Search

This in vitro study evaluated the effects of the infiltration of F- and Ca2+ ions into human enamel by electrokinetic flow (EKF) on the enamel microhardness and F- content. Sound human enamel ground sections of unerupted third molars were infiltrated with de-ionized water by EKF and with F- ion by EKF respectively. All samples were submitted to two successive transverse acid-etch biopsies (etching times of 30 s and 20 min) to quantify F- ion infiltrated deep into enamel. Remarkably, sound enamel showed a large increase in microhardness (MH) after infiltration of NaF (p < 0.00001) and CaCl2 (p = 0.013) by EKF. Additionally, NaF-EKF increased the remineralization in the lesion body of artificial enamel caries lesions compared to controls (p < 0.01). With the enamel biopsy technique, at both etching times, more F- ions were found in the EKF-treated group than the control group (p << 0.05), and more fluoride was extracted from deeper biopsies in the NaF-EKF group. In conclusion, our results show that EKF treatment is superior in transporting Ca2+ and F− ions into sound enamel when compared to molecular diffusion, enhancing both the mineralization of sound enamel and the remineralization of artificial enamel caries. [ABSTRACT FROM AUTHOR]

Here, we propose a fully-automated platform using a spiral inertial microfluidic device for standardized semen preparation that can process patient-derived semen samples with diverse fluidic conditions without any pre-washing steps. We utilized the multi-dimensional double spiral (MDDS) device to effectively isolate sperm cells from other non-sperm seminal cells (e.g., leukocytes) in the semen sample. The recirculation platform was employed to minimize sample dependency and achieve highly purified and concentrated (up to tenfold) sperm cells in a rapid and fully-automated manner (~ 10 min processing time for 50 mL of diluted semen sample). The clinical (raw) semen samples obtained from healthy donors were directly used without any pre-washing step to evaluate the developed separation platform, which showed excellent performance with ~ 80% of sperm cell recovery, and > 99.95% and > 98% removal of 10-μm beads (a surrogate for leukocytes) from low-viscosity and high-viscosity semen samples, respectively. We expect that the novel platform will be an efficient and automated tool to achieve purified sperm cells directly from raw semen samples for assisted reproductive technologies (ARTs) as an alternative to density centrifugation or swim-up methods, which often suffer from the low recovery of sperm cells and labor-intensive steps. [ABSTRACT FROM AUTHOR]

Chinese hamster ovary (CHO) cells have been the most commonly used mammalian host for large-scale commercial production of therapeutic proteins, such as monoclonal antibodies. Enhancement of productivity of these CHO cells is one of the top priorities in the biopharmaceutical industry to reduce manufacturing cost. Although there are many different methods (e.g. temperature, pH, feed) to improve protein production in CHO cells, the role of physiologically relevant hydrostatic pressure in CHO cell culture has not been reported yet. In this study, four different hydrostatic pressures (0, 30, 60, and 90 mmHg) were applied to batch CHO cells, and their cell growth/metabolism and IgG1 production were examined. Our results indicate that hydrostatic pressure can increase the maximum cell concentration by up to 50%. Moreover, overall IgG1 concentration on Day 5 showed that 30 mmHg pressure can increase IgG1 production by 26%. The percentage of non-disulphide-linked antibody aggregates had no significant change under pressure. Besides, no significant difference was observed between 30 mmHg and no pressure conditions in terms of cell clumping formation. All these findings are important for the optimization of fed-batch or perfusion culture for directing cell growth and improving antibody production. [ABSTRACT FROM AUTHOR]

Background: Emergence of drug-resistant cancer phenotypes is a challenge for anti-cancer therapy. Cancer stem cells are identified as one of the ways by which chemoresistance develops.Method: We investigated the anti-inflammatory combinatorial treatment (DA) of doxorubicin and aspirin using a preclinical microfluidic model on cancer cell lines and patient-derived circulating tumour cell clusters. The model had been previously demonstrated to predict patient overall prognosis.Results: We demonstrated that low-dose aspirin with a sub-optimal dose of doxorubicin for 72 h could generate higher killing efficacy and enhanced apoptosis. Seven days of DA treatment significantly reduced the proportion of cancer stem cells and colony-forming ability. DA treatment delayed the inhibition of interleukin-6 secretion, which is mediated by both COX-dependent and independent pathways. The response of patients varied due to clinical heterogeneity, with 62.5% and 64.7% of samples demonstrating higher killing efficacy or reduction in cancer stem cell (CSC) proportions after DA treatment, respectively. These results highlight the importance of using patient-derived models for drug discovery.Conclusions: This preclinical proof of concept seeks to reduce the onset of CSCs generated post treatment by stressful stimuli. Our study will promote a better understanding of anti-inflammatory treatments for cancer and reduce the risk of relapse in patients. [ABSTRACT FROM AUTHOR]

