# Recent Progress and Challenges Regarding Magnetic-Based Nanoparticles for Targeted Drug Delivery
## 4 Multifunctional Magnetite-Based Nanomaterials
A similar effect was observed for the increased laser power intensity, so the temperature for power 0.5 W/cm\({}^{2}\) increased to 41.5 \({}^{\circ}\)C and for power 2.0 W/cm\({}^{2}\) to 61.5 \({}^{\circ}\)C. Interestingly, the photothermal effect of magnetite or graphene oxide was similar and much lower than that of magnetic graphene oxide. The cytotoxicity studies without and with NIR stimulation confirmed the excellent conversion efficiency of the nanocarrier. The liver cancer cell viability in the presence of the nanocarrier combined with PTT was only 53.3%, while without PTT, the cell survival rate was very high (at least 80%). The DOX-loaded nanocarrier contributed to much lower cell survival (32.5%), which was additionally reduced by photothermal therapy (21.2%), confirming the advantage of combined therapies over single chemotherapy. Another nanoplatform dedicated to DOX delivery and liver cancer treatment comprised a magnetite core covered with a porous carbon(C)/ZnO structure with conjugated FA [102]. The photothermal effect was initially investigated in water for Fe\({}_{3}\)O\({}_{4}\)@C/ZnO-FA and C/ZnO nanocarrier using laser irradiation (638 nm, 1.0 W/cm\({}^{2}\)) and temperature increased by 17 and 15.6 \({}^{\circ}\)C, respectively. The in vitro studies of cell viability and in vivo tumor size proved the synergistic effect of DOX and PTT against liver cancer cells. The killing effect of DOX-loaded Fe\({}_{3}\)O\({}_{4}\)@C/ZnO-FA was very high (73%) but significantly improved (90%) under a 638 nm laser irradiation. Additionally, the mice treated with DOX-loaded Fe\({}_{3}\)O\({}_{4}\)@C/ZnO-FA + PTT had the longest survival time (12 days) and the highest survival rate (78%). Another approach for synergistic liver cancer therapy was designed using crosslinked hydroxypoyl cellulose and carboxymethyl chitosan as an injectable hydrogel with loaded magnetite, photosensitizer black phosphorous (BP) nanosheets, and reactive agent ante-sunate (ART) [103]. ART is a first-line antimalarial drug, but it demonstrates auspicious anticancer properties as it inhibits the growth of hepatocellular carcinoma cells. The synergistic effect on tumors was studied using free ART, ART-loaded hydrogel, ART-loaded hydrogel+NIR, ART-loaded hydrogel+magnetic field (MF), and ART-loaded hydrogel+NIR+MF. In turn, camptthecin (CPT) was loaded into magnetic graphene oxide coated with a \(\beta\)-cyclodextrin-choline acid (CA)-hyaluronic acid (HA) polymer for hepatocellular carcinoma therapy [104]. The material showed excellent photothermal stability and conversion efficiency as the solution temperature rose from 47 to 71 \({}^{\circ}\)C (from 0.1 to 1.0 mg/mL) upon NIR irradiation (808 nm, 15 min, 2.0 W/cm\({}^{2}\)). In vivo studies with tumor-bearing mice were carried out using different irradiation times (1-5 min), and the temperature of the tumor site grew to 58 \({}^{\circ}\)C. After 21 days of treatment, the group treated with CPT-loaded nanoplatform + NIR demonstrated the most substantial antitumor effect (90%). Among the nanosystems dedicated to breast cancer therapy, magnetite-modified graphene oxide was again applied by [PERSON] et al. [105]. After functionalization with hydroxypoyl cellulose and loading with PTX, it was tested in combined chemotherapy and PTT. The photothermal performance (808 nm, 1.0 W/cm\({}^{2}\), time 6-10 min) was investigated using different concentrations of the nanoplatform (Figure 7). The higher the concentration of the nanocarrier, the more significant the temperature increase. Finally, the temperature of the nanobiocomposite solution (1 mg/mL) increased from 18.2 to 59.8 \({}^{\circ}\)C after 10 min of laser irradiation, confirming excellent light-transform capability. On the other hand, liposomes containing magnetite and a cardiotonic steroid--butfalin (BFL)--were investigated using different Fe\({}_{3}\)O\({}_{4}\) concentrations (10-300 mg/mL) [106].