Bridging environmental and biological monitoring: Constructing platform for hexavalent chromium detection and cancer-cells screening based on red fluorescent carbonized polymer dots

•Rational designed R-PDs was obtained through facile hydrothermal method.•A high-throughput scanometric analysis platform of Cr(VI) was constructed.•Visual imaging analysis of Cr(Ⅵ) in living cells and in vivo was realized.•R-PDs was successfully used for distinguishing cancerous and normal cells. Intensive research on biocompatible carbon-based fluorescent nanomaterials provides a brand-new platform for environmental and biological monitoring, but its applicability is limited by the single signal response, unfriendly synthesis route, or rare red fluorescence performance. In this study, we designed and prepared a new type of high-efficiency red fluorescent carbonized polymer dots (R-PDs) through rationally preferred raw materials. The proposed R-PDs with colorimetric and fluorescent dual-signal response to hexavalent chromium (Cr(VI)) can be obtained easily by hydrothermal treatment of o-hydroxybenzoic acid and p-phenylenediamine. A high-throughput smartphone-mediated scanometric analysis platform was constructed based on sensitive gray change, which was further applied for the rapid, simple, and low-cost detection of Cr(VI) in real environmental water. The fluorescent analysis mode exhibits high sensitivity with the limit of detection 20 nM, thereby realizing the Cr(VI) imaging in living cells and aquatic species. More importantly, R-PDs exhibited excellent nucleolus targeting capacity by virtue of their inherent high nitrogen content, thus successfully screening normal and cancerous cells. Encouraged by the simplicity of synthesis and availability of constructed analysis platform, the proposed R-PDs has great potential applications in environmental monitoring, biosensing and biomedical.