Healing Performance Research Articles

Self-healing properties of steel slag asphalt mixture based on experimental characterization and 3D reconstruction

Asphalt pavement is susceptible to cracking which affects its service life. And self-healing technology helps to heal micro-cracks in mixture at an early stage, but its mechanism of action at the mesoscale is still unclear. Therefore, the composition of steel slag asphalt mixture (SSAM) was designed, microwave heating performance, healing performance and road performance of SSAM were investigated by laboratory experiments. Finally, the SSAM was scanned using X-ray CT for 3D reconstruction and quantitative analyses. The results show that steel slag has obvious magnetic loss characteristics; the surface temperature of SSAM designed by composition is higher under microwave heating to obtain a better healing rate, and the road performance of SSAM meets the specification requirements. The damage-healing process mainly affects voids in SSAM, and microwave healing can reduce the fractal dimension of voids to reduce the proportion of fissures; from the healing index based on voids, self-healing can reduce the average coordination number and throat number of connected voids, thereby improving the performance of SSAM by reducing permeability. The self-healing performance of SSAM is improved through its compositional design; the mesoscopic model based on void characteristics helps to refine the theory of self-healing of asphalt mixtures under microwave heating.

Research on Fatigue-Healing Performance of Asphalt Mixture Based on the Semicircular Bending Test.

In order to study the self-healing performance of macroscopic fractures of asphalt mixtures, semicircular bending (SCB) tests were used to test 90# base asphalt mixtures, SBS (Styrene-Butadiene-Styrene) modified asphalt mixtures, and SBS + CR (Chloroprene Rubber) composite modified asphalt mixtures. The F-H-F (the asphalt mixture specimen was fatigued for a certain number of times, then healed under certain conditions, and then fatigued until destroyed) test was carried out, and the fatigue life recovery rate of the fatigue test before and after healing was defined as the healing index (HI). The gray correlation analysis method was used to judge the influence degree of influencing factors on fatigue-healing according to the correlation index. The results show the type of asphalt has the most significant influence on the healing ability of the asphalt mixture. In the case of complete healing, the fatigue-healing performance of the SBS + CR composite modified asphalt mixture was the best, followed by the SBS-modified asphalt mixture, and 90# base asphalt. When the healing temperature is close to the softening point of asphalt, the healing performance of 90# base asphalt is better when the healing temperature is low. When the healing time is longer, the healing performance is better, and there is an optimal healing time. The healing index decreased with the increase in the degree of damage. When the degree of damage is too large, the asphalt mixture will be difficult to heal.

Research on evolution process of full-layer incision of skin tissue under different laser incidences.

Considering difficulties of achieving vertical incidence of beam in different positions of skin, it is significant to study potential effects of incidence angles of laser on incisions. Surgical platform with a 1064 nm continuous fiber laser was established. Incident angle was adopted and real-time temperature fluctuations in laser operating area could be monitored. The rats were treated with laser at day 0 and day 3 after incision modeling, and H&E, Masson, Sirius Red, and Immuno-histochemical staining and enzyme-linked immunosorbent assay were adopted at day 3, 7, 14 to analyze the performance of healing. Laser with energy density of 67.54 J/mm2 can effectively accelerate wound healing in vivo, in which a laser with incident angle around 60° can effectively avoid scar hyperplasia. Therefore, the use of low energy laser with a small deflection angle has a good clinical application prospect in promoting wound healing.

Correction to: Development on bio-based concrete crack healing in soil exposures: isolation, identification, and characterization of potential bacteria and evaluation of crack healing performance

Correction to: Development on bio-based concrete crack healing in soil exposures: isolation, identification, and characterization of potential bacteria and evaluation of crack healing performance

Visual and quantitative evaluation of mechanical healing efficiency of self-healing cementitious materials through volumetric strain analysis

Self-healing is one of the research hotspots in composite materials, but evaluating healing performance has always been challenging. This study proposed a novel method to distinguish between mechanically healed cracks and unhealed cracks with non-adhesion filling by utilizing in-situ X-ray computed tomography (XCT) and digital volume correlation (DVC). The method utilized DVC to calculate volumetric strain after applying a relatively small load and then visualized the self-healing results through an algorithm that performed secondary quantitative analysis based on the volumetric strain. To demonstrate the method, the paper visualized the self-healing results of mortar samples with various microcapsule ratios, computed the self-healing rate, and conducted statistical analyses on the difference in self-healing rates between cracks of different widths and samples with different microcapsule ratios. The results demonstrated the feasibility and accuracy of the proposed method for evaluating self-healing efficiency and are consistent with observations made using scanning electron microscopy (SEM).

