Moldovan Rebeca, Iacob Bogdan-Cezar, Farcău Cosmin, Bodoki Ede, Oprean Radu
Analytical Chemistry Department, Faculty of Pharmacy, Iuliu Hațieganu University of Medicine and Pharmacy, 400349 Cluj-Napoca, Romania.
National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat, 400293 Cluj-Napoca, Romania.
Nanomaterials (Basel). 2021 Jan 25;11(2):304. doi: 10.3390/nano11020304.
Organochlorine pesticides (OCPs) embody highly lipophilic hazardous chemicals that are being phased out globally. Due to their persistent nature, they are still contaminating the environment, being classified as persistent organic pollutants (POPs). They bioaccumulate through bioconcentration and biomagnification, leading to elevated concentrations at higher trophic levels. Studies show that human long-term exposure to OCPs is correlated with a large panel of common chronic diseases. Due to toxicity concerns, most OCPs are listed as persistent organic pollutants (POPs). Conventionally, separation techniques such as gas chromatography are used to analyze OCPs (e.g., gas chromatography coupled with mass spectrometry (GC/MS)) or electron capture detection (GC/ECD). These are accurate, but expensive and time-consuming methods, which can only be performed in centralized lab environments after extensive pretreatment of the collected samples. Thus, researchers are continuously fueling the need to pursue new faster and less expensive alternatives for their detection and quantification that can be used in the field, possibly in miniaturized lab-on-a-chip systems. In this context, surface enhanced Raman spectroscopy (SERS) represents an exceptional analytical tool for the trace detection of pollutants, offering molecular fingerprint-type data and high sensitivity. For maximum signal amplification, two conditions are imposed: an efficient substrate and a high affinity toward the analyte. Unfortunately, due to the highly hydrophobic nature of these pollutants (OCPs,) they usually have a low affinity toward SERS substrates, increasing the challenge in their SERS detection. In order to overcome this limitation and take advantage of on-site Raman analysis of pollutants, researchers are devising ingenious strategies that are synthetically discussed in this review paper. Aiming to maximize the weak Raman signal of organochlorine pesticides, current practices of increasing the substrate's performance, along with efforts in improving the selectivity by SERS substrate functionalization meant to adsorb the OCPs in close proximity (via covalent, electrostatic or hydrophobic bonds), are both discussed. Moreover, the prospects of multiplex analysis are also approached. Finally, other perspectives for capturing such hydrophobic molecules (MIPs-molecularly imprinted polymers, immunoassays) and SERS coupled techniques (microfluidics-SERS, electrochemistry-SERS) to overcome some of the restraints are presented.
有机氯农药（OCPs）是一类高亲脂性的有害化学物质，目前正在全球范围内逐步淘汰。由于其持久性，它们仍在污染环境，被归类为持久性有机污染物（POPs）。它们通过生物浓缩和生物放大作用进行生物累积，导致在较高营养级水平上浓度升高。研究表明，人类长期接触有机氯农药与一系列常见慢性病有关。出于对毒性的担忧，大多数有机氯农药被列为持久性有机污染物（POPs）。传统上，使用气相色谱等分离技术来分析有机氯农药（例如，气相色谱与质谱联用（GC/MS））或电子捕获检测（GC/ECD）。这些方法准确，但昂贵且耗时，并且只能在对收集的样品进行广泛预处理后在集中式实验室环境中进行。因此，研究人员不断推动寻求新的更快、更便宜的替代方法来进行它们的检测和定量，这些方法可以在现场使用，可能在微型芯片实验室系统中。在这种背景下，表面增强拉曼光谱（SERS）是一种用于痕量检测污染物的卓越分析工具，可提供分子指纹类型的数据和高灵敏度。为了实现最大信号放大，需要满足两个条件：高效的基底和对分析物的高亲和力。不幸的是，由于这些污染物（有机氯农药）具有高度疏水性，它们通常对SERS基底的亲和力较低，这增加了它们的SERS检测难度。为了克服这一限制并利用对污染物的现场拉曼分析，研究人员正在设计巧妙的策略，本文将对这些策略进行综合讨论。为了使有机氯农药微弱的拉曼信号最大化，本文讨论了提高基底性能的当前做法，以及通过SERS基底功能化提高选择性的努力，旨在通过共价、静电或疏水键使有机氯农药紧密吸附。此外，还探讨了多重分析的前景。最后，介绍了捕获此类疏水分子的其他方法（分子印迹聚合物 - MIPs、免疫分析）以及SERS联用技术（微流控 - SERS、电化学 - SERS）以克服一些限制。
