Self-repair Function Research Articles

Silver-infused lysine crosslinked hydrogel with oxidized regenerated cellulose for prospective advanced wound dressings

The study aimed to develop a multifunctional wound dressing with enhanced antibacterial properties and wound healing promotion. The synthesis process involved preparing oxidized regenerated cellulose (ORC) following a modified procedure, synthesizing chitosan/silver nanoparticles (CS/Ag NPs) via an in-situ reduction method, and subsequently preparing ORC/CS/Lys@Ag NPs hydrogels. Characterization techniques including FTIR, XRD, SEM, and EDS were employed to analyze functional groups, lattice structure, morphology, and elemental composition. Gelation time, swelling behavior, water retention, mechanical properties, viscosity, self-healing capacity, rheological behavior, oxygen permeability, in vitro degradation, release of Ag+, and antibacterial properties were evaluated using various experimental methods. Results indicated that the novel wound dressing has the capability to evenly distribute Ag NPs to effectively counteract bacteria. It can maintain moist conditions for 86 h, resist a sturdy mechanical pressure of 11.3 KPa, and degrade by 11.045 % ± 0.429 within 8 h. Combining its efficient gas exchange abilities, self-repairing function, and biocompatibility, almost full recovery was observed in injured mouse skin within 13 days, highlighting its promising clinical utility.

MSC secretome from amniotic fluid halts IL-1β and TNF-α inflammation via the ERK/MAPK pathway, promoting cartilage regeneration in OA in vitro.

Osteoarthritis (OA) is a degenerative disease that causes chronic pain and disability worldwide. This disease is mainly caused by IL-1β and TNF-α, which lead to cartilage degradation and inhibit the repair capacity of damaged cartilage. Recent studies have shown that amniotic fluid mesenchymal stem cells (AF-MSCs) secrete proteins that can effectively help in the treatment of cartilage damaged by OA. However, the underlying mechanism is still unclear. Therefore, the aim of this study was to investigate the effects and mechanisms behind the healing properties of the AF-MSC secretome (AFS-se) under OA conditions. This study involved growing chondrocyte progenitor cells (CPCs) and traumatized cartilage tissues in the presence of the cytokines IL-1β and TNF-α, which mimic OA conditions. AFS-se was then added to the culture medium to determine its effect on the CPCs and cartilage. Cell migration, endogenous cell outgrowth, the expression of chondrogenic and anabolic genes, and the mechanism of proteins in the NF-κB and MAPK signaling pathways were examined in this study. AFS-se inhibited the inflammatory effects of IL-1β and TNF-α by significantly reducing ERK phosphorylation in the MAPK signaling pathway and decreasing downstream proinflammatory COX2 products. The impaired CPCs recovered their ability to migrate, and endogenous CPCs in injured osteoarthritic cartilage were able to regrow in response to inflammatory stimuli. Additionally, the expression of anabolic genes such as Col I, Col II, and IGF1 was restored in defective CPCs. In conclusion, this study demonstrated that AFS-se has therapeutic effects on OA by inhibiting the inflammatory functions of IL-1β and TNF-α through protein phosphorylation in the MAPK pathway while also promoting the regenerative and self-repair functions of CPCs in traumatized cartilage.

Facile preparation of durable superhydrophobic coating with microstructure self-repairing function by spraying method

Self-healing superhydrophobic coatings have attracted tremendous attention recently, although their practical applications are severely limited by hydrophobic instability and poor structure durability. In this study, a durable superhydrophobic coating was fabricated by a rapid micro/nano structural reconstruction strategy. Carbon nanofibers (CNF) with high aspect ratio were interspersed in fluorosilicone resin (FSR) to construct a uniform network structure. By combining with temperature-responsive carnauba wax (CW) and modified fluororubber (MFR), we obtained a superhydrophobic FSR/CNF/CW/MFR coating with a water contact angle (WCA) of 157 ± 1.2° and water sliding angle (WSA) of 4.5 ± 0.4°. Under the triple synergy of polymer segment migration of FSR, temperature-responsive phase transition of CW, and elastomer rebound repair of MFR, the damaged FSR/CNF/CW/MFR coating surface was rapidly reformed to a new hierarchical micro/nanostructure with short heat treatment (less than 120 s). As a result, for a flat surface, after 1000 abrasion cycles or falling ball impact, a rich micro/nano structure was rapidly reconstructed and superhydrophobic properties were restored. The reconstructed micro/nano multistage structure could effectively capture air, which led to the repaired area exhibiting a charming silver mirror effect and excellent self-cleaning performance. Therefore, this work is expected to provide new insight into the restoration of micro/nanostructures of durable superhydrophobic coatings.

