3D printing hybrid organometallic polymer‐based biomaterials via laser two‐photon polymerization

Abstract

Materials with microscale structures are gaining increasing interest due to their range of technical and medical applications. Additive manufacturing approaches to such objects via laser two‐photon polymerization, also known as multiphoton fabrication, enable the creation of new materials with diverse and tunable properties. Here, we investigate the properties of 3D structures composed of organometallic polymers incorporating aluminium, titanium, vanadium and zirconium. The organometallic polymer‐based materials were analysed using a variety of techniques including SEM, energy‐dispersive X‐ray spectroscopy, X‐ray photoelectron spectroscopy analysis and contact angle measurements and their biocompatibility was tested in vitro. Cell viability and mode of death were determined by 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2H‐tetrazolium bromide (MTT) assay and acridine orange/ethidium bromide staining. Polymers incorporating Al, Ti and Zr supported cell adhesion and proliferation, and showed low toxicity in vitro, whereas the organometallic polymer incorporating V was shown to be cytotoxic. Inductively coupled plasma optical emission spectrometry suggested that leaching of the V from the organometallic polymer is the likely cause of this. The preparation of the organometallic polymers is straightforward and both simple 2D and complex 3D structures can be fabricated with ease. Resolution tests of the newly developed organometallic polymer incorporating Al show that suspended lines with widths down to 200 nm can be fabricated. We believe that the materials described in this work show promising properties for the development of objects with sub‐micron features for biomedical applications (e.g. biosensors, drug delivery devices, tissue scaffolds etc.). © 2019 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Biocompatibility Investigation of Hybrid Organometallic Polymers for Sub-Micron 3D Printing via Laser Two-Photon Polymerisation

“…As mentioned in the introduction and methods, the possibility of structuring the Al-based hybrid material has already been described previously [21]. However, we wanted to further demonstrate our ability to fabricate complex 3D shapes and thus have fabricated a micro-structure reminiscent of Zerg (StarCraft, Blizzard Entertainment © , Irvine, CA, USA)—see Figure 1.…”

“…In our previous work [21], we investigated the contact angles of these materials and found them to be 39° for Glass, 72° for Al-based hybrid materials and 71° for Zr-based hybrid materials. The collagen adsorption data does not seem to correlate with the surface contact angles.…”

“…The hybrid organometallic polymers were synthesised according to published protocols [21,25] Briefly, the Al-based material was prepared by dissolution of aluminium isopropoxide (AIP, ≥98%, Merck, Kenilworth, NJ, USA) in toluene (ACS, ISO, Reag. Ph Eur, Merck, Kenilworth, NJ, USA).…”

“…A group of interesting materials for LTPP are hybrid organometallic polymers [20]. To date, materials based on Al [21], Ge [22], Ti [23], V [24] and Zr [25] have been shown to be structurable using LTPP systems. An in vitro biocompatibility screening study showed that Al and Ti hybrids supported a comparable number of cells to glass, while the Zr-based hybrid exceeded the biocompatibility of all the other surfaces [21].…”

“…To date, materials based on Al [21], Ge [22], Ti [23], V [24] and Zr [25] have been shown to be structurable using LTPP systems. An in vitro biocompatibility screening study showed that Al and Ti hybrids supported a comparable number of cells to glass, while the Zr-based hybrid exceeded the biocompatibility of all the other surfaces [21]. An in vivo study of our Zr-based hybrids showed them to be relatively biocompatible when implanted in rabbit muscle and that they did not cause inflammation or foreign body reaction as demonstrated by hematoxylin and eosin staining [26].…”