Functional copolymers of N-isopropylacrylamide for bioengineering applications (original) (raw)
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Journal of Polymer Science Part A: Polymer Chemistry, 2004
Hydrogels responsive to both temperature and pH have been synthesized in the forms of sequential interpenetrating networks (IPNs) of N-isopropylacrylamide (NIPAAm) and sodium acrylate (SA) and compared with the crosslinked random copolymers of N-isopropylacrylamide and SA. Whereas the stimuli-sensitive behaviors of copolymer hydrogels were strongly dependent on the ionic SA contents, the IPN hydrogels exhibited independent swelling and thermal behaviors of each network component. The sequences and media in the synthesis of IPNs influenced the swelling capacities of the IPNs, but not the temperature or pH ranges at which the swelling changes occurred. In IPNs, a more expanded primary gel network during the synthesis of the secondary network contributed to the better swelling of the final IPNs. Both the swelling and thermal behaviors of the IPNs suggest that poly(N-isopropylacrylamide) and poly(sodium acrylate) are phase separated regardless of their synthesis conditions. The presence of the poly(sodium acrylate) network did not influence the temperature or the extent of phase transition of the poly(N-isopropylacrylamide) network in the IPNs, but did improve the thermal stability of the IPNs.
Hydrogels based on N-isopropylmethacrylamide and N-isopropylacrylamide
Advanced Technologies, 2018
Hydrogels are three-dimensional polymer networks which have the capacity to retain a large quantity of water or biological fluids in the swollen state. Thermosensitive hydrogels have received special attention of reserachers since they represent a parameter which frequently changes in chemical, biological and physiological systems. Thermosensitive hydrogels have the critical solution temperature, i.e. they exhibit a substantial change in volume with the temperature change. Homopolymers poly(N-isopropylmethacrylamide) (poly(NIPMAM)) and poly(N-isopropylacrylamide) (poly(NIPAM)) are thermosensitive materials which have lately become the subject of intensive study. Monomer N-isopropylmethacrylamide, NIPMAM, enters into copolymerization with monomer N-isopropylacrylamide, NIPAM, in order to create a system with a phase transition temperature approximate to the human body temperature. In literature data there is available information on the synthesis and characterization of microgels, nanogels and copolymers based on NIPMAM and NIPAM. These thermosensitive polymer materials are used in controlled drug delivery and protein immobilization.
Biomacromolecules, 2010
Novel thermoreversible copolymers of N-isopropylacrylamide (NIPAAm) with collagenase-sensitive solubility behavior were synthesized by radical polymerization of poly(NIPAAm-co-NASI) and nucleophilic substitution of custom peptides GAPGL-NH 2 and GAPGLF-NH 2 . The materials were characterized by nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography in conjunction with static light scattering, differential scanning calorimetry (DSC), and cloud point determination. Successful synthesis and specific degradation by collagenase above and below the material LCST was confirmed by NMR. The LCST behavior of the polymers was affected by collagenase. The LCST of the copolymers, as measured by cloud point determination, increased by 1 and 9°C, respectively, after enzymatic degradation. DSC thermographs indicated increased polymer solubility after enzymatic degradation because of a reduced energy of gelation. These results demonstrate the significant impact of a single amino acid on the LCST behavior of thermosensitive copolymers. Furthermore, the results suggest that comonomers in similar systems could be designed to elicit phase transitions or conformation changes in response to a variety of enzymes for which the substrate structure is known.
Polymer, 2003
Temperature sensitive polymer hydrogels are being extensively studied because of their potential applications in biomedical, robotics, and chemical industry. However, major hurdles in their development have been their slow response, low efficiency, and poor mechanical properties. One of the main reasons for these shortcomings is the difficulty of processing them into mechanically fine structures in polymer gel form. In this work, a novel approach has been developed to process temperature sensitive copolymers based on acrylamide into mechanically stable thin films. A series of temperature sensitive random linear copolymers of N-tert-butylacrylamide (NTBA) and acrylamide (Am) were synthesized by solution polymerization method, using regulated dosing of comonomer Am having a higher reactivity ratio ðr Am ¼ 1:5Þ than NTBA ðr NTBA ¼ 0:5Þ: Copolymers with varying feed ratios of NTBA and Am (80:20 to 20:80 mol%) were synthesized and characterized. The actual incorporation of less reactive comonomer NTBA was found to be lower than the feed and was found to vary between 75 mol% with feed of 80 and 11 mol% for a feed of 20%. Linear copolymer with 40:60 feed ratio of NTBA and Am monomers, with actual incorporation of NTBA to the extent of 27 mol%, was selected for processing. The copolymer films of thickness in the range of 10-200 microns could be obtained from aqueous solution in the presence of citric acid or 1,2,3,4-butane tetracarboxylic acid as crosslinkers and sodium hypophosphite as catalyst. Subsequently, the films were crosslinked at 150-160 8C to obtain mechanically strong insoluble films. The crosslinks were formed between reactive amide side groups of the acrylamide moiety of the polymer and the carboxylic acid group of the crosslinker. The transition temperatures of the crosslinked films were found to shift towards the lower temperature from 37 8C (in linear copolymer) to 22-25 8C. High surface to volume ratio of the prepared films lead to significant increase in swelling percentage from 490 to 2980% and faster response time from 1280 min (in the first cycle) to 5 min compared to polymerized-gel samples (2 mm disc) of the same composition.
