Synthesis of iron oxide quantum dots by non-thermal atmospheric pressure plasma electrolysis: influence of operating conditions and biomedical applications

Abstract

Iron oxide quantum dots (IOQDs) were synthesized in this work using a distinct non-thermal atmospheric pressure plasma (NTAPP) electrolysis technique. The impact of the operational environment on the synthesis process was thoroughly investigated. The physicochemical properties of the synthesized IOQDs were studied using various methods, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and vibrating-sample magnetometry (VSM). Further, a time-resolved spectrofluorometer equipped with a time-correlated single photon counting (TCSPC) system was used to measure the photoluminescence lifetime. To explore their potential in biomedical applications, the cytotoxicity and bio-imaging capabilities of the synthesized IOQDs were evaluated through in vitro studies using A549 lung adenocarcinoma cells. A significant finding was the predominant presence of magnetite (Fe₃O₄) over hematite (Fe₂O₃) in the IOQDs, which exhibited notable superparamagnetic properties. Interestingly, the specific operating environment during the synthesis process played a crucial role in determining the properties of the IOQDs. The synthesized quantum dots displayed a straightforward biexponential fluorescence decay profile with an average lifetime of 2.02 nanoseconds. The in vitro analyses confirmed the non-cytotoxic nature of the IOQDs and highlighted their remarkable bio-imaging potential, underscoring their suitability for integration into various biomedical applications.