Two-photon polymerization of polyethylene glycol diacrylate scaffolds with riboflavin and triethanolamine used as a water-soluble photoinitiator.

Aim: In this study, the suitability of a mixture containing riboflavin (vitamin B2) and triethanolamine (TEOHA) as a novel biocompatible photoinitiator for two-photon polymerization (2PP) processing was investigated.

Materials & Methods: Polyethylene glycol diacrylate was crosslinked using Irgacure(®) 369, Irgacure 2959 or a riboflavin-TEOHA mixture; biocompatibility of the photopolymer extract solutions was subsequently assessed via endothelial cell proliferation assay, endothelial cell viability assay and single-cell gel electrophoresis (comet) assay. Use of a riboflavin-TEOHA mixture as a photoinitiator for 2PP processing of a tissue engineering scaffold and subsequent seeding of this scaffold with GM-7373 bovine aortic endothelial cells was also demonstrated.

The Effects of Geometry on Skin Penetration and Failure of Polymer Microneedles.

Microneedles are small-scale devices that may be used for drug delivery and biosensing. In this study, the forces required for mechanical failure, the modes of mechanical failure, as well as the mechanisms for microneedle penetration into porcine skin were examined. Microneedles produced from the acrylate-based polymer e-Shell 200 using an indirect rapid prototyping approach involving two-photon polymerization and poly(dimethylsiloxane) micromolding were found to possess sufficient strength for penetration of porcine skin.

Two-photon polymerization microstructuring in regenerative medicine.

Two-photon polymerization has developed as a powerful tool for making micro- and nanoscale structures for regenerative medicine applications. This review discusses micro- and nanoscale aspects of tissue engineering, which are followed by a brief description of the two-photon polymerization process and how it has been used thus far in tissue engineering and other regenerative medicine applications. Lastly, potential future applications of two-photon polymerization in regenerative medicine are presented.

Fabrication of fibrin scaffolds with controlled microscale architecture by a two-photon polymerization-micromolding technique.

Fabrication of three-dimensional (3D) fibrin scaffolds with tightly controllable pore sizes and interconnections has been investigated. The scaffolds were produced using a combination of two-photon polymerization (2PP) and micromolding techniques. Master structures were fabricated by 2PP and regenerated in fibrin by a two-step microreplication procedure.

Fabrication of microscale medical devices by two-photon polymerization with multiple foci via a spatial light modulator.

Two-photon polymerization is an appealing technique for producing microscale devices due to its flexibility in producing structures with a wide range of geometries as well as its compatibility with materials suitable for biomedical applications. The greatest limiting factor in widespread use of two-photon polymerization is the slow fabrication times associated with line-by-line, high-resolution structuring. In this study, a recently developed technology was used to produce microstructures by two-photon polymerization with multiple foci, which significantly reduces the production time.

Integrated carbon fiber electrodes within hollow polymer microneedles for transdermal electrochemical sensing.

In this study, carbon fiber electrodes were incorporated within a hollow microneedle array, which was fabricated using a digital micromirror device-based stereolithography instrument. Cell proliferation on the acrylate-based polymer used in microneedle fabrication was examined with human dermal fibroblasts and neonatal human epidermal keratinocytes. Studies involving full-thickness cadaveric porcine skin and trypan blue dye demonstrated that the hollow microneedles remained intact after puncturing the outermost layer of cadaveric porcine skin.

Multiphoton microscopy of transdermal quantum dot delivery using two photon polymerization-fabricated polymer microneedles.

Due to their ability to serve as fluorophores and drug delivery vehicles, quantum dots are a powerful tool for theranostics-based clinical applications. In this study, microneedle devices for transdermal drug delivery were fabricated by means of two-photon polymerization of an acrylate-based polymer. We examined proliferation of cells on this polymer using neonatal human epidermal keratinocytes and human dermal fibroblasts.

Fabrication of microneedles using two photon polymerization for transdermal delivery of nanomaterials.

