## 1 Introduction  
Gigaporous microspheres have unique advantages in bioprocess, especially in enzyme immobilization and the purification of biomolecules with large molecular weight and complex structures. Compared to the conventional agarose particles used in bioseparation with pore sizes of 10-30 nm [1, 2], gigaporous microspheres have pore sizes up to 100-500 nm [3, 4, 5, 6]. When biomolecules such as PEG-protein, viruses, and VLPs (virus-like particles), whose sizes that are 20 nm or larger are purified [7, 8], bigger pores lead to good separation, including higher product bioactivity, a faster separation rate, and higher dynamic loading capacity [9, 10, 11, 12, 13]. As the carrier materials used for the immobilization of enzymes, the immobilized lipase in gigaporous microspheres also shows much higher specific activity, thermal stability, and storage stability. At present, multiple methods are developed to prepare gigaporous polymer materials, such as the high internal phase emulsion method [3, 14, 15], microfluidic [16], the piling of small particles [17], electrospraying [18], and the double emulsification method [19, 20]. However, there are some unfavorable characteristics of the products prepared by these methods, such as low specific surface area and mechanical strength. In order to resolve these disadvantages, a new method named the surfactant reverse micelles swelling method has been put forward [4, 5]. This method can prepare polymer microspheres with controllable pore sizes of 100-500 nm and favorable mechanical strength; the yield of this method was up to 95% and is feasible for mass production. The pore-forming mechanism of this method is as follows. A high concentration of surfactant in oil phase assembles into reverse micelles; and, when the oil phase with micelles mixes with the water phase, the reverse micelles in oil droplets absorb water spontaneously and turn into water channels through the droplet. After polymerization, the water channels become through-holes [21]. By adjusting the surfactant concentration, the diameter of pores can be regulated. However, a new problem appeared in the preparation process. Some particles aggregated weakly. The aggregation can be easily dispersed at about 0.01 MPa pressure, so we did not think this was a big question at first. However, when the pilot test was done, and the production of gigaporous microspheres reached kilogram grade, great effort, such as ultrasonic dispersion or grind, had to be made to re-disperse the aggregate. Could we avoid the occurrence of these aggregations during the preparation process? Common solutions are adding stabilizer in the continuous phase or increasing the rotation speed of emulsion [22; 23]. However, in this system, a high concentration of stabilizer polyvinyl alcohol (PVA) (3%) had been added to the water phase, the viscosity of the water phase was very high. If much more of the stabilizer is added to the water, it is hard to clean the products because of the thick water phase [21]. Moreover, the increase in rotation speed would only have a slight influence to the aggregations of microspheres in this system, and also lead to the changing of the particle size. Thus, a new method to solve this problem based on the formational mechanism of gigapores was put forward in this study. Generally, the stabilizer adsorbs onto the interface of water and oil [21; 23; 24]. However, in the reverse micelles swelling process, gigapores made the water in them connected to the external continuous aqueous phase; at this region, the interface disappears and the stabilizer cannot adsorb there. During the polymerization process, the particles will impact each other inevitably. Without protection of the stabilizer, the particles will easily adhere to each other. If the boundary can be rebuilt, the stabilizer can adsorb onto the interface, and the aggregation may be weakened and even disappear [23]. So rebuilding the boundary is a feasible means of reducing the aggregate.