Integrated Dual-Functional Nanoplatform with Peptide Targeting and Si-CDs Fluorescence: Toward Precise Imaging of Tumor Cells

The diagnosis of tumors urgently requires imaging probes possessing cell selectivity, stable fluorescence signals, and satisfactory biocompatibility. However, the development of peptide-functionalized fluorescent probes still faces challenges, including complex preparation processes and the difficulty in simultaneously maintaining fluorescence stability and selective capability under physiological conditions. This study developed a self-assembly strategy to construct a bifunctional nanohybrid (Peptide-CDs). By utilizing the affinity of the YWYAF motif in the custom-designed peptide (RGDYWYAF) toward carbon materials, the peptide was efficiently integrated with silicon-doped carbon dots (Si-CDs), which exhibit stable fluorescence properties, through interfacial interactions. In this work, the introduction of the peptide not only enables the nanoprobe to recognize tumor cells overexpressing integrins (e.g., HeLa) via the RGD motif but also enhances the photostability of the Si-CDs. After 30 min of UV irradiation, the Peptide-CDs hybrid showed only a 5% loss in fluorescence intensity, markedly lower than the 33% loss observed for pure Si-CDs. Systematic characterization confirmed the successful construction of the hybrid and its biocompatibility (cell viability >97%). Confocal imaging revealed that the fluorescence intensity of Peptide-CDs in HeLa cells was approximately 30% higher than that of pure Si-CDs. Moreover, the fluorescence signal in HeLa cells was significantly stronger than that in 293T cells, demonstrating its selective recognition capability toward cancer cells. This work provides a simple and effective paradigm for nanobio integration, facilitating the construction of high-performance theranostic platforms.