No abstract

A deoxygenative gem-diborylation and gem-silylborylation of aldehydes and ketones is described. The key for the success of this transformation is the base-promoted C-O bond borylation or silylation of the generated α-oxyboronates. Experimental and theoretical studies exhibit that the C-O bond functionalization proceeds via an intramolecular five-membered transition-state (9-ts) boryl migration followed by a 1,2-metalate rearrangement with OBpin as a leaving group. The transformation occurs with an inversion on the carbon center. Direct conversion of aldehydes and ketones to gem-diboron compounds was achieved by combining copper catalysis with this base-promoted C-OBpin borylation. Various aldehydes and ketones were deoxygenatively gem-diborylated. gem-Silylborylation of aldehydes and ketones were achieved by a stepwise operation, in which Bpin initially react with those carbonyls followed by a silylation with Bpin-SiMePh.

Tumor resection is widely used to prevent tumor growth. However, the defected tissue at the original tumor site also causes tissue or organ dysfunction which lowers the patient’s life quality. Therefore, regenerating the tissue and preventing tumor recurrence are highly important. Herein, according to the concept of ‘first kill and then regenerate’, a versatile scaffold-based tissue engineering strategy based on cryogenic 3D printing of water-in-oil polyester emulsion inks, containing multiple functional agents, was developed, in order to realize the elimination of tumor cells with recurrence suppression and improved tissue regeneration sequentially. To illustrate our strategy, water/poly(lactic-co-glycolic acid)/dichloromethane emulsions containing β-tricalcium phosphate (β-TCP), 2D black phosphorus (BP) nanosheets, low-dose doxorubicin hydrochloride (DOX) and high-dose osteogenic peptide were cryogenically 3D printed into hierarchically porous and mechanically strong nanocomposite scaffolds, with multiple functions to treat bone tumor, resection-induced tissue defects. Prompt tumor ablation and long-term suppression of tumor recurrence could be achieved due to the synergistic effects of photothermotherapy and chemotherapy, and improved bone regeneration was obtained eventually due to the presence of bony environment and sustained peptide release. Notably, BP nanosheets in scaffolds significantly reduced the long-term toxicity phenomenon of released DOX during in vivo bone regeneration. Our study also provides insights for the design of multi-functional tissue engineering scaffolds for treating other tumor resection-induced tissue defects.

Emerging graphene/organic phototransistors are eye-catching technologies owing to their unique merits including easy/low-cost fabrication, temperature independent, and achieving various functions. However, their development in the near-infrared (NIR) region is experiencing a bottleneck of inferior sensitivity due to low exciton dissociation efficiency and inefficient charge extraction rate. Here, a novel-design solution-processed graphene/organic NIR phototransistor is reported, that is, creatively introducing electron extraction layer of ZnO on graphene channel and employing organic ternary bulk heterojunction as photosensitive layer, successfully breaking that bottleneck. The phototransistor exhibits a high responsivity of 6.1 × 10 6 A W −1 , a superior detectivity of 2.4 × 10 13 Jones, and a remarkable minimum detection power of 1.75 nW cm −2 under 850 nm radiation. Considering its excellent NIR detection performance, a noncontact transmission-type pulse monitoring is carried out with no external circuit support, from which human pulse signal and heart rate can be displayed in real time. The phototransistor, interestingly, can be switched into a photomemory function with a retention time of 1000 s in the atmosphere through a gate voltage of −20 V. The design takes the characteristics of graphene/organic phototransistors to a higher level, beyond the limit of sensitivity, and opens up a novel approach for developing multifunction devices.

Efficient solution-processed exciplex OLEDs were developed by incorporating a novel small molecule electron-donor and utilizing the strategy of ternary exciplexes.

