Sodium dodecyl sulfate-capillary gel electrophoresis with native fluorescence detection for analysis of therapeutic proteins.

A 280 nm light-emitting diode (LED) was used as the excitation source for native fluorescence detection (NFD) of proteins in capillary electrophoresis. The NFD scheme was evaluated in sodium dodecyl sulfate-capillary gel electrophoresis (SDS-CGE) for monoclonal antibody (mAb) characterization. Utilizing a technique by which we filtered the LED emission through a 280 nm bandpass filter, we were able to increase overall concentration sensitivity of SDS-CGE-NFD ~2.

Native fluorescence detection with a laser driven light source for protein analysis in capillary electrophoresis.

While ultraviolet light (UV) absorbance detection is the most widely used detection mode in capillary electrophoresis (CE), it can yield poor concentration sensitivity and has tendencies to exhibit baseline fluctuations. In order to overcome these challenges, alternative detection strategies, including the use of dedicated wavelength lasers, have been applied, resulting in enhancements of concentration sensitivity as well as decreased baseline disturbance. In this work, using a laser driven light source for excitation, we reported a native fluorescence detection (NFD) scheme for use in a commercial CE platform, PA 800 Plus Pharmaceutical Analysis System, for protein analysis.

Fluorescent pseudorotaxanes of a quinodicarbocyanine dye with gamma cyclodextrin.

Spectrophotometric titration of buffered solutions of gamma cyclodextrin (γCD) and 1,1'-diethyl,2,2'-dicarbocyanine (DDI) demonstrates extension of the known 1:2 host:guest complex to form a previously unreported 2:2 complex near the γCD solubility limit. Though DDI is predominantly hosted as a non-fluorescent H-aggregate, both complexes exist in respective equilibria with two secondary complexes hosting unaggregated DDI as 1:1 and 2:1 complexes. The 2:1 complex exhibits significant fluorescence emission, with a quantum yield six times that of DDI in organic solvents, but ten times lower than that of an analogous indodicarbocyanine.

Relation of molecular structure to Franck-Condon bands in the visible-light absorption spectra of symmetric cationic cyanine dyes.

A Franck-Condon (FC) model is used to study the solution-phase absorbance spectra of a series of seven symmetric cyanine dyes having between 22 and 77 atoms. Electronic transition energies were obtained from routine visible-light absorbance and fluorescence emission spectra. Harmonic normal modes were computed using density functional theory (DFT) and a polarizable continuum solvent model (PCM), with frequencies corrected using measured mid-infrared spectra.