Abstract
Upconversion nanoparticles (UCNPs) are suitable materials for bioapplications due to their ability to emit visible light under near infrared (NIR) excitation, in the biological transparency range. Polycaprolactone(PCL)-based scaffolds are widely used in tissue engineering in combination with inorganic compounds to improve bioactivity and osteoconductive properties. This work proposes a 3D printed composite scaffold with upconversion property aiming at biomedical applications in therapy-stimulated bone repair and photodynamic therapy (PDT). The system combines PCL polymer, UCNPs-apatite and a PDT photosensitizer. Thermal and rheological behaviors of the composite were similar to pure PCL polymer. Mechanical properties were improved by adding UCNPs-apatite. The 3D printable composite presented upconversion property and potential for PDT application, which was demonstrated by singlet oxygen generation under 980 nm excitation. Cytotoxicity, genotoxicity and mutagenicity assays indicated no toxicological effects at low concentrations of rare earth elements. Taken together, a potential multifunctional material is proposed for biomedical applications.
Highlights
Lanthanide (Ln3+)-doped upconversion nanoparticles (UCNPs) have emerged as an attractive luminescent material due to their excellent optical properties related to their ability to convert low-energy near-infrared (NIR) light into high-energy UV or visible light in a process that involves the sequential absorption of photons.[1]
For UCNPs-apatite, such bands appear on the shoulders at 941, 968, 852 and 842 cm‐1.52 The UCNPs-apatite presents the characteristic bands of both apatite and UNCPs, suggesting no alteration of these phases during the synthesis
A polymer (PCL) was added, and a composite PCL/UCNPs-apatite was obtained by an extrusion process. 3D-printed scaffolds using PCL/UCNPs-apatite filaments were manufactured by fused filament fabrication (FFF) technology
Summary
Lanthanide (Ln3+)-doped upconversion nanoparticles (UCNPs) have emerged as an attractive luminescent material due to their excellent optical properties related to their ability to convert low-energy near-infrared (NIR) light into high-energy UV or visible light in a process that involves the sequential absorption of photons.[1]. Negative controls (NC) were wells with culture medium supplemented with 10% FBS in the absence of any eluate, while positive controls (PC) were treated with hydrogen peroxide (80 μmol L-1 for 10 min) (all experiments were carried out in duplicate). Negative controls (NC) were culture flasks with culture medium supplemented with 10% FBS in the absence of any eluate (untreated controls), while positive controls (PC) were treated with doxorubicin hydrochloride (0.15 μg mL-1) for 4 h. PDT assays The PCL/UCNPs-apatite composite was prepared containing the photosensitizer (PS) erythrosine B to study the capability of this material to generate singlet oxygen under near-infrared irradiation. The measurements were performed in D2O to increase the 1O2 lifetime and under air-equilibrated conditions
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