Association of Calcium Phosphate and Fibroblast Growth Factor‐2: a Dynamic Light Scattering Study

Abstract

The size distributions of fibroblast growth factor-2 (FGF-2) in aqueous solutions with neutral pH were investigated with a dynamic light scattering technique. We found that the FGF-2 was distributed in dimer or trimer form at concentrations of 0.1-1.0 mg . mL(-1). An aggregate with a hydrodynamic radius of approximately 90 nm coexisted with this and its proportion increased with a decrease in concentration. At lower concentrations (less than 0.10 mg . mL(-1)) FGF-2 aggregates with an average radius of 80-100 nm were dominant and were stable for more than a day. These FGF-2 solutions were mixed with calcium phosphate solutions to produce a sub-micron sized compound of FGF-2 and hydroxyapatite, which could be used as a biological implant that possessed a pharmacological function for bone formation. By utilizing a transformation from amorphous calcium phosphate to hydroxyapatite, FGF-2 was effectively incorporated into polycrystals of hydroxyapatite.SEM photograph of a mixture of hydroxyapatite and FGF-2.

Controlling the Release of Small, Bioactive Proteins via Dual Mechanisms with Therapeutic Potential

“…The difference in the FGF-2 release profiles for hydrogels in reducing and non-reducing conditions clearly demonstrates that the release of low molecular weight proteins can be tuned by controlling hydrogel degradation. In addition, the electrostatic heparin-protein interaction prevents free diffusion of FGF-2 from the hydrogels after the initial burst release (hydrodynamic radius of FGF-2 = 2.8 nm, [29] estimated mesh size = ~8 nm). Indeed, Kizilel and coworkers reported rapid release of bovine serum albumin (BSA, hydrodynamic radius = 3.56 nm) and glucagon-like peptide (GLP-1, hydrodynamic radius = 1.3 nm) from similar PEG hydrogels.…”

Multilayer Films Assembled from Naturally-Derived Materials for Controlled Protein Release

“…At 60 bilayers the film is 534 nm, which is considerably thinner than the 3.3 µm for analogous lysozyme-based tetralayers. The weight (16.3 kDa) and hydrodynamic diameter (~5.6 nm 62 ) of bFGF is close to that of lysozyme; however, since only nanogram levels are needed to elicit biological response (ED 50 ~ 1–4 ng/mL), we used a considerably diluted protein solution (50 ug/mL) during assembly that results in less material deposited per tetralayer. Beyond the initial slow growth period (> 20 tetralayers), we found 10.7 nm/tetralayer deposited, which is roughly 6.5-fold less than the lysozyme-based tetralayer films.…”

Recent research on pseudobiological hydroxyapatite crystal growth and phase transition mechanisms

“…Specifically, if a protein that interacts little with calcium phosphate clusters is mixed into a solution containing ACP aggregates, the protein will be incorporated into the clusters as the ACP grows and ultimately, when the HAP is deposited, the protein should be mixed in between the HAP crystal regions. We selected FGF-2, which is a growth factor protein with the ability to activate osteoblasts, and tried using the ACPeHAP phase transition process to produce an HAPeFGF-2 complex [76]. Fig.…”