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Representative TEM micrographs of PVC particles as obtained for PVC-2 with scale bar = 2 μm (A) and PVC-3 with scale bar = 5 μm (C) and their corresponding number-weighted distributions of area-equivalent diameters (B and D), bin size = 10 nm.
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Line-start incremental centrifugal liquid sedimentation (disc-CLS) is a powerful method to determine particle size based on the principles of Stokes' law. Because several of the input quantities of the Stokes equation cannot be easily determined for this case of a rotating disc, the disc-CLS approach relies on calibrating the sedimentation time sca...
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... different sodium polytungstate solutions were prepared from a stock solution (TC-Tungsten Compounds GmbH, Grub am Forst, DE) which had an assigned concentration of (846.6 ± 0.1) g/kg and a density of 3.01 g/cm 3 . The density and viscosity of sodium polytungstate as a function of mass concentration are shown in Figure S1. To assess method precision, experiments were carried out according to a method validation approach, i.e., a total of 15 independent test samples were measured over 5 days with three replicates per day. ...
Context 2
... contrast to the findings of McDonald, 11 even prolonged exposure to the electron beam and the high vacuum, which lasted up to five times longer than normally applied, did not alter the external morphology of the PVC particles (data not shown). Figure 1 shows representative TEM images of PVC-2 and PVC-3 particles along with their number-weighted PSDs of area-equivalent diameters. Both sets of images were processed using a manual grayscale thresholding method. ...
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Citations
... These behaviors and properties of particles in suspensions could be characterized by different technologies, such as dynamic light scattering (DLS) [8], electrophoresis [9], sedimentation [10], acoustic attenuation [11], and electroacoutics [12]. And, all these technologies need the shear viscosity of the carrier liquids to obtain results. ...
It needs to input the shear viscosity of carrier liquids during analyzing behaviors and properties of micron and nano-meter particles in suspensions, but it is impossible to adopt effective values for shear-thinning liquids. A method was brought forward to estimate shear viscosity based on longitudinal viscosity from acoustic attenuation and speed velocity of these liquids; then, influences of shear viscosity on both particle size distribution (PSD) and zeta potential were researched during attenuation and electroacoustic analysis of submicron ceria particles in these liquids. It was found that the aqueous carrier liquids with sodium carboxymethyl cellulose (CMC) determined by the new method should be Newtonian liquids with shear viscosity between 1.15 and 1.25 mPa·s, although they showed shear thinning and had much higher shear viscosity in limited range of shear rate during viscometer testing. Input values of shear viscosity had great influences on both PSD and zeta potential results, where d50 and zeta potential had deviations as high as 5 times and 27 times, respectively. And, the deviations could be reduced to 10 to 20% when the shear viscosity of pure water was adopted. These deviations were discussed based on visco-inertial attenuation and electroacoustic theories, and these results could provide a new way to research dispersion behaviors and properties of particles in shear-thinning liquids.
... All measurements were performed at rotational speed of 20,000 rpm and injection volume of 100 μL. Before each sample injection, the instrument was calibrated using polyvinylchloride (PVC) particles of nominal diameter of 263 nm and density of 1.39 g/cm 3 (CPS Instruments) [33]. ...
Control over the agglomeration state of manufactured particle systems for drug and oligonucleotide intracellular delivery is paramount to ensure reproducible and scalable therapeutic efficacy. Ultrasonication is a well-established mechanism for the deagglomeration of bulk powders in dispersion. Its use in manufacturing requires strict control of the uniformity and reproducibility of the cavitation field within the sample volume to minimise within-batch and batch-to-batch variability. In this work, we demonstrate the use of a reference cavitating vessel which provides stable and reproducible cavitation fields over litre-scale volumes to assist the controlled deagglomeration of a novel non-viral particle-based plasmid delivery system. The system is the Nuvec delivery platform, comprising polyethylenimine-coated spiky silica particles with diameters of ∼200 nm. We evaluated the use of controlled cavitation at different input powers and stages of preparation, for example before and after plasmid loading. Plasmid loading was confirmed by X-ray photoelectron spectroscopy and gel electrophoresis. The latter was also used to assess plasmid integrity and the ability of the particles to protect plasmid from potential degradation caused by the deagglomeration process. We show the utility of laser diffraction and differential centrifugal sedimentation in quantifying the efficacy of product de-agglomeration in the microscale and nanoscale size range respectively. Transmission electron microscopy was used to assess potential damages to the silica particle structure due to the sonication process.
... However, the fractionation becomes greatly complicated if the size distribution is too broad. Spherical nanocarriers with narrower size distribution and densities are better candidates for CLS measurements [32,33]. Samples also must not undergo any changes, chemically or physically, in the suspension during sedimentation. ...
