Advanced Separation Techniques Research Articles

Microgravity Separation of Alginate Empty Capsules from Encapsulated Pancreatic Islets Using a Microfluidic System.

Although microencapsulated pancreatic islets have merits, such as ease of transplantation, viability and functionality improvement, and immune protection in vivo, the co-production of alginate empty capsules during the encapsulation of islets with alginate makes them unusable for biomedical application. In previous research, the removal of empty alginate capsules with high yield was achieved using density-gradient centrifugation. Here, we report advanced microgravity-based separation techniques in a microfluidic format for alginate empty capsules. The optimal separation conditions were mathematically evaluated using Stokes' law and the separation of the encapsulation product was accomplished. A microfluidic chip was designed with two inlets and two outlets at different elevations to mimic the vertical percoll gradient in density-gradient centrifugation. The separation of alginate empty capsules using microgravitational force resulted in effective separation of encapsulated islets from alginate empty capsules with more than 70% efficiency. Moreover, no loss of encapsulated islets was expected because the process is a one-pot separation, unlike the previous method. This type of microgravitational particle separation could be used both for the fractionization of heterogeneous encapsulated cells and to remove empty capsules.

A superamphiphobic coating with an ammonia-triggered transition to superhydrophilic and superoleophobic for oil-water separation.

Superhydrophilic and superoleophobic materials are very attractive for efficient and cost-effective oil-water separation, but also very challenging to prepare. Reported herein is a new superamphiphobic coating that turns superhydrophilic and superoleophobic upon ammonia exposure. The coating is prepared from a mixture of silica nanoparticles and heptadecafluorononanoic acid-modified TiO2 sol by a facile dip-coating method. Commonly used materials, including polyester fabric and polyurethane sponge, modified with this coating show unusual capabilities for controllable filtration of an oil-water mixture and selective removal of water from bulk oil. We anticipate that this novel coating may lead to the development of advanced oil-water separation techniques.

The role and importance of advances in separation techniques

The role and importance of advances in separation techniques

Simple and efficient separation of atomically precise noble metal clusters.

There is an urgent need for accessible purification and separation strategies of atomically precise metal clusters in order to promote the study of their fundamental properties. Although the separation of mixtures of atomically precise gold clusters Au25L18, where L are thiolates, has been demonstrated by advanced separation techniques, we present here the first separation of metal clusters by thin-layer chromatography (TLC), which is simple yet surprisingly efficient. This method was successfully applied to a binary mixture of Au25L18 with different ligands, as well as to a binary mixture of different cluster cores, Au25 and Au144, protected with the same ligand. Importantly, TLC even enabled the challenging separation of a multicomponent mixture of mixed-monolayer-protected Au25 clusters with closely similar chemical ligand compositions. We anticipate that the realization of such simple yet efficient separation technique will progress the detailed investigation of cluster properties.

Zeolitic Imidazolate Frameworks: Next‐Generation Materials for Energy‐Efficient Gas Separations

Industrial separation processes comprise approximately 10% of the global energy demand, driven largely by the utilization of thermal separation methods (e.g., distillation). Significant energy and cost savings can be realized using advanced separation techniques such as membranes and sorbents. One of the major barriers to acceptance of these techniques remains creating materials that are efficient and productive in the presence of aggressive industrial feeds. One promising class of emerging materials is zeolitic imidazolate frameworks (ZIFs), an important thermally and chemically stable subclass of metal organic frameworks (MOFs). The objectives of this paper are (i) to provide a current understanding of the synthetic methods that enable the immense tunability of ZIFs, (ii) to identify areas of success and areas for improvement when ZIFs are used as adsorbents, (iii) to identify areas of success and areas for improvement in ZIF membranes. A review is given of the state-of-the-art in ZIF synthesis procedures and novel ZIF formation pathways as well as their application in energy efficient separations.

Proteomics of the human pituitary tissue: bioanalytical methods and applications.

The pituitary is the central endocrine gland that plays complex regulatory roles in growth, reproduction and metabolism of the body. The human pituitary tissue proteome has been the target of a number of investigations that applied various combinations of advanced separation techniques, mass spectrometry, and bioinformatics tools. This review describes the main features of the bioanalytical workflows used in pituitary proteomics, and summarizes major applications in pituitary proteome mapping, differential protein expression profiling in health and disease, and discovery of post-translational modifications in pituitary proteins.

