Microparticle Formation Research Articles

Sustainable Tailoring of Lignin Nanoparticles Assisted by Green Solvents

AbstractThis work aimed at studying the self‐assembly of lignin macromolecules towards lignin nanoparticles (LNPs) with green solvents and shedding light on a tailor‐made production of LNPs through a meticulous study of different variables. The methodology (antisolvent to lignin solution – method A; or lignin solution to antisolvent – method B), the lignin solvent, the flow rate of solvent/antisolvent addition, the lignin solution loading and the washing step (centrifugation vs dialysis) were examined. Remarkably, method B enabled achieving desired LNPs (127.4–264.9 nm), while method A induced the formation of lignin microparticles (582.8–7820 nm). Among lignin solvents, ethanol allowed the preparation of LNPs with the lowest hydrodynamic diameter (method B=127.4 nm), while the largest particles (method A=7820 nm) were obtained with ethylene glycol. These latest particles were characterized as heterogeneous, irregular, and highly aggregated when compared for instance with γ‐valerolactone counterparts, which showed the most homogeneous (PDI=0.057–0.077) and spherical particles. Moreover, decreasing lignin solution loading enabled the reduction on LNP size and Zeta potential. Dialysed samples allowed the formation of LNPs with lower hydrodynamic size, reduced aggregation, and higher homogeneity. Furthermore, dialysis provided high stability to LNPs, avoiding particle coalescent phenomenon.

Microfluidic extensional flow device to study mass transfer dynamics in the polymer microparticle formation process.

Polymer microparticles are often used to encapsulate drugs for sustained drug-release treatments. One of the ways they are manufactured is by using a solvent extraction process, in which the polymer solution is emulsified into an aqueous bulk phase using a surfactant as a stabilizing agent, followed by the removal of the solvent. The radius of a polymer drop decreases as a function of time until the polymer reaches the gelling point, after which it is separated and dried. Among the various operating parameters, the rate of solvent extraction is a critical step that affects the morphology and porosity, and consequently, the kinetics of drug release. But a fundamental mechanistic understanding of the solvent extraction dynamics as a function of shear is still unexplored. In this study, we have developed an experimental mass transfer model to predict the extraction by using the microfluidic extensional flow device (MEFD) to probe the shear and extraction dynamics at the level of a single drop in a linear extensional flow field. We used a computer-controlled feedback algorithm to manipulate the flow field and hydrodynamically trap a Hele-Shaw drop and observe the extraction process. For the polymer solution, we used a biocompatible polymer, poly-lactic-co-glycolic acid (PLGA) with ethyl acetate (EtOAc) as the solvent. Our experiments were conducted by varying the extensional rate (G) in the channel from ∼0.1 s-1 to ∼10 s-1, and using an analytical solution of the flow field, we captured the dissolution process and measured the change in drop radius (R) with time (t). Interestingly, we initially observed a short-time asymptote R ∼ t, and later the long-time asymptote of R = constant; both trends were physically explained. The transport model developed in this work can be used to predict extraction rates and polymer microparticle composition for any polymer-solvent system. This work is also an important contribution to the literature on convective mass transfer in partially miscible emulsions.

Cricket Flour and Pullulan Microparticle Formation <i>via</i> Electro-Blow Spinning as a New Method for the Protection of Antioxidant Compounds from Fruit Extracts

Cricket Flour and Pullulan Microparticle Formation <i>via</i> Electro-Blow Spinning as a New Method for the Protection of Antioxidant Compounds from Fruit Extracts

Role of protease-activated receptor 4 in mouse models of acute and chronic kidney injury.

