Characterization Of Biological Amphiphilic Molecules And Its Application In Controlled Release

In the past decades,biological amphiphiles attracted scientises’attention according to their biocompatibility and molecular recognition.Numerous biomolecule based amphiphiles were reported and systematically investigated.Nucleolipid is hybrid molecule with nucleoside/nucleotide as hydrophilic head and lipid as hydrophobic segment.It has been applied as drug delivery vesicles,gene transfer vector and building blocks to construct complex supramolecular structures.In this thesis,we investigated the role of H-bond in nucleolipid’s assembly behavior.To achieve this goal,nucleolipid containing different type of nucleobase and aliphatic chain was synthesized.Their physical properities were investigated and the interaction between the bases was studied by surface tension,UV-vis spectrum,~1H-NMR and FTIR.We found the H-bond between the nucleobase in single-nucleotide nucleolipid could not be ovserved due to its low energy.Therefore,a nucleolipid containg three nucleotides(C_n(dC)_m)was designed.The i-motif secondary structure was observed when aliphatic chain containing more than 14 carbon atom was introduced.Besides,we found that longer aliphatic chain increase the thermal stability of i-motif.These work provides us strategy to stabilize the ultra-short base pair under room temperature.Subsequently,we designed and synthesized a near-infrared red(NIR)light responsive liposome.The NIR responsive 4-bromo-7-hydroxymethyl coumarin(Bhc)unit was incorporated at the alkyl chain of phosphocholine type lipid.Liposomes containg NIR-responsive lipid,cholesterol and POPC was prepared and utilized as Photo-controlled release system.Upon light irradiation,the release of encapsulated payload was preciously controlled by changing light intensity,irradiation time,proportion of light-sensitive molecules.