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The isolation of small extracellular vesicles (sEVs), including those secreted by pathological cells, with high efficiency and purity is highly demanded for research studies and practical applications. Conventional sEV isolation methods suffer from low yield, presence of contaminants, long-term operation and high costs. Bead-assisted platforms are considered to be effective for trapping sEVs with high recovery yield and sufficient purity for further molecular profiling. In this study, magnetically responsive beads made of calcium carbonate (CaCO3) particles impregnated with iron oxide (Fe3O4) nanoparticles are fabricated using a freezing-induced loading (FIL) method. The developed magnetic beads demonstrate sufficient magnetization and can be collected by a permanent magnet, ensuring their rapid and gentle capture from an aqueous solution. The tannic acid on the surface of magnetic beads is formed by a layer-by-layer (LbL) method and is used to induce coupling of sEVs with the surface of magnetic beads. These tannic acid coated magnetic beads (TAMB) were applied to capture sEVs derived from MCF7 and HCT116 cell lines. Quantitative data derived from nanoparticle tracking analysis (NTA) and BCA methods revealed the capture efficiency and recovery yield of about 60%. High-resolution transmission electron microscopy (HRTEM) imaging of sEVs on the surface of TAMBs indicated their structural integrity. Compared with the size exclusion chromatography (SEC) method, the proposed approach demonstrated comparable efficiency in terms of recovery yield and purity, while offering a relatively short operation time. These results highlight the high potential of the TAMB approach for the enrichment of sEVs from biological fluids, such as cell culture media. [ABSTRACT FROM AUTHOR]

The development of a sensitive and reliable method for the isolation and detection of pathologically relevant small extracellular vesicles (sEVs) remains a challenge. Herein we present a method for characterization of sEVs that is based on the isolation of sEVs by anti‐CD63 aptamer conjugated magnetic beads and detecting the presence of the membrane proteins on their surface using anti‐EpCAM and anti‐HER2 designed ankyrin repeat proteins (DARPins). We perform a comparative study for identification of EpCAM and HER2 surface proteins in sEVs derived from MCF7, SKOV3, MDA‐MB‐231 and CHO cell lines and blood plasma of a healthy donor. Both DRAPins show high specificity to EpCAM and HER2 receptors with a limit of detection about 104 vesicles for MCF7 and Plasma sEVs and 105 vesicles for SKOV3 sEVs. Combination of magnetic capture with highly reactive DARPin probes made it possibly to reduce total assay time to 1 h. This method provides a basis for isolating and quantifying various sEV subpopulations that contain disease specific surface‐markers. [ABSTRACT FROM AUTHOR]

The present study focuses on the immobilization of the bacterial ribonuclease barnase (Bn) into submicron porous calcium carbonate (CaCO3) particles. For encapsulation, we apply adsorption, freezing-induced loading and co-precipitation methods and study the effects of adsorption time, enzyme concentration and anionic polyelectrolytes on the encapsulation efficiency of Bn. We show that the use of negatively charged dextran sulfate (DS) and ribonucleic acid from yeast (RNA) increases the loading capacity (LC) of the enzyme on CaCO3 particles by about 3-fold as compared to the particles with Bn itself. The ribonuclease (RNase) activity of encapsulated enzyme depends on the LC of the particles and transformation of metastable vaterite to stable calcite, as studied by the assessment of enzyme activities in particles. [ABSTRACT FROM AUTHOR]

Release from polyelectrolyte multilayer microcapsules represents one of the most important steps enabling practical use of the microcapsules. A number of biological and non-biological applications are envisaged by proper encapsulation of molecules of interest and their release performance. Since the invention of the microcapsules at the Max-Planck Institute of Colloids and Interfaces in 1998 the work towards microcapsule assisted release has undergone tremendous progress. Almost simultaneously with development of release approaches an extensive base of applications has been advanced. In this progress report the release from the capsules in a solution and those immobilized on the surface of polymeric films is addressed. [ABSTRACT FROM AUTHOR]

