Viscosity gradient as a novel mechanism for the centrifugation-based separation of nanoparticles.
Ontology highlight
ABSTRACT:
SUBMITTER: Qiu P
PROVIDER: S-EPMC3361505 | biostudies-literature | 2011 Nov
REPOSITORIES: biostudies-literature
Publications
Viscosity gradient as a novel mechanism for the centrifugation-based separation of nanoparticles.
Advanced materials (Deerfield Beach, Fla.) 20110926 42
Similar Datasets
Project description:This article describes the stabilization and postsynthetic separation of gold nanostars (AuNS) synthesized with a morpholine-based Good's buffer, 3-(N-morpholino)propanesulfonic acid. Resuspension of AuNS in ultrapure water improved the shape stability of the particles over 30 days. We demonstrated the sorting of nanostars via rate-zonal centrifugation through a linear sucrose gradient based on branch length and number. We determined that one round of centrifugation was sufficient for separation. Also, we improved the structural homogeneity and stability of the nanoparticles through the optimization of the storage conditions and established a robust method to sort AuNS based on size and shape.
| S-EPMC6641882 | biostudies-literature
Project description:Sustainable production and use of carbon nanotube (CNT)-enabled materials require efficient assessment of CNT environmental hazards, including the potential for CNT bioaccumulation and biomagnification in environmental receptors. Microbes, as abundant organisms responsible for nutrient cycling in soil and water, are important ecological receptors for studying the effects of CNTs. Quantification of CNT association with microbial cells requires efficient separation of CNT-associated cells from individually dispersed CNTs and CNT agglomerates. Here, we designed, optimized, and demonstrated procedures for separating bacteria (Pseudomonas aeruginosa) from unbound multiwall carbon nanotubes (MWCNTs) and MWCNT agglomerates using sucrose density gradient centrifugation. We demonstrate separation of protozoa (Tetrahymena thermophila) from MWCNTs, bacterial agglomerates, and protozoan fecal pellets by centrifugation in an iodixanol solution. The presence of MWCNTs in the density gradients after centrifugation was determined by quantification of 14C-labeled MWCNTs; the recovery of microbes from the density gradient media was confirmed by optical microscopy. Protozoan intracellular contents of MWCNTs and of bacteria were also unaffected by the designed separation process. The optimized methods contribute to improved efficiency and accuracy in quantifying MWCNT association with bacteria and MWCNT accumulation in protozoan cells, thus supporting improved assessment of CNT bioaccumulation.
| S-EPMC5132190 | biostudies-literature
Project description: Not available
| S-EPMC2656675 | biostudies-literature
Project description:Nanomedicine requires in-depth knowledge of nanoparticle-protein interactions. These interactions are studied with methods limited to large or fluorescently labelled nanoparticles as they rely on scattering or fluorescence-correlation signals. Here, we have developed a method based on analytical ultracentrifugation (AUC) as an absorbance-based, label-free tool to determine dissociation constants (KD), stoichiometry (Nmax), and Hill coefficient (n), for the association of bovine serum albumin (BSA) with gold nanoparticles. Absorption at 520 nm in AUC renders the measurements insensitive to unbound and aggregated proteins. Measurements remain accurate and do not become more challenging for small (sub-10 nm) nanoparticles. In AUC, frictional ratio analysis allows for the qualitative assessment of the shape of the analyte. Data suggests that small-nanoparticles/protein complexes significantly deviate from a spherical shape even at maximum coverage. We believe that this method could become one of the established approaches for the characterization of the interaction of (small) nanoparticles with proteins.
| S-EPMC5080432 | biostudies-literature
Project description:A general method of separating isotopes by centrifuging dissolved chemical compounds in a liquid is introduced. This technique can be applied to almost all elements and leads to large separation factors. The method has been demonstrated in several isotopic systems including Ca, Mo, O, and Li with single-stage selectivities of 1.046 to 1.067 per neutron mass difference (e.g., 1.43 in 40Ca/48Ca), which are beyond the capabilities of various conventional methods. Equations are derived to model the process, and the results agree with those of the experiments. The scalability of the technique has been demonstrated by a three-stage enrichment of 48Ca with a total 40Ca/48Ca selectivity of 2.43, and the scalability is more broadly supported through analogies to gas centrifuge, whereby countercurrent centrifugation can further multiply the separation factor by 5 to 10 times per stage in a continuous process. Optimal centrifuge conditions and solutions can achieve both high-throughput and highly efficient isotope separation.
| S-EPMC10337892 | biostudies-literature
Project description:We present a novel method for studying the integrated formation and separation of humins formed during the Brønsted acid-catalyzed conversion of fructose (here, at 90 °C with 20 wt % fructose and 5 wt % sulfuric acid). For the first time, we report the reaction carried out in situ during systematic centrifugation experiments, which allows combining humin formation and separation along with investigation of the phase behavior of humins. Analysis of the formed humin deposits employing scanning electron microscopy reveals deposits that are formed from a layer of monodisperse microspheres with a narrow diameter range of 0.9-1.9 μm. In the centrifugal force field, the microspheres partially coalesce, which increases with time and relative centrifugal force up to the formation of a thin and uniform layer of microspheres covering a continuous humin bulk phase with 80-90 μm thickness. These findings give evidence that humin spheres are highly viscous droplets rather than solid particles during formation. Our result is in line with the often-reported spherical and planar deposits formed during acidic carbohydrate conversion in technical systems and supports the development of strategies for deposit prevention, on the one hand, and humin preparation for material utilization, on the other hand.
