Here we present a simple and low-cost production method to generate paper-based microfluidic devices with wax for portable bioassay. The wax patterning method we introduced here included three different ways: (i) painting with a wax pen, (ii) printing with an inkjet printer followed by painting with a wax pen, (iii) printing by a wax printer directly. The whole process was easy to operate and could be finished within 5-10 min without the use of a clean room, UV lamp, organic solvent, etc. Horse radish peroxidase, BSA and glucose assays were conducted to verify the performance of wax-patterned paper.

Plants often face the challenge of severe environmental conditions, which include various biotic and abiotic stresses that exert adverse effects on plant growth and development. During evolution, plants have evolved complex regulatory mechanisms to adapt to various environmental stressors. One of the consequences of stress is an increase in the cellular concentration of reactive oxygen species (ROS), which are subsequently converted to hydrogen peroxide (H(2)O(2)). Even under normal conditions, higher plants produce ROS during metabolic processes. Excess concentrations of ROS result in oxidative damage to or the apoptotic death of cells. Development of an antioxidant defense system in plants protects them against oxidative stress damage. These ROS and, more particularly, H(2)O(2,) play versatile roles in normal plant physiological processes and in resistance to stresses. Recently, H(2)O(2) has been regarded as a signaling molecule and regulator of the expression of some genes in cells. This review describes various aspects of H(2)O(2) function, generation and scavenging, gene regulation and cross-links with other physiological molecules during plant growth, development and resistance responses.

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Paper-based microfluidics is a promising technology to develop a simple, low-cost, portable, and disposable diagnostic platform for resource-limited settings. Here we report the fabrication of paper-based microfluidic devices in nitrocellulose membrane by wax printing for protein immobilization related applications. The fabrication process, which can be finished within 10 min, includes mainly printing and baking steps. Wax patterning will form hydrophobic regions in the membrane, which can be used to direct the flow path or separate reaction zones. The fabrication parameters like printing mode and baking time were optimized, and performances of the wax-patterned nitrocellulose membrane such as printing resolution, protein immobilization, and sample purification capabilities were also characterized in this report. We believe the wax-patterned nitrocellulose membrane will enhance the capabilities of paper microfluidic devices and bring new applications in this field.