Autopilot: An Online Data Acquisition Control System for the Enhanced High-Throughput Characterization of Intact Proteins

The ability to study organisms by direct analysis of their proteomes without digestion via mass spectrometry has benefited greatly from recent advances in separation techniques, instrumentation, and bioinformatics. However, improvements to data acquisition logic have lagged in comparison. Past workflows for Top Down Proteomics (TDPs) have focused on high throughput at the expense of maximal protein coverage and characterization. This mode of data acquisition has led to enormous overlap in the identification of highly abundant proteins in subsequent LC-MS injections. Furthermore, a wealth of data is left underutilized by analyzing each newly targeted species as unique, rather than as part of a collection of fragmentation events on a distinct proteoform. Here, we present a major advance in software for acquisition of TDP data that incorporates a fully automated workflow able to detect intact masses, guide fragmentation to achieve maximal identification and characterization of intact protein species, and perform database search online to yield real-time protein identifications. On Pseudomonas aeruginosa, the software combines fragmentation events of the same precursor with previously obtained fragments to achieve improved characterization of the target form by an average of 42 orders of magnitude in confidence. When HCD fragmentation optimization was applied to intact proteins ions, there was an 18.5 order of magnitude gain in confidence. These improved metrics set the stage for increased proteome coverage and characterization of higher order organisms in the future for sharply improved control over MS instruments in a project- and lab-wide context.

Improving the Understanding of the Properties and Retention Behavior of Chemically Bonded Stationary Phases Employing Suspended-state HR/MAS NMR Spectroscopy

Molecular recognition processes are predicted to become the basis of all advanced separation techniques. In solution and recently also in suspension ligand-receptor interactions can be studied using methods of high-resolution (HR) suspended-state NMR spectroscopy, for example by employing the saturation transfer difference (STD) NMR technique. In this approach molecular recognition processes of (R) and (S)-flurbiprofen on different derivatized polysaccharide-based silica chiral stationary phases (CSP) typically used in high performance liquid chromatography (HPLC) have been investigated. In addition to chromatographic investigations suspended-state high-resolution/ magic angle spinning (HR/MAS) NMR measurement were performed. A separation of racemic flurbiprofen was obtained on two out of three CSP column materials under identical chromatographic conditions. Hence, we expected significant different binding affinities resulting in spatial interactions stabilizing one transient diastereomeric complex relative to the other. Due to these differences we used for screening purposes T1 relaxation time measurements and the saturation transfer difference (STD) NMR methodology to study the interaction strength between (R) and (S) enantiomers and the three CSP materials used. Thus, saturation transfer difference (STD) NMR experiments can provide valuable information for the design and implementation of novel, task-specific or tailored stationary phases.

Quality control of traditional Chinese medicines: a review

Traditional Chinese medicines (TCMs) are in great demand all over the world, especially in the developing world, for primary health care due to their superior merits such as low cost, minimal side effects, better cultural acceptability, and compatibility with humans. However, Chinese medicines consist of several herbs which may contain tens, hundreds, or even thousands of constituents. How these constituents interact with each other, and what the special active ones are, may be the biggest bottleneck for the modernization and globalization of TCMs. Valid methods to evaluate the quality of TCMs are therefore essential and should be promoted and be developed further through advanced separation and chromatography techniques. This paper reviews the strategies used to control the quality of TCMs in a progressive perspective, from selecting single or several ingredients as the evaluation marker, to using different kinds of chromatography fingerprint methods. In summary, the analysis and quality control of TCMs are developing in a more effective and comprehensive manner to better address the inherent holistic nature of TCMs.

Supercritical methodologies applied to the production of biopesticides: a review

Supercritical technologies are new, environmentally friendly, advanced separation techniques that have attracted the attention of both industry and academy in their aspirations of producing safer products with cleaner processes. In the field of biopesticides, supercritical fluids are being used in different stages, from the extraction of active ingredients from natural matrices to the encapsulation of blends during the formulation of the final commercial pesticide. This review summarizes different supercritical processes that arise in literature comprising supercritical fluid extraction, supercritical antisolvent fractionation or extraction, supercritical assisted atomization, particle from gas saturated solutions and supercritical solvent impregnation among others. The aim of this work is to give a general view of supercritical fluids in the field of biopesticides production, optimization and formulation, emphasizing in the extraction, fractionation and encapsulation and highlighting their importance when green, solvent free processes have to be designed.

