L-lactate is an essential organic chemical in food processing, clinical, chemical, and fermentation industries. AuNPs were synthesized by chemical reduction reaction method and functionalized with 3-aminophenylboronic acid (3-APBA). The structural, morphological, FTIR, DLS, zeta potential characterization studies were performed to optimize the sensing mechanism. First time reporting facile enzyme-free sensor for the detection of L-lactate content in milk. Initially, the sensor has been optimized for nano reagent concentration, pH and time. 3-APBA@AuNPs showed a stable SPR intensity and forms a reversible tetrahedral ester complex with the analyte L-lactate (100 mM) resulting the NPs aggregation and revealing the blue shift of UV-VIS absorption wavelength (λ = 300 nm to 288 nm). Nestle- Lactogen, an India commercial milk powder has been used for the standardization study of lactate sensing. The milk samples spiked with L-Lactate (1-20mM) showed an increase in UV-VIS absorption peak intensity with concentration, and estimated the lower detection limit (LOD) = 1.1 mM using the calibration graphs. The optical sensing mechanism is explained may be due to π-π* transition of AuNPs stabilized by tetragonal complex of L-lactate bonded to 3-boronate via nucleophilic attack on boron atom. The nanosensor data was validated with commercial Megazyme kit and conventional HPLC technique. In commercial product Amul-India milk, the L-lactate value estimated as 0.678Mm with 95% correlation. Hence, the proposed sensor technique could be an alternate to the high cost conventional methods and at next level, it can be interfaced to smart phone to develop an onsite food, pharma and clinical device applications.

中文翻译：

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基于 AuNP 的高选择性和无标记光学传感器的开发对于智能手机传感食品样品中的 L-乳酸具有重要意义


L-乳酸是食品加工、临床、化学和发酵工业中重要的有机化学品。通过化学还原反应方法合成了AuNPs，并用3-氨基苯硼酸（3-APBA）进行功能化。进行结构、形态、FTIR、DLS、zeta 电位表征研究以优化传感机制。首次报道用于检测牛奶中L-乳酸含量的简易无酶传感器。最初，传感器已针对纳米试剂浓度、pH 值和时间进行了优化。 3-APBA@AuNPs 显示出稳定的 SPR 强度，并与分析物 L-乳酸 (100 mM) 形成可逆的四面体酯复合物，导致 NP 聚集，并显示 UV-VIS 吸收波长的蓝移（λ = 300 nm 至 288 nm） ）。印度商业奶粉雀巢Lactogen已被用于乳酸传感的标准化研究。添加 L-乳酸 (1-20mM) 的牛奶样品显示 UV-VIS 吸收峰强度随浓度的增加而增加，并使用校准图估计检测下限 (LOD) = 1.1 mM。光学传感机制被解释为可能是由于通过对硼原子的亲核攻击，L-乳酸盐与3-硼酸盐键合的四方复合物稳定了AuNPs的π-π*转变。纳米传感器数据通过商业 Megazyme 试剂盒和传统 HPLC 技术进行验证。在商业产品 Amul-India 牛奶中，L-乳酸值估计为 0.678Mm，相关性为 95%。因此，所提出的传感器技术可以替代高成本的传统方法，并且在下一个层面上，它可以与智能手机连接以开发现场食品、制药和临床设备应用。