# Polymers and Polymer Nanocomposites for Cancer Therapy +
## 2 Synthetic Polymers and Polymer Nanocomposites  
Polyesters from camphoric acid and group IV B metallocene dichlorides are very effective in inhibiting cancer cell lines, including two pancreatic cell lines. They could represent a new group of anticancer drugs [12]. A dual-responsive amphiphilic random copolymer based on tri (ethylene glycol)-methyl ether methacrylate and [1\({}^{\prime}\)-(2-acryloxy)-3,3\({}^{\prime}\)-dimethyl-6-nitrospiro-(2H-1-benzoylran-2,2\({}^{\prime}\)-indoline)] carrying DOX has proven its effectiveness in the case of cancer therapy [13]. Two novel multistimuli-responsive drugs for theranostic application polymers, an (N-isopropyl acrylamide-co-itaconic anhydride) copolymer and a macrobranched terpolymer resulting from its partial esterification with monometoxy poly (ethylene glycol) (PEG), have been obtained. Their hybrids with Fe\({}_{3}\)O\({}_{4}\) nanoparticles have produced nanocomposite carriers [14]. Nanotechnology has lately gained increased attention for its effective diagnosis and treatment of some cancer tumors. Nanocarriers have been used to replace conventional antitumor drug delivery platforms due to their nonspecificity, the lack of side effects, their burst release, and the lack of damage to normal cells. Nanocarriers improve the therapeutic efficiency of antitumor drugs and are able to provide preferential accumulation at the targeted site. Only a limited number of nanocarriers are clinically approved for their intended actions at targeted sites [15]. As a novel drug delivery system, nanocarriers have an important role in cancer therapy. In contrast to conventional chemotherapeutic drugs with many restrictions, stimuli-responsive delivery systems can carry antitumor drugs that target the specific sites of a tumor. Due to a precise stimuli response effect, drug delivery systems can control the release, reduce the damage to normal tissue and organs, and decrease side effects [16]. Polyester/ether urethanes (PURs) can be an interesting alternative for the preparation of nanocarriers in the place of traditionally used biodegradable polyesters. PURs can be easily designed to modulate a hydrophilic/hydrophobic balance and to embed specific functionalities, thus representing a promising solution as a targeted delivery system [17]. Poly (cyclotriphosphazene-co-dopamine) microspheres as controlled drug carriers were investigated using acriflavine as a model drug. The microspheres had a 19.5-mgg\({}^{-1}\) drug storage capacity and sustained release properties of up to 7 days, with 29% (pH 5.0) and 47% (pH 7.4) at 37 \({}^{\circ}\)C [18]. Nanopolymers such as poly(lactic acid) (PLA), PEG, poly(vinyl pirrolidone-co-vinyl acetate) copolymer, poly(acrylic acid) (PAA), and poly(vinyl alcohol) (PVA)-co-albumin copolymer for the nanodelivery of the Sorafenib drug have been reported [19]. Polyurethane (PU)-DOX nanoparticles were prepared in water through electrostatic interactions between amphiphilic PU and carboxyl pending groups (PU-COOH and DOX HCl). The tests performed demonstrated that PU-DOX nanoparticles had a higher level of cellular internalization and a higher inhibition effect on the proliferation of breast cancer (MCF-7) cells than did pure DOX [20]. Heparin-biotin/heparin/CaCO\({}_{3}\)/Ca phosphate/deoxyribonucleic acid (DNA)/DOX nanoparticles exhibited pH sensitivity and tumor-targeting characteristics due to the presence of inorganic components and biotin in the macromolecular chain [21]. Spherical nanopolymers (200 nm) based on poly (l-lactide-co-glycolic acid) (PLGA), which has been used for biomedical applications and on the biopolymer poly(3-hydroxy butyrate) P(3 HB), were used for the core formation and delivery of Docetaxel (DTXL). No significant difference was observed in terms of the internalization rate and cytotoxicity potential. The research demonstrated that P(3 HB) could be a valid alternative to the more conventional PLGA for the delivery and controlled release of hydrophobic therapeutic molecules [22].