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• 1120-71-4 1,3-propanesultone 
• 3845-76-9 N-[3-(dimethylamino)propyl]acrylamide 

Relevant academic research and scientific papers

Conjugation with betaine: A facile and effective approach to significant improvement of gene delivery properties of PEI

Herein, we developed a new gene delivery vector by grafting a betaine monomer (N,N-dimethyl(acrylamidopropyl)ammonium propane sulfonate, DMAAPS) onto 25 KDa polyethylenimine (PEI 25K) via the Michael addition reaction. The graft ratio for betaine on PEI polymer could be readily controlled, and in this study three PEI-betaine conjugates PEI-DMAAPS23%, PEI-DMAAPS55%, and PEI-DMAAPS95% were prepared with their graft ratios of 23, 55, and 95%, respectively. The PEI-betaine conjugates exhibited much lower protein adsorption and cytotoxicities compared with PEI 25K, and they also showed little or no hemolytic effect. Moreover, the PEI-betaine conjugates display satisfactory DNA condensation capability; and in the absence and presence of serum, PEI-DMAAPS23%/pEGFP and PEI-DMAAPS55%/pEGFP complexes exhibited remarkable gene transfection efficiencies determined by flow cytometry, which are in general several times higher than that of PEI 25K. With these favorable properties, the PEI-betaine conjugates hold great potential for use as efficient gene delivery vectors. This study suggests that the betaine monomer may serve as a biocompatible modifying agent and this facile strategy may provide a facile and effective way for constructing some other biocompatible materials.

Ratiometric fluorescent probe for alkaline phosphatase based on betaine-modified polyethylenimine via excimer/monomer conversion

Alkaline phosphatase (ALP) is an important diagnostic indicator for a number of human diseases since abnormal level of ALP is closely related to a variety of pathological processes; hence, the development of convenient and reliable assay methods for monitoring ALP is of great significance for medical sciences as well as biological diagnostics. Herein, we report the first ratiometric fluorescent sensing system for ALP. This sensing system consists of two components: the betaine-modified and positively charged polyethylenimine (PEI) and the negatively charged pyrene derivative containing one ALP-responsive phosphate group (Py-P, an aliphatic phosphate ester). In the absence of ALP, the two-component sensing system shows the excimer"s emission of Py-P, since Py-P molecules complex with the positively charged polyelectrolyte via electrostatic interactions, leading to the formation of pyrene excimers. While in the presence of ALP, the phosphate moieties are cleaved from Py-P molecules due to the enzymatic reaction, thereby destroying the electrostatic interactions; as a result, the system displays the monomer emission of Py-P. This assay system is operable in aqueous media with a very low detection limit of 0.1 U/mL. The system is capable of detecting ALP in such biological fluid as serum, and this strategy may provide a new and effective approach for designing ratiometric sensing systems for detecting other biomolecules.

Thermosensitive properties of semi-IPN gel composed of amphiphilic gel and zwitterionic thermosensitive polymer in buffer solutions containing high concentration salt

In this study, a semi-interpenetrating polymer network (semi-IPN) gel, which consists of an amphiphilic N,N-dimethylacrylamide-co-N-isopropylacrylamide (DMAA-co-NIPAM) gel and an interpenetrating zwitterionic thermosensitive poly(N-isopropylacrylamide-co-N,N-dimethyl(acrylamidopropyl)ammonium propane sulfonate) (poly(NIPAM-co-DMAAPS)) was prepared. The thermosensitive behavior of the semi-IPN gel was investigated in a buffer solution composed of a relatively high concentration of sodium chloride and sodium citrate as salts, and sodium dodecyl sulfate as a surfactant, which are generally used as a buffer solution in biochips. At low temperatures, the semi-IPN gel in the buffer solution was absolutely transparent; however, when the gel was heated, the gel became milky white or opaque without a large change in the gel size. The network of the transparent gel is homogeneous, whereas that of the opaque gel consists of coarse and dense parts. Such a structural change in the gel network was confirmed by the temperature dependence of the permeability of the buffer solution through the semi-IPN gel membrane. The permeability increased drastically when the gel became opaque because of heating.

