Characterization Of Microparticles Research Articles

Original research paper. Characterization and taste masking evaluation of microparticles with cetirizine dihydrochloride and methacrylate-based copolymer obtained by spray drying.

Taste of a pharmaceutical formulation is an important parameter for the effectiveness of pharmacotherapy. Cetirizine dihydrochloride (CET) is a second-generation antihistamine that is commonly administered in allergy treatment. CET is characterized by extremely bitter taste and it is a great challenge to successfully mask its taste; therefore the goal of this work was to formulate and characterize the microparticles obtained by the spray drying method with CET and poly(butyl methacrylate-co-(2-dimethylaminoethyl) methacrylate-co-methyl methacrylate 1:2:1 copolymer (Eudragit E PO) as a barrier coating. Assessment of taste masking by the electronic tongue has revealed that designed formulations created an effective taste masking barrier. Taste masking effect was also confirmed by the in vivo model and the in vitro release profile of CET. Obtained data have shown that microparticles with a drug/polymer ratio (0.5:1) are promising CET carriers with efficient taste masking potential and might be further used in designing orodispersible dosage forms with CET.

Emerging technologies in solid drug delivery: an interview with Nadia Passerini.

Nadia Passerini is interviewed by Hannah Makin, Commission Editor. Nadia Passerini is Associate Professor of Pharmaceutical Technology at the University of Bologna (Bologna, Italy). She obtained the degree in Pharmaceutical Chemistry and Technology at the University of Bologna in 1992 and the PhD in Pharmaceutical Science in 1997. Her research focuses on the study of drug delivery systems, developing new technologies and new apparatus for the production of solid dosage forms (microparticles, granules and tablets), which can optimize the bioavailability of drugs according to the specific needs of the therapy. Furthermore, she is interested in the solid-state characterization of the produced delivery systems in order to correlate their physicochemical properties to the in vitro release of the drugs. Currently, her research focuses in particular on the production and characterization of microparticles produced by the spray congealing technology. She is author of over 50 international peer-reviewed publications and over 50 contributions (poster and oral presentations) to national and international conferences.

Microparticle Formation in Peritoneal Dialysis: A Proof of Concept Study.

Background:Injury to the mesothelial layer of the peritoneal membrane during peritoneal dialysis (PD) is implicated in loss of ultrafiltration capacity, but there are no validated biomarkers for mesothelial cell injury. Microparticles (MPs) are 0.1 to 1.0 µm membrane vesicles shed from the cell surface following injury and are sensitive markers of tissue damage. Formation of MPs in the peritoneal cavity during PD has not been reported to date.Methods:We designed a single-center, proof of concept study to assess whether peritoneal solution exposure induces formation of mesothelial MPs suggestive of PD membrane injury. We examined MP levels in PD effluents by electron microscopy, nanoparticle tracking analysis (NTA), flow cytometry, procoagulant activity, and Western blot.Results:NTA identified particles in the size range of 30 to 900 nm, with a mean of 240 (SE: 10 nm). MP levels increased in a progressive manner during a 4-hour PD dwell. Electron microscopy confirmed size and morphology of vesicles consistent with characteristics of MPs as well as the presence of mesothelin on the surface. Western blot analysis of the MP fraction also identified the presence of mesothelin after 4 hours, suggesting that MPs found in PD effluents may arise from mesothelial cells.Conclusions:Our results suggest that MPs are formed and accumulate in the peritoneal cavity during PD, possibly as a stress response. Assessing levels of MPs in PD effluents may be useful as a biomarker for peritoneal membrane damage.

福島第一原子力発電所事故により1号機から放出された放射性粒子の放射光マイクロビームX線分析を用いる化学性状の解明

福島第一原子力発電所事故により1号機から放出された放射性粒子の放射光マイクロビームX線分析を用いる化学性状の解明

Isolation and Characterization of Circulating Microparticles by Flow Cytometry.

Microparticles are small fragments (0.1-1.0 μm) of cellular membrane which are shed by cells under conditions of stress. As levels of circulating microparticles are elevated in disease, there has been significant interest in their assessment and quantification under pathological conditions. Here we describe a protocol for the isolation of microparticles from plasma samples and their characterization/quantification by flow cytometry. This assay has been employed for the assessment of microparticle levels in both human and animal plasma and may also be modified for the characterization of microparticles from culture media or from other biological samples (i.e., urine).

