Upregulated Transcription and Carbon Fixation in <i>Brassica Rapa</i> Var. <i>Chinensis</i> via Light Conversion Films Based on Coordination Polymer Nanosheets

In the context of global carbon neutrality, light conversion agents characterized by spectral matching capability and high stability have emerged as promising candidates to enhance CO2 fixation and agricultural productivity. We fabricated light conversion films (LCFs) incorporating europium-based coordination polymer nanosheets (Eu-CPNs). The nanosized structures of Eu-CPNs, fabricated by ultrasonic exfoliation of bulk coordination polymer Eu-CP, are uniformly dispersed within the thermoplastic polyurethane (TPU) matrix, exhibiting seamless interfacial interactions. Notably, this is the first time Eu-CP, or even CPs, has been used for practical application in plant growth regulation as light conversion agents. Compared with plants under the control check (CK) film, Brassica rapa var. Chinensis growing under LCFs had a 77.9% increment in daily CO2 assimilation at the whole plant level, and its fresh aboveground weight and total dry weight increased by 92.0% and 79.7%, on average, respectively. Further, the gene transcriptional response of plants revealed that LCFs significantly upregulated the transcription of genes related to photosynthesis and carbon metabolism. LCFs based on coordination polymer nanosheets evidently improved the utilization efficiency of solar energy and the growth of plants by light conversion, holding great potential for carbon neutrality and the green development of protected horticulture.