SGER: Protein Interactions with Nano-Scale Controlled Surfaces: Non-Fouling Mechanism

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Shaoyi JiangU of Washington"SGER: Protein Interactions with Nano-Scale Controlled Surfaces: Non-Fouling Mechanism."Non-fouling surfaces are critical to the performance of biosensors and biomaterials.Despite of their importance and enormous effort, non-fouling mechanism is still unknown at present. Many experiments remain unexplained and many controversial issues remain unresolved. There exist several models attempted to elucidate non-fouling mechanism. However, there is a lack of a unified model (or hypothesis), which can explain various experiments and identify the origin of non-fouling surfaces. Among several theoretical studies, either protein molecules are not included, or simplified protein models with continuum medium are used. The novelty of this proposed work is its hypothesis that nano-scale structures of a surface are responsible for protein adsorption/resistance and its integrated experimental and simulation approach designed to prove the hypothesis. In the proposed work, the state (e.g., ieliquid crystalli or ircrystall.) of polyethylene glycol (PEG) terminated self-assembled monolayers (SAMs) will be altered by forming the SAMs at different temperatures or by adjusting the composition of mixed PEG and OH terminated SAMs. Protein adsorption on these surfaces will be measured using surface plasmon resonance (SPR) biosensors. Atomic force microscopy (AFM)/scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), Fourier transform IR spectroscopy-attenuated total reflection (FTIR-ATR), and sum frequency generation (SFG) will be used to characterize these SAMs and adsorbed water molecules. In parallel, molecular simulations will be performed to study how protein adsorption/resistance is affected by nano-scale SAM structures by calculating free energy change upon protein adsorption and examining adsorbed water structure near SAM surfaces. The success of this work will advance the fundamental understanding of protein behavior at interfaces and provide a guide to design better biosensors and biomaterials. It will meet the urgent need for the detection and identification of chemical and biological substances in many areas from homeland security to environmental monitoring to biomedical applications.