纳米酶，具有酶模拟活性和优异的稳定性，引起了广泛的关注。然而,一些固有的缺点，包括分散性差，低选择性,过氧化物酶样活性不足，仍然限制了它的进一步发展。因此,进行了纳米酶和天然酶的创新生物缀合。在氧化石墨烯（GO）的存在下，首先通过溶剂热法合成组氨酸磁性纳米颗粒（H-Fe3O4）。GO负载的H-Fe3O4（GO@H-Fe3O4）表现出优异的分散性和生物相容性，因为GO是载体，并且由于组氨酸的引入而具有出色的过氧化物酶样活性。此外，GO@H-Fe3O4的过氧化物酶样活性的机制是·OH的产生。选择尿酸氧化酶（UAO）作为模型天然酶，并以亲水性聚（乙二醇）作为接头与GO@H-Fe3O4共价连接。UAO能特异性催化尿酸(UA)氧化生成H2O2,新产生的H2O2氧化了无色的3,3'，GO@H-Fe3O4催化下的5,5'-四甲基联苯胺（TMB）到蓝色ox-TMB。基于上述级联反应，GO@H-Fe3O4连接的UAO（GHFU）和GO@H-Fe3O4连接的ChOx（GHFC）用于检测血清样品中的UA和牛奶中的胆固醇（CS），分别。基于GHFU的方法对UA具有宽检测范围（5-800μM）和低检测限（1.5μM），基于GHFC的方法对CS具有较宽的检测范围（4-400μM）和较低的检测限（1.13μM）。这些结果表明，所提出的策略在临床检测和食品安全领域具有巨大的潜力。
Nanozyme, with enzyme-mimicking activity and excellent stability, has attracted extensive attention. However, some inherent disadvantages, including poor dispersion, low selectivity, and insufficient peroxidase-like activity, still limit its further development. Therefore, an innovative bioconjugation of a nanozyme and natural enzyme was conducted. In the presence of graphene oxide (GO), histidine magnetic nanoparticles (H-Fe3O4) were first synthesized by a solvothermal method. The GO-supported H-Fe3O4 (GO@H-Fe3O4) exhibited superior dispersity and biocompatibility because GO was the carrier and possessed outstanding peroxidase-like activity because of the introduction of histidine. Furthermore, the mechanism of the peroxidase-like activity of GO@H-Fe3O4 was the generation of •OH. Uric acid oxidase (UAO) was selected as the model natural enzyme and covalently linked to GO@H-Fe3O4 with hydrophilic poly(ethylene glycol) as a linker. UAO could specifically catalyze the oxidation of uric acid (UA) to generate H2O2, and subsequently, the newly produced H2O2 oxidized the colorless 3,3\',5,5\'-tetramethylbenzidine (TMB) to blue ox-TMB under the catalysis of GO@H-Fe3O4. Based on the above cascade reaction, the GO@H-Fe3O4-linked UAO (GHFU) and GO@H-Fe3O4-linked ChOx (GHFC) were used for the detection of UA in serum samples and cholesterol (CS) in milk, respectively. The method based on GHFU exhibited a wide detection range (5-800 μM) and a low detection limit (1.5 μM) for UA, and the method based on GHFC exhibited a wide detection range (4-400 μM) and a low detection limit (1.13 μM) for CS. These results demonstrated that the proposed strategy had great potential in the field of clinical detection and food safety.
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