Synergistic effects of laser powder bed fusion and annealing on the texture-selective recrystallization of magnetostrictive Fe-Ga-NbC alloys for biomedical applications.

INTRODUCTION: Magnetostrictive Fe-Ga alloys have garnered extensive attention owing to their excellent magnetic properties and acceptable biocompatibility. Nevertheless, the polycrystalline Fe-Ga alloys currently available tend to display random texture orientations, which constrain their magnetostrictive performance. OBJECTIVES: To regulate the texture orientation of Fe-Ga-NbC alloys and thereby enhancing magnetostriction. METHODS: In this study, a processing route comprising laser powder bed fusion (LPBF) followed by secondary recrystallization annealing (800, 1000, and 1200 °C, respectively) was developed to prepare Fe-Ga-NbC alloys. RESULTS: The results showed that the LPBF-ed (Fe81Ga19)99(NbC)1 alloys exhibited a high content of high energy grain boundaries (HEGBs) due to the repeated melting and solidification. In subsequent annealing process, the migration of HEGBs induced the rearrangement and recrystallization of grains, during which NbC was found to locate at the grain boundaries and influence the migration path of HEGBs via selective pinning, thereby resulting in a strong Goss texture. With the rise in annealing temperature, the content of Goss texture gradually increased from the initial 3.9 % to 71.3 % at 1200 °C, leading to enhanced magnetostriction, lower saturation magnetization and coercivity. Furthermore, in alternating magnetic fields, the alloys annealed at 1200 °C also exhibited higher magnetostriction than the LPBF-ed alloys. And a noteworthy grain coarsening was also observed after annealing, accompanied by a discernible inclination of magnetic domains towards strip domains. Additional, cell tests demonstrated that the prepared alloys had satisfactory biocompatibility and the ability to promote osteogenic differentiation. CONCLUSION: These findings indicated that the LPBF-ed and annealed Fe-Ga-NbC alloys might be a promising alternative as magnetostrictive-driven materials for biomedical applications.

Research on the application of inertially stabilized platform in the dynamic measurement of cold atomic gravimeter.

Dynamic gravity field measurement based on the cold atom absolute gravity measurement system has important applications in geological exploration, gravity field mapping and other fields. The inertial stabilized platform is the key component of the dynamic cold atom absolute gravity measurement system, which can isolate the interference of carrier angle motion and keep the atomic gravimeter probe in the horizontal attitude during the measurement process. In this paper, according to the dynamic measurement requirements of atomic gravimeter, a high-precision two-axis inertial stabilized platform system is designed. The relationship between attitude angle and gravity measurement error is analyzed, and the stability of the system is enhanced by lead-lag method. Then the static vertical vibration power spectrum of the platform is measured to consider its influence on dynamic gravity measurement. Finally, a dynamic gravity test experiment was conducted in the Yellow Sea to verify the attitude control accuracy of the platform, and the attitude data of the platform under different heading were evaluated. The attitude standard deviation of the platform was better than 4 × 10-5 rad, and the absolute gravity standard deviation of the linear round-trip measurement reached 1.49 mGal. The experimental data show that the inertial stabilized platform can meet the dynamic measurement requirements of the cold atom gravimeter.

Oxygen vacancy healing boosts the piezoelectricity of bone scaffolds.

