Antibacterial Host-Guest Intercalated LDH-Adorned Polyurethane for Accelerated Dermal Wound Healing.

Curcumin has a limited clinical application because of its extremely poor accessibility. In the present study, improved curcumin bioavailability within a castor oil polyurethane/layered double hydroxide (LDH) wound cover was achieved by preparing a curcumin p-sulfonic acid calix[4]arene (SC4A) inclusion complex. Then, it was utilized to intercalate MgAl-layered double hydroxide (MgAl-LDH) nanosheets. The incorporation of the nanostructure into a PU/Cur-SC4A-LDH film provided bacteria-killing performance against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. This finding is due to an increase in curcumin bioavailability in the PU matrix. Furthermore, all PU nanocomposites exhibited appropriate cytocompatibility based on an MTT assay. Mainly, the proliferation of L929 fibroblast cells in contact with the PU/Cur-SC4A-LDH sample was significantly further enhanced than that for other nanocomposites within 7 days. This observation can be related to the better availability of curcumin on the film's surface, which causes an improvement in the proliferation rate of cells. Regarding the histological results, the hematoxylin and eosin (H&E) images showed faster epidermal layer formation and a larger quantity of matured hair follicles for PU/Cur-SC4A-LDH-healed wounds in comparison with those for the negative control over a period of 28 days. Thus, this practical healing ability of the PU/Cur-SC4A-LDH nanocomposite makes it a promising candidate as a wound dressing film.

Polyhydroxybutyrate-starch/carbon nanotube electrospun nanocomposite: A highly potential scaffold for bone tissue engineering applications.

Blend nanofibers composed of synthetic and natural polymers with carbon nanomaterial, have a great potential for bone tissue engineering. In this study, the electrospun nanocomposite scaffolds based on polyhydroxybutyrate(PHB)-Starch-multiwalled carbon nanotubes (MWCNTs) were fabricated with different concentrations of MWCNTs including 0.5, 0.75 and 1 wt%. The synthesized scaffolds were characterized in terms of morphology, porosity, thermal and mechanical properties, biodegradation, bioactivity, and cell behavior. The effect of the developed structures on MG63 cells was determined by real-time PCR quantification of collagen type I, osteocalcin, osteopontin and osteonectin genes. Our results showed that the scaffold containing 1 wt% MWCNTs presented the lowest fiber diameter (124 ± 44 nm) with a porosity percentage above 80 % and the highest tensile strength (24.37 ± 0.22 MPa). The addition of MWCNTs has a positive effect on surface roughness and hydrophilicity. The formation of calcium phosphate sediments on the surface of the scaffolds after immersion in SBF is observed by SEM and verified by EDS and XRD analysis.MG63 cells were well cultured on the scaffold containing MWCNTs and presented more cell viability, ALP secretion, calcium deposition and gene expression compared to the scaffolds without MWCNTs. The PHB-starch-1wt.%MWCNTs scaffold can be considerable for studies of supplemental bone tissue engineering applications.

Alginate hydrogel with enhanced curcumin release through HPßCD assisted host-guest interaction.

The underprivileged pharmacodynamic action of curcumin, which arose from its low water solubility and rapid metabolism, restricts its therapeutic performance. In this study, (2-Hydroxy isopropyl)-ß-cyclodextrin (HPßCD) as a macrocycle host molecule was employed to enhance the availability and control release of curcumin by forming a host-guest inclusion complex within an in-situ forming alginate hydrogel. The formation of the inclusion complexes of curcumin with a single host molecule was characterized by FTIR, XRD, TGA, SEM, and DLS analyses. The inclusion complex of curcumin and HPßCD (HPßCD-Cur) showed a high encapsulation efficiency of 88.2 %. According to DLS results, aqueous dispersion of HPßCD-Cur exhibited a unimodal histogram after 2 and 7 days with average particles size of 207.5 and 230.6 nm, respectively. This observation could be because of the formation of an inclusion complex that effectively distributed in solution and prevented curcumin agglomeration. The prepared alginate hydrogel containing HPßCD-Cur demonstrated >87 % reduction in colonies of methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa, which significantly is higher than that for Alg/Cur (<69 %). The Alg/HPßCD-Cur hydrogel exhibited a high water uptake of 470 % after 2 h, and a curcumin cumulative release of 80 % over 72 h, with proper cytocompatibility. Consequently, it was shown that the HPßCD carrier could act as an apt host molecule that can properly encapsulate curcumin and enhance its release from the Alg/HPßCD-Cur hydrogel.

