Curcumin
(CU), a diphenolic natural flavonoid, has been
considered
as a next-generation anticancer agent; however, its efficacy is hindered
by poor selectivity and low bioavailability (<3 × 10–8 μM). Nanoformulation becomes a promising strategy for the
target-specific delivery of flavonoid, wherein nanoformulation itself
exhibits multiple therapeutic and diagnostic modalities. Presently,
we have developed CU and Prussian blue nanocube (PBNC)-based nanoformulation
which shows chemo-phototoxicity against triple-negative breast cancer
(TNBC, ca. MDA-MB-231 cell line) but possesses compatibility against
normal HEK-293 cells up to a concentration of ∼42 ± 2.1
μg/mL. We have validated the dual-mode T1–T2 weighted magnetic resonance
imaging (MRI) capability of the nanoformulation having relaxivity
parameters r1 ∼ 6.01 mM–1 s–1 and r2 ∼
15.89 mM–1 s–1 under a clinical
magnetic field of 3 T, higher than relaxivity parameters of commercially
available MRI contrast agents [MAGNEVIST (r1 ∼ 3.1 mM–1 s–1, r2 ∼ 3.7 mM–1 s–1), GADOVIST (r1 ∼
3.2 mM–1 s–1, r2 ∼ 3.9 mM–1 s–1), and PROHANCE (r1 ∼ 2.8 mM–1 s–1, r2 ∼ 3.2 mM–1 s–1 etc.].
Meanwhile, the size dependence of relaxivity parameters is dependent
on crystal inhomogeneity and magnetization. In the therapeutic part,
we have noticed oxidative stress-induced pyroptotic cell death, indexed
by the expression of series of proteins including P2RX7-CASPASE1 and
IL-1β-NLRP3. Smaller-sized particles show better theranostic
activity due to easy internalization. In summary, our study suggests
that PBNC (∼60 nm) is highly beneficial to deliver CU, while
our conceptual study clearly demonstrates the role of size and functionalization
on its theranostic properties.