Towards label-free mid-infrared protein assays: in-situ formation of bare gold nanoparticles for surface enhanced infrared absorption spectroscopy of bovine serum albumin

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• 作者：Ángela Inmaculada López-Lorente ; Pei Wang ; Boris Mizaikoff
• 关键词：ATR ; SEIRA ; FTIR ; Scanning electron microscopy ; MIR waveguide ; Evanescent wave ; BSA ; Adsorption isotherm
• 刊名：Microchimica Acta
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：184
• 期：2
• 页码：453-462
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Nanochemistry; Nanotechnology; Characterization and Evaluation of Materials; Analytical Chemistry; Microengineering;
• 出版者：Springer Vienna
• ISSN：1436-5073
• 卷排序：184

文摘

Surface enhanced infrared absorption spectroscopy (SEIRAS) with attenuated total reflection (ATR) configuration has been used to determine bovine serum albumin (BSA) protein adsorbed onto bare gold nanoparticles (AuNPs). The AuNPs forming the SEIRA-active substrate were directly synthesized inside the ATR liquid cell taking advantage of stainless steel assisted synthesis via the walls composing the ATR compartment. The formation of the AuNPs can be directly monitored via the enhancement of the corresponding water absorption features. The absorbance of BSA at the AuNPs deposited onto the Si ATR waveguide is significantly enhanced when compared to bare Si, thereby improving the sensitivity of detection. Apparently, the presence of the AuNPs layer at the ATR waveguide surface at the measured conditions does not affect the secondary structure of the protein. Measurements were performed in water and confirmed in deuterium oxide, which significantly reduces the strongly absorbing mid-infrared background of water in the spectral regime of interest. The limits of detection achieved for BSA protein analysis in water and deuterium oxide media are 1.93 and 4.15 mg·L−1, respectively, and the precisions at a 250 mg·L−1 concentration are 11.9% and 8.1%, respectively.