Neither the influence of high shear rates nor the impact of cavitation on protein aggregation is fully understood. The effect of cavitation bubble collapse‐derived hydroxyl radicals on the aggregation behavior of human serum albumin (HSA) was investigated. Radicals were generated by pumping through a micro‐orifice, ultra‐sonication, or chemically by Fenton's reaction. The amount of radicals produced by the two mechanical methods (0.12 and 11.25 nmol/(L min)) was not enough to change the protein integrity. In contrast, Fenton's reaction resulted in 382 nmol/(L min) of radicals, inducing protein aggregation. However, the micro‐orifice promoted the formation of soluble dimeric HSA aggregates. A validated computational fluid dynamic model of the orifice revealed a maximum and average shear rate on the order of 108 s−1 and 1.2 × 106 s−1, respectively. Although these values are among the highest ever reported in the literature, dimer formation did not occur when we used the same flow rate but suppressed cavitation. Therefore, aggregation is most likely caused by the increased surface area due to cavitation‐mediated bubble growth, not by hydroxyl radical release or shear stress as often reported.

中文翻译：

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空化和高剪切应力对 HSA 聚集行为的影响

高剪切速率的影响和空化对蛋白质聚集的影响均未完全了解。研究了空化气泡破裂衍生的羟基自由基对人血清白蛋白（HSA）聚集行为的影响。自由基是通过泵入微孔、超声波或通过芬顿反应化学产生的。两种机械方法 (0.12 和 11.25 nmol/(L min)) 产生的自由基量不足以改变蛋白质的完整性。相比之下，Fenton 反应产生 382 nmol/(L min) 的自由基，诱导蛋白质聚集。然而，微孔促进了可溶性二聚体 HSA 聚集体的形成。经验证的孔口计算流体动力学模型显示最大和平均剪切速率约为 108 s-1 和 1.2 × 106 s-1，分别。虽然这些值是文献中报道的最高值，但当我们使用相同的流速但抑制空化时，并没有发生二聚体形成。因此，聚集很可能是由于空化介导的气泡生长导致表面积增加引起的，而不是经常报道的羟基自由基释放或剪切应力引起的。