Although barium titanate (BaTiO3) presented tremendous potential in achieving self-powered stimulation to accelerate bone repair, pervasive oxygen vacancies restricted the full play of its piezoelectric performance. Herein, BaTiO3-GO nanoparticles were synthesized by the in situ growth of BaTiO3 on graphene oxide (GO), and subsequently introduced into poly-L-lactic acid (PLLA) powders to prepare PLLA/BaTiO3-GO scaffolds by laser additive manufacturing. During the synthesis process, CO and C-OH in GO would respectively undergo cleavage and dehydrogenation at high temperature to form negatively charged oxygen groups, which were expected to occupy positively charged oxygen vacancies in BaTiO3 and thereby inhibit the formation of oxygen vacancies. Moreover, GO could be partially reduced to reduced graphene oxide, which could act as a conductive phase to facilitate polarization charge transfer, thus further improving the piezoelectric performance. The results showed that the oxygen peak at the specific electron binding energy in O 1s declined from 54.4% to 14.6% and the Ti3+ peak that was positively correlated with oxygen vacancies apparently weakened for BaTiO3-GO, illustrating that the introduced GO significantly decreased the oxygen vacancy. As a consequence, the piezoelectric current of PLLA/BaTiO3-GO increased from 80 to 147.3 nA compared with that of PLLA/BaTiO3. The enhanced piezoelectric current effectively accelerated cell differentiation by upregulating alkaline phosphatase expression, calcium salt deposition and calcium influx. This work provides a novel insight for the design of self-powered stimulation scaffolds for bone regeneration.

Suppression of the SLC7A11/glutathione axis causes ferroptosis and apoptosis and alters the mitogen-activated protein kinase pathway in nasopharyngeal carcinoma.

SLC7A11 is a unit of the glutamate cystine antiporter Xc- system. It functions to import cystine for glutathione biosynthesis and maintains the redox balance in cells. Sorafenib inhibits the transporter activity of SLC7A11. The use of sorafenib has been approved in the treatment of multiple cancers. However, at present, our understanding of the mechanism of SLC7A11 and sorafenib in nasopharyngeal carcinoma (NPC) remains limited. We found that the expression of SLC7A11 was upregulated in NPC. A high SLC7A11 expression was associated with poor prognosis, metastasis, and an advanced T stage, which can be used as an independent prognostic indicator of NPC. In vitro, we observed that NPC cells relied on cystine for survival. Targeting SLC7A11 resulted in glutathione biosynthesis limitation, intracellular reactive oxygen species accumulation, lipid peroxides, ferroptosis, and apoptosis. Meanwhile, it altered mitogen activated protein kinase pathway, including p38 activation but ERK inhibition in NPC. This limited the proliferation of NPC cells. Sorafenib inhibited the proliferation and induced the death of NPC cells in vivo. In conclusion, SLC7A11 plays an important role in the occurrence and progression of NPC and may be a novel target for NPC treatment.

A CuS@g-C3N4 heterojunction endows scaffold with synergetic antibacterial effect.

Graphitic carbon nitride (g-C3N4) had aroused tremendous attention in photodynamic antibacterial therapy due to its excellent energy band structure and appealing optical performance. Nevertheless, the superfast electron-hole recombination and dense biofilm formation abated its photodynamic antibacterial effect. To this end, a nanoheterojunction was synthesized via in-situ growing copper sulfide (CuS) on g-C3N4 (CuS@g-C3N4). On the one hand, CuS could form Fermi level difference with g-C3N4 to accelerate carrier transfer and thus facilitate electron-hole separation. On the other hand, CuS could respond near-infrared light to generate localized thermal to disrupt biofilm. Then the CuS@g-C3N4 nanoparticle was introduced into the poly-l-lactide (PLLA) scaffold. The photoelectrochemistry results demonstrated that the electron-hole separation efficiency was apparently enhanced and thereby brought an approximate sevenfold increase in reactive oxygen species (ROS) production. The thermal imaging indicated that the scaffold possesses a superior photothermal effect, which effectively eradicated the biofilm by disrupting its extracellular DNA and thereby facilitated to the entry of ROS. The entered ROS could effectively kill the bacteria by causing protein, K+, and nucleic acid leakage and glutathione consumption. As a consequence, the scaffold displayed an antibacterial rate of 97.2% and 98.5% against E. coli and S. aureus, respectively.

