Efficiency analysis of helium-cooled MAS DNP: case studies of surface-modified nanoparticles and homogeneous small-molecule solutions

DNP enhancement, paramagnet-induced quenching/depolarization and build-up times are studied in a heterogeneous catalyst between 30 and 100 K. He-cooled MAS DNP at 30 K provides up to 100-fold better time performance than N2-cooled MAS DNP at 90 K.

Characterization and Nanofluid Stability of CoFe2O4-APTES and CoFe2O4-PVA Nanoparticles

Nanofluid contains nanoparticles that enhanced the property of the base fluid. However, the separating layer between the nanoparticles and base fluids may interfere the nanofluids performance. Studies have been made that surface modification of nanoparticles may improve the dispersion of nanoparticles in base fluids. This paper reports the study of the colloidal stability of surface modified nanoparticles using a polymer and an amino-silane. The nanoparticles were prepared by one-step and two-step methods using cobalt iron oxide nanoparticles with brine solution and deionized water as the base fluids. Functionalization by surface modification of the nanoparticles to enhance the nanofluids stability was carried out using (3-aminopropyl) triethoxysilane (APTES) and polyvinyl alcohol (PVA). Characterization using Fourier Transform Infrared (FTIR), Field Emission Scanning Electron Microscope (FESEM) and X-ray Powder Diffraction (XRD) were performed to study the functionality and morphology of the synthesized nanoparticles. The extra IR peaks such as Si-O-Si at 1063 cm-1 for CoFe2O4-APTES and C=O at 1742 cm-1 for CoFe2O4-PVA showed that there are additional elements in the cobalt ferrite due to functionalization. The size of synthesized CoFe2O4-APTES ranged between 15.99 nm to 26.89 nm while CoFe2O4-PVA is from 25.70 nm to 54.16 nm. The stability of the nanofluid were determined via zeta potential measurements. CoFe2O4-APTES nanofluid has zeta potential of -35.7 mV compared to CoFe2O4-PVA at -15.5 mV.

Improvement of stem cell-derived exosome release efficiency by surface-modified nanoparticles

Background Mesenchymal stem cells (MSCs) are pluripotent stromal cells that release extracellular vesicles (EVs). EVs contain various growth factors and antioxidants that can positively affect the surrounding cells. Nanoscale MSC-derived EVs, such as exosomes, have been developed as bio-stable nano-type materials. However, some issues, such as low yield and difficulty in quantification, limit their use. We hypothesized that enhancing exosome production using nanoparticles would stimulate the release of intracellular molecules. Results The aim of this study was to elucidate the molecular mechanisms of exosome generation by comparing the internalization of surface-modified, positively charged nanoparticles and exosome generation from MSCs. We determined that Rab7, a late endosome and auto-phagosome marker, was increased upon exosome expression and was associated with autophagosome formation. Conclusions It was concluded that the nanoparticles we developed were transported to the lysosome by clathrin-mediated endocytosis. additionally, entered nanoparticles stimulated that autophagy related factors to release exosome from the MSC. MSC-derived exosomes using nanoparticles may increase exosome yield and enable the discovery of nanoparticle-induced genetic factors.

Improvement of stem cell-derived exosome release efficiency by surface modified nanoparticles

Background: Mesenchymal stem cells (MSCs) are pluripotent stromal cells that release extracellular vesicles (EVs). EVs contain various growth factors and antioxidants that can positively affect the surrounding cells. Nanoscale MSC-derived EVs, such as exosomes, have been developed as bio-stable nano-type materials. However, some issues, such as low yield and difficulty in quantification, limit their use. We hypothesized that enhancing exosome production using nanoparticles would stimulate the release of intracellular molecules. Results: The aim of this study was to elucidate the molecular mechanisms of exosome generation by comparing the internalization of surface-modified, positively charged nanoparticles and exosome generation from MSCs. We determined that Rab7, a late endosome and auto-phagosome marker, was increased upon exosome expression and was associated with autophagosome formation. Conclusions: It was concluded that the nanoparticles we developed were transported to the lysosome by clathrin-mediated endocytosis. additionally, entered nanoparticles stimulated that autophagy related factors to release exosome from the MSC. MSC-derived exosomes using nanoparticles may increase exosome yield and enable the discovery of nanoparticle-induced genetic factors.