Enhanced corrosion resistance of ammonium heptamolybdate (AHM) sealed Li[sbnd]Al LDHs conversion coating on aluminum alloy

In this study, we prepared a hierarchical structured coating via a versatile two-step approach for the protection of 6N01 aluminum alloy. On the basis of as-prepared secondary alkane sulphonate (SAS) modified LiAl LDHs conversion coating (SLDH) by in-situ synthesis method, ammonium heptamolybdate (AHM) was introduced in the post-treatment to fabricate AHM@SLDH with enhanced corrosion resistance. The surface morphology, chemical composition and corrosion performance are characterized by means of scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS), etc. The hybrid coating has a persistence corrosion resistance in 3.5 wt% NaCl aqueous solution with protective efficiency of 99.64 %. As a highlight, a self-repairing function is detected in the immersion test, which is attributed to the weak oxidation function of Mo (VI). We believe that AHM@SLDH in-situ grown on aluminum substrate can provide a promising route for its corrosion prevention.

A metalized and regenerated fiber Bragg grating temperature sensor with spectral self-repair ranging from −50 ℃ to 600 ℃

In this study, we developed a metalized and regenerated fiber Bragg grating (RFBG) temperature sensor with a spectral self-repairing function, aiming to measure both high and low temperatures for aircraft engine exhausting jet. The designed sensor consists of a metal substrate with an S-shaped groove, one fiber Bragg grating (FBG), and two welded sheets connected by laser welding. The high-temperature regeneration process improves the high-temperature measurement range of the sensor. In addition, an algorithm of discrete wavelet transform and Gaussian model iteration (DWT-GMI) for solving spectral degradation at low temperatures is proposed. Simulation analyses of the spectral degradation are performed to verify the feasibility of the proposed algorithm. The simulation results show that the root mean square error (RMSE) between the repaired wavelength and the actual wavelength is 0.0436. The temperature calibration experiment is conducted for different bonding methods, including AB adhesive, tin welding, and laser welding. The linear correlation coefficient of the RFBG sensor of laser welding is 0.99919, the sensitivity is 15.64 pm/℃, and the measurement range is −50 ℃ to 600 ℃, which is larger than the other two bonding methods. The accelerated life experiment is completed to predict the service life of the designed sensor according to the Arrhenius model. The above advantages enable the designed sensor suitable for air jet temperature monitoring for aircraft engines.

Hierarchically self-reporting and self-healing photothermal responsive coatings towards smart corrosion protection

For conventional anticorrosion coatings, it is challenging to simultaneously report and repair two failure stages involving coating damage and interfacial metal corrosion. Thus, it leads to difficulties for continuous detection of coating service status, and may result in premature failure of metal-based equipment. Herein, we present a novel photothermal responsive composite epoxy system with hierarchical damage reporting and healing capabilities, which is enabled by mesoporous polydopamine nano-spheres loaded with crystal violet lactone (CVL) and phenanthroline (Phen). In our design, the coating damage is indicated by the immediately intensified fluorescent and can be rapidly closed in 90 s of NIR irradiation. Furthermore, the on-demand released corrosion probes (Phen) are able to chelate with Fe2+ ions generated from localized corrosion, producing distinct visual red color to report corrosion pits and resisting corrosion developing process. The proposed smart coatings provide a concept for achieving hierarchically self-reporting and self-repairing function of general coating defects and substrate corrosion, thus having certain potential to be applied in smart anticorrosion applications.