Protease-activated receptor 4 (PAR4) is a G protein-coupled receptor activated by thrombin. In the platelet, response to thrombin PAR4 contributes to the predominant procoagulant microparticle formation, increased fibrin deposition, and initiation of platelet-stimulated inflammation. In addition, PAR4 is expressed in other cell types, including endothelial cells. Under inflammatory conditions, PAR4 is overexpressed via epigenetic demethylation of the PAR4 gene, F2RL3. PAR4 knockout (KO) studies have determined a role for PAR4 in ischemia-reperfusion injury in the brain, and PAR4 KO mice display normal cardiac function but present less myocyte death and cardiac dysfunction in response to acute myocardial infarction. Although PAR4 has been reported to be expressed within the kidney, the contribution of PAR4 to acute kidney injury (AKI) and chronic kidney disease (CKD) is not well understood. Here we report that PAR4 KO mice are protected against kidney injury in two mouse models. First, PAR4 KO mice are protected against induction of markers of both fibrosis and inflammation in two different models of kidney injury: 1) 7 days following unilateral ureter obstruction (UUO) and 2) an AKI-CKD model of ischemia-reperfusion followed by 8 days of contralateral nephrectomy. We further show that PAR4 expression in the kidney is low in the control mouse kidney but induced over time following UUO. PAR4 KO mice are protected against blood urea nitrogen (BUN) and glomerular filtration rate (GFR) kidney function pathologies in the AKI-CKD model. Following the AKI-CKD model, PAR4 is expressed in the collecting duct colocalizing with Dolichos biflorus agglutinin (DBA), but not in the proximal tubule with Lotus tetragonolobus lectin (LTL). Collectively, the results reported in this study implicate PAR4 as contributing to the pathology in mouse models of acute and chronic kidney injury.NEW & NOTEWORTHY The contribution of the thrombin receptor protease-activated receptor 4 (PAR4) to acute kidney injury (AKI) and chronic kidney disease (CKD) is not well understood. Here we report that PAR4 expression is upregulated after kidney injury and PAR4 knockout (KO) mice are protected against fibrosis following kidney injury in two mouse models. First, PAR4 KO mice are protected against unilateral ureter obstruction. Second, PAR4 KO mice are protected against an AKI-CKD model of ischemia-reperfusion followed by contralateral nephrectomy.

Investigation of physicochemical and biological properties of bacterial cellulose & zein-reinforced edible nanocomposites based on flaxseed mucilage containing Origanum vulgare L. essential oil

In the present study, the effect of zein and different amounts of bacterial cellulose (BC; 1, 2 and 3 wt%) on the physical, mechanical and barrier properties of flaxseed mucilage/carboxymethyl cellulose (FM/CMC) composite was investigated. The appearance of the absorption band at 1320cm−1 in the ATR-FTIR spectra of nanocomposites indicated the successful introduction of zein into their structure. The characteristic peak at 2θ of 9° belonging to zein disappeared in XRD patterns of the prepared composites suggesting the successful coating of zein via hydrogen bonding interactions. SEM images proved the formation of semi-spherical zein microparticles in the FM/CMC matrix. TGA plots ascertained the addition of zein and nanocellulose caused a significant increase in the thermal stability of FM/CMC film, although zein showed a greater effect. The presence of zein and nanocellulose increased the mechanical strength of nanocomposites. The WVP of FM/CMC decreased after the incorporation of zein and nanocellulose, which created a tortuous path for the diffusion of water molecules. The zein particles exhibited a greater influence on improving the mechanical and barrier properties compared to nanocellulose. FM/CMC-Z film exhibited the highest mechanical strength (49.07 ± 5.89 MPa) and the lowest WVP (1.179 ± 0.076). The composites containing oregano essential oil (EO) showed higher than 60 % antibacterial properties. The bactericidal efficiency of FM/CMC/Z-EO and FM/CMC/Z-EO/BC1 nanocomposites decreased about 10% compared to FM/CMC/EO and FM/CMC-Z/BC1. This evidenced the successful encapsulation of EO molecules in zein particles. According to the in vitro release study, entrapment of EO into zein particles could delay the release and provide the extended antimicrobial effect.

Blebbing of the plasma membrane of lymphocytes as a marker of endothelial dysfunction in the development of post-resection insufficiency in patients with focal liver lesions

Purpose of the study. To evaluate the intensity of blebbing of the plasma membrane of lymphocytes and the formation of microparticles of lymphocytic origin in patients with postresection hepatic failure. Material and methods. The study involved 54 patients with focal liver diseases. The study involved 32 (59%) women, 22 (41%) men. The average age was 59.5 [49.75; 66,00]. Patients were divided into groups, 1 group - 10 patients with developed acute liver failure and 2 group - 44 patients with a favorable course of postoperative period. The following surgical interventions were performed: 36 (67%) patients underwent surgery - laparotomy, segmental liver resection, 10 (18%) - left-sided hemihepatectomy and 8 (15%) - right-sided hemihepatectomy. Results. Predictors of early postoperative hepatic failure are a decrease in initial blebbing and an increase in terminal blebbing and free microparticles of lymphocytic origin. Conclusions. Thus, changes in lymphocyte blebbing and the presence of free microparticles of lymphocytic origin are due to the development of endothelial insufficiency and apoptosis of lymphocytes in the context of liver failure and are determined by the reduced function of residual liver volume.

