Ascorbic acid (AA) detection in biological sample and food sample is critical for human health. Herein, a MnO₂ nanosheet (MnO₂-NS)-based ratiometric fluorescent nanosensor has been developed for high sensitive and specific detection of AA. The MnO₂-NS presents peroxidase-like activity and can oxidize non-fluorescent substrate of o-phenylenediamine (OPDA) into fluorescent substrate, presenting maximum fluorescence at 568 nm (F₅₆₈). If MnO₂-NS is premixed with AA, the MnO₂-NS is then decomposed as Mn²⁺ by AA, decreasing the fluorescent intensity of F₅₆₈. Meantime, AA is oxidized as dehydroascorbic acid (DHAA), which can react with OPDA to generate fluorescent substrate. A new fluorescence response is found at 425 nm (F₄₂₅). The dual fluorescent responses can be excited with a universal excitation wavelength, simplifying the detection procedure. With F₄₂₅/F₅₆₈ as readout, limit of detection for AA reaches as low as 10.0 nM. Satisfactory recoveries are found for AA detection in serum and diverse beverages. The ratiometric strategy significantly eliminates false-negative and false-positive results, providing a cost-effective, rapid, and reliable way for AA detection in real sample.

生物样品和食品样品中抗坏血酸（AA）的检测对人体健康至关重要。在本文中，已经开发了基于MnO ₂纳米片（MnO ₂ -NS）的比例荧光纳米传感器，用于AA的高灵敏度和特异性检测。MnO ₂ -NS表现出类似过氧化物酶的活性，并且可以将邻苯二胺（OPDA）的非荧光底物氧化为荧光底物，从而在568 nm（F ₅₆₈）处呈现最大荧光。如果将MnO ₂ -NS与AA预混合，则MnO ₂ -NS会被AA分解为Mn ²⁺，从而降低F ₅₆₈的荧光强度。同时，AA被氧化为脱氢抗坏血酸（DHAA），可以与OPDA反应生成荧光底物。在425 nm（F ₄₂₅）处发现了新的荧光响应。可以用通用的激发波长来激发双重荧光响应，从而简化了检测程序。使用F ₄₂₅ / F ₅₆₈作为读数，AA的检测限可低至10.0 nM。发现血清和各种饮料中的AA检测均具有令人满意的回收率。比率测量策略可显着消除假阴性和假阳性结果，为实际样品中的AA检测提供了一种经济高效，快速而可靠的方法。