Generation Of Microparticles Research Articles

Development of magnesium-based hybrid metal matrix composite through in situ micro, nano reinforcements

Present work aims at developing Magnesium based metal matrix composite (MMC) through in-situ reaction. In-situ generation of micro and nano particles in the Mg-melt is supposed to have a better bonding with the matrix. Ceric ammonium nitrate (CAN) is added to initial Magnesium melt (with an aim to generate CeO2 and MgO through in-situ reaction) at temperatures of 670 °C and 870 °C. The developed MMCs are solution treated to get rid of intermetallic. The nature of particles is explored with X-ray diffraction (XRD) and Energy dispersion spectroscopy (EDS). The morphology and sizes of particles are keenly jotted using scanning electron microscope (SEM). Mechanical responses of developed MMCs are recorded through Hardness, Compression and scratch tests. The compression fractured surfaces are analyzed with SEM and scratched samples are analyzed on 3 D optical profilometer to explore deformation behavior. The observations indicate the in-situ formation of CeO2, MgO and CeMg12 intermetallic phases in different types and sizes. Further, these particles are responsible for improved mechanical properties. The findings are supported by the contribution of different strengthening mechanisms.

Significance of neutrophil microparticles in ischaemia-reperfusion: Pro-inflammatory effectors of endothelial senescence and vascular dysfunction.

Endothelial senescence is an emerging cause of vascular dysfunction. Because microparticles are effectors of endothelial inflammation and vascular injury after ischaemia‐reperfusion, we examined leucocyte‐derived microparticles of spleen origin as possible contributors. Microparticles were generated from primary rat splenocytes by either lipopolysaccharide or phorbol‐myristate‐acetate/calcium ionophore, under conditions mimicking innate and adaptive immune responses. Incubation of primary porcine coronary endothelial cells with either type of microparticles, but not with those from unstimulated splenocytes, leads to a similar threefold raise in senescence‐associated β‐galactosidase activity within 48 hours, indicating accelerated senescence, to endothelial oxidative stress, and a fivefold and threefold increase in p21 and p16 senescence markers after 24 hours. After 12‐hour incubation, the endothelial‐dependent relaxation of coronary artery rings was reduced by 50%, at distinct optimal microparticle concentration. In vitro, microparticles were pro‐thrombotic by up‐regulating the local angiotensin system, by prompting tissue factor activity and a secondary generation of pro‐coagulant endothelial microparticles. They initiated an early pro‐inflammatory response by inducing phosphorylation of NF‐κB, MAP kinases and Akt after 1 hour, and up‐regulated VCAM‐1 and ICAM‐1 at 24 hours. Accordingly, VCAM‐1 and COX‐2 were also up‐regulated in the coronary artery endothelium and eNOS down‐regulated. Lipopolysaccharide specifically favoured the shedding of neutrophil‐ and monocyte‐derived microparticles. A 80% immuno‐depletion of neutrophil microparticles reduced endothelial senescence by 55%, indicating a key role. Altogether, data suggest that microparticles from activated splenocytes prompt early pro‐inflammatory, pro‐coagulant and pro‐senescent responses in endothelial cells through redox‐sensitive pathways. The control of neutrophil shedding could preserve the endothelium at site of ischaemia‐reperfusion–driven inflammation and delay its dysfunction.

Extracts of ThaiPerilla frutescensnutlets attenuate tumour necrosis factor-α-activated generation of microparticles, ICAM-1 and IL-6 in human endothelial cells

