3.4 Application performance of MTCFs@SIP@CBMA
3.4.1 Adsorption kinetics
Under the premise that the initial concentration of BSA was 0.1 mg/mL, the relationship between the adsorption capacity of MTCFs@SIP@CBMA and MTCFs@NIP@CBMA on BSA over time was measured. As shown in Figure 6, the adsorption process was obviously divided into four stages. At 0-30 min, the adsorption capacity of MTCFs@SIP@CBMA on BSA gradually increased with time. The reason was described as that BSA first bound to the imprinted sites on the surface of the fibers relying on electrostatic attraction, hydrogen bonding and hydrophobic interaction. As time gone on, the binding amount increased. At 30-60 min, the adsorption capacity remained unchanged, indicating that the imprinted sites on MTCFs@SIP@CBMA surface reached saturation. The saturated adsorption capacity for BSA was 395.26 mg/g. However, the osmotic pressure difference between the inside and outside of the tube would drive BSA to migrate into the cavity through the pores on the tube wall. The balance of adsorption capacity suggested that the adsorbed BSA still occupied the imprinting sites. At 30-100 min, the adsorption capacity increased again with time, and the adsorption capacity was significantly higher than the equilibrium adsorption capacity. This illustrated that the BSA on the surface of MTCFs@SIP@CBMA disengaged from the imprinting sites and diffused into the cavity. At this time, the remaining BSA in the solution again adsorbed to the imprinting sites on the surface. After 100 min, the BSA migrating into the cavity migrated out of the fiber port and migrated outward at a rate greater than the adsorption rate, so the adsorption amount decreased with time. The above adsorption results well confirmed the self-driven adsorption performance of MTCFs@SIP@CBMA. For MTCFs@NIP@CBMA, owing to the lack of imprinting sites matching with BSA on its surface and the grafting of anti-protein adsorption chain segments, the adsorption capacity was significantly lower than MTCFs@SIP@CBMA (only 57.42 mg/g). Simultaneously, because MTCFs@NIP@CBMA had no imprinted cavity connected to the carrier fibers and the coated PDA and CBMA polymers were compact, the adsorption process of MTCFs@NIP@CBMA did not exhibit self-driven adsorption performance.