In this study, we developed the first heterotrimeric fluorescent aptasensor for detecting saxitoxin (STX), utilizing a synergistic target-induced conformational change method. The aptasensor pairs TO as a signaling probe with aptamer 73a, discovered via Capture-SELEX, as the recognition element. In the absence of STX, TO shows weak fluorescence, but in its presence, a hybrid G-quadruplex forms, significantly enhancing fluorescence. We explored the binding modes and interactions of 73a, ligand STX, and TO fluorescent probe in heterotrimers. Molecular dynamics simulations revealed three trimerization modes, with STX and TO stabilizing each other in the G-quadruplex plane. We expanded the framework of aptamer design by proposing a novel strategy based on multi-molecular assemblies, which leverages intricately interlocked molecular interactions to enhance the specificity and affinity of aptamers. The aptasensor detects STX in the range of 10 pM to 50 nM, with a limit of 0.22 pM, and demonstrates high accuracy in seawater and shellfish samples, offering a simple, rapid, and costeffective method for environmental monitoring.

Although high-affinity and high-specificity aptamers can be obtained by SELEX (Systematic Evolution of Ligands by Exponential Enrichment), and have good activity in vitro, their performance in vivo is poor. This is mainly because of the degradation of linear nucleic acids by nucleases in body fluids and the difficulty of maintaining stable 3D structures in complex body fluid environments, which seriously hinders the clinical application of aptamers. This makes circular aptamers, which can resist degradation and are more stable in complex body fluid environments, an attractive option. However, the cyclization process may have a considerable impact on the structure of the original linear aptamer, and blind cyclization may lead to a decrease in its affinity. Here, we developed a new method to guide the cyclization of saxitoxin (STX) aptamers based on molecular computation, and verified the activity of circular aptamers through bioactivity experiments to further verify the authenticity and reliability of our methods. Consistent with the computational analysis, although circularization disrupts the G4 structure, circular aptamer not only has a higher affinity than the linear one but also provides certain protection to mice and greatly prolongs their survival, which proves the accuracy and reliability of the circular structure designed by our computational method. Our findings provide important ideas for better guidance in the design of circular aptamers and demonstrate their great potential in therapeutic applications. ### Competing Interest Statement The authors have declared no competing interest. National Natural Science Foundation of China [grant number 82173732]; National Key R&D Program of China [grant numbers 2019YFC0312600 and 2019YFC0312603]

Saxitoxin (STX) is one of the potent marine biotoxins that has high rate of lethality. However, there are no effective treatments at present, and the existing detection methods need to be further explored because of ethical problems or technical limitations. In this work, oligonucleotide aptamers toward STX were screened based on immobilizing libraries on Immobilized Metal-Chelate (IMC), such as Ni-NTA Sepharose, and the IMC-SELEX was conducted by the G-quadruplex library and the random library, respectively. Aptamer 45e (from the G-quadruplex library) and aptamer 75a were obtained after optimization, and aptamer 45e turned out to have a higher affinity toward STX. Furthermore, it was found that the hydrogen bonding and the van der Waals forces (VDW) played major roles in the high efficiency and specificity between STX and 45e by means of molecular docking and dynamics simulation. Based on this, aptamer 45e-1 with the K-d value of 19 nM was obtained by further optimization, which was then used to construct a simple, label-free and real-time optical BLI aptasensor for the detection of STX. This aptasensor showed good reproducibility and stability. In summary, with the advantages of screening aptamers of high efficiency and specificity toward the targets, the proposed IMC-SELEX provides a promising screening strategy for discovering aptamers, which could be used as the potential molecular recognition elements in the fields of biomedicine, food safety and environmental monitoring.

Photodynamic therapy (PDT) is a new therapeutic strategy for hypertrophic scars (HS), but it is limited by low drug utilization. Transdermal delivery based on nanoethosomes (ES) has attracted considerable attention as a potential clinical strategy in PDT treating HS. However, free ES are unsatisfactory due to their instability and non-targeting, which causes non-effective delivery and low drug utilization. Herein, 5-aminolevulinic acid (ALA)-loaded ES (ES-ALA) embedded in hyaluronic acid (HA) meshes (HA/ES-ALA), a novel synergistic transdermal delivery nanogel, are developed for enhancing PDT of HS. HA/ES-ALA has a unique structure and property to protect unilaminar ES-ALA with HA meshes and actively target hypertrophic scar fibroblasts (HSFs) with HA receptors. Bothin vitroandin vivoexperiments demonstrate that HA/ES-ALA has a remarkable transdermal delivery ability with penetrating channels and a membrane-fusion mechanism. Meanwhile, the synergistic delivery mechanism is visually characterized as three stages: synergistic penetration, targeting aggregation and transmembrane delivery. With the synergistic effect, HA/ES-ALA can realize a targeted transdermal delivery, and significantly improve ALA utilization and enhance PDT efficacy. The results demonstrate an effective transdermal delivery route to enhance therapy for HS as well as other skin diseases.

