gainst degradation, targeting the drugs to specific sites of action, organ or tissues, and delivery of biological molecules such as proteins, peptides, and oligonucleotides.

Applications of drug nanoparticles include: both biodegradable nanoparticles for systemic drug delivery and nonbiodegradable nanoparticles for drug dissolution modification have been studied [15-18]. Proposed applications for drug nanoparticles vary from drug targeting and delivery [15, 17, 19-23] to even gene [24-26] and protein [27, 28] therapies. Administration of nanoparticles by, for example, parenteral [16] ocular [29-31] , transdermal [32], and oral routes have been studied. However, the oral route is still the most convenient, preferred, and in a lot of cases, also the most cost-effective route of drug administration [28, 33-37].
There is considerable interest in recent years in developing biodegradable nanoparticles as a drug/gene delivery system [25, 38-41]. An ideal drug-delivery system possesses two elements: the ability to target and to control the drug release. Targeting will ensure high efficiency of the drug and minimize the side effects, especially when dealing with drugs that are supposed to kill cancer cells but can also kill healthy cells when delivered to them. Controlled drug release can decrease or even prevent its side effects.
The advantages of using nanoparticles for drug delivery applications rise from their three main basic properties. First, nanoparticles, because of their small size, can penetrate through smaller capillaries, which could allow efficient drug accumulation at the target sites [42, 43]. Second, the use of biodegradable materials for nanoparticle preparation can allow sustained drug release within the target site over a period of days or even weeks [44-46]. Third, the nanoparticle surface can be adapted to modify biodistribution of drugs or can be conjugated to a ligand to attain target-specific drug delivery [47, 48].