Evaluation of the effects of starch on polyhydroxybutyrate electrospun scaffolds for bone tissue engineering applications.

Efficient design for bone tissue engineering requires an understanding of the appropriate selection of biomimetic natural or synthetic materials and scalable fabrication technologies. In this research, poly (3-hydroxybutyrate) (PHB) and starch (5-15 wt%) as biological macromolecules were used to fabricate novel biomimetic scaffolds by electrospinning method. SEM results of electrospun scaffolds revealed bead-free nanofibers and three-dimensional homogenous structures with highly interconnected pores. Results of FTIR and Raman demonstrated that there were hydrogen bonds between the two polymers. The tensile strength of scaffolds was significantly improved by adding starch up to 10 wt%, from 3.05 to 15.54 MPa. In vitro degradation and hydrophilicity of the scaffolds were improved with the presence of starch. The viability and proliferation of MG-63 cells and alkaline phosphatase (ALP) activity were remarkably increased in the PHB-starch scaffolds compared to the PHB and control samples. The mineralization and calcium deposition of MG-63 cells were confirmed by alizarin red staining. It is concluded that PHB/starch electrospun scaffold could be a good candidate for bone tissue engineering applications.

A simple, green chemistry technology for fabrication of tissue-engineered scaffolds based on mussel-inspired 3D centrifugal spun.

The fabrication of 3D fibrous scaffolds with highly interconnected pores has been crucial in the development of tissue regeneration techniques. The present study describes the fabrication of 3D fibrous scaffolds by freeze-drying of polydopamine (PDA) coated centrifugal spun gelatin fibers. We wanted to combine the mussel-inspired chemistry, Maillard reaction, and the 3D microstructural advantages of centrifugal spun fibers to develop the green fibrous scaffolds at low cost, high speed, and desired mold shape. The resultant PDA-gelatin fibers exhibited a smooth 3D microstructure with a uniform formation of PDA thin ad-layer that enhanced the mechanical properties and stability of the scaffolds, and thereby decreased the degradation rate. All scaffolds showed promising properties including good dimensional and mechanical stability under wet state, optimal porosity over 94%, and high water uptake of approximately 1500%. The results of cell culture studies, further confirmed that all scaffolds exhibited appropriate biocompatibility, cell proliferation, migration, and infiltration. Particularly, the PDA-coated scaffolds showed a significant enhancement in proliferation, migration, and infiltration of HDF-GFP+ cells. These results show that a 3D porous fibrous scaffold with simplifying tunable density and desirable shape on a large scale can be readily prepared for different fields of tissue engineering applications.

A novel thymol-doped enamel bonding system: Physico-mechanical properties, bonding strength, and biological activity.

PURPOSE: Over the past decades, the preparation of antibacterial restorative dental adhesives has obtained increasing attention in order to prevent secondary caries. In the present study, a novel essential oil-based antibacterial resin adhesive was prepared and evaluated for dental applications. In this regards, thymol, which is a major phenolic component of thyme essential oil, was incorporated into methacrylate resin matrix and its effect on the physico-mechanical and biological properties of the experimental bonding agent was investigated. MATERIALS AND METHODS: Mechanical properties were evaluated via measuring flexural strength, flexural modulus and fracture toughness. Degree of conversion (DC%) of monomers was measured using FTIR spectroscopy. Viscoelastic properties of the samples were also determined by dynamic mechanical thermal analysis (DMTA). The bactericidal activity of composite specimens against Streptococcus mutans (ATCC 35668) was determined based on ASTM E 2180-07.MTT assay was performed to investigate the cytocompatibility of samples. Furthermore, the bonding strength of the adhesives was evaluated through microshear bond test on the caries-free extracted human premolar teeth and the mode of failure was investigated by scanning electron microscopy. RESULTS: Thymol-doped resin adhesive exhibited comparable degree of conversion to the control resin adhesive. The plasticizing behavior of thymol slightly decreased the flexural modulus and glass transition temperature of the thymol containing specimens, even though; it caused significant increases in fracture toughness of adhesive. The results represented appropriate antibacterial activity as well as suitable cytocompatibility. Furthermore, the thymol-doped resin adhesive showed comparable adhesive strength to the control. CONCLUSION: The thymol is extremely compatible with the methacrylate resin restorative system and completely fulfills all requirements of a good bactericidal component in construction of an ideal enamel bonding system.