Rational design of agarose/dextran composite microspheres with tunable core-shell microstructures for chromatographic application

A new type of core-shell microsphere was prepared by a pre-crosslinking method, consisting of cross-linked agarose microspheres as the core and agarose-dextran as the shell. After optimizing the preparation process, the microspheres with a uniform particle size were obtained and characterized using cryo-scanning electron microscopy to determine their surface and cross-sectional morphology. Results from flow rate-pressure and chromatographic performance tests showed that the core-shell agarose microspheres were supported by the core microspheres and composed of composite polysaccharides, forming an interpenetrating polymer network structure as a hard shell. The core-shell agarose microspheres showed a 300.5 % increase in linear flow rate compared to composite polysaccharide microspheres prepared from shell materials and a 141.5 % increase compared to 6 % agarose microspheres. Additionally, the large pore structure of the shell combined with the fine pore structure of the core improved the material separation efficiency in the range of 0.1-2000 kDa. These findings suggest that core-shell natural polysaccharide microspheres have great potential as a separation chromatographic medium.

Characterization of the physical and weathering properties of low sulfur fuel oil (LSFO) and its spreading on water surface

Effective countermeasures against the marine pollution caused by spilled oil are enabled based on the understanding of its physical and weathering characteristics. In that sense, our knowledge of the newly enforced low-sulfur fuel oil (LSFO) needs to be secured urgently. First, we show that the oil viscosity increases with decreasing temperature, following the William-Landel-Ferry law developed for bunker oil. The meso-stable emulsion is achieved from the emulsion test, of which the viscosity is 10-100 times larger than the normal one. On the other hand, the portion of the evaporation of LSFO was insignificant (less than 3%), and thus, its effect on the oil properties is not substantial except the increase of the viscosity. In addition, we experimentally examine the spreading features (e.g., spreading area and rate) of LSFO on the water surface in the circulating water bath. We find that initially, the oil spreading area increases quite fast but saturates, of which the details are explained in terms of the driving and retarding forces involved in the spreading processes. Finally, considering the procured properties of the LSFO, we performed a numerical simulation of spreading LSFO on the water surface with a scale of hundred meters, which shows that our analysis can be extended to larger scales.

Simplified, Shear Induced Generation of Double Emulsions for Robust Compartmentalization during Single Genome Analysis

Drop microfluidics has driven innovations for high throughput, low input analysis techniques such as single-cell RNA-seq. However, the instability of single emulsion (SE) drops occasionally causes significant merging during drop processing, limiting most applications to single-step reactions in drops. Here, we show that double emulsion (DE) drops address this critical limitation and completely prevent drop contents from mixing. DEs show excellent stability during thermal cycling. More importantly, DEs undergo rupture into the continuous phase instead of merging, preventing content mixing and eliminating unstable drops from the downstream analysis. Due to the lack of drop merging, the monodispersity of drops is maintained throughout a workflow, enabling the deterministic manipulation of drops downstream. We also developed a simple, one-layer DE drop maker compatible with simple surface treatment using a plasma cleaner. The device allows for the robust production of single-core DEs at a wide range of flow rates and better control over the shell thickness, both of which have been significant limitations of conventional two-layer devices. This approach makes the fabrication of DE devices much more accessible, facilitating its broader adoption. Finally, we show that DE droplets eliminate content mixing and maintain compartmentalization of single virus genomes during PCR-based amplification and barcoding, while SEs mixed contents due to merging. With their resistance to content mixing, DE drops have key advantages for multistep reactions in drops, which is limited in SEs due to merging and content mixing.

Static-state particle fabrication via rapid vitrification of a thixotropic medium

Functional particles that respond to external stimuli are spurring technological evolution across various disciplines. While large-scale production of functional particles is needed for their use in real-life applications, precise control over particle shapes and directional properties has remained elusive for high-throughput processes. We developed a high-throughput emulsion-based process that exploits rapid vitrification of a thixotropic medium to manufacture diverse functional particles in large quantities. The vitrified medium renders stationary emulsion droplets that preserve their shape and size during solidification, and energetic fields can be applied to build programmed anisotropy into the particles. We showcase mass-production of several functional particles, including low-melting point metallic particles, self-propelling Janus particles, and unidirectionally-magnetized robotic particles, via this static-state particle fabrication process.

Improving vitamin D3 stability to environmental and processing stresses using mixed micelles

Deficiency of vitamin-D is prevalent globally and can lead to negative health consequences. The fat-soluble nature of vitamin-D, coupled with its sensitivity to heat, light and oxygen limits its incorporation into foods. Mixed micelles (MM) have potential to enhance bioavailability of vitamin-D. This study explores the stability of MM to food processing regimes and their ability to protect vitamin-D. Subjecting MM to a range of shearing speeds (8,000-20,500 rpm) and to high pressure processing (600 MPa, 120sec) resulted in no change in MM size (4.1-4.5 nm). MM improved the retention of vitamin-D following exposure to UV-C light, near UV/visible light, and heat treatment. MM suspensions protected vitamin-D over a four week storage period at refrigeration or freezer conditions. Overall MM show potential to protect vitamin-D from degradation encountered in food processing and storage and may be beneficial as a mechanism to fortify foods with vitamin-D.

High-throughput screening for high-efficiency small-molecule biosynthesis

Systems metabolic engineering faces the formidable task of rewiring microbial metabolism to cost-effectively generate high-value molecules from a variety of inexpensive feedstocks for many different applications. Because these cellular systems are still too complex to model accurately, vast collections of engineered organism variants must be systematically created and evaluated through an enormous trial-and-error process in order to identify a manufacturing-ready strain. The high-throughput screening of strains to optimize their scalable manufacturing potential requires execution of many carefully controlled, parallel, miniature fermentations, followed by high-precision analysis of the resulting complex mixtures. This review discusses strategies for the design of high-throughput, small-scale fermentation models to predict improved strain performance at large commercial scale. Established and promising approaches from industrial and academic groups are presented for both cell culture and analysis, with primary focus on microplate- and microfluidics-based screening systems.