Departamento de Quimica Fisica, Universidade de Vigo, 36310 Vigo, Spain.
Nat Mater. 2012 May 27;11(7):604-7. doi: 10.1038/nmat3337.
Lowering the limit of detection is key to the design of sensors needed for food safety regulations, environmental policies and the diagnosis of severe diseases. However, because conventional transducers generate a signal that is directly proportional to the concentration of the target molecule, ultralow concentrations of the molecule result in variations in the physical properties of the sensor that are tiny, and therefore difficult to detect with confidence. Here we present a signal-generation mechanism that redefines the limit of detection of nanoparticle sensors by inducing a signal that is larger when the target molecule is less concentrated. The key step to achieve this inverse sensitivity is to use an enzyme that controls the rate of nucleation of silver nanocrystals on plasmonic transducers. We demonstrate the outstanding sensitivity and robustness of this approach by detecting the cancer biomarker prostate-specific antigen down to 10(-18) g ml(-1) (4 × 10(-20) M) in whole serum.
降低检测极限是食品安全法规、环境政策和严重疾病诊断所需传感器设计的关键。然而，由于传统传感器产生的信号与目标分子的浓度成正比，因此分子的超低浓度会导致传感器的物理性质发生微小变化，从而难以自信地检测到。在这里，我们提出了一种信号产生机制，通过诱导目标分子浓度较低时信号更大，从而重新定义了纳米颗粒传感器的检测极限。实现这种反灵敏度的关键步骤是使用一种酶来控制银纳米晶体在等离子体传感器上成核的速率。我们通过在全血清中检测到前列腺特异性抗原（前列腺癌的生物标志物）低至 10(-18) g ml(-1)（4 × 10(-20) M），证明了这种方法的出色灵敏度和稳健性。
