Violet Phosphorus Quantum Dots as Distinguishable Environmental Biosensors

A molecular probe is demonstrated to be an effective semi-invasive technique to measure the local environments of biomaterials. Environmental probes based on fluorescence intensity and lifetime are well studied as temperature sensors. However, usually both fluorescence intensity and lifetime of reported molecular probes depend on various local environments, such as temperature, pH, and ionic strength. It is a big challenge to distinguish the specific environmental effects on the fluorescence. Herein, the violet phosphorus quantum dots (VPQDs) are demonstrated to be effective fluorescence molecular probes to distinguish temperature or pH environment variation. The fluorescence intensity and bandwidth of VPQDs are demonstrated to be linearly correlated to a wide range of temperatures (283–363 K), while the fluorescence lifetime of VPQDs is demonstrated to be temperature-independent. However, the fluorescence lifetime is demonstrated to be linearly correlated to pH value. Additionally, good water dispersibility, superior photo- and thermal stability, and excellent reversibility are also obtained by VPQDs. More importantly, the high sensitivity of fluorescence intensity to temperature instead of pH environments and the high sensitivity of fluorescence lifetime to pH environments instead of temperature allow VPQDs to be distinguishable biosensors to temperature and pH environments.