The single-chain mechanics of biomacromolecules have been studied by AFM-based single-molecule force spectroscopy.[1-2] In general,we find that all the biomacromolecules,including DNA,protein and cellulose,show an environment-dependent single-chain mechanics.The force-extension(f-e)curves of dsDNA and proteins obtained in organic solvents show pure elastic behavior,indicating that the biomacromolecules are denatured in the non-aqueous environment.This result reveals that the aqueous environment is crucial to the native structure of biomacromolecules.