Scalable Parallel Manipulation of Single Cells Using Micronozzle Array Integrated with Bidirectional Electrokinetic Pumps.
TL;DR: This paper reports on the integration of a polydimethylsiloxane (PDMS) micronozzle array and bidirectional electrokinetic pumps driven by DC-biased AC voltages, which is anticipated to be a standard integration method.
Abstract: High throughput reconstruction of in vivo cellular environments allows for efficient investigation of cellular functions. If one-side-open multi-channel microdevices are integrated with micropumps, the devices will achieve higher throughput in the manipulation of single cells while maintaining flexibility and open accessibility. This paper reports on the integration of a polydimethylsiloxane (PDMS) micronozzle array and bidirectional electrokinetic pumps driven by DC-biased AC voltages. Pt/Ti and indium tin oxide (ITO) electrodes were used to study the effect of DC bias and peak-to-peak voltage and electrodes in a low conductivity isotonic solution. The flow was bidirectionally controlled by changing the DC bias. A pump integrated with a micronozzle array was used to transport single HeLa cells into nozzle holes. The application of DC-biased AC voltage (100 kHz, 10 Vpp, and VDC: -4 V) provided a sufficient electroosmotic flow outside the nozzle array. This integration method of nozzle and pumps is anticipated to be a standard integration method. The operating conditions of DC-biased AC electrokinetic pumps in a biological buffer was clarified and found useful for cell manipulation.
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TL;DR: This work discusses the common cell printing strategies and introduces several typical and advanced printing strategies, and discusses the pros and cons of the single- cell strategies and provides a brief outlook for single-cell printing.
Abstract: Single-cell analysis is becoming an indispensable tool in modern biological and medical research. Single-cell isolation is the key step for single-cell analysis. Single-cell printing shows several distinct advantages among the single-cell isolation techniques, such as precise deposition, high encapsulation efficiency, and easy recovery. Therefore, recent developments in single-cell printing have attracted extensive attention. We review herein the recently developed bioprinting strategies with single-cell resolution, with a special focus on inkjet-like single-cell printing. First, we discuss the common cell printing strategies and introduce several typical and advanced printing strategies. Then, we introduce several typical applications based on single-cell printing, from single-cell array screening and mass spectrometry-based single-cell analysis to three-dimensional tissue formation. In the last part, we discuss the pros and cons of the single-cell strategies and provide a brief outlook for single-cell printing.
7 citations
TL;DR: In this paper, a soft charged nanochannel with a dense polyelectrolyte layer (PEL) is considered to be more realistic than a low-density PEL.
Abstract: Space electroosmotic thrusters (EOTs) are theoretically investigated in a soft charged nanochannel with a dense polyelectrolyte layer (PEL), which is considered to be more realistic than a low-density PEL. When the PEL is dense, its permittivity is smaller than the one of the electrolyte solution layer, leading to rearrangement of ions in the channel, which is denoted as the ion partitioning effect. It is noted that fluid viscosity becomes high within the PEL owing to the hydration effect. An analytical solution for electroosmotic velocity through the channel is obtained by utilizing the Debye-Huckel linearization assumption. Based on the fluid motion, thruster performances, including thrust, specific impulse, thrust-to-power ratio, and efficiency, are calculated. The ion partitioning effect leads to enhancement of the thruster velocity, while increase of the dynamic viscosity inside the PEL reduces the flow rate of the fluid. Therefore, these performances are further impacted by the dense soft material, which are discussed in detail. Moreover, changes or improvements of the thruster performances from the dense PEL to the weak PEL are presented and compared, and distributions of various energy items are also provided in this study. There is a good result whereby the increase in electric double layer thickness promotes the development of thruster performances. Ultimately, the simulated EOTs produce thrust of about 0 to 20 μN and achieve thruster efficiency of 90.40%, while maintaining an appropriate thrust-power ratio of about 1.53 mN/W by optimizing all design parameters.
4 citations
TL;DR: The functional, genetic, or compositional heterogeneity of healthy and diseased tissues promotes significant challenges to drug discovery and development as discussed by the authors, which is a challenge for drug development and development.
Abstract: The functional, genetic, or compositional heterogeneity of healthy and diseased tissues promotes significant challenges to drug discovery and development [...]
