Two methods for quantifying DNA extracted from poly(lactide-co-glycolide) microspheres

Area of Science:

• Biomaterials Science
• Analytical Chemistry
• Pharmaceutical Sciences

Background:

• Poly(lactide-co-glycolide) (PLG) microparticles are used for DNA delivery.
• Accurate quantification of encapsulated DNA is crucial for assessing drug delivery systems.
• UV spectroscopy and PicoGreen fluorometry are common methods for DNA quantification.

Purpose of the Study:

• To evaluate the utility and limitations of UV spectroscopy and PicoGreen dye for quantifying DNA in PLG microparticles.
• To optimize DNA extraction from PLG microspheres for accurate analysis.
• To assess factors affecting DNA quantification during in vitro release studies.

Main Methods:

• Comparison of DNA quantification using UV spectroscopy and PicoGreen fluorometry.
• Development of a biphasic solvent system for DNA extraction from PLG microspheres.
• Analysis of DNA encapsulation efficiency and in vitro DNA release.

Main Results:

• PicoGreen demonstrated higher sensitivity (12 pg/ml) than UV spectroscopy (0.5 μg/ml) for DNA detection.
• Assay conditions for reproducible DNA extraction from PLG microspheres were established.
• Residual poly(vinyl alcohol) and DNA isoforms (linear, nicked, supercoiled) were found to influence PicoGreen/DNA fluorescence.

Conclusions:

• Both UV spectroscopy and PicoGreen fluorometry have limitations for quantifying DNA in PLG microparticles, necessitating careful method selection.
• Optimized extraction protocols and consideration of interfering substances are vital for accurate DNA quantification in microparticle-based delivery systems.
• Understanding these limitations is essential for reliable assessment of encapsulation efficiency and in vitro DNA release profiles.