Design and experiment of a pneumatic self-repairing soft actuator

AbstractThis paper presents a study on the design and modeling of a novel pneumatic self-repairing soft actuator. The self-repairing soft actuator is composed of driving element, heating element, and repairing element. The driving element completes the deformation of the self-repairing soft actuator. The heating element and the repairing element complete the self-repairing function of the self-repairing soft actuator. A model used to optimize the structure is established, and the structure of the self-repairing soft actuator is determined through finite element analysis and experiment. The self-repairing time model of the soft actuator is established. The influences of different factors on the self-repairing effect and the self-repairing time are analyzed. The self-repairing scheme of the soft actuator is determined. Experiments show that the shortest time for the self-repairing soft actuator to complete the self-repairing process is 83 min. When the self-repairing soft actuator works normally, the bending angle can reach 129.8° and the bending force can reach 24.96 N. After repairing, the bending angle can reach 108.2°, and the bending force can reach 21.85 N. The repaired soft actuator can complete normal locomotion.

Physiotherapy Management To Prevent Covid-19 By Improved Physical Activity In Elderly

Coronavirus 2019 (Covid 19) is an acute respiratory syn-drome caused by the corona-2 virus (SARS-CoV-2). Meanwhile, elderly is a condition characterized by a decline in the tissue's self-repairing func-tion. This decline causes various diseases and health problems, hence, efforts are needed to improve their physical condition and health after retirement. Therefore, this study aims to reduce the impact of Covid-19 on the elderly as well as to provide an overview of the physical problems associated with the virus and its prevention measures. This is an experimental study with a pre-experimental research design in the form of a one-group pre-post-test design. The results showed a probability with a p-value of <0.05, which indicates that physiotherapy management in the elderly during Covid-19 increased their physical activity, thereby eliminating the risk of exposure to the virus. The statistical analysis results showed that there was a sig-nificant difference between the pre-test and post-test on physiotherapy management. Furthermore, physical activity had a p-value of 0.015, which indicates that the level of physical activities carried out did not change, but it served as a motivation. The fear of contracting the virus had a p-value of 0.007, which shows that information on physical activity provided by physiotherapists had no effect on their fea.

A novel self-repairing hydrophobic composite coating for anti-corrosion protection of sintered Nd-Fe-B

In this paper, a corrosion-resistant glutamic acid (Glu)-Cu-Nano-Al2O3 composite coating with both hydrophobicity and self-healing characteristics was electrodeposited on the sintered Nd-Fe-B surface. The influence of the amount of Nano-Al2O3 added in the acidic Cu2+-glutamate (Glu2−) solution on the performance of the composite coating was studied, the results show that Nano-Al2O3 inclusion can make the surface of the composite coating appear papillary particles and make the composite coating hydrophobic. By analyzing the products of the composite coating after corrosion in 3.5% NaCl solution, it is shown that the codeposition copper dihydroglutamate (CuGlu2H2) and Glu particles in the composite coating are released and dissolved in the solution with pH = 6.5 after copper corrosion, and then complexed with Cu2+produced by corrosion to form an insoluble copper glutamate (CuGlu) passive film, which was deposited on the corroded coating to achieve self-repairing function and prevent further corrosion. The hydrophobicity and self-repairing function of the composite coating ensure that the sintered Nd-Fe-B has excellent corrosion resistance.

Achieving effective antibacterial property on Ag/CoO-N photocatalytic composites

Acinetobacter baumannii (A. baumannii) was widely existed in medical wastewater and easily induced infections to threaten the human healthy. We herein reported Ag/CoO-N photocatalyst composites for effective inactivation of A. baumannii. Ag/CoO-N composites were prepared by N-doping to CoO crystal in supercritical fluid followed with photo-reduction of Ag under visible-light irradiation. N-species was incorporated in the crystal structure of CoO, on which uniform Ag nanoparticles were stably deposited. Thus, the satisfactory photocatalytic sterilization of A. baumannii irradiated by visible-light irradiation was attributed to the high capability of light trapping and the efficient separation of photo-charges. Due to photo-induced electrons as the main active species, Ag nanoparticles and CoO-N synergistically realized mineralization of cell membrane, which lead K+ ions leak from cell to crack structure of bacteria, the decrease of genetic materials, and the cripple of the self-repair function in bacteria, resulting in the final cell death.

