Automatic microdispenser-integrated multiplex enzyme-linked immunosorbent assay device with autonomously driven centrifugal microfluidic system

In this study, we established the control and design theory of an autonomously driven dispenser at a steady rotation speed and proposed a dispenser-integrated multiplex enzyme-linked immunosorbent assay (ELISA) device. In establishing the theory of the dispenser, we estimated the flow rate in the dispenser and the applied pressure onto the passive valves, so that the suitable burst pressure of the valves and flow rate could be designed. The dispenser-integrated multiplex ELISA device has the potential to perform flow control for executing an ELISA of 6 samples/standards per chip or 18 samples/standards per compact disk by just steadily rotating a chip. In the immunoassay evaluation of the device using mouse IgG detection, it was confirmed that the device could assay 5 μL of several standards in just 30 min without nonspecific reactions, and although this system has a high limit of detection (LOD, 63.4-164 pg mL-1) it is equal to that of manual assay with a titer plate. The device can be fabricated by transferring the microchannel pattern from a mold without complex assembly or alignment, and it can control the liquid operation by just steadily rotating. Thus, the device system developed will contribute to reducing the cost of fabricating chips and control equipment for ELISA systems. Consequently, a compact, portable, and low-cost ELISA system for point-of-care testing is expected to be realized.

The impact of rare cancer and early-line treatments on the benefit of comprehensive genome profiling-based precision oncology

BACKGROUND

Comprehensive genome profiling (CGP) serves as a guide for suitable genomically matched therapies for patients with cancer. However, little is known about the impact of the timing and types of cancer on the therapeutic benefit of CGP.

MATERIALS AND METHODS

A single hospital-based pan-cancer prospective study (TOP-GEAR; UMIN000011141) was conducted to examine the benefit of CGP with respect to the timing and types of cancer. Patients with advanced solid tumors (>30 types) who either progressed with or without standard treatments were genotyped using a single CGP test. The subjects were followed up for a median duration of 590 days to examine therapeutic response, using progression-free survival (PFS), PFS ratio, and factors associated with therapeutic response.

RESULTS

Among the 507 patients, 62 (12.2%) received matched therapies with an overall response rate (ORR) of 32.3%. The PFS ratios (≥1.3) were observed in 46.3% (19/41) of the evaluated patients. The proportion of subjects receiving such therapies in the rare cancer cohort was lower than that in the non-rare cancer cohort (9.6% and 17.4%, respectively; P = 0.010). However, ORR of the rare cancer patients was higher than that in the non-rare cancer cohort (43.8% and 20.0%, respectively; P = 0.046). Moreover, ORR of matched therapies in the first or second line after receiving the CGP test was higher than that in the third or later lines (62.5% and 21.7%, respectively; P = 0.003). Rare cancer and early-line treatment were significantly and independently associated with ORR of matched therapies in multivariable analysis (P = 0.017 and 0.004, respectively).

CONCLUSION

Patients with rare cancer preferentially benefited from tumor mutation profiling by increasing the chances of therapeutic response to matched therapies. Early-line treatments after profiling increase the therapeutic benefit, irrespective of tumor types.

Microfluidic device-fabricated spiky nano-burflower shape gold nanomaterials facilitate large biomolecule delivery into cells using infrared light pulses

Photothermal nanoparticle-sensitised photoporation is an emerging approach, which is considered an efficient tool for the intracellular delivery of biomolecules. Nevertheless, using this method to achieve high transfection efficiency generally compromises cell viability and uneven distribution of nanoparticles results in non-uniform delivery. Here, we show that high aspect ratio gold nano-burflowers, synthesised in a microfluidic device, facilitate highly efficient small to very-large cargo delivery uniformly using infrared light pulses without sacrificing cell viability. By precisely controlling the flow rates of shaping reagent and reducing agent, high-density (24 numbers) sharply branched spikes (∼80 nm tip-to-tip length) of higher aspect ratios (∼6.5) with a small core diameter (∼45 nm) were synthesised. As produced gold burflower-shape nanoparticles are biocompatible, colloidally stable (large surface zeta potential value), and uniform in morphology with a higher plasmonic peak (max. 890 nm). Theoretical analysis revealed that spikes on the nanoparticles generate a higher electromagnetic field enhancement upon interaction with light pulses. It induces plasmonic nanobubbles in the vicinity of the cells, followed by pore formation on the membrane leading to diverse biomolecular delivery into cells. Our platform has been successfully implemented for uniform delivery of small to very large biomolecules, including siRNA (20-24 bp), plasmid DNA expressing green fluorescent protein (6.2 kbp), Cas-9 plasmid (9.3 kbp), and β-galactosidase enzyme (465 kDa) into diverse mammalian cells with high transfection efficiency and cell viability. For very large biomolecules such as enzymes, the best results were achieved as ∼100% transfection efficiency and ∼100% cell viability in SiHa cells. Together, our findings demonstrate that the spiky gold nano-burflower shape nanoparticles manufactured in a microfluidic system exhibited excellent plasmonic behaviour and could serve as an effective tool in manipulating cell physiology.

Massively Parallel High-Throughput Single-Cell Patterning and Large Biomolecular Delivery in Mammalian Cells Using Light Pulses

The recent advancements of single-cell analysis have significantly enhanced the ability to understand cellular physiology when compared to bulk cellular analysis. Here a massively parallel single-cell patterning and very large biomolecular delivery is reported. Micro-pillar polydimethyl siloxane stamp with different diameters (40-100 µm with 1 cm × 1 cm patterning area) is fabricated and then imprint distinct proteins and finally pattern single-cell to small clusters of cells depending on the micro-pillar diameters. The maximum patterning efficiency is achieved 99.7% for SiHa, 96.75% for L929, and 98.6% for MG63 cells, for the 100 µm micro-pillar stamp. For intracellular delivery of biomolecules into the patterned cells, a titanium micro-dish device is aligned on top of the cells and exposed by infrared light pulses. The platform successfully delivers small to very large biomolecules such as PI dyes (668 Da), dextran 3000 Da, siRNA (20-24 bp), and large size enzymes (464 KDa) in SiHa, L929 and MG63 cells. The delivery efficiency for PI dye, Dextran 3000, siRNA, and enzyme for patterned cells are ≈95 ± 3%, 97 ± 1%, 96 ± 1% and 94 ± 3%, with cell viability of 98 ± 1%. Thus, the platform is compact, robust, easy for printing, and potentially applicable for single-cell therapy and diagnostics.

