Optimizing linear polymer affinity agent properties for surface-enhanced Raman scattering detection of aflatoxin B1
Optimizing linear polymer affinity agent properties for surface-enhanced Raman scattering detection of aflatoxin B1
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DOI：
10.1039/c9me00032a
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发表时间：
2019-10-01
影响因子：
3.6
通讯作者：
Reineke, Theresa M.
中科院分区：
文献类型：
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作者：
Szlag, Victoria M.;Rodriguez, Rebeca S.;Reineke, Theresa M.
合成了一系列聚（N-丙烯酰甘氨酰胺）（pNAGA）聚合物，并研究了其作为表面增强拉曼散射（Sers）捕获剂对高致癌性食源性毒素黄曲霉毒素B1（AFB 1）的检测。通过可逆加成-断裂链转移（RAFT）聚合法合成了4种分子量的pNAGA，以研究AFB 1传感平台的亲和剂效力对链长的依赖性。等温滴定量热法（ITC）用于验证溶液中聚合物-黄曲霉毒素B1相互作用所涉及的疏水效应的符号和大小，并了解pNAGA链长对黄曲霉毒素B1非共价结合的影响。发现pNAGA-AFB 1相互作用是放热的，并且较长的pNAGA链通常导致每个重复单元的焓降低较小。由于pNAGA（22）是最强的亲合力剂，我们假设AFB 1的亲合力是由pNAGA链的构型限制和结合AFB 1的亲合力优势之间的平衡决定的。使用AFB 1暴露后观察到的Sers光谱变化来评价聚合物分子量（2.0-5.2 kDa）、连接顺序（底物功能化前与后）和连接化学（硫醇与三硫代碳酸酯）对AFB 1检测灵敏度的影响。发现靶点、聚合物亲和剂和信号转导机制相结合的方法对所实现的灵敏度具有显著影响。最有效的聚合物链长（pNAGA（22））、锚定化学（硫醇）和聚合物/毒素组装方案（溶液中）允许在水中检测10 ppb的AFB 1（低于20 ppb的FDA监管限度），比没有pNAGA亲和剂的Sers传感提高了100倍。
A series of poly(N-acryloyl glycinamide) (pNAGA) polymers were synthesized and studied as capture agents for surface-enhanced Raman scattering (SERS) detection of aflatoxin B1 (AFB1), a highly carcinogenic food-borne toxin. Four molecular weights of pNAGA were synthesized by reversible addition-fragmentation chain-transfer (RAFT) polymerization to study the dependence of affinity agent efficacy on chain length for this AFB1 sensing platform. Isothermal titration calorimetry (ITC) was used to verify the sign and magnitude of the enthalpic effects involved in polymer-AFB1 interactions in solution and to understand the effects of pNAGA chain length on AFB1 noncovalent binding. pNAGA-AFB1 interactions were found to be exothermic, and longer pNAGA chains generally resulted in smaller enthalpy decreases per repeat unit. With pNAGA(22) being thermodynamically the strongest affinity agent, we hypothesize that AFB1 affinity is determined by a balance between the configurational restrictions in pNAGA chains and the enthalpic advantage of binding AFB1. SERS spectral changes observed following AFB1 exposure were used to evaluate the influence of polymer molecular weight (2.0-5.2 kDa), order of attachment (pre- vs. post- functionalization of the substrate) and attachment chemistry (thiol vs. trithiocarbonate) on the sensitivity of AFB1 detection. The method by which target, polymer affinity agent, and signal transduction mechanism are combined was found to have significant impacts on the achieved sensitivity. The most effective polymer chain length (pNAGA(22)), anchoring chemistry (thiol), and polymer/toxin assembly scheme (in-solution) allowed detection of 10 ppb AFB1 in water (below the FDA regulatory limit of 20 ppb), a hundred-fold improvement over SERS sensing without the pNAGA affinity agent.