| STUDY |
Enzyme triggers slow desorption of polymer films
Incorporating an enzyme into a biopolymer-synthetic polymer multilayer assembly and devising a way to activate the enzyme is a potential approach to developing better controlled-release materials, according to a report by professor Mitsuru Akashi and coworkers at Kagoshima University, in Japan [Angew. Chem. Int. Ed., 42, 1115 (2003)]. The researchers use electrostatic attraction to build up 16 alternating layers of anionic DNA and cationic poly(diallyldimethylammonium chloride) (PDDA). The crucial layer is the 17th and final one, which is deoxyribonuclease I (DNase I) that is electrostatically deposited onto PDDA. When the multilayer assembly is placed into a solution containing Ca2+ and Mg2+, the DNase I is activated and the electrostatic charge holding the enzyme is neutralized, which releases it to start snipping away the ion-activated DNA. The DNA fragments dissolve and form complexes with PDDA, and eventually the multiple layers fall apart one by one. The desorption rate depends on the ion concentration and the amount of enzyme used. This system could be optimized for controlled release of a drug or other material under varying conditions, the researchers suggest
|