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Process intensification in biomanufacturing has attracted a great deal of interest in recent years. Manufacturing platform improvements leading to higher cell density and bioreactor productivity have been pursued. Here we evaluated a variety of intensified mammalian cell culture processes for producing monoclonal antibodies. Cell culture operational modes including fed-batch (normal seeding density or high seeding density with N-1 perfusion), perfusion, and concentrated fed-batch (CFB) were assessed using the same media set with the same Chinese Hamster Ovary (CHO) cell line. Limited media modification was done to quickly fit the media set to different operational modes. Perfusion and CFB processes were developed using an alternating tangential flow filtration device. Independent of the operational modes, comparable cell specific productivity (fed-batch: 29.4 pg/cell/day; fed-batch with N-1 perfusion: 32.0 pg/cell/day; perfusion: 31.0 pg/cell/day; CFB: 20.1 - 45.1 pg/cell/day) was reached with similar media conditions. Continuous media exchange enabled much higher bioreactor productivity in the perfusion (up to 2.29 g/L/day) and CFB processes (up to 2.04 g/L/day), compared with that in the fed-batch processes (ranging from 0.39 to 0.49 g/L/day), largely due to the higher cell density maintained. Furthermore, media cost per gram of antibody produced from perfusion was found to be highly comparable with that from fed-batch; and the media cost for CFB was the highest due to the short batch duration. Our experimental data supports the argument that media cost for perfusion process could be even lower than that in a fed-batch process, as long as sufficient bioreactor productivity is achieved. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:867-878, 2017.

Two dimensional material/semiconductor heterostructures offer alternative platforms for optoelectronic devices other than conventional Schottky and p-n junction devices. Herein, we use MoS 2 /GaAs heterojunction as a self-driven photodetector with wide response band width from ultraviolet to visible light, which exhibits high sensitivity to the incident light of 635 nm with responsivity as 446 mA/W and detectivity as 5.9×10 13 Jones (Jones = cm Hz 1/2 W -1 ), respectively. Employing interface design by inserting h-BN and photo-induced doping by coveringSi quantum dots on the device, the responsivity is increased to 419 mA/W for incident light of 635 nm. Distinctly, attributing to the low dark current of the MoS 2 /h-BN/GaAs sandwich structure based on the self-driven operation condition, the detectivity shows extremely high value of 1.9 × 10 14 Jones for incident light of 635 nm, which is higher than all the reported values of the MoS 2 based photodetectors.

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Heteronanostructures have attracted intensive attention due to their electronic coupling effects between distinct components. Despite tremendous advances of nanostructure fabrication, combining independent polymorphs by forming heterojunction is still challenging but fascinating, such as copper sulfides (CuS), exhibiting varying band gaps and crystal structures with various stoichiometries. Herein, self-coupled CuS polymorphs (CuS-CuS) by a facile one-pot chemical transformation route have been reported for the first time. Unprecedentedly, a manganous precursor plays a crucial role in inducing and directing the formation of such a dumbbell-like architecture, which combines 1D CuS with 2D CuS. During the transformation, Mn ions mediate the Cu ions diffusion and phase conversion process particularly. Furthermore, this self-coupled polymorphic structure exhibits significantly enhanced photoelectrochemical properties compared with the individual CuS nanocrystals and CuS nanoplates, originating from the unique heterointerfaces constructed by intrinsic band alignment and the enhanced contact between high conductivity hexagonal planes and the working electrode revealed by density functional theory (DFT) calculations. So we anticipate this emerging interfacial charge separation could provide useful hints for applications in optoelectronic devices or photocatalysis.