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Abstract
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Dual-responsive nanogels were prepared by
polymerization of itaconic acid (IA) and copolymerization
with methacrylic acid (MA) in aqueous solution of
hydroxypropyl cellulose (HPC) and cross-linking with
N, N′-methylenebisacrylamide (MBAm) through an easy
and green process. FTIR spectroscopy, TEM, AFM,
DLS and zeta potential studies confirmed the semiinterpenetrating
(semi-IPN) polymer network structure
of nanogels. The LCST of HPC was increased to a
higher temperature than HPC’s intrinsic LCST, while
the presence of the MA comonomer improved the hydrophobicity
of the copolymer and reduced LCST to
about body temperature and suppressed the excessive
nanogel aggregation. It was found that the concentration
of reactants impacted the process of nanogel formation.
Additionally, an increasing of cross-linker concentration
led to a reduced size of HPC nanogels. Besides, the
diameter of nanogels was changed with the temperature
and pH. TEM and AFM photographs of copolymer
nanogels illustrated that the nanoparticles with small diameters
(<100 nm) were prepared. With loading the
doxorubicin into the copolymer nanogels, the particle
size became larger (about 150 nm) and due to the electrostatic
interaction of the cationic drug with anionic
particles, the zeta potential was increased. Drug release
processes were followed at pH = 5.0 and 7.4 and with
37- and 41-°C temperatures, respectively. The maximum
in-vitro release studies of drug-loaded nanogels, which
is 91% for the pH 5.0 buffer solution at 41 °C, demonstrated
the temperature- and pH-sensitivity of prepared
copolymer nanogels.
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