Potassium-Rich Iron Hexacyanoferrate/Carbon Cloth Electrode for Flexible and Wearable Potassium-Ion Batteries.

The fast development of flexible and wearable electronics increases the demand for flexible secondary batteries, and the emerging high-performance K-ion batteries (KIBs) have shown immense promise for the flexible electronics due to the abundant and cost-effective potassium resources. However, the implementation of flexible cathodes for KIBs is hampered by the critical issues of low capacity, rapid capacity decay with cycles, and limited initial Coulombic efficiency. To address these pressing issues, a freestanding K-rich iron hexacyanoferrate/carbon cloth (KFeHCF/CC) electrode is designed and fabricated by cathodic deposition. This innovative binder-free and self-supporting KFeHCF/CC electrode not only provides continuous conductive channels for electrons, but also accelerates the diffusion of potassium ions through the active electrode-electrolyte interface. Moreover, the nanosized potassium iron hexacyanoferrate particles limit particle fracture and pulverization to preserve the structure and stability during cycling. As a result, the K-rich KFeHCF/CC electrode shows a reversible discharging capacity of 110.1 mAh g-1 at 50 mA g-1 after 100 cycles in conjunction with capacity retention of 92.3% after 1000 cycles at 500 mA g-1 . To demonstrate the commercial feasibility, a flexible tubular KIB is assembled with the K-rich KFeHCF/CC electrode, and excellent flexibility, capacity, and stability are observed.

Transparent nanopaper for ultrashort pulse generation in the near-infrared region.

Transparent nanopaper (T-paper) can be applied in the field of electromagnetic shielding materials, antistatic materials, composite conductive materials, electric pool materials, super capacitors, and thermal management systems. However, this kind of T-paper has not been employed in ultrafast photonics yet. For the first time, to our knowledge, transparent electrical nanopaper is used in fiber lasers, different from the conventional pulsed fiber laser, which operates in the Q-switched regime under low pump power and then in the mode-locked regime under high pump power. Mode-locking is achieved first with a pulse duration of 550 fs under low pump power (166 mW). When further increasing the pump power up to 198 mW, the proposed fiber laser can be converted from a mode-locked to Q-switched state, which is a result of the two-photon absorption effect. The proposed fiber laser based on T-paper can be potentially applied in optical tomography, metrology, spectroscopy, micro-machining technology, and biomedical diagnostics.

A novel peptide-modified and gene-activated biomimetic bone matrix accelerating bone regeneration.

The osteogenic differentiation of bone marrow stromal cells (BMSCs) can be regulated by systemic or local growth factor, especially by transforming growth factor beta 1 (TGF-ß1). However, how to maintain the bioactivity of exogenous TGF-ß1 is a great challenge due to its short half-life time. The most promising solution is to transfer TGF-ß1 gene into seed cells through transgenic technology and then transgenic cells to continuously secret endogenous TGF-ß1 protein via gene expression. In this study, a novel non-viral vector (K)16GRGDSPC was chemically linked to bioactive bone matrices PLGA-[ASP-PEG]n using cross-linker to construct a novel non-viral gene transfer system. TGF-ß1 gene was incubated with this system and subsequently rabbit-derived BMSCs were co-cultured with this gene-activated PLGA-[ASP-PEG]n, while co-cultured with PLGA-[ASP-PEG]n modified with (K)16GRGDSPC only and original PLGA-[ASP-PEG]n as control. Thus we fabricated three kinds of composites: Group A (BMSCs-TGF-ß1DNA-(K)16GRGDSPC-PLGA-[ASP-PEG]n composite); Group B (BMSCs-(K)16GRGDSPC-PLGA-[ASP-PEG]n composite); and Group C (BMSCs-PLGA-[ASP-PEG]n composite). TGF-ß1 and other osteogenic phenotype markers of alkaline phosphatase, osteocalcin, osteopontin and type I collagen in Group A were all significantly higher than the other two groups ex vivo. In vivo, 15-mm long segmental rabbit bone defects were created and randomly implanted the aforementioned composites separately, and then fixed with plate-screws. The results demonstrated that the implants in Group A significantly accelerated bone regeneration compared with the other implants based on X-rays, histological and biomechanical examinations. Therefore, we conclude this novel peptide-modified and gene-activated biomimetic bone matrix of TGF-ß1DNA-(K)16GRGDSPC-PLGA-[ASP-PEG]n is a very promising scaffold biomaterial for accelerating bone regeneration.