This study aimed to explore the role of the miR-146a-5p/TRAF6/NF-KB axis in chondrocyte apoptosis. Transcriptome sequencing for microRNA expression in control and osteoarthritic cartilage was performed. Bioinformatic analysis was performed to identify the target genes of miR-146a-5p, and subsequently, Gene Ontology (GO) terms and KEGG pathways were identified. Furthermore, protein–protein interactions were analyzed to identify the hub regulatory gene of miR-146a-5p. MiR-146a-5p mimic, inhibitor and the corresponding negative control were constructed, and the apoptosis rates were measured in the transfected groups by flow cytometry, TUNEL staining and Western blot. Potential miRNA-target interactions were identified by dual-luciferase reporter assay. The microRNA array demonstrated that miR-146a-5p was significantly upregulated in osteoarthritic tissues, which was further confirmed by PCR analysis. Compared with the control group, IL-1β significantly decreased the viability of chondrocytes, while coculture with miR-146a-5p inhibitor rescued the IL-1β-induced inhibition of chondrocyte viability. Western blot results also identified the proapoptotic effects of miR-146a-5p. Bioinformatic analysis results revealed that miR-146a-5p targeted 159 potential genes, and TRAF6 was the hub gene among the 159 genes. The relative expression of TRAF6 was significantly decreased in the IL-1β-induced group. When siTRAF6 was added, apoptosis was significantly increased. Luciferase reporter assays showed that luciferase activity of the TRAF6 3′-UTR reporter was decreased in chondrocytes after transfection with the miR-146a-5p mimic. This work showed that miR-146 induces chondrocyte apoptosis by targeting the TRAF6-mediated NF-KB signaling pathway, and miR-146 may be a potential target for OA treatment.

Diarrhetic shellfish toxins (DSTs) are marine toxins distributed widely in the world, which pose a major threat to the health of mankind. Dinophysistoxin-1 (DTX-1) has the most potent toxicity in DSTs. However, the current detection methods have ethical problems and technical defects. Further research is needed, to develop a more suitable alternative to the supervision system. In this work, we successfully obtained an aptamer with high affinity and specificity bound to DTX-1 for the first time. After optimization, a core sequence of the aptamer with a higher KD of 64 nM was obtained, while the binding mode of the core sequence and DTX-1 was explored. Based on this aptamer, we developed a biolayer interferometry (BLI) biosensor platform for DTX-1 detection. The aptasensor exhibited a broad detection range from 40 to 600 nM DTX-1 (linear range from 80 to 200 nM), and the low detection limit was 614 pM. Morever, the aptasensor showed good reproducibility and stability, which indicated that this novel aptasensor had broad development prospects for the sensitive and rapid detection of DTX-1.

This paper provides a feasible model for molecular structure analysis and interaction mechanism of aptamer and micromolecule. In this study, modeling and dynamic simulation of ssDNA aptamer (P-18S2) and target (Palytoxin, PTX) were performed separately. Then, the complex structure between DNA and PTX was predicted, and docking results showed that PTX could combine steadily at the groove's top of DNA model by strong hydrogen-bonds and electrostatic interaction. Thus, we truncated and optimized P-18S2 by simulating. At the same time, we also confirmed the reliability of simulation results by experiments. With the experimental and computational results, the study provided a more reasonable interpretation for the high affinity and specific binding of P-18S2 and PTX, which laid the foundation for further optimization and development of aptamers in molecular diagnostics and therapeutic applications.

To translate and cross-culturally adapt Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) Questionnaire into a Simplified Chinese version (QuickDASH-C), and evaluate the reliability and validity of the QuickDASH-C in patients with upper limb disorders. Cross-cultural adaptation was performed according to the internationally recognized guidelines of American Academy of Orthopedic Surgeons Outcome Committee. A total of 150 participants were recruited in this study. Internal consistency was estimated using Cronbach’s alpha. Intra-class correlation coefficient (ICC) was used to determine test-retest reliability. Construct validity was analyzed by evaluating the correlations between QuickDASH-C and Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire and visual analogue scale (VAS) as well as the short form (36) health survey (SF-36). The original version of the QuickDASH was well cross-culturally adapted and translated into Simplified Chinese. QuickDASH-C was indicated to have excellent reliability (Cronbach’s alpha = 0.818, ICC = 0.907). QuickDASH-C correlated almost perfectly to DASH (r = 0.820, p < 0.001). Moderate to substantial correlations between QuickDASH-C and VAS (r = 0.463, p < 0.001), as well as physical function (r = − 0.630, p < 0.001), role physical (r = − 0.471, p < 0.001), bodily pain (r = − 0.563, p < 0.001) and general health (r = − 0.414, p < 0.001) subscales of SF-36, were observed. QuickDASH-C was demonstrated to have excellent acceptability, reliability, and validity in patients with upper limb disorders, which could be recommended for patients in mainland China. • This study translated and cross-culturally adapted Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) questionnaire into a Simplified Chinese version. • The reliability and validity of Simplified Chinese version of QuickDASH were good in evaluating patients with upper limb disorders.

