Phage-augmented casein nanocarriers for targeted bioimaging and enhanced combinatorial therapy of triple-negative breast cancer

Cancer is a complex disease, and its development depends on multiple factors, so even after treatment with conventional modalities controlling (inhibiting or accelerating) one of the few factors would not be efficient in cancer mitigation, and the side effects with it are inevitable. One of the major side effects is damaged immune systems, rendering patients with increased chances of microbial infections. Candidiasis is the most common infection seen in surface cancers such as breast cancer. Clotrimazole (Cm) is a well-known antifungal drug, and recently it has been reported to exhibit anticancer activity against breast cancer. As combinatorial therapy has been proven to be highly effective in treating diseases, clotrimazole along with IR780 was encapsulated into phage (Φ)-modified casein nanocarriers (ΦCIRCm NCs). Then, their antifungal activity against <i>Candida albicans</i> was evaluated using spot assay, calcofluor white, and FDA/PI staining. In comparison to casein NCs (CIRCm NCs) the ΦCIRCm NCs showed significantly higher antifungal activity as the presence of phage significantly increased the encapsulation and photothermal transduction efficiency of IR780. Then, for targeted bioimaging and therapy, these NCs were further modified by GSH conjugation. During the conjugation step the presence of phage significantly prevented the loss of IR780 from the NCs. These NCs were evaluated for their theranostic efficiency using 4T1 cells and various <i>in vitro</i> assays. The GSH conjugated NCs (ΦCIRCm-G NCs) displayed significantly higher theranostic efficiency in 2D and 3D cell cultures compared to the control and treatment groups and induced cellular apoptosis by generating ROS and mitochondrial damage eventually causing cell death. Then, the specific targetability and therapeutic efficiency of NCs in the 4T1 breast cancer model were evaluated. The ΦCIRCm-G NCs were specifically accumulated in tumors when compared to ΦCIRCm NCs. Further the <i>in vivo</i> results of ΦCIRCm NCs also displayed significant antitumor efficiency and without causing any damage to the healthy tissues. The targeted NCs will provide new avenues to enhance the theranostic efficacy of various combinatorial therapeutic approaches for treating cancer and its associated health risks with minimal or no side effects.