Role of ß-catenin in PD-L1 expression of nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is a particular type of tumor connected to Epstein-Barr virus infection, genetic, and environmental factors. It is typically discovered late, with few therapeutic options and poor clinical outcomes. Cellular immune responses can be attenuated when programmed death ligand 1 (PD-L1) and programmed cell death protein 1 (PD-1) are combined. Although PD-1 inhibitors have a different anti-tumor response rate than chemotherapy alone, they can nevertheless considerably outperform chemotherapy in patients with metastatic or recurrent NPC. The nuclear ß-catenin can bind to the CD274 promoter region, promoting transcription and upregulating the expression of tumor-specific PD-L1. Separation of ß-catenin from E-cadherin and translocation it into nucleus were both aided by ß-catenin phosphorylates at the Tyr654 site. Its function in NPC and the expression of PD-L1 have not yet been investigated. This study investigated the predictive significance of PD-L1 and p-ß-cateninTyr654 expressions in NPC. Our findings indicated that patients with distant metastases or poor prognoses exhibited higher levels of PD-L1 and p-ß-cateninTyr654 expressions. According to Cox multivariate prognostic analysis, PD-L1 was also an effective indicator for predicting the survival status of patients with NPC. We subsequently demonstrated that PD-L1 transcription and protein production could be downregulated by targeting inhibition of the level of ß-catenin in NPC cells. This is for developing the ß-catenin or TCF4 inhibitor as a potential new option for immune checkpoint immunosuppression in NPC.

Lnc-PPP2R1B Mediates the Alternative Splicing of PPP2R1B by Interacting and Stabilizing HNRNPLL and Promotes Osteogenesis of MSCs.

Osteogeinc differentiation from mesenchymal stem cells (MSCs) into osteoblasts is a key step for bone tissue engineering in regenerative medicine. The insight into regulatory mechanism of osteogenesis of MSCs facilitates achieving better recovery effect. Long non-coding RNAs are regarded as a family of important moderators in osteogenesis. In this study, we found a novel lncRNA, lnc-PPP2R1B was up-regulated during osteogenesis of MSCs by Illumina HiSeq transcritome sequencing. We demonstrated lnc-PPP2R1B overexpression promoted osteogenesis and knockdown of lnc-PPP2R1B inhibited osteogenesis of MSCs. Mechanically, it physically interacted with and up-regulated heterogeneous nuclear ribonucleoprotein L Like (HNRNPLL), which is a master regulator of activation-induced alternative splicing in T cells. We found lnc-PPP2R1B knockdown or HNRNPLL knockdown decreased transcript-201 of Protein Phosphatase 2A, Regulatory Subunit A, Beta Isoform (PPP2R1B) while increased transcript-203 of PPP2R1B, and did not affect transcript-202/204/206. PPP2R1B is a constant regulatory subunit of protein phosphatase 2 (PP2A), which activates Wnt/ß-catenin pathway by removing phosphorylation and stabilization of ß-catenin and translocation into nucleus. The transcript-201 retained exon 2 and 3, compared to transcript-203. And it was reported the exon 2 and 3 of PPP2R1B were one part of B subunit binding domain on A subunit in PP2A trimer, and therefore retaining exon 2 and 3 promised formation and enzyme function of PP2A. Finally, lnc-PPP2R1B promoted ectopic osteogenesis in vivo. Conclusively, lnc-PPP2R1B mediated alternative splicing of PPP2R1B through retaining exon 2 and 3 by interacting with HNRNPLL and then promoted osteogenesis, which may facilitate an in-depth understanding of function and mechanism of lncRNAs in osteogenesis. Lnc-PPP2R1B interacted with HNRNPLL, and regulated alternative splicing of PPP2R1B through retaining exon 2 and 3, which preserved enzyme function of PP2A and enhanced dephosphorylation and nuclear translocation of ß-catenin, thereby promoting Runx2 and OSX expression and then osteogenesis. And it provided experimental data and potential target for promoting bone formation and bone regeneration.

Fe-doped mesoporous silica catalyzes ascorbic acid oxidation for tumor-specific therapy in scaffold.

