Generation, control, and application of stable bubbles in a hypersonic acoustic system.

Bubble-based microfluidics has been applied in many fields. However, there remains a need for a facile and flexible method for stable bubble generation and control in a microchannel. This paper reports a hypersonic acoustic system that can generate and release functional stable bubbles in a microchannel in an on-demand manner. It was found that the hypersonic frequency in this system played a vital role in the generation and control of bubbles. Specifically, a nanostructurally enhanced acoustic resonator was used to generate highly localized ultrahigh-frequency acoustic waves that ensured the feasibility and rapidity of bubble generation. Simultaneously, the acoustothermal effect of hypersound was harnessed to effectuate precise control over the bubble size. In addition, high-throughput droplet splitting was performed to confirm the stability of bubbles and their functionality in micromanipulation. The results showed that a mother droplet could be split controllably into a desired number of daughter droplets with specific volume ratios. In summary, the hypersonic acoustic system was demonstrated to be capable of on-demand-generation of stable bubbles in a microfluidic context and thus may extend the bubble-based applications.

Convolutional Neural Network-Driven Impedance Flow Cytometry for Accurate Bacterial Differentiation.

Impedance flow cytometry (IFC) has been demonstrated to be an efficient tool for label-free bacterial investigation to obtain the electrical properties in real time. However, the accurate differentiation of different species of bacteria by IFC technology remains a challenge owing to the insignificant differences in data. Here, we developed a convolutional neural networks (ConvNet) deep learning approach to enhance the accuracy and efficiency of the IFC toward distinguishing various species of bacteria. First, more than 1 million sets of impedance data (comprising 42 characteristic features for each set) of various groups of bacteria were trained by the ConvNet model. To improve the efficiency for data analysis, the Spearman correlation coefficient and the mean decrease accuracy of the random forest algorithm were introduced to eliminate feature interaction and extract the opacity of impedance related to the bacterial wall and membrane structure as the predominant features in bacterial differentiation. Moreover, the 25 optimized features were selected with differentiation accuracies of >96% for three groups of bacteria (bacilli, cocci, and vibrio) and >95% for two species of bacilli (Escherichia coli and Salmonella enteritidis), compared to machine learning algorithms (complex tree, linear discriminant, and K-nearest neighbor algorithms) with a maximum accuracy of 76.4%. Furthermore, bacterial differentiation was achieved on spiked samples of different species with different mixing ratios. The proposed ConvNet deep learning-assisted data analysis method of IFC exhibits advantages in analyzing a huge number of data sets with capacity for extracting predominant features within multicomponent information and will bring about progress and advances in the fields of both biosensing and data analysis.

Pinch-off droplet generator using microscale gigahertz acoustics.

The generation and dispensing of microdroplets is a vital process in various fields such as biomedicine, medical diagnosis and chemistry. However, most methods still require the structures of nozzles or microchannels to assist droplet generation, which leads to limitations on system flexibility and restrictions on the size range of the generated droplets. In this paper, we propose a nozzle-free acoustic-based method for generating droplets using a gigahertz (GHz) bulk acoustic wave (BAW). Unlike most of the acoustofluidic approaches, the proposed method produces the droplet by pinching-off the liquid column generated by the acoustic body force at the oil-water interface. Benefitting from the focused acoustic energy and small footprint of the device, four orders of magnitude (ranging from 2 µm to 1800 µm) of droplet size could be produced by controlling the working time and power of the device. We also demonstrated cell encapsulation in the droplet and a high cell viability was achieved. The proposed acoustic-based droplet generation method exhibits capacity for generating droplets with a wide size range, versatility toward different viscosities, as well as biocompatibility for handling viable samples, which shows potential in miniaturization and scalability.

Dual-functional gold nanorods micro pattern guiding cell alignment and cellular microenvironment monitoring.

