The adsorption of bovine serum albumin (BSA) protein is important for protein research but remains a great challenge. Here, the hydrothermal method and calcination in a hydrogen-argon mixed atmosphere were used to obtain ordered mono-crystalline magnetic Fe 3 O 4 nanorings with controllable size and uniform structure, which were applied to the adsorption of BSA protein. The results showed that the magnetic Fe 3 O 4 nanorings prepared have the advantages of good crystallinity, controllable morphology, and excellent magnetic response. The Fe 3 O 4 nanorings had an outer diameter of ~160–180 nm, inner diameter of ~80–110 nm, and height of 70 to ~110 nm. The amount of BSA adsorbed by magnetic Fe 3 O 4 nanorings increased with increasing protein concentration; when the concentration of BSA was ~2.75 mg·mL -1 the adsorption amount approached saturation. When the pH value of the solution was ~5, the Fe 3 O 4 nanorings absorption of BSA was greatest. With increasing adsorption time, the amount adsorbed increased gradually. Adsorption equilibrium was reached after 3 h. According to the formula, the saturated adsorption capacity of BSA per gram of magnetic Fe 3 O 4 nanorings was 325.2 mg.
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Revealing the adsorption behavior of proteins on amphiphilic polymers is an interesting study. For the first time, the adsorption behavior of bovine serum albumin (BSA) protein on the surface of polyethylene glycol polystyrene (PEG-PS) amphiphilic polymer membrane is developed by molecular dynamics (MD) simulations and experiments. We found that PEG-PS has the ability to resist BSA protein adsorption. The adsorption of BSA on its surface undergoes a process of "rotation-preadsorption-desorption-final adsorption". After adsorption, the helical structure of BSA underwent "tight-loose-unwinding" changes. The transition from PEG chain helical structure to free coil structure is a key factor leading to the adsorption and desorption of BSA. Furthermore, the hydrophobic force of PS is the main driving force for BSA adsorption. These studies can inspire the design of amphiphilic materials to realize protein antifouling or transportation materials.
Chronic kidney disease caused by functional impairment of glomerular endothelial cells (GECs) is one of the etiologies of hemodialysis treatment. As a critical component of the hemodialysis process, hemodialysis membranes having been suffering from intricated modification methods. In order to solve a series of problems caused by blood incompatibility, usually triggered by rough surfaces, an anticoagulant coating with a similar physical structure and physiological properties to GECs was prepared on the polyethersulfone (PES) membrane. The smooth glomerular endothelium-like coating was obtained by a hydrated layer formed by tannic acid (TA) and α-lipoic acid (α-LA). We explored two possible reaction mechanisms of TA and α-LA, which were characterized and discussed by ATR-FTIR and XPS. Besides, the hydrophilic and negatively charged coating has filtration and anticoagulant properties similar to those of GECs. The results show that the modified membranes have appreciable hydrophilicity (the water contact angle is 29.7°) as well as high urea removal rate (96.5%) and BSA protein retention (99.7%). In addition, the modified membranes show favorable hemocompatibility and free radical scavenging ability. The reduction of platelet adhesion number is reduced by 98.7% and PRT is prolonged to 297 s. DPPH and ABTS radical scavenging capacity reach 1.18 and 0.89 μmol/cm 2 , respectively. In this work, a surface coating mimicking GECs was fabricated for the potential candidates of new hemodialysis membranes, which will significantly enhance the dialysis efficiency and alleviate the coagulation.
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