Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.
Department of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung 20224, Taiwan.
J Colloid Interface Sci. 2019 Apr 1;541:75-85. doi: 10.1016/j.jcis.2019.01.061. Epub 2019 Jan 16.
Nanomaterials possessing enzyme-like activity have been extensively studied owing to their high stability and tunable catalytic properties. In this work, a simple method has been developed for the synthesis of porous manganese oxide/manganese ferrite (MnO/MnFeO) nanopopcorns (MFNPs) in neutral media. The MFNPs exhibit dual enzymatic activities towards selective oxidation of ketoses followed by HO-induced decline of its catalytic activity. MFNPs, with MnFeO as the core material and an outer layer rich in MnO, were synthesized from ammonium iron(III) citrate and potassium permanganate at 70 °C for 12 h followed by annealing at 300 °C for 6 h. The nanozyme, MFNPs, exhibited oxidase-like activity, which was proved by the oxidation of amplex red (AR) in the presence of dissolved oxygen in the solution, to form fluorescent resorufin. The activity of MFNPs is highly suppressed by HO as a result of its induced dissolution of MnO. In addition, MFNPs having catalytic activity towards the selective oxidation of ketoses (e.g., fructose) followed by the formation of HO. The as-formed HO diminished the catalytic activity of MFNPs for the AR oxidation to form fluorescent resorufin. Upon increasing fructose concentration, the fluorescence of resorufin decreases. Since the MFNPs do not show catalytic activity towards aldose sugars, such as glucose, sucrose, and mannose, the AR/MFNPs probe has high selectivity and sensitivity for detection of fructose with a limit of detection of 32 μM. Our study shows its great potential for quantitation of fructose in honey samples.
纳米材料具有类似酶的活性，由于其高稳定性和可调催化特性，受到了广泛的研究。在这项工作中，开发了一种在中性介质中合成多孔氧化锰/锰铁氧化物（MnO/MnFeO）纳米爆米花（MFNPs）的简单方法。MFNPs 对酮糖的选择性氧化表现出双重酶活性，随后 HO 诱导其催化活性下降。MFNPs 以 MnFeO 为核材料，外层富含 MnO，由柠檬酸铁(III)和高锰酸钾在 70°C 下反应 12 小时，然后在 300°C 下退火 6 小时合成。纳米酶 MFNPs 表现出氧化酶样活性，这是通过在溶液中溶解氧存在的情况下，将安普乐红（AR）氧化形成荧光 Resorufin 来证明的。由于 MnO 的诱导溶解，HO 高度抑制了 MFNPs 的活性。此外，MFNPs 对酮糖（如果糖）的选择性氧化具有催化活性，随后形成 HO。形成的 HO 降低了 MFNPs 对 AR 氧化形成荧光 Resorufin 的催化活性。随着果糖浓度的增加，Resorufin 的荧光强度降低。由于 MFNPs 对醛糖（如葡萄糖、蔗糖和甘露糖）没有催化活性，因此 AR/MFNPs 探针对果糖具有高选择性和灵敏度，检测限为 32µM。我们的研究表明，它在蜂蜜样品中定量检测果糖方面具有很大的潜力。