Elevation of endothelial microparticles (EMPs) play an important role in the progression of inflammation-related vascular diseases such as cardiovascular diseases (CVDs). Thai perilla (Perilla frutescens) nutlets are rich in phenolic compounds and flavonoids that exert potent antioxidant and anti-inflammatory effects. We found that the ethyl acetate (EA) and ethanol (Eth) extracts of Thai perilla nutlets contain phenolic compounds such as luteolin, apigenin, chryseoriol and their glycosides, which exhibit antioxidant activity. The goal of the present study was to investigate the effects of the extracts on endothelial activation and EMPs generation in tumour necrosis factor-α (TNF-α)-induced EA.hy926 cells. We found that TNF-α (10 ng/ml) activated EA.hy926 cells and subsequently generated EMPs. Pre-treatment with the extracts significantly attenuated endothelial activation by decreasing the expression of the intracellular adhesion molecule-1 (ICAM-1) in a dose-dependent manner. Only the Eth extract showed protective effects against overproduction of interleukin-6 (IL-6) in the activated cells. Furthermore, the extracts significantly reduced TNF-α-enhanced EMPs generation in a dose-dependent manner. In conclusion, Thai perilla nutlet extracts, especially the Eth extract, may have potential to protect endothelium against vascular inflammation through the inhibition of endothelial activation and the generation of endothelial microparticles (EMPs).

Solid Solubilities of Sulfonamides and Use of Rapid Expansion of Supercritical Solutions for Microparticle Production

AbstractThe solubility of solid active pharmaceutical ingredients in supercritical fluids is a major thermodynamic criterion for selection and screening of microparticle generation processes. To develop an efficient method for solubility prediction, a solution model was adopted to establish the correlations of the solid solubilities of six sulfonamides in supercritical CO2. The model was capable of determining solubility correlations. Accordingly, it was attempted to simplify and generalize the model, yielding a predictive solution model, which provided order‐consistent solubility predictions. A case study for model extrapolation was conducted. After understanding the mechanisms underlying the solubility of sulfonamides, the rapid expansion of supercritical solutions (RESS) process was applied to produce microparticles of p‐toluenesulfonamide, an anticancer drug. The effects of RESS process parameters were investigated.

Yin and Yang of MCS-Related Coagulopathy: Shear Stress Promotes Platelet Prothrombosis and Microparticle Generation While Inducing Integrin Downregulation and Decreased Aggregability

Mechanical circulatory support (MCS) has emerged as a lifesaving therapy for patients with advanced and end-stage heart failure. Sadly, MCS therapy is limited by a paradoxical coagulopathy accompanied by both thrombosis and bleeding. We hypothesized that shear-mediated alterations of platelet hemostatic function, i.e. integrin expression, procoagulant activity, and aggregation, mechanistically drive MCS-related coagulopathy. Human platelets were exposed to shear stress in a hemodynamic shearing device (30-70 dyn/cm2, 10 min). Integrin αIIbβ3 & GPIb surface expression/activation, phosphatidylserine externalization (PSE) and microparticles (MPs) were quantified by flow cytometry. Platelet procoagulant activity was verified by thrombin generation assay. Platelet aggregation was measured by optical aggregometry. Shear stress exposure induced notable PSE, simultaneously promoting thrombin generation on platelets and MP. Paradoxically, shear-mediated platelet activation (SMPA) did not induce integrin αIIbβ3 activation. Moreover, high shear (70 dyn/cm2) prevented activation and upregulation of αII2bβ3 mediated by biochemical agonists. Aggregometry findings further validate flow cytometry results, as high shear did not promote aggregation, rather decreased ADP- and TRAP-6 induced aggregation. Likewise, SMPA led to the evident reduction of GPIb surface expression, as indicated by significant drop of GPIb+ platelet number and their fluorescence intensity (73.5 ± 2.9% & 953.1 ± 101.0 AU vs. 94.3 ± 0.7% & 1620 ± 72.4 AU for intact platelets; M ± SEM, ANOVA, p ≤ 0.05). Shear-mediated decrease of GPIb expression along with evident augmentation of GPIb- & αIIbβ3-positive MPs (3.3 ± 0.6% & 12.5 ± 2.8%, respectively) supports integrin shedding as an operative mechanism. SMPA promotes platelet PSE and procoagulant MP generation, thus facilitating thrombin formation and driving prothrombosis. Yet, shear stress did not promote platelet aggregation, rather impaired agonist-induced platelet aggregation via integrin αIIbβ3 and GPIb shedding from the platelets into MPs. This dichotomic effect of shear on platelets mechanistically defines the paradoxical prothrombotic state with a concomitant propensity of bleeding in MCS patients.

