**Figure 1.**

*Various carrier-based polymeric drug delivery systems including polymeric nanoparticle (a), polymeric micelles (b), metallic nanoparticles (c), dendrimer (d), quantum dot (e), liposome (f), solid lipid nanoparticles (g), nanostructure lipid nanoparticle (h), carbon nanotube (i), antibody-drug conjugate (j), exosome (k). Polymeric nanoparticles are particles within the size range from 1 to 1000 nm and can be loaded with active drugs entrapped within or adsorbed on the surface. Polymeric micelles are nanoscopic core or shell structures formed by amphiphilic block copolymers. Metallic nanoparticles are submicron-scale entities fabricated by reduction using synthetic or green materials. Dendrimers are a class of synthetic polymers with a structure of repeatedly branching chains, typically forming spherical macromolecules. A quantum dot is a nanoscale particle of semiconducting materials that can be embedded in cells or organisms for various experimental purposes, such as labeling proteins. A liposome is a spherical vesicle having at least one lipid bilayer that can carry drugs to deliver at the targeted site within the body. Solid lipid nanoparticles or lipid nanostructure carriers are nanoparticles composed of lipids. Carbon nanotubes are tubes made of carbon with diameters typically measured in nanometers. An antibody-drug conjugate is a class of biopharmaceutical drugs designed as a targeted therapy for treating cancer. Whereas, exosomes are a class of cell-derived extracellular vesicles of endosomal origin, and are typically 30–150 nm in diameter.*
