The increased cell density and product titer in biomanufacturing have led to greater use of depth filtration as part of the initial clarification of cell culture fluid, either as a stand‐alone unit operation or after centrifugation. Several recent studies have shown that depth filters can also reduce the concentration of smaller impurities like host cell proteins (HCP) and DNA, decreasing the burden on subsequent chromatographic operations. The objective of this study was to evaluate the HCP removal properties of the Pall PDH4 depth filter media, a model depth filter containing diatomaceous earth, cellulose fibers, and a binder. Experiments were performed with both cell culture fluid (CCF) and a series of model proteins with defined pI, molecular weight, and hydrophobicity chosen to match the range of typical HCP. The location of adsorbed (fluorescently labeled) proteins within the depth filters was determined using confocal scanning laser microscopy. Protein binding was greater for proteins that were positively charged and more hydrophobic, consistent with adsorption to the negatively charged diatomaceous earth. The lowest degree of binding was seen with proteins near their pI, which were poorly removed by this filter. These results provide new mechanistic insights into the factors governing the filter capacity and performance characteristics of depth filters containing diatomaceous earth that are widely used in the clarification of CCF.

中文翻译：

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使用含有硅藻土的过滤器进行深度过滤去除宿主细胞蛋白质的有效性。

生物制造中细胞密度和产品滴度的增加导致更多地使用深层过滤作为细胞培养液初始澄清的一部分，无论是作为独立单元操作还是离心后。最近的几项研究表明，深层过滤器还可以降低宿主细胞蛋白 (HCP) 和 DNA 等较小杂质的浓度，从而减轻后续色谱操作的负担。本研究的目的是评估颇尔 PDH4 深层过滤介质（一种包含硅藻土、纤维素纤维和粘合剂的模型深层过滤器）的 HCP 去除性能。使用细胞培养液 (CCF) 和一系列具有确定的 pI、分子量和疏水性的模型蛋白质进行实验，以匹配典型 HCP 的范围。使用共聚焦扫描激光显微镜确定深层过滤器内吸附（荧光标记）蛋白质的位置。对于带正电且疏水性更强的蛋白质，蛋白质结合更大，这与对带负电的硅藻土的吸附一致。在接近 pI 的蛋白质中观察到最低程度的结合，该过滤器很难去除这些蛋白质。这些结果为控制广泛用于澄清 CCF 的含有硅藻土的深层过滤器的过滤能力和性能特征的因素提供了新的机械见解。与对带负电的硅藻土的吸附一致。在接近 pI 的蛋白质中观察到最低程度的结合，该过滤器很难去除这些蛋白质。这些结果为控制广泛用于澄清 CCF 的含有硅藻土的深层过滤器的过滤能力和性能特征的因素提供了新的机械见解。与对带负电的硅藻土的吸附一致。在接近 pI 的蛋白质中观察到最低程度的结合，该过滤器很难去除这些蛋白质。这些结果为控制广泛用于澄清 CCF 的含有硅藻土的深层过滤器的过滤能力和性能特征的因素提供了新的机械见解。