Electrochemical system encapsulated by nanoscale liposomes enabling on-demand triggering of electroless deposition at selected areas

• Main Authors: Zhan, Jing, Lin, Ming, Arai, Satoshi, Yang, Wan Wei, Sou, Keitaro, Sato, Hirotaka
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Article
• Language: English
• Published: 2021
• Subjects: Engineering::Mechanical engineering; Electroless Deposition; Thermosensitive Liposome
• Online Access: https://hdl.handle.net/10356/154646
• Institution: Nanyang Technological University

This study proposed and demonstrated an application for nanoscale thermosensitive liposomes: encapsulating chemicals (reducing agents or metal ions) to physically separate reducing agents from metal ions and temporarily prevent spontaneous reduction of the metal ion (i.e., deposition of the metal or electroless deposition). With such an electrochemical system encapsulated by nanoscale liposomes, we can trigger electroless deposition at areas of interest by heating on demand, which enables metallization at selected surface areas. We used 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) as the lipid to synthesize thermosensitive liposomes (gel-to-liquid-crystalline phase transition temperature at 40 °C) encapsulating hypophosphite (the reducing agent),and mixed it with a PdCl2 solution. The liposomes stably held the reducing agent for 160 days as long as it was stored in a fridge at 3 °C. When the temperature exceeded the phase transition temperature, the reducing agent was released from the liposomes and induced Pd deposition. This electroless deposition system encapsulated by thermosensitive liposomes was applied to metalize selected spots of the internal surface of a glass capillary tube: the mixture was injected into the tube and several spots were heated externally, and Pd metal was deposited at the spots. Furthermore, we succeeded in microscopically visualizing a single liposome thermally releasing the reducing agent and inducing metal deposition locally. Overall, on-demand triggering of electroless deposition can be accomplished by applying thermosensitive liposomes was demonstrated to be feasible. This new electrochemical system using nanoscale liposomes can be used to achieve metal coatings on various surfaces of interest.