Photo-polymerized lauryl methacrylate monolithic columns for CEC using lauroyl peroxide as initiator

A protocol for fabrication of polymer monolithic capillary columns and tuning the morphology targeting high-resolution bioanalysis in gradient-elution liquid chromatography

Polymer monolithic stationary phases are designed as a continuous interconnected globular material perfused by macropores. Like packed column, where separation efficiency is related to particle diameter, the efficiency of monoliths can be enhanced by tuning the size of both the microglobules and macropores. This protocol described the synthesis of poly(styrene-co-divinylbenzene) monolithic stationary phases in capillary column formats. Moreover, guidelines are provided to tune the macropore structure targeting high-throughput and high-resolution monolith chromatography. The versatility of these columns is exemplified by their ability to separate tryptic digests, intact proteins, and oligonucleotides under a variety of chromatographic conditions. The repeatability of the presented column fabrication process is demonstrated by the successful creation of 12 columns in three different column batches, as evidenced by the consistency of retention times (coefficients of variance [c.v.] = 0.9%), peak widths (c.v. = 4.7%), and column pressures (c.v. = 3.1%) across the batches.

Selection and characterization of DNA aptamers for highly selective recognition of the major allergen of olive pollen Ole e 1

In this study, single-stranded DNA aptamers with binding affinity to Ole e 1, the major allergen of olive pollen, were selected using systematic evolution of ligands by exponential enrichment (SELEX) method. Binding of the aptamers was firstly established by enzyme-linked oligonucleotide assay (ELONA) and aptaprecipitation assays. Additionally, aptamer-modified monolithic capillary chromatography was used in order to evaluate the recognition of this allergenic protein against other non-target proteins. The results indicated that AptOle1#6 was the aptamer that provided the highest affinity for Ole e 1. The selected aptamer showed good selective recognition of this protein, being not able to retain other non-target proteins (HSA, cyt c, and other pollen protein such as Ole e 9). The feasibility of the affinity monolithic column was demonstrated by selective recognition of Ole e 1 in an allergy skin test. The stability and reproducibility of this monolithic column was suitable, with relative standard deviations (RSDs) in retention times and peak area values of 7.8 and 9.3%, respectively (column-to-column reproducibility). This is the first study that describes the design of an efficient DNA aptamer for this relevant allergen.

Characterization and comparison of methacrylic acid with 2-acrylamido-2-methyl-1-propanesulfonic acid in the preparation of monolithic column for capillary electrochromatography

Butyl methacrylate (BMA)-ethylene dimethacrylate (EDMA)-methacrylic acid (MAA) and BMA-EDMA-2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) monolithic columns were prepared by varying the percentage of ionic monomers for capillary electrochromatography. Monolithic columns with a higher content of ionic monomers provided better column efficiency, and the performance of BMA-EDMA-MAA monoliths was better than BMA-EDMA-AMPS. To characterize and optimize BMA-EDMA-MAA monoliths, the effects of the content of cross-linker and the total monomer in the polymerization mixture on column performance were also studied. Plate heights of 8.2 µm for the unretained solute (thiourea) and 12.6 µm for the retained solute (naphthalene) were achieved with a monolithic column using 2.5% MAA (Column I).

Porous polymer monoliths: amazingly wide variety of techniques enabling their preparation

The porous polymer monoliths went a long way since their invention two decades ago. While the first studies applied the traditional polymerization processes at that time well established for the preparation of polymer particles, creativity of scientists interested in the monolithic structures has later led to the use of numerous less common techniques. This review article presents vast variety of methods that have meanwhile emerged. The text first briefly describes the early approaches used for the preparation of monoliths comprising standard free radical polymerizations and includes their development up to present days. Specific attention is paid to the effects of process variables on the formation of both porous structure and pore surface chemistry. Specific attention is also devoted to the use of photopolymerization. Then, several less common free radical polymerization techniques are presented in more detail such as those initiated by gamma-rays and electron beam, the preparation of monoliths from high internal phase emulsions, and cryogels. Living processes including stable free radicals, atom transfer radical polymerization, and ring-opening metathesis polymerization are also discussed. The review ends with description of preparation methods based on polycondensation and polyaddition reactions as well as on precipitation of preformed polymers affording the monolithic materials.