Advancing multiproduct resin reuse for development and clinical manufacturing of an antibody-based therapeutic.

Chromatography resins used for purifying biopharmaceuticals are generally dedicated to a single product. For clinical manufacturing, this can result in resin being used only for a fraction of its potential lifetime. Extending the use of resins to multiple products can significantly reduce resin waste and cost.

Fluorescence correlation spectroscopic examination of insulin and insulin-like growth factor 1 binding to live cells.

We used fluorescence correlation spectroscopy to examine the binding of insulin, insulin-like growth factor 1 (IGF1) and anti-receptor antibodies to insulin receptors (IR) and IGF1 receptors (IGF1R) on individual 2H3 rat basophilic leukemia cells. Experiments revealed two distinct classes of insulin binding sites with K(D) of 0.11 nM and 75 nM, respectively.

Cy3 in AOT reverse micelles II. Probing intermicellar interactions using fluorescence correlation spectroscopy.

Cyanine-3 (Cy3) fluorescent dye molecules confined in sodium di-2-ethylhexyl sulfosuccinate (AOT) reverse micelles were examined using dynamic light scattering and fluorescence correlation spectroscopy to probe the kinetics of Cy3 dye and reverse micelle aggregation. This study explored a range of reverse micelle sizes, defined as w(0) = [H(2)O]/[AOT], in which the occupation number ranged from one Cy3 molecule per ∼10(5) to ∼10(6) reverse micelles. These measurements reveal that in the smallest reverse micelle, w(0) = 1, the Cy3 molecules aggregate to form H-aggregate dimers, and the Cy3 dimerization is accompanied by the formation of a transient dimer between reverse micelles.

Cy3 in AOT reverse micelles I. Dimer formation revealed through steady-state and time-resolved spectroscopy.

Cyanine-3 (Cy3) fluorescent dye molecules confined in sodium di-2-ethylhexyl sulfosuccinate (AOT) reverse micelles were examined using steady-state absorption and emission as well as time-resolved fluorescence spectroscopy to understand the effect of confinement on the spectroscopic properties of the dye. This study explored a wide range of reverse micelle sizes, with hydrodynamic radii ranging from ∼1.7 to ∼5 nm.

Probing the ionic atmosphere of single-stranded DNA using continuous flow capillary electrophoresis and fluorescence correlation spectroscopy.

Two-beam fluorescence cross-correlation spectroscopy coupled with continuous flow capillary electrophoresis (2bFCCS-CFCE) was used to study the relationship between diffusion and effective charge of a fluorescently labeled 40-base polythymine single-stranded DNA (ssDNA) as a function of Mg2+ concentration. Cross-correlation analysis of the fluorescence monitored from two spatially offset microscopic detection volumes revealed the diffusion and electrophoretic migration of ssDNA at a range of Mg2+ concentrations and electric field strengths. The effective charge of the ssDNA could then be determined using simple calculations.