Background:
Plasmid DNA has been widely used in vaccination as well as in cell and
gene therapy. It exists in multiple isoforms including supercoiled, nicked or open circular and
linear forms. Regulatory agencies recommend having more than 80% of the supercoiled isoform
for bulk release of plasmid products; thus it should be analyzed accordingly.
Methods and Results:
The traditional analysis method for plasmid DNA is agarose gel electrophoresis.
However, due to time-consuming manual sample loading, visualization, and data analysis, it has
limitations in obtaining consistently quantitative results. In this short communication, we introduce
a fast, sensitive, and robust plasmid analysis method using capillary electrophoresis with laserinduced fluorescence detection (CE-LIF). CE-LIF analysis of the supercoiled isoform and its open
circular counterpart was completed in 20 minutes with excellent sensitivity by using a common
fluorescent groove binding dye. The advantage of the method was demonstrated by the purity
analysis of two large plasmids (7 kb and 10 kb). The fully automated sample loading, separation
and data analysis featured enhanced assay repeatability and ease of quantitation over agarose gelelectrophoresis.
Conclusion:
As a worked example, analysis of plasmid samples treated at
elevated temperature during an accelerated stability test also demonstrated the applicability of CELIF to monitor plasmid degradation.
Simultaneous determination of nitrate and nitrite in human serum has been accomplished using gradient ion chromatography and direct UV detection, with centrifugal ultrafiltration as the only pretreatment. The method has advantages over previous techniques in both ease of use and cost per assay. The sensitivity is adequate for use as a monitor of nitric oxide induced changes in serum nitrate and nitrite levels.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.