RESUMEN
A novel method combining wet chemistry for synthesis of an Fe core, 532 nm laser irradiation of Fe nanoparticles and Au powder in liquid medium for deposition of an Au shell, and sequential magnetic extraction/acid washing for purification has been developed to fabricate oxidation-resistant Fe@Au magnetic core-shell nanoparticles. The nanoparticles have been extensively characterized at various stages during and up to several months after completion of the synthesis by a suite of electron microscopy techniques (HRTEM, HAADF STEM, EDX), X-ray diffraction (XRD), UV-vis spectroscopy, inductively coupled plasma atomic emission spectroscopy, and magnetometry. The surface plasmon resonance of the Fe@Au nanoparticles is red shifted and much broadened as compared with that of pure colloidal nano-gold, which is explained to be predominantly a shell-thickness effect. The Au shell consists of partially fused approximately 3-nm-diameter fcc Au nanoparticles (lattice interplanar distance, d = 2.36 A). The 18-nm-diameter magnetic core is bcc Fe single domain (d = 2.03 A). The nanoparticles are superparamagnetic at room temperature (300 K) with a blocking temperature, T(b), of approximately 170 K. After 4 months of shelf storage in normal laboratory conditions, their mass magnetization per Fe content was measured to be 210 emu/g, approximately 96% of the Fe bulk value.
RESUMEN
This review explores the recent chemotherapeutic work on drug delivery using nanoparticles as carriers for the targeted treatment of cancer. Compared to direct drug delivery, delivery through a carrier can increase the efficacy of a drug, but decrease the side-effects by utilizing the enhanced permeability and retention (EPR) effect and tumor-specific targeting. The search for efficient and safe transport vehicles (carriers) to achieve better drug availability at the target site has been a challenging yet exciting area of research. Current interest focuses on the colloidal nanoparticles (diameter <500 nm), including the biodegradable polymer- and liposome-systems, bioconjugating with antitumor drugs. These biocompatible nanoparticles, with an enlarged surface area-volume ratio can overcome non-cellular and cellular-based mechanisms of resistance and increase the selectivity of drugs towards cancer cells, while reducing their toxicity towards normal tissues. This review focuses on the evolution of nanoparticles as carriers for anticancer drug delivery, with emphasis on the biocompatible magnetic nanohybrids.