion strength of these methods is low, thus making them suitable only for static or quasi-static conditions. Whenever there is the requirement for continuous perfusion, other techniques are needed. Here, we describe a PDMS microfl uidic device for long term culture of cells, which can be reversibly sealed to different fl at substrates. The hydraulic tightness is guaranteed through magnetic forces, being the substrate interposed between a permanent magnet and the microfl uidic device, locally enriched with ferromagnetic material. In particular, neuronal networks were grown within the device, reversibly coupled to a fl at Microelectrode Array (MEA). Thus, the proposed approach allows to combine the advantageous features of microfl uidics and the multiple use of commercial MEA substrates. Indeed, it allows for electrophysiological investigations in highly controlled microenvironments
High-throughput microfluidic platform for 3D cultures of mesenchymal stem cells
No full textThe design of innovative tools for generating physiologically relevant three-dimensional (3D) in vitro models has been recently recognized as a fundamental step to study cell responses and long-term tissue functionalities thanks to its ability to recapitulate the complexity and the dimensional scale of the cellular microenvironment, while directly integrating high-throughput and automatic screening capabilities. This chapter addresses the development of a poly(dimethylsiloxane)-based microfluidic platform to (1) generate and culture 3D cellular microaggregates under continuous flow perfusion while (2) conditioning them with different combinations/concentrations of soluble factors (i.e., growth factors, morphogens or drug molecules), in a high-throughput fashion. The proposed microfluidic system thus represents a promising tool for establishing innovative high-throughput models for drug screening, investigation of tissues morphogenesis, and optimization of tissue engineering protocols
VA-086 methacrylate gelatine photopolymerizable hydrogels: A parametric study for highly biocompatible 3D cell embedding
Full text linkThe ability to replicate in vitro the native extracellular matrix (ECM) features and to control the three-dimensional (3D) cell organization plays a fundamental role in obtaining functional engineered bioconstructs. In tissue engineering (TE) applications, hydrogels have been successfully implied as biomatrices for 3D cell embedding, exhibiting high similarities to the natural ECM and holding easily tunable mechanical properties. In the present study, we characterized a promising photocrosslinking process to generate cell-laden methacrylate gelatin (GelMA) hydrogels in the presence of VA-086 photoinitiator using a ultraviolet LED source. We investigated the influence of prepolymer concentration and light irradiance on mechanical and biomimetic properties of resulting hydrogels. In details, the increasing of gelatin concentration resulted in enhanced rheological properties and shorter polymerization time. We then defined and validated a reliable photopolymerization protocol for cell embedding (1.5% VA-086, LED 2 mW/cm2) within GelMA hydrogels, which demonstrated to support bone marrow stromal cells viability when cultured up to 7 days. Moreover, we showed how different mechanical properties, derived from different crosslinking parameters, strongly influence cell behavior. In conclusion, this protocol can be considered a versatile tool to obtain biocompatible cell-laden hydrogels with properties easily adaptable for different TE applications
Towards modeling limb development: high-throughput microfluidic platform for culturing mesenchymal stromal cell perfused micromasses
No full textA new microfluidic platform for the highly reproducible preparation of non-viral gene delivery complexes
Full text linkTransfection describes the delivery of exogenous nucleic acids (NAs) to cells utilizing non-viral means. In the last few decades, scientists have been doing their utmost to design ever more effective transfection reagents. These are eventually mixed with NAs to give rise to gene delivery complexes, which must undergo characterization, testing, and further refinement through the sequential reiteration of these steps. Unfortunately, although microfluidics offers distinct advantages over the canonical approaches to preparing particles, the systems available do not address the most frequent and practical quest for the simultaneous generation of multiple polymer-to-NA ratios (N/Ps). Herein, we developed a user-friendly microfluidic cartridge to repeatably prepare non-viral gene delivery particles and screen across a range of seven N/Ps at once or significant volumes of polyplexes at a given N/P. The microchip is equipped with a chaotic serial dilution generator for the automatic linear dilution of the polymer to the downstream area, which encompasses the NA divider to dispense equal amounts of DNA to the mixing area, enabling the formation of particles at seven N/Ps eventually collected in individual built-in tanks. This is the first example of a stand-alone microfluidic cartridge for the fast and repeatable preparation of non-viral gene delivery complexes at different N/Ps and their storage
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