In nature, the chaperonin proteins GroEL encapsulate denatured proteins inside a cylindrical cavity and release the encapsulated proteins by the action of ATP.  We demonstrated that GroEL can also enfold CdS semiconductor nanoparticles, giving them high thermal and chemical stability in aqueous media.  Analogous to the biological function of the chaperonins, the nanoparticles can be readily released from the protein cavities by the action of ATP.

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Chaperonin–mediated Stabilization and ATP–triggered Release of Semiconductor Nanoparticles.

Daisuke Ishii, Kazushi Kinbara, Yasuhiro Ishida, Noriyuki Ishii, Mina Okochi, Masafumi Yohda, and Takuzo Aida

Nature 2003423, 628–632.

Trapping and ATP-Triggered Release of Semiconductor Nanocluster by a Molecular Chaperon