Infrared upconversion devices (UCDs) enable low‐cost visualization of infrared optical signals without utilizing a readout circuit, which is of great significance for biological recognition and noninvasive dynamic monitoring. However, UCDs suffer from inferior photon to photon (p–p) efficiency and high turn‐on voltage (Von) for upconversion operation, hindering a further expansion in highly resolved infrared imaging. Herein, an efficient organic UCD integrating an interfacial exciplex emitter and a well‐designed near‐infrared (NIR) detector reveals a high efficiency up to 12.92% and a low Von down to 1.56 V. The low Von gives the capacity for detecting weak NIR light down to 3.2 µW cm–2, significantly expanding the detection power scale of UCDs. Thus, the imaging linear dynamic range (I‐LDR) is highly bias‐tunable, ranging from 13.23 to 84.4 dB. The high I‐LDR enables highly resolved and strong‐penetration bioimaging especially for thick biological sections, indicating great potential in noninvasive defect and pathological detection.

While scaffold-based tissue engineering has been widely used to treat bone critical-size defects, challenges such as implantation of scaffolds in defects with irregular shapes and implantation of scaffolds through minimally invasive surgery remain in the tissue engineering field. Customized bioactive bone tissue engineering scaffolds with reconfigurable capability for both easy scaffold implantation and perfect shape fitting in irregularly shaped bone defects are therefore needed. Herein, applying 4D printing, photothermal-responsive shape memory bone tissue engineering scaffolds are constructed by incorporating black phosphorus nanosheets and osteogenic peptide into β-tricalcium phosphate/poly(lactic acid-co-trimethylene carbonate) (TCP/P(DLLA-TMC)) nanocomposite scaffolds. When near-infrared irradiation is applied to customized scaffolds on-demand, scaffold temperature rapidly increases to 45 • C, enabling scaffold shape reconfiguration for easy scaffold implantation and precise fitting in irregular bone defects. Once the implantation is finished, scaffold temperature rapidly decreases to 37 • C and scaffolds display mechanical properties comparable to those of human cancellous bone. The improved osteogenesis in bone defect sites is then initiated through pulsed peptide release from scaffolds. Compact integration of reconfigurable scaffolds in rat cranial bone defects and improved new bone formation are demonstrated through micro-computed tomography and histochemical analyses. This study shows a facile method to clinically treat bone defects of irregular shapes.

Due to the increasing aging population and the high probability of sport injury among young people nowadays, it is of great demand to repair/regenerate diseased/defected osteochondral tissue. Given that osteochondral tissue mainly consists of a subchondral layer and a cartilage layer which are structurally heterogeneous and mechanically distinct, developing a biomimetic bi-phasic scaffold with excellent bonding strength to regenerate osteochondral tissue is highly desirable. Three-dimensional (3D) printing is advantageous in producing scaffolds with customized shape, designed structure/composition gradients and hence can be used to produce heterogeneous scaffolds for osteochondral tissue regeneration. In this study, bi-layered osteochondral scaffolds were developed through cryogenic 3D printing, in which osteogenic peptide/β-tricalcium phosphate/poly(lactic-co-glycolic acid) water-in-oil composite emulsions were printed into hierarchically porous subchondral layer while poly(D,L-lactic acid-co-trimethylene carbonate) water-in-oil emulsions were printed into thermal-responsive cartilage frame on top of the subchondral layer. The cartilage frame was further filled/dispensed with transforming growth factor-β1 loaded collagen I hydrogel to form the cartilage module. Although the continuously constructed osteochondral scaffolds had distinct microscopic morphologies and varied mechanical properties at the subchondral zone and cartilage zone at 37 °C, respectively, the two layers were closely bonded together, showing excellent shear strength and peeling strength. Rat bone marrow derived mesenchymal stem cells (rBMSCs) exhibited high viability and proliferation at both subchondral- and cartilage layer. Moreover, gradient rBMSC osteogenic/chondrogenic differentiation was obtained in the osteochondral scaffolds. This proof-of-concept study provides a facile way to produce integrated osteochondral scaffolds for concurrently directing rBMSC osteogenic/chondrogenic differentiation at different regions.