title: Motion-Based pH Sensing Based on the Cartridge-Case-like Micromotor.
abstract: In this paper, we report a novel cartridge-case-like micromotor. The micromotor, which is fabricated by the template synthesis method, consists of a gelatin shell with platinum nanoparticles decorating its inner surface. Intriguingly, the resulting cartridge-case-like structure exhibits a pH-dependent "open and close" feature, which originates from the pH responsiveness of the gelatin material. On the basis of the catalytic activity of the platinum nanoparticle inside the gelatin shell, the resulting cartridge-case-like structure is capable of moving autonomously in the aqueous solution containing the hydrogen peroxide fuel. More interestingly, we find out that the micromotor can be utilized as a motion-based pH sensor over the whole pH range. The moving velocity of the micromotor increases monotonically with the increase of pH of the analyte solution. Three different factors are considered to be responsible for the proportional relation between the motion speed and pH of the analyte solution: the peroxidase-like and oxidase-like catalytic behavior of the platinum nanoparticle at low and high pH, the volumetric decomposition of the hydrogen peroxide under the basic condition and the pH-dependent catalytic activity of the platinum nanoparticle caused by the swelling/deswelling behavior of the gelatin material. The current work highlights the impact of the material properties on the motion behavior of a micromotor, thus paving the way toward its application in the motion-based sensing field.
authors.affiliation: Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Collaborative Innovation Center (CIC) of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, People's Republic of China.
authors.forename: Yajun
authors.initials: Y
authors.lastname: Su
authors.affiliation: Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Collaborative Innovation Center (CIC) of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, People's Republic of China.
authors.forename: Ya
authors.initials: Y
authors.lastname: Ge
authors.affiliation: Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Collaborative Innovation Center (CIC) of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, People's Republic of China.
authors.forename: Limei
authors.initials: L
authors.lastname: Liu
authors.affiliation: Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Collaborative Innovation Center (CIC) of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, People's Republic of China.
authors.forename: Lina
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Collaborative Innovation Center (CIC) of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, People's Republic of China.
authors.forename: Mei
authors.initials: M
authors.lastname: Liu
authors.affiliation: Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Collaborative Innovation Center (CIC) of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, People's Republic of China.
authors.forename: Yunyu
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Collaborative Innovation Center (CIC) of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Collaborative Innovation Center (CIC) of Suzhou Nano Science and Technology, Soochow University , Suzhou, Jiangsu 215123, People's Republic of China.
authors.forename: Bin
authors.initials: B
authors.lastname: Dong
mesh_terms: D005780:Gelatin / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry*; D009038:Motion; D010984:Platinum / Q000737:chemistry*
chemical_list: D010984:Platinum; D005780:Gelatin; D006861:Hydrogen Peroxide
keywords: autonomous movement; hydrogen peroxide; micromotor; motion-based sensing; self-propelling