Microparticles of Functionalized Polylactide Copolymers

1997 ◽  
Vol 501 ◽  
Author(s):  
K. E. Gonsalves ◽  
S. Jin ◽  
M-I Baraton
Keyword(s):  
Carboxylic Acid ◽  
Aspartic Acid ◽  
Room Temperature ◽  
Poly Vinyl Alcohol ◽  
Ionic Surfactant ◽  
Particle Sizes ◽  
Serine Residue ◽  
Aspartic Acid Residue ◽  
Carboxylic Acid Groups ◽  
Hydroxy Groups

ABSTRACTMicroparticles of poly(lactide) (PLac) and its copolymers with the amino acids, serine (P(Lac- Ser)), and aspartic acid (P(Lac-Asp)), respectively, were synthesized using the solvent evaporation microemulsion technique. Poly(vinyl alcohol) (PVA) was added as a non-ionic surfactant to stabilize the particles. The particle sizes are in the range of 200 nm. The surface of the particles was characterized by FTIR transmission spectroscopy under evacuation at room temperature and at 200°C. Hydroxy groups originating from PVA exist on the surfaces of the particles and they were observed at 3506 cm−1. Free hydroxy groups originating from the serine residue pendant to the copolymer P(Lac-Ser) backbone were observed at 3396 cm−1. Also, free carboxylic acid groups pendant to the copolymer P(Lac-Asp) backbone, originating from the aspartic acid residue, were observed at 3387 cm−1. The appearance of the free hydroxy or carboxylic acid groups in the IR spectra also showed that these hydrophilic functional groups moved to the surface of the particles in the process of microemulsion.

Electrolysis for the benign conversion of renewable feedstocks

2007 ◽  
Vol 79 (11) ◽  
pp. 2047-2057 ◽  
Author(s):  
Hans J. Schäfer ◽  
Michael Harenbrock ◽  
Elisabeth Klocke ◽  
Mark Plate ◽  
Andreas Weiper-Idelmann
Keyword(s):  
Fatty Acids ◽  
Electron Transfer ◽  
Carboxylic Acid ◽  
Functional Group ◽  
High Selectivity ◽  
Bond Forming ◽  
Carboxylic Acid Groups ◽  
Renewable Feedstocks ◽  
Good Accordance ◽  
Hydroxy Groups

A large variety of C,C-bond forming reactions and functional group interconversions can be achieved by electron transfer. For the conversion of renewable feedstocks, electrolysis has been applied to coupling of radicals generated by anodic decarboxylation of fatty acids and carboxylic acids of carbohydrates. Furthermore, a derivative of L-gulonic acid is converted nearly quantitatively into L-xylonolacton. Trimethyl aconitate from trimethyl citronate is dimerized stereoselectively at the cathode in 72 % yield to a cyclic hexamethyl ester by an inter- and intramolecular Michael addition. Two acetoxy groups are added anodically to methyl conjuenate (obtained from methyl linoleate) to form methyl (E)-9,12-diacetoxy-10-octenoate and methyl (E)-10,13-diacetoxy-11-octenoate in 85 % yield. The primary hydroxy groups in mono- and disaccharides can be oxidized to carboxylic acid groups in good yield and high selectivity by anodic oxidation with 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) as mediator. The results demonstrate that electrolysis is in good accordance with many of the 12 principles of green chemistry.

Preparation of cross-linked poly(vinyl alcohol) films from copolymers with benzoxaborole and carboxylic acid groups, and their degradability in an oxidizing environment

2020 ◽  
Vol 11 (14) ◽  
pp. 2469-2474
Author(s):  
Nao Hakuto ◽  
Katsuya Saito ◽  
Masayuki Kirihara ◽  
Yohei Kotsuchibashi
Keyword(s):  
Carboxylic Acid ◽  
Vinyl Alcohol ◽  
Carboxyl Groups ◽  
Poly Vinyl Alcohol ◽  
Carboxylic Acid Groups

Functionalized PVA films were prepared from copolymers with benzoxaborole and carboxyl groups.

