“…There are several reports that emphasize monitoring spermidine levels in urine, saliva, and biological fluids for early diagnosis of malignancy. − Therefore, it is worth mentioning that although biogenic polyamines remain an essential component for normal physiological functioning, their altered concentrations can have several implications and hence require constant monitoring . In light of these observations, different methods including high-performance liquid chromatography (HPLC), gas chromatography–mass spectrometry (GCMS), thin-layer chromatography, radioimmunoassay, different fluorescent bioprobes using dye-embedded micelles, sol–gel films and conjugated polymers, capillary electrophoresis, and electroanalytical methods have been employed to monitor spermidine concentrations at significantly low limits. − ,, However, the limit of detection that has been achieved so far is at nanomolar concentrations. ,, In this context, there is a driving need for rapid, convenient, reproducible, highly sensitive, and selective determination of spermidine in various biological systems including terrestrial and aquatic life forms, molecular diagnostics, and food industries. Unlike the cost intensive spectrophotometer detection platforms that are commonly used for this purpose, in this study we demonstrate a label-free smartphone-based SPCE detection technique that is portable and economically viable for resource-limited settings.…”