In this study, we developed the portable chemiluminescence (CL)-based lateral flow assay (LFA) platform for the detection of cortisol in human serum. Cortisol is well-known as a stress hormone due to its high relevancy for human mental and physical health, such as hypertension or depression. To date, a number of optical devices have provided the sensitive determination of levels of analytes. However, this modality type still requires costly optical modules. The developed CL platform is simply composed of two detection modules along with a loading part for the LFA strip. The LFA membrane contains gold nanoparticle probes conjugated with antibodies against cortisol and horseradish peroxidase (HRP), which can also efficiently increase the luminescent signal by providing many areas for anti-cortisol antibody and HRP. The measured voltage signals coming from the photodiode in a CL reader were compared with a standard microplate reader for the evaluation of accuracy. The linear range observed for cortisol was measured to be 0.78–12.5 μg/dL (R² = 0.99) with a limit of detection (LOD) of 0.342 μg/dL. In addition, the CL-LFA reader showed a high correlation (R² = 0.96) with the standard cortisol console (COBAS 8000, Roche), suggesting that our developed CL-based LFA platform can be usable in situ.

A repeated usable electrode sensor for the measurement of glucose in urine has been developed. For improvement of the selectivity in measuring glucose in urine, we fabricated the Pt electrode coated with multilayered composite of glucose oxidase (GOX) and ascorbate oxidase (AOX). This simple layer structure could deliver more electrons the electrode from glucose oxidation without interferent from ascorbic acids to by firstly oxidizing the ascorbic acids present in urine. Results showed that our newly developed Pt-electrode is capable of quantifying the concentrations of glucose in urine min 0 to max 2,000mg/dL as well as maintaining its detection stability during two hundred times repeated measurements. This repeatable use of the sensor is attributable to the solidified structure of AOX and GOX layer.

The development of multifunctional nanoparticles (NPs) combining individual properties, such as magnetic, luminescence, and optical properties, has attracted significant research interest. In this study, europium (Eu)-incorporating iron oxide nanoparticles (IONPs) with Eu(TTA)₃phen (ET-SIOPs) were successfully designed and shown to have luminescence and magnetic properties. The proposed synthetic method has three steps: (1) IONP synthesis, (2) SiO₂ layer coating (1st coating), and (3) Eu–SiO₂ layer coating (2nd coating). The morphology of the ET-SIOPs was well preserved after the 2nd coating was conducted. According to the photoluminescence (PL) spectra in the range of 500 to 700 nm, the Eu-incorporating SIOPs with Eu(TTA)₃phen (ET-SIOPs) exhibited the highest emission intensity compared to the Eu-incorporating SIOPs synthesized with other Eu precursors. Furthermore, the ET-SIOPs exhibited long-term luminescence stability of 6 months. In addition, this method of double-layer coating can be applied to other materials synthesized with different compositions and shapes, such as MnO and SiO₂ NPs. The findings of this study will not only provide new insights for the synthesis of luminescent-magnetic NPs with long-term luminescence stability and paramagnetic properties, but can also be applied for the design of various multifunctional NPs.