Home About us Contact
|
Home About us Contact | ||
|
|
||
pH-responsive Polymer (ph-responsive + polymer)
Selected AbstractsSynthetic pH-Responsive Polymers for Protein TransductionADVANCED MATERIALS, Issue 38-39 2009William B. Liechty A pH-responsive, endosomal membrane disruptive, metabolite-derived polyamide PP-75 is developed to deliver the MBP-Apoptin fusion protein, which induces tumor-specific apoptosis into human osteogenic sarcoma Saos-2 cells. The intracellular distribution and colocalization of MBP-Apoptin-AF647 (MA-AF649) and PP-75-FITC provide strong evidence that PP-75 both enhances uptake and facilitates cytoplasmic release of MBP-Apoptin. [source] Conformational effects on the performance and selectivity of a polymeric pseudostationary phase in electrokinetic chromatographyELECTROPHORESIS, Issue 4-5 2005Jonathan P. McCarney Abstract The effect of the conformation of a polymeric pseudostationary phase on performance and selectivity in electrokinetic chromatography was studied using an amphiphilic pH-responsive polymer that forms compact intramolecular aggregates (unimer micelles) at low pH and a more open conformation at high pH. The change in conformation was found to affect the electrophoretic mobility, retention, selectivity, and separation efficiency. The low-pH conformer has higher electrophoretic mobility and greater affinity for most solutes. The unimer micelle conformation was also found to provide a solvation environment more like that of micelles and other amphiphilic self-associative polymers studied previously. It was not possible to fully characterize the effect of conformation on efficiency, but very hydrophobic solutes with long alkyl chains appeared to migrate with better efficiency when the unimer micelle conformation was employed. The results imply that polymers with a carefully optimized lipophilic-hydrophilic balance that allow self-association will perform better as pseudostationary phases. In addition, the results show that electrokinetic chromatography is a useful method for determining the changes in solvation environment provided by stimuli-responsive polymers with changes in the conditions. [source] Synthesis and solution properties of a new pH-responsive polymer containing amino propanesulfonic acid residuesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2003Sk. Asrof Ali Abstract The reaction of diallyl amine with 1,3-propane sultone led to the synthesis of the zwitterionic monomer 3-(N,N -diallylammonio)propanesulfonate. The sulfobetaine was cyclopolymerized in water in the presence of sodium chloride with t -butylhydroperoxide as an initiator to afford a polysulfobetaine (PSB) in very good yield. PSB, upon treatment with sodium hydroxide, was converted into an anionic polyelectrolyte (APE). Although APE was readily soluble in salt-free water, PSB needed the presence of low-molecular-weight salts (e.g., NaCl, KI, etc., in the range of 0.135,1.04 N) for its dissolution. The solution properties of PSB and APE were investigated with potentiometric and viscometric techniques. The basicity constant of the amine was apparent and followed the modified Henderson,Hasselbalch equation; as the degree of protonation (,) of the whole macromolecule increases, the protonation of the amine nitrogens becomes increasingly more difficult. The composition and phase diagram of the aqueous two-phase systems of APE/PSB and poly(ethylene glycol) were also explored. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 172,184, 2003 [source] Mechanism of pH-sensitive polymer-assisted protein refolding and its application in TGF-,1 and KGF-2BIOTECHNOLOGY PROGRESS, Issue 5 2009Zhifeng Huang Abstract Refolding of proteins at high concentrations often results in non-productive aggregation. This study, through a unique combination of spectroscopic and chromatographic analyzes, provides biomolecular evidence to demonstrate the ability of Eudragit S-100, a pH-responsive polymer, to enhance refolding of denatured-reduced lysozyme at high concentrations. The addition of Eudragit in the refolding buffer significantly increases lysozyme refolding yield to 75%, when dilution refolding was conducted at 1 mg/mL lysozyme. This study shows evidence of an electrostatic interaction between oppositely charged lysozyme and the Eudragit polymer during refolding. This ionic complexing of Eudragit and lysozyme appears to shield exposed hydrophobic residues of the lysozyme refolding intermediates, thus minimizing hydrophobic-driven aggregation of the molecules. Importantly, results from this study show that the Eudragit-lysozyme bioconjugation