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. 2023 Oct 31;16(21):6985.
doi: 10.3390/ma16216985.

Process Development of a Generative Method for Partial and Controlled Integration of Active Substances into Open-Porous Matrix Structures

Lena Burger  1   2 , Achim Conzelmann  1   2 , Sven Ulrich  1   2 , Hadi Mozaffari-Jovein  1   3
Affiliations

Process Development of a Generative Method for Partial and Controlled Integration of Active Substances into Open-Porous Matrix Structures

Lena Burger et al. Materials (Basel). .

Abstract

A special generative manufacturing (AM) process was developed for the partial integration of active ingredients into open-porous matrix structures. A mixture of a silver-containing solution as an antibacterial material with an alginate hydrogel as a carrier system was produced as the active ingredient. The AM process developed was used to introduce the active ingredient solution into an open-porous niobium containing a β-titanium matrix structure, thus creating a reproducible active ingredient delivery system. The matrix structure had already been produced in a separate AM process by means of selective laser melting (SLM). The main advantage of this process is the ability to control porosity with high precision. To determine optimal surface conditions for the integration of active ingredients into the matrix structure, different surface conditions of the titanium substrate were tested for their impact on wetting behaviour of a silver-containing hydrogel solution. The solution-substrate contact angle was measured and evaluated to determine the most favourable surface condition. To develop the generative manufacturing process, an FDM printer underwent modifications that permitted partial application of the drug solution to the structure in accordance with the bioprinting principle. The modified process enabled flexible control and programming of both the position and volume of the applied drug. Furthermore, the process was able to fill up to 95% of the titanium matrix body pore volume used. The customised application of drug carriers onto implants as a drug delivery system can be achieved via the developed process, providing an alternative to established methods like dip coating that lack this capability.

Keywords: additive manufacturing; antibacterial agents; bioprinting; contact angle; drug delivery system; hydrogel; porous matrix; surface functionalisation; titanium matrix.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Dimensions of the BCC open-porous structures and their desired values.
Figure 2
Figure 2
(a) Model used for the fabrication of the cubic space-centred unit cell; (b) top surface of a BCC matrix fabricated by SLM.
Figure 3
Figure 3
Structure of the printed holder with Luer lock connection, (a) sectional drawing of the nozzle holder, and (b) assembled state.
Figure 4
Figure 4
Sequence of the filling process over the top surface of the BCC structure.
Figure 5
Figure 5
Surface conditions of the additive manufactured titanium-based alloy (a) as-built (500×); (b) ground (500×); (c) ground and polished (500×).
Figure 6
Figure 6
State 1 of the 2 wt.% alginate solution on the (a) as-built surface, (b) the ground surface and (c) the polished surface.
Figure 7
Figure 7
Change in contact angle between states 1 and 3 depending on surface condition.
Figure 8
Figure 8
Structure filling and initial structure density for the functionalisation tests.
Figure 9
Figure 9
Light microscope image of the functionalised surface (20×) and detailed image of the elementary cells (50×).
See this image and copyright information in PMC

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