3D printing fluorescent material with tunable optical properties

Abstract

The 3D printing of fluorescent materials could help develop, validate, and translate imaging technologies, including systems for fluorescence-guided surgery. Despite advances in 3D printing techniques for optical targets, no comprehensive method has been demonstrated for the simultaneous incorporation of fluorophores and fine-tuning of absorption and scattering properties. Here, we introduce a photopolymer-based 3D printing method for manufacturing fluorescent material with tunable optical properties. The results demonstrate the ability to 3D print various individual fluorophores at reasonably high fluorescence yields, including IR-125, quantum dots, methylene blue, and rhodamine 590. Furthermore, tuning of the absorption and reduced scattering coefficients is demonstrated within the relevant mamalian soft tissue coefficient ranges of 0.005–0.05 mm−1 and 0.2–1.5 mm−1, respectively. Fabrication of fluorophore-doped biomimicking and complex geometric structures validated the ability to print feature sizes less than 200 μm. The presented methods and optical characterization techniques provide the foundation for the manufacturing of solid 3D printed fluorescent structures, with direct relevance to biomedical optics and the broad adoption of fast manufacturing methods in fluorescence imaging.

3D-printed tissue-simulating phantoms for near-infrared fluorescence imaging of rheumatoid diseases

“…Overall, the investigations on Lumogen phantoms indicate a genuine photostability, making such phantoms well-suited for performance monitoring, device comparison, and maintenance of hand imagers. In contrast, our stability investigations on phantoms printed with ICG do not confirm the high stability over time reported by Ruiz et al 36 These authors observed deviations between þ4% and −4% (with 1% to 2% error bars) over 2 months without a systematic tendency. Possible reasons are the different base resin, the different printer types, and differences in the UV curing process.…”

“…It is well known that ICG stability is very sensitive against environmental factors. Surprisingly, Ruiz et al 35,36 explained the stability of their phantoms by differences in the chemical structure between the applied "laser dye" (IR-125) and ICG, although the data sheet of the manufacturer (Exciton Inc., Lockburne, Ohio, United States) explicitly declares that IR-125 and ICG are two names for the same substance (CAS Registry Number: 3599-32-4). 46 Our direct comparison of Lumogen and ICG phantoms illustrates that Lumogen behaves much more stable, which is in accordance with the known differences in stability between rylene and cyanine dyes.…”

“…Recently, ICG (IR-125 laser dye from Exciton Inc., Lockburne, Ohio, United States) was successfully applied as fluorophore for both conventional solid phantoms based on polyurethane, 35 and 3D-printed solid phantoms based on methacrylate resins. 36 During preparation the fluorophore was dissolved in dimethyl sulfoxide (DMSO) which is known to yield stable ICG solutions for laser emission. [37][38][39] For the polyurethane phantoms an average decrease of fluorescence intensity of about 5% within 2 months was reported, and no more change after the next 3 months.…”

3D-Printed Tumor Phantoms for Assessment of In Vivo Fluorescence Imaging Analysis Methods

“…Serial dilutions of fluorescent contrast agents can be prepared with tissue optical properties and used for system characterization; however, this method is prone to inter-user reproducibility errors, short shelf-life, and may require a dedicated preparation space to satisfy environmental hazard requirements. Solid composite phantoms provide the opportunity for extended shelf stability and multi-center distribution [ 14 , 15 ]. A solid standardization reference phantom was proposed in 2016 and has been subsequently revised in recent years [ 6 , 16 , 17 ].…”

“…This concept was extended in 2020 with a modular design to address manufacturability and utilized an ICG-equivalent fluorophore in place of quantum dots [ 14 ]. To further address design flexibility, a resin-based 3D printing technique was developed [ 15 ]. While the primary focus of many of the solid composite reference phantoms have been to provide engineers with detailed system characterization, 3D printing provides the ability to manufacture more complex shapes with controlled, homogeneous optical properties.…”