Impact of high mechanical shear stress and oxygenator membrane surface on blood damage relevant to thrombosis and bleeding in a pediatric ECMO circuit.

The roles of the large membrane surface of the oxygenator and the high mechanical shear stress (HMSS) of the pump in the extracorporeal membrane oxygenation (ECMO) circuit were examined under a pediatric support setting. A clinical centrifugal pump and a pediatric oxygenator were used to construct the ECMO circuit. An identical circuit without the oxygenator was constructed for comparison. Fresh human blood was circulated in the two circuits for 4 hours under the identical pump speed and flow. Blood samples were collected hourly for blood damage assessment, including platelet activation, generation of platelet-derived microparticles (PDMP), losses of key platelet hemostasis receptors (glycoprotein (GP) Ibα (GPIbα) and GPVI), and high molecular weight multimers (HMWM) of von Willebrand factor (VWF) and plasma free hemoglobin (PFH). Platelet adhesion on fibrinogen, VWF, and collagen was further examined. The levels of platelet activation and generation of PDMP and PFH exhibited an increasing trend with circulation time while the expression levels of GPIbα and GPVI receptors on the platelet surface decreased. Correspondingly, the platelets in the blood samples exhibited increased adhesion capacity to fibrinogen and decreased adhesion capacities on VWF and collagen with circulation time. Loss of HMWM of VWF occurred in both circuits. No statistically significant differences were found in all the measured parameters for blood damage and platelet adhesion function between the two circuits. The results indicate that HMSS from the pump played a dominant role in blood damage associated with ECMO and the impact of the large surface of the oxygenator on blood damage was insignificant.

On-chip generation of microcapsules in the presence of applied electric fields

Here, we present a complete on-chip technique for the generation of microparticles and microcapsules through chemical gelation in the presence of electric fields. A hybrid glass-PDMS (polydimethylsiloxane) microfluidic device acts as a single platform for application of electric fields to generate single/double emulsions, followed by their chemical gelation using an interface (liquid–liquid) based approach. Using this method, we have generated uniformly sized alginate microparticles and alginate microcapsules with a liquid core. We identify the flow rates required for establishing a stable liquid–liquid interface and characterize the effect of electric fields on droplet sizes of various systems. We also demonstrate significant size reduction of the particles compared to non-EHD (electrohydrodynamics) approaches and low polydispersity compared to existing external EHD-based methods. It is expected that the technique presented here will open up new strategies for combining the control provided by microfluidics with the size reduction possible with EHD, for a host of biomaterials.

Polyphenols: Modulators of Platelet Function and Platelet Microparticle Generation?

Platelets and platelet microparticles (PMPs) play a key role in the pathophysiology of vascular disorders such as coronary artery disease and stroke. In atherosclerosis, for example, the disruption of the plaque exposes endogenous agonists such as collagen, which activates platelets. Platelet hyper-activation and the high levels of PMPs generated in such situations pose a thrombotic risk that can lead to strokes or myocardial infarctions. Interestingly, dietary polyphenols are gaining much attention due to their potential to mimic the antiplatelet activity of treatment drugs such as aspirin and clopidogrel that target the glycoprotein VI (GPVI)–collagen and cyclooxygenease-1 (COX-1)–thromboxane platelet activation pathways respectively. Platelet function tests such as aggregometry and flow cytometry used to monitor the efficacy of antiplatelet drugs can also be used to assess the antiplatelet potential of dietary polyphenols. Despite the low bioavailability of polyphenols, several in vitro and dietary intervention studies have reported antiplatelet effects of polyphenols. This review presents a summary of platelet function in terms of aggregation, secretion, activation marker expression, and PMP release. Furthermore, the review will critically evaluate studies demonstrating the impact of polyphenols on aggregation and PMP release.

Phospholipid-Coated Hydrophobic Mesoporous Silica Nanoparticles Enhance Thrombectomy by High-Intensity Focused Ultrasound with Low Production of Embolism-Inducing Clot Debris.

