Polydopamine Nanoparticle for Poly(N-Isopropylacrylamide)-Based Nanocomposite Hydrogel with Good Free-Radical-Scavenging Property

2016 ◽  
Vol 848 ◽  
pp. 94-98 ◽  
Author(s):  
Shu Qiang Xiong ◽  
Yan Wang ◽  
Jing Zhu ◽  
Zu Ming Hu ◽  
Jun Rong Yu
Keyword(s):  
Free Radical ◽  
Radical Scavenging ◽  
Antioxidant Property ◽  
Solution Temperature ◽  
Scavenge Activity ◽  
Initial Reaction ◽  
Critical Solution Temperature ◽  
Nanocomposite Hydrogels ◽  
Isopropyl Acrylamide

Nanocomposite hydrogels (NC gels) consisting of poly (N-Isopropyl acrylamide) (pNIPAM)/polydopamine nanoparticles (PDAPs) were prepared by in-situ-free-radical polymerization of N-isopropyl acrylamide in the presence of modified PDAP in aqueous solution. The composition of the NC gels could be controlled directly by altering the composition of the initial reaction mixture. The lower critical solution temperature (LCST) of the NC gels were studied by DSC, and the LCST of both of pure pNIPAM hydrogel and NC gels was at 34°C. Besides, the NC gels showed superior antioxidant property, and the ability to scavenge activity of NC gel was up to 70% with the addition of 6 wt% modified PDAP into pNIPAM.

scholarly journals Phenolic Profile and Antioxidant Evaluation of Mentha x Piperita L. (Peppermint) Extracts

2009 ◽  
Vol 4 (4) ◽  
pp. 1934578X0900400 ◽  
Author(s):  
H.J. Damien Dorman ◽  
Müberra Koşar ◽  
K Hüsnü C Başer ◽  
Raimo Hiltunen
Keyword(s):  
Free Radical ◽  
Rosmarinic Acid ◽  
High Performance ◽  
Radical Scavenging ◽  
Antioxidant Property ◽  
Free Radical Scavenging ◽  
Soluble Extract ◽  
Photodiode Array Detection ◽  
Mentha X Piperita ◽  
Soxhlet Apparatus

Seven extracts were prepared from Mentha x piperita (peppermint) leaves in sequence using a Soxhlet apparatus, viz. (40-60°) light petroleum (PE), dichloromethane (CH2Cl2), acetonitrile (ACN), ethyl acetate (EtOAc), methanol (MeOH), n-butanol and water (H2O) extracts. The phenolic and flavonoid content of each extract were estimated using spectrophotometric methods whilst a qualitative-quantitative analysis was made by reverse-phase high performance liquid chromatography coupled with photodiode array detection (HPLC-PDA). Each extract was assessed in a battery of six antioxidant-related assays so as to determine their iron(III) reductive, iron(II) chelating and free radical scavenging abilities. The MeOH-soluble extract contained the greatest content of total phenols and flavonoids based upon the Folin-Ciocalteu and 2-aminoethyl diphenylborate reagent data and HPLC-PDA analysis. Based upon the chromatographic and UV-spectral data, the leaves principally contained the cinnamic acid caffeic acid, the depside rosmarinic acid and flavonoids (flavones and flavanones). Eriocitrin (383.3 ± 2.2 mg/g extract) and rosmarinic acid (381.2 ± 1.9 mg/g extract) were the most abundant components identified within the leaves, whilst naringenin-7- O-glucoside (0.8 ± 0.01 mg/g extract) was the least abundant component identified being found only in the EtOAc-soluble extract. The EtOAc, ACN and H2O-soluble extracts demonstrated the most potent iron(III) reductive and 1,1′-diphenyl-2-picrylhydrayl, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) and hydroxyl free radical scavenging properties; however, the H2O and CH2Cl2-soluble extracts were the most potent extracts in the β-carotene-linoleic acid bleaching inhibition assay. In terms of iron(II) chelation – an important antioxidant property - the PE, MeOH and H2O extracts demonstrated moderate iron(II) chelating activity.

scholarly journals Lipid Lowering Activity and Free Radical Scavenging Effect of Cinnamomum tamala (Fam: Lauraceae)

1970 ◽  
Vol 1 (4) ◽  
pp. 93-96
Author(s):  
R Al-Mamun ◽  
A Hamid ◽  
MK Islam ◽  
JA Chowdhury ◽  
ATM Zafrul Azam
Keyword(s):  
Free Radical ◽  
Lipid Profile ◽  
Total Cholesterol ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Antioxidant Property ◽  
Free Radical Scavenging ◽  
Lipid Lowering ◽  
Increased Risk ◽  
Lowering Activity