2 citations
TL;DR: In this article , a 2D-FEM model is proposed to solve the Poisson-Nernst-Planck equation coupled with the Navier-Stokes and continuity equations.
Abstract: Separation and isolation of suspended submicron particles is fundamental to a wide range of applications, including desalination, chemical processing, and medical diagnostics. Ion concentration polarization (ICP), an electrokinetic phenomenon in micro-nano interfaces, has gained attention due to its unique ability to manipulate molecules or particles in suspension and solution. Less well understood, though, is the ability of this phenomenon to generate circulatory fluid flow, and how this enables and enhances continuous particle capture. Here, we perform a comprehensive study of a low-voltage ICP, demonstrating a new electrokinetic method for extracting submicron particles via flow-enhanced particle redirection. To do so, a 2D-FEM model solves the Poisson–Nernst–Planck equation coupled with the Navier–Stokes and continuity equations. Four distinct operational modes (Allowed, Blocked, Captured, and Dodged) were recognized as a function of the particle’s charges and sizes, resulting in the capture or release from ICP-induced vortices, with the critical particle dimensions determined by appropriately tuning inlet flow rates (200–800 [µm/s]) and applied voltages (0–2.5 [V]). It is found that vortices are generated above a non-dimensional ICP-induced velocity of U*=1, which represents an equilibrium between ICP velocity and lateral flow velocity. It was also found that in the case of multi-target separation, the surface charge of the particle, rather than a particle’s size, is the primary determinant of particle trajectory. These findings contribute to a better understanding of ICP-based particle separation and isolation, as well as laying the foundations for the rational design and optimization of ICP-based sorting systems.
2 citations
01 Jan 2021
TL;DR: In this article, the advantages and drawbacks associated with using nanomaterials are presented, as well as the application of different nano-based contrast agents and their application in biomedical imaging.
Abstract: Pre-clinical imaging is a technique that could help in investigating deep inside the rodents to obtain information regarding disease site and drug development process using a non-invasive approach. Diverse FDA approved contrast agents have been implemented since the evolution of these imaging technologies. The current limitations of these contrast agents include faster clearance and photo instability and could be unsuitable for multi-modal and hybrid imaging. These impediments can be overcome with the aid of developing new nanotechnology-based contrast agents. This opens up a new paradigm for researchers to visualize cancer to obtain nanomolecular information. During the past two decades, nano-based contrast agents have revolutionized pre-clinical imaging science, which offers to detect cancers early, rapidly, and effectively. Despite the fact, the concept and technology of imaging are old, the way we look at the disease using nanomaterials in a different perspective. Additionally, the imaging techniques combined with nanotechnology-based contrast agents can be used to investigate the interaction of drugs at a pre-clinical stage and the cellular level. Pre-clinical imaging is performed with two different strategies. The former techniques give anatomical information, which includes computed tomography, magnetic resonance imaging, and ultrasound. While the latter presents molecular information using optical techniques, photon-acoustic imaging, and positron emission tomography. Recent developments in nanotechnology-based contrast agents have opened new avenues to alter and improve the current imaging modalities resulting in hybrid and multi-modal imaging approaches. Here, we intend to provide fundamental knowledge and general considerations of using nanomaterials in pre-clinical imaging modalities. This chapter provides extensive information about the advancements in nanomaterials for pre-clinical imaging applications. In the later part, we discuss the science behind individual nanomaterials with different imaging systems and its improvements in pre-clinical imaging. Also, the advantages and drawbacks associated with nanomaterials are presented. Finally, we discuss the application of different nano-based contrast agents and their application in biomedical imaging.
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TL;DR: It is shown that endothelial cells but not vascular smooth muscle cells release soluble factors that stimulate the self-renewal of neural stem cells, inhibit their differentiation, and enhance their neuron production.
