Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0267964 (PAA)
 2,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Controlled drug delivery and gene transfection involve contact of artificial polyelectrolytic systems that can interact dramatically with biopolymers and cells when they are introduced in blood. Given the complexity of body aqueous media in terms of physical chemistry, a model approach was selected in attempt to understand the behavior of artificial polyelectrolytes introduced in body fluids. Selection in terms of molecular weight was highlighted in a previous paper. In the present study the formation and the stability of fractions obtained when a polycation is added to a polyanion according to a titrating process mimicking injection into blood was considered for different polycation/polyanion couples. Poly(amino serinate) and poly(L-lysine) were used as polybases, and poly(acrylic acid), poly(L-lysine citramide) and poly(L-lysine citramide imide) as polyacids. Four fractions corresponding to different positive/negative charge ratios were formed for each couple. At low polyion concentration (13 mg/L) and given salt concentration, the stability of the complex fractions depended on molecular weight and charge density of the polyions. The NaCl concentration required to destabilize the different interpolyelectrolyte complexes was found to decrease from the first fraction to the fourth one. Upon decreasing the salt concentration, macroscopic flocculation occurred in the case of PLL/PAA complex fractions only. For the other couples, dynamic light scattering showed that several hundreds nanometer sized particles were formed that were stable in a broad range of NaCl concentration, including the physiological 0.15 ionic strength. At higher polyion concentrations, stable solid precipitate was formed regardless of the system. The absence of flocculation in the case of highly diluted poly(L-lysine citramide) and poly(L-lysine citramide imide) polyanions in salted media is assigned to the presence of non-ionic hydroxyl and amide polar groups along the complexed chains. Data show that introducing non-ionic functions along the polyelectrolyte chains is a good means to keep interpolyelectrolyte complexes dispersed in salted media, a conclusion of interest in the field of condensation of genes by polycations.
 ...
PMID:Polyelectrolyte complex formation and stability when mixing polyanions and polycations in salted media: a model study related to the case of body fluids. 1591 Dec 24

Poly(methyl acrylate)-grafted poly(methyl-n-propylsilane) (PMPrS-g-PMA) and poly(acrylic acid)-grafted PMPrS (PMPrS-g-PAA) were synthesized by gamma-ray-induced graft polymerization, and the association behavior of these graft copolymers was investigated in selective solvents composed of good and poor solvents for the PMPrS main chain. Fluorescence spectroscopy with perylene as a fluorescent probe revealed that PMPrS-g-PAA in a water/THF mixed solvent self-assembles into micelles with a swollen core of PMPrS chains in the water content range of 50-95%. UV spectroscopy demonstrated that a further increase of the water content gives rise to the conformational transition of the PMPrS chains in the micelle core from the random conformation to the conformation that corresponds to that in the solid state at a water content of ca. 95%, independent of the grafting yield. Similar behavior was also observed in DMSO/THF solutions of PMPrS-g-PMA, for which the conformational transition occurred at the constant DMSO content of ca. 95%. These results indicate that solvatochromic behavior of polysilane, which is a characteristic feature of polysilane, proved to provide information on the inner structure of those micelles: PMPrS chains in the core undergo conformational transition as the content of the poor solvents for PMPrS increases, while maintaining the micelle structure.
 ...
PMID:Conformational transition of the core chain in radiation-modified polysilane micelles formed in selective solvents. 1608 71

We developed novel acrylic-based polymers that can be used as mucoadhesive delivery systems. Poly(acrylic acid) hydrogels were modified by grafting adhesion promoter chains such as poly(ethylene glycol) (PEG) onto their back-bone chains, thus promoting the adhesive process by interpenetration. The copolymers synthesized were designated as P(AA-g-EG). Hydrogels were synthesized using PEG of two different molecular weights, 1000 and 2000, and with varying molar feed ratio of AA-EG (20:80, 40:60, 60:40, 80:20, 12:88, 25:75, 44:56, 67:33). The copolymers were synthesized by using free radical solution UV-polymerization. The effects of different PEG-tethered structures on mucoadhesion were studied using a tensiometric testing and the work of adhesion was calculated. Preswollen P(AA-g-EG) copolymer films composed of 40% acrylic acid (AA) and 60% ethylene glycol (EG), containing PEG 1000 tethers, exhibited the highest value for the work of mucoadhesion, 130 x 10(-3)+/-27 x 10(-3) mJ, that is five times higher than the formulation composed of pure PAA. Based on these results and associated molecular analysis, we conclude that the higher mucoadhesive properties of this specific copolymer were the result of the synergistic effects of both monomers. AA functional groups allowed the polymer to form multiple hydrogen bonds with the glycoproteins present in the mucus. PEG tethers possibly acted as mucoadhesive promoters, enhancing interpenetration of polymer chains into the mucus.
 ...
PMID:Design of poly(ethylene glycol)-tethered copolymers as novel mucoadhesive drug delivery systems. 1636 28