Embedded Real-Time Implementation of Bio-Inspired Central Pattern Generator with Self-Repairing Function

Both robustness and self-repairing of the rhythmic behaviors generated by central pattern generators (CPGs) play significant roles in locomotion control. Although current CPG models have been established to mimic rhythmic outputs, the mechanisms by which the self-repairing capacities of CPG systems are formed are largely unknown. In this paper, a novel bio-inspired self-repairing CPG model (BiSRP-CPG) is proposed based on the tripartite synapse, which reveals the critical role of astrocytes in the dynamic coordination of CPGs. BiSRP-CPG is implemented on the parallel FPGA platform to simulate CPG systems on real physiological scale, in which a hardware implementation method without multiplier is utilized to break the limitation of FPGA hardware resources. The experimental results verified both the robustness and self-repairing capabilities of rhythm of BiSRP-CPG in the presence of stochastic synaptic inputs and “faulty” synapse. Under the synaptic failure rate of 20%, BiSRP-CPG suffered only 10.53% performance degradation, which was much lower than the 36.84% spike loss rate of CPG networks without astrocytes. This paper provides an insight into one of the possible self-repair mechanisms of brain rhythms which can be utilized to develop autonomously fault-tolerant electronic systems.

Exudation behavior and pinning effect of the droplet on slippery liquid-infused porous surfaces (SLIPS)

The unique self-repair function of slippery liquid-infused porous surfaces (SLIPS) exerts an important effect on maintaining the continuity and stability of lubricating film. In the self-repair process of SLIPS, the exudation of lubricant in the porous matrix is a common phenomenon. Meanwhile, the exudation behavior of lubricant in the pores is still unclear. This study established a numerical model for describing the exudation of oil droplet in micropore. The morphological evolution and flow characteristics were explored to reveal the flow mechanism of oil droplet spreading to oil film. Results show that the exudation process of lubricant on porous surface involves the rise of lubricant inside the pore, the generation, breaking and spreading of droplet on porous surface. During the rise of lubricant inside the pore, the internal pressure of the lubricant was negative. When the lubricant rose to the top edge of the pore, the contact line was pinned for the first time. And the Laplace pressure of the lubricant changed from negative to positive. Then the droplet generated and grew continuously on the porous surface. The contact line was pinned again until the droplet spread to the adjacent pore. As the apparent contact angle reached the maximum advancing angle, the droplet was depinning. Therefore, both pinning of the contact line occurred at the edge of the pore in the exudation process. Under the constant competition between the volume of droplet and the surface tension, the contact line was depinning, thus promoting the spread of the droplet into a film.

Endogenous repair theory enriches construction strategies for orthopaedic biomaterials: a narrative review.

ABSTRACTThe development of tissue engineering has led to new strategies for mitigating clinical problems; however, the design of the tissue engineering materials remains a challenge. The limited sources and inadequate function, potential risk of microbial or pathogen contamination, and high cost of cell expansion impair the efficacy and limit the application of exogenous cells in tissue engineering. However, endogenous cells in native tissues have been reported to be capable of spontaneous repair of the damaged tissue. These cells exhibit remarkable plasticity, and thus can differentiate or be reprogrammed to alter their phenotype and function after stimulation. After a comprehensive review, we found that the plasticity of these cells plays a major role in establishing the cell source in the mechanism involved in tissue regeneration. Tissue engineering materials that focus on assisting and promoting the natural self-repair function of endogenous cells may break through the limitations of exogenous seed cells and further expand the applications of tissue engineering materials in tissue repair. This review discusses the effects of endogenous cells, especially stem cells, on injured tissue repairing, and highlights the potential utilisation of endogenous repair in orthopaedic biomaterial constructions for bone, cartilage, and intervertebral disc regeneration.

Simultaneous removal of micropollutants, antibiotic resistant bacteria, and antibiotic resistance genes using graphitic carbon nitride under simulated solar irradiation