근적외선 유도 약물방출을 위한 키토산 미세입자의 제조와 평가

근적외선 유도 약물방출을 위한 키토산 미세입자의 제조와 평가

Preparation and physicochemical characterization of spray-dried and jet-milled microparticles containing bosentan hydrate for dry powder inhalation aerosols.

The objectives of this study were to prepare bosentan hydrate (BST) microparticles as dry powder inhalations (DPIs) via spray drying and jet milling under various parameters, to comprehensively characterize the physicochemical properties of the BST hydrate microparticles, and to evaluate the aerosol dispersion performance and dissolution behavior as DPIs. The BST microparticles were successfully prepared for DPIs by spray drying from feeding solution concentrations of 1%, 3%, and 5% (w/v) and by jet milling at grinding pressures of 2, 3, and 4 MPa. The physicochemical properties of the spray-dried (SD) and jet-milled (JM) microparticles were determined via scanning electron microscopy, atomic force microscopy, dynamic light scattering particle size analysis, Karl Fischer titration, surface analysis, pycnometry, differential scanning calorimetry, powder X-ray diffraction, and Fourier transform infrared spectroscopy. The in vitro aerosol dispersion performance and drug dissolution behavior were evaluated using an Anderson cascade impactor and a Franz diffusion cell, respectively. The JM microparticles exhibited an irregular corrugated surface and a crystalline solid state, while the SD microparticles were spherical with a smooth surface and an amorphous solid state. Thus, the in vitro aerosol dispersion performance and dissolution behavior as DPIs were considerably different due to the differences in the physicochemical properties of the SD and JM microparticles. In particular, the highest grinding pressures under jet milling exhibited excellent aerosol dispersion performance with statistically higher values of 56.8%±2.0% of respirable fraction and 33.8%±2.3% of fine particle fraction and lower mass median aerodynamic diameter of 5.0±0.3 μm than the others (P<0.05, analysis of variance/Tukey). The drug dissolution mechanism was also affected by the physicochemical properties that determine the dissolution kinetics of the SD and JM microparticles, which were well fitted into the Higuchi and zero-order models, respectively.

Light-scattering gating and characterization of plasma microparticles.

Flow cytometry method (FCM) is widely used for analysis of cell-derived microparticles (MPs). Numerous efforts are currently aimed to standardize these measurements among different instruments. We push the FCM characterization of MPs to the limit based on rigorous simulation of measured signals. We measured forward- and side-scatter (FSC/SSC) signals and angle-resolved light-scattering profiles (LSPs) of polystyrene microspheres and MPs, including their aggregates, using a scanning flow cytometer (SFC). We used the Mie theory to (1) accurately evaluate instrument detection limits; (2) construct FSC/SSC gates for MPs in absolute scales of size and refractive index (RI); and (3) determine size and RI of individual spherical MPs. LSPs were used for advanced characterization, including differentiation of spherical and nonspherical particles. The proposed absolute FSC/SSC gating is naturally standardized for any FCM instrument, given the knowledge of its optical system and leads to instrument-independent analysis of MPs. The inverse Mie problem has a unique solution only for some regions of size and RI and uncertainties rapidly increase with decreasing size and RI. The developed methods are applicable to any flow cytometer, but are limited by assumption of particle sphericity. The latter can be relaxed only if additional signals, such as LSP, are measured.

Microencapsulated SLN: An innovative strategy for pulmonary protein delivery

Associating protein with nanoparticles is an interesting strategy to improve their bioavailability and biological activity. Solid lipid nanoparticles (SLN) have been sought as carriers for therapeutic proteins transport to the lung epithelium. Nevertheless, because of their low inertia, nanoparticles intended for pulmonary application usually escape from lung deposition. To overcome this problem, the production of spray-dried powders containing nanoparticles has been recently reported. Herein we developed new hybrid microencapsulated SLN for pulmonary administration, containing a model protein (papain, PAP). PAP was adsorbed onto glyceryl dibehenate and glyceryl tristearate SLN. Physical characterization using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) confirmed the interaction between PAP and SLN corroborating that the protein was efficiently adsorbed at SLN’s surface. PAP adsorption onto SLN (PAP-SLN) slightly increased particle size, while decreasing the SLN negative surface charge. The adsorption process followed a Freundlich type of adsorption isotherm. Nanoformulations were then spray-dried, originating spherical microparticles with suitable aerodynamic characteristics. Full characterization of microparticles was performed using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and isothermal titration calorimetry (ITC). PAP was released from dry powders in a higher extent when compared with non spray-dried SLN. Nevertheless, protein stability was kept throughout microsphere production, as assessed by SDS-PAGE.

