Redox-Sensitive Poly(lactic- co -glycolic acid) Nanoparticles of Palbociclib: Development, Ultrasound/Photoacoustic Imaging, and Smart Breast Cancer Therapy.

Breast cancer is one of the leading causes of mortality in women globally. The efficacy of breast cancer treatments, notably chemotherapy, is hampered by inadequate localized delivery of anticancer agents to the tumor site, resulting in compromised efficacy and increased systemic toxicity. In this study, we have developed redox-sensitive poly(lactic- co -glycolic acid) (PLGA) nanoparticles for the smart delivery of palbociclib (PLB) to breast cancer. The particle size of formulated PLB@PLGA-NPs (nonredox-sensitive) and RS-PLB@PLGA-NPs (redox-sensitive) NPs were 187.1 ± 1.8 nm and 193.7 ± 1.5 nm, respectively. The zeta potentials of nonredox-sensitive and redox-sensitive NPs were +24.99 ± 2.67 mV and +9.095 ± 1.87 mV, respectively. The developed NPs were characterized for morphological and various physicochemical parameters such as SEM, TEM, XRD, DSC, TGA, XPS, etc. The % entrapment efficiency of PLB@PLGA-NPs and RS-PLB@PLGA-NPs was found to be 85.48 ± 1.29% and 87.72 ± 1.55%, respectively. RS-PLB@PLGA-NPs displayed a rapid drug release at acidic pH and a higher GSH concentration compared to PLB@PLGA-NPs. The cytotoxicity assay in MCF-7 cells suggested that PLB@PLGA-NPs and RS-PLB@PLGA-NPs were 5.24-fold and 14.53-fold higher cytotoxic compared to the free PLB, respectively. Further, the cellular uptake study demonstrated that redox-sensitive NPs had significantly higher cellular uptake compared to nonredox-sensitive NPs and free Coumarin 6 dye. Additionally, AO/EtBr assay and reactive oxygen species analysis confirmed the superior activity of RS-PLB@PLGA-NPs over PLB@PLGA-NPs and free PLB. In vivo anticancer activity in dimethyl-benz(a)anthracene-induced breast cancer rats depicted that RS-PLB@PLGA-NPs was highly effective in reducing the tumor size, hypoxic tumor, and tumor vascularity compared to PLB@PLGA-NPs and free PLB. Further, hemocompatibility study reveals that the developed NPs were nonhemolytic to human blood. Moreover, an in vivo histopathology study confirmed that both nanoparticles were safe and nontoxic to the vital organs.