Unusual pH-Dependent Polarity Changes in PAMAM Dendrimers:  Evidence for pH-Responsive Conformational Changes

Chen, Wei; Tomalia, Donald A.; Thomas, James L.

doi:10.1021/ma000791p

Cited by 192 publications

(190 citation statements)

References 24 publications

Supporting

Mentioning

180

Contrasting

Unclassified

Order By: Relevance

“…It can be postulated that at acidic pH the equilibrium will shift towards neutral form of the phenolic OH thus eliminating the ionic interactions between deprotonated phenolic OH and dendrimer, thereby releasing the free drug. Similar observations were reported previously where binding of polarity responsive probe 5-(di-methylamino)-1-napthalene sulfonic acid (DNS) with amine terminated PAMAM dendrimer was studied at several pH levels (22). Optimal binding was observed when both DNS and PAMAM dendrimers were in ionic forms.…”

Section: Drug Releasesupporting

confidence: 86%

Potential Oral Delivery of 7-Ethyl-10-Hydroxy-Camptothecin (SN-38) using Poly(amidoamine) Dendrimers

2008

View full text Add to dashboard Cite

Purpose-To investigate potential application of poly(amidoamine) (PAMAM) dendrimers for improving the delivery of SN-38.Methods-Complexes of SN-38 with generation 4 amine terminated PAMAM dendrimers were synthesized with varying amounts of drug. Stability of the complexes as well as influence of complexation on permeability across and cellular uptake by Caco-2 cells was evaluated.Results-The complexes were stable at pH 7.4 and drug was released at pH 5. A tenfold increase in permeability and more than hundredfold increase in cellular uptake of the complexes with respect to free SN-38 was observed.Conclusions-Studies suggest that complexation with PAMAM dendrimers has the potential to improve the oral bioavailability of SN-38.

show abstract

Section: Drug Releasesupporting

confidence: 86%

Potential Oral Delivery of 7-Ethyl-10-Hydroxy-Camptothecin (SN-38) using Poly(amidoamine) Dendrimers

2008

View full text Add to dashboard Cite

show abstract

“…12 The LCSTs of HPEI10K-IBAm 1.0 and HPEI1.8K-IBAm 1.0 increased linearly with increasing the acidity of the solutions. Since the fully IBAm-terminated HPEIs still contained large amount of tertiary amines in the interior, protonating the interior might induce the expansion of the hyperbranched polymers due to the charge-charge repulsion induced by the protonated tertiary amines just like the PAMAM dendrimer, 31 which was supposed to be able to reduce the density of terminal IBAm groups and increase the LCST. 12 Moreover, the LCST of higher molecular-weight hyperbranched polymer was much more sensitive to the change of pH.…”

Section: Degree Of Amidation (Hpei10k)mentioning

confidence: 99%

Thermoresponsive hyperbranched polyethylenimines with isobutyramide functional groups

Liu

Chen

Shen

2007

J. Polym. Sci. A Polym. Chem.

View full text Add to dashboard Cite

“…There have been a number of different approaches to make small metal clusters. For example, Tomalia et al 29,30 reported the first synthesis of smaller gold particles under the context of making dendrimer metal nanocomposites. It was later found with these systems that tremendous optical limiting and time-resolved optical properties [31][32][33] could be obtained as well as new ideas for catalysis.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Optical Study of Small Gold Monolayer Protected Clusters: A Closer Look at Emission

et al. 2010

View full text Add to dashboard Cite

Monolayer-protected metal nanoclusters (MPCs) were investigated to probe their fundamental excitation and emission properties. In particular, gold MPCs were probed by steady-state and time-resolved spectroscopic measurements; the results were used to examine the mechanism of emission in relation to the excited states in these systems. In steady-state measurements, the photoluminescence of gold clusters in the range of 25 to 140 atoms was considerably stronger relative to larger particle analogues. The increase in emission efficiency (for Au 25 , Au 55 , and Au 140 on the order of 10 -5) over bulk gold may arise from a different mechanism of photoluminescence, as suggested by measurements on larger gold spheres and rods. Results of fluorescence upconversion found considerably longer lifetimes for smaller gold particles than for larger particles. Measurements of the femtosecond transient absorption of the smaller clusters suggested dramatically different behavior than what was observed for larger particles. These results, combined with the result of a new bleach band in the transient absorption signal (which is presumably due to an unforeseen ground state absorption), suggest that quantum size effects and associated discrete molecular-like state structure play a key role in enhanced visible fluorescence of small clusters.

show abstract

Unusual pH-Dependent Polarity Changes in PAMAM Dendrimers: Evidence for pH-Responsive Conformational Changes

Cited by 192 publications

References 24 publications

Potential Oral Delivery of 7-Ethyl-10-Hydroxy-Camptothecin (SN-38) using Poly(amidoamine) Dendrimers

Potential Oral Delivery of 7-Ethyl-10-Hydroxy-Camptothecin (SN-38) using Poly(amidoamine) Dendrimers

Thermoresponsive hyperbranched polyethylenimines with isobutyramide functional groups

Ultrafast Optical Study of Small Gold Monolayer Protected Clusters: A Closer Look at Emission

Contact Info

Product

Resources

About