ENVIRONMENTAL POLLUTION AND IMPACT OF HIGHWAYS DURING OPERATION

The current state and rapid development of road construction and transport infrastructure are the reasons for the increase in environmental pollution, especially in the immediate vicinity of highways. Roadside areas accumulate a large amount of pollutants which leads to changes in soil properties and comprehensive degradation of landscapes. Together with the road runoff, pollutants enter the lakes and the rivers and cause significant damage to aquatic flora and fauna. During the operation of highways, a large amount of exhaust gases, oil products, heavy metals, and dust enters the natural environment. Currently, in Ukraine, most studies are aimed at reducing the negative impact of exhaust gases on the atmosphere, oil pollution of soils and the aquatic environment. Unlike in the European countries, the research on the formation of microparticles which, together with dust and surface runoff contaminate soils, surface and groundwater of roadside areas has not been conducted at all. This paper analyzes the European research experience on the negative impact of microparticles on the environment. The components of microparticles - micropollutants formed as a result of the interaction of vehicles with the road surface (tire wear products, road dust, road markings, etc.) are presented. The paper also presents the sources of formation, qualitative and quantitative characteristics of the main micropollutants and their pathways in the roadside area. This will allow further developing the effective measures to reduce the formation and spread of micr

Preparation and characterization of NaF/Chitosan supramolecular complex and their effects on prevention of enamel demineralization

Fluoridated mouthrinse is indicated for individuals with high risk of caries. Chitosan (Chit) exhibits antibacterial properties, but little is known about its effects on enamel when combined with sodium fluoride (NaF) to form NaF/Chit supramolecular complexes. In our study, NaF/Chit supramolecular complexes structured as microparticles were synthetized and characterized, and their effects on human enamel were evaluated after cariogenic challenge simulating the daily mouthrinse use. Initially, NaF/Chit complex formation was investigated based on several titrations by measuring the zeta potential, electrical conductivity (κ), hydrodynamic diameter (Dh), viscosity (η) and heat flow (by isothermal titration calorimetry) against the molar ratio [NaF]/[Chitmonomer], which allowed us to identify the interactions between Chit-NaF with a stoichiometry of approximately 0.68. Spontaneous microparticle formation was observed. Samples of enamel blocks were prepared and divided into eight groups (n = 10/group): (i) 0.2% Chit; (ii) 0.2% NaF; (iii) 0.2% NaF/Chit suspension; (iv) 0.2% acetic acid; (v) 0.05% Chit; (vi) 0.05% NaF; (vii) 0.05% NaF/Chit suspension; and (viii) 0.05% acetic acid. Cariogenic challenge was performed in each sample by cycling in demineralization and remineralization solutions for 7 days. Before each demineralization cycle, the corresponding substances were passively applied daily for 90 s, even in groups with 0.02% concentration. After 7 days, samples were examined for Knoop hardness (KHN) measurements. The data were analyzed by repeated-measures ANOVA and Tukey tests (α = 0.05). The 0.2% NaF and 0.2% NaF/Chit groups showed higher KHNpost-challenge values than the other groups. The 0.2% NaF/Chit microparticle suspension reduced the enamel hardness loss after cariogenic challenge as effectively as the 0.2% NaF solution and demonstrated potential for use in a formulation with anti-caries effects.