Abstract: Neural stem cells are reported to lie in a vascular niche, but there is no direct evidence for a functional relationship between the stem cells and blood vessel component cells We show that endothelial cells but not vascular smooth muscle cells release soluble factors that stimulate the self-renewal of neural stem cells, inhibit their differentiation, and enhance their neuron production Both embryonic and adult neural stem cells respond, allowing extensive production of both projection neuron and interneuron types in vitro Endothelial coculture stimulates neuroepithelial cell contact, activating Notch and Hes 1 to promote self-renewal These findings identify endothelial cells as a critical component of the neural stem cell niche
1,531 citations
TL;DR: An optical image-driven dielectrophoresis technique that permits high-resolution patterning of electric fields on a photoconductive surface for manipulating single particles and requires 100,000 times less optical intensity than optical tweezers is presented.
Abstract: The ability to manipulate biological cells and micrometre-scale particles plays an important role in many biological and colloidal science applications. However, conventional manipulation techniques--including optical tweezers, electrokinetic forces (electrophoresis, dielectrophoresis, travelling-wave dielectrophoresis), magnetic tweezers, acoustic traps and hydrodynamic flows--cannot achieve high resolution and high throughput at the same time. Optical tweezers offer high resolution for trapping single particles, but have a limited manipulation area owing to tight focusing requirements; on the other hand, electrokinetic forces and other mechanisms provide high throughput, but lack the flexibility or the spatial resolution necessary for controlling individual cells. Here we present an optical image-driven dielectrophoresis technique that permits high-resolution patterning of electric fields on a photoconductive surface for manipulating single particles. It requires 100,000 times less optical intensity than optical tweezers. Using an incoherent light source (a light-emitting diode or a halogen lamp) and a digital micromirror spatial light modulator, we have demonstrated parallel manipulation of 15,000 particle traps on a 1.3 x 1.0 mm2 area. With direct optical imaging control, multiple manipulation functions are combined to achieve complex, multi-step manipulation protocols.
1,380 citations
TL;DR: A review of plasmon-based optical traps can be found in this paper, which summarizes the recent advances in the emerging field and discusses the potential applications to bioscience and quantum optics.
Abstract: Conventional optical tweezers, formed at the diffraction-limited focus of a laser beam, have become a powerful and flexible tool for manipulating micrometre-sized objects. Extending optical trapping down to the nanometre scale would open unprecedented opportunities in many fields of science, where such nano-optical tweezers would allow the ultra-accurate positioning of single nano-objects. Among the possible strategies, the ability of metallic nanostructures to control light at the subwavelength scale can be exploited to engineer such nano-optical traps. This Review summarizes the recent advances in the emerging field of plasmon-based optical trapping and discusses the details of plasmon tweezers along with their potential applications to bioscience and quantum optics.
1,255 citations
TL;DR: A microfluidic device to trap and properly pair thousands of cells, and observed that electrical fusion was more efficient than chemical fusion, with membrane reorganization efficiencies of up to 89%.
Abstract: Cell fusion has been used for many different purposes, including generation of hybridomas and reprogramming of somatic cells. The fusion step is the key event in initiation of these procedures. Standard fusion techniques, however, provide poor and random cell contact, leading to low yields. We present here a microfluidic device to trap and properly pair thousands of cells. Using this device, we paired different cell types, including fibroblasts, mouse embryonic stem cells and myeloma cells, achieving pairing efficiencies up to 70%. The device is compatible with both chemical and electrical fusion protocols. We observed that electrical fusion was more efficient than chemical fusion, with membrane reorganization efficiencies of up to 89%. We achieved greater than 50% properly paired and fused cells over the entire device, fivefold greater than with a commercial electrofusion chamber and observed reprogramming in hybrids between mouse embryonic stem cells and mouse embryonic fibroblasts.
562 citations
TL;DR: Critical selection criteria are included for pumps and valves to aid in determining the pumping mechanism that is most appropriate for a given application and important limitations or incompatibilities are addressed.
Abstract: Micropumping has emerged as a critical research area for many electronics and biological applications. A significant driving force underlying this research has been the integration of pumping mechanisms in micro total analysis systems and other multi-functional analysis techniques. Uses in electronics packaging and micromixing and microdosing systems have also capitalized on novel pumping concepts. The present work builds upon a number of existing reviews of micropumping strategies by focusing on the large body of micropump advances reported in the very recent literature. Critical selection criteria are included for pumps and valves to aid in determining the pumping mechanism that is most appropriate for a given application. Important limitations or incompatibilities are also addressed. Quantitative comparisons are provided in graphical and tabular forms.
467 citations