This comprehensive study is related to gold nanoparticles (GNPs) conjugated with antibodies. The goal of the study is to determine the minimal concentration of antibodies for conjugate synthesis when the conjugates have high antigen-capturing activity. Two systems were studied: gold nanoparticles conjugated with monoclonal antibodies (mAb-GNP) specific to Helicobacter pylori and gold nanoparticles conjugated with polyclonal antibodies (pAb-GNP) specific to mouse immunoglobulins. Several conjugates were synthesized with different GNP-to-antibody molar ratios (from 1:1 to 1:245) through nondirectional and noncovalent immobilization on a surface of GNPs with a diameter of 25.3 ± 4.6 nm. The maximal antigen-capturing activities and equilibrium constants of the conjugates correlate with the formation of a constant hydrodynamic radius of the conjugates for mAb-GNP (GNP to antibody molar ratio 1:58) and with the stabilizing concentration by flocculation curves for pAb-GNP (GNP to antibody molar ratio 1:116). The application of the conjugates to the lateral flow immunoassay shows that the antibody concentrations used for the conjugation can be reduced (below the stabilizing concentration) without losing activity for the mAb-GNP conjugates. The findings highlight that the optimal concentration of antibodies immobilized on the surface of GNPs is not always equal to the stabilizing concentration determined by the flocculation curve.

中文翻译：

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少即是多：不同比例的抗体-金纳米颗粒共轭物的比较

这项全面的研究涉及与抗体偶联的金纳米颗粒（GNP）。该研究的目的是确定当缀合物具有高抗原捕获活性时用于缀合物合成的抗体的最小浓度。研究了两个系统：金纳米颗粒与幽门螺杆菌特异的单克隆抗体（mAb-GNP）偶联以及与小鼠免疫球蛋白特异的多克隆抗体（pAb-GNP）偶联的金纳米颗粒。通过非定向和非共价固定在直径25.3±4.6 nm的GNP表面上，合成了几种具有不同GNP与抗体摩尔比（从1：1到1：245）的结合物。结合物的最大抗原捕获活性和平衡常数与mAb-GNP结合物的恒定流体动力学半径的形成（GNP与抗体的摩尔比为1:58）以及pAb-GNP的絮凝曲线稳定浓度有关（GNP与抗体的摩尔比为1:16）。缀合物在侧向流免疫测定中的应用表明，可以降低用于缀合的抗体浓度（低于稳定浓度），而不会失去对mAb-GNP缀合物的活性。研究结果表明，固定在GNP表面的抗体的最佳浓度并不总是等于絮凝曲线确定的稳定浓度。