Post-load column wash in Protein A chromatography can effectively improve host cell protein (HCP) clearance. A commonly used wash additive for this purpose is sodium chloride. However, the adequate amount of sodium chloride required for effective HCP clearance is less consistent in literature. In this study we investigated the impact of different amounts of sodium chloride on HCP clearance with five monoclonal antibodies (mAbs). For each mAb, elution pool HCP levels from runs under different wash conditions are compared.
For all five mAbs, the data suggested that 250 mM would be an adequate amount for the salt to largely achieve its HCP reducing effect. The same conclusion is also reached for calcium chloride, a less commonly used but equally effective Protein A wash additive for HCP clearance.

Inactivation of viruses using novel protein A wash buffers

Low pH viral inactivation is typically performed in the eluate pool following the protein A capture step during the manufacturing of monoclonal antibodies and Fc-fusion proteins. However, exposure to low pH has the potential to alter protein quality. To avoid these difficulties, novel wash buffers capable of inactivating viruses while antibodies or Fc-fusion proteins were bound to protein A or mixed mode resins were developed. By equilibrating the column in high salt buffer (2 M ammonium sulfate or 3 M sodium chloride) after loading, the hydrophobic interactions between antibodies and protein A ligands were increased enough to prevent elution at pH 3.
The ammonium sulfate was also found to cause binding of an antibody to a mixed mode cation exchange and a mixed mode anion exchange resin at pH values that caused elution in conventional cation and anion exchange resins (pH 3.5 for Capto Adhere and pH 8.0 for Capto MMC), indicating that retention was due to enhanced hydrophobic interactions. The potential of the 2 M ammonium sulfate pH 3 buffer, a 1 M arginine buffer, and a buffer containing the detergent LDAO to inactivate XMuLV virus when used as protein A wash buffers with a 1 hour contact time were studied. The high salt and detergent containing wash buffers provided about five logs of removal, determined using PCR, and complete combined removal and inactivation >> 6 logs), determined by measuring infectivity. The novel protein A washes could provide more rapid, automated viral inactivation steps with lower pool conductivities.

Maternal plasma or human serum albumin in wash buffer enhances enrichment and ex vivo expansion of human umbilical cord blood CD34+ cells

Umbilical cord blood is a valuable source of haemopoietic stem/progenitor cells (HSC) for transplantation. This study explored the effect of maternal plasma/human serum albumin (HSA) in the purification and culture conditions of CD34+ cells derived from human umbilical cord blood. During CD34+ cell enrichment, including maternal plasma or HSA instead of fetal bovine serum (FBS) in the wash buffer, significantly increased the purity and the fold expansion of CD34+ cells. The increase in fold expansion of CD34+ cells was independent of CD34+ cell purity before expansion. With FBS, the mean fold expansion of CD34+ cells and total nucleated cells on day 7 was 9.7 +/- 5.5 and 39.7 +/- 13.7 respectively.
The use of maternal plasma increased the mean fold expansion of CD34+ cells and total nucleated cells on day 7 to 28.2 +/- 6.7 and 71.5 +/- 15.4 respectively. When HSA was added to wash buffer, the mean fold expansion of CD34+ cells and total nucleated cells were 30.4 +/- 10.5 and 83.5 +/- 24.8 respectively. No statistical significance was found between using HSA and maternal plasma on total cell and CD34+ cell expansion. We propose that HSA in maternal plasma was responsible for the positive effect on CD34+ cell enrichment and expansion.

Enhanced removal of detergent and recovery of enzymatic activity following sodium dodecyl sulfate-polyacrylamide gel electrophoresis: use of casein in gel wash buffer

The inclusion of 1% casein or bovine serum albumin in buffer used to reactivate enzymes subjected to sodium dodecyl sulfate (SDS)-polyacrylamide electrophoresis resulted in accelerated removal of SDS and restoration of nuclease and beta-galactosidase enzyme activities. Nuclease and beta-galactosidase activities which are absent from gels after longer wash procedures are detectable with this technique. Enzyme activity in gels prepared with SDS which contained inhibitory contaminants was partially restored by the casein wash procedure. The threshold of detection of two-dimensionally separated deoxyribonuclease I using the casein wash procedure was 1 picogram.

