RESUMEN
Flexible electronics is expected to be one of the most active research areas in the next decade. In this study, a mechanically strong and flexible epoxy/GnP composite film was fabricated having a percolation threshold of electrical conductivity at 1.08 vol% GnPs and high thermal conductivity as 1.07 W m-1 K-1 at 10 vol% GnPs. The composite film shows high mechanical performance: Young's modulus and tensile strength were improved by 1344% and 66.7%, respectively, at 10 vol%. The film demonstrated high sensitivity to various mechanical loads: (i) it has gauge factors of 2 at strain range 0%-7% and 6 at range 7%-10%; (ii) it gives good electrical response with bending and twisting angles up to 180°; and (iii) it displays a good compressive load response up to 2 N where the absolute value of electrical resistance change increased by 71%. Furthermore, the film showed an excellent reliability up to 5.5 × 103 cycles with minor zero-point error. Above 20 °C, the film solely acts as a temperature sensor; upon cyclic temperature testing, the film demonstrated a stable resistive response in the range of 30-75 °C with a temperature sensitivity coefficient of 0.0063 °C-1. This flexible composite film has remarkable properties that enable it to be used as a full-fledged sensor for universal applications in aerospace, automotive and civil engineering.
RESUMEN
In this study, an antimicrobial peptide composed of three tandem repeats of Mytichitin-A (3 × Mytichitin-A) with a designed molecular weight of approximately 25 kDa was expressed in the green alga Chlamydomonas reinhardtii. The yield of 3 × Mytichitin-A reached 0.28% of the total soluble protein of the 3 × Mytichitin-A-expressing transgenic cells and the expression level was stable following continuous passaging of the cells for six months. Compared to its natural and yeast-produced recombinant counterparts, which showed a very low level of growth inhibition of gram-negative bacteria, the 3 × Mytichitin-A inhibited the growth of gram-negative bacteria at a minimum inhibition concentration value ranging between 60 and 80 µg/ml. The expressed 3 × Mytichitin-A did not show toxicity to HEK293 cells. Its bioactivity was hardly affected by temperature and pH but was impaired to some extent by the proteinase treatment. Taken together, our study showed that C. reinhardtii can be used as a cellular factory to produce bioactive Mytichitin-A in a multimeric format.
Asunto(s)
Antibacterianos/química , Antibacterianos/farmacología , Péptidos Catiónicos Antimicrobianos/genética , Péptidos Catiónicos Antimicrobianos/farmacología , Chlamydomonas reinhardtii/metabolismo , Antibacterianos/metabolismo , Péptidos Catiónicos Antimicrobianos/química , Péptidos Catiónicos Antimicrobianos/metabolismo , Chlamydomonas reinhardtii/genética , Endopeptidasas/metabolismo , Bacterias Gramnegativas/efectos de los fármacos , Células HEK293 , Humanos , Concentración de Iones de Hidrógeno , Pruebas de Sensibilidad Microbiana , TemperaturaRESUMEN
Chlamydomonas reinhardtii offers a great promise for large-scale production of multiple recombinant proteins of pharmaceutical and industrial interest. However, the nuclear-encoding transgenes usually are expressed at a low level, which severely hampers the use of this alga in molecular farming. In this study, the promoter of the endogenous intraflagellar transport 25 (IFT25) gene of C. reinhardtii was tested for its ability to drive the expression of green fluorescent protein (GFP), which functions as a readout for target gene expression. IFT25 promoter (IFT25P) alone was not able to drive GFP expression to a detectable level. IFT25P, however, can drive robust IFT25-GFP fusion protein expression when the intron-containing IFT25 gene was inserted between IFT25P and GFP cDNA. When an extended version of foot-and-mouth virus 2A protease (2AE) sequence was further inserted between the intron-containing IFT25 gene and the GFP cDNA, discrete GFP protein was observed to release from the IFT25-2AE-GFP polyprotein via 2A self-cleaving with a cleavage efficacy of approximately 99%. The monomer GFP was accumulated to a level of as high as 0.68% of total soluble proteins. To test whether the newly developed bicistronic IFT25P-IFT25-2AE expression system can be used to overexpress heterologous proteins of different origins and sizes, we inserted codon-optimized cDNAs encoding a Trichoderma reesei xylanase1 (25 kDa) and a Lachnospiraceae bacterium ND2006 type V CRISPR-Cas protein LbCpf1 (147 kDa) to the vector and found that the production of xylanase1 and LbCpf1 was as high as 0.69 and 0.49% of total soluble protein. Our result showed that IFT25P-IFT25-2AE system is more efficient to drive nuclear gene expression in C. reinhardtii than other conventionally used promoters, thus representing a novel efficient recombinant protein expression tool and has the potential to be scaled for commercial production of nuclear-encoded recombinant proteins of different sizes and origins in C. reinhardtii.