Gold Nanoparticles-Modified 2D Self-Assembled Amphiphilic Peptide Nanosheets with High Biocompatibility and Photothermal Therapy Efficiency.

Amphiphilic peptides have garnered significant attention due to their highly designable and self-assembling behaviors. Self-assembled peptides hold excellent potential in various fields such as biosensing, environmental monitoring, and drug delivery, owing to their remarkable biological, physical, and chemical properties. While nanomaterials formed by peptide self-assembly have found widespread use in biomedical applications, the development of 2D peptide nanosheets based on the self-assembly of amphiphilic peptides remains challenging in terms of rational design and morphology modulation. In this study, rationally designed amphiphilic peptide molecules are self-assembled into peptide nanosheets (PNS) under specific conditions to encapsulate gold nanoparticles (AuNPs), resulting in the formation of AuNPs/PNS hybrid materials with high photothermal conversion efficiency. The findings demonstrate that 2D PNS enhances the overall photothermal therapy effect of the nanohybrid materials due to their larger hosting area for AuNPs and higher biocompatibility. The well-designed amphiphilic peptides in this study offer insights into the structural design and functional modulation of self-assembled molecules. In addition, the constructed biomimetic-functional 2D inorganic/organic nanohybrid materials hold potential applications in biomedical engineering.

Injectable Self-Healing Antibacterial Hydrogels with Tailored Functions by Loading Peptide Nanofiber-Biomimetic Silver Nanoparticles.

Polymer hydrogels find extensive application in biomedicine, serving specific purposes such as drug delivery, biosensing, bioimaging, cancer therapy, tissue engineering, and others. In response to the growing threat of bacterial infections and the escalating resistance to conventional antibiotics, this research introduces a novel injectable, self-healing antimicrobial hydrogel comprising bioactive aldolized hyaluronic acid (AHA) and quaternized chitosan (QCS). This designed QCS/AHA hydrogel incorporates self-assembling peptide nanofibers (PNFs) and small-sized silver nanoparticles (AgNPs) for tailored functionality. The resulting hybrid QCS/AHA/PNF/AgNPs hydrogel demonstrates impressive rheological characteristics, broad-spectrum antimicrobial efficacy, and high biocompatibility. Notably, its antimicrobial effectiveness against Escherichia coli and S. aureus surpasses 99.9%, underscoring its potential for treating infectious wounds. Moreover, the rheological analysis confirms its excellent shear-thinning and self-healing properties, enabling it to conform closely to irregular wound surfaces. Furthermore, the cytotoxicity assessment reveals its compatibility with human umbilical vein endothelial cells, exhibiting no significant adverse effects. The combined attributes of this bioactive QCS/AHA/PNF/AgNPs hydrogel position it as a promising candidate for antimicrobial applications and wound healing.

Study on the Thermal Decomposition Risk of 3,7-Dinitro-1,3,5,7-tetraazabicyclo[3,3,1]nonane under Different Conditions.

Given its role as a pivotal intermediate in octogen production, the thermal safety of DPT is of paramount importance due to its significant thermal hazard. To assess the potential thermal hazard associated with its decomposition, a nonisothermal DSC experiment and an ARC test were conducted. For the acquisition of more precise thermal decomposition kinetic parameters, the impact of various crucible types on the experimental outcomes was scrutinized. The DSC results indicate that the precise thermal decomposition process of DPT, an autocatalytic decomposition material, can be accurately ascertained by using a high-pressure sealed crucible test. The authentic thermal decomposition process of DPT encompasses two critical reactions: the decomposition of DPT itself and the secondary reaction and decomposition of its byproducts. A robust thermal decomposition kinetic model was established, integrating the findings from the DSC test results. Subsequently, the risk of thermal explosion during DPT storage was simulated by using a kinetic numerical simulation approach.

Application of adaptive chaotic dung beetle optimization algorithm to near-infrared spectral model transfer.