Ultrathin SU-8 membrane for highly efficient tunable cell patterning and massively parallel large biomolecular delivery

Cell patterning is a powerful technique for the precise control and arrangement of cells, enabling detailed single-cell analysis with broad applications in therapeutics, diagnostics, and regenerative medicine. This study presents a novel and efficient technique that enables massively parallel high throughput cell patterning and precise delivery of small to large biomolecules into patterned cells. The innovative cell patterning device proposed in this study is a standalone, ultrathin 3D SU-8 micro-stencil membrane, with a thickness of 10 μm. It features an array of micro-holes ranging from 40 μm to 80 μm, spaced apart by 50 μm to 150 μm. By culturing cells on top of this SU-8 membrane, the technique achieves highly efficient cell patterns varying from single-cell to cell clusters on a Petri dish. Utilizing this technique, we have achieved a remarkable reproducible patterning efficiency for mouse fibroblast L929 (80.5%), human cervical SiHa (81%), and human neuroblastoma IMR32 (89.6%) with less than 1% defects in undesired areas. Single-cell patterning efficiency was observed to be highest at 75.8% for L929 cells. Additionally, we have demonstrated massively parallel high throughput uniform transfection of large biomolecules into live patterned cells by employing an array of titanium micro-rings (10 μm outer diameter, 3 μm inner diameter) activated through infrared light pulses. Successful delivery of a wide range of small to very large biomolecules, including propidium iodide (PI) dye (668.4 Da), dextran (3 kDa), siRNA (13.3 kDa), and β-galactosidase enzyme (465 kDa), was accomplished in cell patterns for various cancer cells. Notably, our platform achieved exceptional delivery efficiencies of 97% for small molecules like PI dye and 84% for the enzyme, with corresponding high cell viability of 100% and 90%, respectively. Furthermore, the compact and reusable SU-8-based membrane device facilitates highly efficient cell patterning, transfection, and cell viability, making it a promising tool for diagnostics and therapeutic applications.

Visible Pulsed Laser-Assisted Selective Killing of Cancer Cells with PVP-Capped Plasmonic Gold Nanostars

A new generation of nanoscale photosensitizer agents has improved photothermal capabilities, which has increased the impact of photothermal treatments (PTTs) in cancer therapy. Gold nanostars (GNS) are promising for more efficient and less invasive PTTs than gold nanoparticles. However, the combination of GNS and visible pulsed lasers remains unexplored. This article reports the use of a 532 nm nanosecond pulse laser and polyvinylpyrrolidone (PVP)-capped GNS to kill cancer cells with location-specific exposure. Biocompatible GNS were synthesized via a simple method and were characterized under FESEM, UV-visible spectroscopy, XRD analysis, and particle size analysis. GNS were incubated over a layer of cancer cells that were grown in a glass Petri dish. A nanosecond pulsed laser was irradiated on the cell layer, and cell death was verified via propidium iodide (PI) staining. We assessed the effectiveness of single-pulse spot irradiation and multiple-pulse laser scanning irradiation in inducing cell death. Since the site of cell killing can be accurately chosen with a nanosecond pulse laser, this technique will help minimize damage to the cells around the target cells.

Metallic micro-ring device for highly efficient large cargo delivery in mammalian cells using infrared light pulses

Uniform transfection of biomolecules into live cells with high delivery efficiency and cell viability is an immensely important area of biological research and has many biomedical applications. In the present study, we report highly efficient, uniform parallel intracellular delivery of small to very large biomolecules into diverse cell types using a titanium micro-ring (TMR) device activated by infrared (IR) light pulse. A TMR array device (2 cm × 2 cm) consists of a 10 μm outer diameter and 3 μm inner diameter for each micro-ring, and 10 μm interspacing between two micro-rings. Upon IR (1050 nm) pulse laser irradiation on the TMR device, photothermal cavitation bubbles are generated, disrupting the cell plasma membrane, and biomolecules are gently delivered into the cells by a simple diffusion process. This TMR device successfully delivered diverse types of small to very large biomolecules such as propidium iodide (PI; 668.4 Da) dye, dextran (3 kDa), small interfering RNA (13.3 kDa), enhanced green fluorescent protein expression plasmid DNA (6.2 kb), and β-galactosidase enzyme (465 kDa) into human cervical (SiHa), mouse fibroblast (L929), and mouse neural crest-derived (N2a) cancer cells. For smaller molecules (PI dye), delivery efficiency and cell viability were achieved at ∼96% and ∼97%, respectively, with a laser fluence of 21 mJ cm^-2 for 250 pulses. In contrast, ∼85% transfection efficiency and ∼90% cell viability were achieved for plasmid DNA with 45 mJ cm^-2 laser fluence for 250 pulses in SiHa cells. Moreover, the intracellular delivery of β-galactosidase enzyme was confirmed with confocal microscopy and flow cytometry analysis resulting in ∼83% co-staining of β-galactosidase enzyme and calcein AM. Based on these efficient deliveries of diverse types of biomolecules in different cell types, the device has the potential for cellular diagnostic and therapeutic applications.

Combinatorial physical methods for cellular therapy: Towards the future of cellular analysis?

The physical energy activated techniques for cellular delivery and analysis is one of the most rapidly expanding research areas for a variety of biological and biomedical discoveries. These methods, such as electroporation, optoporation, sonoporation, mechanoporation, magnetoporation, etc., have been widely used in delivering different biomolecules into a range of primary and patient-derived cell types. However, the techniques when used individually have had limitations in delivery and co-delivery of diverse biomolecules in various cell types. In recent years, a number of studies have been performed by combining the different membrane disruption techniques, either sequentially or simultaneously, in a single study. The studies, referred to as combinatorial, or hybrid techniques, have demonstrated enhanced transfection, such as efficient macromolecular and gene delivery and co-delivery, at lower delivery parameters and with high cell viability. Such studies can open up new and exciting avenues for understanding the subcellular structure and consequently facilitate the development of novel therapeutic strategies. This review consequently aims at summarising the different developments in hybrid therapeutic techniques. The different methods discussed include mechano-electroporation, electro-sonoporation, magneto-mechanoporation, magnetic nanoparticles enhanced electroporation, and magnetic hyperthermia studies. We discuss the clinical status of the different methods and conclude with a discussion on the future prospects of the combinatorial techniques for cellular therapy and diagnostics.

