Quercetin loaded folate targeted plasmonic silver nanoparticles for light activated chemo-photothermal therapy of DMBA induced breast cancer in Sprague Dawley rats

Currently, the paucity of free drugs in conventional chemotherapy for breast-cancer curbs the desired therapeutic efficiency, often aggravating systemic toxicity. Quercetin (QRC) is a potential chemotherapeutic bio-flavonoid that is associated with poor hydrophilicity. In contrast to spherical silver nanoparticles (AgNPs), anisotropic AgNPs exhibit prominent plasmonic tunability in the near infrared (NIR) region allowing deep tissue penetration and endowing them with the ability to act as photothermal transducers as well. In this study, we optimized a simple and novel method for synthesizing folate-receptor-targeted-plasmonic silver-nanoparticles (QRC-FA-AgNPs) to serve as an efficient nanoscopic carrier system for breast cancer-cell targeted delivery of QRC and to induce photothermal therapy. A one-pot chemical synthesis method was followed for synthesizing the QRC-FA-AgNPs by finely tailoring the hydrogen bond between the reductant and stabilizer. Detailed characterization through UV-visible, near infrared (UV-vis-NIR) spectroscopy, Fourier transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and energy-dispersive X-ray spectroscopy (EDX), along with particle-size, zeta-potential analysis, drug-loading and release capacity and stability studies were also performed. In vitro targeted cellular uptake, viability studies, chemo-photothermal efficacy, induction of apoptosis and the reactive oxygen species (ROS) generating potential were studied in the MDA-MB-231 cell-line and in vivo evaluation of the chemo-photothermal efficacy of QRC-FA-AgNPs was performed using a 7,12-dimethylbenz(a)anthracene (DMBA)-induced breast-carcinogenesis model in Sprague Dawley rats. Unlike conventional AgNPs, these novel pentagonal QRC-FA-AgNPs (<50 nm) manifested a robust plasmon tunability in the NIR (>800 nm) region. Detailed in vitro and in vivo studies revealed their active role in improving breast-cancer conditions by allowing controlled and targeted discharge of QRC at the tumor site, along with evoking hyperthermia under NIR laser irradiation that induced selective ablation of cancer cells. Following successful cellular internalization, the photothermal efficacy of QRC-FA-AgNPs supplemented their chemotherapeutic potency, allowing apoptosis and restraining the tumor growth. This current study highlighted the augmented efficacy of plasmonic QRC-FA-AgNPs in comparison to free quercetin, thus the development of a potential nanocarrier based on the pleiotropic function of plasmonic AgNPs may provide an efficient combined chemo-photothermal based strategy for the assassination of breast-cancer cells.