o-Nitrobenzyl photochemistry as induced by UV-A irradiation was applied to a photoactivated drug releasing system based on a molecular beacon strategy. A stem-and-loop structured oligodeoxynucleotide (ODN) possessing a photoreactive o-nitrobenzyl chromophore at the 3′-end and 1-aminonaphthalene quencher at the 5′-end underwent conformational change into a conventional double strand structure by hybridization with a specified target DNA. The intrinsic stem-and-loop structure suppressed photoactivated release of benzoic acid as a phantom drug from the o-nitrobenzyl chromophore because of intramolecular quenching by the 1-aminonaphthalene unit in close proximity to the chromophore. Formation of the double strand structure in the presence of perfectly matched target DNA minimized occurrence of intramolecular quenching and thereby enhanced the photoactivated drug release.
基于分子信标策略,将紫外线-A 照射诱导的邻硝基苄基光化学作用应用于光活化药物释放系统。茎环结构的寡去氧核苷酸(ODN)在 3′端具有光活性邻硝基苄基发色团,在 5′端具有 1-aminonaphthalene 醌淬灭剂,当与指定的目标 DNA 杂交时,该寡去氧核苷酸会发生构象变化,变成传统的双链结构。由于邻硝基苄基发色团附近的 1-aminonaphthalene 单元具有分子内淬灭作用,这种固有的茎环结构抑制了邻硝基苄基发色团光活化释放苯甲酸这种幻影药物。在目标 DNA 完全匹配的情况下形成的双链结构可最大程度地减少分子内淬火的发生,从而提高光激活药物的释放。