Fuel theft poses a significant threat to economic stability, undermining governments revenues and global security while benefiting criminal networks. Combating this issue requires coordinated efforts including innovative technological solutions to secure the oil supply chain by ensuring their authenticity and traceability. In that context, this study investigates the development of organic nanoparticles (NPs) involving chitosan-linear poly(ethylenimine) (dCS-LPEI) copolymer enclosing short DNA sequence as a fuel marker. The surface properties of these NPs were modified by acylation in water/acetonitrile (H 2 O/MeCN) 1:1 cosolvent medium to improve their colloidal properties in organic media, which enabled their isolation and resuspension in isopropanol (i PrOH) as stock concentrates. Dynamic light scattering (DLS) measurements were used to assess the NPs colloidal stability at each stage of the functionalization and formulation pathways. The NPs were then diluted to 0.5 ppb in apolar media such as kerosene and diesel, recovered by filtration and disassembled under mild conditions using tripolyphosphate (TPP), inducing the release of the DNA tag which was detected by quantitative polymerase chain reaction (qPCR).