The development of green materials, especially the preparation of high-performance conductive hydrogels from biodegradable biomass materials, is of great importance and has received worldwide attention. As an aromatic polymer found in many natural biomass resources, lignin has the advantage of being renewable, biodegradable, non-toxic, widely available, and inexpensive. The unique physicochemical properties of lignin, such as the presence of hydroxyl, carboxyl, and sulfonate groups, make it promising for use in composite conductive hydrogels. In this review, the source, structure, and reaction characteristics of industrial lignin are provided. Description of the preparation method (physical and chemical strategies) of lignin-based conductive hydrogel is elaborated along with their several important properties, such as electrical conductivity, mechanical properties, and porous structure. Furthermore, we provide insights into the latest research advances in industrial lignin conductive hydrogels, including biosensors, strain sensors, flexible energy storage devices, and other emerging applications. Finally, the prospects and challenges for the development of lignin-conductive hydrogels are presented.

Spray-induced gene silencing (SIGS) represents an attractive avenue for plant protection, but limited uptake efficiency of double-stranded RNA (dsRNA) has restricted its application against the notorious oomycetes, Phytophthora. To control Phytophthora, dsRNAs targeting two essential genes in Phytophthora are screened for their ability to partially decrease Phytophthora capsici (P. capsici) infection and fecundity. To further facilitate SIGS for Phytophthora control, functionalized carbon dots (CDs) are complexed with the screened dsRNAs (dsRNA-CDs) through electrostatic interaction. dsRNA-CDs significantly enhanced the control efficacy of dsRNA against Phytophthora infestans, Phytophthora sojae, and both the wild-type and fungicide-resistant P. capsici. The synergism is based on enhancing dsRNA stability and internalization. Dual treatment with dsRNA-CDs and the corresponding fungicide reduced the amount of fungicide required to achieve the same protective effect by 90%. Plant RdRP1 is the main effector in processing various lengths of small RNAs to induce translation inhibition in Phytophthora. Notably, here the first application of a nano-delivery system to improve the effect of SIGS against Phytophthora pathogens is reported. Moreover, the elucidation of how CD facilitates dsRNA internalization in recipient cell and the molecular mechanism of SIGS can benefit the application of dsRNA-CDs in other plant-pathogen pathosystems through improving dsRNA bioactivity and reducing chemical fungicides application.

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