scholarly journals pH responsive highly branched poly(N-isopropylacrylamide) with trihistidine or acid chain ends

RSC Advances ◽  
2016 ◽  
Vol 6 (75) ◽  
pp. 71345-71350 ◽  
Author(s):  
T. Swift ◽  
J. Lapworth ◽  
K. Swindells ◽  
L. Swanson ◽  
S. Rimmer
Keyword(s):  
Ph Responsive ◽  
Thermally Responsive ◽  
Isopropyl Acrylamide ◽  
End Groups

Thermally responsive highly branched poly(N-isopropyl acrylamide)s (HB-PNIPAM) were prepared and end-functionalised to give polymers with acid or trihistidine end groups. ​The ionisation of the end groups affects the swelling of desolvated globules.

scholarly journals Multivalent dendritic polyglycerolamine with arginine and histidine end groups for efficient siRNA transfection

2015 ◽  
Vol 11 ◽  
pp. 763-772 ◽  
Author(s):  
Fatemeh Sheikhi Mehrabadi ◽  
Hanxiang Zeng ◽  
Mark Johnson ◽  
Cathleen Schlesener ◽  
Zhibin Guan ◽  
...  
Keyword(s):  
Amino Acid ◽  
Transfection Efficiency ◽  
Endosomal Escape ◽  
Primary Amines ◽  
Ph Responsive ◽  
3T3 Cells ◽  
Sirna Transfection ◽  
Efficient Delivery ◽  
End Groups ◽  
Nih 3T3

The success of siRNA-based therapeutics highly depends on a safe and efficient delivery of siRNA into the cytosol. In this study, we post-modified the primary amines on dendritic polyglycerolamine (dPG-NH2) with different ratios of two relevant amino acids, namely, arginine (Arg) and histidine (His). To investigate the effects from introducing Arg and His to dPG, the resulting polyplexes of amino acid functionalized dPG-NH2s (AAdPGs)/siRNA were evaluated regarding cytotoxicity, transfection efficiency, and cellular uptake. Among AAdPGs, an optimal vector with (1:3) Arg to His ratio, showed efficient siRNA transfection with minimal cytotoxicity (cell viability ≥ 90%) in NIH 3T3 cells line. We also demonstrated that the cytotoxicity of dPG-NH2 decreased as a result of amino acid functionalization. While the incorporation of both cationic (Arg) and pH-responsive residues (His) are important for safe and efficient siRNA transfection, this study indicates that AAdPGs containing higher degrees of His display lower cytotoxicity and more efficient endosomal escape.

scholarly journals Thermally responsive polymeric hydrogel brushes: synthesis, physical properties and use for the culture of chondrocytes

2006 ◽  
Vol 4 (12) ◽  
pp. 117-126 ◽  
Author(s):  
John Collett ◽  
Aileen Crawford ◽  
Paul V Hatton ◽  
Mark Geoghegan ◽  
Stephen Rimmer
Keyword(s):  
Crosslink Density ◽  
Cell Attachment ◽  
Viable Cell ◽  
Contact Angles ◽  
Polymer Chains ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Thermally Responsive ◽  
Isopropyl Acrylamide ◽  
Responsive Polymer

Hydrogel brushes are materials composed of a water-swollen network, which contains polymer chains that are grafted with another polymer. Using a thermally responsive polymer, poly( N -isopropyl acrylamide) (polyNIPAM), as the graft component we are able to maintain the critical solution temperature ( T crit ), independent of the overall composition of the material, at approximately 32°C. The change in swelling at T crit is a function of the amount of polyNIPAM in the system. However, there is a much smaller change in the surface contact angles at T crit . PolyNIPAM-based materials have generated considerable interest, as ‘smart’ substrates for the culture of cells and here, we show the utility of hydrogel brushes in cell culture. Chondrocytes attached to the hydrogel brushes and yielded viable cell cultures. Moreover, the chondrocytes could be released from the hydrogel brushes without the use of proteases by reducing the temperature of the cultures to below T crit to induce a change in the conformation of the polyNIPAM chain at T crit . The importance of the crosslink hydrogel component is illustrated by significant changes in cell attachment/cell viability as the crosslink density is changed.

