Abstract
Photochemical tissue bonding (PTB), based on photosensitizer rose bengal (RB) and green light, has been regarded as an effective alternative to surgical suture and has been reported to provide benefits for Achilles tendon repair. Limited to the poor penetration of green light, secondary damage still exists while applying PTB for closed Achilles tendon rupture. This study is aimed at exploring the effects of noninvasive photochemical sealing on Achilles tendon rupture by the combination of PTB and upconversion nanoparticles (UCNPs). The rare-earth UCNPs of NaYF4 : Yb/Er (Y : Yb : Er = 78 : 20 : 2) were fabricated and then loaded into Chitosan/β-GP hydrogel containing RB to prepare UCNPs@RB/Chitosan/β-GP hydrogel. The properties of UCNPs and UCNP/Chitosan/β-GP hydrogel were characterized by TEM, SEM, DLS, and FTIR analysis. The effects of UCNP and PTB combination were evaluated in an Achilles tendon rupture rat model using histological analysis. Bioluminescence imaging of ROS was performed to explore the potential mechanism. UCNPs had a uniform shape with a diameter of 29.7 ± 2.6 nm. The UCNPs@RB/Chitosan/β-GP hydrogel could upconvert the near-infrared light into green light. The results of histological assessment showed that compared with traditional suture repair, the rats injected with UCNPs@RB/Chitosan/β-GP hydrogel followed by irradiating with near-infrared light and the rats treated with RB solution followed by irradiating with green light had better effects on Achilles tendon repair. The benefits might be related to the generation of ROS in the PTB process. These findings indicated that the combination of PTB and UCNPs@RB/Chitosan/β-GP hydrogel could be used as a noninvasive photochemical sealing for Achilles tendon rupture.
Highlights
Achilles tendon rupture is widely reported, and its incidence increases every year
The addition of upconversion nanoparticles (UCNPs) did not affect the morphological structure of Chitosan/β-GP hydrogel (Figures 1(c) and 1(d))
The combination of Photochemical tissue bonding (PTB) and UCNPs@rose bengal (RB)/Chitosan/β-GP hydrogel could be used as a noninvasive photochemical sealing for Achilles tendon rupture
Summary
Achilles tendon rupture is widely reported, and its incidence increases every year. In Denmark, the incidence of acute Achilles tendon rupture increased from 26.95 per 10,000 persons per year in 1994 to 31.17 per 10,000 persons per year in 2013 [1]. Operative and nonoperative methods are broadly used for the treatment of Achilles tendon rupture. Compared with the nonoperative treatment, the operative treatment had a lower risk of rerupture [2,3,4,5]. Operative therapy increased the risk of many complications, including infection, adhesions, sural nerve injury, deep vein thrombosis, and disturbed skin sensibility [2,3,4,5]. RB could absorb the photons of green laser and generate ROS reacting with amino acids in structural proteins, in which covalent binding between proteins, including
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