A target-induced tripedal G-quadruplex DNAzyme (TGD) for visual point-of-care testing (POCT) of PSA proteins by using solid Au nanorods (Au NRs)-decorated electrospun nanofibrous films was constructed. The TGD was formed by the recycling amplification cascades of target-triggered catalytic hairpin assembly (CHA), which exhibited superior horseradish peroxidase (HRP) mimicking activity to facilitate the degradation of H₂O₂ into hydroxyl radicals (·OH). The ·OH oxidized the 3,3′,5,5′-tetramethylbenzidine (TMB) into TMB⁺. Then, the TMB⁺ was converted into TMB²⁺ in the acidic environment, which can etch the Au NRs for further promoting the blue shift of their longitudinal surface plasmon resonance (LSPR) absorption peak. Thereby, with the increasing PSA concentrations, the proposed strategy presented palpable color variations from green, cyan, violet, and red by naked eyes. Significantly, the cutoff values near 4.0 and 10.0 ng/mL of PSA in human blood serum could be discriminated with naked eyes, which could provide a semi-quantitative process for the early diagnosis and prognosis evaluation. In addition, this portable, and label-free TDG biosensor exhibited remarkable improvements in sensitivity with a low detection limit of 61.1 fg/mL for PSA protein. This strategy showed the great versatility and potential for the visual biomedical detection with portable type and early diagnosis of diseases.

使用固体金纳米棒 (Au NRs) 装饰的电纺纳米纤维膜构建了一种用于 PSA 蛋白的视觉即时检测 (POCT) 的靶诱导三足 G-四链体脱氧核糖核酸酶 (TGD)。TGD由目标触发的催化发夹组装（CHA）的循环放大级联形成，其表现出优异的辣根过氧化物酶（HRP）模拟活性以促进H ₂ O ₂降解为羟基自由基（·OH）。·OH将3,3',5,5'-四甲基联苯胺(TMB)氧化成TMB ⁺。然后，将 TMB ⁺转换为 TMB ²⁺在酸性环境中，可以蚀刻Au NR，进一步促进其纵向表面等离子体共振（LSPR）吸收峰的蓝移。因此，随着 PSA 浓度的增加，所提出的策略呈现出肉眼可见的绿色、青色、紫色和红色的颜色变化。值得注意的是，人血清中PSA在4.0和10.0 ng/mL附近的临界值可以用肉眼区分，这可以为早期诊断和预后评估提供半定量的过程。此外，这种便携式、无标记的 TDG 生物传感器的灵敏度显着提高，PSA 蛋白的检测限低至 61.1 fg/mL。该策略显示了便携式视觉生物医学检测和疾病早期诊断的巨大通用性和潜力。