Synthesis and Lcst Behavior of Thermally Responsive Poly(N-Isopropylacrylamide)/Layered Silicate Nanocomposites

1996 ◽  
Vol 457 ◽  
Author(s):  
Phillip B. Messersmith ◽  
F. Znidarsich
Keyword(s):  
Aqueous Suspension ◽  
Layered Silicate ◽  
Polymer Nanocomposite ◽  
Solution Temperature ◽  
Stimuli Responsive ◽  
Thermally Responsive ◽  
Isopropyl Acrylamide ◽  
Lcst Behavior ◽  
Hydrogel Composites

ABSTRACTStimuli responsive polymeric hydrogel composites were synthesized by room temperature copolymerization of N-isopropyl acrylamide and methylene bisacrylamide (crosslinking monomer) in an aqueous suspension of Na-montmorillonite. Hydrogels containing 3.5 weight % of montmorillonite exhibited a lower critical solution temperature (LCST) similar to unmodified PNIPAM hydrogel (approximately 32°C), and underwent a reversible 60–70% volume shrinkage when heated from ambient temperature to above the LCST. However, hydrogels containing 10 weight% montmorillonite did not exhibit a measurable LCST, and underwent considerably less shrinkage when heated. A solvent exchange reaction was used to replace the water with an acrylic monomer, which was polymerized in-situ to create a delaminated montmorillonite/polymer nanocomposite.

scholarly journals pH-Responsive Non-Ionic Diblock Copolymers: Ionization of Carboxylic Acid End-Groups Induces an Order-Order Morphological Transition

2014 ◽  
Vol 127 (4) ◽  
pp. 1295-1299 ◽  
Author(s):  
Joseph R. Lovett ◽  
Nicholas J. Warren ◽  
Liam P. D. Ratcliffe ◽  
Marzena K. Kocik ◽  
Steven P. Armes
Keyword(s):  
Carboxylic Acid ◽  
Diblock Copolymers ◽  
Morphological Transition ◽  
Ph Responsive ◽  
End Groups

scholarly journals pH-Responsive Non-Ionic Diblock Copolymers: Ionization of Carboxylic Acid End-Groups Induces an Order-Order Morphological Transition

2014 ◽  
Vol 54 (4) ◽  
pp. 1279-1283 ◽  
Author(s):  
Joseph R. Lovett ◽  
Nicholas J. Warren ◽  
Liam P. D. Ratcliffe ◽  
Marzena K. Kocik ◽  
Steven P. Armes
Keyword(s):  
Carboxylic Acid ◽  
Diblock Copolymers ◽  
Morphological Transition ◽  
Ph Responsive ◽  
End Groups

scholarly journals Probing the Folding of Peptide–Polymer Conjugates Using the π-Dimerization of Viologen End-Groups

2020 ◽  
Vol 02 (02) ◽  
pp. 143-148
Author(s):  
Ronja Otter ◽  
Pol Besenius
Keyword(s):  
Self Assembly ◽  
Optical Probe ◽  
Intermediate Structure ◽  
Reduction Step ◽  
Ph Responsive ◽  
Polymer Conjugates ◽  
Polymer Conjugate ◽  
Hydrogel Matrix ◽  
Close Proximity ◽  
End Groups

The synthesis of a foldable viologen-functionalized peptide–polymer conjugate is presented. The ABA-type triblock conjugate with a PEG polymer was capped with a FHFHF pentapeptide sequence and further modified with a viologen building block at both chain ends. The pH-responsive peptide domains fold into an intermediate structure inducing close proximity of the viologen units, which upon a reduction step form π-dimers of the radical cation. Overall the intramolecular folding and intermolecular self-assembly process leads to the formation of supramolecular nanorods. Mixing of viologen-peptide–polymer conjugates with unfunctionalized conjugates leads to crosslinking of the nanorods and hydrogels with a tunable content of viologen end groups. π-Dimerization in the gels induces a deep purple color, which is used as an optical probe to monitor the diffusion of molecular oxygen through the hydrogel matrix.

