Isopropyl β-D-thiogalactopyranoside (IPTG), while widely utilized for inducing gene expression in systems governed by T7 lac and related promoters, poses significant challenges due to its toxicity and expense, prompting the exploration of alternative induction strategies. In this study, we developed a series of inducer-free vitamin B 12 -producing strains featuring thermally regulated pathway genes. We engineered a thermal switch by replacing the lacI promoter with the P R promoter, which is regulated by the temperature-sensitive repressor cI857 from the λ bacteriophage. As a result, target genes driven by T7 lac or other lac -derived promoters containing lac operators were expressed upon lowering the temperature. Our findings indicate that culturing at 37°C and then shifting to 32°C when the optical density at 600 nm reaches 2 is the most effective strategy for vitamin B 12 production. Additionally, the vitamin B12 titer increased by 37.96% after introducing an ssrA degradation tag at the C-terminus of lacI . This study introduces a novel strategy for vitamin B 12 production that circumvents the need for IPTG by implementing a thermal switch. This approach may have significant implications for chemical bioproduction processes that have traditionally relied on IPTG for gene induction.
Zhuoer Cai,Xinyi Zhang,Shiyue Xiao,Shuwang Ge,Xianmin Liu,Yinan Zhang,Long Chen,Xiu-Ni Hua,Baiwang Sun
Phase change materials (PCMs) have drawn increasing attention for their promising applications in thermal switches, data communication, and energy storage. Because of the complexity of the interactions between molecules, it is still a challenge to design PCMs with a desired high phase transition temperature (Tc). In this study, a one-dimensional hybrid perovskite of (TEACCl)PbBr3 (1, TEACCl = Et3NCH2Cl) was successfully designed and synthesized with a Tc = 390 K. Disordering of TEACCl+ on the heating process is the origin of the structural phase transition of 1 from the P21/c to P63/mmc structure. It is noted that the phase transition is associated with an excellent switchable dielectric property, which indicates that 1 has the potential to be applied to sensor equipment. After calculation, 1 is an infrequent indirect bandgap semiconductor with an energy gap of 3.57 eV. Moreover, 1 exhibits strong red fluorescence under irradiation of UV light. This work will provide guidance for designing high Tc switching materials.
Shuangling Wang,Jie Lv,Yu Pang,Shuyang Hu,Yulong Lin,Meng Li
Despite significant achievement in chemotherapy, the off-target actions and low pharmaceutical selectivity of the therapeutic agents still limit their clinical efficacy. Herein, a multifunctional nanoplatform which integrates chemotherapy, chemodynamic therapy (CDT) and photoactivation of TRPV1 channels has been successfully established for specific cancer therapy. Polydopamine (PDA) coated hollow prussian blue nanocages (hPBNCs) are used as the photothermal switches and drug carriers for loading chemotherapeutic drug, doxorubicin (Dox). Conjugating with the TRPV1 antibodies enables the nanoplatform to bind specifically to TRPV1 channels on the plasma membrane of the TRPV1-positive cancer cells and then activate them by local heating upon NIR irradiation, leading to the over-influx of Ca2+. Critically, the laser irradiation can be carefully controlled to not only open the TRPV1 channels but also avoid burning of tumors by hyperthermia. Moreover, the exposed hPBNCs in the acidic tumor cells can decompose endogenous H2O2 into ˙OH by Fenton reaction to realize CDT, which further aggravates cancer cell apoptosis. Together with the chemotherapy caused by Dox, our nanoplatform displays an enhanced anticancer effect both in vitro and in vivo. Our work provides a powerful means for site-specific cancer synergetic therapy with high spatial and temporal resolution.
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