Synthesis of Orange Peel–Derived N and P Doped Carbon Quantum Dots/Manganese Hexacyanoferrate Nanocomposite for Ultrasensitive Detection of Sneprin

The growing environmental and clinical concerns associated with sneprin residues necessitate the development of rapid,
cost-effective, and ultrasensitive detection strategies. To address this, N, P doped carbon quantum dots (NPCQDs) are
derived from orange peel via a green hydrothermal approach, were integrated with manganese hexacyanoferrate (MnHCF)
to fabricate a hybrid nanocomposite. The rationale behind this design lies in the synergistic combination of the redoxactive
centers of MnHCF with the high conductivity, abundant surface functional groups, and sustainable origin of NPCQDs,
which overcomes the inherent drawbacks of pristine MnHCF such as low conductivity and limited stability. The
resulting MnHCF/NPCQD hybrid was thoroughly characterized by XRD, FTIR, SEM, HRTEM with EDS and XPS
analyses, confirming a crystalline MnHCF framework with uniformly distributed NPCQDs. Electrochemical investigations
using CV, DPV, and EIS revealed enhanced redox activity, surface-controlled kinetics, and significantly reduced
charge transfer resistance. The MnHCF/NPCQD-modified glassy carbon electrode exhibited a linear response range of
10–200 μL, high sensitivity of 1.37 μA/μL, and a low detection limit of 3.63 μL. Moreover, the sensor retained 93.8%
of its initial response after 30 days, demonstrating excellent stability and reproducibility. This sustainable hybridization
strategy highlights the potential of MnHCF/NPCQD as a high-performance electrochemical platform for real-time sneprin
monitoring in pharmaceutical and environmental applications