Gradient layered MXene/Fe_(3)O_(4)@CNTs/TOCNF ultrathin nanocomposite paper exhibiting effective electromagnetic shielding and multifunctionality

As wearable electronic devices are rapidly developing,there is an urgent need for lightweight,flexible,and ultrathin multifunctional electromagnetic interference(EMI)shielding materials.However,the flexible ultrathin paper that combines efficient shielding and multifunctional integration remains a considerable challenge.Here,a novel MXene/Fe_(3)O_(4)@CNTs/TOCNF(MCT,MXene=transition metal carbide/carbonitride,CNTs=carbon nanotubes,TOCNF=TEMPO-oxidized cellulose nanofiber,TEMPO=2,2,6,6-tetramethylpiperidine-1-oxyl radical)nanocomposite paper with a multilayer electromagnetic gradient structure and electromagnetic dual losses was successfully prepared by a simple filtration strategy.Benefiting from effective gradient design and adjusting the proportion of TOCNF,the composite paper(only 18μm)exhibits outstanding shielding effectiveness(SE)of 66 dB in the X-band,ultrahigh thickness-specific SE and surface-specific SE values of 3300 dB·mm-1 and 31,428 dB·cm^(2)·g^(-1)respectively.Furthermore,dehydroxylation treatment improves MCT paper's hydrophobicity,environmental stability,and mechanical strength,expanding its range of use.Excitingly,the highly efficient Joule heating properties and hydrophobicity provide MCT additional de-icing capabilities.We also simulated the electromagnetic shielding effects of MCT composite paper,which was applied in practice.This study documents an innovative and intriguing material combination,providing a simple and effective manufacturing strategy for developing EMI shielding materials.MCT paper is highly suitable for outdoor portable or wearable electronic devices and has significant application potential in humid/severe cold environments.

The use of hydrogel microspheres as cell and drug delivery carriers for bone,cartilage,and soft tissue regeneration

Bone,cartilage,and soft tissue regeneration is a complex process involving many cellular activities across various cell types.Autografts remain the“gold standard”for the regeneration of these tissues.However,the use of autografts is associated with many disadvantages,including donor scarcity,the requirement of multiple surgeries,and the risk of infection.The development of tissue engineering techniques opens new avenues for enhanced tissue regeneration.Nowadays,the expectations of tissue engineering scaffolds have gone beyond merely providing physical support for cell attachment.Ideal scaffolds should also provide biological cues to actively boost tissue regeneration.As a new type of injectable biomaterial,hydrogel microspheres have been increasingly recognised as promising therapeutic carriers for the local delivery of cells and drugs to enhance tissue regeneration.Compared to traditional tissue engineering scaffolds and bulk hydrogel,hydrogel microspheres possess distinct advantages,including less invasive delivery,larger surface area,higher transparency for visualisation,and greater flexibility for functionalisation.Herein,we review the materials characteristics of hydrogel microspheres and compare their fabrication approaches,including microfluidics,batch emulsion,electrohydrodynamic spraying,lithography,and mechanical fragmentation.Additionally,based on the different requirements for bone,cartilage,nerve,skin,and muscle tissue regeneration,we summarize the applications of hydrogel microspheres as cell and drug delivery carriers for the regeneration of these tissues.Overall,hydrogel microspheres are regarded as effective therapeutic delivery carriers to enhance tissue regeneration in regenerative medicine.However,significant effort is required before hydrogel microspheres become widely accepted as commercial products for clinical use.