Automated detection of patterned single-cells within hydrogel using deep learning

Single-cell analysis has been widely used in various biomedical engineering applications, ranging from cancer diagnostics, and immune response monitoring to drug screening. Single-cell isolation is fundamental for observing single-cell activities and an automatic finding method of accurate and reliable cell detection with few possible human errors is also essential. This paper reports trapping single cells into photo patternable hydrogel microwell arrays and isolating them. Additionally, we present an object detection-based DL algorithm that detects single cells in microwell arrays and predicts the presence of cells in resource-limited environments at the highest possible mAP (mean average precision) of 0.989 with an average inference time of 0.06 s. This algorithm leads to the enhancement of the high-throughput single-cell analysis, establishing high detection precision and reduced experimentation time.

Mixing Performance of a Planar Asymmetric Contraction-and-Expansion Micromixer

Micromixers are one of the critical components in microfluidic devices. They significantly affect the efficiency and sensitivity of microfluidics-based lab-on-a-chip systems. This study introduces an efficient micromixer with a simple geometrical feature that enables easy incorporation in a microchannel network without compromising the original design of microfluidic devices. The study proposes a newly designed planar passive micromixer, termed a planar asymmetric contraction-and-expansion (P-ACE) micromixer, with asymmetric vertical obstacle structures. Numerical simulation and experimental investigation revealed that the optimally designed P-ACE micromixer exhibited a high mixing efficiency of 80% or more within a microchannel length of 10 mm over a wide range of Reynolds numbers (0.13 ≤ Re ≤ 13), eventually attaining approximately 90% mixing efficiency within a 20 mm microchannel length. The highly asymmetric geometric features of the P-ACE micromixers enhance mixing because of their synergistic effects. The flow velocities and directions of the two fluids change differently while alternately crossing the longitudinal centerline of the microchannel, with the obstacle structures asymmetrically arranged on both sidewalls of the rectangular microchannel. This flow behavior increases the interfacial contact area between the two fluids, thus promoting effective mixing in the P-ACE micromixer. Further, the pressure drops in the P-ACE micromixers were experimentally investigated and compared with those in a serpentine micromixer with a perfectly symmetric mixing unit.

A microfluidic diagnostic device with air plug-in valves for the simultaneous genetic detection of various food allergens

The identification of accidental allergen contamination in processed foods is crucial for risk management strategies in the food processing industry to effectively prevent food allergy incidents. Here, we propose a newly designed passive stop valve with high pressure resistance performance termed an “air plug-in valve” to further improve microfluidic devices for the detection of target nucleic acids. By implementing the air plug-in valve as a permanent stop valve, a maximal allowable flow rate of 70 µL/min could be achieved for sequential liquid dispensing into an array of 10 microchambers, which is 14 times higher than that achieved with the previous valve arrangement using single-faced stop valves. Additionally, we demonstrate the simultaneous detection of multiple food allergens (wheat, buckwheat, and peanut) based on the colorimetric loop-mediated isothermal amplification assay using our diagnostic device with 10 microchambers compactly arranged in a 20-mm-diameter circle. After running the assays at 60 °C for 60 min, any combination of the three types of food allergens and tea plant, which were used as positive and negative control samples, respectively, yielded correct test results, without any cross-contamination among the microchambers. Thus, our diagnostic device will provide a rapid and easy sample-to-answer platform for ensuring food safety and security.

Microfluidic mechanoporation for cellular delivery and analysis

Highly efficient intracellular delivery strategies are essential for developing therapeutic, diagnostic, biological, and various biomedical applications. The recent advancement of micro/nanotechnology has focused numerous researches towards developing microfluidic device-based strategies due to the associated high throughput delivery, cost-effectiveness, robustness, and biocompatible nature. The delivery strategies can be carrier-mediated or membrane disruption-based, where membrane disruption methods find popularity due to reduced toxicity, enhanced delivery efficiency, and cell viability. Among all of the membrane disruption techniques, the mechanoporation strategies are advantageous because of no external energy source required for membrane deformation, thereby achieving high delivery efficiencies and increased cell viability into different cell types with negligible toxicity. The past two decades have consequently seen a tremendous boost in mechanoporation-based research for intracellular delivery and cellular analysis. This article provides a brief review of the most recent developments on microfluidic-based mechanoporation strategies such as microinjection, nanoneedle arrays, cell-squeezing, and hydroporation techniques with their working principle, device fabrication, cellular delivery, and analysis. Moreover, a brief discussion of the different mechanoporation strategies integrated with other delivery methods has also been provided. Finally, the advantages, limitations, and future prospects of this technique are discussed compared to other intracellular delivery techniques.

Microfluidic platforms for single neuron analysis

Single-neuron actions are the basis of brain function, as clinical sequelae, neuronal dysfunction or failure for most of the central nervous system (CNS) diseases and injuries can be identified via tracing single-neurons. The bulk analysis methods tend to miscue critical information by assessing the population-averaged outcomes. However, its primary requisite in neuroscience to analyze single-neurons and to understand dynamic interplay of neurons and their environment. Microfluidic systems enable precise control over nano-to femto-liter volumes via adjusting device geometry, surface characteristics, and flow-dynamics, thus facilitating a well-defined micro-environment with spatio-temporal control for single-neuron analysis. The microfluidic platform not only offers a comprehensive landscape to study brain cell diversity at the level of transcriptome, genome, and/or epigenome of individual cells but also has a substantial role in deciphering complex dynamics of brain development and brain-related disorders. In this review, we highlight recent advances of microfluidic devices for single-neuron analysis, i.e., single-neuron trapping, single-neuron dynamics, single-neuron proteomics, single-neuron transcriptomics, drug delivery at the single-neuron level, single axon guidance, and single-neuron differentiation. Moreover, we also emphasize limitations and future challenges of single-neuron analysis by focusing on key performances of throughput and multiparametric activity analysis on microfluidic platforms.