Here we report the efficacy of a nanoparticle-assisted high-intensity focused ultrasound (HIFU) treatment that selectively destroys blood clots while minimizing generation of microparticles, or microemboli, that can cause further complications postsurgery. Treatment of malignant blood clots (thrombi) and the resulting emboli are critical problems for numerous patients, and treatments addressing these conditions would benefit from advancements in noninvasive procedures such as HIFU. While recanalization of occlusive blood clots is currently addressed with surgical intervention that seeks to minimize formation of large emboli, there is a danger of microemboli (micrometer-size particles) that have been theorized to be responsible for the poor correlation between apparent surgical success and patient outcome. Here, the addition of phospholipid-coated hydrophobically modified silica nanoparticles (P@hMSNs) improved the efficacy of HIFU treatment by serving as cavitation nuclei for mechanical disruption of thrombi. This treatment was evaluated for the ability to clear the HIFU focal area of a thick and dense thrombus within 10 min. Moreover, it was found that the use of P@hMSN+HIFU treatment generated a significantly smaller microembolic load as compared to comparison techniques, including a HIFU + microbubble contrast agent, HIFU alone, and direct mechanical disruption. This reduction in the microembolic load can occur either with primary removal of the clot by P@hMSN+HIFU or by insonation of the clot fragments after mechanical thrombectomy. Lastly, this method was evaluated in a flow model, where nonocclusive model thrombi and model emboli were mechanically ablated within the focal area within 15 s. Together, these results represent a combination therapy capable of resolving thrombi and microembolisms resulting from thrombectomy through localized destruction of clotted material.

Tiotropium inhibits proinflammatory microparticle generation by human bronchial and endothelial cells

Tiotropium is a muscarinic antagonist that reduces the risk of acute exacerbations of chronic obstructive pulmonary disease, possibly through an as yet incompletely characterized anti-inflammatory activity. We hypothesized that muscarinic activation of bronchial epithelial cells and endothelial cells causes the release of proinflammatory microparticles and that tiotropium inhibits the phenomenon. Microparticle generation was assessed by a functional assay, by flow cytometry and by NanoSight technology. Immortalized bronchial epithelial cells (16HBE) and umbilical vein endothelial cells were treated with acetylcholine in the presence of varying concentrations of tiotropium. Intracellular calcium concentration, extracellular regulated kinase phosphorylation and chemokine content in the conditioned media were assessed by commercial kits. Acetylcholine causes microparticle generation that is completely inhibited by tiotropium (50 pM). Microparticles generated by acetylcholine-stimulated cells increase the synthesis of proinflammatory mediators in an autocrine fashion. Acetylcholine-induced upregulation of microparticle generation is inhibited by an inhibitor of extracellular regulated kinase phosphorylation and by a phospholipase C inhibitor. Tiotropium blocks both extracellular regulated kinase phosphorylation and calcium mobilization, consistent with the hypothesis that the drug prevents microparticle generation through inhibition of these critical pathways. These results might contribute to explain the effect of tiotropium in reducing acute exacerbations of chronic obstructive pulmonary disease.

Generation of 3D Microparticles in Microchannels with Non-rectangular Cross Sections

Flow lithography in a conventional rectangular microchannel is limited to fabrication of particles for which only the shapes of top perimeters are controlled. We present a flow lithography technique for fabrication of microparticles of diverse 3D shapes and multiple layers using non-rectangular microchannels with designed cross sections that allow the creation of complex shapes and diverse cross-sectional shapes. Variations in cross-sectional shape allow high-throughput, on-demand production of microparticles in unconventional shapes such as tetrahedrons and pyramids. Multilayered 3D particles were generated in an enlarging triangular channel combined with on-chip PDMS valves, which allow particle alignment and fluid exchange. These 3D microparticles are expected to further expand the wide variety of applications of microparticles, especially in drug delivery and tissue engineering fields.

The Human Platelet as an Innate Immune Cell: Interactions Between Activated Platelets and the Complement System.

