The enhanced electrocatalytic performance of nanoscopic CuPdFe heterometallic molecular box encaged cytochrome c

• Published in: Nanoscale Vol. 16; no. 1; pp. 411 - 426
• Main Authors: Nabi, Shazia, Sofi, Feroz Ahmad, Jan, Qounsar, Bhat, Aamir Y, Ingole, Pravin P, Bayati, Maryam, Bhat, Mohsin Ahmad
• Format: Journal Article
• Published: 21.12.2023
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/d3nr03451h

Designing molecular cages for atomic/molecular scale guests is a special art used by material chemists to harvest the virtues of the otherwise vile idea known as "the cage". In recent years, there has been a notable surge in research investigations focused on the exploration and utilization of the distinct advantages offered by this art in the advancement of efficient and stable bio-electrocatalysts. This usually is achieved through encapsulation of biologically accessible redox proteins within specifically designed molecular cages and matrices. Herein, we present the first successful method for encaging cytochrome c (Cyt-c), a clinically significant enzyme system, inside coordination-driven self-assembled Cu 6 Pd 12 Fe 12 heterometallic hexagonal molecular boxes (Cu-HMHMB), in order to create a Cyt-c@Cu-HMHMB composite. 1 H NMR, FTIR, and UV-Vis spectroscopy, ICP-MS, TGA and voltammetric investigations carried out on the so-crafted Cyt-c@Cu-HMHMB bio-inorganic composite imply that the presented strategy ensures encaging of Cyt-c in a catalytically active, electrochemically stable and redox-accessible state inside the Cu-HMHMB. Cyt-c@Cu-HMHMB is demonstrated to exhibit excellent stability and electrocatalytic activity toward very selective, sensitive electrochemical sensing of nitrite exhibiting a limit of detection as low as 32 nanomolar and a sensitivity of 7.28 μA μM −1 cm −2 . Importantly, Cyt-c@Cu-HMHMB is demonstrated to exhibit an excellent electrocatalytic performance toward the 4 pathway oxygen reduction reaction (ORR) with an onset potential of 0.322 V ( vs. RHE) and a Tafel slope of 266 mV dec −1 . Our findings demonstrate that Cu-HMHMB is an excellent matrix for Cyt-c encapsulation. We anticipate that the entrapment-based technique described here will be applicable to other enzyme systems and Cyt-c for various electrochemical and other applications. Privileged to be Encaged: Encaging Cytochrome c into nanoscopic Cu 6 Pd 12 Fe 12 heterometallic molecular boxes significantly enhances its electrochemical stability and electrocatalytic performance toward nitrite ion sensing and Oxygen Reduction Reaction.