Herein, we have developed nanohybrids (nHs) to remotely
activate
a therapeutic enzyme for its use in Directed Enzyme Prodrug Therapy
(DEPT). The coencapsulation of magnetic nanoparticles (MNPs) with
horseradish peroxidase (HRP) using biomimetic silica as an entrapment
matrix was optimized to obtain nanosized hybrids (∼150 nm)
for remote activation of the therapeutic enzyme. HRP converts indole-3-acetic
acid (3IAA) into peroxylated radicals, whereas MNPs respond to alternating
magnetic fields (AMFs) becoming local hotspots. The AMF application
triggered an increase in the bioconversion rate of HRP matching the
activity displayed at the optimal temperature of the nHs (Topt= 50 °C) without altering the temperature
of the reaction media. This showed that enzyme nanoactuation is possible
with MNPs even if they are not covalently bound. After an extensive
physicochemical/magnetic characterization, the spatial location of
each component of the nH was deciphered, and an insulating role of
the silica matrix was suggested as critical for introducing remote
control over HRP.In vitroassays, using a human
pancreatic cancer cell line (MIA PaCa-2), showed that only upon exposure
to AMF and in the presence of the prodrug, the enzyme-loaded nHs triggered
cell death. Moreover,in vivoexperiments showed
higher reductions in the tumor volume growth in those animals treated
with nHs in the presence of 3IAA when exposed to AMF. Thus, this work
demonstrates the feasibility of developing a spatiotemporally controlled
DEPT strategy to overcome unwanted off-target effects.