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The present work evaluated for the first time the use of continuous slug flow crystallizer (CSFC) in bulk seeded protein crystallization, using lysozyme (LYZ) as the model protein. LYZ crystals pre-prepared in batch crystallizer were used as seeds. The crystallization was performed at supersaturation level below the metastable-zone-limit. The resultant crystal size distribution (CSD), CSD's reproducibility, LYZ's bioactivity, and crystallization efficiency as characterized by the space-time-yield (STY, mg/h·L) were determined. The results showed that the CSFC's performance was governed by the flowrate, where a trade-off existed between crystal quality and crystallization efficiency upon varying the flowrate. At low flowrates, which reduced the shear rate and prolonged the residence time, well-defined large tetragonal crystals were produced attributed to suppressed secondary nucleation and extended crystal growth, but low STY due to difficulty in transporting the seeds/products crystals. Higher flow rates led to higher STY, but increased production of small non-tetragonal crystals that formed agglomerates. Compared to batch crystallizer, the CSFC produced LYZ crystals of similar average size, morphology, and bioactivity, but with roughly 50% lower STY, as the batch's high-shear environment promoted secondary nucleation, hence higher crystallization rate. The CSD's width and reproducibility was nevertheless significantly improved in CSFC. Ministry of Education (MOE) The authors would like to acknowledge the funding from Ministry of Education Singapore under Academic Research Fund Tier 1RG82/20 (2021).

Continuous crystallization has been proposed as the downstream processing step for the purification of pharmaceutical proteins aimed at alleviating the manufacturing bottleneck caused by the limitations of chromatography-based operations at high upstream production titers. Herein we reviewed the current state of research in continuous protein crystallization from which future research directions were identified. While the benefits of batch-to-continuous manufacturing transformation have been long established, progress in continuous protein crystallization lags behind its small-molecule counterpart. The reasons are because the challenging nature of protein crystallization, even when performed in the batch platform, and the lack of well-understood proteins available for thorough study. Nevertheless, successful batch-to-continuous transformations in both mixed-suspension-mixed-product-removal crystallizer and tubular crystallizers (i.e. slug flow, oscillatory baffled flow) have been demonstrated using lysozyme or monoclonal antibody as the model protein. Compared to the batch platform, the continuous platform produces comparable crystallization yield but with higher production capacity (g/h). Strategies to optimize the crystallizer's performance based on modeling and simulation results are also available. Future research should (1) study a wider range of proteins with impurities incorporated in the raw material streams, and (2) adopt advancements in continuous crystallization of small-molecule pharmaceuticals to improve the crystal quality and yield. Ministry of Education (MOE) The authors would like to thank the Ministry of Education Singapore for funding this work (Grant No. RG7/17 PI: Kunn Hadinoto Ong).

Ideal metal-organic frameworks (MOFs) are those have not only significant adsorption separation performances but also excellent vapor and/or thermal stability. In this work, a calcium-based metal-organic framework with high vapor-stability and thermostability, Ca(squarate), was prepared using readily available precursor (CaCO3) and squaric acid as starting materials by hydrothermal method. Characterization techniques including PXRD, TGA and BET surface area analysis reveal that this MOF remains stable no matter whether it was soaked in water or exposed to air for as long as 2 weeks. Moreover, the studied MOF material is capable of discriminating C2 hydrocarbon molecules as it has an appropriate pore diameter around 3.4 A. Excellent efficient separation for C2H2/C2H4 mixture (50:50, v/v) with an adsorption selectivity of 8.1 was realized at room temperature and ambient pressure, on the other hand, it also displayed a good separation performance for C2H4/C4H6 mixture (50:50, v/v) with an adsorption selectivity of 5.9. Furthermore, adsorption mechanism of C2 hydrocarbons in this framework was investigated by the DFT-D calculation. The results revealed that this framework discriminated light hydrocarbons as a result of different interaction strength between hydrocarbons and framework that mainly arise from π-π interactions.

Mg-MOF-74 is one of the most well-known metal–organic frameworks (MOFs) and has been widely studied for gas adsorption and separation. Nevertheless, employment of original Mg-MOF-74 in powder form inevitably leads to a high pressure drop across column and even dust pollution in practical application. In this work, we molded powder Mg-MOF-74 into extrudates and tested its performance on adsorptive separation of ethylene/ethane mixture for the first time, taking commercialized benchmark 13X zeolite as comparison. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area measurements, and thermal gravimetric analysis (TGA) were performed to characterize the transformed samples, and adsorption equilibrium of ethylene and ethane on molded Mg-MOF-74 were measured at 273 and 298 K and pressure up to 1 bar. The potential industrial application of molded Mg-MOF-74 was examined through breakthrough and regeneration experiments, revealing that molded Mg-MOF-74 was feasible and stable ...

Fluorescent materials play an extremely important role in understanding the microbiological world. New fluorescent materials which have good photophysical properties, low cytotoxicity, and multi-channel fluorescent imaging capability are still urgently needed, even though many kinds of fluorescent materials have already been synthesized. In this work, a new polythiophene derivative (PT-OH-PPR) modified with a porphyrin group in its side chain was designed and fabricated through FeCl3 oxidative polymerization. The obtained PT-OH-PPR has wide absorption and emission spectral range, good water solubility and low cytotoxicity. Importantly it could be enriched in the cytoplasm of A549 cells and be excited by two excitation wavelengths (488 nm and 559 nm), which provides a promising application in dual-channel cell imaging.