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Biomedical subjects

Milos Barut

Publications and source records attributed to Milos Barut.

8 recordsLinked to original sources

Determination of DNA entrapment into liposomes using short monolithic columns.

A high-performance liquid chromatography (HPLC) method for the determination of DNA entrapment efficiency in liposomes has been developed. Plasmid DNA was encapsulated into positively charged liposomes. Non-entrapped DNA was separated by ultracentrifugation from liposomes and supernatant was chromatographed on Convective Interaction Media (CIM) DEAE disk. The elution of DNA was monitored by the absorbance at 260 nm and the quantity of DNA in the tested sample was calculated from the integrated peak areas using the appropriate standard curve. This method is fast, simple, precise and does not require any kind of DNA labelling in contrast with mostly used methods for determination of DNA entrapment efficiency.

Chromatography, High Pressure Liquid↗

Anion-exchange chromatography using short monolithic columns as a complementary technique for human serum albumin depletion prior to human plasma proteome analysis.

In order to enable the detection of low abundance proteins from human plasma, it is necessary to remove high abundance proteins. Among them, human serum albumin and immunoglobulin G represent more than 75% of all such proteins. In this paper, the characterization of short monolithic columns was performed followed by the optimization of a multidimensional approach, known as conjoint liquid chromatography, to deplete human serum albumin and immunoglobulin G from a human plasma sample. Two different chromatographic modes were used: ion-exchange chromatography and affinity chromatography. A monolithic stationary phase (convective interaction media disk) bearing strong anion-exchange groups and another immobilized with protein G were placed in series into one housing. The optimal binding conditions were found that removed a majority of human serum albumin and immunoglobulin G from the human plasma sample. This method was compared to the depletion using a combination of pseudo-affinity and affinity columns. The results of the human serum albumin and immunoglobulin G depletion were confirmed by 2D electrophoresis. It has been shown that anion-exchange and affinity chromatography using convective interaction media monolithic columns can represent an efficient complementary technique for human serum albumin and immunoglobulin G removal from human plasma.

Biomarkers↗

Purification of genomic DNA by short monolithic columns.

The isolation and purification of nucleic acids is essential for many procedures in molecular biology. After showing that bacterial and eukaryotic genomic DNA can be specifically bound to the CIM DEAE monolithic column, this characteristic was exploited in development of a simple and fast chromatographic procedure for isolation and purification of genomic DNA from cell lysates that does not include the usage of toxic organic solutions. The purity and the quality of the isolate as well as the duration of the procedure was similar to other chromatographic methods used today for isolation of genomic DNA, but the initial sample volume was not restricted.

Chromatography, Ion Exchange↗

Chromatographic detection of residual cellular DNA on short monolithic columns.

Analysis of crude samples from biotechnological processes is often required to demonstrate that residual host cell impurities are reduced or eliminated during purification. Current knowledge suggests that a continuous-cell-line DNA can be considered a cellular contaminant rather than a significant risk factor requiring removal to extremely low levels. Anion-exchange chromatography is one of the most important methods used in the downstream processing and analysis of different biomolecules. In this article, an application using Convective Interaction Media monolithic columns to improve the detection of residual cellular DNA is described.

Cell Line↗

Convective interaction media short monolithic columns: enabling chromatographic supports for the separation and purification of large biomolecules.

New therapeutics that are being developed rely more and more on large and complex biomacromolecules like proteins, DNA, and viral particles. Manufacturing processes are being redesigned and optimized both upstream and downstream to cope with the ever-increasing demand for the above target molecules. In downstream processing, LC still represents the most powerful technique for achieving high yield and high purities of these molecules. In most cases, however, the separation technology relies on conventional particle-based technology, which has been optimized for the purification of smaller molecules. New technologies are, therefore, needed in order to push the downstream processing ahead and into the direction that will provide robust, productive, and easy to implement methods for the production of novel therapeutics. New technologies include the renaissance of membranes, various improvements of existing technologies, but also the introduction of a novel concept--the continuous bed or monolithic stationary phases. Among different introduced products, Convective Interaction Media short monolithic columns (SMC) that are based on methacrylate monoliths exhibit some interesting features that make them attractive for these tasks. SMC can be initially used for fast method development on the laboratory scale and subsequently efficiently transferred to preparative and even more importantly to industrial scale. A brief historical overview of methacrylate monoliths is presented, followed by a short presentation of theoretical considerations that had led to the development of SMC. The design of these columns, as well as their scale-up to large units, together with the methods for transferring gradient separations from one scale to another are addressed. Noninvasive methods that have been developed for the physical characterization of various batches of SMC, which fulfill the regulatory requirements for cGMP production, are discussed. The applications of SMC for the separation and purification of large biomolecules, which demonstrate the full potential of this novel technology for an efficient downstream processing of biomolecules, are also presented.

Biopolymers↗

Application of short monolithic columns for fast purification of plasmid DNA.

Anion-exchange chromatography is one of the most important methods in downstream processing of plasmid DNA, both as a process and as an analytical technique. Separation of plasmid DNA on traditional particle-based anion-exchange supports is usually slow. Moreover, such supports have a low capacity for plasmid DNA due to the steric exclusion effects. In this work, the separation of plasmid DNA using short monolithic columns, Convective Interaction Media, will be presented. It will be demonstrated that plasmid DNA can be purified from bacterial cells using alkaline lysis followed by chromatography on a very short weak anion-exchange chromatographic columns-disks-with good purity and quality within a short time. Furthermore, the separation of plasmid DNA from cell RNA can be carried out without the need of adding RNAse. Fast and efficient method for in-process control of the purified plasmid will be described as well.

Anions↗

Application of short monolithic columns for improved detection of viruses.

Monolithic chromatography media represent a novel generation of stationary phases introduced in the last 10-15 years providing a chromatography matrix with enhanced mass transfer and hydrodynamic properties. These features allow for an efficient and fast separation of especially large biomolecules like e.g., DNA and viruses. In this study, the enrichment of virus RNA on short monolithic columns prior to molecular detection of viruses is described. Measles and mumps viruses were chosen as model viruses. The results show that it is possible to bind viral RNA on monoliths and concentrate viral nucleic acids from a fairly dilute sample. Consequently, a potential application of short monolithic columns is the concentration of virus RNA to improve the sensitivity and selectivity of viral detection with the possibility of isolating viral RNA from cell-free biological fluids.

Chromatography, DEAE-Cellulose↗

Short monolithic columns as stationary phases for biochromatography.

Monolithic supports represent a novel type of stationary phases for liquid and gas chromatography, for capillary electrochromatography, and as supports for bioconversion and solid phase synthesis. As opposed to individual particles packed into chromatographic columns, monolithic supports are cast as continuous homogeneous phases. They represent an approach that provides high rates of mass transfer at lower pressure drops as well as high efficiencies even at elevated flow rates. Therefore, much faster separations are possible and the productivity of chromatographic processes can be increased by at least one order of magnitude as compared to traditional chromatographic columns packed with porous particles. Besides the speed, the nature of the pores allows easy access even in the case of large molecules, which make monolithic supports a method of choice for the separation of nanoparticles like pDNA and viruses. Finally, for the optimal purification of larger biomolecules, the chromatographic column needs to be short. This enhances the speed of the separation process and reduces backpressure, unspecific binding, product degradation and minor changes in the structure of the biomolecule, without sacrificing resolution. Short Monolithic Columns (SMC) were engineered to combine both features and have the potential of becoming the method of choice for the purification of larger biomolecules and nanopartides on the semi-preparative scale.

Biomedical Engineering↗