A method of sequential liquid dispensing for the multiplexed genetic diagnosis of viral infections in a microfluidic device

In this study, we introduce polydimethylsiloxane (PDMS)-based microfluidic devices capable of sequential dispensing of samples into multiple reaction microchambers in a single operation to provide a fast and easy sample-to-answer platform for multiplexed genetic diagnosis of multiple viral infectious diseases. This approach utilizes the loop-mediated isothermal amplification (LAMP) method to amplify and detect specific nucleic acid (DNA/RNA) targets. We present a microfluidic flow control theory for sequential liquid dispensing phenomena, which provides design guidelines for device optimization. The device specifications, such as the possible dispensing number and maximal allowable flow rate, can be theoretically designed by optimizing the geometric dimensions of the microchannels and a pair of passive stop valves integrated into each microchamber together with the water contact angles of the materials used to fabricate the microfluidic devices. In addition, a passive stop valve with a vertical-type phaseguide structure was designed to improve device performance. We could simultaneously diagnose coronavirus disease 2019 (COVID-19) and other infectious diseases, such as severe acute respiratory syndrome (SARS), seasonal influenza A, and pandemic influenza A (H1N1) 2009. The colorimetric reverse transcription LAMP (RT-LAMP) assay suggests that the four viral infectious diseases can be detected within 30 min using a hue-based quantitative analysis, and the naked eye using our microfluidic devices.

Microfluidic nanomaterials: From synthesis to biomedical applications

Microfluidic platforms gain popularity in biomedical research due to their attractive inherent features, especially in nanomaterials synthesis. This review critically evaluates the current state of the controlled synthesis of nanomaterials using microfluidic devices. We describe nanomaterials' screening in microfluidics, which is very relevant for automating the synthesis process for biomedical applications. We discuss the latest microfluidics trends to achieve noble metal, silica, biopolymer, quantum dots, iron oxide, carbon-based, rare-earth-based, and other nanomaterials with a specific size, composition, surface modification, and morphology required for particular biomedical application. Screening nanomaterials has become an essential tool to synthesize desired nanomaterials using more automated processes with high speed and repeatability, which can't be neglected in today's microfluidic technology. Moreover, we emphasize biomedical applications of nanomaterials, including imaging, targeting, therapy, and sensing. Before clinical use, nanomaterials have to be evaluated under physiological conditions, which is possible in the microfluidic system as it stimulates chemical gradients, fluid flows, and the ability to control microenvironment and partitioning multi-organs. In this review, we emphasize the clinical evaluation of nanomaterials using microfluidics which was not covered by any other reviews. In the future, the growth of new materials or modification in existing materials using microfluidics platforms and applications in a diversity of biomedical fields by utilizing all the features of microfluidic technology is expected.

Sex-specific associations of evening blood pressure burden and cardiac load with nocturia severity in the Japanese at high-risk of cardiovascular disease

Background

Earlier epidemiologic studies have reported a significant relationship between hypertension and nocturia. However, the underlying pathophysiology has not been established. We hypothesized that blood pressure (BP) burden, the classes of antihypertensive agents and cardiac load were associated with severity of nocturia, and that these associations might be moderated by gender.

Purpose

To investigate the relationships of home BP (HBP) level, the class of antihypertensive agent, brain natriuretic peptide (BNP) with nocturia severity, and to investigate these associations stratified by gender in the Japanese at high-risk of cardiovascular disease.

Methods

In the Japan Morning Surge-Home Blood Pressure Study, measurements of HBP at evening (mean 11.2 days) as well as BNP were performed in the 4310 patients with one or more cardiovascular risks (64.9 years old, male 47%). A self-administered questionnaire included items on nocturia was used.

Results

According to the number of nocturia (no void: n=2382; one void: n=847; >2 voids per night: n=1082), significant associations of systolic BP (SBP) at evening (130 vs 130 vs 132 mmHg, p<0.0001) and logBNP (1.20 vs 1.30 vs 1.42, p<0.0001) were observed with nocturia severity. In the multinomial logistic regression analysis adjustment for confounders including age, smoking, total cholesterol, fasting blood glucose, HbA1c and clinic SBP, the use of diuretics (OR: 1.26, 95% CI: 1.06–1.52, p<0.05) was significantly associated with one nocturnal void, while evening SBP (OR: 1.009, 95% CI: 1.003–1.014, p<0.01) and logBNP (1.43, 95% CI: 1.19–1.73, p<0.001) were significantly associated with multiple nocturnal voids. While no significant interaction was found between evening SBP and logBNP for multiple nocturnal voids in the total population, a significant interaction was found between evening SBP and logBNP for multiple nocturnal voids in females (p<0.05).

Conclusions

In this study, the use of diuretics was a significant indicator of single nocturnal void, while evening SBP and BNP were those of multiple nocturnal voids in the high-risk Japanese population. Specifically, in the females, treatment to reduce BP burden as well as cardiac overload might be important to improve sleep disturbance caused by nocturia.

Funding Acknowledgement

Type of funding sources: None.

Electrochemical fabrication of TiO2 micro-flowers for an efficient intracellular delivery using nanosecond light pulse

Introduction of foreign cargo into the targeted living cell with high transfection efficiency and high cell viability is an important mean for many biological and biomedical research purpose. Here, we have demonstrated a newly developed Titanium oxide micro-flower structure (TMS) for intracellular delivery. The TMS were formed on titanium (Ti) substrate using an electrochemical anodization process. The TMS consists of branches of titanium dioxide (TiO2) nanotubes, which play an important role in efficient cargo delivery. Due to nanosecond pulse laser exposure, Ti substrate heat-up, generating cavitation bubbles. These bubbles can rapidly grow, coalesce, and collapse to induce explosion resulting in very strong fluid flow through the TiO2 nanotubes and disrupt the cell plasma membrane promoting the delivery of biomolecules into cells. Using this platform, we successfully deliver dyes with 93% efficiency and nearly 98% cell viability into HCT cells, and this technique is potentially applicable for cellular therapy and diagnostics.

