Preparation of macroporous monoliths based on epoxy-bearing hydrophilic terpolymers and applied for affinity separations

Mono-PEGylated lysozyme purification with increased productivity and isomer differentiation through heparin monolith chromatography

PEGylated protein purification with the required quality attributes has represented a bioengineering challenge and Affinity Monolith Chromatography (AMC) has never been exploited for this goal. This work reports the generation of a heparin-modified affinity monolith disk by reductive alkylation with raised ligand density for its use as chromatographic support in the separation of lysozyme PEGylation reactions (LPRs) with three different PEG sizes (1, 20 and 40 kDa). For immobilized heparin determination a modified toluidine colorimetric assay adapted to microplate format was proposed. The heparin modified-disk was able to differentiate positional isomers of 20 kDa mono-PEGylated lysozyme at neutral pH using a salt linear gradient. Identity of PEG-conjugates was verified by SDS-PAGE and positional isomers were partially characterized by peptide mapping mass spectrometry. 20 kDa mono-PEGylated lysozyme conjugate purity (99.69 ± 0.05%) was comparable with traditional chromatographic methods while productivity (0.0964 ± 0.0001 mg/mL*min) was increased up to 6.1 times compared to that obtained in heparin packed-bed affinity chromatography procedures. The proposed AMC method represents a reliable, efficient, easy-handling, fast and single-step operation for the analysis or preparative isolation of PEGylated proteins containing a heparin binding domain.

Affinity monolith chromatography: A review of general principles and recent developments

Affinity monolith chromatography (AMC) is a liquid chromatographic technique that utilizes a monolithic support with a biological ligand or related binding agent to isolate, enrich, or detect a target analyte in a complex matrix. The target-specific interaction exhibited by the binding agents makes AMC attractive for the separation or detection of a wide range of compounds. This article will review the basic principles of AMC and recent developments in this field. The supports used in AMC will be discussed, including organic, inorganic, hybrid, carbohydrate, and cryogel monoliths. Schemes for attaching binding agents to these monoliths will be examined as well, such as covalent immobilization, biospecific adsorption, entrapment, molecular imprinting, and coordination methods. An overview will then be given of binding agents that have recently been used in AMC, along with their applications. These applications will include bioaffinity chromatography, immunoaffinity chromatography, immobilized metal-ion affinity chromatography, and dye-ligand or biomimetic affinity chromatography. The use of AMC in chiral separations and biointeraction studies will also be discussed.

Nanocomposite bilayers based on poly(vinyl alcohol) and chitosan functionalized with gallic acid

The development of active bilayer systems is a novel strategy for the application of active packaging to maintain or prolong the shelf-life of food products. A bilayer system was assembled in situ into a thermocompression unit through a two-step procedure. One of the layers was obtained by a casting process and consisted of a chitosan-based nanocomposite functionalized with gallic acid (GA); the other was shaped by the spreading of polyvinyl alcohol solution on the nanocomposite. Then, a stage of thermocompression formed the bilayer system. In this way, a feasible material with water vapor and oxygen barrier as well as UV barrier properties due to the presence of GA was designed by a thermocompression process which can be industrially scaled representing a technological progress. The formation of the bilayers was corroborated by SEM allowing discerning between both, the PVA layer and the nanocomposite layer. On the other hand, the corroboration of interactions between the layers of the system was carried out through ATR-FTIR and DSC analysis. The system was used as packaging of a food susceptible to undergo oxidation such as walnut flour, generating a delay in the formation of hydroperoxides and secondary oxidation compounds compared with a synthetic container. These results indicated that bilayer materials can be useful for the conservation of this type of foods.