Effects of specific anions on the relationship between the ion-adsorption properties of sulfobetaine gel and its swelling behavior

The adsorption of cations and anions from four different halide solutions, i.e., KF, KCl, KBr, and KI solutions, onto N,N-dimethyl(acrylamidopropyl)ammonium propane sulfonate (DMAAPS) gels prepared using various cross-linker concentrations was investigated at a variety of temperatures; the swelling degrees of the gel in these solutions were also examined. The amount of K+ adsorbed coincided with the adsorption of the anions (i.e., I-, Br-, Cl-, or F-) because of simultaneous adsorption of the cations and anions onto DMAAPS gel. The order of anions, which gave larger amount of K+ adsorbed onto the gel, was opposite that of the Hofmeister series, i.e., I- > Br- > Cl- > F-. Furthermore, the relationship between the degree of swelling of the gel and amount of K+ adsorbed onto the gel was elucidated. The data points laid on the same line for the same halide solution even at different cross-linker concentrations or temperatures. At smaller degrees of swelling, the amount of K+ adsorbed remained unchanged and then decreased gradually as the degree of swelling increased. In solutions containing anions with lower hydration ability, such as KI, the amount of K+ adsorbed decreased at larger degrees of swelling. In contrast, in solutions containing anions with higher hydration abilities, such as KCl, the adsorbed amount of K+ decreased at smaller degrees of swelling. Additionally, it was found that, in mixtures of these halide solutions, competitive adsorption of anions occurred. Anions with lower hydration abilities adsorbed more readily in the mixtures than in the single-anion solution. In contrast, anions with higher hydration abilities adsorbed less readily in the mixtures than in the single-anion solution.

Investigation of ion adsorption properties of sulfobetaine gel and relationship with its swelling behavior

The adsorption of cations and anions in nitrate solutions on N,N-dimethyl(acrylamidopropyl)ammonium propane sulfonate (DMAAPS) gels prepared using various cross-linker and monomer concentrations was investigated. The influence of the temperature and nitrate concentration on the adsorption properties of the gel was evaluated, demonstrating simultaneous adsorption of cations and anions. The amount of Zn2+adsorbed on the gel in Zn(NO3)2solution increased as the cross-linker and monomer concentrations used in the gel preparation increased. For the gel prepared using a higher cross-linker or monomer concentration, elevation of the temperature did not induce any significant change in the amount of Zn2+adsorbed on the gel. Furthermore, for the gel prepared using a lower cross-linker or monomer concentration, the amount of Zn2+adsorbed on the gel decreased significantly as the temperature increased. In addition, an interesting correlation between the degree of swelling of the gel and the amount of Zn2+adsorbed on the gel was found. As the degree of swelling decreased, the adsorption amount increased to eventually achieve a constant value.

Synthesis of highly stretchable, mechanically tough, zwitterionic sulfobetaine nanocomposite gels with controlled thermosensitivities

Novel nanocomposite (NC) gels with zwitterionic characteristics were prepared by in situ free-radical polymerization of sulfobetaine monomers in the presence of exfoliated clay platelets in aqueous media. Two specific sulfobetaine monomers, N,N-dimethyl(acrylamidopropyl)ammonium propanesulfonate and butanesulfonate, were selected on the basis of the interactions between the monomers and clay, which result in uniform aqueous solutions of low viscosity and gel formation without using an organic cross-linker. The resulting NC gels with polymer-clay network structures were insoluble in NaCl solution or hot water, unlike conventional physically cross-linked gels. Also, NC gels with high mechanical properties and well-controlled thermosensitivities were effectively prepared by copolymerization with a small amount of N,N-dimethylacrylamide. The copolymer NC gels were uniform and simultaneously showed high stretchability, tough mechanical properties, and well-defined upper critical solution temperature (UCST) phase-transitions. Furthermore, the tensile mechanical properties and UCST were controlled over a wide range by altering the clay concentration and copolymerization ratio.