Ascorbic acid (AA) is a promising antitumor agent, yet its autooxidation is too slow which constrains the further application. Fortunately, the autoxidation process can be accelerated by transition metal catalysts, especially Fe3+ ions. In this study, AA was loaded to Fe-doped mesoporous silica (designated as AA@Fe-SiO2), which was introduced into poly-L-lactic acid (PLLA) and then prepared into a scaffold. Mechanistically, AA@Fe-SiO2 degraded in acidic tumor microenvironment because excessive H+ substituted Fe atoms in the iron silicate framework, releasing Fe3+ and AA. The Fe3+ boosted the pro-oxidation reaction of AA, generating numerous hydrogen peroxide (H2O2) and Fe2+. Then, Fe2+ reacted with H2O2 to initiate Fenton reactions favoring hydroxyl radical generation, triggering oxidative damage on tumor cells to implement tumor-specific therapy. Results showed that the release amount of AA in acidic solution was about 3 times higher than that in neutral solution, which was attributed to the pH-dependency of the degradation of AA@Fe-SiO2 in scaffold. Furthermore, the scaffold generated numerous ascorbate radical intermediate and increased the H2O2 concentration by 120.2%, demonstrating that Fe3+ remarkably accelerated the oxidation rate of AA. Cell experimental results showed that the scaffold caused massive apoptosis of tumor cells, while no obvious cytotoxicity to normal cells, confirming the antitumor specificity of scaffold. This work paves a promising way to construct a biodegradable and catalytic scaffold, featuring effective tumor-specific therapy.

The association and clinical relevance of phase-separating protein CAPRIN1 with noncoding RNA.

CAPRIN1, cell cycle-associated protein 1, is an RNA-binding protein in stress granules, P bodies, and messenger RNA transport granules and has a high level of expression in cancer. It promotes the proliferation and invasion of cancer cells and enhances their glycolysis and chemoresistance. In addition, it mediates the formation of intracellular SGs in various ways when exposed to endogenous and exogenous stress. As an RNA-binding protein, it not only directly binds to several mRNAs associated with the cell cycle but also is the target of miRNA, lncRNA, and circRNA. Recently, CAPRIN1 is identified as a phase-separating protein that mediates the liquid-liquid phase separation within tumor cells. Moreover, the formation of CAPRIN1-mediated phase separation is regulated by circRNA and lncRNA. In addition, CAPRIN1 is associated with ubiquitination, which affects the relevant characteristics of cancer cells. This review discusses the different regulatory mechanisms of CAPRIN1 in various tumors and its association with noncoding RNA, suggesting its potential as an oncogenic signal and possibly as a diagnostic indicator in the future. This may provide the multifunctional characteristic insight of CAPRIN1 protein and potential therapeutic target in malignancy with high levels of CAPRIN1.

A spatiotemporal drug release scaffold with antibiosis and bone regeneration for osteomyelitis.

INTRODUCTION: Scaffolds loaded with antibacterial agents and osteogenic drugs are considered essential tools for repairing bone defects caused by osteomyelitis. However, the simultaneous release of two drugs leads to premature osteogenesis and subsequent sequestrum formation in the pathological situation of unthorough antibiosis. OBJECTIVES: In this study, a spatiotemporal drug-release polydopamine-functionalized mesoporous silicon nanoparticle (MSN) core/shell drug delivery system loaded with antibacterial silver (Ag) nanoparticles and osteogenic dexamethasone (Dex) was constructed and introduced into a poly-l-lactic acid (PLLA) scaffold for osteomyelitis therapy. METHODS: MSNs formed the inner core and were loaded with Dex through electrostatic adsorption (MSNs@Dex), and then polydopamine was used to seal the core through the self-assembly of dopamine as the outer shell (pMSNs@Dex). Ag nanoparticles were embedded in the polydopamine shell via an in situ growth technique. Finally, the Ag-pMSNs@Dex nanoparticles were introduced into PLLA scaffolds (Ag-pMSNs@Dex/PLLA) constructed by selective laser sintering (SLS). RESULTS: The Ag-pMSNs@Dex/PLLA scaffold released Ag+ at the 12th hour, followed by the release of Dex starting on the fifth day. The experiments verified that the scaffold had excellent antibacterial performance against Escherichia coli and Staphylococcus aureus. Moreover, the scaffold significantly enhanced the osteogenic differentiation of mouse bone marrow mesenchymal stem cells. CONCLUSION: The findings suggested that this spatiotemporal drug release scaffold had promising potential for osteomyelitis therapy.