A new transfer approach was proposed to share calibration models of the hexamethylenetetramine-acetic acid solution for studying hexamethylenetetramine concentration values across different near-infrared (NIR) spectrometers. This approach combines Savitzky-Golay first derivative (S_G_1) and orthogonal signal correction (OSC) preprocessing, along with feature variable optimization using an adaptive chaotic dung beetle optimization (ACDBO) algorithm. The ACDBO algorithm employs tent chaotic mapping and a nonlinear decreasing strategy, enhancing the balance between global and local search capabilities and increasing population diversity to address limitations observed in traditional dung beetle optimization (DBO). Validated using the CEC-2017 benchmark functions, the ACDBO algorithm demonstrated superior convergence speed, accuracy, and stability. In the context of a partial least squares (PLS) regression model for transferring hexamethylenetetramine-acetic acid solutions using NIR spectroscopy, the ACDBO algorithm excelled over alternative methods such as uninformative variable elimination, competitive adaptive reweighted sampling, cuckoo search, grey wolf optimizer, differential evolution, and DBO in efficiency, accuracy of feature variable selection, and enhancement of model predictive performance. The algorithm attained outstanding metrics, including a determination coefficient for the calibration set (Rc2) of 0.99999, a root mean square error for the calibration set (RMSEC) of 0.00195%, a determination coefficient for the validation set (Rv2) of 0.99643, a root mean squared error for the validation set (RMSEV) of 0.03818%, residual predictive deviation (RPD) of 16.72574. Compared to existing OSC, slope and bias correction (S/B), direct standardization (DS), and piecewise direct standardization (PDS) model transfer methods, the novel strategy enhances the accuracy and robustness of model predictions. It eliminates irrelevant background information about the hexamethylenetetramine concentration, thereby minimizing the spectral discrepancies across different instruments. As a result, this approach yields a determination coefficient for the prediction set (Rp2) of 0.96228, a root mean squared error for the prediction set (RMSEP) of 0.12462%, and a relative error rate (RER) of 17.62331, respectively. These figures closely follow those obtained using DS and PDS, which recorded Rp2, RMSEP, and RER values of 0.97505, 0.10135%, 21.67030, and 0.98311, 0.08339%, 26.33552, respectively. Unlike conventional methods such as OSC, S/B, DS, and PDS, this novel approach does not require the analysis of identical samples across different instruments. This characteristic significantly broadens its applicability for model transfer, which is particularly beneficial for transferring specific measurement samples.

Preparation of Spherical HMX/DMF Solvates, Spherical HMX Particles, and HMX@NTO Composites: A Way to Reduce the Sensitivity of HMX.

To reduce the sensitivity of HMX (HMX = high-melting explosive-cyclotetramethylenetetranitramine), spherical HMX/DMF (DMF = dimethylformamide) solvates, spherical HMX particles, and HMX@NTO (NTO = 1,2,4-triazol-5-one) composites are prepared by crystallization. The structure and performance of spherical HMX crystals, HMX particles, and HMX@NTO composites are characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, accelerating rate calorimetry, and mechanical sensitivity test. The results show that the space group of the spherical HMX/DMF solvate is R̅3c with the lattice parameters of a = 15.9159(4) Å, b = 15.9159(4) Å, and c = 30.5136(8) Å. The non-isothermal stability and adiabatic thermal stability of HMX/DMF solvates are similar to those of HMX particles. The non-isothermal stability of HMX@NTO composites is lower than that of NTO and HMX particles, while the adiabatic thermal stability of HMX@NTO composites is higher than that of NTO but lower than that of HMX particles. The mechanical sensitivities of spherical HMX/DMF cocrystals, spherical HMX particles, and HMX@NTO composites are lower than that of raw HMX. This study can provide some guidance for desensitizing HMX and other energetic materials.

M2 macrophage-derived exosomal miR-486-5p influences the differentiation potential of bone marrow mesenchymal stem cells and osteoporosis.

