Degradable thiol-acrylate photopolymers: polymerization and degradation behavior of an in situ forming biomaterial

Rydholm, Amber E.; Bowman, Christopher N.; Anseth, Kristi S.

doi:10.1016/j.biomaterials.2004.11.046

Cited by 277 publications

(333 citation statements)

References 44 publications

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“…Thus, gels with reversible disulfide cross-links have been studied [109][110][111]. Reversible metal-ligand cross-links with a self-repairing function have also been described [112].…”

Section: Chemically Driven Gel Actuatorsmentioning

confidence: 99%

Polymer Gel Actuators: Fundamentals

Calvert

2009

Biomedical Applications of Electroactive Polymer Actuators

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One view of materials development is to search for what materials correspond to empty spaces on a hypothetical multi-dimensional map of the properties of available materials. Following a biomimetic philosophy, for instance, it can be seen that tough ceramics and moldable short fiber composites with high moduli are possible but absent from the list of available synthetic materials. Likewise artificial muscle is missing, where the properties are defined as a developed stress of over 300 kPa, a linear contraction of 25 % and a response time of below one second. Currently dielectric elastomers come closest but have disadvantages [1,2].The actin-myosin muscle system provides the performance target for electroactive polymer actuators [3,4]. The process is driven chemically by the energy change from hydrolysis of the polyphosphate bond as ATP (adenosine triphosphate) binds to myosin and is converted to ADP (adenosine diphosphate) and phosphate. A simple chemical analogy suggests that muscle-like gels should be feasible but it is now clear that the task is much harder than it seems.Early work on gel actuation by Katchalsky-Katzir demonstrated that engines could be built using the chemical energy in diluting a lithium bromide solution to drive contraction and expansion of a collagen belt [5]. In essence, the collagen expands to take up the salt solution or contract to exclude the water. This change is both a molecular conformation change and a volume change. Other chemically driven gels, for instance polyacrylic acid fibers [6] which respond to a pH change, also rely on a solubility change giving rise to a volume change.

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“…Thus, gels with reversible disulfide cross-links have been studied [109][110][111]. Reversible metal-ligand cross-links with a self-repairing function have also been described [112].…”

Section: Chemically Driven Gel Actuatorsmentioning

confidence: 99%

Polymer Gel Actuators: Fundamentals

Calvert

2009

Biomedical Applications of Electroactive Polymer Actuators

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“…Crosslinked thiol-acrylate photopolymers were made from monomer solutions containing a PLA-PEG 2000 -PLA diacrylate [41][42][43] and a monofunctional thiol (butyl-3-mercaptopropionate, Aldrich). The monomers were mixed in a 7:3 ratio of acrylate to thiol functional groups before 50 wt.% dimethyl sulfoxide and 0.1 wt.% 1--2-hydroxy-2-methyl-1-propane-1-one (Irgacure 2959, I2959, Ciba) were added, and the mixture was photopolymerized into disks 10 mm in diameter and 1 mm thick using 5 mW cm -2 of 365 nm light.…”

Section: Comparing Ester Hydrolysis At Ph 74 and Ph 80mentioning

confidence: 99%

Effects of neighboring sulfides and pH on ester hydrolysis in thiol–acrylate photopolymers

2007

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Networks synthesized through thiol-acrylate photopolymerization or Michael-type addition step growth reactions contain esters with neighboring sulfide groups. Previous work has demonstrated that these esters are readily hydrolyzable at physiological pH. Here, the influence of the distance between the sulfide and ester, as well as the water concentration, on ester hydrolysis was characterized. These preliminary results indicate that reducing the number of carbons between the sulfide and the ester from 2 to 1 increased the rate of ester hydrolysis from 0.022 ± 0.001 to 0.08 ± 0.015 days -1 . Increases in ester hydrolysis rates were also observed as hydrophilicity increased for oligomers prepared from a trithiol, tetrathiol and dithiol monomer (0.012 ± 0.003, 0.032 ± 0.004, and 0.091 ± 0.003 days -1 , respectively). Additionally, in bulk-eroding polymeric biomaterials, variations in pH impacted the ester hydrolysis rate. This work confirms that small variations in buffer pH predictably alter the mass loss profile of a thiol-acrylate photopolymer. More specifically, as buffer pH was changed from 7.4 to 8.0, the rate of ester hydrolysis increased from 0.074 ± 0.003 to 0.28 ± 0.005 days -1 . The magnitude of this observed change in ester hydrolysis rate was correlated to the increase in hydroxide ion concentration that accompanied this pH change.

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“…5 In this context, thiol-ene chemistry has many of the attributes of click chemistry and has been used to fabricate a multitude of thin-film systems [17][18][19] with outstanding efficiency and most importantly, in the presence of oxygen. More recently, the synthetic potential of thiol-ene chemistry has been exploited for the modification of the backbone of poly(oxazolines) and poly(butadiene) with an array of thiols 20 and to build glycodendrons.…”

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confidence: 99%