A Quantum Dot–Based Platform for Room-Temperature Detection of Dengue Virus RNA

Dengue viruses continue to pose a significant global public health challenge, especially in tropical and subtropical regions where access to centralized laboratory infrastructure is often limited. Prompt identification of dengue virus RNA during the early, acute phase of infection is essential for effective clinical management and timely outbreak response. However, widely used gold-standard techniques such as reverse transcription–polymerase chain reaction (RT-PCR) rely on enzymatic amplification, advanced instru-mentation, and skilled personnel, which restricts their use in point-of-care and re-source-constrained settings. In this work, an enzyme-free nucleic acid detection strategy based on semiconductor quantum dots (Qdots) is described for sensitive and specific dengue virus RNA detection at room temperature. The platform combines toe-hold-mediated strand displacement reactions (TMDRs) for precise sequence recognition with the strong fluorescence and signal amplification capabilities of Qdots. A highly con-served sequence at the 3′ end of the dengue genome was selected to enable detection across all four viral serotypes. Viral RNA is captured by surface-immobilized probes via TMDR, followed by binding Qdot-labeled detection probes and a Qdot-driven signal amplification step, all under isothermal conditions. The assay demonstrated femtomolar sensitivity us-ing synthetic RNA targets and maintained high performance in crude nucleic acid ex-tracts from contrived samples representing all dengue serotypes. Its modular, enzyme-free design offers a simple, rapid, and highly sensitive alternative to conventional amplifica-tion-based diagnostics, with strong potential for low-cost, portable applications in molec-ular diagnostics.