A Review of Single-Cell Adhesion Force Kinetics and Applications

Cells exert, sense, and respond to the different physical forces through diverse mechanisms and translating them into biochemical signals. The adhesion of cells is crucial in various developmental functions, such as to maintain tissue morphogenesis and homeostasis and activate critical signaling pathways regulating survival, migration, gene expression, and differentiation. More importantly, any mutations of adhesion receptors can lead to developmental disorders and diseases. Thus, it is essential to understand the regulation of cell adhesion during development and its contribution to various conditions with the help of quantitative methods. The techniques involved in offering different functionalities such as surface imaging to detect forces present at the cell-matrix and deliver quantitative parameters will help characterize the changes for various diseases. Here, we have briefly reviewed single-cell mechanical properties for mechanotransduction studies using standard and recently developed techniques. This is used to functionalize from the measurement of cellular deformability to the quantification of the interaction forces generated by a cell and exerted on its surroundings at single-cell with attachment and detachment events. The adhesive force measurement for single-cell microorganisms and single-molecules is emphasized as well. This focused review should be useful in laying out experiments which would bring the method to a broader range of research in the future.

Is warfarin associated with higher risk of thrombus in left atrial appendage than direct oral anticoagulants?

Funding Acknowledgements

Type of funding sources: None.

Background

Thrombus in left atrial appendage (LAA) is associated with cardiogenic ischemic stroke, and anticoagulation therapy is utilized to prevent thromboembolism.

Purpose

This study is to investigate the incidence of thrombus in left atrial appendage detected by transoesophageal echocardiography (TOE) under anticoagulation therapy with warfarin or direct oral anticoagulants (DOAC).

Methods

Between 2005 and 2016, the patients who underwent TOE under anticoagulation therapy due to atrial fibrillation more than one month were enrolled in this study. The patients were divided into 2 groups according to whether treated with warfarin or DOAC and baseline characteristics and incidence of LAA thrombus were assessed.

Results

Among the 313 study patients, 243 (78%) were treated with warfarin. The patients treated with warfarin were elder (median 73 y vs. 67 y [interquartile range 66 – 78 y vs. 58 – 72 y], P < 0.01), the body mass index was lower (23.2 vs. 24.0 [21.0 – 25.4 vs. 21.3 – 26.9], P = 0.03). The prevalence of male sex (64% vs. 71%, P = 0.26) were similar between the 2 groups. The previous history of hypertension (69% vs. 59%, P = 0.10), diabetes (24% vs. 19%, P = 0.32), vascular disease (30% vs. 26%, P = 0.52), and ischemic stroke were similar between the 2 groups (30% vs. 23%, P = 0.22). The prevalence of CHA2DS2-VASc score > 1 (84% vs. 59%, P < 0.01) and the d-dimer level (0.7 vs. 0.5 mcg/ml [0.5 – 1.8 vs. 0.5 – 0.5 mcg/ml], P < 0.01) were higher in the warfarin groups than those of the DOAC. The velocity of LAA was slower in the warfarin group than those of DOAC (35 vs. 55 cm/s [21 – 54 vs. 38 – 68 cm/s], P < 0.01). The incidence of detection of LAA thrombus was 19% in the warfarin group and 3% in the DOAC group (P < 0.01). In the warfarin group, the PT-INR were lower in the patients with LAA thrombus (1.38 vs. 1.66 [1.11 – 1.92 vs. 1.34 – 2.03], P = 0.03).

Conclusions

The higher risk of ischemic stroke and out of range PT-INR may be the cause of the higher incidence of LAA thrombus in the patients treated with warfarin than those with DOAC.

Abstract Figure.

Fabrication of TiO2 microspikes for highly efficient intracellular delivery by pulse laser-assisted photoporation

The introduction of foreign cargo into living cells with high delivery efficiency and cell viability is a challenge in cell biology and biomedical research. Here, we demonstrate a nanosecond pulse laser-activated photoporation for highly efficient intracellular delivery using titanium dioxide (TiO₂) microspikes as a substratum. The TiO₂ microspikes were formed on titanium (Ti) substrate using an electrochemical anodization process. Cells were cultured on top of the TiO₂ microspikes as a monolayer, and the biomolecule was added. Due to pulse laser exposure of the TiO₂ microspike–cell membrane interface, the microspikes heat up and induce cavitation bubbles, which rapidly grow, coalesce and collapse to induce explosion, resulting in very strong fluid flow at the cell membrane surface. Thus, the cell plasma membrane disrupts and creates transient nanopores, allowing delivery of biomolecules into cells by a simple diffusion process. By this technique, we successfully delivered propidium iodide (PI) dye in HeLa cells with high delivery efficiency (93%) and high cell viability (98%) using 7 mJ pulse energy at 650 nm wavelength. Thus, our TiO₂ microspike-based platform is compact, easy to use, and potentially applicable for therapeutic and diagnostic purposes.

The introduction of foreign cargo into living cells with high delivery efficiency and cell viability by laser asisted photoporation on TiO₂ microspikes platform.

Formation of nanostructures on magnesium alloy by anodization for potential biomedical applications

In the present work, we have investigated the formation of nanostructures on AZ31 magnesium alloy using electrochemical anodization technique. The formed nanostructures were efficiently showed bone-like apatite formation followed by its gradual increase, when immersed in simulated body fluid (SBF) and it exhibited controlled degradation in 7 days. Cell viability study was performed using MG-63 cells (human osteosarcoma cell lines) and revealed that the nanostructured surface has excellent biocompatibility by enhancing both cell adhesion and cell growth. The detailed characterization of this anodized surface was evaluated by field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS). Furthermore, surface-corrosion before and after anodization was examined by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies in SBF. The in-depth studies bring out the fact that native oxide in the sample is converted to a biocompatible nanostructure, which is created due to anodization in a particular electrolyte solution containing ethylene glycol and hybrid hydrofluoric acid mixture.

Prognosis and cause of death in patients with left atrial appendage thrombus treated with or without anticoagulation therapy

Background

Thrombus in left atrial appendage (LAA) is associated with cardiogenic ischemic stroke; however, little is known about prognosis of patients with LAA thrombus detected by transoesophageal echocardiography (TOE).

Purpose

This study is to investigate the prognosis of patients with LAA thrombus and their cause of death.

Methods

Between 2005 and 2016, the patients who were performed TOE in our hospital were enrolled in this retrospective observational study. Five-year stroke free and survival curves were constructed by Kaplan-Meir method and cause of death were assessed.