The prevalence of micropollutants (MPs) and antibiotic resistance in aquatic environments has raised increasing concern for public health and ecological security. Conventional wastewater treatment processes have limited efficiency to remove these emerging contaminants. Recently, photocatalytic processes have been proposed as a promising solution to achieve enhanced performance, but there are very few studies focusing on simultaneous removal of both chemical and biological contaminants. To test the technical feasibility of a “one-stop” photocatalytic process, we evaluated the photocatalytic performance of a urea-based graphitic carbon nitride (g-C3N4) for simultaneous removal of multiple MPs, as well as antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). After a 10 min treatment under simulated solar irradiation, five MPs including sulfamethoxazole, diclofenac, mecoprop, benzotriazole, and carbamazepine (10 µg/L each) were effectively removed from spiked MilliQ water (88% of total removal efficiency) and real wastewater effluent (83% of total removal efficiency), respectively. In addition, 6.2-log reduction (complete inactivation) and 4.3-log reduction of ARB were observed after 60 min reaction in MilliQ water and real wastewater effluent, respectively. Moreover, ARB lost their self-repair function after the treatment. Lastly, atomic force microscopy images and qPCR analysis revealed that, not only the abundance of ARB but also extracellular ARGs (e-ARGs) decreased over the treatment peroid. Experiments trapping reactive species suggested that superoxide radicals (O2•-) and holes (h+) were the major active radicals contributing to contaminants degradation. The effective treatment performance for both chemical and biological contaminants, low manufacturing costs and ease of use make g-C3N4 a promising catalyst for application in the tertiary wastewater treatment processes.

Contraction model of skeletal muscle driven by external electrical stimulation-Proposal and Identification.

Biohybrid actuators consisting of skeletal muscle and artificial lattice have unique characteristics such as self-growth and self-repair functions. As a first step for developing model-based design and model-based control methods for the biohybrid actuators, we have developed a muscle contraction model. When the stimulation voltage is applied to the muscle, the electrical charges are stored in the dihydropyridine receptor, and the calcium ions are released. According to the concentration of the ions, the contractile elements generate contraction force. We have modeled this phenomenon with three characteristics in the proposed model-electrical dynamic, physiological, and mechanical dynamic characteristics. Unlike the previous models, the proposed model was verified under the condition of tetanus and incomplete tetanus with the muscle length changed. The simulated contraction force showed good agreement with the experimentally measured contraction force generated by the gastrocnemius muscle of a toad.Clinical Relevance- Biohybrid actuators are expected as a new material for medical and assistive devices having a soft and flexible characteristic. This study provides a basic contraction model for such biohybrid actuators.

Multifunctional Hybrid Hydrogel Enhanced Antitumor Therapy through Multiple Destroying DNA Functions by a Triple-Combination Synergistic Therapy.

Brachytherapy, as an effective setting for precise cancer therapy in clinic, can lead to serious DNA damage. However, its therapeutic efficacy is always limited by the DNA self-repair property, tumor hypoxia-associated radiation resistance as well as inhomogeneous distribution of the radioactive material. Herein, a multifunctional hybrid hydrogel (131 I-hydrogel/DOX/GNPs aggregates) is developed by loading gold nanoparticle aggregates (GNPs aggregates) and DOX into a radionuclide iodine-131 (131 I) labelled polymeric hydrogels (131 I-PEG-P(Tyr)8 ) for tumor destruction by completely damaging DNA self-repair functions. This hybrid hydrogel exhibits excellent photothermal/radiolabel stability, biocompatibility, and fluorescence/photothermal /SPECT imaging properties. After local injection, the sustained releasing DOX within tumor greatly inhibits the DNA replication. Meanwhile, GNPs aggregates as a radiosensitizer and photosensitizer show a significant improvement of brachytherapeutic efficacy and cause serious DNA damage. Simultaneously, GNPs aggregates induce mild photothermal therapy under 808nm laser irradiation, which not only inhibits self-repair of the damaged DNA but also effectively relieves tumor hypoxic condition to enhance the therapeutic effects of brachytherapy, leading to a triple-synergistic destruction of DNA functions. Therefore, this study provides a highly efficient tumor synergistic therapy platform and insight into the synergistic antitumor mechanism in DNA level.

Construction of Nano Chiral Molecules and Analysis of Self-Repairing Mechanism of Coating

The anti-corrosion effect of the protective coating has an important impact on the service life of metal steel components. In order to meet the high durability requirements of the coating to the new situation, the nanocomposite coating was developed. Nanoparticles and surfactants with multiple components (e.g. C19H39NO2 and C18H29NaO3S) were added to the organic solvent (epoxy) though the precise design of the interface structure and the particle size ratio to realize the self-repair function of nanocomposite coating. Nanoparticles form encapsulation structure under the action of surfactants, it can be uniformly dispersed into the matrix and form a matrix grid distribution. On this basis, nanoparticles form self-healing functional groups with chiral reversible double bonds. The double bond can be opened quickly to realize bridged when there is a small crack in the coating, so as to repair the microcrack. The results of electrochemical test indicated that the anticorrosion effect of the new coating is better than that of the original coating, and it has a certain degree of self-repair for microcracks. After soaking in 5%NaCl solution for 24 h, the repair effect can reach 70%.