Bone induction by biomimetic PLGA-(PEG-ASP)n copolymer loaded with a novel synthetic BMP-2-related peptide in vitro and in vivo.

BMP-2 is one of the most important growth factors of bone regeneration. Polylactide-co-glycolic acid (PLGA), which is used as a biodegradable scaffold for delivering therapeutic agents, has been intensively investigated. In previous studies, we synthesized a novel BMP-2-related peptide (designated P24) and found that it could enhance the osteoblastic differentiation of bone marrow stromal cells (BMSCs). The objective of this study was to construct a biomimetic composite by incorporating P24 into a modified PLGA-(PEG-ASP)n copolymer to promote bone formation. In vitro, our results demonstrated that PLGA-(PEG-ASP)n scaffolds were shown to be an efficient system for sustained release of P24. Significantly more BMSCs attached to the P24/PLGA-(PEG-ASP)n and PLGA-(PEG-ASP)n membranes than to PLGA, and the cells in the two groups subsequently proliferated more vigorously than those in the PLGA group. The expression of osteogenic markers in P24/PLGA-(PEG-ASP)n group was stronger than that in the PLGA-(PEG-ASP)n and PLGA groups. Radiographic and histological examination, Western blotting and RT-PCR showed that P24/PLGA-(PEG-ASP)n scaffold could induce more effective ectopic bone formation in vivo, as compared with PLGA-(PEG-ASP)n or gelatin sponge alone. It is concluded that the PLGA-(PEG-ASP)n copolymer is a good P24 carrier and can serve as a good scaffold for controlled release of P24. This novel P24/PLGA-(PEG-ASP)n composite promises to be an excellent biomaterial for inducing bone regeneration.

[Adhesion, proliferation and osteodifferentiation of bone mesenchymal stem cells on PLGA-[ASP-PEG] tri-bolck polymer scaffolds].

OBJECTIVE: To explore the adhesion,proliferation and osteodifferentiation of bone mesenchymal stem cells (BMSCs)on the prepared lactic acid/glycolic acid/asparagic acid-co-polyethylene glycol(PLGA-[ASP-PEG])tri-block polymer scaffolds. METHODS: Modified PLGA with polyethylene glycol (PEG) and asparagic acid(ASP)that has many liga nds,and then the synthesis PLGA-[ASP-PEG] tri-block polymer material was prepared. BMSCs were cultured in PLGA-[ASP-PEG] polymer material and poly lactic acid-co-glycolic acid(PLGA)were used as control group. Precipitation method, MUT assay and total cellular protein detection were used to test the adhersion and proliferation of BMSCs. After the third generation of BMSCs was cultured on PLGA-[ASP-PEG] tri-block polymer scaffolds for 14 day and 28 day with osteogenic supplements,the osteodifferentiation of MSCs were observed through alkaline phosphatase(ALP) staining and calcium tubercle staining. RESULTS: BMSCs grew adherent to the surface of PLGA-[ASP-PEG] polymer scaffolds and the number of BMSCs was much higher than that of PLGA. The precipitation method suggested that adhesion and proliferation of BMSCs on the surface of PLGA-[ASP-PEG] was much higher than the control group (P < 0.05). MTU assay showed that after BMSCs were cultured for 20 days,the absorbance A of PLGA-[ASP-PEG] polymer scaffolds and PLGA were 1.336 and 0.780 respectively. Total cellular protein could image the adhersion and proliferation of BMSCs indirectly. After BMSCs were cultured for 12 days,the total cellular protein of PLGA-[ASP-PEG] and PLGA were 66.44 microg/pore and 41.23 microg/pore respectively. PLGA-[ASP-PEG] polymer scaffolds had well biocompatibility and cell adhersion. The positive results with ALP staining and calcium tubercle staining in both groups indicated tri-block polymer scaffold and its degradations had no effect on osteodifferentiation. CONCLUSION: PLGA-[ASP-PEG]could improve the adhesion and proliferation of seed cells on bone-matrixmaterial, maintain the morphous of seed cells and had no obvious effect on cell osteodifferentiation.

