The influence of protein concentration on drop formation and breakup of aqueous solutions of fibrous proteins collagen, fibrinogen, and globular protein thrombin in different concentration regimes is investigated during drop-on-demand (DOD) inkjet bioprinting. The capillary-driven thinning and breakup of dilute (c/c*<1, where c is the concentration and c* is the overlap concentration) collagen, fibrinogen, and thrombin solutions is predominantly resisted by inertial force on the initial onset of necking. The minimum diameter (Df_min(t)) of the necked fluid up to the critical pinch-off time (t_c) scales with time as Df_min(t) ~ (t_c−t)2/3, a characteristic of potential flows. Although the capillary-driven thinning and breakup of semidilute unentangled collagen (1≤c/c*≤4) and fibrinogen (1≤c/c*≤1.3) solutions is predominantly resisted by inertial force on the initial onset of necking, the breakup of droplets is delayed beyond t_c, where the minimum diameter of the necked fluid decreases exponentially with time because of the resistance of elastic force. The resistance of viscous force to the necking of both the dilute and semidilute untangled protein solutions is negligible. Aggregates or subvisible particles (between 1 and 100 microns) constantly disrupt the formation of droplets for the semidilute unentangled protein solutions, even when their inverse Ohnesorge number (Z) is within the printability range of 4≤Z≤14. Although aggregates are present in the dilute protein solutions, they do not disrupt the formation of droplets.

中文翻译：

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浓度对喷墨生物打印过程中胶原蛋白，纤维蛋白原和凝血酶溶液的液滴形成和分解的作用

在按需滴注（DOD）喷墨生物打印过程中，研究了不同浓度下蛋白质浓度对纤维蛋白胶原蛋白，纤维蛋白原和球状凝血酶的液滴形成和破裂的影响。毛细血管驱动的稀化和稀释（c / c * <1，其中c为浓度，c *为重叠浓度）破坏胶原蛋白，纤维蛋白原和凝血酶溶液，在颈缩开始时主要受到惯性力的抵抗。直至临界夹断时间（t _c）的颈缩流体的最小直径（Df _min（t））随时间变化，即Df _min（t）〜（t _c-t）2/3，势能流动的特征。尽管毛细管稀释和半缠结的胶原蛋白（1≤c/ c *≤4）和纤维蛋白原（1≤c/ c *≤1.3）溶液的稀释和破裂在颈缩开始时主要受到惯性力的抵抗，但破裂的液滴延迟超过t _c，因为弹性力的阻力，颈缩流体的最小直径随时间呈指数下降。粘性力对稀和半稀未缠结蛋白质溶液的颈缩的抵抗力可以忽略不计。即使半稀释的未缠结蛋白质溶液的聚集体或亚可见粒子（介于1到100微米之间）也不断破坏液滴的形成，即使其反Ohnesorge数（Z）在4≤Z≤14的可印刷性范围内。尽管聚集体存在于稀蛋白溶液中，但它们不会破坏液滴的形成。