Diffusion of molecular probes and the effects of their interactions with polymer matrices as studied by pulsed-field gradient NMR spectroscopy

2008 ◽  
Vol 86 (6) ◽  
pp. 579-585 ◽  
Author(s):  
Héloise Thérien-Aubin ◽  
Wilms E Baille ◽  
X X Zhu
Keyword(s):  
Nmr Spectroscopy ◽  
Carboxylic Acid ◽  
Field Gradient ◽  
Diffusion Coefficients ◽  
Molecular Probes ◽  
Poly Vinyl Alcohol ◽  
Pulsed Field Gradient Nmr ◽  
Pulsed Field ◽  
Self Diffusion ◽  
Carboxylic Acid Groups

Pulsed-field gradient NMR spectroscopy was used to study the interactions between small molecular probes and polymers bearing interacting groups. The self-diffusion coefficients of ethylene glycol and its oligomers and their methyl ester derivatives in poly(vinyl alcohol) gels were measured to study the effect of hydrogen bonding. The self-diffusion coefficients of small molecular probes containing hydroxyl, amine, and carboxylic acid groups were determined in several polymer matrices including poly(vinyl alcohol), poly(allylamine), and poly(acrylic acid) bearing lateral hydroxyl, amine, and carboxylic acid groups, respectively. The ionic interactions between the functional groups of the diffusants and of the polymers exhibited a marked effect on the diffusion of the molecular probes. For example, the reduced self-diffusion coefficients measured for a diffusant with a carboxylic acid group in a poly(allylamine) matrix were shown to be lower even though the molecular masses of the diffusants are similar.Key words: pulsed-field gradient NMR spectroscopy, self-diffusion, intermolecular interactions.

Kinetics of the Thermal Disappearance of Radicals Formed During the Radiolysis of Aspartic Acid

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Mihai Contineanu ◽  
iulia Contineanu ◽  
Ana Neacsu ◽  
Stefan Perisanu
Keyword(s):  
Thermal Resistance ◽  
Aspartic Acid ◽  
Room Temperature ◽  
Esr Spectra ◽  
Complex Mechanism ◽  
Radical Species ◽  
Mechanisms Of Formation ◽  
Kinetics Of

The radiolysis of the isomers L-, D- and DL- of the aspartic acid, in solid polycrystalline state, was investigated at room temperature. The analysis of their ESR spectra indicated the formation of at least two radicalic entities. The radical, identified as R3, resulting from the deamination of the acid, exhibits the highest concentration and thermal resistance. Possible mechanisms of formation of three radical species are suggested, based also on literature data. The kinetics of the disappearance of radical R3 indicated a complex mechanism. Three possible variants were suggested for this mechanism.

scholarly journals Grafting TRAIL through Either Amino or Carboxylic Groups onto Maghemite Nanoparticles: Influence on Pro-Apoptotic Efficiency

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 502
Author(s):  
Hanene Belkahla ◽  
Andrei Alexandru Constantinescu ◽  
Tijani Gharbi ◽  
Florent Barbault ◽  
Alexandre Chevillot-Biraud ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Cancer Therapy ◽  
Computational Study ◽  
Carcinoma Cells ◽  
Maghemite Nanoparticles ◽  
Carboxylic Acid Groups ◽  
Lung Carcinoma Cells ◽  
Biological Studies ◽  
Apoptotic Effect ◽  
Carboxylic Groups

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF cytokine superfamily. TRAIL is able to induce apoptosis through engagement of its death receptors DR4 and DR5 in a wide variety of tumor cells while sparing vital normal cells. This makes it a promising agent for cancer therapy. Here, we present two different ways of covalently grafting TRAIL onto maghemite nanoparticles (NPs): (a) by using carboxylic acid groups of the protein to graft it onto maghemite NPs previously functionalized with amino groups, and (b) by using the amino functions of the protein to graft it onto NPs functionalized with carboxylic acid groups. The two resulting nanovectors, NH-TRAIL@NPs-CO and CO-TRAIL@NPs-NH, were thoroughly characterized. Biological studies performed on human breast and lung carcinoma cells (MDA-MB-231 and H1703 cell lines) established these nanovectors are potential agents for cancer therapy. The pro-apoptotic effect is somewhat greater for CO-TRAIL@NPs-NH than NH-TRAIL@NPs-CO, as evidenced by viability studies and apoptosis analysis. A computational study indicated that regardless of whether TRAIL is attached to NPs through an acid or an amino group, DR4 recognition is not affected in either case.

scholarly journals Capsid assembly in a family of animal viruses primes an autoproteolytic maturation that depends on a single aspartic acid residue.

