Synthesis Processing Condition Optimization of Citrate Stabilized Superparamagnetic Iron Oxide Nanoparticles using Direct Co-Precipitation Method

Superparamagnetic iron oxide nanoparticles (SPION) are commonly prepared by co-precipitation, a convenient and high yield producing method. However, this method produces large particles and wide size distribution. Thus, this study aims to optimize and determine the processing condition during the direct co-precipitation synthesis of citrate stabilized SPION (SPION-C). Processing conditions were optimized to achieve the suitable hydrodynamic size and zeta potential; measured straight after preparation, at weeks 3, 10, and 30. Characterization of optimized SPION and SPION-C was done by Fourier transform infrared spectroscopy (FTIR), fluorescence spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The optimized processing condition (stirring speed of 9000 rpm, stabilizer concentration of 1.006 M, and a 90oC stabilizer adsorption temperature), resulted in suitable SPION-C with a hydrodynamic size of 25.58 ± 7 nm, and zeta potential value of -50.8 ± 3.9. Particles with an almost sphere morphology with below 20 nm size were shown by TEM. The XRD analysis presented magnetite phase with a 2.79 nm core size which indicated the formation of stabilized SPION. The maximum excitation and emission wavelength of SPION after stabilization were proved to be uninterrupted by fluorescence spectroscopy. Further FTIR results supported the successful conjugation of citrate onto SPION. Highly stable and crystalline SPION-C were successfully produced through an optimized processing condition using direct co-precipitation. The obtained SPION-C conveyed desired nanoparticle size with narrow size distribution and stability for 30 weeks of storage at 4oC.

Multifunctionality of Nanosized Calcium Apatite Dual-Doped with Li+/Eu3+ Ions Related to Cell Culture Studies and Cytotoxicity Evaluation In Vitro

Li+/Eu3+ dual-doped calcium apatite analogues were fabricated using a microwave stimulated hydrothermal technique. XRPD, FT-IR, micro-Raman spectroscopy, TEM and SAED measurements indicated that obtained apatites are single-phased, crystallize with a hexagonal structure, have similar morphology and nanometric size as well as show red luminescence. Lithium effectively modifies the local symmetry of optical active sites and, thus, affects the emission efficiency. Moreover, the hydrodynamic size and surface charge of the nanoparticles have been extensively studied. The protein adsorption (lysozyme, LSZ; bovine serum albumin, BSA) on the nanoparticle surface depended on the type of cationic dopant (Li+, Eu3+) and anionic group (OH−, Cl−, F−) of the apatite matrix. Interaction with LSZ resulted in a positive zeta potential, and the nanoparticles had the lowest hydrodynamic size in this protein medium. The cytotoxicity assessment was carried out on the human osteosarcoma cell line (U2OS), murine macrophages (J774.E), as well as human red blood cells (RBCs). The studied apatites were not cytotoxic to RBCs and J774.E cells; however, at higher concentrations of nanoparticles, cytotoxicity was observed against the U2OS cell line. No antimicrobial activity was detected against Gram-negative bacteria with one exception for P. aeruginosa treated with Li+-doped fluorapatite.

Dispersion Behavior of Blast Furnace Sludge for Valuable Metal Recovery

Blast furnace sludge, which comes from the iron making process, contains many valuable materials including iron, carbon, and zinc, etc. Because a cohesive agent is added during filtration, fine sludge particles are agglomerated together. Therefore, This makes it necessary to disperse the sludge in solution before separating or recovering valuable materials. In this study, the effects of solid/liquid (g/L) ratio, ultrasonic dispersion conditions, the pH of solvent, and the concentration of dispersant on the dispersion of sludge were investigated by measuring the interfacial properties (zeta potential and hydrodynamic size) of sludge particles. High absolute value of zeta potential and small hydrodynamic size suggests that the sludge particles in the solution presents good dispersion. The absolute value of zeta potential increased gradually at high solid/liquid ratio and ultrasonic dispersion intensity. But when the sludge in solution was dispersed for more than 30 minutes, the absolute value of the zeta potential decreased due to increasing contact and interaction between the particles. Optimal dispersion operations were conducted and when the pH of the solution was adjusted to 11, the zeta potential value was measured to be -44.8 mV. This means that the sludge formed the most stable dispersed phase. The lowest zeta potential was measured to be -46.4 mV with the addition of sodium hexametaphosphate (NaPO3)6 in the solution. It is thought that the sodium hexametaphosphate reduced ionic strength by removing alkali metal ions from the solution of sludge.

