Nanostructured Calcium Phosphates for Non-Viral Gene Delivery:
Nanostructured calcium phosphate (NanoCaPs) particles are biocompatible and non-toxic bioceramics widely studied owing to their structural and compositional similarity to the mineralized tissue architecture of native bone. They are therefore considered as an ideal choice for non-viral gene delivery applications in bone tissue engineering. We have developed NanoCaPs in a controlled fashion under physiological conditions of temperature, pH and pressure demonstrating excellent binding and condensation of plasmid DNA. The initial transfection results have also shown excellent repeatability and efficiency matchin traditional non-viral gene delivery lipid and polymer systems. However, NanoCaPs are typically characterized by stability issues leading to variable transfection, short shelf life due to particle aggregation, and difficulties associated with endosomal escape. The objectives of this project were therefore crafted to develop strategies to circumvent, if not eliminate, some of the limitations that have previously stymied the success of NanoCaPs as a non-viral gene delivery vector for bone tissue engineering applications. A modified version of NanoCaPs containing critical concentration of silicate ions substitutions were synthesized, aptly called NanoSiCaPs. Fundamental understanding of the influence of silicate ion substitutions in the NanoCaPs lattice structure was conducted using various materials characterization techniques. In-vitro transfection results indicated, a two-fold increase in transfection levels exhibited by NanoSiCaPs, owing to their enhanced dissolution kinetics and ability to limit particle aggregation. Subsequently, different strategies were also developed to achieve scaffold mediated gene delivery via generation of plasmid DNA bound to NanoSiCaPs (NanoSiCaPs complexes, NC). For examples, it was demonstrated that the Ti-polyelectrolyte-NC assemblies contribute to surface mediated gene transfection, without eliciting any cytotoxicity. Additional studies with novel stabilizing agents added to induce particle size stability and shelf life following lyophilization were also conducted and the results are indeed very promising.
Steps involved in fabrication of
Ti-polyelectrolyte NanoSiCaPs assembly (Adopted from Materials Today Communications 16 (2018) 169–173).
1. MATERIALS SCIENCE AND ENGINEERING C 69, 486–495 (2016).
2. MATERIALS TODAY COMMUNICATIONS 16, 169–173 (2018).
3. MATERIALS SCIENCE AND ENGINEERING B 177(3), p. 289-302 (2012).