A key enabling step in leveraging the properties of nanoparticles (NPs) is to explore new, simple, controllable, and scalable nanotechnologies for their syntheses. Among “wet” methods, cathodic corrosion has been used to synthesize catalytic aggregates with some control over their size and preferential faceting. Here, we report on a modification of the cathodic corrosion method for producing a range of nonaggregated nanocrystals (Pt, Pd, Au, Ag, Cu, Rh, Ir, and Ni) and nanoalloys (Pt50Au50, Pd50Au50, and AgxAu100–x) with potential for scaling up the production rate. The method employs poly(vinylpyrrolidone) (PVP) as a stabilizer in an electrolyte solution containing nonreducible cations (Na+, Ca2+), and cathodic corrosion of the corresponding wires takes place in the electrolyte under ultrasonication. The ultrasonication not only promotes particle–PVP interactions (enhancing NP dispersion and diluting locally high NP concentration) but also increases the production rate by a factor of ca. 5. Further increase in the production rate can be achieved through parallelization of electrodes to construct comb electrodes. With respect to applications, carbon-supported Pt NPs prepared by the new method exhibit catalytic activity and durability for methanol oxidation comparable or better than the commercial benchmark catalyst. A variety of AgxAu100–x nanoalloys are characterized by ultraviolet–visible absorption spectroscopy and high-resolution transmission electron microscopy. The protocol for NP synthesis by cathodic corrosion should be a step toward its further use in academic research as well as in its practical upscaling.

This study addressed the effect of contact sliding during stirring of a monoclonal antibody solution on protein aggregation, in particular, in the nanometer and micrometer size range. An overhead stirring set-up was designed in which the presence and magnitude of the contact between the stir bar and the container could be manipulated. A solution of 0.1 mg/mL of a monoclonal antibody (IgG) in phosphate buffered saline was stirred at 300 rpm at room temperature. At different time points, samples were taken and analyzed by nanoparticle tracking analysis, flow imaging microscopy, and size-exclusion chromatography. In contrast to non-contact-stirred and unstirred samples, the contact-stirred sample contained several-fold more particles and showed a significant loss of monomer. No increase in oligomer content was detected. The number of particles formed was proportional to the contact area and the magnitude of the normal pressure between the stir bar and the glass container. Extrinsic 9-(2,2-dicyanovinyl) julolidine fluorescence indicated a conformational change for contact-stirred protein samples. Presence of polysorbate 20 inhibited the formation of micron-sized aggregates. We suggest a model in which abrasion of the potentially destabilized, adsorbed protein leads to aggregation and renewal of the surface for adsorption of a fresh protein layer.

PurposeTo measure aggregate and particle formation in tumor necrosis factor-alpha (TNF-α) inhibitors etanercept, adalimumab and certolizumab pegol product samples after exposure to freezing temperature conditions similar to storage conditions previously observed in patients’ homes.MethodsTNF-α inhibitors in their original primary and secondary packaging were exposed to 32 freeze-thaw cycles (−10°C for 120min/5°C for 60 min) or continuous low storage temperature (−20°C for 96 h) before thawing at 2–8°C. Non-stressed products were used as controls. The products were analyzed by high pressure size exclusion chromatography (HP-SEC), dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), micro-flow imaging (MFI) and second derivative ultraviolet (UV) spectroscopy.ResultsTen out of twenty-one stressed product samples (47.6%) showed increased particle numbers in the submicron and micron size range when compared to controls. For each product, DLS, MFI and NTA detected an increase in particle level in at least one stressed syringe (both continuous freezing and freeze-thaw), whereas HP-SEC and UV spectroscopy showed no differences between stressed and non-stressed products.ConclusionTNF-α inhibitors are relatively resistant to freezing temperatures similar to storage conditions previously observed in patients’ homes. However, almost half of the stressed product samples showed formation of particles in the submicron and micron size range.

PurposeTo investigate the potential of two flow imaging microscopy (FIM) techniques (Micro-Flow Imaging (MFI) and FlowCAM) to determine total cell concentration and cell viability.MethodsB-lineage acute lymphoblastic leukemia (B-ALL) cells of 2 different donors were exposed to ambient conditions. Samples were taken at different days and measured with MFI, FlowCAM, hemocytometry and automated cell counting. Dead and live cells from a fresh B-ALL cell suspension were fractionated by flow cytometry in order to derive software filters based on morphological parameters of separate cell populations with MFI and FlowCAM. The filter sets were used to assess cell viability in the measured samples.ResultsAll techniques gave fairly similar cell concentration values over the whole incubation period. MFI showed to be superior with respect to precision, whereas FlowCAM provided particle images with a higher resolution. Moreover, both FIM methods were able to provide similar results for cell viability as the conventional methods (hemocytometry and automated cell counting).ConclusionFIM-based methods may be advantageous over conventional cell methods for determining total cell concentration and cell viability, as FIM measures much larger sample volumes, does not require labeling, is less laborious and provides images of individual cells.Electronic supplementary materialThe online version of this article (10.1007/s11095-018-2422-5) contains supplementary material, which is available to authorized users.

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Determining to what extent biophysical characteristics of aggregates affect immunogenicity of therapeutic interferon beta-1b. Three recombinant human interferon beta-1b (rhIFNβ-1b) samples with different levels of aggregates generated by copper oxidation, thermal stress, or left untreated, as well as Avonex(®) drug substance and Betaferon(®) drug product, were injected intraperitoneally in nontransgenic and interferon beta transgenic FVB/N mice 5 times per week for 3 weeks. Antibodies against interferon beta were measured using enzyme-linked immunosorbent assay. UV and fluorescence spectroscopy, dynamic light scattering, size exclusion chromatography, reversed-phase high-performance liquid chromatography (RP-HPLC), fluid imaging microscopy, and resonant mass measurement, as well as sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting, were used to characterize and quantitate aggregates in the 3 rhIFNβ preparations, to correlate biophysical characteristics with immunogenicity. In immune-tolerant interferon beta transgenic FVB/N mice, Betaferon drug product showed the highest immunogenicity, while Avonex drug substance showed the lowest level of immunogenicity. Of the 3 forms of rhIFNβ-1b, copper-oxidized rhIFNβ-1b showed lower immunogenicity than thermally stressed rhIFNβ-1b, despite containing larger aggregates. Both copper-oxidized rhIFNβ-1b and thermally stressed rhIFNβ-1b exhibited changes in protein structure as shown using fluorescence spectroscopy and RP-HPLC. Nontransgenic, nonimmune-tolerant FVB/N mice generated high antibody titers against all interferon beta samples tested. The level of immunogenicity and the breaking of tolerance in FVB/N transgenic mice are not only related to the level of aggregation but also depend on the size and structure of the aggregates.

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