Photopolymerization of biomaterials: issues and potentialities in drug delivery, tissue engineering, and cell encapsulation applications

Abstract

Photopolymerization is a widely explored technology that has recently been recognized to have also great potentialities in the biomedical field. This paper aims to provide a general overview of this technology by briefly describing materials and methods used to produce linear or crosslinked polymer networks for drug delivery, tissue engineering and cell encapsulation. In addition, potentialities and areas of investigation that are not fully explored but that could provide solutions for better control over the technology when applied to the biomedical field will be indicated as well.  2006 Society of Chemical Industry Keywords: photopolymerization; drug delivery; tissue engineering; cell encapsulation OVERVIEW OF PHOTOPOLYMERS AND THEIR USEFULNESS IN BIOMATERIAL APPLICATIONPhotopolymerization is a technique that uses light to initiate and propagate a polymerization reaction to form a linear or crosslinked polymer structure. This technology has been widely explored in optoelectronics (e.g. videodisc coatings, photolithographic resists, aspherical lens production), non-linear optics (e.g. optical fiber communication, photonic integrated circuits, holographic data storage), the coating industry, the paint and printing ink industries, in adhesives, in composite materials, in the production of high resolution images (e.g. printing plates, optical discs, microcircuits), in three-dimensional stereolithography, in holographic recordings and in the food industry.1 Recently, the use of photopolymerization has been also proposed for the production of biomaterial-based polymer networks that could be differently fabricated for specific biomedical applications. The interest beyond these applications is due to a combination of properties held by photopolymerizable precursors and/or photopolymerized polymer networks. Some of the most important attributes are: ease in production and implantation; possibility of carrying out photopolymerization in vivo or ex vivo, which respectively allow for production-and-implantation via minimal invasive surgery, and for fabrication of complex shaped polymeric matrices; in several cases, spatial and temporal control of the polymerization process; versatility of formulation and application; possibility of entrapping a wide range of substances and cells; formulation ingredients can be stored in the most appropriate conditions until use, when they have to be mixed together before production of polymer networks.Consequently, scientists have suggested the utilization of photopolymerized polymer networks in drug delivery, 2 -13 tissue engineering, 14 -34 cell encapsulation, 35 -55 and as tissue barriers, 56 -60 fillers, 61,62 biomimetic coatings and materials, 1,63 -65 adsorption membranes, 1,66 contact lenses, 1 and dental restorative materials (e.g. dental composites, pit and fissure sealants, dentine bonding agents and cements, dental adhesives, denture and elastomeric impression materials), 1,67 -69 and for the production of microfluidic devices, nanodevices and nano-patterne...

Hydrogels for Tissue Engineering and Delivery of Tissue-Inducing Substances

“…[7][8][9][10][11][13][14][15][31][32][33][34][35][36][37] In this manuscript, preparation methods are grouped into those for production of chemical gels and those for production of physical gels, and are resumed in Table 1.…”

“…In addition, thermosensitive or photopolymerizable HG-forming polymer networks may be located in the body through minimal invasive surgery, and transformed in HGs in ''in vivo'' conditions, [9][10][11] increasing patient compliance and avoiding other preparation methods that could be too aggressive when designing a structure that could serve as a tissue support and as a delivery system for tissueinducing substances (the majority are proteins).…”

Vinyl carbonate photopolymers with improved mechanical properties for biomedical applications

“…(meth)acrylate groups. [29,30] However, toxicity issues [26,27] of (meth) acrylates are present also for these materials. In addition, upon degradation poly[(meth)acrylic acid] is among the degradation products, [31,32] which, in combination with the predominant autocatalytic bulk erosion mechanism of the biopolymer, [33,34] constitute large amounts of free acid of high Mw that can lead to inflammatory response and ultimately fracture due to implant failure.…”

Insight into hydrogels

“…On the other hand, for the preparations of physically crosslinked hydrogels, several techniques have been implied such as hydrogen bonding, [37,38] crystallization, [39] protein interaction, [40] ionic interaction, [41][42][43] and by hydrophobic interaction. [44,45] Stimuli responsive hydrogels are nowadays gaining a wide interest in the field of drug delivery system and have numerous potential applications.…”