BACKGROUND: An imbalance between osteogenesis and adipogenesis in bone marrow mesenchymal stem cells (BMMSCs) can cause osteoporosis. Macrophage-derived exosomes (MD-Exos) and microRNAs (miRNAs) enriched in exosomes participate in the differentiation of BMMSCs. METHODS: Bioinformatics methods were used to analyze differentially expressed miRNAs. We cocultured M2 macrophages and BMMSCs to examine the biological function of exosomal microRNA-486-5p (miR-486-5p) on BMMSCs differentiation. Gain-of-function experiments related to osteogenesis were designed to investigate the effects of exosomes carrying miR-486-5p on an ovariectomized (OVX) mice model and the direct impact of miR-486-5p on BMMSCs. A dual luciferase experiment was performed to demonstrate the target gene of miR-486-5p. RESULTS: Bioinformatics analysis identified high expression of miRNA-486 in M2 macrophage-derived exosomes (M2D-Exos). The in vitro results demonstrated that M2 macrophage-derived exosomal miR-486-5p enhanced osteogenic capacity but inhibited the adipogenesis of BMMSCs. The direct effect of miR-486-5p on BMMSCs showed the same effects. Animal experiments revealed that exosomal miR-486-5p rescued bone loss of OVX mice. SMAD2 was characterized as a target gene of miR-486-5p. Pathway analysis showed that M2 macrophage-derived exosomal miR-486-5p stimulated osteogenic differentiation via the TGF-ß/SMAD2 signalling pathway. CONCLUSIONS: Taken together, M2 macrophage-derived exosomal miR-486-5p influences the differentiation potential of BMMSCs through the miR-486-5p/SMAD2/TGF-ß signalling pathway and osteoporosis.

Ortho-silicic Acid Plays a Protective Role in Glucocorticoid-Induced Osteoporosis via the Akt/Bad Signal Pathway In Vitro and In Vivo.

Glucocorticoid-induced osteoporosis (GIOP) has been the most common form of secondary osteoporosis. Glucocorticoids (GCs) can induce osteocyte and osteoblast apoptosis. Plenty of research has verified that silicon intake would positively affect bone. However, the effects of silicon on GIOP are not investigated. In this study, we assessed the impact of ortho-silicic acid (OSA) on Dex-induced apoptosis of osteocytes by cell apoptosis assays. The apoptosis-related genes, cleaved-caspase-3, Bcl-2, and Bax, were detected by western blotting. Then, we evaluated the possible role of OSA on osteogenesis and osteoclastogenesis with Dex using Alizarin red staining and tartrate-resistant acid phosphatase (TRAP) staining. We also detected the related genes by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and western blotting. We then established the GIOP mouse model to evaluate the potential role of OSA in vivo. We found that OSA showed no cytotoxic on osteocytes below 50 µM and prevented MLO-Y4 from Dex-induced apoptosis. We also found that OSA promoted osteogenesis and inhibited osteoclastogenesis with Dex. OSA had a protective effect on GIOP mice via the Akt signal pathway in vivo. In the end, we verified the Akt/Bad signal pathway in vitro, which showed the same results. Our finding demonstrated that OSA could protect osteocytes from apoptosis induced by GCs both in vitro and in vivo. Also, it promoted osteogenesis and inhibited osteoclastogenesis with the exitance of Dex. In conclusion, OSA has the potential value as a therapeutic agent for GIOP.

Simulation of thermal hazards risk in octogen based on non-isothermal DSC data.

To evaluate the possible thermal risks associated with the storage of octogen (HMX), non-isothermal differential scanning calorimetry (DSC) experiments were conducted in order to ascertain the kinetic model and parameters governing its thermal decomposition. DSC measurements indicate that HMX underwent a crystal transformation prior to thermal decomposition. A kinetic model for the autocatalytic thermal decomposition process was developed through the analysis of its primary exothermic peaks. Subsequently, numerical simulations were performed using the aforementioned kinetic model to assess the potential thermal explosion hazard of HMX under two distinct storage conditions. The comparison was made between the models of HMX autocatalytic decomposition temperature and thermal explosion critical temperature under two distinct storage conditions. The prediction of the influence of ambient temperature on the critical temperature of thermal explosion is conducted simultaneously. Finally, the thermal hazard parameters of HMX under different package quality are given.

