Synthesis and characterization of fluorescein-grafted polyurethane for potential application in biomedical tracing

Abstract

Redesigned multifunctional biopolymers represent a novel building bridge for interdisciplinary collaborations in biomaterials development. We prepared fluorescein-grafted polyurethane scaffolds (PU-C1, PU-C5, and PU-B1) to meet both clinical needs and biological safety evaluations, using different contents of calcein and different synthesis procedures for potential biomedical tracing. X-ray diffraction, infrared, X-ray photoelectron spectroscopy, nuclear magnetic resonance, scanning electron microscopy, and light microscopy were used to analyze the composition and structure of polyurethanes, as well as to observe their morphology with and without biomarkers. Fluorescence spectrophotometer and fluorescence microscopy were used to detect the fluorescence characteristics. The results showed that the grafting of calcein significantly affected the chemical structure and fluorescence sensitivities of copolymers. When compared to calcein, which was added before synthesis (PU-C1), the marker that was added during the extender process (PU-B1) presented higher fluorescence efficiency. Both PU-C5 and PU-B1 exhibited strong fluorescent response and good cytocompatibility in vitro and in vivo, with no interference from the autofluorescence of tissues after 4 weeks of implantation. The fluorescence-marked material can be used to continuously and noninvasively monitor the dynamic changes in polymers, which provides a way to clearly trace the material or to distinguish between the material and tissue in vivo.

Elastomeric Polyurethane Foams Incorporated with Nanosized Hydroxyapatite Fillers for Plastic Reconstruction

“…It is well known that there is a class of polymer materials that can be synthesized as “soft or hard scaffolds” by different segmented structures [16]. The synthetic polymer called polyurethane (PU) has been applied in tissue engineering with the advent of a wide range of mechanical and physical properties by changing the ratio of soft and hard segments and the composition [17,18]. PU exhibit diverse properties with a self-foaming porous and unique segmented structure, excellent and varying mechanical properties, and good biocompatibility, which could be considerable interest to specific tissue [19,20].…”

Biodegradable Polyurethane Scaffolds in Regeneration Therapy: Characterization and In Vivo Real-Time Degradation Monitoring by Grafted Fluorescent Tracer

“…In our previous study, a PU-based composite scaffold with castor oil and nano-hydroxyapatite prepared for bone regeneration, but the increased cross-linking density of the PU network inhibited the degradation even if the implantation was operated into rabbits for 24 weeks . Recently, a series of undegradable PU has been investigated in which different synthesis procedures have affected the fluorescence efficiency apparently . Also, CPU-5 prepared by chemical grafting with calcein (the molar ratio of calcein/soft-segment of 0.5%) as chain extender has excellent fluorescence stability and biocompatibility .…”

“…23 Pristine calcein and CPU-5 have similar fluorescence intensities, both around 2000. 23 It was surprising that the intensity of the emission of PU-5 was dramatically higher than the same concentration of pristine calcein solution (3×) and CPU-5 (3×), and the emission maximum of PU-5 presented a hypsochromic shift (Figure 1C). Hu et al found that chemical grafting of fluorescent molecules (aminofluorescein) into the PU backbone would result in a hypsochromic shift of the emission wavelength of the fluorescent PU due to an increase in the polarity of the fluorescent molecule.…”

“…PU-P did not display any fluorescent behavior under a 400 nm excitation wavelength, while PU-5 showed a bright green fluorescent response similar to that of CPU-5 in a transparent porous matrix. 23 The surface and interior of PUs were distributed with abundant micropores and an interconnected open-pore microstructure (Figure 1C and Figure S1). In the fluorescence emission spectra, the maximum emission wavelength of PU-5 and calcein appeared at 437 and 445 nm under a 400 nm excitation wavelength in THF, respectively.…”

Biological Effects, Applications and Design Strategies of Medical Polyurethanes Modified by Nanomaterials

“…150,[177][178][179] PU nanofibers prepared by electrostatic spinning mimic the reticular structure of the ECM; the addition of conductive NMs (eg MWCNTs, GO, and Au-NPs) increases the jet charge density of the preparation, reducing the PU nanofiber diameter and increasing the porosity, and provides an electrophysiological environment for directional cell attachment, migration, and proliferation. 78,[180][181][182][183]…”