Tailor-Made Poly(vinylamine) via Purple LED-Activated RAFT Polymerization of N-vinylformamide.

Photo-iniferter reversible addition-fragmentation chain transfer (PI-RAFT) polymerization of N-vinylformamide (NVF) is demonstrated by using purple light. PNVFs with predetermined molar masses and narrow molar mass distributions are obtained. High RAFT chain-end fidelity is confirmed by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) and electrospray-ionization time-of-flight mass spectrometry (ESI-TOF-MS), and chain extension experiment. To demonstrate the potential of this approach, an original poly(N-vinylpyrrolidone)-b-poly(N-vinylformamide) (PVP-b-PNVF) diblock copolymer is synthesized and characterized by aqueous size-exclusion chromatography (SEC), asymmetric flow field-flow fractionation (A4F), and 1 H diffusion-ordered spectroscopy nuclear magnetic resonance (1 H DOSY NMR). Finally, selective hydrolysis of PNVF block to corresponding pH-responsive poly(N-vinylpyrrolidone)-b-poly(N-vinylformamide) (PVP-b-PVAm) is performed.

G-quadruplex aptamer selection using capillary electrophoresis-LED-induced fluorescence and Illumina sequencing.

One of the major difficulties that arises when selecting aptamers containing a G-quadruplex is the correct amplification of the ssDNA sequence. Can aptamers containing a G-quadruplex be selected from a degenerate library using non-equilibrium capillary electrophoresis (CE) of equilibrium mixtures (NECEEM) along with high-throughput Illumina sequencing? In this article, we present some mismatches of the G-quadruplex T29 aptamer specific to thrombin, which was PCR amplified and sequenced by Illumina sequencing. Then, we show the proportionality between the number of sequenced molecules of T29 added to the library and the number of sequences obtained in Illumina sequencing, and we find that T29 sequences from this aptamer can be detected in a random library of ssDNA after the sample is fractionated by NECEEM, amplified by PCR, and sequenced. Treatment of the data by the counting of double-stranded DNA T29 sequences containing a maximum of two mismatches reveals a good correlation with the enrichment factor (fE). This factor is the ratio of the number of aptamer sequences found in the collected complex sample divided by the total number of sequencing reads (aptamer and non-aptamer) plus the quantity of T29 molecules (spiked into a DNA library) injected into CE.

Recent advances in amino acid analysis by capillary electromigration methods: June 2015-May 2017.

In the tenth edition of this article focused on recent advances in amino acid analysis using capillary electrophoresis, we describe the most important research articles published on this topic during the period from June 2015 to May 2017. This article follows the format of the previous articles published in Electrophoresis. The new developments in amino acid analysis with CE mainly describe improvements in CE associated with mass spectrometry. Focusing on applications, we mostly describe clinical works, although metabolomics studies are also very important. Finally, works focusing on amino acids in food and agricultural applications are also described.

ssDNA degradation along capillary electrophoresis process using a Tris buffer.

Tris-Acetate buffer is currently used in the selection and the characterization of ssDNA by capillary electrophoresis (CE). By applying high voltage, the migration of ionic species into the capillary generates a current that induces water electrolysis. This phenomenon is followed by the modification of the pH and the production of Tris derivatives. By injecting ten times by capillary electrophoresis ssDNA (50 nM), the whole oligonucleotide was degraded. In this paper, we will show that the Tris buffer in the running vials is modified along the electrophoretic process by electrochemical reactions. We also observed that the composition of the metal ions changes in the running buffer vials. This phenomenon, never described in CE, is important for fluorescent ssDNA analysis using Tris buffer. The oligonucleotides are degraded by electrochemically synthesized species (present in the running Tris vials) until it disappears, even if the separation buffer in the capillary is clean. To address these issues, we propose to use a sodium phosphate buffer that we demonstrate to be electrochemically inactive.