Cellular Mechanisms Driving the Distinct Behavior of Trichocyte Keratins in Wound Healing

AbstractTrichocyte keratins hold significant promise in accelerating wound healing. Yet it is difficult to discriminate characteristics and mechanisms from their subtypes because of the high sequence homology. Here, the distinct wound healing properties in terms of wound closure rate, epidermal regeneration and angiogenesis of 17 kinds of human hair keratins is reported. Each trichocyte keratin shows distinct behaviors with unique advantages. Amongst all, recombinant keratin (RK) 33B, RK34, RK39 and RK84 show the highest efficiency in wound closure acceleration, and RK34, RK37 and RK81 presented the strongest angiogenic performance. Furthermore, transcriptomic analysis revealed the regulatory mechanisms of trichocyte keratins in the proliferation and migration of keratinocyte and blood vessel generation. Finally, the keratins with strong re‐epithelialization and angiogenic performances significantly accelerate wound closure in a diabetic rat model established in‐house. The findings provide a panorama view of trichocyte keratin performance in wound healing and that may harbor potential for finely tailored keratin development and precision applications.

A review of the recent development in self-healing rubbers and their quantification methods

The emerging self-healing concept in rubber materials appears to be a good option for reducing rubber waste since it can enhance the longevity of the product's structure in conjunction with standard development goals to ensure sustainable consumption and efficient use of resources. Self-healing elastomers are fabricated to heal cracks and damage both at the micro and macroscopic levels to restrict failure by incorporating healing agents extrinsically or intrinsically. The major successful techniques to fabricate self-healing rubber were reviewed. The review also focuses on testing and analysis methods to understand the healing phenomena and quantification methods to measure the healing performance. The review also includes an overview of the self-healing elastomers for tyre applications.

Bioinspired, Robust, and Absorbable Cellulose Nanofibrils/Chitosan Filament with Remarkable Cytocompatibility and Wound Healing Properties.

Surgical threads are of great importance to prevent wound infection and accelerate tissue healing in surgical treatment. Cellulose nanofibrils (CNF) and chitosan (CS) are attracting increasing attention to be employed as biomedicine materials due to their nontoxicity, cytocompatibility, and biodegradability. However, a robust and absorbable cellulose-based surgical thread has not been explored. Therefore, in this work, a bioinspired CNF/CS composite thread containing 5% cationic polyacrylamide (CPAM) by the mass of CS was prepared, and the obtained CNF/CS-5C thread exhibited excellent mechanical properties and low swelling ratio in water due to the high cross-link degree. Especially, the tensile strength (1877 ± 107 MPa) of this thread was much higher than that of most reported CNF-based threads. Meanwhile, compared with commercial silk and Vicryl surgical threads, the CNF/CS-5C thread exhibited better in vitro cytocompatibility toward endothelial and fibroblast cells and lower inflammatory response in vivo to subcutaneous tissues of rats. In addition, the obtained thread could be regarded as a promising absorbable suture, which exhibited excellent wound healing performances in vivo. Therefore, the prepared absorbable thread will open a new window to prepare novel and advanced cellulose-based threads for medical applications.

In vitro investigation of wound healing performance of PVA/chitosan/silk electrospun mat loaded with deferoxamine and ciprofloxacin

Electrospinning is an advanced method used for developing wound dressings. Biopolymer-based electrospun mats have been extensively studied in tissue engineering due to their similarity to the extracellular matrix. In this study, electrospun poly(vinyl alcohol)/chitosan/silk fibroin (PChS) mat demonstrated improved mechanical properties, including tensile strength, strain at break, and Young's modulus, compared to electrospun poly(vinyl alcohol) and poly(vinyl alcohol)/chitosan mats. Similarly, the swelling capability, thermal stability, and hydrophilicity were higher in the PChS mat compared to the other ones. Hence, the PChS mat was selected for further investigation. Ciprofloxacin (CIP) was added to the PChS electrospinning solution at 5 % and 10 % concentration, and deferoxamine (DFO) was immobilized on CIP-loaded mats at 1 and 2 g/L concentration using a polydopamine linker. Evaluating mats with the dimensions of 1 × 1 cm2 showed that those containing 5 % and 10 % CIP exhibited bactericidal activity against Escherichia coli and Staphylococcus aureus. Moreover, Human dermal fibroblast cells were compatible with the fabricated mats, as confirmed by the MTT assay. Finally, drug-loaded mats had a positive effect on wound healing in a scratch test, and mats with 10 % CIP and 2 g/L DFO showed the highest effect on promoting wound healing, indicating potential for use as a wound dressing.

