Experimental and Numerical Determination of Interface Slip Coefficient of Fluid Stream Exiting a Partially Filled Porous Medium Channel

Stacks of parallel plates modeled as a standard fissure-type anisotropic porous medium are filled inside a rectangular channel up to half the cross section height. The interface slip coefficient a for the isothermal laminar incompressible flow exiting this partially filled porous-medium channel is then determined using particle image velocimetry (PIV) experiments and numerical simulations. Required measurements of the Darcy velocity u D on the porous-medium (PM) side, the local velocity u f , and its gradient @u f =@y on the clear-fluid (CF) side are performed across different length scales. The fissure-type porous-medium parameters are systematically varied in the porosity range 0:2 / 0:95 and flow direction permeability 10 À6 < K; m 2 < 10 À9 . From the exit-velocity profile, the empirical slip coefficient a is determined using a generalized relationship. When the measurements across the PM-CF interface are performed across a length scale equal to the representative elemental length (REL) of the porous media considered (i.e., equal to the sum of plate thickness (a) and gap (b)), the determined a value is found to remain invariant

Hydrogel Microsphere Encapsulation Enhances the Flow Properties of Monoclonal Antibody Crystal Formulations

Monoclonal antibodies are therapeutic molecules known for their high specificity and versatility in the treatment of cancer and autoimmune disorders, but dosage forms are typically limited to low concentrations and large fluid volumes due to formulation challenges. Hydrogel microsphere formulations offer a route to quicker, patient-friendly dosing regimens for monoclonal antibodies with high loading and favorable flow properties needed for injection through a narrow syringe needle under moderate applied force. Crystals of an intact monoclonal antibody are prepared as a concentrated suspension (>300 mg mL−1) which is then encapsulated within hydrogel microspheres with diameters as small as 30 µm. The hydrogel microspheres contain up to 56 wt% (dry basis) monoclonal antibody and release within 4 days under in vitro dissolution conditions. The hydrogel microspheres are concentrated into densely packed suspensions containing up to 300 mg mL−1 monoclonal antibody to evaluate their flow. These hydrogel formulations shear-thin and have lower viscosity when compared to both liquid and suspended crystal forms of the monoclonal antibody, demonstrating the potential of hydrogel microsphere encapsulants as a carrier which can mask undesirable flow properties of concentrated antibody therapeutics

SANS from micellar solutions of CTAB and sodium salicylate

SANS from 0.1M solution of CTAB without and with addition of varying concentrations of NaSal has been studied. The measured spectra show that on addition of NaSal two or more of CTAB micelles join together to form a bigger micelle. These micelles disintegrate to smaller ones on heating

Effect of Pegylation on Self-Association of IFN-α2b

Pegylation of therapeutic proteins is an established technology used to enhance the bioavailability of an active pharmaceutical ingredient in the body of patients. While the physiochemical properties of pegylated monomeric proteins have been extensively described, there is still limited information on the characterization of pegylated oligomeric proteins. In this study, we report the characterization of a pegylated interferon alpha2b (PEGIFN-α2b) concentration-dependent oligomerization by a series of orthogonal biochemical and biophysical methods. These methods include sedimentation velocity and sedimentation equilibrium analytical ultracentrifugation, matrix-assisted laser desorption ionization, and size exclusion chromatography of bissulfosuccinimidyl suberate cross-linked PEGIFN. We report here that PEGIFN-α2b self-associates in a concentration-dependent manner into mainly monomers, dimers, and trimers. In the presence of the chemical cross-linker, PEGIFN-α2b is primarily monomeric (57%) at concentration lower than 0.3 mg/mL and contains about equal amount of monomers and dimers (47.0% and 37.7%, respectively), about 15% of trimers, and up to 4% of higher molecular weight species at 0.7 mg/mL and above