Calcium phosphate nanoparticles

Calcium phosphate (CaP) has been utilized as an efficient gene vector for nearly 40 years and siRNA carriers for recent years. Due to their homology to bone and teeth, CaPs have non-toxic nature and exhibit biocompatibility, biodegradability, and lack of immune stimulation. However, one of their major limitations is the untunable growth of the CaP crystal reducing the transfection efficiency (Habraken, Habibovic, Epple, & Bohner, 2016). To address this problem, Pittella et al . (Pittella et al., 2011) prepared a hybrid nanoparticle system to deliver siRNA to pancreatic cancer cells (PANC-1). This hybrid system is made of charge conversional polymer (CCP) as siRNA vehicle, and CaP as the block copolymer of PEG. In this system, CaP constitutes a stable core for siRNA and PEG–CCP encapsulation. The non-toxic synthesized PEG–CCP exerts strong membrane destabilization and rapid escape of siRNA. The incorporation of PEG-block siRNA into CaP leads to a size-controllable hybrid nanoparticle and facilitates the cellular uptake. Encapsulated siRNA (CaP-siRNA with PEG-block polymer nanocarrier) showed high knockdown of VEGF in PANC-1 cells compared with naked siRNA.