Polyelectrolyte multilayer thin films were prepared by an alternate deposition of poly(allylamine hydrochloride) (PAH) and anionic polysaccharides {carboxymethylcellulose (CMC) and alginic acid (AGA)} on the surface of a gold (Au) disk electrode, and the binding of ferricyanide [Fe(CN)(6)](3)(-) and hexaammine ruthenium ions [Ru(NH(3))(6)](3+) to the films was evaluated. Poly(acrylic acid) (PAA) was also employed as a reference polyanion bearing carboxylate side chains. A quartz-crystal microbalance study showed that PAH-CMC and PAH-AGA multilayer films grow exponentially as the number of depositions increases. The thicknesses of five bilayers of (PAH-CMC)(5) and (PAH-AGA)(5) films were estimated to be 150 +/- 20 and 90 +/- 15 nm, respectively, in the dry state. The PAH/polysaccharide multilayer film-coated Au electrodes exhibited a redox response to the [Fe(CN)(6)](3)(-) ion dissolved in solution, irrespective of the sign of the surface charge of the film, suggesting the high permeability of the films to the [Fe(CN)(6)](3)(-) ion. In contrast, the PAH-PAA film-coated Au electrodes exhibited a redox response only when the outermost surface of the film was covered with a positively charged PAH layer. However, the permeation of the [Ru(NH(3))(6)](3+) cation was severely suppressed for all of the multilayer films. It was possible to confine the [Fe(CN)(6)](3)(-) ion in the films by immersing the film-coated electrodes in a 1 mM [Fe(CN)(6)](3)(-) solution for 15 min. Thus, the [Fe(CN)(6)](3)(-)-confined electrodes exhibited a cyclic voltammetric response in the [Fe(CN)(6)](3)(-) ion-free buffer solution. The loading of the [Fe(CN)(6)](3)(-) ion in the films was higher when the surface charge of the film was positive and increased with increasing film thickness. It was also found that the [Fe(CN)(6)](3)(-) ion confined in the films serves as an electrocatalyst that oxidizes ascorbic acid in solution.
 ...
PMID:Redox properties of the ferricyanide ion on electrodes coated with layer-by-layer thin films composed of polysaccharide and poly(allylamine). 1651 97

Poly(lactic-co-glycolic acid) (PLGA) nanospheres containing protease inhibitors, camostat mesilate (CM) and nafamostat mesilate (NM), were prepared by the emulsion solvent diffusion methods in water or in oil, and the w/o/w emulsion solvent evaporation method. The average diameter of PLGA nanospheres prepared in the water system were about 150-300 nm, whereas those prepared in the oil system were 500-600 nm. Among the three methods, these drugs were the most efficiently encapsulated up to 60-70% in PLGA nanospheres in the oil system. Other factors that may influence drug encapsulation efficiency and in vitro release such as drug load, molecular weight of polymer were also investigated. Both the CM- and NM-loaded nanospheres prepared in the water system immediately released about 85% of the drug upon dispersed in the release medium while the drug initial burst of nanospheres prepared by the emulsion solvent diffusion in oil method reduced to 30% and 60% for CM and NM, respectively. Poly(aspartic acid) (PAA), a complexing agent for cationic water soluble drugs, showed little effect on the encapsulation efficiency and release behavior for CM and NM. The DSC study and AFM pictures of nanospheres demonstrated that temperature-dependent drug release behavior was ascribable to the glass transition temperature of the polymer, which also affected the morphology of nanospheres upon dispersed in the release medium and influenced the drug release consequently.
 ...
PMID:Properties of poly(lactic-co-glycolic acid) nanospheres containing protease inhibitors: camostat mesilate and nafamostat mesilate. 1655 94