Improvement of stem cell-derived exosome release efficiency by surface-modified nanoparticles

Background: Mesenchymal stem cells (MSCs) are pluripotent stromal cells that release extracellular vesicles (EVs). EVs contain various growth factors and antioxidants that can positively affect the surrounding cells. Nanoscale MSC-derived EVs, such as exosomes, have been developed as bio-stable nano-type materials. However, some issues, such as low yield and difficulty in quantification, limit their use. We hypothesized that enhancing exosome production using nanoparticles would stimulate the release of intracellular molecules. Results: The aim of this study was to elucidate the molecular mechanisms of exosome generation by comparing the internalization of surface-modified, positively charged nanoparticles and exosome generation from MSCs. We determined that Rab7, a late endosome and auto-phagosome marker, was increased upon exosome expression and was associated with autophagosome formation. Conclusions: It was concluded that the nanoparticles we developed were transported to the lysosome by clathrin-mediated endocytosis. additionally, entered nanoparticles stimulated that autophagy related factors to release exosome from the MSC. MSC-derived exosomes using nanoparticles may increase exosome yield and enable the discovery of nanoparticle-induced genetic factors.

Synthesis and Characterization of a New Surface-Modified Nanoparticle Using Fluoroalkanoic Acids as a Wettability Alteration Agent

Previously, condensate banking removal in gas reservoir is mitigated using chemical treatments to alter the wettability of the near-wellbore region. However, this technique performed unsatisfactorily as it reduces the surface free energy and affects the gas relative permeability negatively. Hence, alternative surface-modified nanoparticles using fluorine-based chemicals were developed as wettability alteration agents since fluorine exhibits a high degree of liquid repellency and nanoparticles introduce high surface roughness. The newly synthesized surface-modified nanoparticles were characterized using FTIR, DLS, FESEM, and TGA. FTIR results highlight the characteristic absorption of Si-O-C group at peak 1105 and 1106 cm-1 in both fluoroalkanoic acids, demonstrating that fluorochemical molecules have been successfully coated onto silica nanoparticles. Nanoparticle sizes measured by DLS reported higher value than FESEM due to agglomeration, and the DLS measurement was done in hydrodynamic conditions. TGA analysis reveals decomposition at temperature between 100 and 150°C, indicating that these surface-modified nanoparticles can be utilized in an environment below 100°C. Higher decomposition was perceived on PFNA-modified nanoparticles as a thicker coating of PFNA is shrouding the silica nanoparticles compared to PFOA. Implications of the results will path the way for future research direction in using fluorine-based surface-modified nanoparticles as wettability alteration agents.

Surface modified polymeric nanoparticles for drug delivery: preparation and applications

: Nanotechnology is one of the emerging fields in the drug delivery for targeting the drug to the site of action. The polymeric nanoparticles as drug delivery systems have gained importance for the last few decades. They offer advantages over liposomes, dendrimers, emulsions etc. Surface engineering of polymeric nanoparticles is widely utilized to effectively target the cells in various diseases such as cancer, HIV infection. Surface modified nanoparticles offer various advantages such as targeted drug delivery, reduction in side effects, dose reductionand improved therapeutic efficacy. Moreover, they can aid in improving physical and biochemical properties, pharmacokinetic and pharmacodynamic profiles of drug. Surface modified polymeric nanoparticles can provide targeted delivery of drugs into specific cells, especially when targets are intracellular localized. This approach would be more advantageous for the delivery of various anticancer, anti inflammatory, anti HIV drugs for more effective therapy. This review focuses on the techniques used for fabrication of polymeric nanoparticles, material used for surface modification and their applications.

Antimicrobial Activity of Isoniazid in Conjugation with Surface-Modified Magnetic Nanoparticles against Mycobacterium tuberculosis and Nonmycobacterial Microorganisms

Isoniazid, the choice antitubercular agent, has only been employed against Mycobacterium tuberculosis. This study evaluated if the enzyme-mimetic activities of magnetic nanoparticles could accelerate the activation process of isoniazid against mycobacterial and, more importantly, non-mycobacterial microorganisms. First, magnetic nanoparticles were synthesized and coated by lipoamino acid; then, isoniazid was conjugated to synthesized nanoparticles. Antibacterial activities of nanoconjugated isoniazid were evaluated against Mycobacterium tuberculosis and four Gram-positive and Gram-negative nonmycobacterial strains through a microdilution broth process. Results showed that the required amount of isoniazid against Mycobacterium tuberculosis would decrease to 44.8% and 16.7% in conjugation with naked and surface-modified magnetic nanoparticles, respectively. Also, 32 μg/mL and 38 μg/mL of isoniazid in conjugation with naked and surface-modified nanoparticles, respectively, could prevent the growth of Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Hence, the vicinity of magnetic nanoparticles with isoniazid could declare promising aspects of isoniazid antibacterial capabilities.