Poly(ethylene glycol) methyl ether acrylate (PEGMEA) is copolymerized with 2-(ferrocenecarboxylate ethyl) methacrylate (EMA-Fc) and 4-(propoxy urethane ethyl acrylate) azobenzene (EMA-Azob), respectively. The nanoparticles can be obtained via the single-chain folding of these amphiphilic copolymers with hydrophilic poly(ethylene glycol) (PEG) side chains and hydrophobic ferrocene (or azobenzene) pendant groups in dilute aqueous solution via intramolecular hydrophobic interaction. After the addition of cyclodextrin, the inclusion complex can be formed between cyclodextrin and ferrocene (or azobenzene) pendant groups, which makes the amphiphilic copolymers hydrophilic and triggers the chain unfolding of the nanoparticles in aqueous system. Such kind of process has potential application in the fields of drug delivery systems and their controlled release, sensors, controllable catalysis, mimicry of biomacromolecules, as well as other fields. (C) 2018 Elsevier Ltd. All rights reserved.