There has been an increasing demand for the development of nanocarriers targeting multiple diseases with a broad range of properties. Due to their tiny size, giant surface area and feasible targetability, nanocarriers have optimized efficacy, decreased side effects and improved stability over conventional drug dosage forms. There are diverse types of nanocarriers that have been synthesized for drug delivery, including dendrimers, liposomes, solid lipid nanoparticles, polymersomes, polymer–drug conjugates, polymeric nanoparticles, peptide nanoparticles, mi-celles, nanoemulsions, nanospheres, nanocapsules, nanoshells, carbon nanotubes and gold na-noparticles, etc. Several characterization techniques have been proposed and used over the past few decades to control and predict the behavior of nanocarriers both in vitro and in vivo. In this review, we describe some fundamental in vitro, ex vivo, in situ and in vivo characterization methods for most nanocarriers, emphasizing their advantages and limitations, as well as the safety, regulatory and manufacturing aspects that hinder the transfer of nanocarriers from the laboratory to the clinic. Moreover, integration of artificial intelligence with nanotechnology, as well as the advantages and problems of artificial intelligence in the development and optimization of nanocarriers, are also discussed, along with future perspectives.
... However, the fractionation becomes greatly complicated if the size distribution is too broad. Spherical nanocarriers with narrower size distribution and densities are better candidates for CLS measurements [32,33]. Samples also must not undergo any changes, chemically or physically, in the suspension during sedimentation. ...
There has been an increasing demand for the development of nanocarriers targeting multiple diseases with a broad range of properties. Due to their tiny size, giant surface area and feasible targetability, nanocarriers have optimized efficacy, decreased side effects and improved stability over conventional drug dosage forms. There are diverse types of nanocarriers that have been synthesized for drug delivery, including dendrimers, liposomes, solid lipid nanoparticles, polymersomes, polymer–drug conjugates, polymeric nanoparticles, peptide nanoparticles, micelles, nanoemulsions, nanospheres, nanocapsules, nanoshells, carbon nanotubes and gold nanoparticles, etc. Several characterization techniques have been proposed and used over the past few decades to control and predict the behavior of nanocarriers both in vitro and in vivo. In this review, we describe some fundamental in vitro, ex vivo, in situ and in vivo characterization methods for most nanocarriers, emphasizing their advantages and limitations, as well as the safety, regulatory and manufacturing aspects that hinder the transfer of nanocarriers from the laboratory to the clinic. Moreover, integration of artificial intelligence with nanotechnology, as well as the advantages and problems of artificial intelligence in the development and optimization of nanocarriers, are also discussed, along with future perspectives.
... Before each sample injection, the instrument was calibrated using PS particles of a diameter of 520 nm ± 5 % and density of 1.05 g/cm 3 ± 3.5 % (CPS Instruments). 50 Samples were typically diluted 1000 times in ultrapure water, but the concentration was optimized on a sample-by-sample basis. Full details of the measurement parameters can be found Table S2 of the Supporting Information. ...
Laser diffraction (LD) is a well-established tool for the measurement of particle size distribution. Recently, its demand and use for the measurement of complex biological systems have increased. Among the challenges that these types of samples present, there is the presence of multiple particle populations whose modal size may span across several orders of magnitude. In this study, we assessed the accuracy of LD for the measurement of the modal diameter of both single and mixed populations of polystyrene particles with diameters ranging from 60 nm to 40 μm. We discuss the application of different available algorithms to the analysis of the data and their impact on the measurement results. Independent methods were applied to guide the selection of the algorithms and validate the measured size distributions. We found that the modal diameters of the particle size distribution measured by LD for the mixed suspension was accurate within 2 % for particles larger than 1 μm and generally within 25 % for the particles tested. Method repeatability was found to be robust, with deviations below 1%. The method was also found to be useful for estimating the relative concentration of the particle populations in the mixed samples. This study provides confidence in the use of LD for the measurement of complex multimodal colloidal samples.
... These values should be compared to the stated size of 483 nm and stated density of 1.385 g/cm 3 from the certificate of analysis, representing discrepancies of 1.4 and 2.5%, respectively. Similar agreement is found with the work of Kestens, et al. 11 and Neumann, et al. 12 Given the specifications of the PVC particle size standard, we estimate that the silica density lies within the range 1.97 to 2.07 g/cm 3 . ...
Physically meaningful characterization of irregularly shaped particles continues to present substantial challenges to the experimentalist. "Equivalent diameters" based on experimental techniques such as static and dynamic light scattering or sedimentation have proliferated to the point that they are often no longer recognized as equivalent. This study demonstrates the use of dual-fluid disk centrifuge photosedimentometry coupled with rheological measurements of viscosity to provide direct insights into both the average mass of a structured particle size distribution and the average hydrodynamic diameter.
... Calibrating the sedimentation time scale of disc-type CLS instruments is common practice as it is the most user-friendly approach to cope efficiently and quantitatively with the combined effect of several input quantities (i.e., η, ρ l , S) which continuously change throughout a measurement sequence, due to the injection of test samples and calibrant samples. However, calibration poses risks when calibrants are not well characterized [27,28]. Other advantages that makes the cuvette-type CLS method (further referred to as cuvette-CLS) standing out compared to the disc-CLS method is the absence of a density gradient which makes it possible to analyze the particles in their original state and dispersant. ...
