Bisphosphonate-incorporated coatings for orthopedic implants functionalization.

Bisphosphonates (BPs), the stable analogs of pyrophosphate, are well-known inhibitors of osteoclastogenesis to prevent osteoporotic bone loss and improve implant osseointegration in patients suffering from osteoporosis. Compared to systemic administration, BPs-incorporated coatings enable the direct delivery of BPs to the local area, which will precisely enhance osseointegration and bone repair without the systemic side effects. However, an elaborate and comprehensive review of BP coatings of implants is lacking. Herein, the cellular level (e.g., osteoclasts, osteocytes, osteoblasts, osteoclast precursors, and bone mesenchymal stem cells) and molecular biological regulatory mechanism of BPs in regulating bone homeostasis are overviewed systematically. Moreover, the currently available methods (e.g., chemical reaction, porous carriers, and organic material films) of BP coatings construction are outlined and summarized in detail. As one of the key directions, the latest advances of BP-coated implants to enhance bone repair and osseointegration in basic experiments and clinical trials are presented and critically evaluated. Finally, the challenges and prospects of BP coatings are also purposed, and it will open a new chapter in clinical translation for BP-coated implants.

Novel Design of the Compound Sleeve and Stem Prosthesis for Treatment of Proximal Femur Bone Defects Based on Topology Optimization.

The loosening of traditional prosthetics is among the leading causes of surgical failure of proximal femoral bone defects. A novel compound sleeve and stem prosthesis was designed using an optimization methodology that combined an octet-truss porous structure with density-based topology optimization to improve stability, promote bone ingrowth, and enhance biomechanical properties. Biomechanical changes were assessed using finite element analysis. The distribution of stress, the strain energy density, and the relative micromotion in the optimized group were considered. The optimized sleeve prosthesis achieved a 31.5% weight reduction. The maximum stresses in the optimized group were observed to decrease by 30.33 and 4.74% at the back sleeve and neck part of stem prosthesis, with a 29.52% increase in the femur, respectively. The average stress in most selected regions in the optimized group was significantly greater than that in the original group (p < 0.05). The maximum relative micromotion decreased by 15.18% (from 63.9 to 54.2 µm) in the optimized group. The novel designed compound sleeve and stem prosthesis could effectively improve the biomechanical performance of next-generation prosthetics and provide a microenvironment for bone ingrowth. The presented method could serve as a model for clinical practice and a platform for future orthopedic surgery applications.

Improving the Stability of a Hemipelvic Prosthesis Based on Bone Mineral Density Screw Channel and Prosthesis Optimization Design.

In pelvic reconstruction surgery, the hemipelvic prosthesis can cause significant changes in stress distribution due to its high stiffness, and its solid structure is not suitable for osseointegration. The purpose of this study was to identify a novel bone mineral density screw channel and design the structure of the prosthesis so as to improve the distribution of stress, promote bone growth, and enhance the biomechanical properties of the prosthesis. The mechanical characteristics of bone mineral density screw and traditional screw were compared by finite element analysis method, and redesigned by topology optimization. The direction of the newly proposed screw channel was the posterolateral entrance of the auricular surface, ending at the contralateral sacral cape. Compared to the original group, the maximum stress of the optimized prosthesis was decreased by 24.39%, the maximum stress of the sacrum in the optimized group was decreased by 27.23%, and the average strain energy density of the sacrum in the optimized group was increased by 8.43%. On the surface of screw and connecting plate, the area with micromotion more than 28 µm is reduced by 12.17%. On the screw surface, the area with micromotion more than 28 µm is reduced by 22.9%. The newly determined screw channel and optimized prosthesis design can effectively improve the biomechanical properties of a prosthesis and the microenvironment of osseointegration. This method can provide a reference for the fixation of prostheses in clinical pelvic reconstruction.

Cyclen-functionalized perylenebisimides as sensitive and selective fluorescent sensors for Pb2+ in aqueous solution.

Cyclen-functionalized perylenediimides PBI-1 and PBI-2 were first synthesized as highly sensitive and selective fluorescent chemosensors for Pb(2+) in aqueous solution. PBI-2 shows a better selectivity for Pb(2+) in the presence of other metal ions and, importantly, it can successfully enter the cell and be applied in imaging of living cells.