Repair of rabbit femoral defects with a novel BMP2-derived oligopeptide P24.

In this study, the bioactivity of a novel BMP2-derived oligopeptide P24 was investigated by using the model of rabbit femoral defect after loaded in the biodegradable poly (lactic acid / glycolic acid / asparagic acid-co-polyethylene glycol) (PLGA-[ASP-PEG]). A 1.5-cm unilateral segmental bone defect was created in the left femoral diaphysis in each of the 30 new zealand white rabbits. The defects of 18 legs filled with BMP2-derived peptide P24 combined with PLGA-[ASP-PEG] scaffold serves as the experimental group, and the defects in the rest 12 rabbits filled with (PLGA-[ASP-PEG]) without P24 as control group. The bone-repairing capability in the target region of the two group was grossly, radiologically, histopathologically and biomechanically evaluated 4, 8 and 12 weeks after the operation. Our results showed that in each group, primary healing of incision was achieved in the two groups. Radiographically, in experimental group, defects were filled with induced callus within 8 weeks, and a cortical bone-like structure was observed in some animals at the 12th week. According to the standardized stage of bone defect repair, 9 (64.28%) achieved grade-4 healing. In contrast, little bone formation was seen in the defects even 12 weeks after the operation, and 5 (62.50%) had grade 0 healing in this group. Histologically, tissue engineering material was mostly absorbed and cartilage was found around implants in the experimental group at the 4th week; 8 weeks after operation, the engineering material was completely absorbed, and formation of woven bone was observed and typical trabecular bone structure could be seen. In control group, 8 weeks after operation, the defect was filled with fibrous tissues, and no bone-like structure was observed. Statistical analysis showed very significant difference in biomechanical indicators between the two groups (P<0.05). It is concluded that new oligopeptide P24 can induce excellent bone regeneration and promote bone repair.

Repair of Rabbit Femoral Defects with a Novel BMP2-derived Oligopeptide P24 / 华中科技大学学报（医学）（英德文版）

In this study, the bioactivity of a novel BMP2-derived oligopeptide P24 was investigated by using the model of rabbit femoral defect after loaded in the biodegradable poly (lactic acid / glycolic acid / asparagic acid-co-polyethylene glycol) (PLGA-[ASP-PEG]). A 1.5-cm unilateral segmental bone defect was created in the left femoral diaphysis in each of the 30 new zealand white rabbits.The defects of 18 legs filled with BMP2-derived peptide P24 combined with PLGA-[ASP-PEG]scaffold serves as the experimental group, and the defects in the rest 12 rabbits filled with(PLGA-[ASP-PEG]) without P24 as control group. The bone-repairing capability in the target region of the two group was grossly, radiologically, histopathologically and biomechanically evaluated 4, 8and 12 weeks after the operation. Our results showed that in each group, primary healing of incision was achieved in the two groups. Radiographically, in experimental group, defects were filled with induced callus within 8 weeks, and a cortical bone-like structure was observed in some animals at the12th week. According to the standardized stage of bone defect repair, 9 (64.28%) achieved grade-4healing. In contrast, little bone formation was seen in the defects even 12 weeks after the operation,and 5 (62.50%) had grade 0 healing in this group. Histologically, tissue engineering material was mostly absorbed and cartilage was found around implants in the experimental group at the 4th week;8 weeks after operation, the engineering material was completely absorbed, and formation of woven bone was observed and typical trabecular bone structure could be seen. In control group, 8 weeks after operation, the defect was filled with fibrous tissues, and no bone-like structure was observed. Statistical analysis showed very significant difference in biomechanical indicators between the two groups (P＜0.05). It is concluded that new oligopeptide P24 can induce excellent bone regeneration and promote bone repair.

