Gludmckenna0658

We report on a unique microfluidic device that can enrich nanoparticles in a continuous flow by railing them along activated tracks (electrodes). This was achieved based on dielectrophoretic force and electrohydrodynamic drag (electrothermal rolls and AC electroosmosis) in both low and high conductive media. The results have implication for the isolation of high quality and pure nanoparticles such as exosomes from biofluids for applications in cancer diagnosis and prognosis.Recently, the study of communication in an 'Astrocyte Network' has been suggested to be of equal importance to that of the traditional 'Neural Network'. In this paper, for the first time, we use nanosecond laser stimulation to stimulate the central cell in an organized grid network of connected human astrocytes in order to observe calcium wave propagation at the single-cell level. We show that the calcium waves indeed propagate from the central astrocyte to the outer periphery of the organized astrocyte network. We observe also, like astrocytes in standard in vitro petri dishes, that the calcium wave propagates through specific connections to the outer periphery of cells rather than in a uniform radial manner predicted by mathematical theory. The results show that such a platform provides an excellent environment to perform repeatable, controlled studies of calcium wave signal propagation through an organized grid network of human astrocytes at single-cell resolution.Directing the fate of human mesenchymal stem/stromal cells (hMSCs) toward bone formation using mechanical strain is a promising approach in regenerative medicine related to bone diseases. Numerous studies have evaluated the effects of vibration or cyclic tensile strain on MSCs towards developing a mechanically-based method for stimulating differentiation. Here, we study the differentiation of hMSCs cultured on elastic polydimethylsiloxane (PDMS) membrane, which is magnetically actuated to induce periodically varying strain. The strain distribution across the membrane was calculated by finite-element modeling and demonstrates three main areas of different strain amplitudes. The strain effect on the hMSCs was evaluated by measuring the mineralization of differentiated hMSCs using Alizarin S red stain. The results indicate a strain-dependent differentiation of hMSCs, where the highest region of strain on the membrane resulted in the most accelerated differentiation. Osteogenic differentiation was achieved as early as two weeks, which is significantly sooner than control hMSCs treated with osteogenic media alone.Electroporation is a well-established technique used to stimulate cells, enhancing membrane permeability. Although the biological phenomena occurring after the poration process have been widely studied, the physical mechanisms of pore formation are not clearly understood. In this work we investigated by means of molecular dynamics simulations the kinetics of pore formation, linking the different stages of poration to specific arrangements of lipid membrane domains.Clinical Relevance-The approach followed in this study aims to shed light on the molecular mechanisms at the basis of the electroporation technique, nowadays used to enhance the entrance of poorly permeant anticancer drugs into tumor cells, for gene electrotransfer and all the other applications exploiting the modulation of cell membrane properties.Enrichment and separation of Micro/Nano-scale specimens are fundamental requirements in biomedical researches. In this paper, we demonstrated a simple and efficient microfluidic chip for the continuous enrichment and separation of nanoscale polystyrene particles using the acoustic streaming induced by gigahertz(GHz) bulk acoustic waves(BAW). The bulk acoustic resonator released ultrahigh frequency (2GHz) acoustic waves into the fluid and triggered the acoustic streaming. The nanoparticles were continuous concentrated and segregated by the combination action of the viscosity force and the acoustic radiation force. The separation of 300 and 100 nm particles was achieved with the high purity (92.4%). These data contribute proof-in-principle that acoustic streaming is a label-free strategy that can be used to enrich and separate nanoscale specimens with high efficiency.Organ-on-a-chip has the potential to replace preclinical trials which have been problematic for decades due to unaffordable cost and time. The performance of in vitro tumor-on-a-chip depends on how accurately the system represents analogous tumor-microenvironment (TME) and TME associated phenomena. In this study, we have focused on angiogenesis, one of the most significant features of TME for tumor growth and metastasis. Angiogenesis in TME is triggered through cascaded interactions among TME associated neighboring cells including immune cells, tumor cells, and fibroblast cells [1]. Therefore, temporally-controlled TME-on-a-chip is desired for an accurate representation of angiogenesis. However, conventional microfluidic devices cannot temporarily manipulate the condition of interacting cells and secreted signal molecules. Here, we proposed a hydrogel-based variable TME-on-a-chip with diffusion switch channels. The channels between hydrogel walls enable temporal diffusion control by controlling inflow. The diffusion control was observed in diffusion experiment with a fluorescent dye. Furthermore, experiment of HUVEC's migration toward diffused VEGF also confirmed that TME-on-a-chip is capable of reproducing an angiogenic switch triggering through temporal diffusion control. Due to a simple fabrication procedure, the design of the microfluidic device can be easily modified to represent more complex variable TME models.Single-cell dielectrophoretic movement and dielectrophoretic