Thermosensitive Nanocontainers Prepared from Poly(N-isopropylacrylamide-co-N-(hydroxylmethyl)acrylamide)-g-Poly(lactide)

2006 ◽  
Vol 6 (9) ◽  
pp. 2896-2901 ◽  
Author(s):  
Yan Zhang ◽  
Wuli Yang ◽  
Changchun Wang ◽  
Wei Wu ◽  
Shoukuan Fu
Keyword(s):  
Self Assembly ◽  
Solution Temperature ◽  
Temperature Sensitive ◽  
Critical Solution Temperature ◽  
Spherical Structure ◽  
Thermally Responsive ◽  
Transmission Electron ◽  
Isopropyl Acrylamide ◽  
Fundamental Research ◽  
Spatial Specificity

Thermally-responsive graft copolymer of poly(N-isopropylacrylamide-co-N-(hydroxylmethyl)acrylamide)-g-poly(lactide) was synthesized by ring-opening polymerization of D,L-lactide (LA). The polymerization was initiated by the hydroxy group of poly(N-isopropyl acrylamide-co-N-(hydroxylmethyl)acrylamide), using stannous octoate as catalyst. The resulting polymer was temperature-sensitive and the lower critical solution temperature (LCST) was affected by their composition. The chemical structure and physical properties of the grafted copolymers were investigated by various methods. Nanocontainers formed from the self-assembly of poly(N-isopropylacrylamide-co-N-(hydroxylmethyl) acrylamide)-g-poly(lactide) were characterized by transmission electron microscopy (TEM), and a spherical structure was observed. Dynamic light scattering (DLS) results indicate that the particle size increased with the increase of polylactide content in the copolymer. The properties of this polymer are interesting for both industrial application and fundamental research. In particular it will combine a spatial specificity in a passive manner and a temperature-responsive active targeting mechanism for drug delivery system.

A New Bio-Inorganic Nanocomposite Membrane for Glucose-Modulated Release of Insulin

2009 ◽  
Vol 1234 ◽  
Author(s):  
Claudia Regina Gordijo ◽  
Adam Jason Shuhendler ◽  
Xiao Yu Wu
Keyword(s):  
Insulin Release ◽  
Glucose Level ◽  
Release Rate ◽  
Glucose Concentration ◽  
Glucose Sensor ◽  
Fold Increase ◽  
Ph Responsive ◽  
Long Term Stability ◽  
Isopropyl Acrylamide

AbstractThis work focuses on the development of a new bio-inorganic nanocomposite glucose-responsive membrane to be applied as a single self-regulated platform for insulin delivery. Crosslinked bovine serum albumin (BSA)-based membranes were prepared containing impregnated pH-responsive poly(N-isopropyl acrylamide-co-methacrylic acid) nanoparticles (hydrogel NPs), glucose oxidase (GOx), catalase (CAT), with or without MnO2 NPs. The membrane acts as a glucose sensor and insulin release attenuator. In this system glucose is oxidized by GOx to produce gluconic acid, which regulates the permeability of the membrane to insulin. CAT and/or MnO2 NPs are introduced into the membrane in order to quench unwanted H2O2 produced by GOx turnover cycles, which can cause inactivation of GOx and toxicity. The glucose-modulated insulin release through the membrane is determined by alternating glucose concentration between 100 – 400 mg/dL (normal and hyperglycemic levels, respectively). The results show that the combination of CAT and MnO2 NPs in the membrane formulation leads to better efficiency in quenching the H2O2 and better long-term stability of GOx than using either alone. Very small amounts of insulin permeate though the membrane at the normal blood glucose level while a four-fold increase in the release rate is observed when glucose concentration is raised to a hyperglycemic level. The release rate of insulin drops when the glucose level is reduced to a normal value. These results demonstrate the self-regulated capability of the system.

Sign in / Sign up

Export Citation Format

Share Document