Results

Among the 1263 study patients, LAA thrombus was detected in 146 (12%) patients. The patients with LAA thrombus were elder (74 y [66–79 y] vs. 70 y [62–76 y], P<0.001), than those without LAA thrombus, respectively. The prevalence of male sex (67% vs. 69%, P=0.63) were similar between the 2 groups. The prevalence of CHA2DS2-VASc score ≥2, d-dimer (1.7 mcg/ml [0.9–3.5 mcg/ml] vs. 0.8 mcg/ml [0.5–2.2 mcg/ml], P<0.001), and plasma brain natriuretic peptide (315 pg/ml [128–515 pg/ml] vs. 126 pg/ml [47–284 pg/ml], P<0.001) were higher in the patients with LAA thrombus than those without (89% vs. 78%, P=0.003). The LAA velocity was slower in the patients with LAA thrombus than those without (23 cm/s [15–34 cm/s] vs. 51 cm/s [35–72 cm/s], P<0.001). The prevalence of receiving anticoagulation therapy before (34% vs. 24%, P=0.01) and after (98% vs. 66%, P<0.001) TOE 1 month were higher in the patients with LAA thrombus than those without. The 5-year stroke free rate was lower in the patients with LAA thrombus than those without (82% vs. 93%, P<0.001); however, the 5-year survival were similar between the 2 groups (84% vs. 84%, P=0.93) (Figure). The cause of death as ischemic stroke was only 7% (1/14) and 3% (3/94), (P=0.43); the cardiac cause (14% vs. 43%, P=0.07) and the malignancy (35% vs. 29%, P=0.75) were the frequent cause of death in the patient with LAA thrombus and those without, respectively.

Conclusions

The patients who were detected thrombus in the LAA had higher incidence of ischemic stroke; however, the 5-y survival were similar. The ischemic stroke was not major cause of death in the patients with and without LAA thrombus. The higher rate of receiving anticoagulation therapy may be one of the causes of the discrepancy.

Figure 1

Funding Acknowledgement

Type of funding source: None

Sex-dependent association between day-by-day morning blood pressure variability and common carotid artery intima-media thickness: the J-HOP study

Background

Day-by-day home systolic blood pressure variability (BPV) was shown to be associated with increased common carotid artery (CCA) intima-media thickness (IMT) in the hypertensives. Recently, 24 hour ambulatory BPV was revealed to serve as an indicator of higher CCA-IMT only in males. However, there have been no studies that reported the sex-dependent relationship between day-by-day BPV and CCA-IMT.

Purpose

We assessed the hypothesis that day-by-day BPV was associated with higher CCA-IMT in the Japanese males at high-risk of cardiovascular disease.

Methods

Among 4310 patients with one or more cardiovascular risks recruited for the Japan Morning Surge-Home Blood Pressure Study, carotid ultrasound in CCA was performed in the 1365 patients (mean age 65.6 years old, male 52%). The home blood pressure (BP) readings during mean 11.2 days were used to calculate home mean levels and variability in morning systolic BP (SBP). Day-by-day BPV was measured as standard deviation [SD] and delta (maximum-minimum) in SBP.

Results

Average mean CCA-IMT of left and right side was 1.046±0.4mm. Mean (r=0.118, p<0.0001), SD (r=0.120, p<0.0001) and delta (r=0.149, p<0.0001) in morning SBP were significantly correlated with CCA-IMT. In the multiple regression analysis adjustment for confounders including age, gender, body mass index, total cholesterol, high density lipoprotein and mean morning SBP, SD (B: 0.008, 95% CI: 0.001–0.015, p<0.05) or delta (B: 0.004, 95% CI: 0.002–0.006, p<0.001) in morning SBP each had a significant association with CCA-IMT. According to the gender, SD (p<0.01) or delta (p<0.01) in morning SBP each was significantly associated with CCA-IMT only in the male group while neither SD (p=0.4) nor delta (p=0.4) in morning SBP was associated with CCA-IMT in the female group.

Conclusions

In addition to the conventional risk factors, day-by-day morning SBP variability was a significant indicator of increased CCA-IMT in the high-risk Japanese population. The significant relationship between day-by-day morning SBP variability and CCA-IMT was observed only in the males. Gender specific impact of day-by-day morning home systolic BPV on carotid artery atherosclerosis should be taken into account in the high-risk elderly at cardiovascular disease.

Funding Acknowledgement

Type of funding source: None

Infrared Pulse Laser-Activated Highly Efficient Intracellular Delivery Using Titanium Microdish Device

We report infrared (IR) pulse laser-activated highly efficient parallel intracellular delivery by using an array of titanium microdish (TMD) device. Upon IR laser pulse irradiation, a two-dimensional array of TMD device generated photothermal cavitation bubbles to disrupt the cell membrane surface and create transient membrane pores to deliver biomolecules into cells by a simple diffusion process. We successfully delivered the dyes and different sizes of dextran in different cell types with variations of laser pulses. Our platform has the ability to transfect more than a million cells in a parallel fashion within a minute. The best results were achieved for SiHa cells with a delivery efficiency of 96% and a cell viability of around 98% for propidium iodide dye using 600 pulses, whereas a delivery efficiency of 98% and a cell viability of 100% were obtained for dextran 3000 MW delivery using 700 pulses. For dextran 10,000 MW, the delivery efficiency was 92% and the cell viability was 98%, respectively. The device is compact, easy-to-use, and potentially applicable for cellular therapy and diagnostic purposes.

A Microfluidic Diagnostic Device Capable of Autonomous Sample Mixing and Dispensing for the Simultaneous Genetic Detection of Multiple Plant Viruses

As an efficient approach to risk management in agriculture, the elimination of losses due to plant diseases and insect pests is one of the most important and urgent technological challenges for improving the crop yield. Therefore, we have developed a polydimethylsiloxane (PDMS)-based microfluidic device for the multiplex genetic diagnosis of plant diseases and pests. It offers unique features, such as rapid detection, portability, simplicity, and the low-cost genetic diagnosis of a wide variety of plant viruses. In this study, to realize such a diagnostic device, we developed a method for the autonomous dispensing of fluid into a microchamber array, which was integrated with a set of three passive stop valves with different burst pressures (referred to as phaseguides) to facilitate precise fluid handling. Additionally, we estimated the mixing efficiencies of several types of passive mixers (referred to as chaotic mixers), which were integrated into a microchannel, through experimental and computational analyses. We first demonstrated the ability of the fabricated diagnostic devices to detect DNA-based plant viruses from an infected tomato crop based on the loop-mediated isothermal amplification (LAMP) method. Moreover, we demonstrated the simultaneous detection of RNA-based plant viruses, which can infect cucurbits, by using the reverse transcription LAMP (RT-LAMP) method. The multiplex RT-LAMP assays revealed that multiple RNA viruses extracted from diseased cucumber leaves were successfully detected within 60 min, without any cross-contamination between reaction microchambers, on our diagnostic device.