Platelets play an essential role in maintaining homeostasis in the circulatory system after an injury by forming a platelet thrombus, but they also occupy a central node in the intravascular innate immune system. This concept is supported by their extensive interactions with immune cells and the cascade systems of the blood. In this review we discuss the close relationship between platelets and the complement system and the role of these interactions during thromboinflammation. Platelets are protected from complement-mediated damage by soluble and membrane-expressed complement regulators, but they bind several complement components on their surfaces and trigger complement activation in the fluid phase. Furthermore, localized complement activation may enhance the procoagulant responses of platelets through the generation of procoagulant microparticles by insertion of sublytic amounts of C5b9 into the platelet membrane. We also highlight the role of post-translational protein modifications in regulating the complement system and the critical role of platelets in driving these reactions. In particular, modification of disulfide bonds by thiol isomerases and protein phosphorylation by extracellular kinases have emerged as important mechanisms to fine-tune complement activity in the platelet microenvironment. Lastly, we describe disorders with perturbed complement activation where part of the clinical presentation includes uncontrolled platelet activation that results in thrombocytopenia, and illustrate how complement-targeting drugs are alleviating the prothrombotic phenotype in these patients. Based on these clinical observations, we discuss the role of limited complement activation in enhancing platelet activation and consider how these drugs may provide opportunities for further dissecting the complex interactions between complement and platelets.

Surface modification of polyvinylidene fluoride membrane for enhanced wetting resistance

Abstract Modifications of polyvinylidene fluoride (PVDF) membranes were carried out to improve both hydrophobicity and stability through four steps: pore expansion by a plasma treatment, hydroxylation of the membrane by the Fenton reaction, generation and growth of microparticles (MPs) on the hydroxylated functional groups in pores, and hydrophobic modification. The membranes modified by the methods proposed in this study did not lose their hydrophobicity and maintained the flux over a significantly longer period. The PVDF membrane modified by hydrophobic MPs attached inside enlarged pores exhibited a minimized flux reduction and significantly higher antiwetting stability.

The emerging roles of eryptosis in liver diseases.

Erythrocytes undergo programmed cell death, similar to apoptosis, known as eryptosis. This process is a result of several factors including hyperosmolarity, oxidative stress, and exposure to xenobiotics, and is characterized by the breakdown of membrane phospholipid asymmetry, the clustering of band 3, and the generation of red blood cell-derived microparticles. Under pathological conditions, the liver is the primary site of erythrocyte clearance and plays an important role in iron recycling. Phosphatidylserine exposure and band-3 clustering on eryptotic erythrocytes represent mainly pro-phagocytic signals. Further, the percentage of eryptotic erythrocytes is enhanced in the circulating blood of patients with hepatic failure, hyperbilirubinemia, and nonalcoholic steatohepatitis. In this review, we concentrate on recent progress regarding the pathophysiological roles of eryptosis in liver diseases.

Generation of platelet-derived microparticles through the activation of the toll-like receptor 4

IntroductionInfection from different bacterial may increase the risk of thrombosis and atherosclerosis risk by production and secretion of many proinflammatory factors. Human platelets have toll-like receptor 4 (TLR4), the principal receptor for lipopolysaccharide (LPS). The activation of platelet produces Platelet-derived Microparticles (PDMPs) measuring less than 1.0 micron (that are very abundant in circulation >90%), which are associated with the development of Cardiovascular Diseases (CVDs), the leading cause of death in the world. ObjectivesExperiments were designed to evaluate the generation of pro-thrombogenic microparticles in vitro on platelets via TLR4 activation. MethodsPlatelet-rich plasma and washed platelets from healthy volunteers were incubated for the generation of PDMPs. The best source for the generation of microparticles was washed platelets. Then the washed platelets were incubated for 15 minutes with ultrapure Escherichia coli LPS (0–9 μg/mL) followed by activation with ADP (1 μM, subaggregant concentration), centrifuged for 60 minutes and analyzed by flow cytometry. ResultsIncubating platelets with LPS (9 μg/mL) and ADP (1 μM) produced a 34-fold increase in PDMPs generation. Finally, we evaluated this protocol to detect the inhibition of PDMPs generation, washed platelets were incubated with acetylsalicylic acid (10 μM) and an inhibition of 7.7-fold in PDMPs generation for activation of TLR4 was found. ConclusionA new and easy protocol for PDMPs generation and analysis by Flow Cytometry is established. In the future it could be used to determine the association of PDMPs with different pathologies.

