Schiff-base reaction induced selective sensing of trace dopamine based on a Pt41Rh59 alloy/ZIF-90 nanocomposite

Zeolitic imidazole frameworks (ZIFs) are a new class of functional porous materials with attractive characters, such as gas storage, selective separation, catalysis, and drug delivery. We report herein using nanoscale ZIF-90 crystals with free aldehyde group of imidazole-2-carboxaldehyde (ICA) ligand for the selective electrochemical detection of dopamine. The averaged adsorption enthalpy ΔH (i.e., isosteric heat) of ZIF-90 to dopamine is estimated as 72 kJ mol^-1 according to grand canonical Monte Carlo (GCMC) simulation. With further modification of a Pt₄₁Rh₅₉ alloy nanocatalyst, the electrochemical sensing performances towards dopamine are improved. The synergetic effect generated by a Pt₄₁Rh₅₉/ZIF-90 nanocomposite endows it a low detection limit of 1 nM and good specificity. The different anti-interference mechanisms to coexisting redox active species and amino analogues are also included in this work. The strategy demonstrated here may be extended to tune metal nodes as well as ligands of ZIFs crystals and further regulating their functionalities for different target molecules identification.