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Charge variation is one of the most important heterogeneities during monoclonal antibody (mAb) manufacturing and this study presents insights into the generation of acidic charge variants during cell culture processes. Since acidic variants generate both intracellularly and extracellularly, main charge fraction collected by weak cation exchange chromatography (WCX) was incubated in harvested cell supernatant (HCS) to simulate and investigate the extracellular process firstly. It is found that the main fraction was degraded rapidly into acidic variants rather than basic variants extracellularly, and the degradation sites were located in both Fab and Fc fragments indicated by papain digestion. Besides, certain process parameters were investigated as their potential roles in the extracellular process. As a result, media composition showed significant influence on degradation while culture time point did not, suggesting that the extracellular process was a spontaneous process without enzyme catalysis. Additionally, kinetics study reveals that the extracellular process was a pseudo first-order reaction. The E value (21.59 kcal/mol) estimated from the Arrhenius equation suggests that the extracellular degradation might be mainly attributed to asparagine deamidation. Furthermore, we established an acidic variants generation model, indicating that the extracellular process plays a dominant role in modulating the final acidic variant level. This study provides better understanding for controlling product heterogeneity in mAb manufacturing. [ABSTRACT FROM AUTHOR]

In recent years, photothermal materials that can convert light into heat energy have attracted extensive attention. In this work, we report a simple and effective approach to construct a self-cleaning photothermal superamphiphobic fabric. Dopamine (DA) can self-polymerize into polydopamine (PDA) and adhere to the surface of cotton fabric as a secondary reaction platform. Then, SiO 2 nanoparticles were in situ grown on the PDA@fabric surface by the sol-gel method. The PDA clusters can not only provide good photothermal conversion performance but also be integrated with SiO 2 to create micro-nano rough structures. Finally, the surface of SiO 2 was modified by the long chain of fluorosilane to decrease the fabric surface energy, resulting in superamphiphobicity. The contact angles of water, ethylene glycol, and pump oil on the modified fabric surface could reach 161.1, 158.1, and 142.2°, respectively, making the fabric resistant to contamination by water, common beverages, and oil. Due to the adhesion of the PDA layer, the strong binding force between the fabric and SiO 2 particles enabled the modified fabric to withstand various chemical and mechanical attacks, showing excellent mechanical robustness and harsh environmental stability. More importantly, the surface temperature of the modified fabric could be increased from 19.6 to 37.0 °C, which is close to the human body temperature, under the irradiation of simulated sunlight ( I = 15 A, 300 s). The photothermal superamphiphobic fabrics with self-cleaning properties show great promise in the photothermal conversion field.