Multiple modulus silicone elastomers using 3D extrusion printing of low viscosity inks

Zheng, Sijia; Zlatin, Michael; Selvaganapathy, P. Ravi; Brook, Michael A.

doi:10.1016/j.addma.2018.09.011

Cited by 42 publications

(52 citation statements)

References 18 publications

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“…This type of polymer is commonly a simple mixture of the two compounds although it is possible to integrate the photoinitiator into the polymer itself. 8 Popular reactive moieties include epoxy, 9 thiol-ene, [10][11][12] and acrylate chemistries and are matched with a compatible photoinitiator chemistry. For example, SU-8 is a popular biocompatible polymer designed for the microelectronics industry but has found uses in biomedical research; this polymer uses epoxy ring-opening chemistries combined with a photoacid generator.…”

Section: A)mentioning

confidence: 99%

Toxicity and photosensitizing assessment of gelatin methacryloyl-based hydrogels photoinitiated with lithium phenyl-2,4,6-trimethylbenzoylphosphinate in human primary renal proximal tubule epithelial cells

et al. 2019

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Gelatin methacryloyl (GelMA) and lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) photoinitiator are commonly used in combination to produce a photosensitive polymer but there are concerns that must be addressed: the presence of unreacted monomer is well known to be cytotoxic, and lithium salts are known to cause acute kidney injury. In this study, acellular 10% GelMA hydrogels cross-linked with different LAP concentrations and cross-linking illumination times were evaluated for their cytotoxicity, photosensitizing potential, and elastic moduli. Alamar Blue and CyQuant Direct Cell viability assays were performed on human primary renal proximal tubule epithelial cells (hRPTECs) exposed to extracts of each formulation. UV exposure during cross-linking was not found to affect extract cytotoxicity in either assay. LAP concentration did not affect extract cytotoxicity as determined by the Alamar Blue assay but reduced hRPTEC viability in the CyQuant Direct cell assay. Photocatalytic activity of formulation extracts toward NADH oxidation was used as a screening method for photosensitizing potential; longer UV exposure durations yielded extracts with less photocatalytic activity. Finally, elastic moduli determined using nanoindentation was found to plateau to approximately 20-25 kPa after exposure to 342 mJ/cm 2 at 2.87 mW of UV-A exposure regardless of LAP concentration. LAP at concentrations commonly used in bioprinting (<0.5% w/w) was not found to be cytotoxic although the differences in cytotoxicity evaluation determined from the two viability assays imply cell membrane damage and should be investigated further. Complete cross-linking of all formulations decreased photocatalytic activity while maintaining predictable final elastic moduli.

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Section: A)mentioning

confidence: 99%

Toxicity and photosensitizing assessment of gelatin methacryloyl-based hydrogels photoinitiated with lithium phenyl-2,4,6-trimethylbenzoylphosphinate in human primary renal proximal tubule epithelial cells

et al. 2019

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“…The fast rate of cure causes a rapid increase in viscosity during mixing of the reagents such that the needs for high viscosity starting materials and/or high‐pressure pumps used in traditional extrusion processes are obviated. [ 23 ] As a model system, we loaded a dual‐barrel syringe with either 5% mol pendent‐aminopropylsilicone and glutaraldehyde, or 3000 g mol −1 telechelic aminopropylsilicone with formaldehyde ( Figure A). Simple hand dispensing from the syringe allowed a layer‐by‐layer deposition of either material (3 × 1 mm layers → 3 mm thick letters, Figure 5B, see also a video in Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Catalyst Free Silicone Sealants That Cure Underwater

Bui

Brook

2020

Adv Funct Materials

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Silicone sealants and adhesives are widely used to prevent the ingress of water. However, silicones must normally be cured in air, as excess water inhibits or prevents cure from occurring. It is reported that aqueous solutions of the aliphatic aldehydes glutaraldehyde, glyoxal or, particularly, formaldehyde rapidly react without catalysts with a variety of aminopropyl‐modified silicone polymers to give silicone elastomers, even underwater. These products, whose properties are readily tailored by controlling the density of amino groups in the starting materials, may be 3D printed, or used both as adhesives and sealants in air or water.

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“…Silicone elastomers have been advantageously used in many applications because of the ease of fabrication, transparency, and the inherent flexibility given by the silicone elastomeric network. They may be prepared in flat sheets, as described here, but also in much more complex forms, including via 3D printing . The DPPH elastomer here constitutes an example of a responsive polymer, which are of increasing value in a wide variety of (bio)analytical assays, including microfluidic technologies that are used to measure antioxidant activity of target molecules .…”

Section: Discussionmentioning

confidence: 99%

Purple to Yellow Silicone Elastomers: Design of a Versatile Sensor for Screening Antioxidant Activity

Ogliani

Skov

Brook

2019

Adv Materials Technologies

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Antioxidants play a key role in counteracting the adverse effects of oxidative stress in human organisms. Thus, there is a huge demand for the development of smart and convenient assays for the evaluation of antioxidant activity of synthetic and natural compounds, food samples, plant extracts, etc. The design of a solid-state, flexible, and portable format of the traditional in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical test is reported. For the first time, purple DPPH radicals are physically immobilized into a silicone matrix by means of a facile and rapid process. The working principle of the resulting sensor is based on the colorimetric process that is associated with the redox reaction of DPPH radicals with antioxidants. When an antioxidant reacts with the sensor, a color change from purple to yellow can be perceived by the naked eye. The response of the sensor is investigated qualitatively and quantitatively toward food samples and selected antioxidants of different natures, and solubilized in different media. It is demonstrated that the DPPH silicone sensor is highly versatile and can be used as a ready-to-use sensor for direct colorimetric detection of antioxidants.

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Multiple modulus silicone elastomers using 3D extrusion printing of low viscosity inks

Cited by 42 publications

References 18 publications

Toxicity and photosensitizing assessment of gelatin methacryloyl-based hydrogels photoinitiated with lithium phenyl-2,4,6-trimethylbenzoylphosphinate in human primary renal proximal tubule epithelial cells

Toxicity and photosensitizing assessment of gelatin methacryloyl-based hydrogels photoinitiated with lithium phenyl-2,4,6-trimethylbenzoylphosphinate in human primary renal proximal tubule epithelial cells

Catalyst Free Silicone Sealants That Cure Underwater

Purple to Yellow Silicone Elastomers: Design of a Versatile Sensor for Screening Antioxidant Activity

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