Cacl2 solution

The unretracted and retracted bovine blood clots were utilized in this test. The fresh bovine blood clots were made with a similar process described in our earlier study [41 (link),42 (link)]. Initially, the 2.75 % W/V 10 mL CaCl₂ solution (Fisher Scientific, Fair Lawn, NJ, USA) was blended with the 100 mL fresh bovine blood (Densco Marketing, Inc., Wood stock, IL, USA) in a volume ratio of 10:1. Next, half of the mixed-blood solution was transferred to a 2 mL micro-centrifuge plastic tube batch to form the unretracted clot. The other half of the mixed-blood solution was injected into the 2 mL borosilicate glass pipettes to form the retracted blood clot. Then the unretracted and retracted blood clots were incubated in the water bath (PolyPro Bath, Model RS-PB-100, USA) at 37 °C for three hours. Finally, the blood clots were put in storage in a freezer at ~4 °C for 72 h to two weeks to form clots of different ages. In each thrombolysis test, the clot samples were sliced into the cylinder shape with a length of about 10 ± 2 mm and a diameter of about 3 ± 0.5 mm. The weight of the clot samples was maintained at about 120 ± 12 mg in mass for each test. The prepared clot was finally placed into a venous flow model (Fig.3) for the in-vitro thrombolysis test.