Preparation and characterization of polymeric cross-linked hydrogel patch for topical delivery of gentamicin

Abstract This research aimed to prepare and characterize a new type of polymeric cross-linked topical hydrogel patches for the treatment of wound infections. The free radical polymerization method was used to prepare the topical hydrogel patches by utilizing natural polymers, i.e., agarose and gelatin. These natural polymers were chemically cross-linked with monomer (acrylic acid) using ammonium persulfate as an initiator via the cross-linker N,N methylene bisacrylamide. An antibiotic, i.e., gentamicin sulfate was loaded into a designed polymeric system. The polymeric cross-linked topical hydrogel patches were made in a spherical shape, which was revealed to be stable and elastic. Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and X-ray powder diffraction investigation were used to characterize the topical hydrogel patches. Polymeric cross-linked hydrogel patches were evaluated for their sol–gel analysis, swelling studies, in vitro drug release studies against pH 5.5, 6.5, and 7.4, ex vivo drug permeation, and the deposition study on the rabbit’s skin by using a Franz diffusion cell. In addition, the skin irritation study and wound healing performance of drug-loaded topical patches were also assessed and compared to commercially available formulations. The topical hydrogel patches were found to be non-irritating to the skin for up to 72 h as determined by a Draize patch test and when compared to marketed formulations, these topical patches resulted in faster wound healing. The prepared formulation showed promising potential for the treatment of skin wound infection.

Development on bio-based concrete crack healing in soil exposures: isolation, identification, and characterization of potential bacteria and evaluation of crack healing performance

Development on bio-based concrete crack healing in soil exposures: isolation, identification, and characterization of potential bacteria and evaluation of crack healing performance

Evaluation of healing performance of blended reclaimed asphalt binders with rejuvenators based on rheological and chemical properties

Evaluation of healing performance of blended reclaimed asphalt binders with rejuvenators based on rheological and chemical properties

Application of f-FeNC@GOx cascade enzyme nanomaterials in the healing of infected wounds

AimsBacterial infection is a significant factor contributing to the deterioration of wounds, and the misuse of antibiotics has exacerbated bacterial resistance. Therefore, there is an urgent need to develop a novel antibacterial strategy to replace conventional therapies. This study aims to construct a self-activated cascade reaction nanozyme, f-FeNC@GOx, which triggers a cascade reaction in the presence of glucose. This cascade reaction generates highly toxic hydroxyl radicals (OH), thereby achieving the goal of eliminating bacteria and promoting wound healing. Material and methodsIn vitro antibacterial experiments, bacterial spread plate method, Live/Dead staining, and crystal violet staining were conducted to analyze the antibacterial ability and mechanism of f-FeNC@GOx. In vivo experiments, a mouse wound model was established, and H&E and Masson staining of wound tissues were performed to assess the antibacterial activity of the f-FeNC@GOx in vivo. Key findingsThe in vivo and in vitro experiments confirmed that f-FeNC@GOx exhibited significant antibacterial effect against both Staphylococcus aureus and Escherichia coli in the presence of glucose. Furthermore, it showed optimal wound healing performance in the wound models. SignificanceThese findings suggested that f-FeNC@GOx was a novel and effective antibacterial nanomaterial, which provided a promising antibacterial strategy using nanoenzyme based cascade reaction.

Performance evaluation concept for crack healing in bacterial concrete structure using electro mechanical impedance technique with PZT patch

Beginning and development of cracks reduce the structural performance and durability, thus a novel strategy is required to prevent such kind of occurrence. The incorporation of bacteria in the concrete system is likewise a technique to prevent the growth of the cracks by the microbial induced calcite precipitation. The Electro mechanical impedance (EMI) technique is the smart sensor-based technology that is an efficacious technique to examine the health of structures, whereas the prediction of frequency band and corresponding healing damage indicator for real-life application is the governing factor. The examination of crack healing performance in bacterial concrete by EMI technique with PZT sensors was not reported by previous studies to date. This research is motivated by the quality evaluation of crack healing in bacterial reinforced concrete beam specimens using the EMI technique with surface-bonded PZT patch and embedded concrete vibration sensor (CVS), respectively. For the fabrication of bacterial reinforced concrete beam specimen, the Gram-positive Bacillus subtilis bacteria have been used. To induce the structural damage, the three point loading was applied to the prepared reinforced concrete beam specimen. The optimal frequency band was determined which resulted in the structural condition for that the four statistical indices were investigated with various crack severities in several sub-frequency bands. The optimal frequency band was determined as 161–215 kHz. Further, the crack healing performance was investigated with a pre-evaluated optimal frequency band using the statistical damage indices. The damage indicators RMSD, MAPD, and CC were appropriate for the evaluation of damage severity; however Cov was appropriate for damage severity evaluation in lesser amounts in a sub-frequency band. The evaluated damage indicators RMSD, MAPD, Cov, and CC successfully signified the crack healing by the bacterial incorporation in concrete structures. The SEM and XRD tests were performed for the confirmation of calcite deposition at the cracks. The developed concept is resulted in significantly evaluating the healing quality of the cracks by bacterial incorporation over time.

