Conjugation of Polymers with Biomolecules and Polymeric Vaccine Development Technologies
Mesut Karahan in Synthetic Peptide Vaccine Models, 2021
If a polymer is formed by repeating a single monomer unit, it is called a homopolymer (Figure 5.3).Chemical bonding of Lactideo and Glicolideo formation to PLGA. (Image by “Anamaria Teodora Coêlho Rios da Silva.” The image is licensed under a CC0. This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication, https://commons.wikimedia.org/wiki/File:S%C3%ADntese_PLGA.jpg.)
Next-Generation Sequencing (NGS) for Companion Diagnostics (CDx) and Precision Medicine
Il-Jin Kim in Companion Diagnostics (CDx) in Precision Medicine, 2019
Weakness: The Ion Torrent system is well known for inaccurate indel calls in homopolymer regions. Although Illumina reportedly has the same issue, it is much worse in the Ion Torrent system.7, 18, 24 When the same dNTPs are incorporated and recorded, pH change signals are not perfectly linear with the number of nucleotides, causing inaccurate base calling and high error rates. There are reports that a homopolymer with more than seven bases is hard to sequence correctly with Ion Torrent or pyrosequencing technologies.24,31 However, in our own experience with Ion Torrent system, even 2–3 bp repeats of the same nucleotides (i.e., AA, CC, or TTT) are very challenging to call correctly, leading to false-positive variants. Notwithstanding several advantages (low equipment cost, low input DNA, faster sequencing time, and flexibility for sequencing chips) over other NGS systems, very high error rates caused by the homopolymer issue, especially for deletions and insertions, is the biggest hurdle for this system to be a leading one for clinical sequencing and CDx application. If the Ion Torrent system is used, it is ideal to check all identified insertion or deletion mutations by using the raw sequencing read view (i.e., Integrative Genomics Viewer) and confirm any suspicious variant or mutation by another sequencing method like Sanger sequencing.
Synthetic Polymers in Cosmetics
E. Desmond Goddard, James V. Gruber in Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
If a single monomer is used to create a polymer, the resulting chain is known as a homopolymer. Homopolymers can be straight-chained or branched (Fig. 1) (3). Polymer characteristics are greatly affected by the architecture of the chains. If one imagines that a linear homopolymer is like a wooden two-by-four, and a branched polymer is like a pine tree, one can further imagine that a certain mass of two-by-fours occupies much less space than a similar mass of pine trees. Branching polymers occupy greater molecular space than their linear cousins. Likewise, the linear polymers, like the linear two-by-fours, are able to pack much more closely. This creates regions of high crystallinity (i.e., high order), which provide the polymers with increased strength and higher melting temperatures.
Cytogenetic and molecular genetic methods for chromosomal translocations detection with reference to the KMT2A/MLL gene
Published in Critical Reviews in Clinical Laboratory Sciences, 2021
Nikolai Lomov, Elena Zerkalenkova, Svetlana Lebedeva, Vladimir Viushkov, Mikhail A. Rubtsov
Both methods are referred to as short-read sequencing since they give reads up to 400 nucleotides, for Ion Torrent, and up to 300 nucleotides, for Illumina. The short lengths of the reads are compensated for by paired-end sequencing technology, in which a rather long fragment (up to 1 kb) is sequenced first from one end and then from the other. The main advantage of Illumina is the high-throughput—the ability to simultaneously sequence a large number of fragments, resulting in greater sequencing depth and a lower cost per base pair. The main advantage of Ion Torrent is the short runtime because it does not require the optical detection of four different lasers at each step; instead, the addition of A, C, G, and T nucleotides is directly translated into digital information (0, 1) on a semiconductor chip. The Ion Torrent instrument also offers the possibility of automated sample preparation, making this method the least labor-intensive. The whole process required for sample preparation and the sequencing of the human genome takes approximately one day using the Ion Torrent, compared with 2–3 days for Illumina. The main disadvantage is the high error rate on homopolymer repeats longer than 6 bp because the correlation between the number of bases incorporated and the subsequent voltage change is not perfect [89].
Responsive polymer conjugates for drug delivery applications: recent advances in bioconjugation methodologies
Published in Journal of Drug Targeting, 2019
Daniel Cristian Ferreira Soares, Caroline Mari Ramos Oda, Liziane Oliveira Fonseca Monteiro, Andre Luis Branco de Barros, Marli Luiza Tebaldi
Modern techniques of living radical polymerisation (LRP) are used to conjugation of proteins with synthetic polymers covalently since it reduces termination reactions and permits a high level of control over molar mass and its distribution. Furthermore, the polymer chain may be extended with the addition of monomers due to the chain-end functionality. Thus, it is possible to produce systems with well-defined molar mass and desired polymeric architectures, which are impossible to achieve by conventional radical polymerisation. Well-defined molecular architectures are crucial to achieving homogeneity of the structure, and consequently to improve the effect on the activity of the conjugate. Among the LRP techniques, atom-transfer radical polymerisation (ATRP) and reversible addition-fragmentation chain transfer (RAFT) polymerisation are considered the most effective in producing well-defined polymer–protein conjugates [17–21].
Bacterial anti-adhesion activity based on the electrochemical properties of polymethacrylates bearing ferrocenyl pendant groups
Published in Biofouling, 2018
Ronald W. Nguema Edzang, The Hy Duong, Jean-François Briand, Marlène Lejars, Jean-Manuel Raimundo, Christine Bressy, Hugues Brisset
Each homopolymer was dissolved in toluene at 2.5 or 21 wt%. Two µl of this solution were deposited on the working electrode of 16 wells (two columns of eight wells each) which corresponded to 50 or 420 µg of polymer, respectively. The thickness of the polymer films was estimated at a maximum of 7.4 µm and 62.5 µm respectively, considering a diameter of the working electrode of 2.5 mm and a density of the polymer around 1.37 (Chernyy et al. 2017). The microplate was dried for four days at room temperature. The as-prepared films were composed of randomly organized homopolymer chains. ASW was introduced in order to record cyclic voltammograms (CV) between 0.25 and 0.70 V vs AgCl at 25 mV s−1. CV analysis in ASW allowed the removal of any toluene traces, which could be toxic for the bacterial cells. The ASW was removed and the plate was dried for two days before sterilization under UV for 30 min. This protocol was repeated for each polymer evaluated in this work.