Supercritical extraction and supercritical antisolvent fractionation of natural products from plant material: comparative results on Persea indica

Supercritical fluids (SCFs) are alternative solvents in the field of Green Chemistry that are being developed as advanced separation techniques due to their combined properties such as the penetrability of a gas and the solvent power of a liquid. These characteristics are used in the supercritical fluid extraction (SFE), where compounds of interest can be extracted after mixing a SCF as a solvent with a matrix in a pressurized vessel. Supercritical antisolvent fractionation (SAF) uses the SCF as antisolvent, allowing for the precipitation of insoluble compounds in the SCF-organic solution mixture. An updated overview of SFE and SAF of natural products is presented in this article. Additionally we compare the results of SFE, SAF and organic soxhlet extraction (OSE) of Persea indica, a Macaronesian paleoendemism with strong insecticidal components. The composition of the extracts was analyzed by HPLC-MS, showing in the SFE extracts as major components ryanodol, cinnzeylanol and alkyl-γ-lactones, with their abundance varying with the extraction conditions. On the other hand, the SAF allowed for the fractionation of a liquid solution to give a ryanodol enriched extract (31 % more ryanodol than the initial ethanolic solution). The antifeedant and postingestive effects of these extracts on Spodoptera littoralis showed that the SAF extracts were the most active followed by SFE and OSE and their different effects can be partially explained by their composition.

Protein Biomarkers for Traumatic and Ischemic Brain Injury: From Bench to Bedside

Stroke is the second leading cause of death worldwide and the third leading cause of death in the USA. A clinically useful biomarker for the diagnosis of stroke does not currently exist. Biomarkers could improve stroke care by allowing early diagnosis by non-expert clinical providers, serial monitoring of patients, and rapid assessment of severity of brain injury. With the introduction of highly advanced multidimensional separation techniques coupled with high throughput genomics/proteomics platforms, several components of the pathophysiological and biochemical pathways have been elucidated in the areas of brain trauma. A major outcome of these approaches is the discovery of biomarkers that would have important applications in diagnosis, prognosis, and even development of experimental neuroprotective drugs that have been used in different paradigms of brain injury. In this paper, we reviewed the recent advances of current and novel brain injury protein biomarkers and their utilities in different models of brain injury with an emphasis on stroke, an area that has been understudied. This will include the utility of neuroproteomics/neurosystems biology analysis as a novel discipline leading to the identification of novel biomarkers that can reach the pipeline of bench side. Additionally, an outline of biomarker-based management of traumatic brain injury and stroke patient assessments of therapeutic interventions has been included. Finally, comparison of current biomarker occurrence between preclinical models and biomarker data from human clinical studies for stroke has been summarized.

Antimicrobial potential of selected brown seaweeds from Vedalai coastal waters, Gulf of Mannar

Objective To evaluate the antimicrobial activity of Turbinaria conoides ( T. conoides) , Padina gymnospora ( P. gymnospora) and Sargassum tenerrimum against human bacterial and fungal pathogens. Methods The antimicrobial activities of the extracts against various organisms were tested by using disc diffusion method. Results The methanol extract showed the better result than the other extracts. Whereas, the strong antibacterial inhibition was noted in methanol extracts of P. gymnospora against Bacillus subtilus (26.33±1.86) and the mild inhibition of ethanol extracts from T. conoides against Klebsiella pneumoniae (2.33±0.51). Acetone extraction of P. gymnospora had strong antifungal inhibition against Cryptococcus neoformans (23.00±1.78), and acetone extract of T. conoides had mild inhibition against Aspergillus niger (3.00±0.89). Conclusions The seven different solvent extracts of seaweeds used in the present study have shown significant bacterial action. Further, a detailed study on the principle compound in the seaweeds which is responsible for antimicrobial activity is still needed and it can be achieved by using advanced separation techniques.

Sweeping–micellar electrokinetic chromatography for the simultaneous analysis of tricyclic antidepressant and β-blocker drugs in wastewater

The simultaneous analysis of tricyclic antidepressant (amitriptyline, clomipramine, doxepin and nortriptyline) and β-blocker (alprenolol, labetalol and propranolol) drugs in wastewater was developed via sweeping–micellar electrokinetic chromatography (MEKC) together with a simple liquid–liquid extraction step. For sweeping–MEKC, the amount of organic modifier in the separation electrolyte, the concentration of phosphoric acid in the sample matrix and the injection time of the sample were optimized. Sensitivity enhancements of up to 305-fold were achieved via sweeping. This allowed limits of detection (LOD) from 7 to 27ng/mL. The relative standard deviations of migration time, corrected peak area and peak height were less than 3.2%, 7.8% and 4.5%, respectively. Liquid–liquid extraction using dichloromethane as solvent afforded up to 21-fold enrichment of the drugs from spiked wastewater. No interference of the sample matrix was observed and recoveries were obtained in the range of 77–113% for all analytes except labetalol at three spiking levels of 16, 80 and 160ng/mL. Detection at the ng/mL level makes this simple, environmentally friendly and cost effective method competitive against recently reported methods using advanced liquid-phase separation techniques for monitoring similar drugs in wastewater.

Recent Advances in Separation Techniques for Trace Analysis of Iron and Steel

The determination of trace elements in iron and steel requires separation procedures to obtain the accurate and precise analytical results. The present review covers recent advances in separation techniques, including sorption, liquid–liquid extraction, precipitation, electrolysis, and volatilization.

