The number of cancers overtaken patients is increasing day by day (Anand et al.; Vallet-Regí et al., 2003; Vasir and Labhasetwar, 2005; Wang et al., 2007; Lee et al., 2012; Anand et al., 2017). one of the most common types of cancer, especially in women is breast cancer, and, unfortunately, its cancer suffering patients is increasing each year (Smith, 2003; Jemal et al., 2011; Gavas et al, 2021, Quazi, 2021). It is widely studied and accepted that breast cancers are hormone-dependent and that is estrogen which a key mediator in the progression and metastasis of breast cancer (Yue et al., 1998). Letrozole is one of the most effective third-generation of non-steroidal aromatase inhibitors (AIs) that can inhibit excess estrogen biosynthesis in the body (Smith, 2003; Vallet‐Regí et al., 2003; Wang et al., 2007; Jemal et al., 2011). Letrozole uses as positive drug to treat breast cancers and highly potent drugs due to its estrogen receptor (Furet et al., 1993; Lang et al., 1993; Mondal et al., 2008; Saboktakin et al., 2011).
Some strong steps for the treatment of cancer are required to develop new technology. One of the ways to kill the cancer cells by using targeted drug delivery in which the word “targeted” is referred to kill only cancerous cells without any harm of healthy cells. Recently, spinel ferrites have attracted much attention for their potential use in biomedical applications like controlled drug delivery, cell separation, magnetic resonance imaging (MRI) and localized hyperthermia and, etc. (Dey et al., 2017; Dhal et al., 2017; Ramasamy et al., 2017; Zhao et al., 2017; Quazi, 2021). Among them, Cobalt ferrite (CoFe2O4) has particular significance because of its remarkable magnetization property such as high coercivity, moderate saturation magnetization, high Curie temperature, large magneto crystalline anisotropy, high mechanical hardness, and remarkable chemical stability, also appropriate biocompatibility and low toxicity (Zhao et al., 2006; Goh et al., 2010; Sivakumar et al., 2012). Furthermore, they can be directly injected into cancer cells and delivered by magnetic field gradient or delivered by other efficient drug delivery systems to release their drugs (Sharma et al., 2015; Quazi, 2021).
So far, various magnetic nanoparticles with different formulations have been synthesized for cancer therapy which to improve biomedical applications, surface modification is necessary to coat them with stimuli-responsive(Sundaresan et al., 2014; Unsoy et al., 2014; Ghorbani et al., 2015). Methionine is one of the most crucial and primary biocompatible amino acids in the human body, which has specialized in vivo physiological purposes. Three activated functional groups of Methionine (-COOH, -NH2 and -SH), could be simply applied for the conjugation of metal atoms(CoFe2O4) which can use as the surface of a carrier to examine the loading and release behaviors that have not yet been reported(Fan et al., 2016; Wang et al., 2017). In 2018 Guangzhou Wang, Fei Zhou and et al. revealed a facile synthesis of Cobalt Ferrite (CoFe2O4) nanoparticles; in the presence of L-cysteine (Lys) which can serve as a great carrier to cancer therapy(Wang et al., 2018; Quazi, 2021). Also Amoli-Diva and et al. reported FeMn2O4 nanoparticles coated with (TEOS) and modified with 3-mercaptopropionic acid (MPA) can be a suitable candidate for site-specific and controlled anti-cancer delivery.
In this research, synthesis and application of smart core/shell CoFe2O4 nanoparticles were reported which coated with methionine through the reflux assay in one step and used as a carrier of an anti-cancer drug. Nanoparticles were characterized by XRD, SEM, TEM, VSM, TGA, and FT-IR techniques. Letrozole was used as an anti-cancer model drug and the drug loading and drug release behavior of methionine-coated CoFe2O4 nanoparticles reported. Furthermore, it was reported that CoFe2O4@Methionine in vitro cytotoxicity was evaluated by MTT assays with varying concentrations on two cancer cell lines and normal cell line at 24,48,72 h.