Key Laboratory of Straw Biology and Utilization, The Ministry of Education, College of Life Science, Jilin Agricultural University, Changchun 130118, People's Republic of China.
Department of Physics, Georgia Southern University, Statesboro, GA 30460, USA.
Int J Nanomedicine. 2020 Jan 15;15:263-273. doi: 10.2147/IJN.S220718. eCollection 2020.
Combined superoxide dismutase (SOD)/catalase mimetics have attracted much attention because of their efficacy against reactive oxygen species-associated diseases; however, their application is often limited owing to their poor stability and the absence of favorable grafting sites. To address this, we developed a new class of SOD/catalase mimetics based on hybrid nanoflowers, which exhibit superior stability and possess the desired grafting sites for drugs and endogenous molecules.
In this work, for the first time, we used polynitroxylated human serum albumin (PNA) to mediate the formation of hybrid copper-based nanoflowers. HO depletion and O evolution assays were first performed to determine the catalase-like activity of the hybrid nanoflowers. Next, the xanthine oxidase/cytochrome c method was used to assay the SOD-like activity of the nanoflowers. Further characteristics of the nanoflowers were evaluated using scanning electron microscopy (SEM), electron paramagnetic resonance (EPR), and Fourier-transform infrared spectroscopy (FTIR). Operational stability was assessed via the reusability assay.
The HO depletion and O evolution assays indicated that PNA-incorporated nanoflowers have genuine catalase-like activity. Kinetic analysis revealed that the reactions of the incorporated nanoflowers with HO not only obey Michaelis-Menton kinetics, but that the nanoflowers also possess a higher affinity for HO than that of native catalase. The FTIR spectra corroborated the presence of PNA in the hybrid nanoflowers, while the EPR spectra confirmed the intermolecular interaction of nitroxides bound to the human serum albumin incorporated into the nanoflowers. The remarkable operational reproducibility of the hybrid nanoflowers in catalase-like and SOD-like reactions was verified across successive batches.
Herein, a comparison of Michaelis constants showed that the hybrid nanoflower, a catalase mimetics, outperforms the native catalase. Acting as a "better-than-nature" enzyme mimetics, the hybrid nanoflower with superior stability and desired ligand grafting sites will find widespread utilization in the medical sciences.
由于过氧化物歧化酶 (SOD)/过氧化氢酶模拟物在对抗与活性氧相关的疾病方面具有疗效，因此受到了广泛关注；然而，由于其稳定性差且缺乏合适的嫁接位点，其应用常常受到限制。为了解决这个问题，我们开发了一类基于杂化纳米花的新型 SOD/过氧化氢酶模拟物，它具有优越的稳定性，并且具有药物和内源性分子所需的嫁接位点。
在这项工作中，我们首次使用多硝基化人血清白蛋白 (PNA) 来介导杂化铜基纳米花的形成。首先进行 HO 耗竭和 O 释放测定，以确定杂化纳米花的过氧化氢酶样活性。接下来，使用黄嘌呤氧化酶/细胞色素 c 法测定纳米花的 SOD 样活性。进一步通过扫描电子显微镜 (SEM)、电子顺磁共振 (EPR) 和傅里叶变换红外光谱 (FTIR) 评估纳米花的特性。通过可重复使用性测定评估操作稳定性。
HO 耗竭和 O 释放测定表明，PNA 掺入的纳米花具有真正的过氧化氢酶样活性。动力学分析表明，掺入的纳米花与 HO 的反应不仅遵循米氏动力学，而且纳米花对 HO 的亲和力高于天然过氧化氢酶。FTIR 光谱证实了 PNA 存在于杂化纳米花中，而 EPR 光谱证实了与掺入纳米花的人血清白蛋白结合的氮氧自由基之间的分子间相互作用。杂化纳米花在过氧化氢酶样和 SOD 样反应中的显著操作重现性在连续批次中得到了验证。
在此，米氏常数的比较表明，作为一种过氧化物歧化酶模拟物，杂化纳米花优于天然过氧化物酶。作为一种“优于天然”的酶模拟物，具有优越稳定性和所需配体嫁接位点的杂化纳米花将在医学科学中得到广泛应用。
