Background: covalent organic frameworks (COFs) are a class of porous materials with a crystalline structure, composed of organic building blocks linked by covalent bonds. Their unique structure (such as their 2D and 3D versatility) and properties make them promising materials for biomolecule detection. Due to their large surface area and well-defined pores, COFs can selectively interact with biomolecules, enabling sensitive and specific detection methods. These attributes make COFs attractive for applications in medical diagnostics and other areas where biomolecule detection is crucial. Methods: the researchers synthesized p-3D-COF-NS by performing [2+2] imine condensation reactions between p-phenylenediamine (2D-C₂) and 2,5-furandicarboxaldehyde (2D-C₂) building blocks. Initially, 2D sheets were formed, but these were later converted into a stable pseudo-3D structure through bond angle changes. Exfoliation techniques were employed to produce nanosheets with improved productivity and reduced π stacking. The detection of biomolecules, including the Covid-19 virus, was performed using fluorescence-based techniques. Results: the synthesized p-3D-COF-NS demonstrated promising potential as a probe adsorbent material for biomolecule detection. The researchers achieved sensitive and selective fluorescence-based detection of biomolecules, including the Covid-19 virus, using the developed nanosheets. The low detection limit of 2 picomoles indicates the high sensitivity of the method. The use of COFs as quenchers in biomolecule detection offered advantages over traditional graphene oxide due to their inherent pore structure, large surface area, specific channel structure, multidimensionality, and stability. Conclusion: the study contributes to the expanding field of COF chemistry and highlights the potential applications of COFs in various areas, including drug delivery, disease detection, electronics, and membrane separation. The development of pseudo 3D imine-based COF nanosheets represents a significant advancement in the design of biomolecule detection materials. The demonstrated sensitive and selective fluorescence-based detection of biomolecules, including the Covid-19 virus, showcases the potential implications of this research in medical diagnostics and disease monitoring.