Microemulsion Polymerization. 3. Molecular Weight and Particle Size Distributions

Co, Carlos C.; Cotts, Patricia M.; Burauer, S.; Vries, Renko de; Kaler, Eric W.

doi:10.1021/ma001248b

Cited by 48 publications

(40 citation statements)

References 27 publications

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“…Discrepancy between sizes measured with TEM and DLS is not unusual, 48, 49 with some studies finding a 50% larger size using DLS. 48 Such variation is typically explained by the differences in the way each obtains particle size: TEM requires particles to be dehydrated and subjects them to high vacuum, while DLS determines an average hydrodynamic particle diameter of fully hydrated particles. However, the large difference in TEM and DLS measurements seen in the present study may not be explained by this reason alone.…”

Section: Discussionmentioning

confidence: 99%

Zwitterionic Chitosan–Polyamidoamine Dendrimer Complex Nanoparticles as a pH-Sensitive Drug Carrier

Liu

Yeo

2013

Mol. Pharmaceutics

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Polyamidoamine (PAMAM) dendrimers have been widely explored as carriers of therapeutics and imaging agents. However, amine-terminated PAMAM dendrimers is rarely utilized in systemic applications due to its cytotoxicity and risk of opsonization, caused by its cationic charges. Such undesirable effects may be mitigated by shielding the PAMAM dendrimer surface with polymers that reduce the charges. However, this shielding may also interfere with PAMAM dendrimers’ ability to interact with target cells, thus reducing cellular uptake and overall efficacy of the delivery system. Therefore, we propose to use zwitterionic chitosan (ZWC), a new chitosan derivative, which has a unique pH-sensitive charge profile, as an alternative biomaterial to modify the cationic surface of PAMAM dendrimers. Stable electrostatic complex of ZWC and PAMAM dendrimers was formed at pH 7.4, where the PAMAM dendrimer surface was covered with ZWC, as demonstrated by fluorescence spectroscopy and transmission electron microscopy. The presence of ZWC coating protected red blood cells and fibroblast cells from hemolytic and cytotoxic activities of PAMAM dendrimers, respectively. Confocal microscopy showed that the protective effect of ZWC disappeared at low pH as the complex dissociated due to the charge conversion of ZWC, allowing PAMAM dendrimers to enter cells. These results demonstrate that ZWC is able to provide a surface coverage of PAMAM dendrimers in a pH-dependent manner and, thus, enhance the utility of PAMAM dendrimers as a drug carrier to solid tumors with acidifying microenvironment.

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Section: Discussionmentioning

confidence: 99%

Zwitterionic Chitosan–Polyamidoamine Dendrimer Complex Nanoparticles as a pH-Sensitive Drug Carrier

Liu

Yeo

2013

Mol. Pharmaceutics

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“…A crosslinking agent, (EGDMA), was added to the solution followed by the addition of AIBN initiator. The reaction proceeded for 7 h. Different nanohydrogel samples were obtained with varying the (AAc) monomer concentrations, initiator, crosslinking agent 42, 43. The copolymer was purified using selective precipitation with excess acetone and diethyl ether to destabilize the micelles.…”

Section: Techniquesmentioning

confidence: 99%

Synthesis and characterization of pH‐sensitive crosslinked (NIPA‐co‐AAC) nanohydrogels copolymer

Elsaeed

Farag

Maysour

2011

J of Applied Polymer Sci

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A thermoresponsive polymeric nanohydrogels has been synthesized by inverse microemulsion polymerization of N-isopropylacrylamide (NIPA) and acrylic acid (AAc) using Aerosol (AOT) as a surfactant, ethylene glycol dimethacrylate (EGDMA) as a crosslinker, and 2,2 0 -azobisisobutyronitrile (AIBN) as initiator. The effect of concentration of AIBN, EGDMA, and NIPA/AAc weight ratio was investigated. The lower critical solution temperature (LCST) of poly (NIPA-co-AAC) can be manipulated to be 40 C and 45 C which was correlated to amount of AAc that was copolymerized with NIPA. FTIR, 1H NMR, TEM, and DSC characterized the nanohydrogels.

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“…A value of M w equal to 2 Â 10 6 was reported for the chain transfer reaction limited ST free radical polymerizations (Kukulj et al, 1998). Co et al (2001b) also obtained values of PDI (MWD) in the range of 1.0-1.1 in ST microemulsion polymerizations stabilized by dodecyltrimethylammonium bromide. Co et al (2001b) also obtained values of PDI (MWD) in the range of 1.0-1.1 in ST microemulsion polymerizations stabilized by dodecyltrimethylammonium bromide.…”

Section: Resultsmentioning

confidence: 55%

Particle Nucleation and Growth Mechanisms in Styrene Microemulsion Polymerization

Chern

Tang

2003

Polymer Reaction Engineering

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A water-insoluble dye was used to study nucleation and growth of particle nuclei in styrene microemulsion polymerizations, stabilized by sodium dodecyl sulfate/1-pentanol and initiated by sodium persulfate (SPS). Both the rate of polymerization and concentration of latex particles increase with an increase in the initial SPS concentration ([SPS] 0 ). Least-squares best fitting experimental data with a modified Morgan-Nomura model leads to the conclusion that the limited flocculation of latex particles plays an important role in the reaction system. The weight percentage of dye incorporated into latex particles y Dedicated to Dr. Gary W. Poehlein in token of respect and gratitude.(P dye ) increases with the progress of polymerization. This implies that particle nucleation takes place continuously throughout the reaction. At constant monomer conversion, P dye decreases with increasing [SPS] 0 , which is attributed to the increased probability of particle formation in the aqueous phase with [SPS] 0 . Measurements of zeta potential of latex particles and polymer molecular weight were also conducted to gain a better understanding of polymerization mechanisms and kinetics.

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Microemulsion Polymerization. 3. Molecular Weight and Particle Size Distributions

Cited by 48 publications

References 27 publications

Zwitterionic Chitosan–Polyamidoamine Dendrimer Complex Nanoparticles as a pH-Sensitive Drug Carrier

Zwitterionic Chitosan–Polyamidoamine Dendrimer Complex Nanoparticles as a pH-Sensitive Drug Carrier

Synthesis and characterization of pH‐sensitive crosslinked (NIPA‐co‐AAC) nanohydrogels copolymer

Particle Nucleation and Growth Mechanisms in Styrene Microemulsion Polymerization

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