Organic Polymer-based Monoliths Research Articles

Various Strategies in Post-Polymerization Functionalization of Organic Polymer-Based Monoliths Used in Liquid Phase Separation Techniques.

This review article is aimed at summarizing the various strategies that have been developed so far for post-polymerization functionalization (PPF) of organic polymer-based monoliths used in liquid phase separation techniques, namely HPLC at all scales and capillary electrochromatography (CEC). The reader will find the organic reactions performed on monolithic columns for grafting the chromatographic ligands needed for solving the separation problems on hand. This process involves therefore the fabrication of template monoliths that carry reactive functional groups to which chromatographic ligands can be covalently attached in a post-polymerization kind of approach. That is, the template monolith that has been optimized in terms of pore structure and other morphology can be readily modified and tailor made on column to fit a particular separation. The review article will not only cover the various strategies developed so far but also describe their separation applications. To the best of our knowledge, this review article will be the first of its kind.

Eco-friendly production of metal nanoparticles immobilised on organic monolith for pepsin extraction

Abstract Polymer monoliths modified by using nanoparticles (NPs) integrate high NP specific surface area with different monolith surface chemistry and high porosity. As a result, they have extensive applications within different fields, whereas nanomaterial-functionalised porous polymer monoliths have elicited considerable interest from investigators. This study is aimed at fabricating organic polymer-based monoliths from polybutyl methacrylate-co-ethylenedimethacrylate (BuMA-co-EDMA) monoliths prior to immobilization of gold or silver metal on the pore surface of the monoliths using reducing reagent (extracts of lemon peels). This was intended to denote a sustainable technique of immobilizing nanoparticles that are advantageous over physical and chemical techniques because it is safe in terms of handling, readily available, environmentally friendly, and cheap. Two different methods were used in the study to effectively immobilize nanoparticles on monolithic components. The outcomes showed that soaking the monolith rod in the prepared nano solution directly and placing it within ovens at temperatures of 80°C constituted the most effective method. Characterisation of the fabricated monolith was undertaken using SEM/EDX analysis, UV-vis. spectra analysis, and visual observation. The SEM analysis showed that nanoparticles were extensively immobilised on the surface polymers. Another peak was attained through EDX analysis, thus confirming the Au atom existence at 2.83% alongside another peak that proved the Ag atom existence at 1.92%. The fabricated components were used as sorbents for purifying protein. The ideal performance was achieved using gold nanoparticles (GNPs) immobilised organic monolith that attained a greater pepsin extraction recovery compared to silver nanoparticles (SNPs) immobilised organic monoliths alongside bare organic-based monolith.

Organic polymer-based monolithic stationary phases with incorporated nanostructured materials for HPLC and CEC.

This review article is concerned with the recent advances made in the field of organic polymer-based monoliths with incorporated nanostructured materials (NSMs) for use in liquid chromatography and capillary electrochromatography. It covers the pertinent literature published over the last 7-8 years with a total of 56 references. The present article has two distinct parts: one major part encompassing "traditional" organic polymer-based monoliths modified with NSMs and a minor part on cryogels modified with NSMs.

A rapid synthetic method for organic polymer-based monoliths in a room temperature ionic liquid medium via microwave-assisted vinylization and polymerization

In this communication, we report a very efficient method of manufacturing polymer-based monolith in an ionic liquid reaction medium via microwave-assisted vinylization and polymerization. This novel approach took only 10 min to complete the whole process.

Application of Monolithic Stationary Phases in Solid-Phase Extraction and Pharmaceutical Analysis

Development of new style chromatographic packing materials and improvement of their performance are important in the study of pharmaceutical analysis. Monoliths are separation media in a format that can be compared with a single large particle that does not contain the interparticular voids typical of packed beds. In recent years, monolithic supports as stationary phases in high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) have gained significant interest due to their ease of preparation, high reproducibility, versatile surface chemistries and fast mass transport. Generally, depending on the nature of the monolithic material, organic polymer-based monolithic columns and silica-based monolithic columns can be identified. The silica monoliths prepared from tetraalkoxysilane by a sol – gel method can provide either micrometer-size through-pores or high specific surface areas and can be well suited for small molecules in HPLC modes. Organic polymer-based monoliths including monolithic molecularly imprinted polymers have been applied not only in separation and analysis of biomacromolecules, but also in treatments of the samples before injected into the chromatograph in biological fluids because it allows the simultaneous removal of matrix compounds and preconcentration of the analytes. The most commonly reported organic polymers are based on polystyrenes, polymethacrylates and polyacrylamides. Capillary electrophoresis with both organic polymer-based and silica-based monolithic columns has also been used for the separation of small molecules. This review summarizes the current achievements and their application of organic polymer-based monolithic columns and silica-based monolithic columns for both HPLC and CE in solid-phase extraction (SPE) and pharmaceutical analysis. The potential of these columns is demonstrated with separations involving various drugs in different chromatographic modes. Keywords: Monolithic Column, Solid-phase Extraction, Pharmaceutical Analysis, Separation, HPLC, CEC

Analyses of synthetic antioxidants by capillary electrochromatography using poly(styrene–divinylbenzene–lauryl methacrylate) monolith

In this study, several organic polymer-based monoliths prepared by single step in situ copolymerization of styrene- and methacrylate ester-based monomers (styrene (S), divinylbenzene (DVB) and lauryl methacrylate (LMA)) were developed as stationary phases of capillary electrochromatography (CEC) for the analyses of synthetic antioxidants. These monoliths were characterized by examining the SEM image, IR spectrum, and measuring the pore size, surface area, conversion yield, and thermal decomposition temperature. The polymerization procedure was optimized by varying the reaction temperature, the reaction time, and the LMA–styrene ratio. The LMA–styrene ratio had the most significant influence on the peak symmetry of butylated hydroxyanisole (BHA) and 2, 6-di- tert-butyl-4-methyl phenol (BHT), the latter being greatly affected by excessive peak tailing in the poly(S–DVB) monolith. It showed that the interaction between the poly(S–DVB) monolith and the antioxidant (BHT or BHA) was significantly altered by the insertion of LMA. Compared with the best HPLC and CE methods previously reported, this proposed CEC method provides a comparable separation ability for the five antioxidants analyzed. This study demonstrates that the potentiality of poly(S–DVB–LMA) monolith as stationary phase, especially for CEC system, because of high thermal stability and good column reproducibility.