Development of a cell wash buffer that minimizes nucleic acid loss from Clostridium perfringens 10543 A

Autolytic activity and nucleic loss from Clostridium perfringens 10543 A was demonstrated during successive cell washes in hypotonic TES buffer. Autolysis increased nearly sixfold and nucleic acid loss nearly twofold when 10 mM EDTA was added to 0.3 M Tris-sucrose buffer. Attempts to minimize both autolysis and nucleic acid loss from C. perfringens during routine washing steps were unsuccessful when the effects of sucrose concentration, pH, CaCl2 addition, or wash temperature were examined independently. However, autolytic activity was eliminated and nucleic acid loss reduced to less than 5% when C. perfringens cells were washed at 4 or 25 degrees C in 1.0 M sucrose, 50 mM Tris–HCl, and 25 mM CaCl2 at pH 5.7.

Nano Differential Scanning Fluorimetry-Based Thermal Stability Screening and Optimal Buffer Selection for Immunoglobulin G

Nano differential scanning fluorimetry (nanoDSF) is a high-throughput protein stability screening technique that simultaneously monitors protein unfolding and aggregation properties. The thermal stability of immunoglobulin G (IgG) was investigated in three different buffers (sodium acetate, sodium citrate, and sodium phosphate) ranging from pH 4 to 8. In all three buffers, the midpoint temperature of thermal unfolding (Tm) showed a tendency to increase as the pH increased, but the aggregation propensity was different depending on the buffer species. The best stability against aggregation was obtained in the sodium acetate buffers below pH 4.6. On the other hand, IgG in the sodium citrate buffer had higher aggregation and viscosity than in the sodium acetate buffer at the same pH. Difference of aggregation between acetate and citrate buffers at the same pH could be explained by a protein-protein interaction study, performed with dynamic light scattering, which suggested that intermolecular interaction is attractive in citrate buffer but repulsive in acetate buffer. In conclusion, this study indicates that the sodium acetate buffer at pH 4.6 is suitable for IgG formulation, and the nanoDSF method is a powerful tool for thermal stability screening and optimal buffer selection in antibody formulations.

SnS 2 Nanoparticles and Thin Film for Application as an Adsorbent and Photovoltaic Buffer

Energy consumption and environmental pollution are major issues faced by the world. The present study introduces a single solution using SnS2 for these two major global problems. SnS2 nanoparticles and thin films were explored as an adsorbent to remove organic toxic materials (Rhodamine B (RhB)) from water and an alternative to the toxic cadmium sulfide (CdS) buffer for thin-film solar cells, respectively. Primary characterization tools such as X-ray photoelectron spectroscopy (XPS), Raman, X-ray diffraction (XRD), and UV-Vis-NIR spectroscopy were used to analyze the SnS2 nanoparticles and thin films.


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Borax Buffer 0.00996M

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TT Buffer (Tris-Tricine buffer) Primix powder

| Bio Basic | 1PK, 10L: 91.32 EUR

ADA buffer

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PBS Buffer

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DMS Buffer

| Bio-WORLD | 1 g: 90.31 EUR
At a reaction time of 180 min, 0.4 g/L of SnS2 nanoparticles showed the highest adsorption capacity of 85% for RhB (10 ppm), indicating that SnS2 is an appropriate adsorbent. The fabricated Cu(In,Ga)Se2 (CIGS) device with SnS2 as a buffer showed a conversion efficiency (~5.1%) close to that (~7.5%) of a device fabricated with the conventional CdS buffer, suggesting that SnS2 has potential as an alternative buffer.