Enrichment and Recovery of Mammalian Cells from Contaminated Cultures Using Aqueous Two-Phase Systems

Emerging delivery systems based on aqueous two-phase systems: A review

The aqueous two-phase system (ATPS) is an all-aqueous system fabricated from two immiscible aqueous phases. It is spontaneously assembled through physical liquid-liquid phase separation (LLPS) and can create suitable templates like the multicompartment of the intracellular environment. Delicate structures containing multiple compartments make it possible to endow materials with advanced functions. Due to the properties of ATPSs, ATPS-based drug delivery systems exhibit excellent biocompatibility, extraordinary loading efficiency, and intelligently controlled content release, which are particularly advantageous for delivering drugs in vivo . Therefore, we will systematically review and evaluate ATPSs as an ideal drug delivery system. Based on the basic mechanisms and influencing factors in forming ATPSs, the transformation of ATPSs into valuable biomaterials is described. Afterward, we concentrate on the most recent cutting-edge research on ATPS-based delivery systems. Finally, the potential for further collaborations between ATPS-based drug-carrying biomaterials and disease diagnosis and treatment is also explored.

Magnetic chitin beads (MCB) coated with Vibrio cholerae reveals transcriptome dynamics in adult mice with a complex gut microbiota

Vibrio cholerae adapts to the host environment by altering gene expression. Because of the complexity of the gut microbiome, current in vivo V. cholerae transcriptome studies have focused on microbiota-undeveloped conditions, neglecting the interaction between the host's commensal gut microbiota and V. cholerae. In this study, we analyzed the transcriptome of fully colonized adult mice in vivo using V. cholerae coated-magnetic chitin beads (vcMCB). This provides a simple yet powerful method for obtaining high-quality RNA from V. cholerae during colonization in mice. The transcriptome of V. cholerae recovered from adult mice infected with vcMCB shows differential expression of several genes when compared to V. cholerae recovered from the infant mouse and infant rabbit model. Some of these genes were also observed to be differentially expressed in previous studies of V. cholera recovered from human infection when compared to V. cholerae grown in vitro. In particular, we confirmed that V. cholerae resists the inhibitory effects of low pH and formic acid from gut microbiota, such as Anaerostipes caccae and Dorea formicigenerans, by downregulating vc1080. We propose that the vc1080 product may protect V. cholerae from formic acid stress through a novel acid tolerance response mechanism. Transcriptomic data obtained using the vcMCB system provide new perspectives on the interaction between V. cholerae and the gut microbiota, and this approach can also be applied to studies of other pathogenic bacteria.

Advanced density-based methods for the characterization of materials, binding events, and kinetics

Investigations of the densities of chemicals and materials bring valuable insights into the fundamental understanding of matter and processes. Recently, advanced density-based methods have been developed with wide measurement ranges (i.e. 0-23 g cm^-3), high resolutions (i.e. 10^-6 g cm^-3), compatibility with different types of samples and the requirement of extremely low volumes of sample (as low as a single cell). Certain methods, such as magnetic levitation, are inexpensive, portable and user-friendly. Advanced density-based methods are, therefore, beneficially used to obtain absolute density values, composition of mixtures, characteristics of binding events, and kinetics of chemical and biological processes. Herein, the principles and applications of magnetic levitation, acoustic levitation, electrodynamic balance, aqueous multiphase systems, and suspended microchannel resonators for materials science are discussed.

Upgrading of bio‐separation and bioanalysis using synthetic polymers: Molecularly imprinted polymers (MIPs), cryogels, stimuli‐responsive polymers

Bio‐separation plays a crucial role in many areas. Different polymers are suitable for bio‐separation and are useful for applications in applications in both science and technology. Besides biopolymers, there are a broad spectrum of synthetic polymers with tailor‐made properties. The synthetic polymers are characterized by their charges, solubility, hydrophilicity/hydrophobicity, sensitivity to environmental conditions and stability. Furthermore, ongoing developments are of great interest on biodegradable polymers for the treatment of diseases. Smart polymers have gained great attention due to their unique characteristics especially emphasizing simultaneously changing their chemical and physical property upon exposure to changes in environmental conditions. In this review, methodologies applied in bio‐separation using synthetic polymers are discussed and efficient candidates are focused for the construction of synthetic polymers.

