HKUST-1 MOFs and its derivative HKUST-CuO were coupled with TiO₂ nanoparticles to form the heterogeneous composites of HKUST-1/TiO₂ and HKUST-CuO/TiO₂ based on their well-suitable bandgap energies (Eg). Compared with mono-component HKUST-1 or HKUST-CuO, the prepared composites displayed photoelectrochemical (PEC) response due to the synergistic effect from their heterogeneous structure. Higher photocurrent response was obtained on HKUST-CuO/TiO₂-modified ITO electrode (HKUST-CuO/TiO₂/ITO), which could be attributed to the hollow structure with a thin shell of HKUST-CuO greatly enhancing visible spectra harvesting. The CuO component in HKUST-CuO not only could accelerate electron transfer on the heterojunction interface but also effectively separate the photo-generated charge carriers (e⁻¹/h⁺). Based on the excellent PEC performance of prepared photoactive composite material, under visible-light excitation (λ ≥ 420 nm) and with a working potential of 0 V (vs. Ag/AgCl), the S1 (probe DNA)/HKUST-CuO/TiO₂/ITO PEC platform was successfully fabricated for colitoxin DNA detection without using ascorbic acid (AA) as an electron donor. Compared with the analysis results on S1/HKUST-1/TiO₂/ITO electrode, S1/HKUST-CuO/TiO₂/ITO displayed a wider linear response range from 1.0 × 10⁻⁶ to 4.0 × 10⁻¹ nM with a lower detection limit of 3.73 × 10⁻⁷ nM (S/N = 3), the linear regression equation was ΔI (10⁻⁶ A) =0.5549–0.1858 log (C_S2/M), which confirmed the HKUST-CuO could improve sensitivity because of its prominent PEC property. The relative standard deviation (RSD) of the PEC sensor for target DNA detection of 2.0 × 10⁻⁴ nM was 7.4%. The proposed DNA biosensor also possessed good specificity and stability. Hence, this reported work was a promising strategy for molecular diagnosis in the bio-analysis field.

Graphical abstract

中文翻译：

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基于 HKUST-1/TiO2 和衍生的 HKUST-CuO/TiO2 异质复合材料的大肠杆菌毒素 DNA 的增强型光电化学生物传感器

HKUST-1 MOFs 及其衍生物 HKUST-CuO 与 TiO ₂纳米颗粒结合形成 HKUST-1/TiO ₂和 HKUST-CuO/TiO ₂的非均相复合材料，基于它们非常合适的带隙能量（Eg）。与单组分 HKUST-1 或 HKUST-CuO 相比，所制备的复合材料由于其异质结构的协同效应而表现出光电化学 (PEC) 响应。在 HKUST-CuO/TiO ₂修饰的 ITO 电极 (HKUST-CuO/TiO ₂/ITO），这可归因于具有 HKUST-CuO 薄壳的空心结构，极大地增强了可见光谱的采集。HKUST-CuO中的CuO组分不仅可以加速异质结界面上的电子转移，还可以有效分离光生电荷载流子（e ^-1 /h ⁺）。基于所制备的光敏复合材料优异的 PEC 性能，在可见光激发（λ  ≥ 420 nm）和 0 V 的工作电位（vs. Ag/AgCl）下，S1（探针 DNA）/HKUST-CuO/在不使用抗坏血酸 (AA) 作为电子供体的情况下，成功制造了TiO _{2 /ITO PEC 平台用于大肠杆菌毒素 DNA 检测。}与 S1/HKUST-1/TiO _{2的分析结果比较}/ITO 电极，S1/HKUST-CuO/TiO ₂ /ITO 显示出更宽的线性响应范围，从 1.0 × 10 ^-6到 4.0 × 10 ^-1  nM，检测下限为 3.73 × 10 ^-7  nM (S/ N  = 3)，线性回归方程为Δ I (10 ^-6 A) =0.5549–0.1858 log ( C _S2 /M)，这证实了HKUST-CuO由于其突出的PEC特性可以提高灵敏度。用于目标 DNA 检测的 PEC 传感器的相对标准偏差 (RSD) 为 2.0 × 10 ^-4 nM 为 7.4%。所提出的DNA生物传感器还具有良好的特异性和稳定性。因此，这项报告的工作是生物分析领域分子诊断的有前途的策略。

图形概要