SARS-CoV-2 spike protein induces endothelial inflammation via ACE2 independently of viral replication

COVID-19, caused by SARS-CoV-2, is a respiratory disease associated with inflammation and endotheliitis. Mechanisms underling inflammatory processes are unclear, but angiotensin converting enzyme 2 (ACE2), the receptor which binds the spike protein of SARS-CoV-2 may be important. Here we investigated whether spike protein binding to ACE2 induces inflammation in endothelial cells and determined the role of ACE2 in this process. Human endothelial cells were exposed to SARS-CoV-2 spike protein, S1 subunit (rS1p) and pro-inflammatory signaling and inflammatory mediators assessed. ACE2 was modulated pharmacologically and by siRNA. Endothelial cells were also exposed to SARS-CoV-2. rSP1 increased production of IL-6, MCP-1, ICAM-1 and PAI-1, and induced NFkB activation via ACE2 in endothelial cells. rS1p increased microparticle formation, a functional marker of endothelial injury. ACE2 interacting proteins involved in inflammation and RNA biology were identified in rS1p-treated cells. Neither ACE2 expression nor ACE2 enzymatic function were affected by rSP1. Endothelial cells exposed to SARS-CoV-2 virus did not exhibit viral replication. We demonstrate that rSP1 induces endothelial inflammation via ACE2 through processes that are independent of ACE2 enzymatic activity and viral replication. We define a novel role for ACE2 in COVID-19- associated endotheliitis.

Recent Progress of Droplet Microfluidic Emulsification Based Synthesis of Functional Microparticles.

The remarkable control function over the functional material formation process enabled by droplet microfluidic emulsification approaches can lead to the efficient and one-step encapsulation of active substances in microparticles, with the microparticle characteristics well regulated. In comparison to the conventional fabrication methods, droplet microfluidic technology can not only construct microparticles with various shapes, but also provide excellent templates, which enrich and expand the application fields of microparticles. For instance, intersection with disciplines in pharmacy, life sciences, and others, modifying the structure of microspheres and appending functional materials can be completed in the preparation of microparticles. The as-prepared polymer particles have great potential in a wide range of applications for chemical analysis, heavy metal adsorption, and detection. This review systematically introduces the devices and basic principles of particle preparation using droplet microfluidic technology and discusses the research of functional microparticle formation with high monodispersity, involving a plethora of types including spherical, nonspherical, and Janus type, as well as core-shell, hole-shell, and controllable multicompartment particles. Moreover, this review paper also exhibits a critical analysis of the current status and existing challenges, and outlook of the future development in the emerging fields has been discussed.

Production of betalain-rich Opuntia ficus-indica peel flour microparticles using spray-dryer: A holist approach

This study aimed to obtain a betalain-rich extract (BRE) from Opuntia ficus-indica peels and protect them through a holistic approach involving microencapsulation via spray-drying. To enhance the stability of the microencapsulated betalains, an antioxidant-rich extract (ARE) obtained through hydrothermal extraction from the residual material remaining after the conventional extraction of betalains was used as a stabilizer during the spray-drying process. The antioxidant activity of the ARE was evaluated by measuring its IC50 value for 2,2-Diphenyl-1-picrylhydrazyl (DPPH) of 65.8 μg/mL, its Trolox equivalent antioxidant capacity (TEAC) of 60.4 gTrolox eq./100 g, and its reducing power of 16.6 g butylated hydroxytoluene (BHT) eq./100 g. Spray-drying parameters were optimized using a Box-Behnken design to enhance the total betalain content and minimize by-product formation. The results demonstrated that the addition of the ARE significantly improved the stability of betalains during spray-drying, leading to the formation of microparticles with high betalain content and enhanced stability. The optimal conditions (0.72% starch, 1.50% BRE and 0.25% ARE) resulted in microparticles with a maximum concentration of 6.74 ± 0.09 mgBetalains/g. The predictive model exhibited high accuracy in estimating experimental values. This research provides a natural and sustainable solution for food coloring by effectively utilizing discarded Opuntia ficus-indica peel. Moreover, it offers new scientific understanding on the production of betalain-rich microparticles as a possible substitute for food coloring, with considerable benefits in terms of sustainability and high antioxidant capacity.

Preliminary assessment of influence of calcium alginate beads on the dissolution of meloxicam

The purpose of the study was to evaluate the preparation of alginate-based microparticles with meloxicam (MLX). A poorly soluble substance classified to BCS class II, it was chosen as a model substance. The ionotropic gelation was the process used for the formation of microparticles. The impact of the carrier on the dissolution of MLX from this formulation was also investigated. Study was realized in few steps: preparation of polymer particles containing suspended MLX in their structure; drying them in various conditions (room temperature, freeze drying); morphology characterization and then assessment of impact of polymer on dissolution of the model substance. Also, DDSolver software was used for checking the similarity of release profiles. Validated UV-Vis spectrophotometric method was used for MLX determination on different steps of work. As it showed, calcium alginate particles were successfully prepared with ionotropic gelation. The drying method of prepared particles has a substantial impact on the release profiles of meloxicam, and these formulations significantly improve the MLX release from this form of the delivery system.