Optimization of concrete mix designs toward the bond properties of steel reinforcement in self-healing concrete by Taguchi method

The bond of steel reinforcement in normal concrete has been extensively studied, while its bond properties in self-healing concrete has rarely been investigated because the main focus of developing self-healing concrete relies on the improved healing performance such water tightness and strength regain. In fact, the mix design of concrete will greatly affect the bonding. This study elaborates on the optimisation of mix designs for self-healing concrete toward the bond properties of steel reinforcement. The proposed healing agents were bacterial healing agent (BAC) and crystalline admixtures (CA). Mix design parameters include water-cement ratio (w/c) (0.40, 0.50 and 0.60), fine ratio (FR) (0.34, 0.44 and 0.54), and healing agent (HA) (BAC, CA and REF, without healing agent). The Taguchi method was used to formulate nine self-healing concrete mixes by considering three factors and three levels in the design. The compressive strengths of all different concrete mixtures were initially assessed and the pull-out tests on a single steel rebar embedded in concrete were performed in three different states of concrete (uncracked, cracked and healed). The sizes of the cracks were varied and three groups were identified: cracks with a width of 200-300, 300–400 and 400-500 μm. Water immersion was selected as the healing regime with two healing periods lasting 28 and 112 days. The Taguchi analysis and in-depth statistical evaluations were performed for optimisation purpose. Results showed that the compressive strength considerably increased as lowering the w/c, increasing the FR and incorporating the healing agents. The bond of steel reinforcement with the concrete matrix in the uncracked state improved after the BAC or CA was added into the concrete. The formation of cracks in the concrete significantly reduced the bond strength. After being subjected to healing, the bond strength slightly recovered. A longer healing time induced a better bond strength recovery. The phenomenon of crack closure was found at all healed specimens and the healing products were confirmed to be calcium carbonates.

The effect of oxygen and water on the provision of crack closure in bacteria-based self-healing cementitious composites

This study determined the impact of oxygen and water on the crack healing performance of bacteria-based self-healing cementitious composites (BBSHCCs). Oxygen and water are considered essential to BBSHCCs using non-ureolytic bacteria, but in practice, the availability of either, for even short periods of time, cannot be guaranteed in the immediate aftermath of a crack forming. In this study, four healing regimes, (i) daily wet-dry cycle, (ii) weekly wet-dry cycle, (iii) semi-submerged and (iv) a deposition medium, were utilised to compare the impact of oxygen and water on the performance of BBSHCCs. Furthermore, an oxygen-releasing coating (ORC) containing calcium peroxide was evaluated and used in this study to further understand the function of oxygen in bacteria-based self-healing. Results showed that bacteria-based self-healing was only effective in wet conditions that also permit oxygen to penetrate the crack. Where there was a possibility for the composite to dry, after cracking, despite being wet some of the time the self-healing was far less efficient. It was observed that an overdose of nutrients and calcium in the healing environment resulted in early rapid healing, followed at a later stage by the dissolution of the initially formed precipitates. Moreover, it was found that the ORC contributed significantly to the recovery of both crack width and water tightness of samples. These findings will aid the development of appropriate test standards for self-healing cementitious composites and for the design and implementation of such cementitious composites in practice.

