Fabrication of biocompatible magneto-fluorescence nanoparticles as a platform for fluorescent sensor and magnetic hyperthermia applications

Multifunctional nanoparticles with special magnetic and optical properties have been attracting a great deal of attention due to their important applications in the bioanalytical and biomedical fields. In this study, we report the fabrication of biocompatible magneto-fluorescence nanoparticles consisting of carbon dots (CDots) and silica-coated cobalt–manganese nanoferrites (Co(0.5)Mn(0.5)Fe(2)O(4)) (CoMnF@Si@CDots) (MagSiCDots) by a facile hydrothermal method. The as-prepared MagSiCDots have a particle size of 100–120 nm and show a negative zeta potential of −35.50 mV at a neutral pH. The fluorescence spectrum of the MagSiCDots nanoparticles consists of sharp excitation at 365 nm and broad blue light emission with a maximum wavelength of 442.5 nm and the MagSiCDots exhibit superparamagnetic behaviour with a saturation magnetization of 11.6 emu g(−1). The potential of MagSiCDots as a fluorescent sensor and be used for magnetic hyperthermia applications. It is seen that the fluorescent intensity of a colloidal solution (a hydrogen sulfide (H(2)S) solution containing MagSiCDots nanoparticles) has a linear relationship with the H(2)S concentration range of 0.2–2 μM. The limit of detection (LOD) of H(2)S by our MagSiCDots particles is 0.26 μM and they remain stable for at least 90 min. To test the suitability of the MagSiCDots nanoparticles for use in hyperthermia application, induction heating using an AMF was done. It was observed that these nanoparticles had a specific absorption rate (SAR) of 28.25 W g(−1). The in vitro and in vivo cytotoxicity of MagSiCDots were tested on HeLa cells lines. The results show a cell viability of about 85% when exposed to 100 μg mL(−1) concentration of the particles. The in vivo cytotoxicity using zebrafish assay also confirmed the non-toxicity and biocompatibility of the nanoparticles to living cells. The reported data demonstrate that by combining CoMnF@Si and fluorescent CDots into a single system, not only nontoxic multifunctional nanomaterials but also multimodal nanoparticles for several applications, such as hazard gas detection and acting as a biocompatible heat source for therapeutic treatment of cancer, are provided.