Nanostructured silicate substituted calcium phosphate (NanoSiCaPs) nanoparticles — Efficient calcium phosphate based non-viral gene delivery systems

• Successful demonstration of nanostructured NanoSiCaPs formation
• Demonstration of superior transfection of NanoSiCaPs contrasted to NanoCaPs
• Silicate substitution leads to smaller aggregates of nanoparticle complexes.
• Enhanced dissolution of NanoSiCaPs demonstrated
• Faster NanoSiCaPs dissolution leads to escape of pDNA from lysosomal degradation.

Nanostructured ceramic particles, particularly, nanoparticles of calcium phosphate (CaP) remain an attractive option among the various types of non-viral gene delivery vectors studied because of their safety, biocompatibility, biodegradability, and ease of handling as well as their adsorptive capacity for DNA. We have accordingly developed an enhanced version of nanostructured calcium phosphates (NanoCaPs), by substituting known amounts of silicate for phosphate in the hydroxyapatite (HA) lattice (NanoSiCaPs). Results indicate that in addition to the excellent transfection levels exhibited by un-substituted NanoCaPs alone in vitro, an additional 20–50% increase in transfection is observed for NanoCaPs containing 8.3–50 mol% silicate aptly called NanoSiCaPs, owing to its rapid dissolution properties enabling nanoparticles escaping the lysosomal degradation. However, high silicate substitution (> 50 mol%) resulted in a drastic decline in transfection as the synthesized NanoCaPs deviated far from the characteristic hydroxyapatite phase formed as evidenced by the materials characterization results.

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