Yongli Zhang,Zhenyun He,Zhichang Sun,Sihang Zhang,Xing Liu
Ochratoxin A (OTA) poses significant risks to both environment and human health, necessitating the development of rapid and sensitive detection methods. Lateral flow immunosensors (LFIs) typically use monoclonal antibodies and artificial antigens for mycotoxin detection; however, the preparation of these components is time-intensive, laborious, costly, and environmentally harmful. Herein, we developed an innovative genetic engineering-powered colorimetric/fluorescent dual-mode LFI (CM/FL-dLFI) using nanobodies and the mimotope peptide (MP) of OTA. Initially, a heptameric bifunctional fusion (sfGFP-C4bpα-Y4) containing the superfolder green fluorescent protein, the C4-binding protein α-chain, and the MP Y4 was constructed. The fusion was subsequently labeled on gold nanoflowers (AuNFs) to create the AuNFs@sfGFP-C4bpα-Y4 probe, which can be captured by the nanobody heptamer (Nb-C4bpα) and provides colorimetric/fluorescent signals. The optimized CM/FL-dLFI achieved a colorimetric limit of detection (LOD) of 0.01 ng/mL and a fluorescent LOD of 0.05 ng/mL. It exhibited high selectivity for OTA, good recovery rates of 82.85–102.81 % with relative standard deviations not exceeding 14 %, and excellent long-term stability. Moreover, it showed strong correlation with high-performance liquid chromatography in the analysis of 11 real pepper samples. Therefore, this study highlights the promising application potential of nanobodies and MPs in developing an economical and eco-friendly LFI for OTA detection in pepper.
Maintaining quiescence of stem cells is a potential way to decrease cell nutrition demand for restoring the organization. Herein, a biomimetic peptide to maintain quiescence of stem cells through C-X-C motif chemokine ligand 8 (CXCL8)-C-X-C motif chemokine receptor 1 (CXCR1) pathway against intervertebral disc degeneration (IVDD) is developed. First, it is confirmed that quiescence can be induced via inhibiting phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway in nucleus pulposus stem cells (NPSCs). Meanwhile, it is well known that CXCR1, a chemokine receptor, can be targeted by CXCL8, resulting in cell proliferation via activating PI3K/Akt/mTOR pathway. Second, a biomimetic peptide (OAFF) that can bind to CXCR1 and form fibrous networks on NPSCs, mimicking extracellular matrix formation is developed. The multivalent effect and long-term binding to CXCR1 on NPSCs of OAFF fibers offer forcefully competitive inhibition with natural CXCL8, which induces NPSCs quiescence and ultimately overcomes obstacle in intradiscal injection therapy. In rat caudal disc puncture model, OAFF nanofibers still maintain at 5 weeks after operation and inhibit degeneration process of intervertebral disc in terms of histopathology and imageology. In situ fibrillogenesis of biomimetic peptide on NPSCs provides promising stem cells for intradiscal injection therapy against IVDD.
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