Table 2.

Different types and main characteristics of controlled drug delivery systems for biomedical applications [141, 142]

Controlled drug delivery system	Material	Size	Structure	Types	Fabrication methods	Morphology
Liposomes	Cholesterol Phospholipids	20 nm–10 µm	Lipid based spherical shaped vesicular systems	Multilamellar Single compartment Macrovesicles	Solvent evaporation Solvent dispersion Reverse phase evaporation
Micelles	Phosphatidyl ethanolamine, Phosphatidyl choline, PEG, PVP, PEOz, PEO, PCL, PLA…	10–200 nm	Hydrophilic inner core–Hydrophobic shell architecture	Polymeric micelles Lipid micelles Supermicelles	Solvent evaporation Direct dilution Salting out Dialysis Flash nanoprecipitation
Nanoparticles	PLGA, PEG, PCL, Chitosan, Cholesterol, Palmitate, Au, Si, Ag, Fe, Cu, Pb…	10–300 nm	Nanocapsules, nanospheres, porus speheres	Polymeric Lipid Metal Gold/Silver Magnetic Silica	Solvent evaporation Double emulsion Homogenization Salting out NaBH4 reduction Sol–Gel synthesis
Dendrimers	PAMAM, PPI	20–400 nm	Macromolecules with a regularly branched tree-like structure	Simple, Chiral, Micellar, Hybrid, Metallo dendrimers	Divergent synthesis Convergent synthesis Self-assembly synthesis
Carbon nanotubes	Carbon atoms	0.5–50 nm Ø	Rolled sheets of graphene rings built from sp2 hybridized carbon atoms	SWCNTs, MWCNTs	Laser vaporization Chemical vapor deposition Arc discharge
Hydrogels	Fibrin, collagen, hyaluronic acid, PEG, PVA, PAAM…	–	Natural/ synthetic cross-linked polymers containing a large amount of water	Temperature-responsive hydrogels, pH-responsive hydrogels, Electric-sensitive hydrogels, Ionic strength-sensitive hydrogels	Three-dimensional printing Layer-by-Layer fabrication Microfluidic-based fabrication
Quantum dots	CdSe, CdS, ZnS, PbS…	5–50 nm	Nanosized semiconductor particles with optical and electronic properties	Imaging QDs, Drug delivery QDs, Sensor applications QDs	Colloidal synthesis Plasma synthesis Self-assembled synthesis High temperature dual injection
Polyelectrolyte complexes	Chitosan, PGA, SDS, CMCG, fibroin, SCMC…	20–300 nm	Polymeric matrix with oppositely charged polyelectrolytes with strong but reversible electrostatic links	Nonstoichiometric water-soluble PECs, Stoichiometric insoluble PECs, Turbid colloidal stable PECs, Complex coacervates PECs	Solution spontaneous association Simple PECs titration technique

CMCG, carboxymethyl cashew gum; MWCNTs, Multiple-walled carbon nanotubes; PAAM, poly(acrylamide); PAMAM, poly (amido amine); PCL, Poly (ε-caprolactone); PEG, Poly (ethylene glycol); PEO, poly (propylene oxide); PEOz, poly (2-ethyl-2-oxazoline); PGA, polygalacturonic acid; PLA, poly (lactide); PLGA, poly (lactic-co-glycolic); PPI, poly(propylenemine); PVP, poly (N-vinyl pyrrolidone); SCMC, sodium carboxymethyl cellulose; SDS, sodium dextran sulfate; SWCNTs, Single-walled carbon nanotubes