The role of colloid particles in the albumin-lanthanides interaction: The study of aggregation mechanisms

Lithium-Modified TiO2 Surface by Anodization for Enhanced Protein Adsorption and Cell Adhesion

Promoting osseointegration is an essential step in improving implant success rates. Lithium has gradually gained popularity for promoting alkaline phosphatase activity and osteogenic gene expression in osteoblasts. The incorporation of lithium into a titanium surface has been reported to change its surface charge, thereby enhancing its biocompatibility. In this study, we applied anodization as a novel approach to immobilizing Li on a titanium surface and evaluated the changes in its surface characteristics. The objective of this study was to determine the effect of Li treatment of titanium on typical proteins, such as albumin, laminin, and fibronectin, in terms of their adsorption level as well as on the attachment of osteoblast cells. Titanium disks were acid-etched by 66 wt % H2SO4 at 120 °C for 90 s and set as the control group. The etched samples were placed in contact with an anode, while a platinum bar served as the counter electrode. Both electrodes were mounted on a custom electrochemical cell filled with 1 M LiCl. The samples were anodized at constant voltages of 1, 3, and 9 V. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) results showed no significant differences in the topography. However, the ζ potentials of the 3 V group were higher than those of the control group at a physiological pH of 7.4. Interestingly, the adsorption level of the extracellular matrix protein was mostly enhanced on the 3 V-anodized surface. The number of attached cells on the Li-anodized surfaces increased. The localization of vinculin at the tips of the stretching cytoplasmic projections was observed more frequently in the osteoblasts on the 3 V-anodized surface. Although the optimal concentration or voltage for Li application should be investigated further, this study suggests that anodization could be an effective method to immobilize lithium ions on a titanium surface and that modifying the surface charge characteristics enables a direct protein-to-material interaction with enhanced biological adhesion.

Development, Optimization, and Pharmacokinetics Study of Bufalin/Nintedanib Co-loaded Modified Albumin Sub-microparticles Fabricated by Coaxial Electrostatic Spray Technology

Coaxial electrostatic spray technology has received extensive attention in fabricating micro/nanoparticles for drug delivery. However, there are few reports on applying this technology in preparing albumin nanoparticles. In this study, the bufalin (BF) and nintedanib (NDNB) co-loaded ursodeoxycholic acid and p-biguanides benzoic acid decorated albumin sub-microparticles (BN-DUB subMPs) were fabricated by coaxial electrostatic spray technology and optimized by central composite design. Five percent of albumin (contained 0.7% polyethylene oxide) solution was selected as the shell solution which ejected through outer axis with the flow rate of 0.07 mm/min, while the core solution which contained by BF and NDNB ethanol solution was ejected through inner axis with the flow rate of 0.05 mm/min. In vitro cell studies revealed that the modified albumin possessed good biocompatibility. What's more, the BN-DUB subMPs enhanced the inhibitory effect on the growth of LLC cells efficiently. The pharmacokinetics study showed that the t_1/2 and AUC_0-t of BN-DUB subMPs increased significantly compared with that of the drug solution, which indicated the improved in vivo stability of modified albumin nanoparticles. Thus, this study provided a novel and simple technical platform for the development of albumin-based drug carriers.

The change of surface charge by lithium ion coating enhances protein adsorption on titanium

Surface charge is one of the essential physicochemical properties of titanium surfaces for extracellular protein adsorption. Titanium surfaces are generally electronegatively charged at physiological pH. Typical cellular adhesive proteins and cell membranes are also negatively charged. Therefore, there are no direct electric interactions between proteins and titanium surfaces at physiological pH. The objective of this study was to determine how different electrical charges on titanium surfaces affect protein adsorption. Commercially pure grade-2 titanium disks, 19 mm in diameter and 1.5 mm in thickness, having acid-etched micro-roughed surfaces, were prepared. Electropositive charge was supplied by soaking in LiOH solution at concentrations of 0.05, 0.1, 0.25, 0.5, and 1.0 M. After LiOH treatment, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were performed. The zeta potential, isoelectric point, and wettability of titanium surfaces were measured. The adsorption levels of proteins, including albumin, laminin, and fibronectin, were evaluated. Osteoblastic cell attachment level was also determined. Incorporation of Li was detected in the oxide layer of titanium without surface morphological modification. The zeta potential was shifted up and the isoelectric point was increased from 3.94 to 5.63 by LiOH treatment. Long-term super-hydrophilicity was also obtained on Li-treated surfaces. The adsorption of albumin and laminin increased with increasing concentration of LiOH treatment solution, whereas fibronectin adsorption was highest upon treatment with 0.25 M. The osteoblastic cell attachment level was shown to be dependent on the amount of fibronectin adsorbed. In conclusion, LiOH treatment enhances biological adhesion on titanium with an increase in surface charge and hydrophilicity. This study suggests that modifying the surface charge provides a direct protein-to-materials interaction and the optimal application of Li should be investigated further.