A DNAzyme-based electrochemical biosensor for magnesium ion (Mg²⁺) has been developed. Firstly, the Mg²⁺-dependent DNAzyme with thiol at the 5′-terminus is immobilized on a gold electrode through thiol–Au interaction. Then the substrate strand with ferrocene (Fc) at the 5′-terminus is attached to the gold electrode via hybridization with DNAzyme. In the absence of Mg²⁺, this sensor shows an obvious faradaic current from Fc. In the presence of Mg²⁺, the Fc-labeled substrate strand is cleaved into two pieces by catalytic action of DNAzyme and moves away from the electrode surface, which reduces the faradaic current. The current change provides quantitative measurement of Mg²⁺. The linear response range for the proposed biosensor is 0.2–5.0 mmol L⁻¹, and the detection limit is 0.05 mmol L⁻¹. Other divalent metals present do not interfere with Mg²⁺ detection. The sensor was applied to detect Mg²⁺ in serum with satisfactory results.

A weak codon usage bias was found in Dendrobium catenatum ( D. officiale ) antimicrobial peptides (AMPs), after the analysis of relative synonymous codon usage, GC contents, and the effective number of codons. The codon usage preference was mainly influenced by natural selection pressure. The self‐optimized prediction method and SWISS‐MODEL were applied for peptide structural and domain analyses, and some typical antimicrobial domains were found in D. officinale AMP amino sequences, such as knot1 domain, gibberellins‐stimulated domain, cupin_1 domain, defensin_like domain, and SLR1‐BP (S locus‐related glycoprotein 1 binding pollen coat protein) domain. To investigate the AMPs gene expression pattern, abiotic stresses, such as salt stress, drought stress, salicylic acid (SA), and methyl jasmonate (JA), were applied and the gene expression levels were detected by the real‐time fluorescent quantitative polymerase chain reaction. Results showed that, even though the basic AMPs gene expressions were low, some AMPs can still be induced by salt dress, while the drought dress did not show the same impact. The SA and JA signaling pathways might be involved in most of the AMPs expressions. The natural selection of the D. officinale AMPs and thus forming diverse types of AMPs enhanced the plant's innate immunity and disease resistance capability, which would lead to a better understanding of the molecular mechanism for D. officinale adapting to the environment. The finding that salt stress, SA, and JA signaling pathways can induce AMP expression lays a foundation for the further development and functional verification of D. officinale AMPs.

Through the applications of recycling sewage sludge to soils as nutrients, bisphenol A (BPA) and titanium dioxide nanoparticles (TiO2-NPs) are commonly found in the agricultural environment. Previous studies have reported that BPA and nanoparticles are harmful to the environment. However, the combined toxicity of both compounds is not yet understood. This work presented an in-depth proteomic analysis of Arabidopsis thaliana exposed to BPA and TiO2-NPs concurrently at environmentally relevant levels. Seeds were simultaneously treated with varying concentrations of BPA (0, 10, 100, and 1000 mu g.kg(-1)) and TiO2-NPs (0, 1, 10 and 100 mg.kg(-1)). In treatment of 1000 mu g.kg(-1) BPA and 100 mg.kg(-1) TiO2-NPs, highest seed germination rate (87.97%, p < 0.05) was observed. Shorter primary roots but more branched roots were obtained in treatments of high BPA and NPs concentrations (100, 1000 mu g.kg(-1) BPA and 10, 100 mg.kg(-1) TiO2-NPs) while no significant effects on plant height and biomass were found. In the comparative analysis, both concentration related positive and negative effects were observed, such as regulation of cell proliferation (positive), root hair elongation (positive), cellular response to oxidative stress (negative), and cell wall organization (negative). In response to the stress caused by BPA and TiO2-NPs, some proteins related to plant root development, such as CD48E, DNAJ2 and GL24, were up-regulated explaining the shorter primary root length and more branched roots. Moreover, Arabidopsis may have stimu-lated its ability of resource transportation and energy metabolism to overcome the stress and maintain or somehow enhance their growth by up-regulating proteins like TBB6, CALM1, RAA2A, G3PP2 and KASC1. Our comparative proteomics analysis also highlighted multiple biological processes that consequently lead to the stability of plant growth and its stress adaptation. The results demonstrated that applying biosolids to soil as a fertilizer may be considered as a sustainable practice.