Microneedle devices for transdermal delivery of nanoscale pharmacologic agents were fabricated out of organically-modified ceramic (Ormocer) materials using two photon polymerization. Out-of-plane hollow microneedle arrays with various aspect ratios were fabricated using this rapid prototyping process. Human epidermal keratinocyte (HEK) viability on Ormocer surfaces fabricated using two photon polymerization was similar to that on control surfaces.

Two Photon Polymerization-Micromolding of Polyethylene Glycol-Gentamicin Sulfate Microneedles.

The use of microneedles for transdermal drug delivery is limited due to the risk of infection associated with formation of channels through the stratum corneum layer of the epidermis. The risk of infection associated with use of microneedles may be reduced by imparting these devices with antimicrobial properties. In this study, a photopolymerization-micromolding technique was used to fabricate microneedle arrays from a photosensitive material containing polyethylene glycol 600 diacrylate, gentamicin sulfate, and a photoinitiator.

Laser direct writing of micro- and nano-scale medical devices.

Laser-based direct writing of materials has undergone significant development in recent years. The ability to modify a variety of materials at small length scales and using short production times provides laser direct writing with unique capabilities for fabrication of medical devices. In many laser-based rapid prototyping methods, microscale and submicroscale structuring of materials is controlled by computer-generated models.

Two-photon polymerization of microneedles for transdermal drug delivery.

Importance Of The Field: Microneedles are small-scale devices that are finding use for transdermal delivery of protein-based pharmacologic agents and nucleic acid-based pharmacologic agents; however, microneedles prepared using conventional microelectronics-based technologies have several shortcomings, which have limited translation of these devices into widespread clinical use.

Areas Covered In This Review: Two-photon polymerization is a laser-based rapid prototyping technique that has been used recently for direct fabrication of hollow microneedles with a wide variety of geometries. In addition, an indirect rapid prototyping method that involves two-photon polymerization and polydimethyl siloxane micromolding has been used for fabrication of solid microneedles with exceptional mechanical properties.

In situ collagen polymerization of layered cell-seeded electrospun scaffolds for bone tissue engineering applications.

Electrospun scaffolds have been studied extensively for their potential use in bone tissue engineering applications. However, inherent issues with the electrospinning approach limit the thickness of these scaffolds and constrain their use for repair of critical-sized bone defects. One method to increase overall scaffold thickness is to bond multiple electrospun scaffolds together with a biocompatible gel.

Fabrication of polymer microneedles using a two-photon polymerization and micromolding process.

Background: Microneedle-mediated drug delivery is a promising method for transdermal delivery of insulin, incretin mimetics, and other protein-based pharmacologic agents for treatment of diabetes mellitus. One factor that has limited clinical application of conventional microneedle technology is the poor fracture behavior of microneedles that are created using conventional materials and methods. In this study polymer microneedles for transdermal delivery were created using a two-photon polymerization (2PP) microfabrication and subsequent polydimethylsiloxane (PDMS) micromolding process.

Supercapacitive transport of pharmacologic agents using nanoporous gold electrodes.

In this study, nanoporous gold supercapacitors were produced by electrochemical dealloying of gold-silver alloy. Scanning electron microscopy and energy dispersive X-ray spectroscopy confirmed completion of the dealloying process and generation of a porous gold material with approximately 10 nm diameter pores. Cyclic voltammetry and chronoamperometry of the nanoporous gold electrodes indicated that these materials exhibited supercapacitor behavior.

Rapid prototyping of scaphoid and lunate bones.

In this study, a novel rapid prototyping technology was used to fabricate scaphoid and lunate bone prostheses, two carpal bones that are prone to avascular necrosis. Carpal prostheses were fabricated with an Envisiontec Perfactory SXGA stereolithography system using Envisiontec eShell 200 photocurable polymer. Fabrication was guided using 3-D models, which were generated using Mimics software (Materialise NV, Leuven, Belgium) from patient computer tomography data.