One-Step
Synthesis of Nanosized and Stable Amino-Functionalized
Calcium Phosphate Particles for DNA Transfection
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Abstract
Calcium phosphate (CaP) is used for
in vitro transfection because
of low toxicity and simple and low cost synthesis. The transfection
results however vary because the precipitation lacks reproducibility
and results in polydispersed, agglomerated particles. Here a reproducible,
one-step procedure for the preparation of amino-modified CaP nanoparticles
(NPs) is described using <i>N</i>-(2-aminoethyl)-3-aminopropyltrimethoxysilane
as modifying and dispersing agent. The aim was to produce homogeneous,
stable CaP NPs, which are loaded with DNA after particle formation.
The refined wet-precipitation method yielded NPs with a narrow size
distribution (∼140 nm) and positive zeta potential at physiological
pH. FTIR and Raman spectroscopy analysis verified the aminosilane
modification. Interestingly two types of CaP crystalline structures,
Brushite and Hydroxyapatite, can be produced depending on the pH and
without hydrothermal treatment. Both CaP crystalline phases were characterized
using X-ray diffraction (XRD), transmission electron microscopy (TEM),
and Brunauer–Emmett–Teller (BET) analysis. Both showed
very low toxicity and enabled reproducible transfection of A549 cells.
The higher surface functionalization density of Brushite NPs led to
superior pDNA condensation capability and higher transfection in lower
NP concentration. The advantages of the improved synthesis are the
achievement of stable, crystalline CaP NPs in higher yield and narrow
distributed size achieved by agglomeration reduction even without
hazardous surfactant