Silicon dioxide nanoparticles decorated on graphene oxide nanosheets and their application in poly(l-lactic acid) scaffold.

INTRODUCTION: The aggregation of graphene oxide (GO) is considered as main challenge, although GO possesses excellent mechanical properties which arouses widespread attention as reinforcement for polymers. OBJECTIVES: In this study, silicon dioxide (SiO2) nanoparticles were decorated onto surface of GO nanosheets through in situ growth method for promoting dispersion of GO in poly(l-lactic acid) (PLLA) bone scaffold. METHODS: Hydroxyl and carboxyl functional groups of GO provided sites for SiO2 nucleation, and SiO2 grew with hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) and finally formed nanoparticles onto surface of GO with covalent bonds. Then, the GO@ SiO2 nanocomposite was blended with PLLA for the fabrication of bone scaffold by selective laser sintering (SLS). RESULT: The results indicated that the obtained SiO2 were distributed relatively uniformly on surface of GO under TEOS concentration of 0.10 mol/L (GO@SiO2-10), and the covering of SiO2 on GO could increase interlayer distance of GO nanosheets from 0.799 nm to 0.894 nm, thus reducing van der Waals forces between GO nanosheets and facilitating the dispersion. Tensile and compressive strength of scaffold containing GO@SiO2 hybrids were significantly enhanced, especially for the scaffold containing GO@SiO2-10 hybrids with enhancement of 30.95 % in tensile strength and 66.33 % in compressive strength compared with the scaffold containing GO. Additionally, cell adhesion and fluorescence experiments demonstrated excellent cytocompatibility of the scaffold. CONCLUSIONS: The good dispersion of GO@SiO2 enhances the mechanical properties and cytocompatibility of scaffold, making it a potential candidate for bone tissue engineering applications.

Highly Dispersed Cu Produced by Mechanical Stress-Activated Redox Reaction to Establish Galvanic Corrosion in Fe Implant.

Fe has immense potential for biodegradable orthopedic applications, but it degrades slowly in the physiological environment. Inducing galvanic couple by alloying Cu to Fe using ball milling is a promising approach. However, the ductile nature of Cu leads to the cold welding of a large amount of Cu powder during ball milling, which makes it difficult to disperse uniformly in the Fe matrix. Here, a Fe-CuO implant with highly dispersed Cu particles in the matrix was developed by shift-speed ball milling and selective laser melting. Specifically, copper oxide (CuO) particles were selected as precursors and dispersed in Fe powders by ball milling since they were brittle and would not be cold-welded during ball milling. After further milling in higher energy, it was found that CuO particles reacted with Fe and generated Cu particles through a stress-activated redox reaction. Subsequently, the obtained powders were prepared into a Fe-CuO implant using selective laser melting. Microstructure examination revealed that the Cu phases in the implant were dispersed evenly in the Fe matrix, which was considered to establish a large number of galvanic couples and aggravated the galvanic corrosion tendency. Electrochemical tests indicated that the implant had improved performance in degradation behavior in terms of high corrosion current density (22.4 µA/cm2), low corrosion resistance (1319 Ω cm2), and good degradation stability. In addition, it presented antibacterial effects against Escherichia coli and Staphylococcus aureus by diffusion mechanisms with killing rates of 90.7 and 96.7%, respectively, as well as good cytocompatibility.

Accelerated anode and cathode reaction due to direct electron uptake and consumption by manganese dioxide and titanium dioxide composite cathode in degradation of iron composite.

