Using heme entrapped in recombinant silk films, we have produced 3rd generation biosensors, which allow direct electron transfer from the heme center to an electrode avoiding the need for electron mediators. Here, we demonstrate the use of these heme-silk films for the detection of nitric oxide (NO) at nanomolar levels in the presence and absence of oxygen. The sensor was prepared by drop-casting a silk solution on a glassy carbon electrode modified with multiwalled carbon nanotubes (MWCNT) followed by infusion with heme. The sensor was characterized by cyclic voltammetry and showed well defined and reversible Fe⁺/ Fe³⁺ redox couple activity, with NO detection by oxidation at potentials above +0.45 V or reduction at potentials below − 0.7 V. Evaluation of the effect of pH on the sensor response to NO reduction indicated a maximum response at pH 3. The sensor showed good linearity in the concentration range from 19 to 190 nM (R² = 0.99) with a detection limit of 2 nM. The sensor had excellent selectivity towards NO with no or negligible interference from oxygen, nitrite, nitrate, dopamine and ascorbic acid and retained 86% of response after 2 months of operation and storage at room temperature.

使用包裹在重组丝膜中的血红素，我们生产了第三代生物传感器，该传感器可将电子从血红素中心直接转移到电极，而无需使用电子介体。在这里，我们演示了使用这些血红素丝膜在存在和不存在氧气的情况下以纳摩尔水平检测一氧化氮（NO）的用途。通过将丝溶液滴铸在用多壁碳纳米管（MWCNT）修饰的玻璃碳电极上，然后注入血红素来制备传感器。该传感器通过循环伏安法进行了表征，并显示出定义明确且可逆的Fe ⁺ / Fe ³⁺氧化还原对活性，在+0.45 V以上的电位通过氧化检测NO，或在− 0.7 V以下的电位通过还原检测NO。评估pH对传感器对NO还原响应的影响表明在pH 3时响应最大。该传感器表现出良好的线性浓度范围为19到190 nM（R ² = 0.99），检测极限为2 nM。该传感器对NO的选择性极佳，不受氧气，亚硝酸盐，硝酸盐，多巴胺和抗坏血酸的干扰，或在微不足道的干扰下运行，并在室温下储存和运行2个月后仍保留了86％的响应。