A simple, sensitive, and fluorescent immunoassay for the detection of prostate-specific antigen (PSA) based on horseradish peroxidase and silicon dioxide nanospheres as a signal amplification strategy has been described. In the design, the primary antibody (Ab₁) of PSA was first immobilized on the 96-well plates via physical adsorption between polystyrene and hydrophobic groups of the antibody molecule. The silicon dioxide nanospheres (SiO₂ NSs), with large surface area and good biocompatibility, were loaded with horseradish peroxidase (HRP) and horseradish peroxidase-labeled secondary antibodies (HRP-Ab₂) as signal amplification systems. In the presence of PSA, a sandwich-type immunocomplex composed of Ab₁-Ag-HRP-Ab₂ had been formed. Fluorescence technology was employed to obtain the response signal of the immunoassay in the L-tyrosine and H₂O₂ systems. Experiment results showed that a strong and stable fluorescent signal at 416 nm (excitation wavelength: 325 nm) was observed, and the changes in fluorescent intensity were related to the levels of PSA. Under the optimal conditions, the relative fluorescence intensity was linear with the logarithm of PSA concentration from 0.03 to 100 ng·mL⁻¹, with a detection limit of 0.01 ng·mL⁻¹ (at a signal/noise ratio of 3). In contrast to other fluorescent immunoassays, the sandwich-type immunoreaction based on the high binding ELISA plates has the advantages of being simple, stable, and easy to operate, high selectivity, small sample quantity, etc., which can be widely used in the selective detection of a variety of targets, from DNA to proteins and small molecules. Such fluorescent immunoassays should be feasible for the fields of molecular diagnosis and other life science fields in the future.

中文翻译：

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基于辣根过氧化物酶和二氧化硅纳米球信号放大策略的前列腺特异性抗原检测的灵敏荧光免疫分析

已经描述了一种基于辣根过氧化物酶和二氧化硅纳米球作为信号放大策略检测前列腺特异性抗原 (PSA) 的简单、灵敏和荧光免疫测定法。在设计中，PSA的一抗（Ab ₁）首先通过聚苯乙烯和抗体分子的疏水基团之间的物理吸附固定在96孔板上。_{以辣根过氧化物酶（HRP）和辣根过氧化物酶标记的二抗（HRP-Ab 2}）作为信号放大系统的二氧化硅纳米球（SiO ₂ NSs）具有较大的表面积和良好的生物相容性。_{在 PSA 存在下，由 Ab 1} -Ag-HRP-Ab ₂组成的夹心型免疫复合物已经形成。采用荧光技术获得L-酪氨酸和H ₂ O ₂系统中免疫测定的反应信号。实验结果表明，在416 nm（激发波长：325 nm）处观察到强烈而稳定的荧光信号，荧光强度的变化与PSA水平有关。在最佳条件下，相对荧光强度在0.03～100 ng·mL ^-1范围内与PSA浓度的对数呈线性关系，检出限为0.01 ng·mL ^-1（信噪比为 3）。与其他荧光免疫分析相比，基于高结合ELISA板的夹心式免疫反应具有简单、稳定、易操作、选择性高、样本量小等优点，可广泛应用于选择性检测各种目标，从 DNA 到蛋白质和小分子。这种荧光免疫分析在未来的分子诊断和其他生命科学领域应该是可行的。