Protein/Peptide Separation with Polymer Brush Nanosponges

描述（由申请人提供）：我们将研究肽和荧光染料分子在纳米长度系留聚合物薄膜（所谓的聚合物刷）上的吸附，以便快速分离化合物混合物，并通过基质辅助激光解吸电离飞行时间（MALDI-TOF）质谱法分析成分。这些水凝胶膜在水溶液中可以膨胀超过一个数量级，这取决于pH值。更具体地说，阴离子刷在高pH值（bbbb6）下膨胀，在低pH值（<6）下由于阴离子羧酸的质子化而坍塌；我们把这些薄膜称为纳米海绵，因为它们的崩塌会引发溶剂的释放（即海绵被挤压）。这种溶剂的释放提供了一种方法，可以将之前通过选择性吸附从混合物中分离出来的分析物释放出来。在这个为期两年的项目中，我们主要感兴趣的是检查刷膜的负载能力（即每单位体积吸附肽的量），以及控制刷膜中化合物的负载和释放的各种结构参数。此外，我们将研究分析物的吸收和释放的时间响应，以及刷膜的崩塌和膨胀。由于这些是纳米膜，我们预计它们的反应将比传统的大块水凝胶膜更快。

DESCRIPTION (provided by applicant): We will examine the adsorption of peptides and fluorescent dye molecules onto nanometer length-tethered polymer films (so-called polymer brushes) in order to rapidly fractionate mixtures of compounds and analyze the components by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry. These hydrogel films can swell by more than an order of magnitude in aqueous solutions, depending on the pH. More specifically, the anionic brushes expand at high pH (>6) and collapse at low pH(<6) due to protonation of the anionic carboxylates; we refer to these films as nanosponges since the collapse triggers a release of the solvent (i.e. the sponge is squeezed). And this release of solvent offers a method to deliver an analyte that had previously been fractionated by selective adsorption from a mixture. In this two-year project we are primarily interested in examining the loading capacity of the brush films (i.e. the amount of adsorbed peptide per unit volume), along with the various structural parameters that control the loading and release of compounds from the brush film. Furthermore, we will examine the temporal response of uptake and release of analytes, along with the collapse and expansion of the brush films. Since these are nanofilms we anticipate that their response will be faster than traditional bulk hydrogel films. The specific objectives of this work include the following: 1) Design and synthesize polymer brush films that will adsorb peptides and/or ionic dyes based on the charge distribution of the molecules and the brush; 2) Demonstrate the rapid uptake and release of the peptides or fluorescent dyes by altering the pH of the solution; 3) Develop structure-property relationships that allow us to maximize the loading capacity and the selectivity of the adsorbed species; 4) Evaluate the efficacy of this approach for peptide/protein fractionation as applied to MALDI analysis for proteomic and metabolomic applications; and 5) Introduce our respective graduate students to biomedical research and encourage undergraduates to pursue Ph.D. degrees in related fields. The films will be synthesized by "grafting from" methodology from self-assembled monolayers that are tethered to gold coated silicon wafers. The resulting films will be characterized by a variety of techniques including: RAIRS, ellipsometry, QCM, AFM, and time-resolved fluorescence spectroscopy. This project is relevant to public health since our long-term goal is to rapidly separate proteins and other biologically relevant molecules from various fluids such as blood, urine, or cultured media. These novel materials act like smart sponges to selectively adsorb specific peptides based on ionic interactions, which will then be analyzed by mass spectrometry.