Peptides with an active redox molecule are incorporated into nanostructured films for electrochemical biosensors with stable and controllable physicochemical properties. In this study, we synthesized three ferrocene (Fc)-containing peptides with the sequence Fc-Glu-(Ala)_n-Cys-NH₂, which could form self-assembled monolayers on gold and be attached to antibodies. The peptide with two alanines (n = 2) yielded the immunosensor with the highest performance in detecting C-reactive protein (CRP), a biomarker of inflammation. Using electrochemical impedance-derived capacitive spectroscopy, the limit of detection was 240 pM with a dynamic range that included clinically relevant CRP concentrations. With a combination of electrochemical methods and polarization-modulated infrared reflection–absorption spectroscopy, we identified the chemical groups involved in the antibody-CRP interaction, and were able to relate the highest performance for the peptide with n = 2 to chain length and efficient packing in the organized films. These strategies to design peptides and methods to fabricate the immunosensors are generic, and can be applied to other types of biosensors, including in low cost platforms for point-of-care diagnostics.

具有活性氧化还原分子的肽被掺入具有稳定和可控物理化学性质的用于电化学生物传感器的纳米结构膜中。在这项研究中，我们合成了三个含有二茂铁（Fc）的肽，其序列为Fc-Glu-（Ala）_n -Cys-NH ₂可以在金上形成自组装的单分子层，并附着在抗体上。具有两个丙氨酸的肽（n = 2）使免疫传感器在检测炎症反应的生物标志物C反应蛋白（CRP）方面具有最高的性能。使用电化学阻抗衍生的电容光谱法，检测限为240 pM，动态范围包括临床相关的CRP浓度。结合电化学方法和偏振调制红外反射吸收光谱法，我们确定了抗体-CRP相互作用所涉及的化学基团，并且能够将n = 2的肽的最高性能与链长和有效包装相关联在有组织的电影中。这些设计肽的策略和制造免疫传感器的方法是通用的，