464 - Characterization of Microparticles and Exosomes from Red Blood Cells During Storage: Implications for Transfusion Toxicity

Red blood cell (RBC) storage for up to 42 days is a mainstay therapeutic in transfusion medicine. During storage several biochemical changes and metabolic alterations occur in RBCs that associate with increased morbidity and mortality in transfusion recipients. These changes include formation of smaller microvesicles comprising microparticles (MPs) and exosomes (Exo). Importantly, depending on the size and composition, these vesicles may elicit circulatory dysfunction and inflammation. In addition, our recent data has identified free heme and cell free hemoglobin as independent mediators of pro-inflammatory and oxidant activity associated with stored RBC transfusions. In this study we determined the relative formation of MPs and Exo from leukoreduced RBCs stored for 7-10d or 35-52d and assessed their composition with hemoglobin, heme and antioxidants (glutathione and Peroxiredoxin-2, catalase, superoxide dismutase, and Thioredoxin). Both MPs and Exo increased with storage, with the former being ∼10-fold higher in total number than the latter. The total glutathione content normalized to oxyHb (pro-oxidant) was significantly decreased by 2.5 and 6 fold respectively in MPs and Exo compared to intact RBC. Interestingly, high molecular weight antioxidant proteins, Peroxiredoixin-2, Cu/Zn SOD and Thioredoxin were detected in both MPs and Exo, but present as higher MWt complexes (under reducing condition) indicative of oxidatively-cross linked proteins. Moreover, these complexes were more abundant in Exo compared to MPs normalized to both protein and OxyHb. Furthermore, addition of H 2 O 2 failed to alter Prx-2 complex MWt indicating that the Prx-2 system is unable to metabolize and protect MPs or Exo against H 2 O 2 induced stress. These data suggest that MP’s and Exo harbor more oxidatively modified proteins and mediators, and contain lower antioxidants. We speculate that transfusion with these microvesicles will lead to pro-oxidant stress and contribute to inflammatory stress associated with transfused with older stored RBCs.

Characterization of microparticles in patients with venous malformations of the head and neck.

To determine the basic biochemical features of microparticles (MP) in patients with venous malformation (VM) of the head and neck. Microparticles were isolated from peripheral venous blood of VM patients or healthy subjects and from lesional fluid of VM patients. Flow cytometry and real-time polymerase chain reaction were employed to determine the concentration, cellular origin, and RNA expression of obtained MP. A functional coagulation test was applied to measure the coagulant activity of MP. Circulating levels of total MP, platelet-derived MP, and endothelial MP were significantly elevated in VM patients and were consistently increased in VM patients with more extensive lesions. Lesional MP (MP from lesional fluid of VM) in VM patients were more abundant than circulating MP from VM patients or healthy subjects. Moreover, MP from VM patients displayed markedly distinct mRNA and microRNA expression compared with healthy subjects. Furthermore, MP from VM patients exhibited enhanced procoagulant activity, as evidenced by significantly shorter coagulation time. This study demonstrates for the first time that patients with VM have an altered MP profile and MP may be associated with VM-associated thrombogenesis. Further studies are required to explore the precise pathophysiological roles of MP in VM.

Novel Spray Dried Glycerol 2-Phosphate Cross-Linked Chitosan Microparticulate Vaginal Delivery System-Development, Characterization and Cytotoxicity Studies.

Chitosan microparticulate delivery systems containing clotrimazole were prepared by a spray drying technique using glycerol 2-phosphate as an ion cross-linker. The impact of a cross-linking ratio on microparticle characteristics was evaluated. Drug-free and drug-loaded unmodified or ion cross-linked chitosan microparticles were examined for the in vitro cytotoxicity in VK2/E6E7 human vaginal epithelial cells. The presence of glycerol 2-phosphate influenced drug loading and encapsulation efficacy in chitosan microparticles. By increasing the cross-linking ratio, the microparticles with lower diameter, moisture content and smoother surface were observed. Mucoadhesive studies displayed that all formulations possessed mucoadhesive properties. The in vitro release profile of clotrimazole was found to alter considerably by changing the glycerol 2-phosphate/chitosan ratio. Results from cytotoxicity studies showed occurrence of apoptotic cells in the presence of chitosan and ion cross-linked chitosan microparticles, followed by a loss of membrane potential suggesting that cell death might go through the mitochondrial apoptotic pathway.