Photocatalytic Nanofabrication and Intracellular Raman Imaging of Living Cells with Functionalized AFM Probes

Atomic force microscopy (AFM) is an effective platform for in vitro manipulation and analysis of living cells in medical and biological sciences. To introduce additional new features and functionalities into a conventional AFM system, we investigated the photocatalytic nanofabrication and intracellular Raman imaging of living cells by employing functionalized AFM probes. Herein, we investigated the effect of indentation speed on the cell membrane perforation of living HeLa cells based on highly localized photochemical oxidation with a catalytic titanium dioxide (TiO2)-functionalized AFM probe. On the basis of force-distance curves obtained during the indentation process, the probability of cell membrane perforation, penetration force, and cell viability was determined quantitatively. Moreover, we explored the possibility of intracellular tip-enhanced Raman spectroscopy (TERS) imaging of molecular dynamics in living cells via an AFM probe functionalized with silver nanoparticles in a homemade Raman system integrated with an inverted microscope. We successfully demonstrated that the intracellular TERS imaging has the potential to visualize distinctly different features in Raman spectra between the nucleus and the cytoplasm of a single living cell and to analyze the dynamic behavior of biomolecules inside a living cell.

Scalable Parallel Manipulation of Single Cells Using Micronozzle Array Integrated with Bidirectional Electrokinetic Pumps

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 V_pp, and V_DC: -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.

P684 Paradoxical cerebral infarction due to massive pulmonary embolism in extracorporeal cardiopulmonary resuscitation and surgical embolectomy

Introduction

Paradoxical cerebral infarction is a mechanism of acute ischemic stroke; however, definitive images to diagnose paradoxical embolism are not often obtained. We report a case of paradoxical cerebral embolism complicated with cardiac arrest due to massive pulmonary embolism.

Case report

A 40-year-old man presented due to sudden-onset chest pain, and was admitted to our hospital. He was restless and had cold sweat; we could not measure blood pressure. Electrocardiography showed wide QRS complex with right bundle branch block, and T wave inversion in leads V1 and III. Transthoracic echocardiography showed diffuse severe left ventricular hypokinesis, with slightly better inferior wall motion compared to other segments. Few minutes after arriving, he experienced cardiac arrest; chest compression was initiated. He was transported to the catheter laboratory, and veno-arterial extracorporeal membrane oxygenation was initiated subsequently. To diagnose the cause of arrest, we performed coronary angiography, which revealed no occluded coronary artery. Pulmonary angiograms showed bilateral proximal pulmonary artery occlusion with massive thrombi (panel A). Surgical embolectomy was performed after cardiac team discussion. After ICU admission post-surgery, pericardial effusion was increased, and the blood drained continuously from the chest tube; a large amount of blood transfusion was required. Reopen chest haemostasis was utilised. After the second ICU admission, anisocoria was observed; subsequent computed tomography showed low density and midline shift in almost the entire left cerebral hemisphere (Panel B). Carotid duplex ultrasound revealed a large thrombus saddled at the left carotid artery bifurcation (Panel C and D). We rechecked the transthoracic echocardiogram at arrival to reveal the cause of the cerebral infarction, which showed the thrombus to be at the ascending aorta (Panel E). We thought that the thrombi had moved from the lower limb to the right atrium. The massive pulmonary embolism increased the pulmonary artery and right atrial pressure, resulting in the lower pressure of the left atrium compared to that of the right atrium. The thrombi passed through the patent foramen ovale into the left atrium, moved into the left ventricle, and embolised the left internal carotid artery (Panel F). He expired due to severe neurologic injury from brain herniation.

Conclusion

In this case, although the pulmonary embolism was massive and led to cardiac arrest, the deteriorated haemodynamics improved by extracorporeal cardiopulmonary resuscitation and surgical embolectomy. However, we could not rescue the patient because of the severe neurological injury due to paradoxical embolism. Paradoxical cerebral infarction in pulmonary embolism is rare; however, we should pay careful attention to early detection of paradoxical cerebral infarction in pulmonary embolism and treatment for return of the patient to the former lifestyle.

Abstract P684 figure

P765 Does detection of thrombus in left atrial appendage increase risk of ischemic stroke and mortality?

Background

Left atrial appendage (LAA) thrombus is one of causes of cardiogenic stroke and detection of LAA thrombus by transoesophageal echocardiography (TOE) strongly suggest cardiogenic stroke. It was reported that cardiogenic stroke patients had higher in-hospital mortality about 19%; however, little is known about LAA thrombus and mortality after indexed detection of LAA thrombus. We investigated LAA thrombus detection and their prognosis including ischemic stroke and survival.

Methods

The patients who were performed TOE between 2005 and 2016 in our hospital were enrolled in this study. Patients were divided into 2 groups based on thrombus detection in the LAA, and baseline characteristics and outcomes including prevalence of 5-y stroke-free and survival from the indexed TOE were compared.