Generation of Photopolymerized Microparticles Based on PEGDA Hydrogel Using T-Junction Microfluidic Devices: Effect of the Flow Rates.

The formation of microparticles (MPs) of biocompatible and biodegradable hydrogels such as polyethylene glycol diacrylate (PEGDA) utilizing microfluidic devices is an attractive option for entrapment and encapsulation of active principles and microorganisms. Our research group has presented in previous studies a formulation to produce these hydrogels with adequate physical and mechanical characteristics for their use in the formation of MPs. In this work, hydrogel MPs are formed based on PEGDA using a microfluidic device with a T-junction design, and the MPs become hydrogel through a system of photopolymerization. The diameters of the MPs are evaluated as a function of the hydrodynamic condition flow rates of the continuous (Qc) and disperse (Qd) phases, measured by optical microscopy, and characterized through scanning electron microscopy. As a result, the following behavior is found: the diameter is inversely proportional to the increase in flow in the continuous phase (Qc), and it has a significant statistical effect that is greater than that in the flow of the disperse phase (Qd). While the diameter of the MPs is proportional to Qd, it does not have a significant statistical effect on the intervals of flow studied. Additionally, the MPs' polydispersity index (PDI) was measured for each experimental hydrodynamic condition, and all values were smaller than 0.05, indicating high homogeneity in the MPs. The microparticles have the potential to entrap pharmaceuticals and microorganisms, with possible pharmacological and bioremediation applications.

Radiation induced graft polymerization of fluorinated monomers onto flax fabrics for the control of hydrophobic and oleophobic properties

Functional textiles have been one of the most studied topics in recent decades. Due to toxicity concerns, the treatment of fabrics for non-wettable properties with fluorinated molecules is nowadays limited to short fluoroalkyl chains. In this work, several fluorinated (meth)acrylic monomers such as 1,1,1,3,3,3-hexafluoroisopropyl methacrylate, 2-(perfluorobutyl)ethyl methacrylate, 1H,1H,2H,2H-perfluorooctyl methacrylate, 1H,1H,2H,2H-perfluorooctyl acrylate and 1H,1H,2H,2H-perfluorodecyl methacrylate (denoted as M2, M4, M6, AC6 and M8, respectively) were grafted onto flax fabrics to improve their hydrophobic and oleophobic properties by radiografting using a pre-irradiation procedure. The effects of the length of the fluoroalkyl group of the monomer, the irradiation dose and the reaction time on the grafting rate were studied. The functionalization of flax fabrics by these five monomers was confirmed by FTIR spectroscopy analysis. The morphology of the fibers before and after treatment was studied by scanning electron microscopy (SEM). The location of fluorine element in the flax elementary fibers was assessed by SEM-EDX. The hydro- and oleophobic properties were determined by contact angle measurement using water and diiodomethane as solvents, respectively. The sliding angle was also measured to assess the water repellency of hydrophobic fabrics. Significant fluorine contents were obtained for flax fibers irradiated and treated with 10 wt% solutions of monomer. Hydro- and oleophobic fabrics were obtained for flax irradiated even at a low dose of 5 kGy and treated with M4, with water and diiodomethane contact angles (CAs) of about 139° and 120°, respectively. Superhydrophobic fabrics (CA = 150°) were also achieved for samples irradiated at 20, 50 and 100 kGy and treated with 10 wt% of M8. For this monomer, SEM analysis showed the formation of spherical microparticles of fluoropolymer covering the surface of elementary fibers. The formation of these particles is assumed to result from a dispersion polymerization mechanism. This is due to the fewer affinity of M8 with methanol and to the incompatibility of the formed polymer chains with this solvent used for the grafting reaction.

