The overuse of antibiotics in animal agriculture and medicine has caused a series of potential threats to public health. Macleaya cordata is a medicinal plant species from the Papaveraceae family, providing a safe resource for the manufacture of antimicrobial feed additive for livestock. The active constituents from M. cordata are known to include benzylisoquinoline alkaloids (BIAs) such as sanguinarine (SAN) and chelerythrine (CHE), but their metabolic pathways have yet to be studied in this non-model plant. The active biosynthesis of SAN and CHE in M. cordata was first examined and confirmed by feeding C-labeled tyrosine. To gain further insights, we de novo sequenced the whole genome of M. cordata, the first to be sequenced from the Papaveraceae family. The M. cordata genome covering 378 Mb encodes 22,328 predicted protein-coding genes with 43.5% being transposable elements. As a member of basal eudicot, M. cordata genome lacks the paleohexaploidy event that occurred in almost all eudicots. From the genomics data, a complete set of 16 metabolic genes for SAN and CHE biosynthesis was retrieved, and 14 of their biochemical activities were validated. These genomics and metabolic data show the conserved BIA metabolic pathways in M. cordata and provide the knowledge foundation for future productions of SAN and CHE by crop improvement or microbial pathway reconstruction.

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Antifouling surfaces that could reduce nonspecific adsorption from a complex matrix are a great challenge in surface plasmon resonance (SPR) sensors. An antifouling surface made by the covalent attachment of DNA tetrahedron probes (DTPs) onto gold surfaces demonstrated superior antifouling property against protein and cell. DTPmodified Au (DTPs−Au) film for two single protein samples (1 mg/mL myoglobin, 48 mg/mL HSA) and five complex matrices (100% serum, 100% plasma, 9.85 × 10 8 red cells/mL, 5% whole blood, and cell lysate) had low or ultralow adsorption amounts (≤8.0 ng/cm 2 ). More interestingly, DTPs−Au film could also avoid Au deposition on the surface in the process of the catalytic growth of gold nanoparticles (AuNPs). Thus, a low-fouling and sensitive SPR sensor for miRNA detection in a complex matrix was developed by integrating DTPs−Au film with the catalytic growth of AuNPs. Exploiting the amplification of catalytic growth of AuNPs, the detection limit was 0.8 fM toward target let-7a. Moreover, the SPR sensor revealed excellent selectivity and could distinguish let-7a from homologous family. More importantly, the SPR sensor could be feasible for determining miRNA in 100% human serum and cancer cell lysates, and the results of detecting miRNA from cancer cells were in excellent accord with the results obtained using qRT-PCR. This assay may have great potential as an miRNA quantification method in complex samples.

Alkaline phosphatase (ALP) is a significant biomarker in clinical diagnostics, and the abnormal level of ALP enzyme in serum is closely related to various diseases such as bone or liver cancer, bone metastases, and extrahepatic biliary obstruction. Herein a simple and portable photothermal biosensor was developed for sensitive detection of ALP enzyme based on the formation of polydopamine (PDA) nanoparticles using a thermometer or temperature discoloration sticker as readout. A MnO2 nanosheet was first prepared using a novel one-pot strategy which was operationally simple and not overly time-consuming. Then dopamine (DA) was quickly polymerized into PDA nanoparticles in the presence of the MnO2 nanosheet. When the model analyte ALP was present, the substrate 2-phospho-l-ascorbic acid trisodium salt (AAP) was catalytically hydrolyzed into l-ascorbic acid (AA), resulting in the inhibition of the formation of the PDA nanoparticles owing to the fact that the MnO2 nanosheet was reduced to Mn2+ by the generated AA. Thus, a portable biosensor based on the photothermal properties of PDA nanoparticles for ALP enzyme detection was established with a detection limit as low as 0.1 U/L (thermometer) and 1 U/L (temperature discoloration sticker). In addition, it also showed excellent sensing performance for the ALP assay in human serum. Such a simple, label-free, cost-effective, and sensitive assay could exhibit real potential application for ALP detection and early diagnosis, especially in developing countries or remote regions.

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