Micelles are good devices for use as controlled
drug delivery systems because they exhibit the ability to
protect the encapsulated substance from the routes of
degradation until they reach the site of action. The present
work assesses loading kinetics of a hydrophobic drug,
pilocarpine, in polymeric micellar nanoparticles (NPs) and
its pH-dependent release in hydrophilic environments. The
trigger pH stimulus, pH 5.5, was the value encountered in
damaged tissues in solid tumors. The new nanoparticles were
prepared from an amphiphilic block copolymer, [(HEMA19%-
DMA31%)-(FMA5%-DEA45%)]. For the present research, three
systems were validated, two of them with cross-linked cores
and the other without chemical stabilization. A comparison of
their loading kinetics and release profiles is discussed, with the support of additional data obtained by scanning electron
microscopy and dynamic light scattering. The drug was loaded into the NPs within the first minutes; the load was dependent on
the degree of cross-linking. All of the systems experienced a boost in drug release at acidic pH, ranging from 50 to 80% within the
first 48 h. NPs with the highest degree (20%) of core cross-linking delivered the highest percentage of drug at fixed times. The
studied systems exhibited fine-tuned sustained release features, which may provide a continuous delivery of the drug at specific
acidic locations, thereby diminishing side effects and increasing therapeutic rates. Hence, the studied NPs proved to behave as
smart controlled drug delivery systems capable of responding to changes in pH.Ministerio de Economía y Competitividad de España-MAT2016-77345-C3-2-PJunta de Andalucía-P12-FQM-155