Enhanced zT due to non-stoichiometric induced defects for bismuth telluride thermoelectric materials

Thermoelectric materials have potential applications in energy conversion and waste heat recovery. Thermoelectric materials with non-stoichiometric composition may exhibit improved thermoelectric properties compared to the stoichiometric composition material. Bi2Te3 is one of the best-known thermoelectric materials having optimum performance near room temperature. In the present study, non-stoichiometric bismuth telluride (Bi2±x Te3), x = (0, 0.01, 0.02, 0.03), was synthesized using the co-precipitate method to create imperfections and strains in the crystal structure of the material. The crystal structure of the synthesized bismuth telluride revealed significant changes in the c direction when examined using X-ray diffraction (XRD). Scanning electron microscopy (SEM) revealed the formation of micro-particles. Energy dispersive spectroscopy (EDX) also confirmed the non-stoichiometric elemental composition of Bi and Te rich bismuth telluride. Thermogravimetric analysis (TGA) was performed in a non-inert environment, and an oxidation temperature of 685 ​K was recorded in non-stoichiometric samples. The post-oxidation of stoichiometric and non-stoichiometric Bi Rich and Te Rich bismuth tellurides was also confirmed by XRD and TGA comparison. The thermal conductivity was reduced by the imperfections and defects for all non-stoichiometric compositions, and a zT value of 0.54 at 420 ​K was obtained in the Tellurium Rich bismuth telluride, which is about a 12% improvement compared to the pure sample.

Explorando el impacto del extracto de bellota en la calidad y sabor de las hamburguesas de carne de res

Protein microparticles are of interest in the development of low-fat foods as stabilizing agents and, for their production, it is important to consider the influence of the processing conditions on stability and size of particles. In the present study, the characteristics of microparticles of soy protein isolate (SPI) obtained by microfluidization (MF) (110 MPa and 3 MF cycles) of aggregates obtained by heat treatment (95 °C for 15 min) and different pH values (3 , 5, 7 and 9). The results of particle size, zeta potential and turbiscan stability index (TSI) showed that the least stable microparticles in suspension were obtained at pH 5, due to their proximity to the average isoelectric point of soy proteins (4.5). In contrast, the most stable microparticles in suspension were obtained at pH 9, presenting small particle sizes (398.35 ± 4.19nm) and a low TSI (0.8 ± 0.08). By means of atomic force microscopy (AFM) it was possible to observe the breakdown of the aggregates for the formation of microparticles during the microparticulation process. Surface roughness and image texture analyses allowed evaluating the effect of MF on the surface of the microparticles. The most relevant descriptor for the characterization of microparticlers was the second angular moment whereas contrast, correlation, inverse difference moment, entropy, and fractal dimension did not correlate with the characteristics of the images in the whole range of operating conditions given that their calculation algorithms are not sensitive enough to detect the small variations in roughness of the samples. The best conditions for production of microparticels were 3 cycles of MF and pH 9 which gave place to homogenous and stable systems.

Triglyceride mixtures: Cold-bursting and double emulsion formation

It was shown recently that a solid-to-solid phase transitions (α-to-β, gel-to-crystal), typical for many lipid substances, can lead to formation of nanoporous network inside lipid micro-particles dispersed in aqueous surfactant solutions (Cholakova et al. ACS Nano2020, 14, 8594). These nanopores are spontaneously infused by the aqueous phase when appropriate combination of water-soluble and oil-soluble surfactants is applied. As a result, the initial lipid micro-particles can spontaneously burst into much smaller nanoparticles, just by cooling and heating of the initial dispersion. Under certain conditions, the infused aqueous phase is entrapped in the moment of lipid particle melting and double emulsion of type water-in-oil-in-water (W/O/W) is formed. The current study aims to clarify how the composition of the lipid micro-drops and surfactants affect the observed phenomena. Selected mixtures of monoacid triglycerides are studied systematically. The results show that the bursting efficiency usually decreases when the complexity of the lipid mixture increases, due to the expanded temperature interval for lipid melting. Nevertheless, complete particle bursting and lipid nanoparticles with diameters down to 20 nm are formed even for the most complex lipid compositions under appropriate conditions. The key mechanisms leading to efficient fragmentation and double emulsion formation are clarified, and the main governing factors are explored. On this basis, we reveal that the system behavior can be switched between complete particle bursting and W/O/W emulsion formation by: (1) Change in the cooling and heating rates without any changes in the chemical composition, (2) Change in the concentration of oil-soluble surfactant, and/or (3) Change in the phase in which the oil-soluble surfactant is introduced initially. Thus, we have formulated guiding rules to control the formation of lipid nanoparticles and W/O/W emulsions with triglyceride mixtures promising multiple potential applications.