The movement towards the clinical application of iron (Fe) has been hindered by the slow degradation rate in physiological environments. Herein, manganese dioxide (MnO2) particles were compounded with titanium dioxide (TiO2) particles by mechanical ball milling, and then the mixed powders were incorporated into Fe and fabricated into an implant using selective laser melting. On the one hand, MnO2 had a higher work function (5.21 eV) than Fe (4.48 eV), which inclined electrons to transfer from Fe to MnO2 to accelerate the anode reaction. On the other hand, MnO2 catalysed the oxygen reduction reaction (ORR) through a four-step proton-electron-coupled reaction, which caused more oxygen to flow into the sample to improve the cathode performance. Besides, anatase TiO2 with high conductivity was compounded with MnO2 to construct a composite cathode, which facilitated electron transport from the cathode to the electrolyte, further consuming electrons and promoting cathode reaction. Results showed that Fe-MnO2-TiO2 had a high limiting current density of 5.32 mA·cm-2 and a large half-wave potential of -767.4 mV, indicating an enhanced ORR activity. More significantly, Fe-MnO2-TiO2 had a higher average electron transfer number (2.9) than Fe-MnO2 (2.5), demonstrating a faster electronic consumption reaction and higher cathode performance. In addition, the Fe-MnO2-TiO2 also exhibited fast instantaneous and long-term degradation rates (0.33 ± 0.03 and 0.19 ± 0.02 mm/year), suggesting a high anode dissolution rate. In conclusion, introducing the cathode with high work function and ORR activity provides novel pathways for accelerating the degradation rate of Fe-based implants.

Targeting ALDH1A1 to induce Necroptosis in Nasopharyngeal Carcinoma.

ALDH1A1 is one of the highly conserved isoenzymes of the aldehyde dehydrogenase family. It is mainly involved in the metabolism of intracellular aldehydes and forms transcriptional regulators, which are essential for growth and differentiation of normal cells. Overexpression of ALDH1A1 in many malignancies and cancer stem cells (CSCs) is closely associated with poor prognosis and promotes tumor aggressiveness and drug resistance during conventional cancer chemotherapy. In this study, we found that ALDH1A1 had tumor suppressor effects in BRCA, CESC, LIHC, Lung cancer, renal cell carcinoma and PAAD, but tumor-promoting effects in SKCM, GBM, THCA and BLCA. As for the nasopharyngeal carcinoma, ALDH1A1 mainly played a carcinogenic role. We found that although the expression of ALDH1A1 in NPC tissue was lower than that in normal nasopharyngeal mucosal tissue, it was upregulated in patients with higher clinical stages, and correlated with poor patient outcomes. Therefore, we further analyzed the main possible role of ALDH1A1 in NPC by taking GSE12452 dataset. The GSEA enrichment analysis showed that it could inhibit the necroptosis of nasopharyngeal carcinoma cells. Therefore, we used the targeted inhibitor NCT-501 and found that it could inhibit the proliferation and stem cell spheroidization of NPC cells, and induce necroptosis. This study explored the possible role of ALDH1A1 in various tumors and focused on its potential role as a target in NPC. Meanwhile, ALDH1A1 inhibitor preferentially has potential therapeutic value in NPC.

ARL4C depletion suppresses the resistance of ovarian cancer to carboplatin by disrupting cholesterol transport and autophagy via notch-RBP-Jκ-H3K4Me3-OSBPL5.

Increasing studies indicate that cholesterol plays an important role in drug resistance. ARL4C is implicated in the export and import of cholesterol, therefore this study aimed to explore the effect of ARL4C on the resistance of ovarian cancer (OVC) to Carboplatin. This study collected OVC tissue samples from patients who are sensitive or resistant to carboplatin, and established Carboplatin-resistant OVC cell lines, OVCAR3(R) and SKOV3(R) using OVCAR3 and SKOV3. High throughput sequencing was conducted to find genes that regulated by ARL4C. Cholesterol esterification was performed to evaluate the transport of cholesterol from Lysosome (LY) to Endoplasmic reticulum (ER). The fluorescence of LC3-GFP-mRFP was used to evaluate the function of autophagy flux. As indicated by PCR, western blot and Immunohistochemistry, ARL4C was increased in the Carboplatin-resistant OVC tissues and cells. Knockdown of ARL4C attenuated the resistance of OVCAR3(R) and SKOV3(R) to Carboplatin. By suppressing Notch signal, ARL4C knockdown inhibited the transcriptional function of RBP-Jκ and RBP-Jκ-induced H3K4Me3, which collectively reduced OSBPL5 expression. OSBPL5 deficiency inhibited the transport of cholesterol from LYs to ER, which led to the accumulation of cholesterol in LYs and the dysfunction of autophagy. In summary, ARL4C knockdown attenuated the resistance of OVC to Carboplatin by disrupting cholesterol transport and autophagy. This study revealed a promising target to attenuate the resistance of OVC to Carboplatin and elucidated the potential mechanism.