1994 ◽  
Vol 269 (18) ◽  
pp. 13680-13684
Author(s):  
A. Zlotnick ◽  
V.S. Reddy ◽  
R. Dasgupta ◽  
A. Schneemann ◽  
W.J. Ray ◽  
...  
Keyword(s):  
Aspartic Acid ◽  
Capsid Assembly ◽  
Aspartic Acid Residue

scholarly journals Conversion of secretory proteins into membrane proteins by fusing with a glycosylphosphatidylinositol anchor signal of alkaline phosphatase

1994 ◽  
Vol 301 (2) ◽  
pp. 577-583 ◽  
Author(s):  
K Oda ◽  
J Cheng ◽  
T Saku ◽  
N Takami ◽  
M Sohda ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Endoplasmic Reticulum ◽  
Aspartic Acid ◽  
Chimeric Protein ◽  
Attachment Site ◽  
In Vitro Translation ◽  
Placental Alkaline Phosphatase ◽  
Wild Type ◽  
Aspartic Acid Residue

Placental alkaline phosphatase (PLAP) is initially synthesized as a precursor (proPLAP) with a C-terminal extension. We constructed a recombinant cDNA which encodes a chimeric protein (alpha GL-PLAP) comprising rat alpha 2u-globulin (alpha GL) and the C-terminal extension of PLAP. Two molecular species (25 kDa and 22 kDa) were expressed in the COS-1 cell transfected with the cDNA for alpha GL-PLAP. Only the 22 kDa form was labelled with both [3H]stearic acid and [3H]ethanolamine. Upon digestion with phosphatidylinositol-specific phospholipase C the 22 kDa form was released into the medium, indicating that this form is anchored on the cell surface via glycosylphosphatidylinositol (GPI). A specific IgG raised against a C-terminal nonapeptide of proPLAP precipitated the 25 kDa form but not the 22 kDa form, suggesting that the 25 kDa form is a precursor retaining the C-terminal propeptide. When a mutant alpha GL-PLAP, in which the aspartic acid residue is replaced with tryptophan at a putative cleavage/attachment site, was expressed in COS-1 cells, the 25 kDa precursor was the only form found inside the cell and retained in the endoplasmic reticulum, as judged by immunofluorescence microscopy. In vitro translation programmed with mRNAs coding for the wild-type and mutant forms of alpha GL-PLAP demonstrated that the C-terminal propeptide was cleaved from the wild-type chimeric protein, but not from the mutant one. This gave rise to the 22 kDa form attached with a GPI anchor, suggesting that GPI is covalently linked to the aspartic acid residue (Asp159) of alpha GL-PLAP. Taken together, these results indicate that the C-terminal propeptide of PLAP functions as a signal to render alpha GL a GPI-linked membrane protein in vitro and in vivo in cultured cells, and that the chimeric protein constructed in this study may be useful for elucidating the mechanism underlying the cleavage of the propeptide and attachment of GPI, which occur in the endoplasmic reticulum.

Dual-temperature and pH responsive (ethylene glycol)-based nanogels via structural design

2014 ◽  
Vol 5 (8) ◽  
pp. 3061-3070 ◽  
Author(s):  
Yohei Kotsuchibashi ◽  
Ravin Narain
Keyword(s):  
Carboxylic Acid ◽  
Ethylene Glycol ◽  
Salt Concentration ◽  
Structural Design ◽  
Solution Temperature ◽  
Ph Responsive ◽  
Solution Ph ◽  
Critical Solution Temperature ◽  
Carboxylic Acid Groups ◽  
The Core

Dual-temperature and pH responsive (ethylene glycol)-based nanogels were synthesized. Both the core and the shell of the nanogels showed a lower critical solution temperature (LCST) and the LCST of the shell was strongly affected by the solution pH and salt concentration due to the presence of carboxylic acid groups at the nanogel surface.

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