Serial Case: Infarct Stroke In Covid 19 Patients

Introduction: SARS-CoV-2 has been reported to cause various neurological symptoms including stroke. SARS-CoV-2 infection causes the release of cytokines, proinflammatory chemokines, immune system activation, coagulopathy, endothelium, vasculitis, hypoxia, renin-angiotensin system imbalance, and cardiovascular complications, all of which can contribute to stroke. Purpose: Describe the incidence of stroke with different conditions in COVID 19 Cases: There were two cases of stroke infarct in a COVID-19 patient who was admitted to our hospital. Both were treated with a diagnosis of stroke infarct with previous COVID-19 symptoms, the results of laboratory examinations revealed an increase in inflammatory markers in both patients and had been given appropriate treatment according to each patient's condition. But at the end of the treatment one patient died and the other patient went home with clinical improvement. Discussion: The incidence of stroke infarct in this case is thought to be due to several factors, namely the presence of comorbidities in the patient, microvascular thrombus due to the formation of neutrophil extracellular traps (NET), activation of complement which causes thrombogenesis and vasculopathy, formation of antiphospholipid antibodies so that protein c is reduced, the formation of microparticles causes platelet hyperactivation. and increased tissue factor (TF) resulting in hypercoagulation. Adequate therapy in controlling inflammation due to COVID 19 has shown clinical improvement in stroke infarct patients. Conclusion: There are 2 cases of stroke infarction in patients with covid 19 who have comorbidities. The first case with COVID advanced stages experienced a worsening of the condition despite being given appropriate therapy. The second case with COVID middle stages experienced an improvement in the condition after the viral inflammatory factors were controlled and the comorbidity was well controlled.

Encapsulation of Cadmium-Free InP/ZnSe/ZnS Quantum Dots in Poly(LMA-co-EGDMA) Microparticles via Co-flow Droplet Microfluidics.

Quantum dots (QDs) are semiconductor nanocrystals that are used in optoelectronic applications. Most modern QDs are based on toxic metals, for example Cd, and do not comply with the European Restriction of Hazardous Substances regulation of the European Union. Latest promising developments focus on safer QD alternatives based on elements from the III-V group. However, the InP-based QDs lack an overall photostability under environmental influences. One design path of achieving stability is through encapsulation in cross-linked polymer matrices with the possibility to covalently link the matrix to surface ligands of modified core-shell QDs. The work focuses on the formation of polymer microbeads suitable for InP-based QD encapsulation, allowing for an individual protection of QDs and an improved processibility via this particle-based approach. For this, a microfluidic based method in the co-flow regime is used that consists of an oil-in-water droplet system in a glass capillary environment. The generated monomer droplets are polymerized in-flow into poly(LMA-co-EGDMA) microparticles with embedded InP/ZnSe/ZnS QDs using a UV initiation. They demonstrate how a successful polymer microparticle formation via droplet microfluidics produces optimized matrix structures leading to a distinct photostability improvement of InP-based QDs compared to nonprotected QDs.

Interaction-Limited Aggregation: Fine-Tuning the Size of pNIPAM Particles by Association with Hydrophobic Ions.

We have investigated the formation of stable clusters of poly(N-isopropylacrylamide) (pNIPAM) chains in water at temperatures above the lower critical solution temperature (LCST), induced by the presence of sodium tetraphenylborate, NaPh4B. The hydrophobic Ph4B- ions interact strongly with the pNIPAM chains, providing them with a net effective negative charge, which leads to the stabilization of pNIPAM clusters for temperatures above the LCST, with a mean cluster size that depends non-monotonically on salt concentration. Combining experiments with physical modeling at the mesoscopic level and atomistic molecular dynamic simulations, we show that this effect is caused by the interplay between the hydrophobic attraction between pNIPAM chains and the electrostatic repulsion induced by the associated Ph4B- ions. These results provide insight on the significance of weak associative anion-polymer interaction driven by hydrophobic interaction and how this anionic binding can prevent macroscopic phase separation. Harvesting the competition between attractive hydrophobic and repulsive electrostatic interaction opens avenues for the dynamic control of the formation of well-calibrated polymer microparticles.