# Polymers and Polymer Nanocomposites for Cancer Therapy +
## 3 Biopolymers and Biopolymer Nanocomposites
(Metoxy-PEG-b-PLA) diblock copolymers were also used as carriers for CUR. These block copolymers were noncovalently loaded with CUR, a CUR bortezomib complex, and a CUR bortezomib model. The results of the research suggested that the mPEG-b-PLA nanoformulations can be useful as carriers of CUR in breast cancer [59]. Dextran/nSi biopolymer nanocomposites were studied as a potential theranostic system for bioimaging and sonodynamic therapy. This type of biopolymer nanocomposite exhibited enhanced stability in water. In vitro experiments revealed the low cytotoxicity of dextran-coated nSi nanoparticles in comparison to uncoated ones, a fact that suggests that the former be used for medical purposes. Therapeutic ultrasound irradiation of cancer cells with the incorporated nSi resulted in a decrease in the number of living cells, while the total number of cells remained nearly constant. The results show the possibilities of applications of porous nSi with dextran coating in both diagnostics and cancer sonodynamic therapy [60]. Two different fluorescent block copolymers of PLA and PEG containing grafted fluorescein were synthesized. Plaxitel-loaded fluorescent microspheres were prepared from the grafted copolymers, and they proved to have anticancer activity against the colorectal cancer cell line Caco-2 [61]. The efficient delivery of Daunorubicin-loaded PLA with multiwall carbon nanotubes (MWCNTs) and iron oxide (PLA/MWCNT/Fe\({}_{3}\)O\({}_{4}\)) composite nanofibrous scaffolds was investigated from the point of view of a proliferation inhibitor effect on leukemia K562 cell lines. The effect of nanofiber concentration on drug delivery in the absence or presence of an external magnetic field was also evaluated. The results indicated that the incorporation of Daunorubicin into prepared nanofiber scaffolds under an applied magnetic field could have synergistic cytotoxic effects on leukemia cancer cells [62]. The clinical applications of DOX have been limited due to its nonselective cytotoxicity, which leads to adverse effects. In recent research, dextran-coated goldmag (GM) nAu/Fe\({}_{3}\)O\({}_{4}\) particles (DGMNs) were synthesized and validated as a potential carrier for DOX. Under the guidance of an external magnetic field, the cytotoxicity of the drug and carrier composite was evaluated in hepatocellular carcinoma cell lines and in tumor grafts. The study showed that DGMNs are a promising drug delivery carrier for magnetically targeted cancer therapy [63]. In order to improve the outcome of chemo-photothermal cancer therapy, poly-\(\gamma\)-glutamic acid-g-poly(lactic-co-glycolic acid) nanoassemblies were developed to serve as carriers of DOX and indocianine green (ICG). Taking advantage of acid-triggered rapid DOX release combined with photoinduced hyperthermia and singlet oxygen generation to facilitate the accumulation of DOX within the nucleus, even at a low dosage, the DOX/ICG-loaded polymer nanoassemblies effectively suppressed the proliferation of cancer cells. Based on the findings, the DOX/ICG-loaded assemblies displayed a great potential for augmenting the efficacy of chemo-photothermal cancer therapy [64]. The use of marine biopolymer (algae)/nanofilers for theranostic applications was evaluated in a recent review, addressing potential uses in drug delivery and various therapies such as photothermal, photodynamic, and hyperthermia therapy as well as photoacoustic imaging, magnetic resonance imaging (MRI), and computed tomography. Although many synthetic polymers and biopolymers are used for surface modifications of Au, Ag, magnetic mesoporous nSi, and other nanoparticles in biomedical applications due to their excellent biocompatibility, biodegradability, nontoxicity, low cost, and abundant renewable sources, the research and development of the theranostic application of marine biopolymer-based nanomaterials is still in its initial exploration phase.