deformation of monocyte cells were interrogated applying 20 Vpp, 50 kHz to 1 MHz signal in the 3D carbon electrode array. Heterogeneity of the monocyte population is shown in terms of the crossover frequencies, translational movement, and deformation index of the cells. The results presented that crossover range for monocytes was 100 kHz - 200 kHz, the translational movement of the cells was rapidly altered when the initial positions of the cells were in the negative dielectrophoretic region. Finally, the deformation index of the monocyte population varied from 0.5 to 1.5.Type 1 diabetic patients characteristically exhibit a loss of insulin production, leading to chronic hyperglycemia and related complications. Herein we describe the design, synthesis and screening of novel oligopeptides for their potential to enhance the secretion of insulin from human pancreatic islets. The investigation of these compounds, based off the patented INGAP-PP sequence, aims to identify the peptide features key to maximizing insulin secretion.Clinical Relevance - This report describes the relative efficacy of selected novel compounds for potential Type 1 Diabetes Therapy. Tested on live human pancreatic islets, the compounds are evaluated for their enhancing/inhibitory effect on the secretion of insulin. These studies pave the way for future targeted drug therapies.The Refractive Index (RI) is an important parameter of characterizing optical properties of particles. In a dual-beam optical trap, two counter-propagating laser beams are used to trap micro-particles suspended in an aqueous medium. When a ray of light passes from one medium of lower RI (e.g. aqueous suspension medium) to another medium of higher RI (e.g. suspended particle), its momentum changes which exerts a proportional trapping force on the surface of the particle. Thus, accurate knowledge of RI of the particles and the surrounding medium is needed to determine the behavior of particles in an optical trap. The RI of micro-sized beads can be experimentally measured using traditional optical methods such as absorption microscopy. We developed an alternative theoretical method to estimate the RI of trapped particles based on non-contact optical trapping experimental outcomes. In our study, a theoretical model was formulated based on the experimentally measured minimum trapping powers for polystyrene and polyethylene beads using a dual-beam optical setup. The tendencies of trapping power-RI curves predicted by our model agreed very well with those measured experimentally. Our technique provides an alternative approach to determining the RI of a certain micro-size particle regardless of its size or density. Our method is especially advantageous over traditional methods to determine RI of biological particles which exhibit significant variations based on physiological and environmental conditions.This is a proof-of-concept study for the development of a field-deployable and low-cost PCR thermocycler (FLC-PCR) to perform Polymerase Chain Reaction (PCR) for the rapid detection of environmental E. coli. Four efficient (77.1 W) peltier modules are used as the central temperature control unit. One 250 W silicone heating pad is used for the heating lid. The PID (proportional-integral-derivative) control algorithm for the thermocycles is implemented by a low-cost 8-bit, 16 MHz microcontroller (ATMEGA328P-PU). ybbW and uidA genes from specific E. coli colonies were used as amplicons for the PCR reactions that were carried out by a commercial PCR machine (Bio-Rad) and our FLC-PCR thermocycler. The heating and cooling speeds averaged 1.11 ± 0.33°C/s which is on a par with the commercial bench-top PCR thermocycler and the efficiency of the heating lid outperformed the Bio-Rad PCR thermocycler. The overall cost of the system is lower than $200 which is more than ten times lower than commercially available units. The heating block can be customized to accommodate different PCR tubes and even microfluidic chambers. 5-aza-CdR An 8000 W portable power generator will be used as the power supply for field studies.Hydroxyapatite is the inorganic component of human bones. To be used for bone replacements, hydroxyapatite can be synthesized or extracted from natural components. In this work we present the hydroxyapatite extraction from fish scales of the same Orechromis family (Tilapia) but from two different species usually consumed in Mexico and in Spain. Our results indicate, for both species, that it is possible to obtain hydroxyapatite, and moreover, that this biomaterial is enriched with magnesium for the Mexican Oreochromis hunteri, and with aluminum for the Spanish Oreochromis niloticus.In-vitro transfection of cells by electroporation is a widely used approach in cell biology and medicine. The transfection method is highly dependent on the cell culture's electrical resistance, which is strongly determined by differences in the membranes, but also on the morphology of the electrodes. Microneedle (MN)-based electrodes have been used to concentrate the electrical field during electroporation, and therefore maximize its effect on cell membrane permeability. So far, the methods used for the fabrication of MN electrodes have been relatively limited with respect to the needle design. In this work, we provide a method to fabricate MNs using 3D printing, which is a technology that provides a high degree of flexibility with respect to geometry and dimensions. Pyramidal-shaped MN designs were fabricated and tested on HCT116 cancer cells. Customization of the tips of the pyramids permits tailoring of the electrical field in the vicinity of the cell membranes. The fabricated device enables low-voltage (2 V) electroporation, eliminating the need for the use of specialized chemical buffers.