Preparation and Characterization of Nano-CaCO3/Ceresine Wax Composite Shell Microcapsules Containing E-44 Epoxy Resin for Self-Healing of Cement-Based Materials

As an intelligent material, microcapsules can efficiently self-heal internal microcracks and microdefects formed in cement-based materials during service and improve their durability. In this paper, microcapsules of nano-CaCO3/ceresine wax composite shell encapsulated with E-44 epoxy resin were prepared via the melt condensation method. The core content, compactness, particle size distribution, morphologies, chemical structure and micromechanical properties of microcapsules were characterized. The results showed that the encapsulation ability, mechanical properties and compactness of microcapsules were further improved by adding nano-CaCO3 to ceresine wax. The core content, elastic modulus, hardness and weight loss rate (60 days) of nano-CaCO3/ceresine wax composite shell microcapsules (WM2) were 80.6%, 2.02 GPA, 72.54 MPa and 1.6%, respectively. SEM showed that WM2 was regularly spherical with a rough surface and sufficient space inside the microcapsules to store the healing agent. The incorporation of WM2 to mortar can greatly improve the self-healing ability of mortar after pre-damage. After 14 days of self-healing, the compressive strength recovery rate, proportion of harmful pores and chloride ion diffusion coefficient recovery rate increased to 90.1%, 45.54% and 79.8%, respectively. In addition, WM2 also has good self-healing ability for mortar surface cracks, and cracks with initial width of less than 0.35 mm on the mortar surface can completely self-heal within 3 days.

Chemical composition and seasonal variation of the volatile oils from Siparuna guianensis Aubl. leaves collected from Monte do Carmo, Tocantins

Siparuna guianensis Aubl., known as “negramina”, “capitu”, is a small tree used for headaches, colds, fevers, as a healing agent, insect, and tick repellents. This study aimed to evaluate the chemical composition and seasonal variability of essential oils from the leaves of S. guianensis. Botanical material was collected in Monte do Carmo, Tocantins, Brazil. The powder from the leaves was submitted to hydrodistillation in a Clevenger apparatus, and the identification of the compounds was performed by GC-MS. In volatile oils, 21.32% to 55.44% of sesquiterpenes, 19.95 to 49.73% of oxygenated sesquiterpenes, 0.48 to 1.55% of oxygenated monoterpenes, 0 to 5.67% of monoterpene hydrocarbons were identified, 0 to 48.2% of other compounds. The major compounds were γ-muurolene (13.99 to 35.97%), Curzerene (7.22-19.15%), Curzerenone (7.3-18.13%), 2-undecanone (3.99- 10.63%). The presence of two clusters was verified: cluster I, discriminated by the compounds Curzerenone, β-selinene, δ-elemene, corresponding to the months with the lowest index, and cluster II, discriminated by the β-burbonene, corresponding to the months with the highest index rainfall index. Comparing the present study with data from the literature, it is concluded that S. guianensis presents great chemical variability, which can be explained by genetic factors, seasonality, light, temperature, which can alter the production of metabolites. As S. guianensis has broad therapeutic potential as an antimicrobial and promising larvicidal activity, there is a need for agronomic studies to obtain specimens that require more interesting chemical components for the pharmaceutical industry. This study is the first carried out with oils from leaves collected in Monte do Carmo, Tocantins, Brazil.

Effect of the clathrate complex of selenopyran and β-cyclodextrin on the rate of healing of a conditionally aseptic full-thickness planar wound in rats

Introduction. Selenopyran is an organic selenium compound with sharply hydrophobic properties. An increase in solubility in water (and as a consequence – and bioavailability) is possible due to the formation of inclusion complexes with cyclodextrins.Aim. The aim of this work was to study the effect of a gel containing a clathrate complex of selenopyran with β-cyclodextrin on the rate of wound healing on a model of a conditionally aseptic full-thickness planar wound in rats.Materials and methods. The object of the study was a gel containing a clathrate complex of selenopyran with β-cyclodextrin (the content of selenopyran in the gel was 0.1 %). A model of a full-thickness planar wound in sexually mature male rats was used. 20 individuals were divided into 2 groups – intact (without treatment) and experimental (received gel treatment). Efficacy was assessed by the change in wound area at 3, 5, 7, 9, 11 and 14 days after application of wound.Results and discussion. The results of the study showed that the relative area of the wounds in the treated animals by the 3rd day of the experiment was less than in the intact ones. On the fifth day of the experiment, the differences were statistically significant (57.49 ± 12.51 % in treated animals versus 85.27 ± 26.61 % in intact animals). By the 14th day of the experiment, there were practically no differences in the groups of animals.Conclusion. The results obtained indicate that when using a gel containing selenopyran in combination with β-cyclodextrin, it accelerates the transition from the inflammation phase to the proliferation phase. This is most likely due to the antioxidant properties of selenopyran. Considering the lower concentration of selenopyran in comparison with the therapeutic concentrations of other antioxidants (taurine, allantoin), it can be considered as a promising wound healing agent for further study.

Understanding the Impacts of Healing Agents on the Properties of Fresh and Hardened Self-Healing Concrete: A Review

Self-healing concrete has emerged as one of the prospective materials to be used in future constructions, substituting conventional concrete with the view of extending the service life of the structures. As a proof of concept, over the last several years, many studies have been executed on the effectiveness of the addition of self-healing agents on crack sealing and healing in mortar, while studies on the concrete level are still rather limited. In most cases, mix designs were not optimized regarding the properties of the fresh concrete mixture, properties of the hardened concrete and self-healing efficiency, meaning that the healing agent was just added on top of the normal mix (no adaptations of the concrete mix design for the introduction of healing agents). A comprehensive review has been conducted on the concrete mix design and the impact of healing agents (e.g., crystalline admixtures, bacteria, polymers and minerals, of which some are encapsulated in microcapsules or macrocapsules) on the properties of fresh and hardened concrete. Eventually, the remaining research gaps in knowledge are identified.

