**4. Micelles**

Micelles have been importantly positioned as a drug carrier [51]. Micelles, which are commonly synthesized from polymers, have been proposed in preclinical studies *Novel Drug Carries: Properties and Applications DOI: http://dx.doi.org/10.5772/intechopen.106868*

**Figure 3.** *Aptamers as drug carrier.*

**Figure 4.** *Micelles as drug carrier.*

for the drug release of poorly soluble chemotherapeutic agents in cancer. Polymeric micelles are created via the self-assembly of amphiphilic polymers [52].

Many polymers have been proposed to produce micelles including poly(lactide) (PLA), poly(caprolactone) (PCL), poly(lactide-co-glycolide) (PLGA), polyesters, poly (amino acids), lipids, poly (ethylene glycol), poly(oxazolines), chitosan, dextran, and hyaluronic acids, among others. Micelles can be prepared on a nanoscale enabling the enhanced permeability and retention (EPR) effect (**Figure 4**). Moreover, the stimuli (pH, hypoxia, enzymes) sensitive breakdown offers the micelles an efficient drug release. These micelles can be degraded using light, ultrasound, and temperature among other external stimuli to perform a controlled release of the drug [52].

Soleymani Abyaneh et al., 2015, prepared a block copolymer micelle containing methoxy poly (ethylene oxide) (PEO) as a shell layer, poly (lactic acid) (PLA) of different stereo-chemistries as the outer core, and poly (α-benzylcarboxylate-ε-caprolactone) (PBCL) or poly(ε-caprolactone) (PCL) as the inner core. The micelles were used as drug carriers of the hydrophobic drug nimodipine, which is a drug used to treat symptoms from a ruptured blood vessel in the brain [53].
