# Polymers and Polymer Nanocomposites for Cancer Therapy +
## 2 Synthetic Polymers and Polymer Nanocomposites
Dendrimers (nanosized synthetic polymers) with nanogold particle (nAu) hybrids have been demonstrated to be unique nanoplatforms for the production of various multifunctional nanodevices in diverse fields of biomedical applications, including drug delivery, diagnostics, and therapies [23]. A thermoresponsive terpolymer made of diethylene glycol methyl methacrylate, oligoethylene glycol methyl methacrylate, and 2-aminoethyl methacrylate was used as a drug carrier for DOX. Hydrolysable carbamate bonds of the terpolymer allowed for nanoparticle disintegration and the release of the drug at various pH levels with or without an enzyme [24]. A pH-responsive drug nanocarrier based on magnetic mesoporous silica nanoparticles (nSi) and PEG-co-poly (vinyl pyridine) (PEG-co-PVP) has been used for DOX release. The research found that the obtained carrier was applicable to an in vivo essay due to favorable particle size and high colloidal stability [25]. A novel controlled drug delivery with dual pH and thermal responses was designed based on the same nSi nanoparticles anchored by g-cyclodextrinrin and coated by poly(N-isopropyl acrylamide). This nanocarrier could have the potential to be used in tumor therapy [26]. The drug Naproxen was entrapped in a copolymer based on methacrylic acid (MMA) and a mesoporous nanostructured silica (MCM-41). The profiles for in vitro release were established separately in both enzyme-free simulated gastric (SGF, pH 1) and simulated colonic (SCF, pH 7.4) fluids. The release rates of the SCF were higher than those of the SGF. The study also showed that the silanol groups of MCM-41 played a role in drug entrapment efficiency [27]. Using amphiphilic polymers based on PEG and bis-pyrene with a disulfide (SS) bond as reduction linker, a novel nanoparticle system has been obtained that was able to upregulate the reactive oxygen level under UV irradiation in cancer cells, leading to their apoptosis. Maximum release occurred at pH 5.5, the pH of endosomes [28]. To study antitumor targeting and therapy effects, polyaminoamide dendrimers were partially neutralized on their surfaces through the covalent bonding of 2,3-dimethylmaleic anhydride, and DOX was encapsulated in these nanoaggregates to study their antitumor targeting and therapy effects. It was found that these nanoaggregates could realize effective deformation without external additional stimuli for cancer therapy [29]. A nanofiber made of poly(vinyl pirrolidone) as a shell and hyperbranched poly(ethylene adipate) as a core that contained the Artemisinin (ART) drug was produced. An [3-(4,5 dimethyl-2 thiazolyl)] (2,5 diphenyl-2H-tetrazolium bromide) MTT assay showed that this polymer nanocomposite contributed to reducing prostatic cancer cell viability [30]. A polymer nanocomposite made of polyethyleneimine with a zwitterionic function and paramagnetic iron nanoparticles (nFe\({}_{3}\)O\({}_{4}\)) was researched as a carrier for DOX delivery. Studies on magnetic targeting and the evaluation of pharmacokinetic and biodistribution data should be initiated to confirm the efficiency of Fe\({}_{3}\)O\({}_{4}\)@ folic acid (FA)-poly(ethylene amine succinate conjugated)-DOX-loaded nanoparticles as a valuable drug carrier [31]. From a biomimetic point of view, it can be difficult to design, synthesize, and apply polymer therapeutics, but they can offer the advantages of low toxicity, targeting, and selectivity through the incorporation of compounds such as cell signaling and core-shell morphology, which guarantees circulation and accumulation at the site of action. Theranostic characteristics have also been of great importance in new developments [32]. Recent advancements in medicine technologies have provided evidence that besides polymer drug carriers, their nanocomposites have the possibility of replacing conventional drug carriers due to their nonspecificity, lack of side effects, lack of damage to healthy cells, and sensitivity to internal and external stimuli.