Tuning hydrogel properties and function using substituent effects

Kohman, Richie E.; Cha, Chaenyung; Zimmerman, Steven C.; Kong, Hyunjoon

doi:10.1039/c001548b

Cited by 13 publications

(13 citation statements)

References 16 publications

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“…Sodium salt is a regulator of blood, body fluids, and certain metabolic functions, and an increase in local sodium concentration has been linked to tumor malignancy in human brain and breast tissues . Finally, variation in pH can induce sol–gel transition and in tumor and inflammatory tissues the local environment is more acidic than in normal tissues . Therefore, materials that undergo a physicochemical response to changes in temperature, salt concentration, and pH may be of great interest in many biomedical applications.…”

mentioning

confidence: 99%

Chitosan-PEG Hydrogel with Sol-Gel Transition Triggerable by Multiple External Stimuli

Tsao

Hsiao

Zhang

et al. 2014

Macromol. Rapid Commun.

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Smart hydrogels play an increasingly important role in biomedical applications, since materials that are both biocompatible and multi‐stimuli‐responsive are highly desirable. A simple, organic solvent‐free method is presented to synthesize a biocompatible hydrogel that undergoes a sol–gel transition in response to multiple stimuli. Methoxy‐poly(ethylene glycol) (mPEG) is modified into carboxylic‐acid‐terminated‐methoxy‐poly(ethylene glycol) (mPEG‐acid), which is then grafted onto chitosan via amide linkages yielding mPEG‐g‐chitosan. Grafting of mPEG onto hydrophobic chitosan imparts hydrophilic properties to the resultant polymer. The mPEG‐g‐chitosan gel exhibits a controllable multi‐stimuli‐responsive property. The balance between hydrophilicity and hydrophobicity is believed to confer mPEG‐g‐chitosan with stimuli‐responsive behavior. The effect of salt concentration, solute concentration, temperature, and pH on the sol–gel transition of mPEG‐g‐chitosan is evaluated and the underlying mechanisms of mPEG‐g‐chitosan polymer packing and gelation property is discussed.

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mentioning

confidence: 99%

Chitosan-PEG Hydrogel with Sol-Gel Transition Triggerable by Multiple External Stimuli

Tsao

Hsiao

Zhang

et al. 2014

Macromol. Rapid Commun.

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“…Notably, we have synthesized acrylamide-based crosslinkers to introduce additional physical crosslinks, i.e., hydrogen bonds. It has been shown that networks composed of amide bonds exhibit much higher stiffness and stability compared to their ester analogs 18 , 19 . This aspect is particularly beneficial for true 3D nano- and microstructures having freely suspended segments.…”

Section: Resultsmentioning

confidence: 99%

Adding chemically selective subtraction to multi-material 3D additive manufacturing

Gräfe

Wickberg²,

Zieger

et al. 2018

Nat Commun

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Existing photoresists for 3D laser lithography that can be removed after development in a subtractive manner typically suffer from harsh cleavage conditions. Here, we report chemoselectively cleavable photoresists for 3D laser lithography based on silane crosslinkers, allowing the targeted degradation of 3D printed microstructures under mild conditions. Three bifunctional silane crosslinkers carrying various substitutions on the silicon atom are synthesized. The photoresists are prepared by mixing these silane crosslinkers with pentaerythritol triacrylate and a two-photon photoinitiator. The presence of pentaerythritol triacrylate significantly enhances the direct laser written structures with regard to resolution, while the microstructures remain cleavable. For the targeted cleavage of the fabricated 3D microstructures, simply a methanol solution including inorganic salts is required, highlighting the mild cleavage conditions. Critically, the photoresists can be cleaved selectively, which enables the sequential degradation of direct laser written structures and allows for subtractive manufacturing at the micro- and nanoscale.

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“…The pH of bicarbonate buffer and the exposure time of a hydrogel to the acidic buffer were tuned to emulate a condition to implant a drug-encapsulated hydrogel into inflammatory or pathologic tissue which is known to present acidic pH. 11,33 As expected, in the acidic medium, the swelling ratio of the hydrogel was decreased over time (Supplemental Figure 5). The quantified deswelling rate (K d ) calculated from the first-order kinetics (eqn ( 4)) was exponentially decreased with F M and M w of the crosslinker (Fig.…”

Section: Analysis Of Ph Responsiveness and Structural Integrity Of Th...mentioning

confidence: 87%

“…[6][7][8][9][10] For example, tumor and inflammatory tissues present an acidic environment relative to normal tissue, requiring a gel that releases drug molecules in response to pH change. 11,12 The successful use of the hydrogels in these applications greatly relies on the rate and degree of volumetric changes the hydrogels have in response to an external stimulus and also the gel's ability to maintain structural integrity throughout the repetitive deformation.…”

Section: Introductionmentioning

confidence: 99%

Tuning responsiveness and structural integrity of a pH responsive hydrogel using a poly(ethylene glycol) cross-linker

Jeong¹,

Schmidt²,

Cha³

et al. 2010

Soft Matter

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Stimulus responsive hydrogels have received considerable attention due to their ability to exhibit reversible volumetric changes in response to external stimuli. The shrinkage or expansion of a hydrogel often results in irreversible structural failure, but limited efforts have been made to resolve the challenge of hydrogel fracture. This study presents that the number (F M ) of cross-linkers and the molecular weight (M w ) of the cross-linkers play critical roles determining the responsiveness and the structural integrity of a hydrogel exposed to external stimuli. A pH-responsive hydrogel was prepared by crosslinking poly(acrylamide-co-acrylic acid) with bis-acrylamide (Bis) or poly(ethylene glycol) diacrylate (PEGDA) of varying M w . The deswelling rate of the hydrogel incubated in an acidic medium was solely controlled by the number of elastically effective cross-links (N) which was increased with F M and M w of the cross-linker. The structural integrity of the hydrogel during a volumetric change was dependent on the work to fracture and the deswelling rate, which was tuned with the M w of the cross-linker. These critical roles of cross-linkers in mediating the elastic response and the structural integrity of the hydrogel were further related to the ability of cross-linkers of different M w to self-organize. Ultimately, the results of this study will be highly useful to tuning performance of a wide array of stimulus responsive hydrogels.

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Tuning hydrogel properties and function using substituent effects

Cited by 13 publications

References 16 publications

Chitosan-PEG Hydrogel with Sol-Gel Transition Triggerable by Multiple External Stimuli

Chitosan-PEG Hydrogel with Sol-Gel Transition Triggerable by Multiple External Stimuli

Adding chemically selective subtraction to multi-material 3D additive manufacturing

Tuning responsiveness and structural integrity of a pH responsive hydrogel using a poly(ethylene glycol) cross-linker

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