[Dose-dependence of bone morphogenetic protein 2-derived peptide on osteogenic induction in marrow mesenchymal stem cells in vitro].

OBJECTIVE: To investigate the effect of the synthetic bone morphogenetic protein 2 (BMP-2)-derived peptide on the osteogenic induction in the marrow mesenchymal stem cells (MSCs) and to evaluate the osteoinductivity and dose-dependence of the BMP-2-derived peptide in vitro. METHODS: MSCs of 4-week old Wistar rats were separated and cultured. In the 3rd passage, the conditional culture medium was changed, in which the BMP-2-derived peptide in the following doses was added: 300,200, 100, 50, and 0 microg/ml, respectively (Groups A-E). The activity of alkaline phosphatase (ALP)and the amount of calcium deposition were meassured at 5, 10, 15 and 20 days during the culture with the conditional culture medium. The real-time fluorescent quantitative polymerase chain reaction (FQ-PCR) was performed to measure the mRNA expressions of collagen type I, osteopontin (OPN), and osteocalcin (OCN) and to measure the osteoinductivity of the BMP-2-derived peptide in the different concentrations. RESULTS: Under the inverted phase contrast microscope, MSCs cultured in the conditional culture medium for 3-4 days were changed in shape, from long fusiform to short fusiform or polygon. As the concentration of the BMP-2-derived peptide increased, the time for MSCs to change into the osteoblasts decreased. There was a significantly greater level of the ALP activity and amount of the calcium deposition in Groups A and B than in the other groups (P < 0.05). However, there was no significant difference between Group A and Group B (P > 0.05). The result of FQ-PCR showed that after MSCs were cultured in the different doses of the conditional culture medium for 14 days, the mRNA expressions of collagen type I, OPN and OCN were at higher levels. An increasing order in the level of the cycle threshold (Ct) was found in the following groups: A > B > C > D). Almost no expression was found in Group E. The Ct levels were significantly greater in Groups A and B than in Groups C and D (P < 0. 05). However, there was no significant difference between Group A and Group B (P > 0.05). CONCLUSION: The BMP-2-derived peptide can greatly promote differentiation of MSCs into the osteoblasts, the promotion of osteogenesis has a dose-dependent pattern, and the best inducing dosage is 200 microg/ml.

Experimental research on ectopic osteogenesis of BMP2-derived peptide P24 combined with PLGA copolymers.

To experimentally evaluate the ectopic osteogenetic capacity of synthesized BMP2-derived peptide P24 combined with poly lactic-co-glycolic acid (PLGA), Wistar rats were divided into two groups: group A, in which BMP2-derived peptide P24/PLGA complex was implanted, and group B which received simple PLGA implant. The complex was respectively implanted into the back muscles of rats. Samples were taken the 1st, 4th, 8th, and the 12th week after the implantation. Their bone formation was detected by X-ray examination, and tissue response was histologically observed. Western blotting was used for the detection of the expression of collagen I (Col-I) and osteopontin (OPN). There was acute inflammation in the tissue around both types of implants at early stage. The cartilage was found around implant areas 4 weeks after the implantation of BMP2-derived peptide p24/PLGA complex, 8 weeks after the implantation, osteoblasts were found, and 12 weeks after the implantation, typical trabecular bone structure was observed. In group B, after 12 weeks, no osteoblasts were found. It is concluded that PLGA is an ideal scaffold material for bone tissue engineering. BMP2-derived peptide can start endochondral ossification and is more effective in inducing ectopic osteogenesis.