Surface topography has become a powerful tool to control cell behaviors, however, it's still difficult to monitor cellular microenvironment changes during topography-induced cell responses. Here, a dual-functional platform integrating cell alignment with extracellular pH (pHe) measurement is proposed. The platform is fabricated by assembling gold nanorods (AuNRs) into micro pattern via wettability difference interface method, which provides topographical cues and surface-enhanced Raman scattering (SERS) effect for cell alignment and biochemical detection respectively. Results demonstrate that contact guidance and cell morphology changes are achieved by the AuNRs micro pattern, and pHe are also obtained by the changes of SERS spectra during cell alignment, where the pHe near cytoplasm is lower than nucleus, revealing the heterogeneity of extracellular microenvironment. Moreover, a correlation between lower extracellular pH and higher cell migration ability is revealed, and AuNRs micro pattern can differentiate cells with different migration ability, which may be an inheritable character during cell division. Furthermore, mesenchymal stem cells response dramatically to AuNRs micro pattern, showing different morphology and increased pHe level, offering the potential of impacting stem cell differentiation. This approach provides a new idea for the research of cell regulation and response mechanism.

A targeted hydrodynamic gold nanorod delivery system based on gigahertz acoustic streaming.

The hydrodynamic method mimics the in vivo environment of the mechanical effect on cell stimulation, which not only modulates cell physiology but also shows excellent intracellular delivery ability. Herein, a hydrodynamic intracellular delivery system based on the gigahertz acoustic streaming (AS) effect is proposed, which presents powerful targeted delivery capabilities with high efficiency and universality. Results indicate that the range of cells with AuNR introduction is related to that of AS, enabling a tunable delivery range due to the adjustability of the AS radius. Moreover, with the assistance of AS, the organelle localization delivery of AuNRs with different modifications is enhanced. AuNRs@RGD is inclined to accumulate in the nucleus, while AuNRs@BSA tend to enter the mitochondria and AuNRs@PEGnK tend to accumulate in the lysosome. Finally, the photothermal effect is proved based on the large quantities of AuNRs introduced via AS. The abundant introduction of AuNRs under the action of AS can achieve rapid cell heating with the irradiation of a 785 nm laser, which has great potential in shortening the treatment cycle of photothermal therapy (PTT). Thereby, an efficient hydrodynamic technology in AuNR introduction based on AS has been demonstrated. The outstanding location delivery and organelle targeting of this method provides a new idea for precise medical treatment.

Manipulation of single cells via a Stereo Acoustic Streaming Tunnel (SteAST).

At the single-cell level, cellular parameters, gene expression and cellular function are assayed on an individual but not population-average basis. Essential to observing and analyzing the heterogeneity and behavior of these cells/clusters is the ability to prepare and manipulate individuals. Here, we demonstrate a versatile microsystem, a stereo acoustic streaming tunnel, which is triggered by ultrahigh-frequency bulk acoustic waves and highly confined by a microchannel. We thoroughly analyze the generation and features of stereo acoustic streaming to develop a virtual tunnel for observation, pretreatment and analysis of cells for different single-cell applications. 3D reconstruction, dissociation of clusters, selective trapping/release, in situ analysis and pairing of single cells with barcode gel beads were demonstrated. To further verify the reliability and robustness of this technology in complex biosamples, the separation of circulating tumor cells from undiluted blood based on properties of both physics and immunity was achieved. With the rich selection of handling modes, the platform has the potential to be a full-process microsystem, from pretreatment to analysis, and used in numerous fields, such as in vitro diagnosis, high-throughput single-cell sequencing and drug development.

Accumulation of synovial fluid CD19+CD24hiCD27+ B cells was associated with bone destruction in rheumatoid arthritis.

Regulatory CD19+CD24hiCD27+ B cells were proved to be numerically decreased and functionally impaired in the peripheral blood (PB) from rheumatoid arthritis (RA), with the potential of converting into osteoclast-priming cells. However, the distribution and function of CD19+CD24hiCD27+ B cells in RA synovial fluid (SF) were unclear. In this study, we investigated whether RA SF CD19+CD24hiCD27+ B cells were increased and associated with bone destruction. We found that the proportion of RA SF CD19+CD24hiCD27+ B cells was increased significantly, and was positively correlated with swollen joint counts, tender joint counts and disease activity. CXCL12, CXCL13, CCL19 contributed to the recruitment of CD19+CD24hiCD27+ B cells in RA SF. Notably, CD19+CD24hiCD27+ B cells in the SF from RA expressed significantly more RANKL compared to OA and that in the PB from RA. Critically, RA CD19+CD24hiCD27+ B cells promoted osteoclast (OC) differentiation in vitro, and the number of OCs was higher in cultures with RA SF CD19+CD24hiCD27+ B cells than in those derived from RA PB. Collectively, these findings revealed the accumulation of CD19+CD24hiCD27+ B cells in SF and their likely contribution to joint destruction in RA. Modulating the status of CD19+CD24hiCD27+ B cells might provide novel therapeutic strategies for RA.