Silica nanoparticles display many unique physicochemical properties that make them desirable for use in a wide variety of consumer products and composite materials. Accurately measuring the size of these nanoparticles is important for achieving the desired nanoscale functionality of the final product and for regulatory compliances. This study covers the validation of a centrifugal liquid sedimentation method for accurate measurement of the Stokes diameter of silica particles with a near-spherical shape and dimensions in the nanometer and sub-nanometer scale range. The validated method provided unbiased results in the range of 50 nm to 200 nm, with a lower limit of detection of ≤20 nm. The relative standard uncertainties for precision, quantified in terms of repeatability and day-to-day variation, ranged from 0.2% to 1.0% and from <0.1% to 0.5%, respectively. The standard uncertainty for trueness was assessed at 4.6%. Within its working range, the method was found robust with respect to the type of cuvette, light factor, operator, and for defining the meniscus of the sample suspension. Finally, a relative expanded measurement uncertainty of 10% confirmed the satisfactory performance of the method.
... These characteristics are highly demanded in fields such as electrode modification and biosensors development [16]. In recent years, many applications for modifications with CB have appeared in literature, such as the modification of DNA biosensors [16], plastic films [17,18], and nano-film electrosensors [19][20][21][22]. ...
Diclofenac (DIC) is a non-steroidal anti-inflammatory drug of wide use around the world. Electroanalytical methods display a high analytical potential for application in pharmaceutical samples but the drawbacks concerning electrode fouling and reproducibility are of major concern. Henceforth, the aim of this work was to propose the use of alternative low-cost carbon black (CB) and ionic liquid (IL) matrix to modify the surface of pencil graphite electrodes (PGE) in order to quantify DIC in raw materials, intermediates, and final products, as well as in stability assays of tablets. The proposed method using CB+IL/PGE displayed good recovery (99.4%) as well as limits of detection (LOD) of 0.08 µmol L-1 and limits of quantification (LOQ) of 0.28 µmol L −1. CB+IL/PGE response was five times greater than the unmodified PGE. CB+IL-PGE stands as an interesting alternative for DIC assessment in different pharmaceutical samples.
... Thus, for the DCS (DCS/DLS) method, precise knowledge of the particle size and size distribution as well as the density of the material is essential for use in laboratory conditions. The major contribution to DCS uncertainty is composed of the uncertainties on the size and density of the calibrants [30]. Method trueness for the measurement of nanoparticle concentration was found to be around 30%. ...
The industrial exploitation of high value nanoparticles is in need of robust measurement methods to increase the control over product manufacturing and to implement quality assurance. InNanoPart, a European metrology project responded to these needs by developing methods for the measurement of particle size, concentration, agglomeration, surface chemistry and shell thickness. This paper illustrates the advancements this project produced for the traceable measurement of nanoparticle number concentration in liquids through small angle X-ray scattering (SAXS) and single particle inductively coupled plasma mass spectrometry (spICPMS). It also details the validation of a range of laboratory methods, including particle tracking analysis (PTA), dynamic light scattering (DLS), differential centrifugal sedimentation (DCS), ultraviolet visible spectroscopy (UV-vis) and electrospray-differential mobility analysis with a condensation particle counter (ES-DMA-CPC). We used a set of spherical gold nanoparticles with nominal diameters between 10 nm and 100 nm and discuss the results from the various techniques along with the associated uncertainty budgets.
... Calibration of the instrument was performed before each sample injection by using polyvinyl chloride calibration particles with nominal Stokes' modal diameter of 237 nm and density of 1.385 g/cm 3 provided by the instrument manufacturer. The uncertainties in the size and density of the calibrant were set at 5 and 3.5%, respectively, according to the work by Kestens et al. 27 The injected sample volume was measured by weighing the syringe containing the sample before and after each injection and assuming a density of the sample solution of 1 g/cm 3 . For the data analysis, recalling that the spectral intensity peak of the laser instrument is at 405 nm, the refractive index and absorption of the gold particles were set to 1.62 and 1.95, respectively, and the average refractive index and viscosity of the gradient at 1.357 and 1.3 mPa·s, respectively. ...
Measuring the number concentration of colloidal nanoparticles is critical for assessing reproducibility, compliance with regulation and performing risk assessments of nanoparticle-enabled products. For nanomedicines, their number concentration directly relates to their dose. However, the lack of relevant reference materials and established traceable measurement approaches make the validation of methods for nanoparticle number concentration difficult. Furthermore, commercial products often exhibit agglomeration, but guidelines for dealing with non-ideal samples are scarce. We have compared the performance of five benchtop measurement methods for the measurement of colloidal number concentration in presence of different levels of agglomeration. The methods are: UV-Visible spectroscopy, differential centrifugal sedimentation (DCS), dynamic light scattering (DLS), particle tracking analysis (PTA) and single particle inductively coupled plasma mass spectrometry (spICP-MS). We find that both ensemble and particle-by-particle methods are in close agreement for monodisperse nanoparticle samples and three methods are within 20% agreement for agglomerated samples. We discuss the sources of measurement uncertainties, including how particle agglomeration affects measurement results. This work validate and expands the toolbox of methods available for the measurement of real-world nanoparticle products.
