A method of making a poly-N-acetylglucosamine nanoparticle/nucleic acid composition comprises (a) adding a base to poly-N-acetylglucosamine to deacetylate 60% to 70% of the poly-N-acetylglucosamine (b) adding a mineral acid or organic acid to a form a deacetylated poly-N-acetylglucosamine ammonium salt derivative (c) adding a buffer to facilitate dilution and (d) adding a nucleic acid, thereby making a poly-N-acetylglucosamine nanoparticle/nucleic acid composition. The mineral acid or organic acid is lactic acid, citric acid, succinic acid, gluconic acid, glucoronic acid, malic acid, pyruvic acid, tartaric acid, tartronic acid or fumaric acid. The buffer in step (c) is sodium acetate-acetic buffer or ammonium acetatate-acetic acid buffer.
