Osteogenic apatite particles by sol-gel assisted electrospraying

Electrospraying is a promising technique for fabricating ceramic particles at submicron to nano scales. Prior research has shown that this method can produce particles with unique structural and functional properties. However, no prior work had resolved how to control the crystalline phase of apatite particles using electrospraying. It was already known that hydroxyapatite (HA) and calcium-deficient hydroxyapatite (CDHA) are commonly used in bone regeneration. Yet, the influence of particle phase on cell response remained unclear. This gap motivated the current investigation into phase-controlled apatite particles. That uncertainty drove the need to explore how particle characteristics affect osteogenic outcomes. No prior work had examined the internalization of electrosprayed apatite particles by cells. This gap motivated the study of particle-cell interactions and drug release profiles.

The aim of this study was to develop a sol-gel assisted electrospraying method for synthesizing apatite particles with controlled phase composition. The specific problem addressed was the lack of control over particle size and crystalline phase in conventional electrospraying. The motivation was to produce particles with predictable osteogenic properties. The researchers also wanted to assess whether these particles could support cell proliferation and mineralization. Another objective was to evaluate the drug loading and release capabilities of the particles. The study sought to compare electrosprayed apatite with microwave-synthesized apatite. The researchers aimed to determine how particle phase affects gene expression in stem cells. The study also aimed to confirm the biocompatibility of the particles with osteoblast-like cells.

The researchers employed sol-gel assisted electrospraying to synthesize apatite particles. They varied process parameters to control particle size and phase composition. The particles were characterized using scanning electron microscopy and X-ray diffraction. Cell viability was assessed using cytotoxicity assays on HOS cells. Proliferation was measured using cell counting and metabolic activity tests. Alkaline phosphatase activity was quantified as a marker of osteogenic differentiation. Gene expression of osteopontin and osteocalcin was analyzed using real-time PCR. Drug loading and release of tetracycline were evaluated using spectrophotometric methods.

The electrosprayed apatite particles ranged from submicron to nano sizes. Both hydroxyapatite and calcium-deficient hydroxyapatite phases were successfully synthesized. The particles were non-cytotoxic and supported the proliferation of HOS cells. Internalization of particles by cells was confirmed using fluorescence microscopy. Alkaline phosphatase activity increased by 1.5-fold compared to control groups. Collagen and calcium deposition were significantly higher in treated cells. Gene expression of osteopontin and osteocalcin increased by 2.3- and 1.8-fold respectively. Tetracycline loading and release were more efficient in electrosprayed particles than in microwave-synthesized ones.

The sol-gel assisted electrospraying method produced phase-controlled apatite particles with desired properties. The particles supported cell proliferation and mineralization without toxicity. Increased gene expression indicated osteogenic commitment of mesenchymal stem cells. Internalization of particles by cells suggests potential for intracellular drug delivery. The particles outperformed microwave-synthesized apatite in drug loading and release. These findings suggest the method is suitable for biomedical applications requiring controlled particle properties. The authors propose that this approach could be used in bone regeneration and drug delivery systems. The methodology may open avenues for a wide range of biomedical applications.