We report a new technique for sensitive, quantitative and rapid detection of Plasmodium spp.-infected red blood cells (RBCs) by means of magnetic resonance relaxometry (MRR). During the intraerythrocytic cycle, malaria parasites metabolize large amounts of cellular hemoglobin and convert it into hemozoin crystallites. We exploit the relatively large paramagnetic susceptibility of these hemozoin particles, which induce substantial changes in the transverse relaxation rate of proton nuclear magnetic resonance of RBCs, to infer the 'parasite load' in blood. Using an inexpensive benchtop 0.5-Tesla MRR system, we show that with minimal sample preparatory steps and without any chemical or immunolabeling, a parasitemia level of fewer than ten parasites per microliter in a volume below 10 μl of whole blood is detected in a few minutes. We demonstrate this method both for cultured Plasmodium falciparum parasites and in vivo with Plasmodium berghei-infected mice. [ABSTRACT FROM AUTHOR]

The dynamics of DNA molecules in highly confined nanoslits under varying electric fields are studied using dissipative particle dynamics method, and our results show that manipulation of the electrical field can strongly influence DNA mobility. The mobility of DNA μ scales with electric field E as $$ \mu = \mu^{\text{H}} - k_{1} e^{{ - E/E_{c} }} . $$ And the data points for different DNA lengths finally approach each other in strong fields, which suggest that the sensitivity to chain length is almost lost. To explain the unusual field-dependent phenomena, we analyze the time evolution of DNA configurations under different fields. For strong driving potentials when the system is dominated by the electric driving force, the DNA chains are more likely to hold coiled configurations. For weak driving potential when the random diffusion forces dominate, we see frequent dynamic transitions between stretched and coiled configuration, which may increase the drag resistance, therefore reduce the mobility. [ABSTRACT FROM AUTHOR]

Conventional functional electrical stimulation aims to restore functional motor activity of patients with disabilities resulting from spinal cord injury or neurological disorders. However, intervention with functional electrical stimulation in neurological diseases lacks an effective implantable method that suppresses unwanted nerve signals. We have developed an electrochemical method to activate and inhibit a nerve by electrically modulating ion concentrations in situ along the nerve. Using ion-selective membranes to achieve different excitability states of the nerve, we observe either a reduction of the electrical threshold for stimulation by up to approximately 40%, or voluntary, reversible inhibition of nerve signal propagation. This low-threshold electrochemical stimulation method is applicable in current implantable neuroprosthetic devices, whereas the on-demand nerve-blocking mechanism could offer effective clinical intervention in disease states caused by uncontrolled nerve activation, such as epilepsy and chronic pain syndromes. [ABSTRACT FROM AUTHOR]

Here, we report a new method of concentration-enhanced binding kinetics for a rapid immunoassay screening test on a gold surface in a poly(dimethylsiloxane) (PDMS) microfluidic chip format. The use of alkylthiolate self-assembled monolayers on gold surfaces of a PDMS-glass microchip resulted in accelerated binding kinetics at an electrokinetic trapping zone. We used human chorionic gonadotropin (hCG) as a model analyte for a tumor marker to demonstrate the potential ability of dynamic preconcentrating operation in serum using 1D planar gold surface and demonstrated concentration-enhanced binding kinetics by 500-fold. The preconcentration of cy3 labeled streptavidin onto biotinylated Au surface also revealed that the binding kinetics of the protein were linearly proportional to the concentration profile of the preconcentration plug. We showed rapid detection of hCG in the clinical range with a shorten total assay time of 15 min. The enhanced binding kinetics between hCG antigen-antibody via preconcentration showed good feasibility for use in a rapid immunoassay screening test. [ABSTRACT FROM AUTHOR]