Efficient polymeric material for separation of human hemoglobin

In this study, negatively charged acrylic acid was used as a functional ligand to synthesise net-poly(2-hydroxyethyl methacrylate-co-acrylic acid) microparticles for the removal of hemoglobin having a positively charged Fe2+ ion in the core, as an alternative to conventional techniques to achieve a cost effective high-capacity purification. The characterization of microparticles was performed via Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, the Brunauer – Emmett – Teller surface area analysis, and swelling test methods. Optimum adsorption conditions such as pH, initial hemoglobin concentration, temperature, and interaction time were studied batch wise. The highest adsorption capacity of microparticles was observed at pH 7.4 as 1276.4 mg hemoglobin/g polymer. The reusability of microparticles was also promising with ∼5% decrease in the adsorption capacity at the end of the five adsorption-desorption cycles.

Formulation and Characterization of Polysaccharide Microparticles for Pulmonary Delivery of Sodium Cromoglycate.

Sodium cromoglycate (SC) is an antiasthmatic and antiallergenic drug commonly used for chronic inhalation therapy; however, many daily intakes are required due to the fast drug clearance from airways. For these reasons, SC polymeric particles for inhalatory administration with adequate aerosolization and mucoadhesive properties were designed to prolong the drug residence time in the site of action. Sodium carboxymethylcellulose (CMCNa), sodium hyaluronate, and sodium alginate were selected to co-process SC by spray drying. The influence of these polysaccharides on the spray drying process and powder quality was evaluated (among others, morphology, size, moisture content, hygroscopicity, flowability, densities, liquid sorption, and stability). In vitro aerosolization, drug release, and mucoadhesion performance were also studied. Particularly, a novel method to comparatively evaluate the interaction between formulations and mucin solution (mucoadhesion test) was proposed as a rapid methodology to measure adhesion properties of inhalable particles, being the results as indicative of clearance probability. Among all the studied formulations, the powder based on SC and CMCNa exhibited the best mucoadhesion and aerosolization performance, the highest process yield and adequate moisture content, hygroscopicity, and stability. SC-CMCNa formulation arose as a promising inhalatory system to reduce the daily intakes and to increase the patient compliance.

Preparation and characterization of chitosan microparticles for immunoaffinity extraction and determination of enrofloxacin

The use of chitosan microparticles as chromatographic support has received much attention. In this study, the effects of process parameters, namely, chitosan molecular weight, chitosan concentration, molar ratio of amino group to aldehyde group, volume ratio of water to oil phase and stirring speed on the size and size distribution of chitosan microparticles and their application for immunoaffinity extraction were extensively investigated. Size distribution analysis indicated that the average diameter of the microparticles was 124μm with Span value of 1.1. The obtained microparticles exhibited low non-specific adsorption and kept stable in the pH range 4.0–10.0. Immunoaffinity chromatography (IAC) column was prepared by coupling antibody against enrofloxacin (ENR) with chitosan microparticles. Further characterization indicated that the binding capacity of the column was 4392ng ENR/mL gel and the variation of ENR extraction efficiency among columns was less than 5.2%. When challenged with ENR-fortified bovine milk samples, recoveries of ENR by immunoaffinity extraction were found to be in the range of 85.9% to 101.9%, demonstrated the feasibility of the prepared IAC columns for sample clean-up in ENR residue determination.

Development and characterization of polymeric microparticles containing praziquantel for pediatric treatment of schistosomiasis

Development and characterization of polymeric microparticles containing praziquantel for pediatric treatment of schistosomiasis

Development of a NanoBioAnalytical platform for "on-chip" qualification and quantification of platelet-derived microparticles

