Abstract：
Fish epidermal mucus is an important reservoir of antipathogenic compounds which serves as the first line of the immune defence. Despite its significant role in the physiology and health of fish, detailed profiling of fish epidermal mucus has yet to be explored. Therefore, this study investigates a label-free colloidal surface-enhanced Raman spectroscopic (SERS) method for profiling grouper mucus. Gold nanoparticles were first synthesised using the standard citrate reduction and characterised using ultraviolet-visible spectroscopy, transmission electron microscopy and dynamic light scattering. The influence of acidified sodium sulphate (Na2SO4) at pH 3 as the aggregating agent on the enhancement of the SERS spectrum of different analyte samples including rhodamine 6G (R6G) dye, lysozyme solution and hybrid grouper (Epinephelus fuscoguttatus × Epinephelus lanceolatus) mucus was observed. Based on the results, an optimal Na2SO4 concentration of 1 M was recorded to achieve the highest enhancement of the SERS signal for R6G and grouper mucus, while the optimal concentration for lysozyme was 0.1 M. The results indicated a higher degree of aggregation induced by lysozyme than R6G and grouper mucus. A few overlapping peaks of the SERS spectra of lysozyme and grouper mucus made it possible to confirm the presence of lysozyme as potential biomarkers.
摘要：
鱼表皮粘液是抗病化合物的重要储库，可作为免疫防御的第一线。尽管它在鱼类的生理和健康中发挥了重要作用，鱼表皮粘液的详细轮廓还有待探索。因此,这项研究调查了一种无标记的胶体表面增强拉曼光谱（SERS）方法，用于分析石斑鱼粘液。首先使用标准柠檬酸盐还原法合成金纳米颗粒，并使用紫外-可见光谱进行表征，透射电子显微镜和动态光散射。pH3酸化硫酸钠（Na2SO4）作为聚集剂对包括罗丹明6G（R6G）染料在内的不同分析物样品的SERS光谱增强的影响，观察到溶菌酶溶液和杂种石斑鱼（Epinephelusfuscoguttatus×Epinepheluslanceolatus）粘液。根据结果,1M的最佳Na2SO4浓度被记录，以实现R6G和石斑鱼粘液的SERS信号的最高增强，而溶菌酶的最佳浓度为0.1M。结果表明，溶菌酶诱导的聚集程度高于R6G和石斑鱼粘液。溶菌酶和石斑鱼粘液的SERS光谱的一些重叠峰使得有可能确认溶菌酶作为潜在生物标志物的存在。