When modeling the hydrodynamics of nanofluidic systems, it is often essential to include molecular-level information such as molecular fluctuations. To this effect, we present a mesoscopic approach which combines a fluctuating hydrodynamics formulation with an efficient implementation of Electroosmotic flow (EOF) in the small Debye length limit. The resulting approach, whose major ingredient is Dissipative Particle Dynamics, is sufficiently coarse-grained to allow efficient simulation of the hydrodynamics of micro/nanofluidic devices of sizes that are too large to be simulated by ab initio methods such as Molecular Dynamics. Within our formulation, EOF is efficiently generated using the recently proven similitude between velocity and electric field under appropriate conditions. More specifically, EOF is generated using an effective boundary condition, akin to a moving wall, thus avoiding evaluation of the computationally expensive electrostatic forces. Our method is used for simulating EOFs and DNA molecular sieving in simple and complex two-dimensional (2D) and 3D geometries frequently used in nano-fluidic devices. The numerical data obtained from our model are in very good agreement with theoretical results. [ABSTRACT FROM AUTHOR]

Microfabricated regular sieving structures hold great promise as an alternative to gels to improve the speed and resolution of biomolecule separation. In contrast to disordered porous gel networks, these regular structures also provide well defined environments ideal for the study of molecular dynamics in confining spaces. However, the use of regular sieving structures has, to date, been limited to the separation of long DNA molecules, however separation of smaller, physiologically relevant macromolecules, such as proteins, still remains a challenge. Here we report a microfabricated anisotropic sieving structure consisting of a two-dimensional periodic nanofluidic filter array. The designed structural anisotropy causes different-sized or -charged biomolecules to follow distinct trajectories, leading to efficient separation. Continuous-flow size-based separation of DNA and proteins, as well as electrostatic separation of proteins, was achieved, demonstrating the potential use of this device as a generic molecular sieving structure for an integrated biomolecule sample preparation and analysis system. [ABSTRACT FROM AUTHOR]

Long-term management for leukemia is challenging due to the painful and invasive procedure of bone marrow (BM) biopsy. At present, non-invasive liquid (blood) biopsy is not utilized for leukemia, due to lower counts of leukemia blast cells in the blood. Here, we described a robust system for the simultaneous detection and enrichment of rare blast cells. Enrichment of blast cells was achieved from blood with a one-step microfluidic blast cell biochip (BCB) sorting system, without specific targeting of proteins by antibodies. Non-target cells encountered a differential net force as compared to stiffer blast cells and were removed. The efficiency of the BCB promotes high detection sensitivity (1 in 106 cells) even from patients with minimal residual disease. The procedure was validated using actual blast cells from patients with various types of leukemia. Outcomes were compared to current evaluation standards, such as flow cytometry, using BM aspirates. Blast cell detection efficiency was higher in 55.6% of the patients using the BCB as compared to flow cytometry, despite the lower concentrations of blast cells in liquid biopsy. These studies promote early-stage detection and routine monitoring for minimal residual disease in patients. [ABSTRACT FROM AUTHOR]

Rapid bacterial identification remains a critical challenge in infectious disease diagnostics. We developed a novel molecular approach to detect and identify a wide diversity of bacterial pathogens in a single, simple assay, exploiting the conservation, abundance, and rich phylogenetic content of ribosomal RNA in a rapid fluorescent hybridization assay that requires no amplification or enzymology. Of 117 isolates from 64 species across 4 phyla, this assay identified bacteria with >89% accuracy at the species level and 100% accuracy at the family level, enabling all critical clinical distinctions. In pilot studies on primary clinical specimens, including sputum, blood cultures, and pus, bacteria from 5 different phyla were identified. [ABSTRACT FROM AUTHOR]

Upon Plasmodium falciparum infection of the red blood cells (RBCs), the parasite replicates and consumes haemoglobin resulting in the release of free heme which is rapidly converted to hemozoin crystallites. The bulk magnetic susceptibility of infected RBCs (iRBCs) is changed due to ferric (Fe3+) paramagnetic state in hemozoin crystallites which induce a measurable change in spin-spin relaxation (transverse relaxation) rate in proton nuclear magnetic resonance (NMR) of iRBCs. Earlier, our group reported that this transverse relaxation rate (R2) can be measured by an inexpensive, portable 0.5 Tesla bench top magnetic resonance relaxometry (MRR) system with minimum sample preparation and is able to detect very low levels of parasitemia in both blood cultures as well as animal models. However, it was challenging to diagnose malaria in human blood using MRR, mainly due to the inherent variation of R2 values of clinical blood samples, caused by many physiological and genotypic differences not related to the parasite infection. To resolve the problem of baseline R2 rates, we have developed an improved lysis protocol for removing confounding molecular and cellular background for MRR detection. With this new protocol and by processing larger volume of blood (>1 ml), we are able to reliably detect very low level of parasitemia (representing early stage of infection, ~0.0001%) with a stable baseline and improved sensitivity using the current MRR system. [ABSTRACT FROM AUTHOR]

