A Nanolasing‐Based Sensor for Ultra‐Sensitive Detection of Trace HSA in Artificial Urine

Abstract Nanolasers represent a novel class of light emission with the advantage of narrower bandwidth, stronger intensity and minimized sizes, which provide ideal platforms for sensing applications. In this study, high performance plasmonic nanolasers gained by 4‐(dicyanomethylene)‐2‐methyl‐6‐(4‐dimethylaminostyryl)‐4H‐pyran (DCM) dye in bio‐environments is achieved and applied to detect human serum albumin (HSA). This innovative approach has established a clear linear relationship between the concentration of HSA and the intensity of nanolasing actions, which provides much higher sensitivity than photoluminescence (PL) (15‐fold). In addition, the spectral bandwidth of nanolasing (≈9.5 nm) is much narrower than normal PL (≈78 nm), resulting in a figure of merit (FOM) value increased by two orders of magnitude. Consequently, the limit of detection (LOD) value provided by the nanolasing based sensor is 14.3 mg L ⁻¹ , which is even better than the commercialized fluorescence spectrometer (77.6 mg L ⁻¹ ). The nanolasing‐based sensor requires only 1/70 of the sample volume (5 µL vs 350 µL), making it particularly valuable for analyzing rare or limited biological samples. This work highlights the significant advantages of nanolasing‐based sensors and establishes a foundation for their broader application in detecting various biomolecules including DNA and proteins.