Wound healing performance of electrospun PVA/70S30C bioactive glass/Ag nanoparticles mats decorated with curcumin: In vitro and in vivo investigations

Biocompatible fibrous scaffold containing polyvinyl alcohol (PVA), 70S30C bioactive glass (BG), silver (Ag) nanoparticles and curcumin (Cur) was fabricated through electrospinning method. Scanning electron microscope (SEM) and Field emission scanning electron microscopy (FESEM) were employed to investigate the morphological characteristics of the scaffolds. In addition, biodegradability, hydrophilicity, and contact angle were studied as criteria for evaluating physical properties of the scaffolds. Tensile strength was reported to be 0.971 ± 0.093 MPa. Also, the viability of fibroblasts after 7 days of cell culture was 93.58 ± 1.36 %. The antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria was illustrated using inhibition zones of 13.12 ± 0.69 and 14.21 ± 1.37 mm, respectively. Histological results revealed that tissue regeneration after 14 days of surgery was much higher for the dressing group compared to the blank group. According to the obtained results, the authors introduce the PVA-BG-Ag-Cur scaffold as a promising candidate for skin tissue engineering applications.

Self-Assembled CNF/rGO/Tannin Composite: Study of the Physicochemical and Wound Healing Properties.

In this study, a conductive composite material, based on graphene oxide (GO), nanocellulose (CNF), and tannins (TA) from pine bark, reduced using polydopamine (PDA), was developed for wound dressing. The amount of CNF and TA was varied in the composite material, and a complete characterization including SEM, FTIR, XRD, XPS, and TGA was performed. Additionally, the conductivity, mechanical properties, cytotoxicity, and in vitro wound healing of the materials were evaluated. A successful physical interaction between CNF, TA, and GO was achieved. Increasing CNF amount in the composite reduced the thermal properties, surface charge, and conductivity, but its strength, cytotoxicity, and wound healing performance were improved. The TA incorporation slightly reduced the cell viability and migration, which may be associated with the doses used and the extract's chemical composition. However, the in-vitro-obtained results demonstrated that these composite materials can be suitable for wound healing.

Development of novel self-healing strain-hardening cementitious composites (SH2CC) for dynamic cyclic loading conditions using mineral and polymer admixtures

Dynamic cyclic loading commonly encountered in engineering practice can pose great threat to the integrity and durability of concrete infrastructures. Ductile materials with enhanced self-healing performance could provide a promising solution under such conditions. This study proposes and investigates, for the first time, as self-healing SHCC (SH2CC) for dynamic reversed-cyclic (DRC) applications through incorporating a mineral substitute (MS) comprising of reactive MgO and quicklime and triethanolamine (TEA) additive in a high-volume-fly-ash matrix. Different DRC preloads were considered. Results indicated that applying 5% MS combined with 1.5% TEA additive showed optimal crack width control below 12 μm under up to 5 cycles of DRC preloading and the highest potential for mechanical strengthening of modulus of rupture, first cracking strength and flexural stiffness reaching up to 160%, 137% and 210% respectively after healing. Moreover the highest crack sealing efficiency was observed up to 88% under 14d water immersion. Microstructural analysis revealed that MS produced additional hydrates and promoted more carbonates to form in cracks during healing, while TEA effectively paused hydration under air curing but resumed the process upon water contact for massively enhancing crack healing (especially mechanical strengthening). Combining MS and TEA in SH2CC produced complementary healing products both in cracks and fibre-matrix interfaces indicating better filling and bridging of the cracks and demonstrating great potential for enhancing healing performance under aggressive loading conditions.

Characteristics and properties of asphalt mortar containing FO filler

As a preventive maintenance method, microwave self-healing is an effective method for early repairing small cracks in asphalt mixture, reducing maintenance costs and prolonging service life. However, asphalt mixtures containing aggregate-type wave-absorbing agents have a common problem of uneven heating. Asphalt mixture was prepared by partially replacing the limestone filler with ferroferric oxide (Fe3O4, FO), and the healing performance under microwave heating was studied. The rheological properties of asphalt mortars with FO and the fluidity of conventional asphalt mortars were studied by dynamic shear rheometer (DSR). Then, the magnetostatic properties and electromagnetic parameters of FO fillers were analyzed by vibrating sample magnetometer (VSM) and vector network analyzer (VNA). Finally, the semicircular bending (SCB) samples were studied by the breaking-microwave healing experiment. The results show that FO fillers have obvious ferromagnetism, and they mainly rely on magnetic loss for energy conversion. FO is beneficial to the improvement of high temperature rheological properties of asphalt mortar but not to low temperature rheological parameters; the replacement ratio of FO to limestone filler should not exceed 50%. The flow healing behavior of asphalt mortar is greatly affected by temperature, which is the fundamental reason for the self-healing of asphalt mixture. The heating efficiency of the asphalt mixture containing FO filler is significantly improved under microwave irradiation; the FO filler has a slightly negative effect on the initial strength of SCB samples but can significantly improve the healing rate after microwave.