De novosynthesis of pH-responsive, self-assembled, and targeted polypeptide nano-micelles for enhanced delivery of doxorubicin.

Doxorubicin (DOX) is a commonly used anticancer drug, but it is inefficient as a therapeutic due to a lack of targeting. Peptide-tuned self-assembly of DOX offers a strategy to improve targeting for greater efficacy. In this work, we designed and prepared an amphiphilic tumor cell-targeting peptide, P14 (AAAAFFFHHHGRGD), able to encapsulate DOX by self-assembly to form tumor cell-targeting and pH-sensitive nano-micelles. The results showed a critical P14-micelle concentration of 1.758 mg l-1and an average particle size of micelles of 121.64 nm, with entrapment and drug-loading efficiencies of 28.02% ± 1.35% and 12.06% ± 0.59%, respectively. The prepared micelles can release 73.52 ± 1.27% DOX within 24 h in pH 4.5 medium, and the drug cumulative release profile of micelles can be described by the first-order model. Compared with free DOX, the micelles exhibited an increased ability to inhibit tumor cell growth and cause tumor apoptosisin vitro, with IC50values of DOX and P14-DOX micelles against human breast cancer cells (MCF-7) of 0.91 ± 0.07 and 0.75 ± 0.06µg ml-1, respectively, and cellular apoptotic rates of DOX and P14-DOX micelles of 70.3% and 42.4%, respectively. Cellular uptake experiments revealed high concentrations of micelles around and inside MCF-7 cells, demonstrating that micelles can target tumor cells. These results indicate the excellent potential for the application of this amphiphilic peptide as a carrier for small-molecule drugs and suggest a strategy for the design of effective anti-tumor drugs.

Bioconversion of farnesol and 1,4-dihydroxy-2-naphthoate to menaquinone by an immobilized whole-cell biocatalyst using engineered Elizabethkingia meningoseptica.

Menaquinone (MK) has important applications in the pharmaceutical and food industries. To increase the production rate (QP) of MK-4, we developed a straightforward biotransformation method for MK-4 synthesis directly from its precursors 1,4-dihydroxy-2-naphthoate (DHNA) and farnesol using whole cells of genetically engineered Elizabethkingia meningoseptica. Results showed that MK-4 can be produced directly from farnesol and DHNA using both free and immobilized FM-D198 cells. MK-4 yield peaked at 29.85 ± 0.36 mg/L in the organic phase and 24.08 ± 0.33 mg/g DCW after 12 h of bioconversion using free cells in a two-phase conversion system. MK-4 yield reached 26.34 ± 1.35 mg/L and 17.44 ± 1.05 mg/g DCW after 8 h using immobilized cells. Although this yield was lower than that using free cells, immobilized cells can be re-used for MK-4 production via repeated-batch culture. After ten batch cultures, efficient MK-4 production was maintained at a yield of more than 20 mg/L. After optimizing the catalysis system, the MK-4 yield reached 26.91 ± 1.27 mg/L using the immobilized cells and had molar conversion rates of 58.56 and 76.90% for DHNA and farnesol, respectively.