The work is a cooperative effort between the University of Utah and Kazan State University in Russia. The work is based on sintered silica colloidal crystals (nano-frits) with the goal of developing membranes containing nanoscale pores whose surface is modified with thiacalixarene receptors. These receptors, capable of binding ions, small molecules and biomacromolecules, will be covalently attached to the nanopore surface, which will produce nanoporous membranes with selective and environmentally responsive molecular transport. The US and Russian teams possess expertise in the fields of surface-modified silica nanoporous materials and synthesis of thiacalixarenes, respectively. The two groups will complement each other in creating new types of nanoporous materials that will find applications in separations and sensing. Furthermore, this work will be of mutual interest and importance as the two groups will contribute equally to the research and will bring to the table two sets of skills, otherwise not available.
The interaction between the two teams will use cyberinfrastructure. Specifically, infrastructure will be built to enable the interaction between the two research groups using the Internet and videoconferencing. Two conference rooms, at the US and the Russian team locations, are built and equipped for videoconferencing and face-to-face interactions over the Internet. Thus, joint meetings will be conducted every month with the participation of all students and researchers involved in the project. Moreover, this infrastructure will enable everyday communication between researches working in two labs, which will greatly facilitate the cooperative effort. Also, students from both research teams will participate in one extended (1-3 months) stay each year in the counterpart university. In addition, exchange visits of senior participants will take place once a year for 1-2 weeks. These visits will include formal presentations to the research groups and departmental seminars, as well as informal interactions. All these interactions will expose the students and researchers in both cooperating groups to new scientific approaches and methods, and will widen their cultural horizons.
This award is co-funded by the Division of Materials Research and the Office of International Science and Engineering.
Nanoporous membranes are a class of materials used in separations of pharmaceuticals, biological molecules and in water purification. The goal of our work was to prepare novel nanoporous membranes by attaching designed receptors to the surface of nanoporous membranes mades of silica nanoparticles to obtain memrbanes selective for ions, small molecules and biomacromolecules. This work was a cooperative effort between Zharov research group at the University of Utah, USA, with expertise in preparation of surface-modified nanoporous colloidal materials, and Stoikov research group at Kazan State University, Russia, with expertise in preparation and characterization of selective receptor molecules, thiacalix[4]arenes.The main objectives of the project were: (1) design a variety of thiacalix[4]arene receptors suitable for immobilization on silica surface and study their binding properties in solution; (2) prepare the thiacalix[4]arene-modified nanoporous colloidal membranes (nano-frits); and (3) study the selectivity of molecular transport through thiacalix[4]arene-modified nano-frits as a function of thiacalixarene structure and conformation. In the course of our work we obtained many important results. We sudied the mechanism of molecular transport through thiacalixarene-modified nanoporous colloidal films and showed that selectivity results from surface-hopping. We prepared multiple thiacalixarene moieties, developed their attachment to the silica surface and studied selective interactions of these surfaces with biomacromolecules. We discovered that thiacalixarene form nanoparticles that can be utilized in selective binding. We prepared nanoporous silica membranes surface-modified with thiacalixarenes, aptamers and electroresponsive polymers and demonstrated controlled molecular transport through these membranes. We demonstrated that silica membrane can be used for size-selective separations. We prepared responsive nanoporous membranes using a novel material, gold-coated nanoparticles. Finally, we prepared membranes modified with chiral selectors and showed that they allow to seprate chiral molecules. Our work was reported in 20 peer-reviewed publicaitons, 2 book chapters, 22 contributed and 14 invited talks. In terms of educational impact, four PhD dissertations were defended as the result of the work unded by the grant. This work led to strengthening of an international collaboration, as one US graduate student and 2 Russian scholars exchanged extended visits in the respective laboratories. Many of the publications were co-authored by both collaborating groups. Our work provided fundamental discoveries regarding transport through nanoporous membranes, which will lead to technological advances in the areas of separatoins and sensing.