Hydrophobic aerogel-modified hemostatic gauze with thermal management performance

Current hemostatic agents or dressings are not efficient under extremely hot and cold environments due to deterioration of active ingredients,water evaporation and ice crystal growth.To address these challenges,we engineered a biocompatible hemostatic system with thermoregulatory properties for harsh conditions by combining the asymmetric wetting nano-silica aerogel coated-gauze(AWNSA@G)with a layer-by-layer(LBL)structure.Our AWNSA@G was a dressing with a tunable wettability prepared by spraying the hydrophobic nano-silica aerogel onto the gauze from different distances.The hemostatic time and blood loss of the AWNSA@G were 5.1 and 6.9 times lower than normal gauze in rat’s injured femoral artery model.Moreover,the modified gauze was torn off after hemostasis without rebleeding,approximately 23.8 times of peak peeling force lower than normal gauze.For the LBL structure,consisting of the nano-silica aerogel layer and a n-octadecane phase change material layer,in both hot(70℃)and cold(-27℃)environments,exhibited dual-functional thermal management and maintained a stable internal temperature.We further verified our composite presented superior blood coagulation effect in extreme environments due to the LBL structure,the pro-coagulant properties of nano-silica aerogel and unidirectional fluid pumping of AWNSA@G.Our work,therefore,shows great hemostasis potential under normal and extreme temperature environments.

3D bioprinting for biomedical devices and tissue engineering: A review of recent trends and advances

3D printing,an additive manufacturing based technology for precise 3D construction,is currently widely employed to enhance applicability and function of cell laden scaffolds.Research on novel compatible biomaterials for bioprinting exhibiting fast crosslinking properties is an essential prerequisite toward advancing 3D printing applications in tissue engineering.Printability to improve fabrication process and cell encapsulation are two of the main factors to be considered in development of 3D bioprinting.Other important factors include but are not limited to printing fidelity,stability,crosslinking time,biocompatibility,cell encapsulation and proliferation,shear-thinning properties,and mechanical properties such as mechanical strength and elasticity.In this review,we recite recent promising advances in bioink development as well as bioprinting methods.Also,an effort has been made to include studies with diverse types of crosslinking methods such as photo,chemical and ultraviolet(UV).We also propose the challenges and future outlook of 3D bioprinting application in medical sciences and discuss the high performance bioinks.

Viscosity and degradation controlled injectable hydrogel for esophageal endoscopic submucosal dissection

Endoscopic submucosal dissection(ESD)is a common procedure to treat early and precancerous gastrointestinal lesions.Via submucosal injection,a liquid cushion is created to lift and separate the lesion and malignant part from the muscular layer where the formed indispensable space is convenient for endoscopic incision.Saline is a most common submucosal injection liquid,but the formed liquid pad lasts only a short time,and thus repeated injections increase the potential risk of adverse events.Hydrogels with high osmotic pressure and high viscosity are used as an alternate;however,with some drawbacks such as tissue damage,excessive injection resistance,and high cost.Here,we reported a nature derived hydrogel of gelatin-oxidized alginate(G-OALG).Based on the rheological analysis and compare to commercial endoscopic mucosal resection(EMR)solution(0.25%hyaluronic acid,HA),a designed G-OALG hydrogel of desired concentration and composition showed higher performances in controllable gelation and injectability,higher viscosity and more stable structures.The G-OALG gel also showed lower propulsion resistance than 0.25%HA in the injection force assessment under standard endoscopic instruments,which eased the surgical operation.In addition,the G-OALG hydrogel showed good in vivo degradability biocompatibility.By comparing the results acquired via ESD to normal saline,the G-OALG shows great histocompatibility and excellent endoscopic injectability,and enables create a longer-lasting submucosal cushion.All the features have been confirmed in the living both pig and rat models.The G-OALG could be a promising submucosal injection agent for esophageal ESD.

Bridging wounds:tissue adhesives’essential mechanisms,synthesis and characterization,bioinspired adhesives and future perspectives