Photoexcited wireless electrical stimulation elevates nerve cell growth.

Electrical stimulation was restrained by an external power supply and wires, despite its ability to promote nerve cell growth. Bismuth sulfide (Bi2S3) offered a novel prospect for achieving wireless electrical stimulation due to its photoelectric effect. Herein, silver nanoparticles (Ag NPs) were in-situ grown on Bi2S3 surface (Ag/Bi2S3) and then mixed with poly-L-lactic acid (PLLA) powders to fabricate PLLA-Ag/Bi2S3 conduits. On the one hand, Bi2S3 would generate photocurrent under light excitation, forming a wireless electrical stimulation. On the other hand, Ag NPs would form localized electrical fields under light excitation to inhibit rapid electron-hole recombination of Bi2S3. Moreover, Ag NPs would act as electron mediators to accelerate electron transfer, further elevating photocurrent. Electrochemical tests and FDTD simulations revealed the localized electrical fields generated by Ag NPs acted on Bi2S3, resulting in a boosted electron-hole separation evidenced by a reduction in photoluminescence intensity. EIS measurements demonstrated a faster electron transfer occurred on Ag/Bi2S3. As a result, the photocurrent of PLLA-Ag/Bi2S3 increased from 0.26 to 1.03 µA as compared with PLLA-Bi2S3. The enhanced photocurrent effectively promoted cell differentiation by up-regulating Ca2+ influx and nerve growth-related protein SYN1 expression. This work suggested a promising countermeasure in the design of photocurrent stimulation conduits for nerve repair.

A Codispersed Nanosystem of Silver-anchored MoS2 Enhances Antibacterial and Antitumor Properties of Selective Laser Sintered Scaffolds.

Tumor recurrence and bacterial infection are common problems during bone repair and reconstruction after bone tumor surgery. In this study, silver-anchored MoS2 nanosheets (Ag@PMoS2) were synthesized by in situ reduction, then a composite polymer scaffold (Ag@PMoS2/PGA) with sustained antitumor and antibacterial activity was successfully constructed by selective laser sintering technique. In the Ag@PMoS2 nanostructures, silver nanoparticles (Ag NPs) were sandwiched between adjacent MoS2 nanosheets (MoS2 NSs), which restrained the restacking of the MoS2 NSs. In addition, the MoS2 NSs acted as steric hindrance layers, which prevented the aggregation of Ag NPs. More importantly, MoS2 NSs can provide a barrier layer for Ag NPs, hindering Ag NPs from reacting with the external solution to prevent its quick release. The results showed that Ag@PMoS2/PGA scaffolds have stronger photothermal effect and antitumor function. Meanwhile, the Ag@PMoS2/PGA scaffolds also demonstrated slow control of silver ion (Ag+) release and more efficient long-term antibacterial ability. Besides, composite scaffolds have been proved to kill the MG-63 cells by inducing apoptosis and inhibit bacterial proliferation by upregulating the level of bacterial reactive oxygen species. This kind of novel bifunctional implants with antitumor and antibacterial properties provides better choice for the artificial bone transplantation after primary bone tumor resection.

Selective Laser Melted Rare Earth Magnesium Alloy with High Corrosion Resistance.