Results

Among the 1260 study patients, the follow-up duration was median 971 d (interquartile range 345 d – 2017 d), and 67% of the patients were performing TOE for atrial fibrillation (AF), 20% for cerebral infarction, and 14% for valvular heart disease. Non-valvular AF was seen in 64% of the study patients and rheumatic AF was in 2%. The age (74 y [66 y – 79 y] vs 70 y [62 y – 76 y], p < 0.001), the prevalence of male sex (67% vs 69%, p = 0.63), and hemoglobin level (13.9 g/dl [12.5 – 15.1 g/dl] vs 13.8 g/dl [12.4 – 14.9 g/dl], p = 0.49) were similar between the patients with LAA thrombus and those without. The CHA2DS2-VASc score (p = 0.008), the prevalence of receiving anticoagulation before TOA (34% vs 24%, p = 0.01), those of after TOA (98% vs 66%, p < 0.001), serum creatinine (0.92 mg/dl [0.80 – 1.10 mg/dl] vs 0.85 mg/dl [0.71 – 1.00 mg/dl], p < 0.001), d-dimer level (1.7 mcg/ml [0.9 – 3.5 mcg/ml] vs 0.8 mcg/ml [0.5 – 2.2 mcg/ml], p < 0.001), and plasma brain natriuretic peptide (315 pg/ml [128 – 515 pg/ml] vs 126 pg/ml [47 – 284 pg/ml], p < 0.001) were higher in the patients with LAA thrombus than those without. The 5-y ischemic stroke-free rate was lower in the patients with LAA thrombus than those without (p < 0.001) (Figure, Panel A); however, the 5-y survival was similar between the 2 groups (p = 0.93) (Panel B).

Conclusions

The patients who were detected thrombus in the LAA had higher incidence of ischemic stroke, but the survival rate were similar. The higher rate of receiving anticoagulation therapy in the patients with LAA thrombus may be the cause of this discrepancy. Further studies are necessary to clarify this issue.

Abstract P765 Figure

Reasons for discontinuation of contraception among women with a current unintended pregnancy in 36 low and middle-income countries

OBJECTIVES

To explore the reasons for discontinuation of the last contraceptive method used in women with a current unintended pregnancy.

STUDY DESIGN

We conducted a retrospective analysis using contraceptive calendar data from Demographic and Health Surveys from 36 low- and middle-income countries from 2005 through 2014. The prevalence of contraception utilization and the contribution of each reason for contraceptive discontinuation was calculated, at country level as well as for the pooled dataset, for 10,901 women aged 15-49 before the current unintended pregnancies.

RESULTS

Unintended pregnancies ranged from 5.5% of all pregnancies in the Kyrgyz Republic to 60.0% in Colombia and Peru. In Central Asian and in six African countries, over 80% of women with a current unintended pregnancy had not used any contraceptives in the previous five years. Use of long-acting modern methods remained consistently low across all countries. Among women who last used a traditional method, 83.8% discontinued due to failure. Among women who last used a long-acting modern method, 40.2% discontinued because of side effects.

CONCLUSIONS

Our findings confirm that more than 65.0% of women with an unintended pregnancy in 36 low and middle-income countries were either non-users or using traditional methods. An additional 31.2% were using short-acting modern methods. Long-acting methods would have prevented the overwhelming majority of unintended pregnancies.

IMPLICATIONS

This paper shows the need for the health system to support use of suitable methods, reduce switching failure and identify early when women are having concerns about the method they are using.

P4548Early drop in systolic blood pressure and worsening renal function in the elderly acute heart failure: how does heart rate interact?

Background

Renal dysfunction is a frequent finding in patients hospitalized for acute heart failure (AHF). Worsening renal function (WRF) during hospitalization was found to be related with a poor outcome independently of baseline renal function. Early drop in systolic blood pressure (SBP) has shown to predict WRF in AHF. However, there have been few studies that reported the impact of on-admission heart rate (HR) on the relationship between early SBP drop and WRF in the elderly AHF.

Purpose

We assessed the hypothesis that early SBP drop predict WRF in the elderly patients with AHF, and investigated that on-admission HR might have an interaction with that relationship.

Methods

SBP and HR were measured on admission and 6 times during 48 hours in the 245 elderly AHF inpatients (82.9±6.0 years old, male 49.4%). WRF was defined as a serum creatinine increase of ≥0.3 mg/dL by Day 5. Early drop in SBP was calculated as the difference between admission and the lowest value measured during the first 48 hour of hospitalization.

Results

Early SBP drop (51.3 vs 32.5mmHg, p<0.01) and on-admission HR (79.3 vs 89.6bpm, p<0.05) were significantly different between the group with WRF (n=36) and the group without WRF (n=209). In the multiple logistic regression analysis adjusted for the confounders including age, gender, hypertension, left ventricular ejection fraction, total cholesterol, BNP, baseline creatinine, beta-blockade use, intravenous loop diuretic, isosorbide dinitrate and carperitide use, early SBP drop (OR: 1.003, 95% CI: 1.003–1.03, p<0.04) and on-admission HR (OR: 0.98, 95% CI: 0.96–0.99, p<0.01) were significantly associated with WRF. The interaction term of early SBP drop by on-admission HR did not have a significant association with WRF (p=0.3).

Conclusions

In the elderly AHF patients, exaggerated early SBP drop and lower on-admission HR were shown as significant independent predictors of WRF. These two factors were additively associated with WRF. Too much reduction in SBP and that in HR might be harmful to renal circulation in AHF.

Phototactic Algae-Driven Unidirectional Transport of Submillimeter-Sized Cargo in a Microchannel

The sensing and actuation capabilities of biological cells integrated with artificial components have been used to create autonomous microsystems. For creating autonomous microsystems, the unidirectional transport of a submillimeter-sized cargo with stimuli responsive bio-motors should be developed as a fundamental motion. This study aims to use Volvox as a light-controlled microrobot to achieve the unidirectional transport of a submillimeter-sized cargo. We show the fabrication of a guide structure, cargo, and light irradiation platform for a unidirectional actuation. The fundamental performances of each component were investigated, and the motions of Volvox were controlled in a microchamber with the developed light irradiation platform. All components were integrated to demonstrate the unidirectional actuation of a block by Volvox. We discuss the dynamics of the mechanical motions.

Current Trends of Microfluidic Single-Cell Technologies

The investigation of human disease mechanisms is difficult due to the heterogeneity in gene expression and the physiological state of cells in a given population. In comparison to bulk cell measurements, single-cell measurement technologies can provide a better understanding of the interactions among molecules, organelles, cells, and the microenvironment, which can aid in the development of therapeutics and diagnostic tools. In recent years, single-cell technologies have become increasingly robust and accessible, although limitations exist. In this review, we describe the recent advances in single-cell technologies and their applications in single-cell manipulation, diagnosis, and therapeutics development.