Manipulation of the rate of hydrolysis of polymer-drag conjugates: the degree of hydration

Pitt, Colin G.; Shah, S.S.

doi:10.1016/0168-3659(94)00098-f

Cited by 23 publications

(20 citation statements)

References 7 publications

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“…This leads to an enhanced water uptake and a distinctive increase of the hydrolysis rate. Similar findings were also proposed by Pitt and Shah who showed that hydrolytic cleavage reactions are accelerated if polymeric networks become more hydrophilic during the hydrolysis …”

Section: Resultssupporting

confidence: 89%

Dual‐Responsive Polydimethylsiloxane Networks

Giebler

Radl

Ast

et al. 2018

J. Polym. Sci. Part A: Polym. Chem.

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Exploiting the salient features of o‐nitrobenzyl chemistry, this work aims at the preparation of polydimethylsiloxane networks that undergo well‐defined bond cleavage in response to either UV light or different pH values as external trigger. Polydimethylsiloxane (PDMS) oligomers with terminal anhydride groups are thermally crosslinked in the presence of a bi‐functional epoxy monomer containing a photolabile o‐nitrobenzyl ester (o‐NBE) group. The susceptibility of the ester groups toward hydrolytic cleavage reactions is used for a pH‐triggered network degradation. Sol–gel analysis confirms that the degradation time can be easily controlled by the base concentration over different time scales varying between hours and weeks. Along with classical ester hydrolysis, photoinduced degradation of the elastomeric networks is carried out by photoisomerization and cleavage of the o‐NBE links upon exposure with UV light. Positive‐tone patterns with a structure size of 100 μm are obtained by photolithographic techniques confirming the spatial control of solubility properties. However, by increasing the exposure dose, recrosslinking of the networks is observed due to side reactions of the primary photocleavage products. As the reformed crosslinks are less sensitive to ester hydrolysis, the side reactions are employed to inscribe negative‐tone microstructures in the PDMS network. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2319–2329

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Section: Resultssupporting

confidence: 89%

Dual‐Responsive Polydimethylsiloxane Networks

Giebler

Radl

Ast

et al. 2018

J. Polym. Sci. Part A: Polym. Chem.

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“…Pitt and Shah have used this dependence of the hydrolytic rate on hydration to engineer zero‐order release kinetics 42. They tested four hydrogel‐forming copolymers with varying proportions of 2‐ p ‐nitrobenzoxyethyl methacrylate (NBEMA) and methoxydiethoxyethyl methacrylate (MDEEMA) for the release of p ‐nitrobenzoic acid.…”

Section: Release Of the Drug From The Polymer–drug Conjugatementioning

confidence: 99%

Release from polymeric prodrugs: Linkages and their degradation

D'Souza

Topp

2004

Journal of Pharmaceutical Sciences

132

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“…4 Polymeric networks containing side-chain poly(ethylene glycol) (PEG) molecules and ionic moieties are considered to be high-value polymeric materials, because of their potential use as biocompatible materials in medical applications. 14,15 These materials render the system responsive to pH changes in the surrounding environment and also aid in the formation of intramolecular hydrogen bonding between oxygen in the PEG chain and hydrogen atom of ionic moieties. The pK a of poly(acrylamidoglycolic acid) (PAGA) is 3.1, 16 so that carboxylic groups of PAGA are nonionized under lower acidic conditions, and the system is able to form hydrogen bonds within the network.…”

Section: Introductionmentioning

confidence: 99%

“…By the end of 5 h, about 98% of the drug entrapped was released. 15 In the present work, we prepared MGs composed on PMMA, PAGA, and methoxy PEG monomaleate (MPEG) [poly(MMA-co-AGA-co-MPEG)] crosslinked by EGDMA. The in vitro release studies of MGs were performed at 37 C (pH, 7.4 and 1.2).…”

Section: Introductionmentioning

confidence: 99%

“…Biodegradable and biocompatible matrices derived from block and graft copolymers have recently attracted much attention, not only because of their potential for CR applications, but also due to their biocompatible and biodegradable properties 4. Polymeric networks containing side‐chain poly(ethylene glycol) (PEG) molecules and ionic moieties are considered to be high‐value polymeric materials, because of their potential use as biocompatible materials in medical applications 14, 15. These materials render the system responsive to pH changes in the surrounding environment and also aid in the formation of intramolecular hydrogen bonding between oxygen in the PEG chain and hydrogen atom of ionic moieties.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

PMMA‐based microgels for controlled release of an anticancer drug

Rao

Chung

Reddy

et al. 2008

J of Applied Polymer Sci

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Methyl methacrylate (MMA), methoxy poly (ethylene glycol) monomaleate (MPEG), and acrylamidoglycolic acid (AGA) terpolymeric microgels (MGs) have been synthesized by free-radical surfactant-free emulsion polymerization. MPEG was synthesized from maleic anhydride and methoxy poly(ethylene glycol). The MGs were crosslinked with ethylene glycol dimethacrylate, and the chemical crosslinking was confirmed by Fourier transform infrared spectroscopy. 5-Fluorouracil (5-FU), a model anticancer drug, has been loaded into the MGs by in situ and adsorption methods. Empty as well as drug-loaded MGs were then characterized by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and Xray diffraction (XRD). DSC and XRD studies indicated a molecular level dispersion of the drug in PMMA MGs during in situ loading. TEM images showed the formation of spherical MGs. In vitro release of 5-FU from the crosslinked poly(MMA-co-AGA-co-MPEG) MGs were investigated at both pH 7.4 and 1.2 buffer medium that controlled release of the drug up to $ 18 h. Both the encapsulation efficiency and the release patterns were dependent on the amount of crosslinking agent and the amount of drug loaded.

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Manipulation of the rate of hydrolysis of polymer-drag conjugates: the degree of hydration

Cited by 23 publications

References 7 publications

Dual‐Responsive Polydimethylsiloxane Networks

Dual‐Responsive Polydimethylsiloxane Networks

Release from polymeric prodrugs: Linkages and their degradation

PMMA‐based microgels for controlled release of an anticancer drug

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