Synthesis And Gas-liquid Interfacial Property Study Of Nucleo-based Amphiphiles

Nucleolipids are amphiphilic hybrid molecules composed of a lipid covalently linked toa nucleobase, or a nucleoside, or a nucleotide or an oligonucleotide. In aqueous solution,nucleolipids are known to spontaneously assemble into a large variety of aggregatedstructures with specifc geometries, such as vesicles, fibers or nanoparticles, because of thecombination of molecular recognition (e.g., H-bonding, π-stacking, etc.) of nucleotides andthe unique aggregation properties of lipids. Based on these properties, nucleotide-basedamphiphiles may have broad prospect in the field of supramolecular materials, drug deliverysystems, and gene transfection. A method of hydrophobic modification at the3’ terminal isdescribed, and a series of Cn-3’-TMP(IV) are synthesized through four steps includingcoupling, oxidation, detritylation and deprotection of cyanoethyl. In addition, wefunctionalize this nucleo-based amphiphile by the introduction of the2-nitrobenzylphotosensitive group between the nucleotide and the aliphatic chain, in order to change theconformation of assemblies through specific light (365nm), and then for the development ofadvanced drug delivery systems, controlling drug release. ESI-MS,1H-NMR and13C-NMRdata show the high purity of Cn-3’-TMP (IV) and photolabile Cn-3’-TMP(IV), confirming thefeasibility of the synthesis scheme. Then we studied gas-liquid interfacial property ofCn-3’-TMP (IV) and photolabile Cn-3’-TMP (IV) in0.2M pH8.0PBS buffer at25°C throughsurface tension method. Similar to gemini surfactants, when the alkyl chain length reaches acertain value, interfacial properties of the two series of compounds deviate from the previoustrend, for Cn-3’-TMP(IV), the length is18, while for photolabile Cn-3’-TMP, is16. For thesame series of compounds, before alkyl chain length reaches the turning point, with the lengthincreasing, CMC decreases, and the measurement of adsorption efficiency pC20increases;when the alkyl chain length reaches the turning point, the CMC values of these two series ofcompounds no longer decrease and become even larger than that of the previous compound,meanwhile, the pC20values also decrease contrast to the previous compound, suggesting thedecrease of adsorption efficiency at the surface. Otherwise, for Cn-3’-TMP (IV), when thealkyl chain length is not more than16, both the logCMC and pC20values are linear functionsof the number of carbon atoms in the alkyl chain. Simultaneously, for Cn-3’-TMP (IV), when the length of the alkyl chain is12,14and16, as the length increases, saturation adsorptionamount Γmax increases and minimum area per molecular Amin decreases,.