PDF(Pubmed)
Abstract：
The sensitivity of immunoassays is generally limited by the low signal reporter/recognition element ratio. Nanomaterials serving as the carriers can enhance the loading number of signal reporters, thus improving the detection sensitivity. However, the general immobilization strategies, including direct physical adsorption and covalent coupling, may cause the random orientation and conformational change in proteins, partially or completely suppressing the enzymatic activity and the molecular recognition ability. In this work, we proposed a strategy to load recognition elements of antibodies and enzyme labels using boronic acid-modified metal-organic frameworks (MOFs) as the nanocarriers for signal amplification. The conjugation strategy was proposed based on the boronate ester interactions between the carbohydrate moieties in antibodies and enzymes and the boronic acid moieties on MOFs. Both enzymes and MOFs could catalyze the oxidation of 3,3\',5,5\'-tetramethylbenzidine (TMB) by H2O2, therefore achieving dual signal amplification. To indicate the feasibility and sensitivity of the strategy, colorimetric immunoassays of prostate specific antigen (PSA) were performed with boronic acid-modified Cu-MOFs as peroxidase mimics to catalyze TMB oxidation and nanocarriers to load antibody and enzyme (horseradish peroxidase, HRP). According to the change in the absorbance intensity of the oxidized TMB (oxTMB), PSA at the concentration range of 1~250 pg/mL could be readily determined. In addition, this work presented a site-specific and oriented conjugation strategy for the modification of nanolabels with recognition elements and signal reporters, which should be valuable for the design of novel biosensors with high sensitivity and selectivity.
摘要：
免疫测定的灵敏度通常受到低信号报道分子/识别元件比率的限制。纳米材料作为载体可以提高信号报道分子的负载数量，从而提高检测灵敏度。然而,一般的固定策略，包括直接物理吸附和共价偶联，可能会导致蛋白质的随机取向和构象变化，部分或完全抑制酶活性和分子识别能力。在这项工作中,我们提出了一种策略,使用硼酸修饰的金属有机框架(MOFs)作为信号放大的纳米载体,加载抗体和酶标记的识别元件.缀合策略是基于抗体和酶中的碳水化合物部分与MOF上的硼酸部分之间的硼酸酯相互作用提出的。酶和MOFs都可以催化3,3'，5,5'-四甲基联苯胺(TMB)通过H2O2,因此实现双信号放大。为了表明战略的可行性和敏感性，用硼酸修饰的Cu-MOFs作为过氧化物酶模拟物催化TMB氧化，纳米载体加载抗体和酶（辣根过氧化物酶，HRP）。根据氧化的TMB（oxTMB）的吸光度强度的变化，在1~250μg/mL的浓度范围内的PSA可以容易地测定。此外,这项工作提出了一种位点特异性和定向的共轭策略，用于修饰具有识别元件和信号报告基因的纳米标签，这对于设计具有高灵敏度和选择性的新型生物传感器具有一定的参考价值。