The incidence of deep fungal infection due to non-albicans Candida species (especially Candida glabrata) has significantly increased in recent decades. Candida glabrata is an opportunistic pathogen of low virulence which mainly invades the gastrointestinal, genitourinary, and respiratory tracts, but has rarely been reported as complication of articular surgery in the literature. We present a case of knee fungal arthritis caused by C. glabrata after a minimally invasive arthroscopic surgery. In this case, the patient's knee got infected after arthroscopic treatment for a recurrent popliteal cyst, and she was unable to be cured by either debridement or antifungal drugs. Mycological and molecular identification of the necrotic tissues isolate revealed C. glabrata as etiologic agent. We originally planned to conduct a debridement once again, but it was found that the articular cartilage was extensively damaged during the operation. Besides, the magnetic resonance imaging of the affected knee also showed that the infection had invaded the subchondral bone. So we treated this case with a two-stage primary total knee arthroplasty with an antibiotic-laden cement spacer block. After a 10-month follow-up, the patient had completely recovered and has not experienced any recurrence to date. In addition, we review 21 cases of C. glabrata-induced infectious arthritis described to date in the literature.

Traditionally, the development of osteoarthritis (OA) is associated with factors such as aging and injure, but more and more epidemiological and biological evidence suggests that the disease is closely related to metabolic syndrome and metabolic components. Ubiquitin-specific protease 3(USP3), a member of the USPs family, is a specific protease capable of cleavage of ubiquitin chains linked by proline residues. In our presented study, we firstly found that USP3 expression level was decreased in OA. USP3 overexpression inhibited IL-1β induced chondrocytes apoptosis and nuclear factor κB (NF-κB) activation. USP3 knockdown induced chondrocytes apoptosis and activated NF-κB pathway. USP3 interacts with TRAF6 (tumor necrosis factor-receptor-associated factor 6), which is an essential adaptor protein for the NF-κB (nuclear factor κB) signaling pathway and plays important roles in inflammation and immune response. IL-1β treatment up-regulated the polyubiquitination of TRAF6 in chondrocytes, which was attenuated when USP3 was forced expression. Our study mechanistically links USP3 to TRAF6 in osteoarthritis development. Moreover, these data support the pursuit of USP3 and TRAF6 as potential targets for osteoarthritis therapies.

Contamination of freshwater with nodularin-R (NOD-R) represents a significant global environmental and public health concern. However, ethical problems and technical difficulties surrounding the current detection methods for NOD-R necessitate further studies to devise appropriate alternatives within a regulatory monitoring regime. In this work, we employed an aptamer as a specific recognition element and developed a biolayer interferometry (BLI) biosensor platform for NOD-R detection. The aptasensor we propose displayed a broad detection range from 40 to 600 nM NOD-R (and a linear response range from 40 to 200 nM), and achieved a detection limit as low as 167 pM. In addition, the aptamer-based biosensor was shown to possess high selectivity, as well as good reproducibility and stability. We believe that this novel aptamer-based biosensor provides a potential alternative for the sensitive and rapid detection of NOD-R.

Nodularin-R (NOD-R),a cyanophycean toxin,is a potent hepatotoxin.However,there are different limitations of the detection methods for NOD-R.As a result,there is still an urgent need to develop a novel approach for the detection of NOD-R.Here,we combined High Throughput Sequencing (HTS) with Systematic Evolution of Ligands by Exponential Enrichment (SELEX) method (HT-SELEX),and selected aptamer that bound with high affinity and specificity to NOD-R.Biolayer interferometry (BLI) assays showed that aptamer H62 was the best one targeting NOD-R.The binding affinity between aptamer H62 and NOD-R was as high as 168 nM.Furthermore,aptamer H62 bound with high specificity to NOD-R.These results indicate that aptamer H62 would be a new molecular recognition element and provide clues for the construction of aptasensor specializing in NOD-R detection.