The study incorporates the urea detection in non-enzymatic urea samples and enzymatic urea-urease samples utilizing the phenomenon of surface plasmon resonance (SPR)/localized surface plasmon resonance (LSPR) realized on the core of a multimoded optical fiber. The designed bio-sensor, primarily a refractive index sensor well operates for the urea detection in the concentrations ranging 50–800 mM. The experimental results show that as urea concentration increases in both samples (non-enzymatic and enzymatic), refractive indices also increases leading to a red shift in the resonance wavelength (SPR wavelength). Further, the sensing probe was modified by coating biosynthesized gold nanoparticles (AuNPs) on to the thin layer of gold (Au) by dipping the probe in the solution of biosynthesized AuNPs. After performing the experiments, the sensitivity values were calculated for solutions of different concentration of urea in non-enzymatic and enzymatic urea samples and compared with the probes coated with Au film only. A comparative study of the two set of results reveals a two-fold and three-fold enhancement in the sensitivity values for non-enzymatic and enzymatic urea samples respectively as compared with the probe without AuNPs. Authors believe that the present fiber optic bio sensing probe is easy to design, low cost, capable of remote sensing. Also it works well in the range near to the pathophysiological range of urea in human blood and hence can be beneficial for the determination of urea concentration in medical diagnostics as well.

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使用生物合成金纳米粒子检测尿素：在光纤上实现的基于 SPR/LSPR 的传感方法

该研究利用在多模光纤核心上实现的表面等离子体共振 (SPR)/局域表面等离子体共振 (LSPR) 现象，在非酶促尿素样品和酶促尿素酶样品中进行尿素检测。设计的生物传感器，主要是折射率传感器，适用于浓度范围为 50-800 mM 的尿素检测。实验结果表明，随着两个样品（非酶促和酶促）中尿素浓度的增加，折射率也增加，导致共振波长（SPR 波长）发生红移。此外，通过将探针浸入生物合成的 AuNPs 溶液中，将生物合成的金纳米粒子 (AuNPs) 涂覆到金 (Au) 薄层上，从而对传感探针进行了修饰。进行实验后，计算了非酶促和酶促尿素样品中不同浓度尿素溶液的灵敏度值，并与仅涂有金膜的探针进行了比较。两组结果的比较研究表明，与不含 AuNP 的探针相比，非酶促和酶促尿素样品的灵敏度值分别提高了两倍和三倍。作者认为，目前的光纤生物传感探头设计简单，成本低，可实现遥感。此外，它在接近人体血液中尿素病理生理范围的范围内工作良好，因此也有利于医学诊断中尿素浓度的测定。