Background: Molecular imprinting is a technology used to produce artificial receptors that simulate the molecular recognition in the nature and prepare the polymer network structure in the presence of template molecule. Molecularly imprinted visual sensor combines the advantages of specific recognition via molecular imprinting and fast response speed via visualization. The aims of this paper are to prepare a portable visual sensor for Horseradish Peroxidase (HRP) recognition based on molecularly imprinted hydrogel.

Methods: At first, HRP-imprinted polyacrylamide hydrogels with 1 mm thickness were obtained by one-step synthesis via radical induced in-situ polymerization of acrylamide using acrylamide (AAm) as the functional monomer, N,N'-Methylenebisacrylamide (MBA) as the crosslink agent and HRP as the template molecule.

Results: Compared with nonimprinted hydrogels, the HRP-imprinted hydrogel sensor showed significant color changes in response to the target HRP. This visual sensor was constructed based on 3, 3', 5, 5'- tetramethyl benzidine (TMB) - H2O2 color reaction system by HRP catalyzing to produce color change through digital photography and image analysis (RGB system). The HRP-imprinted hydrogel showed good response in the range of 0.001-0.5 mg/mL and had a significant specific recognition compared to other proteins via selective test.

Conclusion: The proposed portable visual sensor could be used for qualitative and semi-quantitative analysis of HRP with high selectivity and reasonable regeneration. The sensor has the advantages of simple operation, low cost, no special equipment, and can be applied to serum sample with less sample consumption and no need of sample preparation. It has wide application prospects in microfluidic devices, biomimetic sensors, flexible biosensor and membrane separation technology.

背景：分子印迹是一种用于产生人工受体的技术，该受体模拟自然界中的分子识别并在模板分子存在下制备聚合物网络结构。分子印迹视觉传感器结合了通过分子印迹进行特异性识别和通过可视化实现快速响应的优势。本文的目的是基于分子印迹水凝胶制备用于辣根过氧化物酶（HRP）识别的便携式视觉传感器。

方法：首先，以丙烯酰胺（AAm）为功能单体，以N，N'-亚甲基双丙烯酰胺（MBA）为自由基，通过自由基诱导的丙烯酰胺原位聚合一步合成，得到厚度为1 mm的HRP印迹聚丙烯酰胺水凝胶。交联剂和HRP作为模板分子。

结果：与非印迹水凝胶相比，HRP印迹水凝胶传感器响应目标HRP表现出明显的颜色变化。该视觉传感器是基于3、3'，5、5'-四甲基联苯胺（TMB）-H2O2显色反应系统，通过HRP催化通过数字摄影和图像分析（RGB系统）产生颜色变化的。经选择性测试，与其他蛋白质相比，HRP印迹水凝胶在0.001-0.5 mg / mL的范围内显示出良好的响应，并具有明显的特异性识别。

结论：该便携式视觉传感器可用于HRP的定性和半定量分析，具有高选择性和合理的再生性。该传感器具有操作简单，成本低廉，无需专用设备的优点，可用于血清样品，样品消耗少，无需样品制备。在微流体装置，仿生传感器，柔性生物传感器和膜分离技术中具有广阔的应用前景。