Bioinspired extremely rapid self-repairing coatings for long-life repeated features

Emerging materials capable of self-repair to damaged areas are attracting attention for environmental protection and energy reduction. Although coatings whose material elasticity physically restores surface-dents are in practical use, in the case of crack damage, they cannot perform their self-repairing function. Conversely, coatings that exhibit the capacity to repeatedly repair themselves chemically have been challenged by long repair times. Here water-induced, self-repairing coatings inspired by cephalopod self-healing mechanisms were developed that can ultra-rapidly repair surface scratches. The introduction of counter-ions into polyelectrolyte multilayers produced coatings mimicking the strong β-sheet structures, noncovalent intermolecular interactions, and consequently self-repair process in cephalopods. These features resulted in a decrease in the strong polycation–polyanion electrostatic bonds and an increase in the noncovalent polymer networks. Furthermore, counter-ion addition improved the coating’s water absorption and retention properties. The ion-trapped polymer networks facilitated expansion in the horizontal direction where a scar was present, resulting in ultrafast self-repairing rate of 92% in 1 s and 100% in 10 s. These extremely rapidly self-repairing coatings have various potential applications given knowledge acceleration via machine learning. The key technology developed here paves the way for novel insights into the construction of self-repairing materials and contributes to the development of a sustainable society.

A hybrid genetic local and global search algorithm for solving no-wait flow shop problem with bi criteria

This paper addresses the m-machine no-wait Flow Shop Scheduling with Setup Times (NW-FSSWST). Two performance measures: total flow time and makespan are considered. The objective is to find a sequence that minimizing total flow time (sum C_{j}) and makespan (C_{j}) simultaneously. A Hybrid Genetic Local and Global Search Algorithm (HGLGSA) is proposed to solve the NW-FSSWST for two performance criteria. The hybrid genetic algorithm is constructed by insert-search and self-repair algorithm with self-repair function. The proposed HGLGSA is tested on 192 benchmark problems of NW-FSSWST in the literature. A full factorial experimental design is made for determined the best parameter sets that improve the performance of the proposed algorithm. The computational results are compared with the benchmark solutions from the literature. The experimental results demonstrate the effectiveness and efficiency of the proposed HGLGSA for solving NW-FSSWST.

Self-healing coatings based on PropS-SH and pH-responsive HNT-BTA nanoparticles for inhibition of pyrite oxidation to control acid mine drainage

Aiming at the prevention and control of acid mine drainage (AMD) at the source for a long-term period, herein, we report for the first time an active passivation coating with self-healing function to protect metal sulfide minerals from oxidation. Benzotriazole (BTA) inhibitor was loaded into halloysite nanotube (HNT) under vacuum condition and encapsulated by Cu-BTA complexes stoppers, and then the PropS-SH/HNT-BTA (PSHB) coating was prepared by mixing HNT-BTA nanoparticles with γ-mercaptopropyltrimethoxysilane (PropS-SH) to inhibit pyrite oxidation. The morphology and composition of HNT nanocontainers were characterized by SEM, TEM, EDS and FTIR methods. The loading capacity of BTA in HNT-BTA lumen was determined by TGA measurements. The releasing behavior of BTA under different pH conditions was investigated by UV–vis spectrophotometer and the release mechanism of BTA from HNT-BTA lumen was validated using Ritger-Peppas model. It was found that HNT-BTA could achieve stimulus-responsive release of BTA under acidic conditions. The passivation and self-healing properties of PSHB coating were studied by electrochemical measurements, chemical leaching tests and scratch tests. The experimental results showed that the novel PSHB coating had long-term oxidation resistance and active self-repair function after damage. Meanwhile, the passivation and self-healing mechanism of the PSHB coating is also introduced. It is thought that this study is helpful to bring new ideas in the field of metal sulfide mineral passivation.