| S-EPMC10870367 | biostudies-literature
Project description:ObjectiveTo investigate the efficacy of a new device for sperm preparation involving migration-gravity sedimentation without centrifugation (MIGLIS), compared with density-gradient centrifugation (DGC) for normozoospermic intrauterine insemination (IUI).DesignRetrospective cohort study.SettingNot applicable.PatientsA total of 10,318 cases of IUI (3,015 MIGLIS and 7,303 DGC) between October 2013 and September 2019.InterventionsNone.Main outcome measuresSperm analysis, subsequent pregnancy outcomes, and complications.ResultsMIGLIS was associated with a lower sperm recovery rate and fewer injected sperm compared with DGC. However, the overall pregnancy rates following MIGLIS and DGC were similar (MIGLIS 8.8%, DGC 9.3%). In a subanalysis according to age, the pregnancy rate was higher for MIGLIS among women 40-41 years of age (8.6% vs. 5.9%). Peritonitis was the only recorded complication, with similar frequencies in the MIGLIS and DGC groups (MIGLIS two cases, DGC four cases). No cases became severe, and all improved after antibiotic treatment. There were no cases of uterine cramping or pain symptoms.ConclusionsMIGLIS is a new sperm preparation method that does not require centrifugation. Its use was associated with pregnancy rates similar to those with DGC and a higher pregnancy rate in older women. MIGLIS is a novel sperm preparation method for selecting spermatozoa with high motility and good fertilization ability in patients undergoing IUI, in vitro fertilization, and intracytoplasmic sperm injection.
| S-EPMC8244315 | biostudies-literature
Project description:Deterministic Lateral Displacement (DLD) is a label-free particle sorting method that separates by size continuously and with high resolution. By combining DLD with electric fields (eDLD), we show separation of a variety of nano and micro-sized particles primarily by their zeta potential. Zeta potential is an indicator of electrokinetic charge-the charge corresponding to the electric field at the shear plane-an important property of micro- and nanoparticles in colloidal or separation science. We also demonstrate proof of principle of separation of nanoscale liposomes of different lipid compositions, with strong relevance for biomedicine. We perform careful characterization of relevant experimental conditions necessary to obtain adequate sorting of different particle types. By choosing a combination of frequency and amplitude, sorting can be made sensitive to the particle subgroup of interest. The enhanced displacement effect due to electrokinetics is found to be significant at low frequency and for particles with high zeta potential. The effect appears to scale with the square of the voltage, suggesting that it is associated with either non-linear electrokinetics or dielectrophoresis (DEP). However, since we observe large changes in separation behavior over the frequency range at which DEP forces are expected to remain constant, DEP can be ruled out.
| S-EPMC7702211 | biostudies-literature
Project description:Apoptotic vesicles (apoVs) are specific extracellular vesicles generated during apoptosis and play important roles in multiple physiological and pathophysiological settings. Here, we present a protocol using differential centrifugation to separate apoVs from human mesenchymal stem cells (MSCs) after induction of apoptosis. We describe how to characterize apoV size and morphology by nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM), and determination of specific biomarker expression by immunoblotting. Our protocol will be useful for preparing apoVs for further functional analysis. For complete details on the use and execution of this protocol, please refer to Zheng et al. (2021).
| S-EPMC9494288 | biostudies-literature
Project description:ObjectivesChemotherapeutic drugs induce senescence in cancer cells but, unlike replicative senescence or oncogene-induced senescence, do so rather inefficiently and depending on DNA damage. A thorough understanding of the biology of chemotherapy-induced senescent cells requires their isolation from a mixed population of adjacent senescent and non-senescent cancer cells.Materials and methodsWe have developed and optimized a rapid iodixanol (OptiPrep)-based gradient centrifugation system to identify, isolate and characterize doxorubicin (DXR)-induced senescent hepatocellular carcinoma (HCC) cells (HepG2 and Huh-7) in vitro.ResultsAfter cellular exposure to DXR, we used iodixanol gradient-based centrifugation to isolate and re-plate cells on collagen-coated flasks, despite their low or null proliferative capacity. The isolated cell populations were enriched for DXR-induced senescent HCC cells, as confirmed by proliferation arrest assay, and β-galactosidase and DNA damage-dependent γH2A.X staining.ConclusionsAnalysing pure cultures of chemotherapy-induced senescent versus non-responsive cancer cells will increase our knowledge on chemotherapeutic mechanisms of action, and help refine current therapeutic strategies.
| S-EPMC6869531 | biostudies-literature