On-the-Fly Phase Transition and Density Changes of Aqueous Two-Phase Systems on a Centrifugal Microfluidic Platform

This paper describes on-the-fly physical property changes of aqueous two-phase systems (ATPS) in microfluidic devices. The properties and phases of the ATPS are modulated on-demand by using a centrifugal microfluidic device filled with poly(ethylene glycol) (PEG) and dextran (DEX) solutions. By use of the centrifugal force and active pneumatic controls provided by a centrifugal microfluidic platform (CMP), PEG-DEX mixtures are manipulated and processed inside simple thermoplastic microfluidic devices. First, we experimentally demonstrate an on-chip ATPS transition from two phases to a single phase and vice versa by dynamically changing the concentration of the solution to bring ATPS across the binodal curve. We also demonstrate a density modulation scheme by introducing an ATPS solution mixed with sodium diatrizoate hydrate, which allows to increase the liquid density. By adding precisely metered volumes of water, we spontaneously change the density of the solution on the CMP and show that density marker microbeads fall into the solution according to their corresponding densities. The measured densities of ATPS show a good agreement with densities of microbeads and analytical plots. The results presented in this paper highlight the tremendous potential of CMPs for performing complex on-chip processing of ATPS. We anticipate that this method will be useful in applications such as microparticle-based plasma protein analysis and blood cell fractionation.

Magnetic Levitation in Chemistry, Materials Science, and Biochemistry

All matter has density. The recorded uses of density to characterize matter date back to as early as ca. 250 BC, when Archimedes was believed to have solved "The Puzzle of The King's Crown" using density.^[1] Today, measurements of density are used to separate and characterize a range of materials (including cells and organisms), and their chemical and/or physical changes in time and space. This Review describes a density-based technique-magnetic levitation (which we call "MagLev" for simplicity)-developed and used to solve problems in the fields of chemistry, materials science, and biochemistry. MagLev has two principal characteristics-simplicity, and applicability to a wide range of materials-that make it useful for a number of applications (for example, characterization of materials, quality control of manufactured plastic parts, self-assembly of objects in 3D, separation of different types of biological cells, and bioanalyses). Its simplicity and breadth of applications also enable its use in low-resource settings (for example-in economically developing regions-in evaluating water/food quality, and in diagnosing disease).

Purification of Functional Human TRP Channels Recombinantly Produced in Yeast

(1) Background: Human transient receptor potential (TRP) channels constitute a large family of ion-conducting membrane proteins that allow the sensation of environmental cues. As the dysfunction of TRP channels contributes to the pathogenesis of many widespread diseases, including cardiac disorders, these proteins also represent important pharmacological targets. TRP channels are typically produced using expensive and laborious mammalian or insect cell-based systems. (2) Methods: We demonstrate an alternative platform exploiting the yeast Saccharomyces cerevisiae capable of delivering high yields of functional human TRP channels. We produce 11 full-length human TRP members originating from four different subfamilies, purify a selected subset of these to a high homogeneity and confirm retained functionality using TRPM8 as a model target. (3) Results: Our findings demonstrate the potential of the described production system for future functional, structural and pharmacological studies of human TRP channels.

Experimental and Theoretical Validation of System Variables That Control the Position of Particles at the Interface of Immiscible Liquids

We construct a mathematical model describing the equilibrium flotation height of a spherical particle at the interface of immiscible liquids. The behavior of such a system depends on several experimentally measurable parameters, which include surface tensions, densities of all phases, and system scale. These parameters can be absorbed into three quantities that entirely determine the equilibrium position of the particle: the contact angle between the interface and particle, the Bond number, and the ratio of particle buoyant density to liquid phase densities-a new, dimensionless number that we introduce here. This experimentally convenient treatment allows us to make predictions that apply generally to the large parameter space of interesting systems. We find the model is in good agreement with experiments for particle size and interfacial tension spanning 3 orders of magnitude. We also consider the low interfacial tension case of aqueous two-phase systems (ATPSs) theoretically and experimentally. Such systems are more sensitive to changes in density than higher-tension aqueous/organic two-phase systems; we experimentally demonstrate that a millimeter-sized bead in an ATPS can be controllably positioned with between 5.9 and 95.1% of its surface area exposed to the bottom phase, whereas the same bead in an aqueous/organic system is limited to a range of 18.2-61.6%. Finally, we discuss the potential for wettability-based control for micron length-scale particles, which are not sensitive to changes in density. Our results can be used to simply define the experimentally controllable parameters that affect the equilibrium position and the length scales of a particle over which such parameters can be effectively tuned. A complete understanding of these properties is important for a number of applications including colloidal self-assembly and chemical patterning (e.g., formation of desymmetrized or Janus particles). By considering ATPSs, we broaden the potential uses to biological applications such as cell separation and interfacial tissue assembly.