The process of porous calcium carbonate (CaCO3) covering on electrospun poly(ε-caprolactone) (PCL) fibers is described in this study. Uniform CaCO3 coatings, composed of vaterite microparticles and its aggregates, were formed on PCL fibers by mineral precipitation from solution under ultrasonic treatment. The porous structure of CaCO3 in vaterite polymorphic form is useful for loading of various substances (drugs and nanoparticles), and this property makes vaterite an appropriate material for design of drug delivery systems. Such mineralization was implemented to attain therapeutic and/or biological activity of tissue engineering scaffolds based on electrospun PCL, by means of CaCO3 coatings. Various structures and polymorphs of CaCO3 coatings were obtained by variation of growth conditions (time of fiber incubation in work solution, ultrasonic treatment of this system). Coating homogeneity, CaCO3 polymorphic form, morphology, and CaCO3 mass can be controlled by number of successive stages of fibrous material treatment. Cytotoxicity tests showed that PCL fibers mineralized with CaCO3 did not release substances toxic for cells. SEM images of PCL/CaCO3 scaffolds cultured with cells demonstrate that scaffolds supported cell adhesion and spreading. The presented results show the new technique of controlled PCL scaffold mineralization with vaterite, and an opportunity of using PCL/CaCO3 as scaffolds for tissue engineering. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 94-103, 2017. [ABSTRACT FROM AUTHOR]

The present study focuses on theformation of microcapsules containingcatalytically active l-asparaginase (L-ASNase), a proteindrug of high value in antileukemic therapy. We make use of the layer-by-layer(LbL) technique to coat protein-loaded calcium carbonate (CaCO3) particles with two or three poly dextran/poly-l-arginine-based bilayers. To achieve high loading efficiency, theCaCO3template was generated by coprecipitation with theenzyme. After assembly of the polymer shell, the CaCO3corematerial was dissolved under mild conditions by dialysis against 20mM EDTA. Biochemical stability of the encapsulated l-asparaginasewas analyzed by treating the capsules with the proteases trypsin andthrombin, which are known to degrade and inactivate the enzyme duringleukemia treatment, allowing us to test for resistance against proteolysisby physiologically relevant proteases through measurement of residual l-asparaginase activities. In addition, the thermal stability,the stability at the physiological temperature, and the long-termstorage stability of the encapsulated enzyme were investigated. Weshow that encapsulation of l-asparaginase remarkably improvesboth proteolytic resistance and thermal inactivation at 37 °C,which could considerably prolong the enzyme’s in vivo half-lifeduring application in acute lymphoblastic leukemia (ALL). Importantly,the use of low EDTA concentrations for the dissolution of CaCO3by dialysis could be a general approach in cases where theactivity of sensitive biomacromolecules is inhibited, or even irreversiblydamaged, when standard protocols for fabrication of such LbL microcapsulesare used. Encapsulated and free enzyme showed similar efficacies indriving leukemic cells to apoptosis. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman spectroscopy (SERS) is a powerful technique for biosensing. However, SERS analysis has several concerns: the signal is limited by a number of molecules and the area of the plasmonic substrate in the laser hotspot, and quantitative analysis in a low-volume droplet is confusing due to the change of concentration during quick drying. The usage of hollow-core microstructured optical fibers (HC-MOFs) is thought to be an effective way to improve SERS sensitivity and limit of detection through the effective irradiation of a small sample volume filling the fiber capillaries. In this paper, we used layer-by-layer assembly as a simple method for the functionalization of fiber capillaries by gold nanoparticles (seeds) with a mean diameter of 8 nm followed by UV-induced chloroauric acid reduction. We also demonstrated a simple and quick technique used for the analysis of the SERS platform formation at every stage through the detection of spectral shifts in the optical transmission of HC-MOFs. The enhancement of the Raman signal of a model analyte Rhodamine 6G was obtained using such type of SERS platform. Thus, a combination of nanostructured gold coating as a SERS-active surface and a hollow-core fiber as a microfluidic channel and a waveguide is perspective for point-of-care medical diagnosis based on liquid biopsy and exhaled air analysis. [ABSTRACT FROM AUTHOR]

We present a novel strategy to fabricate anisotropic multicompartment Janus capsules by embedding larger containers into a soft poly-l-lysine/hyaluronic acid (PLL/HA) polymeric film, followed by adsorption of smaller containers on top of their unmasked surface. This research is also attractive for developing substrates for cell cultures. [ABSTRACT FROM AUTHOR]

The present study focuses on the immobilization of the bacterial ribonuclease barnase (Bn) into submicron porous calcium carbonate (CaCO 3 ) particles. For encapsulation, we apply adsorption, freezing-induced loading and co-precipitation methods and study the effects of adsorption time, enzyme concentration and anionic polyelectrolytes on the encapsulation efficiency of Bn. We show that the use of negatively charged dextran sulfate (DS) and ribonucleic acid from yeast (RNA) increases the loading capacity (LC) of the enzyme on CaCO 3 particles by about 3-fold as compared to the particles with Bn itself. The ribonuclease (RNase) activity of encapsulated enzyme depends on the LC of the particles and transformation of metastable vaterite to stable calcite, as studied by the assessment of enzyme activities in particles.