A reversible implantable memristor for health monitoring applications.

Conventional implantable electronics based on von Neumann architectures encounter significant limitations in computing and processing vast biological information due to computational bottlenecks. The memristor with integrated memory-computing and low power consumption offer a promising solution to overcome the computational bottleneck and Moore's law limitations of traditional silicon-based implantable devices, making them the most promising candidates for next-generation implantable devices. In this work, a highly stable memristor with an Ag/BaTiO3/MnO2/FTO structure was fabricated, demonstrating retention characteristics exceeding 1200 cycles and endurance above 1000 s. The device successfully exhibited three-stage responses to biological signals after implantation in SD (Sprague-Dawley) rats. Importantly, the memristor perform remarkable reversibility, maintaining over 100 cycles of stable repetition even after extraction from the rat. This study provides a new perspective on the biomedical application of memristors, expanding the potential of implantable memristive devices in intelligent medical fields such as health monitoring and auxiliary diagnostics.

Screening of multi-copy mannanase recombinants of Pichia pastoris based on colony size.

Pichia pastoris pGAP (glyceraldehyde dehydrogenase promoter) expression system was widely used for the expression and production of heterologous proteins. Screening multi-copy recombinants was an effective strategy to improve the heterologous protein production in P. pastoris. Because multiple gene insertion events occurred with a low frequency, hundreds to thousands of antibiotic-resistance recombinants need to be screened. The common way of improving screening efficiency was to increase antibiotic concentration in screening plates. Here we developed a screening method by selecting small colonies from low-concentration antibiotic screening plates. This strategy greatly improved the probability of obtaining multi-copy mannanase gene (man) recombinants and it could replace the common strategy by increasing antibiotic concentration in screening plates. The further study in liquid shake flask cultures revealed that cell concentrations, growth rates and substrate consumption rates of recombinants gradually decreased with the increase in man copy number. This indicated that such a screening strategy was effective to screen multi-copy recombinants based on colony size.

Development of an industrial medium and a novel fed-batch strategy for high-level expression of recombinant ß-mananase by Pichia pastoris.

An industrial medium, Corn Steep Liquor Powder Dextrose (CSD medium) was developed for constitutive expression of recombinant ß-mananase by Pichia pastoris. The ß-mananase activity (513 U/mL) with CSD medium was 1.64- and 2.5-fold higher than with YPD and BSM in shaken flasks. The ß-mananase productivity with CSD medium was 61.0 U/mL h, which was 1.7- and 2.5-fold higher than with YPD and BSM in a 5-L fermenter based on a novel fed-batch strategy combining the real-time exponential feed mode with the DO-stat feed mode. The ß-mananase activity, dry cell weight and the recombinant enzyme reached up to 5132 U/mL, 110.0 g/L and 4.50 g/L after 50 h cultivation in a 50-L fermenter. The high efficient expression of recombinant ß-mananase by P. pastoris indicated that CSD medium and the novel fed-batch strategy have great potential for the production of recombinant ß-mananase in industrial fermentation.