P2Y12 Receptor Antagonists: Do They Really Inhibit Shear-Mediated Platelet Activation within MCS?

Purpose Shear-mediated platelet activation (SMPA) by supra-physiological blood flow found within MCS is a main driver and contributor of device-related thrombosis. Thus, antiplatelet drugs targeting the main pathways of platelet activation are routinely prescribed. We have shown, that aspirin and GP IIbIIIa blockers have limited ability in mitigating SMPA, and do NOT protect platelets from integrin shedding and microparticle (MP) generation. In contrast, ticagrelor, a direct P2Y12 purinergic receptor antagonist, drastically inhibits platelet prothrombinase activity induced by high shear. The aim of the study was to define the role of the P2Y12 pathway in SMPA and evaluate the effect of P2Y12 antagonists on platelet procoagulant activity and MP generation induced by high shear stress. Methods The following P2Y12 antagonists were used: clopidogrel active metabolite (10 µM), cangrelor (1 µM) and ticagrelor (1 µM). After 10 min incubation with the agent, human platelets were exposed to continuous high shear stress (70 dyn/cm2, 10 min) in a hemodynamic shearing device. Platelet procoagulant activity was assessed using the annexin V binding assay, detecting procoagulant surface exposure, and platelet activity state (PAS) assay measuring thrombin generation. MPs were quantified by flow cytometry as CD41+/AnV+ particles distinguished from platelets by their FS/SS. Results Ticagrelor and cangrelor showed similar inhibitory effect, consistently decreasing both platelet procoagulant activity and microparticle generation induced by shear stress. The number of AnV+ platelets, AnV+ MPs, and PAS levels were decreased by 26%, 27%, and 30%, respectively, as compared with non-treated controls subjected to shear. Clopidogrel active metabolite, known for its low affinity to the targeted receptor, reduced PAS by 15%, while annexin V binding was diminished in more than 10 times for platelets and 2 times for MPs, indicating a significant reduction of platelet procoagulant surface exposure but limited inhibition of thrombin generation. Conclusion P2Y12 purinergic receptor antagonists inhibit shear-mediated platelet procoagulant surface formation and microparticle generation, both contributors in overall platelet prothrombotic activity induced by high shear stress within MCS. Our results suggest that P2Y12 pathway is involved in the regulation of SMPA.

Insight into the complex pathophysiology of sickle cell anaemia and possible treatment.

Sickle cell anaemia (SCA) is the consequence of abnormal haemoglobin production due to an inherited point mutation in the β-globin gene. The resulting haemoglobin tetramer is poorly soluble when deoxygenated, and when this is prolonged, intracellular gelation of sickle haemoglobin occurs, followed by haemoglobin polymerisation. If many cycles of sickling and unsickling occur, the red cell membrane will be disrupted leading to haemolysis and vaso-occlusive events. Recent studies have also shown that leucocyte adhesion molecules and nitric oxide (NO) depletion are involved in endothelial damage. New insights in SCA pathophysiology and vascular biology have shown that cell-derived microparticle (MP) generation is also involved in the vaso-occlusion. Endothelial damage is perpetuated by impaired production or increased consumption of protective modulators such as protein C, protein S and NO. New therapeutic interventions should address these aspects of SCA pathogenesis. To date, the only US-FDA-approved therapy to prevent painful vaso-occulsive episodes is hydroxyurea that reduces haemoglobin polymerisation in sickle cells by increasing the production of foetal haemoglobin and L-glutamine. However, several new drugs have been tested in the last years in randomised clinical trials. We here report an update on the current status of knowledge on SCA.

Artificial shear stress effects on leukocytes at a biomaterial interface.

