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

Table 4 Comparative summary of major nanocarriers used in colorectal cancer drug delivery

Nanocarrier class	Representative examples	Key properties	Main advantages in CRC	Main limitations	Typical applications in CRC
Polymeric nanoparticles	PLGA, PEG-PLGA, polymeric micelles, polymersomes, nanospheres	Biodegradable, tunable size and surface chemistry, controlled drug release	Good biocompatibility, sustained release, flexible ligand modification, suitable for small molecules and nucleic acids	Possible burst release, formulation complexity, scale-up challenges	Chemotherapy delivery, gene/miRNA delivery, combination therapy, targeted delivery
Dendrimers	PAMAM, poly(propyleneimine), poly(L-lysine) dendrimers	Highly branched 3D architecture, multiple surface groups, high loading capacity	Precise surface functionalization, strong drug/gene conjugation potential, useful for multifunctional systems	Potential toxicity at higher generations, synthesis cost, limited large-scale translation	Targeted chemotherapy, gene delivery, photothermal and photoimmunotherapy
Liposomes	Conventional liposomes, PEGylated liposomes, liposomal nanovaccines	Phospholipid bilayer vesicles with aqueous core, biocompatible, able to carry hydrophilic and hydrophobic cargo	Strong translational maturity, reduced systemic toxicity, good encapsulation flexibility, suitable for immunomodulators	Stability issues, leakage during storage, RES clearance if not optimized	Chemotherapy, metabolic therapy, immunotherapy, vaccine delivery
Nanoemulsions/Lipid nanoparticles	Nanoemulsions, solid lipid nanoparticles, lipid-based nanocarriers	Lipid-rich structure, good solubilization of hydrophobic drugs, oral-delivery potential	Improved bioavailability, useful for colon-targeted and mucosal delivery, relatively low toxicity	Physical instability, limited drug-loading for some agents, formulation sensitivity	Oral delivery, colon-specific release, hydrophobic drug delivery
Quantum dots	Carbon quantum dots, graphene oxide quantum dots, peptide-functionalized QDs	Strong fluorescence, tunable optical properties, nanoscale imaging capability	Theranostic potential, real-time tracking, combined imaging and treatment	Concern about long-term toxicity and clinical translation, especially for non-carbon systems	Imaging, biomarker-targeted detection, theranostics
Iron oxide nanoparticles	Superparamagnetic iron oxide nanoparticles, 5-FU-loaded IONPs, Fe3O4 nanocatalysts	Magnetic responsiveness, imaging capability, possible hyperthermia effects	Useful for image-guided therapy, magnetic targeting, hyperthermia, ferroptosis-related strategies	Need careful control of biodistribution and safety, variable tumor penetration	MRI contrast, magnetic hyperthermia, targeted chemotherapy, sonodynamic/chemodynamic therapy
Gold nanoparticles	AuNPs, antibody-conjugated AuNPs, drug-loaded AuNPs	High surface area, optical responsiveness, good surface functionalization	Useful for targeted delivery, photothermal therapy, receptor-specific systems, signal amplification	Cost, long-term accumulation concerns, translational standardization issues	Chemotherapy enhancement, receptor-targeted therapy, photothermal therapy
Silver nanoparticles	Citrate-coated AgNPs, surface-functionalized AgNPs	Reactive surface, antimicrobial and cytotoxic properties	Potential anticancer activity and carrier function	Greater concern about toxicity and off-target effects, less mature translational profile	Experimental cytotoxic systems, drug delivery carriers
CNTs	SWCNTs, MWCNTs, functionalized CNTs	High aspect ratio, large surface area, strong mechanical and thermal properties	Excellent loading capacity, membrane penetration, useful for photothermal and gene delivery strategies	Biopersistence and safety concerns, regulatory challenges	Drug delivery, gene delivery, photothermal therapy, combination therapy
Hydrogels/nanogel-associated systems	Thermosensitive hydrogels, injectable hydrogels, nanocomposite hydrogels	High water content, local depot effect, controlled release	Strong potential for local delivery, postoperative recurrence prevention, prolonged release	Limited systemic use, formulation-dependent stability, translation still emerging	Local drug delivery, postoperative CRC control, combination immunotherapy

CRC: Colorectal cancer; PLGA: Poly(lactic-co-glycolic acid); PEG: Polyethylene glycol; miRNA: MicroRNA; PAMAM: Polyamidoamine; QDs: Quantum dots; IONPs: Iron oxide nanoparticles; MRI: Magnetic resonance imaging; AuNPs: Gold nanoparticles; AgNPs: Silver nanoparticles; SWCNTs: Single-walled carbon nanotubes; MWCNTs: Multi-walled carbon nanotubes; RES: Reticuloendothelial system; CNTs: Carbon nanotubes.