Amino Surface Modification and Fluorescent Labelling of Porous Hollow Organosilica Particles: Optimization and Characterization

Surface modification of silica nanoparticles with organic functional groups while maintaining colloidal stability remains a synthetic challenge. This work aimed to prepare highly dispersed porous hollow organosilica particles (pHOPs) with amino surface modification. The amino-surface modification of pHOPs was carried out with 3-aminopropyl(diethoxy)methylsilane (APDEMS) under various reaction parameters, and the optimal pHOP-NH2 sample was selected and labelled with fluorescein isothiocyanate (FITC) to achieve fluorescent pHOPs (F-HOPs). The prepared pHOPs were thoroughly characterized by transmission electron microscopy, dynamic light scattering, FT-IR, UV-Vis and fluorescence spectroscopies, and microfluidic resistive pulse sensing. The optimal amino surface modification of pHOPs with APDEMS was at pH 10.2, at 60 °C temperature with 10 min reaction time. The positive Zeta potential of pHOP-NH2 in an acidic environment and the appearance of vibrations characteristic to the surface amino groups on the FT-IR spectra prove the successful surface modification. A red-shift in the absorbance spectrum and the appearance of bands characteristic to secondary amines in the FTIR spectrum of F-HOP confirmed the covalent attachment of FITC to pHOP-NH2. This study provides a step-by-step synthetic optimization and characterization of fluorescently labelled organosilica particles to enhance their optical properties and extend their applications

Antimicrobial, Antioxidant and Antiproliferative Secondary Metabolites from Inonotus nidus-pici

Inonotus nidus-pici is a sterile conk which produces macrofungus, a neglected Central-Eastern European relative of the prized Inonotus obliquus, also known as chaga. Investigation of the methanol extract of the poroid fungus I. nidus-pici resulted in the isolation of citropremide (1), 3,4-dihydroxybenzalacetone (2) , lanosterol (3), ergost-6,8,22-trien-3β-ol (4), and ergosterol peroxide (5). The structures of fungal compounds were determined on the basis of one- and two-dimensional NMR and MS spectroscopic analysis. Compounds 1–2 and 4–5 were evaluated for their antioxidant and antimicrobial properties against several bacterial and fungal strains. 3,4-dihydroxybenzalacetone (2) and ergost-6,8,22-trien-3β-ol (4) demonstrated moderate antimicrobial activity, while the former possessed notable antioxidant activity in DPPH assay. The antiproliferative examinations performed on three human cancer (MES-SA, MES-SA/Dx5, A431) cell lines demonstrated that compounds 4 and 5 have notable cytotoxic activity with IC values in micromolar range. The current study represents the first report on the chemical profile of I. nidus-pici, providing a comprehensive study on the isolation and structure determination of bioactive secondary metabolites of this macrofungus

Synthesis of Porous Hollow Organosilica Particles with Tunable Shell Thickness

Porous hollow silica particles possess promising applications in many fields, ranging from drug delivery to catalysis. From the synthesis perspective, the most challenging parameters are the monodispersity of the size distribution and the thickness and porosity of the shell of the particles. This paper demonstrates a facile two-pot approach to prepare monodisperse porous-hollow silica particles with uniform spherical shape and well-tuned shell thickness. In this method, a series of porous-hollow inorganic and organic-inorganic core-shell silica particles were synthesized via hydrolysis and condensation of 1,2-bis(triethoxysilyl) ethane (BTEE) and tetraethyl orthosilicate (TEOS) in the presence of hexadecyltrimethylammonium bromide (CTAB) as a structure-directing agent on solid silica spheres as core templates. Finally, the core templates were removed via hydrothermal treatment under alkaline conditions. Transmission electron microscopy (TEM) was used to characterize the particles′ morphology and size distribution, while the changes in the chemical composition during synthesis were followed by Fourier-transform infrared spectroscopy. Single-particle inductively coupled plasma mass spectrometry (spICP-MS) was applied to assess the monodispersity of the hollow particles prepared with different reaction parameters. We found that the presence of BTEE is key to obtaining a well-defined shell structure, and the increase in the concentration of the precursor and the surfactant increases the thickness of the shell. TEM and spICP-MS measurements revealed that fused particles are also formed under suboptimal reaction parameters, causing the broadening of the size distribution, which can be preceded by using appropriate concentrations of BTEE, CTAB, and ammonia

Myeloid but not plasmacytoid blood DCs possess Th1 polarizing and Th1/Th17 recruiting capacity in psoriasis

