Synthesis of Sustainable Chromium‐Based Nanoparticles With Fluorescence Tunable Ability for Biosensing of Tumor‐Derived Exosomes and Molecular Information Protection

ABSTRACT Metal nanomaterials have garnered significant attention due to their distinctive physical and chemical properties, which present promising applications in sensing, catalysis, and energy. However, chromium‐based nanomaterials have been relatively overlooked in terms of their synthesis, properties, and applications. This research presents a rapid and efficient method for synthesizing chromium‐based nanoparticles (Cr NPs) with tunable fluorescence capability to detect tumor‐derived exosomes (TDEs) and implement information security at the molecular level. The synthesis process involved a straightforward procedure of mixing pre‐cooled Cr 6+ and NaBH 4 solutions for 30 min. The resultant spherical Cr NPs displayed unique fluorescence modulation (including quenching or enhancing) for various dyes and DNA with different compositions. Leveraging these fluorescence characteristics, a CD63 aptamer–Cr NPs sensing system was constructed for detecting CD63‐positive TDEs even in real samples while encoding and protecting information. In this system, fluorescence‐labeled CD63 aptamers functioned as recognition probes and information carriers, forming a stego object by adsorbing onto the Cr NPs. The specific binding of the CD63 aptamer–Cr NPs to CD63 or TDEs elicited distinct fluorescence responses, thereby enabling precise quantitative detection alongside data encryption and protection. This study provides a new extension for the preparation and application of novel metal nanomaterials, offers a new platform for the rapid detection of tumor biomarkers, and opens up a direction for the integration of sensing and information science based on molecular systems.