Using EMG signals to assess proximity of instruments to nerve roots during robot-assisted spinal surgery.

BACKGROUND: Detecting neural threats using electromyography (EMG) has gained recognition in the field of spinal surgery. To provide an efficient approach to detect neural threats during the operation of the spinal surgery robot, an automated method based the internal connection between EMG signal and neural proximity (NP) was explored by experiments. METHODS: A NP classifier was designed to distinguish the pattern of the threats. Then, it was evaluated in rabbit models in vivo. The experiments were conducted using 20 rabbits. In each rabbit, two puncture paths were created using a surgical robot. For each path, EMG signals were recorded at series of path-points with different neural proximities, and were constructed as datasets after data cleaning and processing. The proposed NP classifier was trained and tested on the datasets. RESULTS: Classification accuracy of Path 1 and Path 2 were 99.1% and 94.0%, respectively. CONCLUSION: This feasibility study proved that EMG can be used to detect the proximity of surgical instruments to nerve roots during robot-assisted spinal surgery. As the methods of detecting neural threats for surgical robots are still scarce, we believe this work will improve the clinical performance of spinal surgery robots and help the doctors to perform surgery safely.

Exosomal MiR-199a-5p Inhibits Tumorigenesis and Angiogenesis by Targeting VEGFA in Osteosarcoma.

Background: Osteosarcoma (OS) is the most common primary bone malignancy in children and adolescents. microRNAs have been found to play a vital role in tumor angiogenesis. Here, we investigated the effects of miR-199a-5p on tumor growth and angiogenesis in osteosarcoma. Furthermore, the underlying molecular mechanisms and signaling pathways were explored. Methods: The datasets were extracted from the Gene Expression Omnibus and the differentially expressed miRNAs (DEmiRNAs) were screened out by the GEO2R online platform. The potential target genes were predicted using the miRTarBase database. The predicted target genes were further analyzed by Gene Ontology and pathway enrichment analysis and a regulatory network of DEmiRNAs and their target genes was constructed. In addition, the effects of osteosarcoma cell derived exosomal miR-199a-5p on the proliferation, migration and neovascularization of HUVECs were evaluated by conducting EdU assays, Transwell experiments and tube formation assays. A dual-luciferase reporter assay was performed to detect whether VEGFA was the direct target of miR-199a-5p. Furthermore, in vivo xenograft models were established to further investigate the intrinsic role of miR-199a-5p in osteosarcoma tumorigenesis and angiogenesis. Results: A total of 149 DE-miRNAs were screened out, including 136 upregulated miRNAs and 13 downregulated miRNAs in human osteosarcoma plasma samples compared with normal plasma samples. A total of 1313 target genes of the top three upregulated and downregulated miRNAs were predicted. In the PPI network, the top 10 hub nodes with higher degrees were identified as hub genes, such as TP53 and VEGFA. By constructing the miRNA-hub gene network, we found that most of hub genes could be potentially modulated by miR-663a, miR-199a-5p and miR-223-3p. In addition, we found that the expression level of miR-199a-5p in exosomes derived from osteosarcoma cells was remarkably higher than the osteosarcoma cells, and the exosomes derived from osteosarcoma cells were transported to HUVECs. Overexpression of miR-199a-5p could significantly inhibited HUVEC proliferation, migration and neovascularization, whereas downregulation of miR-199a-5p expression exerted the opposite effect. Moreover, the in vivo results verified that overexpression of miR-199a-5p in osteosarcoma cells could suppress the growth and angiogenesis of tumors. Conclusion: Our results demonstrated that miR-199a-5p could be transported from osteosarcoma cells to HUVECs through exosomes, subsequently targeting VEGFA and inhibiting the growth and angiogenesis of osteosarcoma. Therefore, miR-199a-5p may act as a biomarker in the diagnosis and treatment of osteosarcoma.