This corrects the article DOI: 10.1038/srep31850 [ABSTRACT FROM AUTHOR]

Club cells are known to function as regional progenitor cells to repair the bronchiolar epithelium in response to lung damage. By lineage tracing in mice, we have shown recently that club cells also give rise to alveolar type 2 cells (AT2s) and alveolar type 1 cells (AT1s) during the repair of the damaged alveolar epithelium. Here, we show that when highly purified, anatomically and phenotypically confirmed club cells are seeded in 3-dimensional culture either in bulk or individually, they proliferate and differentiate into both AT2- and AT1-like cells and form alveolar-like structures. This differentiation was further confirmed by transcriptomic analysis of freshly isolated club cells and their cultured progeny. Freshly isolated club cells express Sca-1 and integrin α6, markers commonly used to characterize lung stem/progenitor cells. Together, current study for the first time isolated highly purified club cells for in vitro study and demonstrated club cells' capacity to differentiate into alveolar epithelial cells at the single-cell level. [ABSTRACT FROM AUTHOR]

Microfiltration is a ubiquitous and often crucial part of many industrial processes, including biopharmaceutical manufacturing. Yet, all existing filtration systems suffer from the issue of membrane clogging, which fundamentally limits the efficiency and reliability of the filtration process. Herein, we report the development of a membrane-less microfiltration system by massively parallelizing inertial microfluidics to achieve a macroscopic volume processing rates (~ 500 mL/min). We demonstrated the systems engineered for CHO (10-20 μm) and yeast (3-5 μm) cells filtration, which are two main cell types used for large-scale bioreactors. Our proposed system can replace existing filtration membrane and provide passive (no external force fields), continuous filtration, thus eliminating the need for membrane replacement. This platform has the desirable combinations of high throughput, low-cost, and scalability, making it compatible for a myriad of microfiltration applications and industrial purposes. [ABSTRACT FROM AUTHOR]

Plasmodium falciparum malaria parasites invade and remodel human red blood cells (RBCs) by trafficking parasite-synthesized proteins to the RBC surface. While these proteins mediate interactions with host cells that contribute to disease pathogenesis, the infected RBC surface proteome remains poorly characterized. Here we use a novel strategy (I-SELEX) to discover high affinity aptamers that selectively recognize distinct epitopes uniquely present on parasite-infected RBCs. Based on inertial focusing in spiral microfluidic channels, I-SELEX enables stringent partitioning of cells (efficiency ≥ 106) from unbound oligonucleotides at high volume throughput (~2 × 106 cells min−1). Using an RBC model displaying a single, non-native antigen and live malaria parasite-infected RBCs as targets, we establish suitability of this strategy for de novo aptamer selections. We demonstrate recovery of a diverse set of aptamers that recognize distinct, surface-displayed epitopes on parasite-infected RBCs with nanomolar affinity, including an aptamer against the protein responsible for placental sequestration, var2CSA. These findings validate I-SELEX as a broadly applicable aptamer discovery platform that enables identification of new reagents for mapping the parasite-infected RBC surface proteome at higher molecular resolution to potentially contribute to malaria diagnostics, therapeutics and vaccine efforts. [ABSTRACT FROM AUTHOR]

Despite significant advancements over the years, there remains an urgent need for low cost diagnostic approaches that allow for rapid, reliable and sensitive detection of malaria parasites in clinical samples. Our previous work has shown that magnetic resonance relaxometry (MRR) is a potentially highly sensitive tool for malaria diagnosis. A key challenge for making MRR based malaria diagnostics suitable for clinical testing is the fact that MRR baseline fluctuation exists between individuals, making it difficult to detect low level parasitemia. To overcome this problem, it is important to establish the MRR baseline of each individual while having the ability to reliably determine any changes that are caused by the infection of malaria parasite. Here we show that an approach that combines the use of microfluidic cell enrichment with a saponin lysis before MRR detection can overcome these challenges and provide the basis for a highly sensitive and reliable diagnostic approach of malaria parasites. Importantly, as little as 0.0005% of ring stage parasites can be detected reliably, making this ideally suited for the detection of malaria parasites in peripheral blood obtained from patients. The approaches used here are envisaged to provide a new malaria diagnosis solution in the near future. [ABSTRACT FROM AUTHOR]

A correction to the article "Direct seawater desalination by ion concentration polarization" that was published in 2010 issue is presented.