New naphthalimide modified polyethylenimine nanoparticles as fluorescent probe for DNA detection

A new naphthalimide modified polyethylenimine (PEI) nanoparticles (called NPEI-NPs) was synthesized and applied as fluorescent probe for rapid, selective and sensitive fluorometric detection of trace DNA. The synthesis involved the covalent modification of PEI with 4-butylamino-N-carboxymethyl-1,8-naphthalimide(BACMN) for getting amphiphilic polymer. Then the amphiphilic polymer was self-assembled in water to give the NPEI-NPs. NPEI-NPs was soluble in water and emitted fluorescence at 545 nm with exciting at 460 nm. The fluorescence spectra resulting from the interaction between NPEI-NPs and DNA indicated that the fluorescence of NPEI-NPs increased in the present of DNA. Therefore, a fluorescence enhancement method was developed for the determination of trace fish sperm DNA (fsDNA) and calf thymus DNA (ctDNA). Under the optimal conditions, the calibration curves were linear over the concentration ranges of 0.05–2.8 μg/mL for fsDNA and 0.08–3.0 μg/mL for ctDNA. The detection limits for fsDNA and ctDNA were 1.6 and 2.0 ng/mL, respectively. The proposed method has been employed to quantify DNA in synthetic samples with the satisfactory results.

Nanoparticles resulted from the self-assembly of naphthalimide modified polyethylenimine. Fluorescence of the nanoparticles was enhanced by increasing the DNA concentration.Figure optionsDownload as PowerPoint slideHighlights
► Naphthalimide modified PEI nanoparticles was developed as new DNA fluorescent probe.
► DNA condensing property and water-solubility of PEI were utilized in probe design.
► Fluorescence-enhanced DNA detection was achieved at 545 nm with exciting at 460 nm.
► The detection limits for fsDNA and ctDNA were 1.6 and 2.0 ng/mL, respectively.