does not compromise refolded protein structure, and that the polymer can be readily dissociated from the protein by ion exchange chromatography. The strategy was also applied to refolding of TGF-,1 and KGF-2. © 2009 American Institute of Chemical Engineers Biotechnol. Prog. 2009 [source] Photonic Shell-Crosslinked Nanoparticle Probes for Optical Imaging and MonitoringADVANCED MATERIALS, Issue 13 2009Nam S. Lee A pH-insensitive fluorophore is fabricated to give pH-driven responses through its covalent incorporation within a nanostructure derived from pH-responsive polymers. Fluorophore shell-crosslinked nanoparticles (SCKs) demonstrate notable enhancement of photophysical properties in the physiological pH region. Fluorophore SCKs are designed to swell at higher pH values and shrink as the pH is lowered, producing high fluorescence versus low fluorescence outputs, respectively. [source] ,Smart' delivery systems for biomolecular therapeuticsORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 3 2005PS Stayton Structured Abstract Authors ,, Stayton PS, El-Sayed MEH, Murthy N, Bulmus V, Lackey C, Cheung C, Hoffman AS Objective ,, There is a strong need for drug delivery systems that can deliver biological signals from biomaterials and tissue engineering scaffolds, and a particular need for new delivery systems that can efficiently deliver biomolecules to intracellular targets. Viruses and pathogens have evolved potent molecular machinery that sense the lowered pH gradient of the endosomal compartment and become activated to destabilize the endosomal membrane, thereby enhancing protein or DNA transport to the cytoplasmic compartment. A key feature of many of these biological delivery systems is that they are reversible, so that the delivery systems are not directly toxic. These delivery systems have the ability to change their structural and functional properties and thus display remarkable ,smart' material properties. The objective of this presentation is to review the initial development of smart polymeric carriers that mimic these biological delivery systems and combine similar pH-sensitive, membrane-destabilizing activity for the delivery of therapeutic biomolecules. Design ,, We have developed new ,smart' polymeric carriers to more effectively deliver and broaden the available types of biomolecular therapeutics. The polymers are hydrophilic and stealth-like at physiological pH, but become membrane-destabilizing after uptake into the endosomal compartment where they enhance the release of therapeutic cargo into the cytoplasm. They can be designed to provide a range of pH profiles and membrane-destabilizing activities, allowing their molecular properties to be matched to specific drugs and loading ranges. A versatile set of linker chemistries is available to provide degradable conjugation sites for proteins, nucleic acids, and/or targeting moieties. Results ,, The physical properties of several pH-responsive polymers were examined. The activity and pH profile can be manipulated by controlling the length of hydrophobic alkyl segments. The delivery of poly(propyl acrylic acid) (PPAA)-containing lipoplexes significantly enhanced wound healing through the interconnected effects of altered extracellular matrix organization and greater vascularization. PPAA has also been shown to enhance cytoplasmic delivery of a model protein therapeutic. Polymeric carriers displaying pH-sensitive, membrane-destabilizing activity were also examined. The pH profile is controlled by the choice of the alkylacrylic acid monomer and by the ratio of the carboxylate-containing alkylacrylic acid monomer to alkylacrylate monomer. The membrane destabilizing activity is controlled by the lengths of the alkyl segment on the alkylacrylic acid monomer and the alkylacrylate monomer, as well as by their ratio in the final polymer chains. Conclusion ,, The molecular mechanisms that proteins use to sense and destabilize provide interesting paradigms for the development of new polymeric delivery systems that mimic biological strategies for promoting the intracellular delivery of biomolecular drugs. The key feature of these polymers is their ability to directly enhance the intracellular delivery of proteins and DNA, by destabilizing biological membranes in response to vesicular compartment pH changes. The ability to deliver a wide variety of protein and nucleic acid drugs to intracellular compartments from tissue engineering and regenerative scaffolds could greatly enhance control of important processes such as inflammation, angiogenesis, and biomineralization. [source] | |||||||||||||