Chitosan (CS) is a natural polymer widely used in many fields. However, there are seldom studies that focus on its inherent fluorescence properties. In this work, based on the inherent fluorescence of chitosan (CS) and the mechanism that it can be quenched by hexavalent chromium (Cr(VI)), we developed novel CS-based inverse opal particles (IOPs) for Cr(VI) detection. The CS IOPs were obtained by replicating the silica colloidal crystal beads using CS, which displayed uniform shape and size, as well as enhanced fluorescence-emission capability resulted from the unique microstructure. Under the optimized conditions, the CS IOPs responded to Cr(VI) in a range of 0–10,000 μM with high sensitivity and specificity and demonstrated a LOD of 0.055 μM at the linear range of 0–30 μM. Furthermore, they displayed good detection ability in practical applications with recoveries of 86–106% for tap water and 99.7–107.3% for pond water, respectively. With these features, the developed CS IOPs are promising to be a simple, low-cost, and fast platform for detecting Cr(VI).

壳聚糖（CS）是一种广泛应用于许多领域的天然聚合物。然而，很少有研究关注其固有的荧光特性。在这项工作中，基于壳聚糖（CS）固有的荧光及其可以被六价铬（Cr（VI））猝灭的机制，我们开发了新型基于CS的反蛋白石颗粒（IOP）用于Cr（VI）检测。CS IOP是通过使用CS复制二氧化硅胶体晶体珠而获得的，其具有均匀的形状和尺寸，以及由于独特的微观结构而增强的荧光发射能力。在优化条件下，CS IOP 在 0–10,000 μM 范围内对 Cr(VI) 具有高灵敏度和特异性，并在 0–30 μM 线性范围内表现出 0.055 μM 的 LOD。此外，它们在实际应用中表现出良好的检测能力，自来水和池塘水的回收率分别为 86-106% 和 99.7-107.3%。凭借这些特性，所开发的 CS IOP 有望成为一种简单、低成本、快速的 Cr(VI) 检测平台。