Nanotechnology for drug delivery systems in colorectal cancer: Recent developments and future prospects

Figure 1 The most popular nano-drug delivery system designs. The ability of nanoparticles (NPs) to specifically recognize their target sites can be improved through the use of targeting ligands, which can be chemically conjugated to the NPs surface. Stimulus-responsive NPs are designed to remain their structural integrity during circulation and to release their payload when exposed to specific external or internal stimuli. A: Passive targeting is NP accumulation inside or beyond the fenestrae of tumor blood vessels; B: Active targeting involves specific binding of target cells with drug delivery systems, mediated by receptor-ligand interactions; C: The triggering factors of stimuli-responsive drug release can originate internally, such as variations in local temperature, pH levels, redox conditions, and enzymatic activity, or externally, including induced heating, ultrasound, magnetic fields, and light exposure.

Figure 2 Emerging potential of nanotherapeutic strategies in colorectal cancer management. Nanotherapeutics in colorectal cancer hold promising role in various fields, including chemotherapy, immunotherapy, radiotherapy, photothermal therapy, targeted delivery using DNA/RNA, and stem cell therapy. CRC: Colorectal cancer; PTT: Photothermal therapy; PDT: Photodynamic therapy.

Figure 3 Nanodrug-mediated synergy of immune checkpoint inhibitors and immunosenescence targeting. Nanocarriers-mediated delivery of immune checkpoint inhibitors and immunosenescence modulators (Toll-like receptor 7/8 agonists) to reprogram the immunosuppressive tumor microenvironment. TCR: T cell receptor; MHCI: Class I major histocompatibility complex; PD-1: Programmed cell death protein 1; PD-L1/2: Programmed death ligand-1/2; TLR7/8: Toll-like receptor 7/8; MyD88: Myeloid differentiation factor 88; IRAK: Interleukin-1 receptor-associated kinase; NF-κB: Nuclear factor kappa B; IRF3/7: Interferon regulatory factor 3/7; DCs: Dendritic cells; Treg: Regulatory T cell; MDSCs: Myeloid-derived suppressor cells; TAM: Tumor-associated macrophage; NK: Natural killer; TME: Tumor microenvironment.