Fluorescence detection is actually available on measuring substances by using metal-based micro or nano structures which produce a great surface enhanced fluorescence (SEF) effect in quick response to endless diseases and environmental problems recently. However, traditional SEF substrates are expensive, as well as inefficient due to single-component detection mode. Therefore, SEF substrates with controllable fluorescence enhancement formed by magnetically responsive CoFe₂O₄@SiO₂@Ag colloidal photonic crystals were designed in this work. The fluorescence spectra were enhanced selectively at different wavelength owing to photonic band gap adjusted by magnetic field so as to detect Rhodamine B (RB) and fluorescein isothiocyanate (FITC) which had quite different fluorescence emission wavelength. As-prepared composites showed that the highest enhancement factors were 12.6 and 17.6 fold for RB and FITC, respectively, only when the tunable photonic band gap matched with the fluorescence emission wavelength of fluorescent molecules. The mechanism of significant fluorescence enhancement was explained in detail. The CoFe₂O₄@SiO₂@Ag substrates were confirmed to be reliable, sensitive and reproducible in detecting a variety of fluorescent molecules. The results played an important role in effective fluorescence detection, such as chemical analysis, biological sensing and cell imaging.

荧光检测实际上是通过使用基于金属的微纳米结构来测量物质的，这些结构会产生很大的表面增强荧光（SEF）效应，以快速响应最近不断出现的疾病和环境问题。然而，传统的 SEF 基板价格昂贵，并且由于单组分检测模式而效率低下。因此，由磁响应 CoFe ₂ O ₄ @SiO ₂形成的具有可控荧光增强的 SEF 衬底在这项工作中设计了@Ag 胶体光子晶体。由于磁场调节光子带隙，荧光光谱在不同波长下选择性增强，从而检测出荧光发射波长差异较大的罗丹明B（RB）和异硫氰酸荧光素（FITC）。制备的复合材料表明，仅当可调光子带隙与荧光分子的荧光发射波长匹配时，RB 和 FITC 的最高增强因子分别为 12.6 和 17.6 倍。详细解释了显着荧光增强的机制。CoFe ₂ O ₄ @SiO ₂@Ag 底物被证实在检测各种荧光分子时是可靠、灵敏和可重复的。该结果在化学分析、生物传感和细胞成像等有效荧光检测中发挥了重要作用。