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Tumor Discovery Targeted drug delivery systems for the treatment of tumors

Figure 4. Polymeric nanocarriers involved in tumor management.

nanoparticles, solid lipid nanoparticles, dendrimers, and In contrast, smaller particles (below the pore diameter of
inorganic nanoparticles, have been reported for their tumor cells) can easily penetrate tumor cells and exhibit
effectiveness in the treatment of various types of tumors . passive targeting but are swiftly pushed back into the
[39]
Their unique size, shape, and surface architecture allow circulatory system due to the high interstitial pressure
for active targeting (binding to specific cell receptors), within tumor cells . Therefore, optimizing particle size
[42]
passive targeting (enhanced EPR and dysfunctional lymph can enhance intratumor distribution, cell penetration,
vessels), and cell-mediated targeting (stimulated cytokines retention, and, consequently, the effectiveness of
and chemokines). The size of nanoparticles significantly antitumor treatment. Yu et al. have demonstrated an
influences various factors, including circulation time, intelligent, size-tunable approach for proficient antitumor
biodistribution, accumulation, penetration, and cellular action . The size-tunable approach overcomes the
[43]
uptake within tumor cells or tissues. Circulation time limitations associated with nanoparticles, as their sizes
and particle size serve as pivotal determinants of the drug can be adjusted (shrunk or enlarged) in response to
delivery system’s efficacy. Notably, particle size greatly physiological stimuli. This adjustment significantly
affects clearance through the mononuclear phagocytic improves the retention and penetration of the tuned
system (MPS), with smaller nanodimensional particles particles within tumor cells. Both internal (pH, enzyme,
undergoing reduced uptake by this system. In addition, and redox reactions) and external stimuli (temperature
nanoparticle size plays a critical role in biodistribution, and light) modulate the morphology (shape and size) of
renal filtration, and vascular infusion within the liver. nanoparticles through the processes such as protonation,
The literature describes that nanoparticles below 50 nm π-π stacking, and hydrogen bonding. As a result, sized-
can easily penetrate endothelial cells and infiltrate liver tuned particle drug delivery systems are utilized for
cells, while smaller particle sizes (approximately 5 nm) are efficient therapy, diagnostics, and bioimaging of cancers.
excreted through renal filtration. The variable pore size Figure 4 illustrates smart polymeric nanocarriers that
(ranging from 200 nm to 1.2 μm) is influenced by leaky exhibit a controlled release of actives within tumor cells,
vasculature and the rapid growth of tumor cells . thereby boosting drug efficiency by modifying the tumor
[40]
[44]
However, larger particles are inefficient at entering microenvironment . Table 2 compiles certain polymeric
tumor cells; they are retained in the surrounding of nanoparticles and their applications for the management
tumor cells but struggle to penetrate dense tumor cells . of various tumor cells.
[41]

Volume 2 Issue 3 (2023) 7 https://doi.org/10.36922/td.1356