Electrohydrodynamic jet (EHDJ) printing has emerged as a powerful technique for fabricating micro- and nanoscale fibrous scaffolds with exceptional structural precision. This study presents a novel strategy for creating high-resolution, NIR-II active polycaprolactone (PCL) scaffolds using a macromolecular fluorescent dye, SY-COO-PCL, integrated into the printing ink. The method enables real-time, noninvasive tracking of implanted scaffolds in living organisms while maintaining excellent biocompatibility and controlled degradation.
The fabrication process began with the synthesis of SY-COO-PCL by chemically grafting the small organic NIR-II dye SY-1030 onto PCL-diol (Mn ≈ 3000 Da) through an esterification reaction mediated by EDCI and DMAP. The resulting conjugate was purified and characterized via gel permeation chromatography (GPC), confirming a molecular weight increase consistent with successful dye attachment. UV-Vis-NIR absorption and fluorescence spectroscopy revealed strong NIR-II emission at 980 nm with a broad spectral profile from 850 to 1300 nm, indicating suitability for deep-tissue imaging.
PCL ink was prepared by dissolving SY-COO-PCL in glacial acetic acid at 80% w/v concentration.Phospho-RPS6 Antibody References The highly viscous solution was used in a custom-built EHDJ printer equipped with a programmable motorized stage. Grid-shaped scaffolds with 200 µm pore size and 20 layers were successfully printed under optimized conditions: voltage of 15 kV, nozzle-to-substrate distance of 2 mm, feeding rate of 1 µL/min, and stage speed of 10 mm/s. To prevent photodegradation, printing was conducted in a dark environment. Scanning electron microscopy (SEM) confirmed the formation of ultrafine fibers with average widths of 15.1 ± 0.8 µm (top) and 27.3 ± 5.9 µm (bottom), significantly finer than those produced by conventional fused deposition modeling.
The scaffolds exhibited uniform distribution of fluorescence across their structure, enabling clear visualization upon implantation. In vivo imaging was performed using a small-animal NIR-II system (excitation at 808 nm, detection at >1000 nm). Scaffolds containing SY-COO-PCL were detectable within one week post-implantation, with signal intensity remaining stable for up to three weeks.MYL1 Antibody Formula Image quality improved with higher dye concentration and optimal exposure time (400 ms), yielding high signal-to-noise ratios and spatial resolution down to 25 µm.PMID:35128209
Comparative analysis with scaffolds containing physically blended SY-1030 showed that covalent immobilization drastically reduced dye leaching and enhanced long-term stability. Fluorescence decay curves indicated that SY-COO-PCL scaffolds retained approximately 20% of their initial signal after 21 days, compared to rapid signal loss in control groups. This extended visibility is attributed to the chemical anchoring of the dye within the polymer matrix, preventing diffusion into surrounding tissues.
Moreover, the scaffolds demonstrated excellent biocompatibility during in vivo evaluation. No significant immune response or tissue necrosis was observed over a 3-month period. Histological sections revealed organized connective tissue infiltration, vascular ingrowth, and gradual degradation of scaffold fibers without foreign body reactions. SEM images at 1, 2, and 3 months showed progressive surface erosion and nanoporous structures, indicative of enzymatic hydrolysis and oxidative breakdown.
These results highlight the potential of EHDJ printing combined with macromolecular dye integration for next-generation bioactive implants. The ability to produce structurally precise, fluorescently labeled scaffolds opens new avenues for monitoring tissue regeneration dynamics, evaluating scaffold performance, and enabling feedback-controlled therapeutic interventions. With further development, this approach could be extended to other biodegradable polymers and complex 3D architectures for advanced regenerative medicine applications.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com