Purpose.To evaluate factors that contribute to the stability of DNA deposited on gold particles. Methods.A model plasmid DNA of 5.6 kb and pure gold particles of 2-3 �m were used in this study. Deposition of the DNA plasmid and different levels of excipients on the gold particles is achieved by means of an ethanol precipitation process. Storage stability of these DNA- and excipient-deposited gold particle was evaluated at 40 �C. The level of deposited DNA was monitored by micro UV spectrophotometry and the level of deposited excipients was monitored by RP-HPLC. DNA stability was evaluated by quantitative agarose gel electrophoresis. Results.It was found that DNA remains stable during the preparation process with a minimal loss of supercoil. However, the deposited DNA degrades from supercoil to circular or linear form with time at 40 �C. The deposited levels of certain excipients such as trehalose and EDTA play a positive role in protecting DNA stability. A clear correlation was observed between DNA stability and the level of trehalose and EDTA on the gold particles. Moisture content of gold/DNA formulations also significantly affect the stability of DNA associated with the gold.Conclusions.DNA remains stable during the preparation process. Certain excipients, including sugars and EDTA, inhibit DNA degradation in solid state. The levels of deposited excipients and moisture content are key factors that significantly affect storage stability of DNA on gold particles. Rational design of DNA/gold formulation would help to improve DNA stability.

Particle mediated epidermal delivery of DNA: Stability of DNA on gold particles

239th National Meeting (2010)

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