Patterned surface modification of poly(dimethylsiloxane) (PDMS) is achieved by combining ultraviolet-initiated graft polymerization (UV-GP) and photolithography. Poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA) patterns were grafted onto PDMS with micrometer-scale feature edge resolution. The morphology and chemical composition of the grafted layers were assessed by optical and atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and XPS imaging. AFM section analyses demonstrated the deposition of 33 +/- 1 and 62 +/- 8 nm thick patterned films of PAA and PMAA, respectively. Spatially resolved C 1s XPS provided images of carboxylic acid functionalities, verifying the patterned deposition of acrylate films on PDMS. These observations demonstrate the general usefulness of UV-GP and photolithography for micropatterning.
 ...
PMID:Photolithographically patterned surface modification of poly(dimethylsiloxane) via UV-initiated graft polymerization of acrylates. 1658 8

Poly(acrylic acid) is shown to control the level of SWNT dispersion in aqueous mixtures and the state of dispersion in a solid composite. At low pH, PAA-stabilized suspensions containing 0.1 wt % SWNT have a waterlike viscosity, but this mixture thickens as the pH is raised. This behavior is reversed when pH is again lowered. Changing pH varies the SWNT microstructure between aggregated and well-exfoliated states, as evidenced by electron microscopy and electrical conductivity measurements.
 ...
PMID:Tunable single-walled carbon nanotube microstructure in the liquid and solid states using poly(acrylic acid). 1668 24

Poly(ethylene terephthalate) (PET) films were treated by argon plasma following by graft copolymerization with acrylic acid (AAc). The obtained PET-surface grafted PAA (PET-g-PAA) was coupled with chitosan (CS) and o-carboxymethylchitosan (OCMCS) molecules, respectively. Their surface physicochemical properties were characterized by X-ray photoelectron spectroscopy (XPS), water contact angle and streaming potential measurements. The PET-g-PAA surface containing carboxylic acid, CS immobilized PET surface containing amino and OCMCS immobilized PET surface containing both carboxylic acid and amino groups, make the PET surface exhibited a hydrophilic character. The blood compatibility was evaluated by platelet contacting experiments and protein adsorption experiments in vitro. The results demonstrate that the PET surface coupling OCMCS shows much less platelet adhesive and fibrinogen adsorption compared to the other surface modified PET films. The anticoagulation of PET-OCMCS is ascribed to the suitable balance of hydrophobicity/hydrophilicity, surface zeta potential and the low adsorption of protein.
 ...
PMID:Blood compatibility of surface-engineered poly(ethylene terephthalate) via o-carboxymethylchitosan. 1678 39

Poly(acrylic acid) (PAA)-grafted cellulose copolymer beads were synthesized and tested in vitro as an adsorbent for selective removal of low-density lipoprotein (LDL) from human plasma. The copolymers were prepared by graft copolymerization of acrylic acid (AA) onto porous cellulose beads using cerium ammonium nitrate (CAN) as an initiator. The effect of initiator concentration, monomer amount and reaction time on the grafting was examined, and it revealed that the extent of grafting could be controlled by setting the appropriate reaction conditions. In vitro batch-wise adsorption tests were conducted to evaluate the lipoprotein sorption properties of the resulted copolymer beads, and the effect of grafting conditions on the adsorption performance was investigated. It was shown that the binding capacities of the best adsorbent derived from the appropriate reaction conditions could reach 4.96 mg/g total cholesterol (TC) and 4.46 mg/g LDL cholesterol (LDL-C) from human plasma, respectively, without significantly affecting the contents of beneficial constitutes such as high-density lipoprotein (HDL) and total proteins (TP). The influences of plasma amount and adsorption period on the adsorption properties were also determined and analyzed. It appears that this kind of copolymer is worthy of being developed as an alternative LDL adsorbent.
 ...
PMID:Synthesis and in vitro sorption properties of PAA-grafted cellulose beads for selective binding of LDL. 1689 13

Poly(amino acid)s (PAAs) were evaluated as coating polymers for long-circulating liposomes. The pharmacokinetics of PAA-coated liposomes were assessed in rats. Prolonged circulation times were obtained, comparable to those reported for poly(ethylene glycol) (PEG)-liposomes. Besides, the enzymatic degradability of PAAs was studied. PAAs - in free as well as liposome-associated form - are degradable by proteases, which is beneficial for reducing the risks of accumulation in vivo. Furthermore, complement activation by PAA-liposomes was evaluated in vitro and in vivo. Like other liposome types, they appear to activate the complement system. However, a role of endotoxin contamination of the PAA-liposome formulations used cannot be excluded in our complement activation studies.
 ...
PMID:Poly(amino acid)s: promising enzymatically degradable stealth coatings for liposomes. 1714 45


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>