Implant loading can create micromotion at the bone-implant interface. The interfacial strain associated with implant micromotion could contribute to regulating the tissue healing response. Excessive micromotion can lead to fibrous encapsulation and implant loosening. Our objective was to characterize the influence of interfacial strain on bone regeneration around implants in mouse tibiae. A micromotion system was used to create strain under conditions of (1) no initial contact between implant and bone, and (2) a direct bone-implant contact. Pin- and screw-shaped implants were subjected to displacements of 150 μm or 300 μm, 60 cycles/day, for 7 days. Pin-shaped implants placed in 5 animals were subjected to 3 sessions of 150 μm displacement per day, with 60 cycles per session. Control implants in both types of interfaces were stabilized throughout the healing period. Experimental strain analyses, microtomography, image-based displacement mapping, and finite element simulations were used to characterize interfacial strain fields. Calcified tissue sections were prepared and stained with Goldner to evaluate tissue reaction in higher and lower strain regions. In stable implants, bone formation occurred consistently around the implants. In implants subjected to micromotion, bone regeneration was disrupted in areas of high strain concentrations (e.g. > 30%), whereas lower strain values were permissive of bone formation. Increasing implant displacement or number of cycles per day also changed the strain distribution and disturbed bone healing. These results indicate that not only implant micromotion but also the associated interfacial strain field contributes to regulating the interfacial mechanobiology at healing bone-implant interfaces.

In this work, a novel near‐infrared (NIR) persistent luminescence (PersL) material Na2CaGe5SiO14 (NCGSO):Cr3+ is designed and prepared. The phase composition and crystal structure are analyzed by X‐ray diffraction (XRD) and Rietveld structural refinement. The band gap of NCGSO is calculated to be 4.245 eV by density functional theory (DFT) and confirmed by diffuse reflection spectroscopy (DRS). It is determined by the photoluminescence (PL) spectra, X‐ray absorption near‐edge spectroscopy (XANES), and time‐resolved emission spectra (TRES) that three Ge4+ sites can be superseded simultaneously when Cr3+ ions are doped. In addition, the PL, photoluminescence excitation (PLE), and PersL performance are analyzed systematically. Under the radiation of 254 nm ultraviolet (UV) lamp, the samples exhibit excellent PL and PersL performance in the range of 600–900 nm, and the optimal afterglow duration lasts for more than 10 h. According to results, a possible mechanism is proposed to explain the PersL phenomenon. In the end, a set of information encrypted digital labels is designed and biological tissue penetration experiments are performed. The results reveal the potential of NCGSO:Cr3+ for information encryption and biological imaging applications.

Computational analyses have been used to study the biomechanical microenvironment of the chondrocyte that cannot be assessed by in vitro experimental studies; yet all computational studies thus far have focused on the effect of zonal location (superficial, middle, and deep) on the mechanical microenvironment of chondrocytes. The aim of this paper was to study the effect of both zonal and radial locations on the biomechanical microenvironment of chondrocytes in inhomogeneous cartilage under unconfined stress relaxation. A biphasic multiscale approach was employed and nine chondrocytes in different locations were studied. Hyperelastic biphasic theory and depth-dependent aggregate modulus and permeability of articular cartilage were included in the models. It was found that both zonal and radial locations affected the biomechanical stresses and strains of the chondrocytes. Chondrocytes in the mid-radial location had increased volume during the early stage of the loading process. Maximum principal shear stress at the interface between the chondrocyte and the extracellular matrix (ECM) increased with depth, yet that at the ECM-pericellular matrix (PCM) interface had an inverse trend. Fluid pressure decreased with depth, while the fluid pressure difference between the top and bottom boundaries of the microscale model increased with depth. Regardless of location, fluid was exchanged between the chondrocyte, PCM, and ECM. These findings suggested that even under simple compressive loading conditions, the biomechanical microenvironment of the chondrocytes, PCM and ECM were spatially dependent. The current study provides new insight on chondrocyte biomechanics.

The brand new LLP material Ca6BaP4O17:Eu2+,Ho3+ exhibits about 0.13 cd m−2 initial LLP intensity and a 47 h afterglow.