Advanced Physical Separation Technology for Rare Metal Recycling

Physical separation is a technology to produce valuable metal powder from metals included in waste products. Many separation technologies are already used in conventional recycling processes for the recovery of common and precious metals. However, there are few separation technologies for the recovery of expensive metals such as tantalum and rare earth metals, which are called “rare-metals” in Japan, from small domestic appliances (SDAs). Advanced grinding, sorting and separation techniques have been investigated in our research group in order to recycle these metals from SDAs. Our representative studies for advanced physical separation processes are introduced, and the future picture of physical separation which we have painted is described in this report.

How to discover new antibiotics: harvesting the parvome

There is a dire need for new antibiotics; commercial discovery programs have essentially dried up and there is talk of 'a return to the pre-antibiotic era'. Natural products are an inexhaustible source of bioactive compounds (antibiotics among them), and recent technical advances such as DNA sequencing and bioinformatics offer new approaches to small molecule discovery. Given that nucleotide sequence studies of actinomycetes genomes reveal the presence of 20 or more pathways for the synthesis of bioactive compounds, 'mining' these sequences offers the potential of expanding the repertoire of antibiotics and other drugs. Combined with advanced chemical separation and characterization techniques, the construction of large chemically diverse libraries of bioactive compounds for therapeutic applications is a realistic near-term goal.

Structural elucidation of biologically active neomycin N‐octyl derivatives in a regioisomeric mixture by means of liquid chromatography/ion trap time‐of‐flight mass spectrometry

Structural elucidation of six regioisomers of mono-N-octyl derivatized neomycin is achieved using MS(n) (up to n = 4) on an ion trap time-of-flight (IT-TOF) instrument equipped with electrospray ionization. The mixture of six derivatized neomycin analogues was generated by reductive amination in a shotgun synthetic approach. In parallel to the liquid chromatography/mass spectrometry (LC/MS) detection, the antibacterial activity of the neomycin regioisomers was tested by post-column addition of buffer and bacterial inocula, subsequent microfractionation of the resulting mixture, incubation, and finally a chemiluminescence-based bioactivity measurement based on the production of bacterial ATP. The MS-based high-resolution screening approach described can be applied in medicinal chemistry to help in designing and producing new antibiotic substances, which is particularly challenging due to the high functionality of most antibiotic substances, therefore requiring advanced (hyphenated) separation and detection techniques for compound mixtures.

Orbit Determination of the Single-lined Spectroscopic Binaries by Using the Revised Hipparcos Intermediate Astrometric Data

By fitting the revised Hipparcos intermediate astrometric data (HIAD), we obtain the photocentric orbital solutions of some single-lined spectroscopic binaries (SB1s) in the 9th Catalogue of Orbits of Spectroscopic Binaries (SB9). For SB1s with relatively small magnitude difference between the two components, we find that the primary orbit is not a good approximation of the photocentric orbit in their orbit determination and suggest that future spectroscopic observations and advanced spectral separation techniques should be applied to these systems. In order to facilitate these future observations, we also estimate the full orbital solutions and provide the observational ephemerides. As an example, we give the result for HIP 113860.

Structure of the 30S translation initiation complex

Translation initiation, the rate-limiting step of the universal process of protein synthesis, proceeds through sequential, tightly regulated steps. In bacteria, the correct messenger RNA start site and the reading frame are selected when, with the help of initiation factors IF1, IF2 and IF3, the initiation codon is decoded in the peptidyl site of the 30S ribosomal subunit by the fMet-tRNA(fMet) anticodon. This yields a 30S initiation complex (30SIC) that is an intermediate in the formation of the 70S initiation complex (70SIC) that occurs on joining of the 50S ribosomal subunit to the 30SIC and release of the initiation factors. The localization of IF2 in the 30SIC has proved to be difficult so far using biochemical approaches, but could now be addressed using cryo-electron microscopy and advanced particle separation techniques on the basis of three-dimensional statistical analysis. Here we report the direct visualization of a 30SIC containing mRNA, fMet-tRNA(fMet) and initiation factors IF1 and GTP-bound IF2. We demonstrate that the fMet-tRNA(fMet) is held in a characteristic and precise position and conformation by two interactions that contribute to the formation of a stable complex: one involves the transfer RNA decoding stem which is buried in the 30S peptidyl site, and the other occurs between the carboxy-terminal domain of IF2 and the tRNA acceptor end. The structure provides insights into the mechanism of 70SIC assembly and rationalizes the rapid activation of GTP hydrolysis triggered on 30SIC-50S joining by showing that the GTP-binding domain of IF2 would directly face the GTPase-activated centre of the 50S subunit.