Effects of Rat Anti-mouse Interleukin-6 Receptor Antibody on the Recovery of Cognitive Function in Stroke Mice.

This study aimed to investigate the effects of rat anti-mouse interleukin (IL)-6 receptor antibody (MR16-1) on the recovery of cognitive function in stroke mice. Adult male C57BL/6 mice were subjected to middle cerebral artery occlusion (MCAO). Mice were randomly assigned into three groups: sham group, model group, and MR16-1 group. After the treatment of MR16-1, spatial learning and memory performance of mice were evaluated by the Morris water maze (MWM) and Y-maze tests. Then, brain slices were obtained and infarct volume and neuronal apoptosis were assessed by 2,3,5-triphenyltetrazolium chloride (TTC) staining and Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay, respectively. Protein expression levels of apoptosis-associated proteins and multiple inflammatory cytokines were determined by Western blot analysis. Real-time quantitative PCR (RT-PCR) was used to examine the mRNA levels of various inflammatory cytokines in brain slices and cerebrospinal fluid (CSF). The results showed that MR16-1 improved performances of stroke mice in MWM and Y-maze tests. Moreover, MR16-1 ameliorated MCAO-induced infarct, neuronal apoptosis, and inflammatory response. Furthermore, MR16-1 promoted the expression of Bcl-2 and inhibited the expression of Bax in stroke mice, which revealed the inhibitory effect of MR16-1 on neuronal apoptosis. IL-6 levels in brain and CSF were both decreased by MR16-1 treatment in stroke mice. MR16-1 ameliorated cognitive dysfunction and apoptosis in stroke mice, involving the inhibition of inflammatory response and pro-apoptotic Bax, and the up-regulation of anti-apoptotic Bcl-2. The data supported that MR16-1 might be a potential therapeutic drug for the treatment of stroke.

Contact Engineering of Molybdenum Ditelluride Field Effect Transistors through Rapid Thermal Annealing.

Understanding and engineering the interface between metal and two-dimensional materials are of great importance to the research and development of nanoelectronics. In many cases the interface of metal and 2D materials can dominate the transport behavior of the devices. In this study, we focus on the metal contacts of MoTe2 (molybdenum ditelluride) FETs (field effect transistors) and demonstrate how to use post-annealing treatment to modulate their transport behaviors in a controlled manner. We have also carried out low temperature and transmission electron microscopy studies to understand the mechanisms behind the prominent effect of the annealing process. Changes in transport properties are presumably due to anti-site defects formed at the metal-MoTe2 interface under elevated temperature. The study provides more insights into MoTe2 field effect devices and suggests guidelines for future optimizations.

Rutin Attenuates Oxidative Stress and Proinflammatory Cytokine Level in Adjuvant Induced Rheumatoid Arthritis via Inhibition of NF-κB.

The present study was intended to elucidate the effect of rutin, a flavonoid, on arthritis in complete Freund's adjuvant-induced arthritic rats. The present study showed that more pronounced effect has been observed in the case of 15 mg/kg dose of rutin, with significant reduction in paw diameter together with positive modulation of hematological parameters as compared to 2 other tested doses. A significant upsurge in the level of superoxide dismutase, glutathione peroxidase and glutathione were observed together with decrease in the level of malondialdehyde after treatment with rutin in a dose-dependent manner. Furthermore, the effect of rutin on the tumor necrosis factor-α and interleukin-1ß in arthritic rats showed does-dependent lowering of these cytokines with maximum benefit at 15 mg/kg dose and the level of both NF-κB p65 and NF-κBp65 (Ser536) has been significantly reduced in the presence of rutin. Histopathological examination showed that the inflammatory cells infiltration, synovial hyperplasia, pannus formation and cartilage and bone erosion had considerably improved on administration of rutin. In conclusion, our paper strongly demonstrated the protective effect of rutin against the rheumatoid arthritis involved via suppression of NF-κB p65 protein expression.