Bioadhesives act as a bridge in wound closure by forming an effective interface to protect against liquid and gas leakage and aid the stoppage of bleeding.To their credit,tissue adhesives have made an indelible impact on almost all wound-related surgeries.Their unique properties include minimal damage to tissues,low chance of infection,ease of use and short wound-closure time.In contrast,classic closures,like suturing and stapling,exhibit potential additional complications with long operation times and undesirable inflammatory responses.Although tremendous progress has been made in the development of tissue adhesives,they are not yet ideal.Therefore,highlighting and summarizing existing adhesive designs and synthesis,and comparing the different products will contribute to future development.This review first provides a summary of current commercial traditional tissue adhesives.Then,based on adhesion interaction mechanisms,the tissue adhesives are categorized into three main types:adhesive patches that bind molecularly with tissue,tissuestitching adhesives based on pre-polymer or precursor solutions,and bioinspired or biomimetic tissue adhesives.Their specific adhesion mechanisms,properties and related applications are discussed.The adhesion mechanisms of commercial traditional adhesives as well as their limitations and shortcomings are also reviewed.Finally,we also discuss the future perspectives of tissue adhesives.

Synthesis of graphene oxide-quaternary ammonium nanocomposite with synergistic antibacterial activity to promote infected wound healing

Background: Bacterial infection is one of the most common complications in burn, trauma, and chronic refractory wounds and is an impediment to healing. The frequent occurrence of antimicrobial-resistant bacteria due to irrational application of antibiotics increases treatment cost and mortality. Graphene oxide (GO) has been generally reported to possess high antimicrobial activity against a wide range of bacteria in vitro. In this study, a graphene oxide-quaternary ammonium salt (GO-QAS) nanocomposite was synthesized and thoroughly investigated for synergistic antibacterial activity, underlying antibacterial mechanisms and biocompatibility in vitro and in vivo. Methods: The GO-QAS nanocomposite was synthesized through amidation reactions of carboxylic group end-capped QAS polymers with primary amine-decorated GO to achieve high QAS loading ratios on nanosheets. Next, we investigated the antibacterial activity and biocompatibility of GO-QAS in vitro and in vivo. Results: GO-QAS exhibited synergistic antibacterial activity against bacteria through not only mechanical membrane perturbation, including wrapping, bacterial membrane insertion, and bacterial membrane perforation, but also oxidative stress induction. In addition, it was found that GO-QAS could eradicate multidrug-resistant bacteria more effectively than conventional antibiotics. The in vitro and in vivo toxicity tests indicated that GO-QAS did not exhibit obvious toxicity towards mammalian cel s or organs at low concentrations. Notably, GO-QAS topically applied on infected wounds maintained highly efficient antibacterial activity and promoted infected wound healing in vivo. Conclusions: The GO-QAS nanocomposite exhibits excellent synergistic antibacterial activity and good biocompatibility both in vitro and in vivo. The antibacterial mechanisms involve both mechanical membrane perturbation and oxidative stress induction. In addition, GO-QAS accelerated the healing process of infected wounds by promoting re-epithelialization and granulation tissue formation. Overall, the results indicated that the GO-QAS nanocomposite could be applied as a promising antimicrobial agent for infected wound management and antibacterial wound dressing synthesis.

Para-amino benzoic acid doped micro-grooved carbon fibers to improve strength and biocompatibility of PLA-PEG

Para-amino benzoic acid(PABA),a folic acid related metabolite,was first introduced to fabricate micro-grooves and improve hydrophilicity over surfaces of carbon fibers(CFs).Then,engineered CFs/poly(lactic acid)-poly(ethylene glycol)(PLA-PEG) biocomposites were fabricated by a solvent casting/particulate leaching method.We found that introducing small hydrophobic PABA molecules and fabricating patterned structures would lead to benign integrated interfaces between CFs and the PLA-PEG matrix.Specifically,the compressive strength of CFs/PLA-PEG was improved from 3.98 to 5.48 MPa.In addition,the CFs/PLA-PEG biocomposites significantly accelerated the adhesion and proliferation of pre-osteoblasts with minimized cytotoxidty.By comparing the cyto-compatibility of L929 and MC_3T_3 cells cultured on different modified PLA-PEG composites,it could be concluded that PABA-CFs not only overcame the limitation of poor strength of PLA-PEG,but also improved the cell growth.These results indicate that the PABA-CFs reinforced PLA-PEG biocomposites could be a potential alternative for tissue engineering scaffolds.