Magnesium (Mg) degrades too fast in human body, which limits its orthopedic application. Single-phase Mg-based supersaturated solid solution is expected to possess high corrosion resistance. In this work, rare earth scandium (Sc) was used as alloying element to prepare Mg(Sc) solid solution powder by mechanical alloying (MA) and then shaped into implant using selective laser melting (SLM). MA utilizes powerful mechanical force to introduce numerous lattice defects, which promotes the dissolution of Sc in Mg matrix and forms supersaturated solid solution particles. Subsequently, SLM with fast heating and cooling rate maintains the original supersaturated solid solution structure. Immersion tests revealed that high Sc content significantly enhanced the corrosion resistance of Mg matrix because of the formation of protective corrosion product film, which was also proved by the electrochemical impedance spectroscopy measurements. Thereby, Mg(Sc) alloy showed a relatively low degradation rate of 0.61 mm/year. In addition, cell tests showed that the Mg(Sc) exhibited favorable biocompatibility and was suitable for medical application.

Construction of magnetic nanochains to achieve magnetic energy coupling in scaffold.

BACKGROUND: Fe3O4 nanoparticles are highly desired for constructing endogenous magnetic microenvironment in scaffold to accelerate bone regeneration due to their superior magnetism. However, their random arrangement easily leads to mutual consumption of magnetic poles, thereby weakening the magnetic stimulation effect. METHODS: In this study, magnetic nanochains are synthesized by magnetic-field-guided interface co-assembly of Fe3O4 nanoparticles. In detail, multiple Fe3O4 nanoparticles are aligned along the direction of magnetic force lines and are connected in series to form nanochain structures under an external magnetic field. Subsequently, the nanochain structures are covered and fixed by depositing a thin layer of silica (SiO2), and consequently forming linear magnetic nanochains (Fe3O4@SiO2). The Fe3O4@SiO2 nanochains are then incorporated into poly l-lactic acid (PLLA) scaffold prepared by selective laser sintering technology. RESULTS: The results show that the Fe3O4@SiO2 nanochains with unique core-shell structure are successfully constructed. Meanwhile, the orderly assembly of nanoparticles in the Fe3O4@SiO2 nanochains enable to form magnetic energy coupling and obtain a highly magnetic micro-field. The in vitro tests indicate that the PLLA/Fe3O4@SiO2 scaffolds exhibit superior capacity in enhancing cell activity, improving osteogenesis-related gene expressions, and inducing cell mineralization compared with PLLA and PLLA/Fe3O4 scaffolds. CONCLUSION: In short, the Fe3O4@SiO2 nanochains endow scaffolds with good magnetism and cytocompatibility, which have great potential in accelerating bone repair.

Genome-wide identification and characterization of the HD-Zip gene family and expression analysis in response to stress in Rehmannia glutinosa Libosch.

The HD-Zip family of transcription factors is unique to the plant kingdom, and play roles in modulation of plant growth and response to environmental stresses. R. glutinosa is an important Chinese medicinal material. Its yield and quality are susceptible to various stresses. The HD-Zip transcription factors is unique to the plant, and roles in modulation of plant growth and response to environmental stresses. However, there is no relevant research on the HD-ZIP of R. glutinosa. In this study, 92 HD-Zip transcription factors were identified in R. glutinosa, and denominated as RgHDZ1-RgHDZ92. Members of RgHDZ were classified into four groups (HD-ZipI-IV) based on the phylogenetic relationship of Arabidopsis HD-Zip proteins, and each group contains 38, 18, 17, and 19 members, respectively. Expression analyses of RgHDZ genes based on transcriptome data showed that the expression of these genes could be induced by the endophytic fungus of R. glutinosa. Additionally, we showed that RgHDZ genes were differentially expressed in response to drought, waterlogging, temperature, and salinity treatments. This study provides important information for different expression patterns of stress-responsive HD-Zip and may contribute to the better understanding of the different responses of plants to biotic and abiotic stresses, and provide a molecular basis for the cultivation of resistant varieties of R. glutinosa.