Application and development of monolithic stationary phases for HPLC in pharmaceutical analysis and separation

In recent years, monolithic supports as stationary phases in high-performance liquid chromatography (HPLC) have become a rapidly burgeoning field. This review summarizes the current achievements and their application in pharmaceutical analysis and separation. One kind is the silica monoliths prepared from tetraalkoxysilane by a sol-gel method with either micrometer-size through-pores or high specific surface areas and well suited for small molecules in HPLC modes. The other kind is the organic polymer-based monoliths including monolithic molecularly imprinted polymers in treatments of the samples before injected into the chromatograph in biological fluids. The analytical potential of these columns is demonstrated with separations involving various drugs in different chromatographic modes.

Polyhedral Oligomeric Silsesquioxane as a Cross-linker for Preparation of Inorganic−Organic Hybrid Monolithic Columns

An inorganic-organic hybrid monolithic capillary column was synthesized via thermal free radical copolymerization within the confines of a capillary using a polyhedral oligomeric silsesquioxane (POSS) reagent as the inorganic-organic hybrid cross-linker and a synthesized long carbon chain quaternary ammonium methacrylate of N-(2-(methacryloyloxy)ethyl)-dimethyloctadecylammonium bromide (MDOAB) as the organic monomer. The preparation process was as simple as pure organic polymer-based monolithic columns instead of using POSS as the nanosized inorganic-organic hybrid blocks (cross-linker) of the monolithic matrix. The pore properties and permeability could be tuned by the composition of the polymerization mixture. The characterization and evaluation results indicated that the synthesized MDOA-POSS hybrid monolith possessed the merits of organic polymer-based monoliths and silica-based monoliths with good mechanical and pH (pH 1-11) stabilities, which may be attributed to the incorporation of the rigid nanosized silica core of POSS. Column efficiencies of 223 000 and 50 000 N/m were observed in capillary electro-driven chromatography (CEC) and mu-HPLC, respectively. Peptides and standard proteins were baseline separated by this hybrid column in CEC and mu-HPLC, respectively, as well. The separation of bovine serum albumin (BSA) tryptic digest was also attempted to show its potential application in proteome analysis.

A strong inorganic acid‐initiated methacrylate polymerization strategy for room temperature preparation of monolithic columns for capillary electrochromatography

A facile strong inorganic acid-initiated methacrylate polymerization strategy was developed for fabricating monolithic columns at room temperature. The prepared monoliths were characterized by FTIR spectrometry, mercury intrusion porosimeter and SEM, while their performance was evaluated by CEC for the separation of various types of compounds including alkyl benzenes, polycyclic aromatic hydrocarbons, nonsteroidal anti-inflammatory drugs, anilines, and nitrophenol isomers. The column-to-column and batch-to-batch reproducibility for the prepared monoliths in terms of the RSD of EOF flow velocity, retention factor, and the minimum plate height of naphthalene ranged from 3.4 to 12.4%. The fabricated monoliths gave excellent performance for the separation of the test neutral compounds with the theoretical plates of 170,000-232,000 plates per meter for thiourea, and 77,400-112,300 plates per meter for naphthalene. The proposed strong inorganic acid-initiated methacrylate polymerization strategy is a promising alternative for fabricating organic polymer-based monoliths.

Comparison of monolithic approaches for enantioselective capillary electrochromatography involving cyclodextrins

The access to CD-modified monoliths for enantiomeric separation by CEC can be divided into two main approaches. (i) Silica-based monoliths, prepared by either a sol-gel process or by sintering of silica particles, are modified after fabrication by coating with a CD selector. Alternatively the fusion of CD functionalized silica particle via gluing is feasible. (ii) Rigid or homogeneous organic polymer-based monoliths, prepared by polymerization of organic monomers in the presence of a porogen, are modified with the CD selector either by copolymerization or by physical incorporation into the continuous bed.

Less common applications of monoliths: I. Microscale protein mapping with proteolytic enzymes immobilized on monolithic supports

This review summarizes the recent contributions to the rapidly growing area of immobilized enzymes employing both silica and synthetic polymer-based monoliths as supports. Focus is mainly on immobilized proteolytic enzyme reactors designed for studies in proteomics. Porous monoliths emerged first as a new class of stationary phases for HPLC in the early 1990s. Soon thereafter, they were also used as supports for immobilization of proteins and preparation of both stationary phases for bioaffinity chromatography and enzymatic reactors. Organic polymer-based monoliths are typically prepared using a simple molding process carried out within the confines of a "mold" such as chromatographic column or capillary. Polymerization of a mixture comprising monomers, initiator, and porogenic solvent affords macroporous materials. In contrast, silica-based monoliths are first formed as a rigid rod from tetraalkoxysilane in the presence of PEG and subsequently encased with a plastic tube. Both types of monolith feature large through-pores that enable a rapid flow-through. Since all the solutions must flow through the monolith, the convection considerably accelerates mass transfer within the monolith. As a result, reactors including enzyme immobilized on monolithic support exhibit much higher activity compared to the reactions in solution.