Design and Development of Theranostic Nanomedicines - Nanotechnology for Biomedical Imaging and Diagnostics - page 443

be developed with targeting molecules on the surface, such as the folate-coated
multifunctional plga/pFpl nanoparticle system shown in Figure 15.9. Theranostic
polymers can be developed through various synthetic methods (direct polymeriza-
tion, self-assembly, nanoprecipitation, emulsification/precipitation, etc.), which have
been summarized in recent reviews [160, 168-170]. polymeric nanoparticle formu-
lation is best described through a recent nanoparticle example [171]. in this study,
Tpgs-functionalized plga particles were prepared for controlled release of pTX
with a uniform size of 130-150 nm and a drug entrapment efficiency of 80%. The
particles were synthesized by a modified inverse-phase nanoprecipitation method
where the aqueous phase containing Tpgs was slowly added into the water miscible
organic phase. With the slow diffusion of the organic solvent into the aqueous solution,
plga was precipitated to form nanoparticles and the Tpgs coated as the monolayer
around the plga polymeric core simultaneously. simultaneous self-assembly and
precipitation leads to small particle size with high uniformity and high drug loading.
summary of most common polymeric nanoparticle synthesis approaches is shown in
Figure 15.10, and for detailed discussion, the reader is referred to reference [172].
an early approach to develop theranostic polymers involves incorporation of
photosensitizers into polymeric nanoparticles. For example, McCarthy et al . reported
poly(lactic-co-glycolic acid) nanoparticles that encapsulate the photosensitizer
meso-tetraphenylporpholactol [173]. Due to self-quenching, encapsulated meso-
tetraphenylporpholactol did not produce significant fluorescence signal or cytotoxic
singlet oxygen. however, when photosensitizer was released upon cellular uptake of
the polymeric nanoparticles, considerable fluorescence signals and phototoxicity
were recovered. In vivo phototherapy study in a prostate cancer mouse model showed
complete eradication of tumors.
a major limitation of photosensitizer-incorporated polymeric nanoparticles is low
tissue penetration of light, as most photosensitizers absorb in the visible region. To
address this issue, nir fluorescence dyes and chemotherapy agents were introduced

Polymeric nanoparticles
synthesis

Polymerization Polymeric dispersion

Emulsion polymerization

Supercritical
uid technology
Microuidics
technology

Controlled (live)
radical polymerization

Solvent
evaporation

Salting out
and dialysis

Microemulsions

Nanoprecipitation

Surfactant-free
emulsions

Mini (nano)
emulsions

figure 15.10 a brief summary of common methods for polymeric nanoparticle synthesis
used in drug delivery and imaging.