Instituto de Carboquimica, CSIC, Miguel Luesma, 4 Zaragoza, Spain.
ACS Nano. 2010 Mar 23;4(3):1473-80. doi: 10.1021/nn901547b.
A proof of concept of the electronic detection of two anabolic steroids, stanozolol (Stz) and methylboldenone (MB), was carried out using two specific antibodies and arrays of carbon nanotube field-effect transistors (CNTFETs). Antibodies specific for Stz and MB were prepared and immobilized on the carbon nanotubes (CNTs) using two different approaches: direct noncovalent bonding of antibodies to the devices and bonding the antibodies covalently to a polymer previously attached to the CNTFETs. The results indicated that CNTFETs bonded to specific antibodies covalently or noncovalently are able to detect the presence of steroids. Statistically significant changes in the threshold voltage and drain current were registered in the transistors, allowing the steroids to be recognized. On the other hand, it was determined that the specific antibodies do not detect other steroids other than Stz and MB, such as nandrolone (ND) because, in this case, statistically significant changes in the transistors were not detected. The polymer prevents the aggregation of antibodies on the electrodes and decreases the transistor hysteresis. Nevertheless, it is not able to avoid the nonspecific adsorption of streptavidin, meaning that nonspecific adsorption on CNTs remains a problem and that this methodology is only useful for purified samples. Regarding the detection mechanism, in addition to charge transfer, Schottky barrier, SB, modification, and scattering potential reported by other authors, an electron/hole trapping mechanism leading to hysteresis modification has been determined. The presence of polymer seems to hinder the modulation of the electrode-CNT contact.
采用两种特定的抗体和碳纳米管场效应晶体管（CNTFET）阵列，对两种合成代谢类固醇，司坦唑醇（Stz）和甲基勃龙（MB）的电子检测进行了概念验证。制备了针对 Stz 和 MB 的特异性抗体，并通过两种不同的方法将其固定在碳纳米管（CNTs）上：抗体与器件的非共价直接键合，以及将抗体共价键合到先前连接到 CNTFET 上的聚合物上。结果表明，共价或非共价键合到特定抗体的 CNTFET 能够检测类固醇的存在。在晶体管中记录到了阈值电压和漏极电流的统计学上显著变化，从而可以识别类固醇。另一方面，确定特异性抗体不会检测到除 Stz 和 MB 以外的其他类固醇，例如去甲雄酮（ND），因为在这种情况下，未检测到晶体管的统计学上显著变化。聚合物可防止抗体在电极上聚集并减少晶体管滞后。尽管如此，它并不能避免链霉亲和素的非特异性吸附，这意味着非特异性吸附在 CNT 上仍然是一个问题，并且该方法仅对纯化样品有用。关于检测机制，除了电荷转移、肖特基势垒（SB）修饰和其他作者报道的散射势之外，还确定了导致滞后修饰的电子/空穴俘获机制。聚合物的存在似乎阻碍了电极-CNT 接触的调制。