Medical devices, such as ventricular assist devices (VADs), introduce both foreign materials and artificial shear stress to the circulatory system. The effects these have on leukocytes and the immune response are not well understood. Understanding how these two elements combine to affect leukocytes may reveal why some patients are susceptible to recurrent device-related infections and provide insight into the development of pump thrombosis. Biomaterials-DLC: diamond-like carbon-coated stainless steel; Sap: single-crystal sapphire; and Ti: titanium alloy (Ti6 Al4 V) were attached to the parallel plates of a rheometer. Whole human blood was left between the two discs for 5minutes at +37°C with or without the application of shear stress (0s-1 or 1000s-1 ). Blood was removed and used for complete blood cell counts, flow cytometry (leukocyte activation, cell death, microparticle generation, phagocytic ability, and reactive oxygen species [ROS] production), and the production of pro-inflammatory cytokines. L-selectin expression on monocytes was decreased when blood was exposed to the biomaterials both with and without shear. Applying shear stress to blood on a Sap and Ti surface led to activation of neutrophils shown as decreased L-selectin expression. Sap and Ti blunted the LPS-stimulated macrophage migration inhibitory factor (MIF) production, most notably when sheared on Ti. The biomaterials used here have been shown to activate leukocytes in a static environment. The introduction of shear appears to exacerbate this activation. Interestingly, a widely accepted biocompatible material (Ti) utilized in many different types of devices has the capacity for immune cell activation and inhibition of MIF secretion when combined with shear stress. These findings contribute to our understanding of the contribution of biomaterials and shear stress to recurrent infections and vulnerability to sepsis in some VAD patients as well as pump thrombosis.

Continuous magnetic droplets and microfluidics: generation, manipulation, synthesis and detection.

In this review, an introduction is given to provide the fundamental principles of magnetic droplet microfluidics. This is followed by a thorough discussion of methods that have been developed for the continuous generation of magnetic droplets and their controlled and precise manipulation by using external magnetic fields. Next, attention is given to techniques devised for the continuous fabrication of magnetic materials in droplets with an emphasis on the synthesis and modification of magnetic nanoparticles (MNPs), magnetic microstructures, Janus microparticles and magnetic hydrogels. In addition, selected applications of continuous magnetic droplets in (bio)assays and detection methods are discussed. The review (with 113 refs.) ends with concluding remarks and a discussion of current challenges and the future outlook for the field of continuousmagnetic droplet microfluidics. Graphical abstract Continuous generation of magnetic droplets in microfluidic devices has the advantage of producing droplets at high frequencies and therefore has been exploited for the synthesis and generation of magnetic microparticles, manipulation, performing (bio)assyas and detection of magnetic contents.

Generation of α-Linolenic Acid Ethyl Ester Microparticles from Silkworm Pupae Oil by Microfluidic Droplet

The instability of polyunsaturated fatty acids to peroxidation often hinders the practical application of oil-based products, and oil-in-water (o/w) emulsions are important components of a wide range of drugs, functional foods and consumer care products. Caffeic acid (CA)-grafted chitosan (CA-g-Ch) was successfully synthesized as a novel wall material and used to embed α-linolenic acid ethyl ester (ALAEE) using microfluidic droplet technology. The results indicated that CA-g-Ch has lower viscosity and stronger emulsification properties than chitosan, and its solution is a Newtonian fluid with good fluidity. When the flow rates of the disperse phase and continuous phase were 0.45 µL/min and 0.75 µL/min, the diameter of the droplets prepared with a 0.25% concentration of Tween 20 was 29 µm, and the droplets had obvious monodispersity. In addition, the droplets were difficult to form normally when the concentration was higher than 1%. The ALAEE microcapsules were easily prepared using freeze-dried droplets. The antioxidant activity of ALAEE microcapsules measured by the DPPH method was 84.96%, which was 7.06 times higher than that observed for untreated ALAEE. Therefore, the monodisperse ALAEE-M prepared by microfluidic microdroplet technology combined with antioxidant wall materials has successfully improved the antioxidant properties of core materials, showing promise for food or drug applications.