Manganese Superoxide Dismutase Coordinating to Fe(II) and Cu(II): Efficient Hydroxyl Radical Generation for Degradation of Contaminants and Antibacterial Application

Manganese superoxide dismutase (SOD) catalyzes the decomposition of hydrogen peroxide (H 2 O 2 ) to generate hydroxyl radicals (•OH). In this study, SOD was encapsulated via coordination with Cu(II), Fe(II), and phosphate in phosphate-buffered saline (PBS) to form a hybrid material denoted as SOD@Cu&Fe&PO 4 . Our study demonstrates that SOD and the coordinated Cu(II)/Fe(II) ions exert a synergistic catalytic effect on •OH generation during H 2 O 2 decomposition. This synergistic behavior stems from the dynamic interplay between the production and consumption of superoxide anion radicals (O 2 •− ). Specifically, O 2 •− is generated as an intermediate in the reactions of coordinated Cu(II) and Fe(II) with H 2 O 2 . The in situ generated O 2 •− is subsequently utilized by encapsulated SOD, which in turn reduces Mn 3 + at the enzyme's active site to Mn 2 + . A continuous supply of O 2 •− to SOD accelerates the Mn 3 + /Mn 2 + redox cycle at its active center. Concurrently, the timely removal of O 2 •− from the Cu(II)/Fe(II)–H 2 O 2 reaction system eliminates the potential inhibition of O 2 •− accumulation, thereby promoting the Fe(III)/Fe(II) and Cu(II)/Cu(I) redox cycles. As a result, SOD@Cu&Fe&PO 4 affords a significantly enhanced •OH generation capacity. Moreover, this hybrid material exhibits enhanced contaminant degradation efficiency and potent antibacterial activity against multidrug-resistant Escherichia coli (MDR E. coli ) and methicillin-resistant Staphylococcus aureus (MRSA). Graphical O 2 •− is generated as an intermediate in the reactions of coordinated Cu(II) and Fe(II) with H 2 O 2 . The in situ generated O 2 •− is subsequently utilized by encapsulated SOD, which in turn reduces Mn 3 + at the enzyme's active site to Mn 2 + . A continuous supply of O 2 •− to SOD accelerates the Mn 3 + /Mn 2 + redox cycle at its active center.