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.