Kaur Mandeep, Bhattacharya Mily, Maity Banibrata
Department of Chemistry and Biochemistry, Thapar Institute of Engineering and Technology Patiala 147004 India
RSC Adv. 2025 Jun 11;15(25):19884-19898. doi: 10.1039/d5ra00824g. eCollection 2025 Jun 10.
4-Nitrophenol (4-NP) is a toxic, persistent, and carcinogenic pollutant, classified by the U.S. EPA as a primary contaminant. Commonly released by the pharmaceutical industry, it poses serious health risks, damaging the liver, kidneys, central nervous system, and bloodstream, highlighting the need for eco-friendly detection methods. To solve the difficulty of 4-NP detection, the work offers a unique and sustainable detection approach based on nitrogen and chlorine co-functionalized carbon quantum dots (S-CQDs). The hydrothermal approach was used for the synthesis, with sucrose serving as a carbon precursor and a deep eutectic solvent (DES) composed of urea and choline chloride in a 1 : 2 molar ratio. The nanosensor exhibited strong green fluorescence, excellent water solubility, photostability and ∼56%. Quantum yield. HRTEM revealed spherical and monodispersed S-CQDs that averaged 3.06 nm in size. FTIR and XPS investigations revealed amino, hydroxyl, carboxyl, and chlorine groups on the surface of S-CQDs, confirming intrinsic nitrogen and chlorine functionalization. XRD, UV-vis spectroscopy, fluorescence spectroscopy, and TCSPC were used for further characterization. For 4-nitrophenol (4-NP), the nanoprobe demonstrated excellent sensitivity and selectivity with a detection limit of 10 nM. An inner filter effect (IFE) associated with a zwitterionic spirocyclic Meisenheimer complex was confirmed by mechanistic investigations because of spectrum overlap and unaltered lifespan values. To further elucidate the sensing process, photophysical metrics like binding constants and quenching efficiency were also assessed. This work paves the way for developing a sensitive, green fluorescent nanosensor for a rapid, cost-effective and environmentally friendly approach as well as on-site detection of 4-NP, offering a promising tool for pollution monitoring and control for environmental water samples.
4-硝基苯酚（4-NP）是一种有毒、持久且致癌的污染物，被美国环境保护局列为主要污染物。它通常由制药行业排放，会带来严重的健康风险，损害肝脏、肾脏、中枢神经系统和血液，这凸显了对环保检测方法的需求。为了解决4-NP检测的难题，这项工作提供了一种基于氮和氯共功能化碳量子点（S-CQDs）的独特且可持续的检测方法。采用水热法进行合成，以蔗糖作为碳前驱体，以及由尿素和氯化胆碱按1:2摩尔比组成的深共熔溶剂（DES）。该纳米传感器呈现出强烈的绿色荧光、优异的水溶性、光稳定性以及约56%的量子产率。高分辨透射电子显微镜（HRTEM）显示S-CQDs呈球形且单分散，平均尺寸为3.06纳米。傅里叶变换红外光谱（FTIR）和X射线光电子能谱（XPS）研究揭示了S-CQDs表面存在氨基、羟基、羧基和氯基团，证实了其内在的氮和氯功能化。利用X射线衍射（XRD）、紫外可见光谱、荧光光谱和时间相关单光子计数（TCSPC）进行进一步表征。对于4-硝基苯酚（4-NP），该纳米探针表现出优异的灵敏度和选择性，检测限为10 nM。机理研究证实了与两性离子螺环迈森海默络合物相关的内滤效应（IFE），原因是光谱重叠且寿命值未改变。为了进一步阐明传感过程，还评估了诸如结合常数和猝灭效率等光物理指标。这项工作为开发一种用于快速、经济高效且环境友好的方法以及现场检测4-NP的灵敏绿色荧光纳米传感器铺平了道路，为环境水样的污染监测和控制提供了一种有前景的工具。
