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Abstract：
We describe a competitive colorimetric assay that enables rapid and sensitive detection of galactose and reduced nicotinamide adenine dinucleotide (NADH) via colorimetric readouts and demonstrate its usefulness for monitoring NAD+-driven enzymatic reactions. We present a sensitive plasmonic sensing approach for assessing galactose concentration and the presence of NADH using galactose dehydrogenase-immobilized gold nanostars (AuNS-PVP-GalDH). The AuNS-PVP-GalDH assay remains turquoise blue in the absence of galactose and NADH; however, as galactose and NADH concentrations grow, the reaction well color changes to a characteristic red color in the presence of an alkaline environment and a metal ion catalyst (detection solution). As a result, when galactose is sensed in the presence of H2O2, the colored response of the AuNS-PVP-GalDH assay transforms from turquoise blue to light pink, and then to wine red in a concentration-dependent manner discernible to the human eye. This competitive AuNS-PVP-GalDH assay could be a viable analytical tool for rapid and convenient galactose quantification in resource-limited areas.
摘要：
我们描述了一种竞争性比色测定法，可通过比色读数快速，灵敏地检测半乳糖和还原型烟酰胺腺嘌呤二核苷酸（NADH），并证明其对监测NAD驱动的酶促反应的有用性。我们提出了一种灵敏的等离子体感应方法，用于使用半乳糖脱氢酶固定的金纳米星（AuNS-PVP-GalDH）评估半乳糖浓度和NADH的存在。在不存在半乳糖和NADH的情况下，AuNS-PVP-GalDH测定仍然是绿松石蓝色；然而，随着半乳糖和NADH浓度的增长，在碱性环境和金属离子催化剂(检测溶液)的存在下,反应孔颜色变为特征性的红色。因此,当在H2O2存在下检测到半乳糖时，AuNS-PVP-GalDH测定的有色反应从绿松石蓝色转变为浅粉红色，然后以人眼可辨别的浓度依赖的方式变成酒红色。这种竞争性的AuNS-PVP-GalDH测定可能是在资源有限的地区快速便捷地定量半乳糖的可行分析工具。
