Jiangsu Normal University

Serotonin is a crucial neurotransmitter, with its levels being particularly significant for life safety. Here, a self-quenching electrochemiluminescence (ECL) biosensor was designed for serotonin assay based on DNA tetrahedral nanostructures (DTNs)-enhanced catalytic hairpin assembly (CHA). In this work, stimuli-responsive serotonin aptamer-cross-linked DNA-stabilized microcapsules loaded with DTNs were presented. The presence of serotonin effectively controlled the release of abundant DTNs, achieving enzyme-free signal amplification and transduction. Specifically, DTNs featuring a rigid 3D framework and multi-sites exhibited high collision efficiency, thereby achieving a high reaction efficiency of CHA. On the basis of ECL resonance energy transfer (ECL-RET), the ECL emission of CdS QDs was quenched by proximal Au nanoparticles (Au NPs). The proposed sensor showed excellent performance in self-quenching detection of serotonin ranging from 1.0 pM to 1.0 μM with a low detection limit of 0.3 pM. Moreover, satisfactory results were obtained while detecting serotonin in human serum and cell lysate samples. Overall, the proposed method presented a promising and straightforward platform for the trace detection of serotonin.

Amyloid β oligomer (AβO) is not only a crucial biomarker but also a potential therapeutic target for Alzheimer's disease (AD). Here, a type of ternary photoactive hybrids (CdS/ZnS/Bi₂Se₃) was used as a substrate material to construct a photoelectrochemical (PEC) biosensor for dual-quenching detection of AβO. Due to the cooperative band gap excitations and multi-interfacial charge transfer of the three components, CdS/ZnS/Bi₂Se₃ ternary hybrids possessed self-enhanced photocurrent, which significantly boosted PEC responses. The broad-spectrum absorption and peroxidase-mimicking catalytic property of PtCu nanoflowers (NFs) achieved the synergistic dual-quenching effect, which displayed a more sensitive response than common single-quenching PEC biosensors. Impressively, an efficient dynamic signal amplification strategy was established by DNA cascade reaction-activated DNA walker, improving the walk speed and high reaction efficiency. As a result, the constructed biosensor realized the detection of AβO ranging from 20 fM to 10 nM with a detection limit of 4.4 fM. In comparison to previously reported methods, the biosensor enabled the reliable detection of AβO in blood specimens from AD patients and healthy volunteers, demonstrating high sensitivity, specificity, stability, and reproducibility. By simply replacing the aptamer sequences, this strategy could be applied for other biomarker detection with a high potential to inspire innovative sensing approaches, offering some useful help for biomedical research and disease diagnosis.

Porcine reproductive and respiratory syndrome virus (PRRSV) is a major and highly contagious swine pathogen that severely impacts the global pork industry. Typically, porcine alveolar macrophages (PAM) isolated from pigs and infected with PRRSV are used to analyze viral pathogenesis, although it remains unclear whether it accurately reflects the in vivo disease process. In this study, scRNA-seq analysis revealed distinct transcriptional profiles between in vitro-cultured and freshly isolated PAMs. Inflammation, apoptosis, autophagy, and the TNF signal pathway were activated both in vivo and in vitro, however, only partial enriched GO terms and KEGG pathways were coincidental. Notably, PRRSV genomes were detected in the T and B cells in vivo, indicating a potential effect of PRRSV on T and B cell function. Results also showed that although PRRSV infection triggered robust inflammation, only a minority of PAMs were infected. Interestingly, bystander cells displayed similar inflammatory responses to those of PRRSV-infected cells, hinting at the role bystander cells play in the inflammatory response. Through scRNA-seq analysis, transcriptomic profiling of cells pre- and post-PRRSV infection revealed several distinct subclusters (S0-S7 and SS0-SS6), with the S5 subpopulation exhibiting the highest PRRSV infection rate and the SS6 subpopulation showing the fastest PRRSV replication rate. The SLAMF7 gene emerged as a key gene in these two subpopulations infected with PRRSV. Knockdown of SLAMF7 significantly reduced PRRSV infection and suppressed PRRSV-induced inflammation, while its overexpression promoted replication of PRRSV and inflammation induced by PRRSV.