Surface-enhanced
Raman scattering (SERS) technique has been limitedly
applied to the detection of trace thiram due to the weak activity
of employed substrates. In this work, Au–Ag nanoparticles (NPs)
with controllable morphologies are synthesized and used as SERS-active
substrates for the detection of trace thiram. Porous–spiny
Au–Ag NPs are synthesized with spherical Ag NPs as intermediates
through in situ redox. Annular Au–Ag NPs can be further obtained
by heating porous–spiny Au–Ag NPs. Here, the morphology
transformation of Au–Ag NPs is first completed by means of
the element diffusion theory, providing a strategy for the morphology
control of complex Au–Ag NPs. Additionally, these Au–Ag
NPs with optimized morphologies were chosen as substrates for the
successful SERS detection of trace thiram. Especially, porous–spiny
Au–Ag NPs show superior sensitivity and reproducibility. Meanwhile,
using porous–spiny Au–Ag NPs as SERS-active substrates,
thiram can be quantitatively detected in the range from 10–3 to 10–11 M. Thus, it is inferred that Au–Ag
NPs with optimized morphologies will have great potential in the field
of trace analyte detection related to food safety and environmental
protection.
Background: Chinese hamster ovary (CHO) cells are the most dependable mammalian cells for the production of recombinant proteins. Replication-incompetent retroviral vector (retrovector) is an efficient tool to generate stable cell lines. Multiple copies of integrated genes by retrovector transduction results in improved recombinant protein yield. HEK-293 and their genetic derivatives are principal cells for retrovector production. Retrovectors packaged in HEK-293 cells pose a risk of infectious agent transmission, such as viruses and mycoplasmas, from serum and packaging cells. Results: In this report, retrovectors were packaged in CHO cells cultured in chemically defined (CD) media. The retrovectors were then used to transduce CHO cells. This method can block potential transmission of infectious agents from serum and packaging cells. With this method, we generated glucagon-like protein-1 Fc fusion protein (GLP-1-Fc) stable expression CHO cell lines. Productivity of GLP-1-Fc can reach 3.15 g/L. The GLP-1-Fc protein produced by this method has comparable bioactivity to that of dulaglutide (Trulicity). These stable cell lines retain 95-100% of productivity after 40 days of continuous culture (~48-56 generations). Conclusions: Suspension CHO cells are clean, safe, and reliable cells for retrovector packaging. Retrovectors packaged from this system could be used to generate CHO stable cell lines for recombinant protein expression. How to cite: Li J, Wei S, Cao C, et al. Retrovectors packaged in CHO cells to generate GLP-1-Fc stable expression CHO cell lines. Electron J Biotechnol 2019;41. https://doi.
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