Lipid profile is a blood test that measures the amount of lipids, or fats, in your blood. The lipids measured are usually total cholesterol, HDL-C, LDL-C and triglycerides. When levels of these lipids are abnormal, there is an increased risk of heart attack and stroke. In our study, we use methanol crude extract for lipid lowering activity on rabbit and found that lipid profile was reduced by 14.0, 1.0, 4.0 and 15.0 mg/dl for total cholesterol, HDL-C, LDL-C and triglyceride respectively after using the plant extract (dose 500mg/rabbit for 10 days); where atorvastatin (0.005mg/rabbit) was used as standard lipid lowering agent. We also focused on the antioxidant property of crude methanol extract. Here we also carried out free radical-scavenging activity study and found the IC50 value for C. tamala is 6.00 μg/ml where the standard antioxidant (ascorbic acid) gave the value of 3.21μg/ml. DOI: http://dx.doi.org/10.3329/ijns.v1i4.9735 IJNS 2011 1(4): 93-96

scholarly journals Antioxidant Activity of Quercetin: A Mechanistic Review

2016 ◽  
Vol 4 (12) ◽  
pp. 1134 ◽  
Author(s):  
Senay Ozgen ◽  
Ozgur Kivilcim Kilinc ◽  
Zeliha Selamoğlu
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Cardiovascular Diseases ◽  
Chemical Structure ◽  
Radical Scavenging ◽  
Antioxidant Property ◽  
Free Radical Scavenging ◽  
Polyphenolic Compounds ◽  
Structure And Properties ◽  
Treatment Of Diabetes

Flavones and flavonoids are known to have potent antioxidant activity due to intracellular free radical scavenging capacities. Flavonoids are found ubiquitously in plants as a member of polyphenolic compounds which share diverse chemical structure and properties. Quercetin is among the most efficient antioxidants of the flavonoids. The antioxidant property of quercetin has been highlighted in this review. These compounds have pivotal role in treatment of diabetes, cancers and some cardiovascular diseases.

Phase-separation immunoassays.

1987 ◽  
Vol 33 (9) ◽  
pp. 1509-1516 ◽  
Author(s):  
K Auditore-Hargreaves ◽  
R L Houghton ◽  
N Monji ◽  
J H Priest ◽  
A S Hoffman ◽  
...  
Keyword(s):  
Reaction Kinetics ◽  
Solid Phase ◽  
Specific Binding ◽  
Hepatitis B Surface Antigen ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Binding Reaction ◽  
Insoluble Polymer ◽  
Capture Antibody

Abstract Solid-phase-based immunoassays have traditionally been plagued by nonspecific binding to the solid phase and by slow reaction kinetics relative to reactants that are free to diffuse in solution. We have developed two novel immunoassays in which the solid phase is generated in situ after the specific binding reaction has occurred, thereby enhancing reaction kinetics and minimizing the opportunities for non-specific binding. In the first system, the capture antibody is conjugated to an organic monomer, polymerization of which to form insoluble polymer particles is initiated by a reaction involving free radicals. The amount of signal-labeled antibody incorporated into the resulting particles is directly proportional to the concentration of antigen. The principle is illustrated for the simultaneous assay of IgG and IgM in a single sample. In the second system, capture antibody is conjugated to a polymer, the solubility of which is a function of temperature. Specific binding is conducted below the critical solution temperature of the polymer, which is then separated from solution by increasing the temperature above the critical temperature. The incorporation of signal-labeled antibody into the precipitated polymer is directly proportional to the concentration of antigen. This principle is illustrated for the assay of hepatitis B surface antigen and Chlamydia trachomatis.

N-isopropylacrylamide-based Copolymers with Time-dependent LCST for a Bioresorbable Carrier

2004 ◽  
Vol 845 ◽  
Author(s):  
Bae Hoon Lee ◽  
Brent Vernon
Keyword(s):  
Body Temperature ◽  
Time Dependent ◽  
Solution Temperature ◽  
Gelation Temperature ◽  
Critical Solution Temperature ◽  
New Class ◽  
Polymeric Biomaterials ◽  
Localized Delivery ◽  
Hydrolysis Of

ABSTRACTTo 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.

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.

Substituent Effects on a Photo-Induced Alternation of the Lower Critical Solution Temperatures of Poly(N-isopropylacrylamide) with Azobenzene Units

2001 ◽  
Vol 710 ◽  
Author(s):  
Haruhisa Akiyama ◽  
Nobuyuki Tamaoki
Keyword(s):  
Free Radical ◽  
Visible Light ◽  
Lower Critical Solution Temperature ◽  
Water Solubility ◽  
Substituent Effects ◽  
Ultra Violet ◽  
Wettability Alteration ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Soluble Polymers

ABSTRACTWe synthesized copolymers of N-isopropylacrylamide (NIPAM) and azobenzene-containing acrylates or acrylamides by free radical polymerization, and investigated the water solubility of these polymers upon irradiation with ultra-violet and visible light. The solubility depended on concentration and structure of photoreactive azobenzene unit in the polymers. The soluble polymers showed the lower critical solution temperature, which was varied along with light irradiation. Photo-induced large wettability alteration was observed in the film.

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