Atomically Precise Design of PtSn Catalyst for the Understanding of the Role of Sn in Propane Dehydrogenation

Propane dehydrogenation(PDH),an atom-economic reaction to produce high-value-added propylene and hydrogen with high efficiency,has recently attracted extensive attention.The severe deactivation of Pt-based catalysts through sintering and coking remains a major challenge in this high-temperature reaction.The introduction of Sn as a promoter has been widely applied to improve the stability and selectivity of the catalysts.However,the selectivity and stability of PtSn catalysts have been found to vary considerably with synthesis methods,and the role of Sn is still far from fully understanding.To gain in-depth insights into this issue,we synthesized a series of PtSn/SiO_(2)and SnPt/SiO_(2)catalysts by varying the deposition sequence and Pt:Sn ratios using atomic layer deposition with precise control.We found that PtSn/SiO_(2)catalysts fabricated by the deposition of SnO_(x)first and then Pt,exhibited much better propylene selectivity and stability than the SnPt/SiO_(2)catalysts synthesized the other way around.We demonstrate that the presence of Sn species at the Pt-SiO_(2)interface is of essential importance for not only the stabilization of PtSn clusters against sintering under reaction conditions but also the promotion of charge transfers to Pt for high selectivity.Besides the above,the precise regulation of the Sn content is also pivotal for high performance,and the excess amount of Sn might generate additional acidic sites,which could decrease the propylene selectivity and lead to heavy coke formation.These findings provide deep insight into the design of highly selective and stable PDH catalysts.

Macrophage-derived exosomes modulate wear particle-induced osteolysis via miR-3470b targeting TAB3/NF-κB signaling

Aseptic prosthesis loosening(APL)is one of the most prevalent complications associated with arthroplasty.The main cause is the periprosthetic osteolysis induced by wear particles.However,the specific mechanisms of crosstalk between immune cells and osteoclasts/osteoblasts during osteolysis are unclear.In this study,we report the role and mechanism of macrophage-derived exosomes in wear particle-induced osteolysis.The results of exosomes up-taken experiments revealed that osteoblast and mature osteoclasts capture macrophage-derived exosomes(M-Exo).Next-generation sequencing and RT-qPCR on M-Exo revealed that exosomal microRNA miR-3470b was downregulated in wear particle-induced osteolysis.The results of analysis on Luciferase reporter assays/fluorescence in situ hybridization(FISH)/immunofluorescence(IF)/immunohistochemistry(IHC)and co-culture experiments demonstrated that wear particles induced osteoclast differentiation by increasing the expression of NFatc1 via M-Exo miR-3470b targeting TAB3/NF-κB signaling.We also illustrate that engineered exosomes enriching miR-3470b facilitated to suppressed the osteolysis;the microenvironment enriching with miR-3470b could suppress wear particle-induced osteolysis via inhibition of TAB3/NF-κB in vivo.In summary,our findings indicate that macrophage-derived exosomes transfer to osteoclasts to induce osteolysis in wear particle-induced APL.Engineering exosomes enriching with miR-3470b might be a novel strategy for the targeting treatment of bone resorption-related diseases.