The ascorbic acid (AA) is a biomarker that can be used to detect the symptoms of severe disorders such as scurvy, Parkinson’s, Alzheimer’s, and cardiovascular diseases. In this work, a simple and effective sensor model is developed to diagnose the presence of AA samples. To develop the sensor, a tapered single-mode optical fiber has been used with the well-known phenomenon of localized surface plasmon resonance (LSPR). For LSPR, the tapered region is immobilized with synthesized gold nanoparticles (AuNPs) and zinc oxide nanoparticles (ZnO-NPs) whose absorbance peak wavelengths appear at 519nm and 370nm, respectively. On the basis of nanoparticles (NPs) configurations, two different biosensor probes are developed. In the first one, the sensing region is immobilized with AuNPs and named Probe I. In the second probe, the immobilized layer of AuNPs is further coated with a layer of ZnO-NPs, and a resultant probe is termed as Probe II. The characterizations of synthesized AuNPs and developed fiber probes are done by the ultraviolet-visible (UV-vis) spectrophotometer, high-resolution transmission electron microscope (HR-TEM), atomic force microscopy (AFM), and scanning electron microscope (SEM). To enhance the selectivity, a sensing region of probes is functionalized with ascorbate oxidase enzyme that oxidizes the AA in the presence of oxygen. The response of developed sensor probes is authenticated by sensing the samples of AA in the range from 500 nM to 1 mM, which covers the range of AA found in human bodies, i.e., 40µM–120µM. The performance analysis of the developed sensor probes has been done in terms of their stability, reproducibility, reusability, and selectivity. To observe the stability of AA, a pH-test has also been done that results in a better solubility of AA molecules in phosphate-buffered saline (PBS) solution.

抗坏血酸（AA）是一种生物标记，可用于检测严重疾病的症状，例如坏血病，帕金森氏症，阿尔茨海默氏症和心血管疾病。在这项工作中，开发了一种简单有效的传感器模型来诊断AA样品的存在。为了开发传感器，已经使用了锥形单模光纤以及众所周知的局部表面等离振子共振（LSPR）现象。对于LSPR，锥形区固定有吸收峰波长分别在519nm和370nm处出现的合成金纳米颗粒（AuNPs）和氧化锌纳米颗粒（ZnO-NPs）。基于纳米粒子（NPs）的配置，开发了两种不同的生物传感器探针。在第一个探针中，传感区域固定有AuNP，并命名为ProbeI。在第二个探针中，将固定的AuNPs层进一步涂覆一层ZnO-NPs，并将所得的探针称为探针II。合成的AuNPs和开发的纤维探针的表征是通过紫外可见（UV-vis）分光光度计，高分辨率透射电子显微镜（HR-TEM），原子力显微镜（AFM）和扫描电子显微镜（SEM）进行的。为了提高选择性，探针的感应区域用抗坏血酸氧化酶功能化，该酶在氧气存在下将AA氧化。通过检测500 nM至1 mM范围内的AA样品，可以验证开发的传感器探针的响应，该范围涵盖了人体中发现的AA范围，即40µM–120µM。已对传感器探头的稳定性，可重复性，可重复使用性，和选择性。为了观察AA的稳定性，还进行了pH测试，使AA分子在磷酸盐缓冲盐水（PBS）溶液中具有更好的溶解度。