Angelatos Alexandra S, Wang Yajun, Caruso Frank
Centre for Nanoscience and Nanotechnology, Department of Chemical and Biomolecular Engineering, The University of Melbourne, Victoria 3010, Australia.
Langmuir. 2008 Apr 15;24(8):4224-30. doi: 10.1021/la703647y. Epub 2008 Mar 5.
We report a fluorescence-based approach to probing the conformation of a macromolecule, poly(allylamine hydrochloride) (PAH), in bimodal mesoporous silica (BMS) particles. The method involves monitoring the fluorescent properties of the probe, 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt (4-PSA), upon electrostatic binding to PAH molecules adsorbed in the nanopores of the BMS particles. PAH infiltration into the BMS particles, quantified by thermogravimetric analysis and visualized by confocal laser scanning microscopy, was examined as a function of PAH adsorption time, PAH molecular weight, and the sodium chloride (NaCl) concentration and pH of the PAH adsorption solution. The conformation of PAH molecules in the nanopores was investigated by incubating the PAH-loaded BMS particles in 4-PSA and using the ratio of the excimer to monomer emission intensity to discern differences in the PAH conformation in the nanopores. Control experiments involving nonporous silica (NS) particles were also conducted to determine the extent to which the nanopores within the BMS particles influence the degree of PAH adsorption and the conformation of the adsorbed PAH molecules. The data indicate that PAH molecules adsorbed in the nanopores adopt a more coiled conformation than PAH molecules adsorbed on NS particles over a wide range of conditions. Further, the conformation of PAH molecules in the nanopores can be tuned by adjusting the NaCl concentration and/or pH of the PAH adsorption solution. 4-PSA titration experiments revealed that at saturation binding there are ca. 3.8 PAH monomer units per 4-PSA molecule. This study provides insights into macromolecule infiltration and conformation in nanopores, which are important for the application of mesoporous materials in the fields of adsorption/immobilization, catalysis, delivery, sensing, separations, and synthesis.
我们报道了一种基于荧光的方法，用于探测双峰介孔二氧化硅（BMS）颗粒中大分子聚（烯丙胺盐酸盐）（PAH）的构象。该方法包括监测探针1,3,6,8-芘四磺酸四钠盐（4-PSA）在与吸附于BMS颗粒纳米孔中的PAH分子发生静电结合时的荧光特性。通过热重分析对PAH渗透到BMS颗粒中的情况进行定量，并通过共聚焦激光扫描显微镜进行可视化，研究了PAH渗透情况与PAH吸附时间、PAH分子量以及PAH吸附溶液的氯化钠（NaCl）浓度和pH值之间的关系。通过将负载PAH的BMS颗粒置于4-PSA中孵育，并利用准分子发射强度与单体发射强度的比值来识别纳米孔中PAH构象的差异，从而研究纳米孔中PAH分子的构象。还进行了涉及无孔二氧化硅（NS）颗粒的对照实验，以确定BMS颗粒内的纳米孔对PAH吸附程度和吸附的PAH分子构象的影响程度。数据表明，在广泛的条件下，吸附在纳米孔中的PAH分子比吸附在NS颗粒上的PAH分子具有更卷曲的构象。此外，通过调节PAH吸附溶液的NaCl浓度和/或pH值，可以调整纳米孔中PAH分子的构象。4-PSA滴定实验表明，在饱和结合时，每个4-PSA分子约有3.8个PAH单体单元。这项研究为纳米孔中大分子的渗透和构象提供了见解，这对于介孔材料在吸附/固定、催化、递送、传感、分离和合成等领域的应用具有重要意义。
