Antigen-binding fragments (Fabs) are becoming increasingly prevalent as an alternative to full-length monoclonal antibodies. In this work, the digestion of a mixture of different human antibodies isotypes was optimized in terms of different parameters, including the concentration of papain and cysteine, and the digestion time. The recovery of the Fab fragments was subsequently evaluated by designing four different downstream purification schemes, where the use of affinity chromatography (protein A and L) was the most efficient to isolate the Fab fragments after IgG digestion.

A rapid screening of optimal conditions for the binding of pure Fab fragments to four non-affinity chromatography resins was then performed using micro-columns fabricated in a PDMS microfluidic device. The goal of these studies was to screen and evaluate the performance of two cation exchange (carboxymethyl and heparin) and two multimodal (Capto MMC and phenyl boronate) ligands for the capture of Fabs under a wide range of pH (5–9) and conductivity (up to 8 mS/cm) conditions. Multimodal resins showed the best results in binding Fab fragments, particularly at pH 5, well below the range of isoelectric points of the target Fab molecules. In addition, these resins demonstrated to have a salt-tolerant behaviour, meaning that the binding of Fab fragments was not significantly impacted when the conductivity of the adsorption buffer was increased to near-physiological conditions (8 mS/cm).

抗原结合片段（Fabs）作为全长单克隆抗体的替代物正变得越来越普遍。在这项工作中，根据不同参数（包括木瓜蛋白酶和半胱氨酸的浓度以及消化时间）对不同人类抗体同种型混合物的消化进行了优化。随后通过设计四种不同的下游纯化方案评估Fab片段的回收率，其中在IgG消化后，亲和层析（蛋白A和L）是最有效的分离Fab片段的方法。

然后使用在PDMS微流控设备中制造的微柱，对纯Fab片段与四种非亲和层析树脂结合的最佳条件进行了快速筛选。这些研究的目的是筛选和评估两种阳离子交换（羧甲基和肝素）和两种多峰（Capto MMC和苯基硼酸酯）配体的性能，以在宽pH（5-9）和电导率范围内捕获Fab （最高8 mS / cm）条件。多峰树脂在结合Fab片段方面表现出最好的结果，尤其是在pH 5时，远低于目标Fab分子的等电点范围。此外，这些树脂被证明具有耐盐性能，