Stem Cell-Engineered Nanovesicles Exert Proangiogenic and Neuroprotective Effects

As a tissue regeneration strategy, the utilization of mesenchymal stem cells (MSCs) has drawn considerable attention. Comprehensive research using MSCs has led to significant preclinical or clinical outcomes; however, improving the survival rate, engraftment efficacy, and immunogenicity of implanted MSCs remains challenging. Although MSC-derived exosomes were recently introduced and reported to have great potential to replace conventional MSC-based therapeutics, the poor production yield and heterogeneity of exosomes are critical hurdles for their further applications. Herein, we report the fabrication of exosome-mimetic MSC-engineered nanovesicles (MSC-NVs) by subjecting cells to serial extrusion through filters. The fabricated MSC-NVs exhibit a hydrodynamic size of ~120 nm, which is considerably smaller than the size of MSCs (~30 μm). MSC-NVs contain both MSC markers and exosome markers. Importantly, various therapeutic growth factors originating from parent MSCs are encapsulated in the MSC-NVs. The MSC-NVs exerted various therapeutic effects comparable to those of MSCs. They also significantly induced the angiogenesis of endothelial cells and showed neuroprotective effects in damaged neuronal cells. The results collectively demonstrate that the fabricated MSC-NVs can serve as a nanosized therapeutic agent for tissue regeneration.

Structural and Energetic Characterization of the Denatured State from the Perspectives of Peptides, the Coil Library, and Intrinsically Disordered Proteins

The α and polyproline II (PPII) basins are the two most populated regions of the Ramachandran map when constructed from the protein coil library, a widely used denatured state model built from the segments of irregular structure found in the Protein Data Bank. This indicates the α and PPII conformations are dominant components of the ensembles of denatured structures that exist in solution for biological proteins, an observation supported in part by structural studies of short, and thus unfolded, peptides. Although intrinsic conformational propensities have been determined experimentally for the common amino acids in short peptides, and estimated from surveys of the protein coil library, the ability of these intrinsic conformational propensities to quantitatively reproduce structural behavior in intrinsically disordered proteins (IDPs), an increasingly important class of proteins in cell function, has thus far proven elusive to establish. Recently, we demonstrated that the sequence dependence of the mean hydrodynamic size of IDPs in water and the impact of heat on the coil dimensions, provide access to both the sequence dependence and thermodynamic energies that are associated with biases for the α and PPII backbone conformations. Here, we compare results from peptide-based studies of intrinsic conformational propensities and surveys of the protein coil library to those of the sequence-based analysis of heat effects on IDP hydrodynamic size, showing that a common structural and thermodynamic description of the protein denatured state is obtained.

Green Synthesis of Reduced Graphene Oxide Using Root Extracts of Asparagus racemosus

Background: The root extracts of Asparagus racemosus (shatamuli) has been used as benign as reducing agent to reduce graphene oxide (GO) to reduced form of graphene oxide (rGO). The root extract used as a green reducing agent that is non-toxic, eco-friendly and natural therapeutic. Methods: The formation of rGO was identified using XRD, FTIR, TEM and EDX techniques. Results: The DLS and Zeta potential data revealed that the hydrodynamic size of these rGO is lower than 200 nm with optimal charge. Conclusion: These results may be useful for the use of GO as probe in biomedical research where the plant species has known biomedical applications.

Bioassay-guided optimization of lipid-based erythromycin microparticles

Purpose: To optimize erythromycin microparticles by in vitro bioassay methods based on its antibacterial activity. Methods: The microparticles were produced by high shear homogenization. The effects of different lipid-to-surfactant ratios were studied. The hydrodynamic size of the different batches was evaluated using dynamic light scattering while bioactive drug load per batch was assessed in agar using bioassay methods. The antimicrobial activities of selected batches were tested ex vivo by determination of reduction in bacteraemia following administration of the microparticles to infected animals. Results: All batches had particles with hydrodynamic sizes < 8.5 microns. Batch 7 with a 2: 5: 2.5 (drug: surfactant: stearic acid) ratio, represents the optimized batch with a hydrodynamic size of 2281 nm, a bioactive drug loading capacity (BLC) of 4.67 ± 0.70 % and bioactive drug entrapment efficiency (BEE) of 10.51 %. The “microparticle MIC” against Staphylococcus aureus was 1.74 x 10-3 μg/ml. Despite containing lower amounts of erythromycin than the pure sample, the microparticles achieved comparable reduction in bacteraemia, with the optimized batch exhibiting lower variation in bacteraemia than the pure drug. Conclusion: Erythromycin microparticles have been successfully optimized with the aid of bioassay methods which has the advantage that only the bioactive drug concentration is factored in. This method eliminates problems posed by inadequate or non-discriminating chemical assay methods. Keywords: Microparticles, Erythromycin, Gastrointestinal, Bioavailability Antimicrobial, Bioactivity, Encapsulation

Diblock, Triblock and Cyclic Amphiphilic Copolymers with CO2 Switchability: Effects of Topology

The combination of topology and CO2 switchability could provide new options for amphiphilic copolymers. Cyclic molecules supply novel topologies, and CO2 switching provides stimulus responsiveness. Cyclic poly(2–(diethylamino)ethyl methacrylate)–b–poly(ethylene oxide) and their corresponding block copolymers were prepared from poly(ethylene oxide) and 2–(diethylamino)ethyl methacrylate via atom transfer radical polymerization and Keck allylation with a Hoveyda–Grubbs catalyst. Changes in conductivity, surface activity, and hydrodynamic size were examined to illustrate the switchability of the produced amphiphilic copolymers upon contact with CO2 in the presence of water. The reversible emulsification and switchable viscosity behaviors of the copolymers were also demonstrated.