Alkaline earth‐driven structural evolution and dissolution behavior of Cu‐doped zinc polyphosphate antibacterial glasses

Due to the dissolution‐controlled release of Cu 2 ⁺/Zn 2 ⁺ ions that inactivate bacterial proteins, Cu‐doped zinc metaphosphate glasses demonstrate broad‐spectrum antibacterial activity. However, the role of alkaline earth oxides (AE) governing dissolution behavior and antibacterial efficacy of Cu‐doped zinc phosphate glasses is insufficiently understood. Hence, this study used the traditional melt‐quenching method to synthesize glasses with molar compositions of 45P 2 O 5 –45ZnO–10AE (AE = MgO, CaO, SrO, or BaO) and 2 mol% CuO doping. As the ionic field strength decreased from Mg 2 ⁺ to Ba 2 ⁺, the phosphorus–oxygen network was depolymerized, accompanied by improved water resistance and decreased antibacterial activity in 2 h. The improved water resistance could be attributed to the increased crosslink provided by the introduction of AE and the improved structural stability of Zn–O coordination, as examined via EXAFS analysis, which decreased the release of Cu 2 ⁺/Zn 2 ⁺ ions. Compared with the uniform dissolution behavior for other glasses, the BaO‐containing glass exhibited a selective dissolution behavior and anomalously higher water resistance within 73 days of water immersion. As observed by FE‐SEM, this phenomenon was accompanied by the formation of a thin and dense layer on the glass surface, which has rarely been reported for soluble phosphate glasses.