Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Micro Injection Molding of Drug-Loaded Round Window Niche Implants for an Animal Model using 3D Printed Molds

Robert Mau
ORCID logo ,
Thomas Eickner
,
Gabór Jüttner
,
Ziwen Gao
ORCID logo ,
Chunjiang Wei
,
Nicklas Fiedler
ORCID logo ,
Volkmar Senz
ORCID logo ,
Thomas Lenarz
ORCID logo ,
Niels Grabow
,
Verena Scheper
* ORCID logo ,
Hermann Seitz
* ORCID logo
Version 1 : Received: 18 April 2023 / Approved: 19 April 2023 / Online: 19 April 2023 (03:57:41 CEST)

A peer-reviewed article of this Preprint also exists.

Mau, R.; Eickner, T.; Jüttner, G.; Gao, Z.; Wei, C.; Fiedler, N.; Senz, V.; Lenarz, T.; Grabow, N.; Scheper, V.; Seitz, H. Micro Injection Molding of Drug-Loaded Round Window Niche Implants for an Animal Model Using 3D-Printed Molds. Pharmaceutics 2023, 15, 1584. Mau, R.; Eickner, T.; Jüttner, G.; Gao, Z.; Wei, C.; Fiedler, N.; Senz, V.; Lenarz, T.; Grabow, N.; Scheper, V.; Seitz, H. Micro Injection Molding of Drug-Loaded Round Window Niche Implants for an Animal Model Using 3D-Printed Molds. Pharmaceutics 2023, 15, 1584.

Abstract

A novel approach for the long-term medical treatment of the inner ear is the diffusion of drugs through the round window membrane from a patient-individualized, drug-eluting implant, which is inserted in the middle ear. In this study, drug-loaded (10 wt% Dexamethasone) guinea pig round window niche implants (GP-RNIs, ~1.30 mm x 0.95 mm x 0.60 mm) were manufactured with high precision via micro injection molding (µIM, Tmold = 160 °C, crosslinking time of 120 s). The medical grade silicone elastomer MED-4244 (NuSil Technology LLC, Radnor, PA, USA) was used. Molds for µIM were 3D printed from a commercially available resin PlasGRAY V2 (Asiga, Alexandria, Australia, TG = 84 °C) via a high-resolution DLP process (xy-resolution of 32 µm, z-resolution of 10 µm, 3D printing time of about 6 h). Drug release, biocompatibility, and bio-efficacy of the GP-RNIs were investigated in vitro. GP-RNIs could be successfully produced. Wear of the molds due to thermal stress was observed. However, the molds are suitable for single use in the µIM process. About 10% of the drug load (8.2 ± 0.6 µg) was released after 6 weeks (medium: isotonic saline). The implants showed high biocompatibility over a time of 28 days (lowest cell viability ~80%). Moreover, we found anti-inflammatory effects over a time of 28 days in a TNF-α-reduction test. These results are promising for the development of long-term drug-releasing implants for human inner ear therapy.

Keywords

micro injection molding; 3D printing; rapid tooling; digital light processing; implant; drug delivery system; dexamethasone; anti-inflammatory; TNF-α; biocompatibility; inner ear therapy

Subject

Medicine and Pharmacology, Otolaryngology

Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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