N-isopropylacrylamide-based Copolymers with Time-dependent LCST for a Bioresorbable Carrier
MRS Proceedings, 2004
To develop a new class of in situ-forming, injectable, and biodegradable polymeric biomaterials based on time-dependent lower critical solution temperature (LCST) properties for localized delivery, copolymers of N-isopropylacrylamide (NIPAAm), 2-hydroxyethyl methacryl lactate (HEMA-lactate) and acrylic acid (AAc) were prepared with varying mole ratios of monomers. The copolymers showed LCST and gelation properties below body temperature in 0.1 N PBS solution of pH 7.4. The LCST and gelation temperature of the copolymers decreased as the HEMA-lactate content of the copolymers was increased. The copolymers also showed time-dependent LCST and gelation properties in 0.1 N PBS solution of pH 7.4 owing to hydrolysis of HEMA-lactate. Hydrolysis of HEMA-lactate caused the polymers to be more hydrophilic, resulting in an increase in LCST and gelation temperature. All the polymers with about 6 mol % AAc exhibited LCST and gelation temperature above body temperature after complete hydrolysis of HEMA-lactate.
Journal of Polymer Science Part A: Polymer Chemistry, 2010
Novel bioengineering functional terpolymers were synthesized by complex-radical terpolymerization of N-isopropylacrylamide (NIPA), 3,4-dihydro-2H-pyran (DHP) and maleic anhydride (MA) with a,a 0-azoisobisbutyronitrile (AIBN) as a radical initiator in 1,4-dioxane at 65 C under nitrogen atmosphere. Structure compositions and composition-property relationships of terpolymers, and the monomer reactivity ratios were investigated by 1 H (13 C) NMR spectroscopy, DSC and TGA thermal analysis. The monomer reactivity ratios were determined by modified methods of Jaacks and Kelen-Tudö s using 1 H-NMR analysis data: r 1 ¼ 1.14 and r 2 ¼ 0.06 (by 1 H-NMR) and r 1 ¼ 1.07 and r 2 ¼ 0.04 (by N analysis) for NIPA (M 1) and MA…DHP (M 2) monomer-monomer complex pair. An a,x-hydroxy-methoxypolyethylene oxide branched derivative was synthesized by grafting (esterification) of anhydride units of the terpolymer. Investigation into the factors affecting the antitumor activity revealed that terpolymers containing a combination of H-bonded ionizable amide and carboxylic groups exhibited higher antitumor activity, towards SCLC cancer cells. V
Journal of Research Updates in Polymer Science, 2014
The study presents a set of copolymers synthesis based on N-isopropylacrylamide, 2-dimethylaminoethyl methacrylate and itaconic acid comonomers found in different gravimetric ratio, acquired through polymerization in water in the presence of ammonium persulfate as radical initiator. The purpose was to prepare polymeric structure with dual sensitivity to temperature and pH respectively, and able as well to ensure intramolecular strategies for coupling applications of inorganic or bioactive compounds. The polymers composition was confirmed by FTIR and 1 H-NMR spectra. The thermal stability of the polymeric compounds was evaluated, and SEM investigations of the polymer morphology are also presented. The polymers dispersions were characterized from the viewpoint of their hydrodynamic radius, zeta potential and conductivity.
Biomolecules
Vanillin was used to synthesize a new derivative with an active aldehyde group and response to pH. It is named 2-((diethylamino) methyl)-4-formyl-6-methoxyphenyl acrylate, abbreviated to DEAMVA. The chemical structures were evaluated by 1H, 13C nuclear magnetic resonance (NMR), infrared (IR), and UV-Vis-spectroscopy, and all results demonstrated good statement. In order to achieve the dual responsive behavior thermo-pH with functionality, free radical polymerization of N-isopropylacrylamide with DEAMVA in different molar ratios (5, 10, 15 mol%) has been used, with azobisisobutyronitrile (AIBN) as the initiator. The chemical structure of the polymers was investigated by 1H NMR and IR. The dual responsive functional copolymer was exposed to a grafted process with tryptophan and tyrosine, both of which were also evaluated by 1HNMR and IR. Copolymers before and after grafting were physically investigated by size exclusion chromatography (SEC) for estimation of the molecular weight, the ...
Hydrogels, having nanomaterials (e.g. nanoparticles and nanorods) incorporated inside their polymeric meshes, are generally called hybrid gels/hydrogels. These assemblies combine the properties of both hydrogels and nanomaterials in one system. These responsive hybrid hydrogels, particularly polymerized N-isopropylacrylamide (PoNip) polymeric gels, have been extensively exploited for various multi-disciplinary applications in the literature over the past two decades because of their unique and exquisite particulars. Next generation assemblies have been prepared by using the smart nature of these gels toward the general incentives (e.g. temperature, ionic strength, and pH) in the fields of nanocatalysis, water purification, drug delivery, photonics, and optics. This review presents an overview of the PoNip hybrid assemblies engineered over the past 7 years i.e. 2010–2016 and extensively discusses the interaction of the incorporated nanomaterial with the polymeric chains of the hydrogels as it is the most significant factor which makes these assemblies attractive for all the associated applications. Moreover, this article also describes the preparative routes, properties, classification, and applications of these hybrid hydrogels in the fields of medicine, environment, catalysis, and nanotechnology.