Blood microparticles (MPs) are small membrane vesicles (50–1000nm), derived from different cell types. They are known to play important roles in various biological processes and also recognized as potential biomarkers of various health disorders. Different methods are currently used for the detection and characterization of MPs, but none of these methods is capable to quantify and qualify total MPs at the same time, hence, there is a need to develop a new approach for simultaneous detection, characterization and quantification of microparticles. Here we show the potential of surface plasmon resonance (SPR) method coupled to atomic force microscopy (AFM) to quantify and qualify platelet-derived microparticles (PMPs), on the whole nano-to micro-meter scale. The different subpopulations of microparticles could be determined via their capture onto the surface using specific ligands. In order to verify the correlation between the capture level and the microparticles concentration in solution, two calibration standards were used: Virus-Like Particles (VLPs) and synthetic beads with a mean diameter of 53nm and 920nm respectively. The AFM analysis of the biochip surface allowed metrological analysis of captured PMPs and revealed that more than 95% of PMPs were smaller than 300nm. Our results suggest that our NanoBioAnalytical platform, combining SPR and AFM, is a suitable method for a sensitive, reproducible, label-free characterization and quantification of MPs over a wide concentration range (≈107 to 1012 particles/mL; with a limit of detection (LOD) in the lowest ng/µL range) which matches with their typical concentrations in blood.

Structural and functional characterization of endothelial microparticles released by cigarette smoke.

Circulating endothelial microparticles (EMPs) are emerging as biomarkers of chronic obstructive pulmonary disease (COPD) in individuals exposed to cigarette smoke (CS), but their mechanism of release and function remain unknown. We assessed biochemical and functional characteristics of EMPs and circulating microparticles (cMPs) released by CS. CS exposure was sufficient to increase microparticle levels in plasma of humans and mice, and in supernatants of primary human lung microvascular endothelial cells. CS-released EMPs contained predominantly exosomes that were significantly enriched in let-7d, miR-191; miR-126; and miR125a, microRNAs that reciprocally decreased intracellular in CS-exposed endothelium. CS-released EMPs and cMPs were ceramide-rich and required the ceramide-synthesis enzyme acid sphingomyelinase (aSMase) for their release, an enzyme which was found to exhibit significantly higher activity in plasma of COPD patients or of CS-exposed mice. The ex vivo or in vivo engulfment of EMPs or cMPs by peripheral blood monocytes-derived macrophages was associated with significant inhibition of efferocytosis. Our results indicate that CS, via aSMase, releases circulating EMPs with distinct microRNA cargo and that EMPs affect the clearance of apoptotic cells by specialized macrophages. These targetable effects may be important in the pathogenesis of diseases linked to endothelial injury and inflammation in smokers.

Nucleotide incorporated magnetic microparticles for isolation of DNA

For the comprehensive understanding of many diseases, especially genetic disease, the highly purified deoxyribonucleic acid (DNA) is needed to perform in-detail studies. There are various methods to obtain highly purified DNA, but low in number. In this study, Fe&Ni-mc-poly (2-hydroxyethyl methacrylate-adenine methacrylate) [poly(HEMA-AdeM)] microparticles were synthesized to get high purification ratio because of natural and thus selective interaction between adenine on the microparticles and thymine on the DNA molecule and also high amount of DNA purified. For the characterization of microparticles scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), elemental analysis, swelling ratio and zeta size analysis methods were performed. All experiments were performed batch-wise for the determination of optimum conditions such as pH, initial DNA concentration, temperature and interaction time. At the end of the all study, the desorption yield was obtained as 97.7% and after 5 adsorption-desorption cycle, the adsorption capacity was decreased only 3%.

Copper-coordinating polymers for marine anti-fouling coatings: A physicochemical and electrochemical study of ternary system of copper, PMMA and poly(TBTA)

Biofouling is a general problem in marine applications. Copper has been used as an anti-biofouling agent in marine coatings for decades; however, its widespread use has resulted in regulatory restrictions due to high copper concentrations in harbors and areas with limited water circulation. Here we present a new approach for anti-fouling coatings using microparticles of poly(tris[(benzyltriazol)methyl]amine) (poly(TBTA)) polymers to absorb and control the interaction between a surface coating and the copper naturally present in seawater with the intention of creating a flux of copper across the water/coating interface. The preparation and characterization of microparticles of poly(TBTA) as well as hybrid PMMA: poly(TBTA) has been described to study the feasibility of tuning the copper-coordination properties of a generic marine coating using these paint-compatible microparticles. The properties of microparticles of poly(TBTA), PMMA and the PMMA: poly(TBTA) hybrid were therefore studied using cyclic voltammetry and NMR spectroscopy. It is demonstrated that the copper ions interact specifically with microparticles containing the coordinating polymer poly(TBTA) and that these microparticles have a high absorption capacity of more than 5 wt% for copper.