Oligonucleotide-polymer nanoparticle conjugates: diagnostic applications

The paper aims to review the recent studies investigated in this laboratory on the preparation, properties and applications in the biomedical field of oligodesoxyribonucleotides (ODN)-latex conjugates. Hydrophobic and hydroph ilic nanoparticles proved to be suitable supports for such ss-DNA fragments , preferentially when they are cationically charged regarding the negativel y-charged phosphates of ODNs in a broad range of pH values. The adsorption and desorption behaviour of these ODNs onto latex particles needed to be in vestigated before carrying out their covalent grafting. Several parameters were found to play a role in adsorption behaviour such as pH, ionic strengt h, surface charge density and HLB of the particle interface. Covalent coupl ing of ODNs was performed through the amino terminated alkyl spacer of the ODA, the efficiency of grafting being monitored by selecting the pH, salini ty and adequate non-ionic surfactant. Conformation of immobilized oligonucl eotides can be analysed both by fluorescence energy transfer and neutron sc attering techniques, indicating that basic pH, high ionic strength and high surface grafting of ODNs promoted a brush conformation. Such ODN-bearing n anoparticles were found suitable for enhancing the sensitivity of diagnosti c tests involving DNA capture and detection.