An Investigation of Suitable Healing Agents for Vascular-Based Self-Healing in Cementitious Materials

Self-healing cementitious materials can extend the service life of structures, improve safety during repair activities and reduce costs with minimal human intervention. Recent advances in self-healing research have shown promise for capsule-based and intrinsic healing systems. However, limited information is available regarding vascular-based self-healing mechanisms. The aim of this work is to compare different commercially available healing agents regarding their suitability in a self-healing vascular network system by examining a regain in durability and mechanical properties. The healing agents investigated include sodium silicate, two polyurethanes, two water repellent agents and an epoxy resin. Sealing efficiencies above 100% were achieved for most of the healing agents, and both polyurethanes and the epoxy resin showed high regain in strength. The results obtained from this study provide a framework for selecting a healing agent given a specific application, as a healing agent’s rheology and curing properties can affect the optimal geometry and design of a vascular network.

Evaluation of the Compatibility of Modified Encapsulated Sodium Silicate for Self-Healing of Cementitious Composites

Healing agent carriers play a significant role in defining the performance of the autonomous self-healing system. Particularly, the ability to survive during the mixing process and the release of the healing agent when cracks occur without affecting the mechanical properties of the cementitious composite. Up to now, these issues are still a concern since glass capsules are unable to survive the mixing process, while some types of microcapsules were reported to cause a decrement in strength as well as limited strength recovery. Therefore, this study was twofold, addressing the surface treatment of polystyrene (PS) capsules and the evaluation of the compatibility of the modified capsules for cement-based applications. Secondly, assessing the healing performance of modified PS capsules in cementitious composites. Furthermore, the study also evaluates the potential healing performance due to the synergic effect between the encapsulation method and the autogenous self-healing mechanism. The investigation was carried out by measuring the changes in the pH of pore solution, FTIR analysis, survival ratio, and bonding strength. For self-healing assessment, the compression cracks on the cement paste were created at an early age and the strength recovery was measured at the age of 28 and 56 days. To identify the chemical compounds responsible for the healing process, SEM-EDX tests were conducted. Moreover, the effect of silica fume (SF) on bonding strength and self-healing was also evaluated. Based on the results, the modified PS capsules by roughing approach showed promising performance in terms of survivability, bonding, and recovery. The modified PS capsule increased the strength recovery by about 12.5–15% for 100%OPC and 95%OPC + 5%SF, respectively. The finding observed that the combining of modified PS capsules and the inclusion of SF gave high strength recovery of about 20% compared to 100%OPC without capsules. Thus, the modified PS capsule has a good potential for self-healing of cementitious-based applications.

A PROPOLIS AS A HEALING AGENT FOR PULP INJURIES

As one of the natural resin materials produced by bees, propolis has been used as a traditional medicine for various diseases because of its biological and pharmacological activities. The purpose of this study was to analyze the potential of propolis as a healing agent for pulp injuries. A total of 35 journals from PubMed, Ebsco, ResearchGate, Wiley Online Library, and other international journal databases were analyzed. Propolis is very rich in active components such as flavonoids that have biological functions such as anti-inflammatory, antibacterial, antifungal and antioxidant which can act as a potential healing agent

Curcumin: Its Bioavailability and Nanoparticle Formulation: A Review

Curcumin is used as traditional Indian and Chinese medicine in order to treat various diseases as well as used as a wound healing agent. Two to five percent in turmeric is curcumin; turmeric is available in yellow colour mainly obtained from polyphenolic pigment and fat-soluble substance called as curcuminoids, mostly used in the Indian subcontinent. Various clinical trials are conducted for understanding the wide range of therapeutic uses of curcumin. According to the studies, it shows that curcumin manifests very poor oral bioavailability, and forms numerous curcumin metabolites are formed after metabolism, although the bioavailability is low but the therapeutic activity of the curcumin for the various diseases, and for treatment of the disease enhancement of bioavailability of the curcumin in the future is necessary. According to the recent study on nanocurcumin with the size less than 100 nm which is an application of polymer-based nanoparticle of curcumin. It was observed that this polymer-based nanoparticle of curcumin has similar in vitro activity as that of free curcumin in pancreatic cell lines. In in-vivo study performed with the healthy volunteers a cream containing curcuminoid loaded SLNs was topically applied over the cream containing free curcuminoid showed the improvement in efficacy. Therefore, various techniques are developing for the nanoparticulate formulations. Key words: Curcuminoids, bioavailability, nanoparticulate, nanocurcumin, polyphenolic.

Wound healing and antibacterial activities of water-soluble chitosan nanoparticles and excretion/secretion as a natural combination from medicinal maggots, Lucilia cuprina

Wounds management takes a high interest in the medical field and the addition of antimicrobial agents in an assortment of wound dressings leads to delay the wound healing. This study aimed at preparing natural combination between excretion/secretion (ES) and water-soluble chitosan nanoparticles (from Lucilia cuprina maggots) and investigating its antibacterial and wound healing activities. ES of maggots was collected, and the water-soluble chitosan nanoparticles (WSCNPs) were prepared and characterized. Antibacterial activities of combinations were evaluated against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Proteus vulgaris. ES-WSC-2 combination that contains 50% ES and 1% WSCNPs showed highest antibacterial activity against all tested bacteria compared to the other combinations. In vitro, the ES-WSC-2 combination was used to study the wound healing activity by scratch assay. The synergism between ES and WSCNPs (in ES-WSC-2 combination) accelerated the wound healing rate which suggests the use of this combination as an effective natural antibacterial and wound healing agent.