K

Lipid nanoparticles with erythrocyte cell-membrane proteins

When the separated erythrocyte membranes (known as ghosts) are ultrasonicated, a significant part of the membrane proteins are released in the aqueous solvent, instead of being incorporated into the membranes of the formed nanoerythrosomes. In contrast to their membrane-bound counterparts, where helices and β-strands dominate, the released proteins show perturbed secondary structures with an increased ratio of helices, presumably participating in molten globules, as it has been revealed by circular dichroism (CD) and infra-red spectroscopy (IR). The shape and size of these proteins is diverse, and even their aggregates appear. When excess lipid (palmitoyl-lysophosphatidylcholine, LPC) is added to different ghost-derivatives (the full nanoerythrosome system, and its ultracentrifugation pellet and supernatant) in 2 × and 5 × lipid-to-protein mass ratio, various lipid nanoparticles are produced. The core–shell and nanodisc structural models obtained by small-angle X-ray scattering (SAXS) indicate that the choice of the precursor system has a more prominent effect on the resulting shape than the amount of lipid added: when starting from the protein-rich supernatant fraction, small (approx. 5 nm high and 7 nm wide) nanodisks are created. When lipid membranes are already present (in the pellet and the full nanoerythrosome fraction), similar LPC addition results in prolate ellipsoidal particles, with an aspect ratio between 3 and 5, and decreasing overall size when the amount of added lipid is increased. The ellipsoids formed from the total nanoerythrosome fraction are smaller than those from the ultracentrifugation pellet (longest axis around 15 vs 26 nm), whereas for higher LPC-to-protein ratio, the size in both cases reduce to nearly the same (13–14 nm) in both cases

Storage conditions determine the characteristics of red blood cell derived extracellular vesicles

Extracellular vesicles (EVs) are released during the storage of red blood cell (RBC) concentrates and might play adverse or beneficial roles throughout the utilization of blood products (transfusion). Knowledge of EV release associated factors and mechanism amends blood product management. In the present work the impact of storage time and medium (blood preserving additive vs isotonic phosphate buffer) on the composition, size, and concentration of EVs was studied using attenuated total reflection infrared (ATR-IR) spectroscopy, microfluidic resistive pulse sensing (MRPS) and freeze-fraction combined transmission electron micrography (FF-TEM). The spectroscopic protein-to-lipid ratio based on amide and the C–H stretching band intensity ratio indicated the formation of various vesicle subpopulations depending on storage conditions. After short storage, nanoparticles with high relative protein content were detected. Spectral analysis also suggested differences in lipid and protein composition, too. The fingerprint region (from 1300 to 1000 cm−1) of the IR spectra furnishes additional information about the biomolecular composition of RBC-derived EVs (REVs) such as adenosine triphosphate (ATP), lactose, glucose, and oxidized hemoglobin. The difference between the vesicle subpopulations reveals the complexity of the REV formation mechanism. IR spectroscopy, as a quick, cost-effective, and label-free technique provides valuable novel biochemical insight and might be used complementary to traditional omics approaches on EVs

Purification of extracellular vesicles by size-exclusion chromatography using cross-linked agarose gels: the role of pore size in lipoprotein contamination

Extracellular vesicles (EVs) are pivotal in intercellular communication and hold promise for diagnostic and therapeutic applications. Their isolation from complex biological fluids like plasma, however, poses significant challenges. This study examined the impact of pore size in agarose gels on the yield and purity of EVs isolated by Size-Exclusion Chromatography (SEC). We systematically compared the performance of agarose gels with different degrees of crosslinking (Sepharose CL-2B, CL-4B, and CL-6B) using both HPLC-SEC and gravity-based protocols, utilizing the supernatant from isolated human platelets redispersed in an additive solution containing plasma as the source of EVs. The experimental design involved the precise determination of EV elution volumes, identification of EV fractions based on associated markers, and assessment of co-eluted plasma constituents. The findings indicated that smaller pore sizes of the gels led to increased co-elution of lipoproteins with EVs. Yet, they also enhanced EV yields, highlighting a trade-off between yield and purity. Specifically, the CL-6B gel, with the smallest pore size, demonstrated the highest EV yield and lipoprotein contamination among the compared gels. Consequently, the selection of SEC gel for EV purification should be tailored to the requirements of the subsequent analysis, balancing yield and purity considerations

Particle Size Distribution of Bimodal Silica Nanoparticles: A Comparison of Different Measurement Techniques

Silica nanoparticles (SNPs) belong to the most widely produced nanomaterials nowadays. Particle size distribution (PSD) is a key property of SNPs that needs to be accurately determined for a successful application. Many single particle and ensemble characterization methods are available for the determination of the PSD of SNPs, each having different advantages and limitations. Since most preparation protocols for SNPs can yield bimodal or heterogeneous PSDs, the capability of a given method to resolve bimodal PSD is of great importance. In this work, four different methods, namely transmission electron microscopy (TEM), dynamic light scattering (DLS), microfluidic resistive pulse sensing (MRPS) and small-angle X-ray scattering (SAXS) were used to characterize three different, inherently bimodal SNP samples. We found that DLS is unsuitable to resolve bimodal PSDs, while MRPS has proven to be an accurate single-particle size and concentration characterization method, although it is limited to sizes above 50 nm. SAXS was found to be the only method which provided statistically significant description of the bimodal PSDs. However, the analysis of SAXS curves becomes an ill-posed inverse mathematical problem for broad size distributions, therefore the use of orthogonal techniques is required for the reliable description of the PSD of SNPs