In vitro and in vivo investigation of Argiope bruennichi spider silk-based novel biomaterial for medical use.

As a natural and biocompatible material with high strength and flexibility, spider silk is frequently used in biomedical studies. In this study, the availability of Argiope bruennichi spider silk as a surgical suture material was investigated. The effects of spider silk-based and commercial sutures, with and without Aloe vera coating, on wound healing were evaluated by a rat dorsal skin flap model, postoperatively (7th and 14th days). Biochemical, hematological, histological, immunohistochemical, small angle x-ray scattering (SAXS) analyses and mechanical tests were performed. A. bruennichi silk did not show any cytotoxic effect on the L929 cell line according to MTT and LDH assays, in vitro. The silk materials did not cause any allergic reaction, infection, or systemic effect in rats according to hematological and biochemical analyses. A. bruennichi spider silk group showed a similar healing response to commercial sutures. SAXS analysis showed that the 14th-day applications of A. bruennichi spider silk and A. vera coated commercial suture groups have comparable structural results with control group. In conclusion, A. bruennichi spider silk is biocompatible in line with the parameters examined and shows a healing response similar to the commercial sutures commonly used in the skin.

Analysis of the nano and microstructures of the cervical cementum and saliva in periodontitis: A pilot study.

OBJECTIVES: During the progression of periodontitis, the structures of the cementum and saliva are altered due to pathological changes in the environment. This study aimed to analyze the nanostructures of the cervical cementum and saliva in patients with periodontitis. METHODS: Patients with periodontitis (n = 10) and periodontally healthy controls (n = 8) were included. Single-rooted teeth with indications for extraction were obtained from individuals. The cervical-thirds of the roots were sectioned transversely to obtain 1 mm thick sections. Unstimulated whole saliva samples were collected from each individual. The nanostructures of the cementum and saliva were analyzed using small and wide-angle X-ray scattering methods. RESULTS: The mean radius and distance values of the cementum nanoparticles in the periodontitis and control groups were 368 Å and 1152 Å, and 377 Å and 1186 Å, respectively. The mean radius and distance values of the saliva nanoparticles in the periodontitis and control groups were 425 Å and 1359 Å, and 468 Å and 1452 Å, respectively. More wide-angle X-ray scattering profile peaks were observed in the cementum of the controls. Similarities were observed between the 3D profiles of the cementum and the saliva nanoparticles. CONCLUSIONS: According to the results of the present study, (i) the cementum and saliva nanoparticles were of similar size in periodontitis and healthy controls, (ii) the cementum was more crystalline according to the (002) crystallographic plane in controls, and (iii) the similarities in the 3D-profile of the cementum and saliva nanoparticles suggest some interactions between them in the sulcus/periodontal pocket at the nanolevel.

Evaluation of the protective effect on enamel demineralization of CPP-ACP paste and ROCS by vibrational spectroscopy and SAXS: An in vitro study.

The aim of this study was to investigate human dental enamel surfaces using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, and small angle X-ray scattering (SAXS) techniques concerning differences between the demineralized enamel surface and remineralized enamel surface by casein phosphopeptide amorphous calcium phosphate, Tooth mousse® (CPP-ACP) and remineralizing oral care systems (ROCS®) agents within the same tooth. For this purpose, 20 freshly extracted human maxillary central incisors without caries and defects were used. Labial surfaces of each of the teeth were divided into four sections, which were marked as follows: Group 1, normal enamel; Group 2, demineralized enamel with demineralization solution; Group 3, demineralized enamel + remineralization agent (ROCS for 10 teeth, CPP-ACP for 10 teeth); and Group 4, remineralization agent (ROCS for 10 teeth, CPP-ACP for 10 teeth). To describe the changes in tooth enamel, the phosphate group concentration within enamel was used as an indicator of the degree of mineralization. The phosphate and carbonate bands in the FTIR and Raman spectra were used to investigate the structural changes in the demineralized and remineralized enamel. Spectroscopic data were statistically analyzed in terms of CPP-ACP and ROCS using one-way analysis of variance. The carbonate content of demineralized enamel was higher than the carbonate content in the other groups (p < .03). The apatite carbonate-phosphate balance in the samples with only remineralizing agent-especially ROCS applied-changed significantly (p < .05) compared to the normal group. The average FTIR spectra of the groups were subjected to multivariate hierarchical cluster analysis (HCA) conducted with the use of the OPUS 5.5 software. Nanosized surface morphologies of the samples were compared using pair distance distributions obtained through SAXS analyses. According to the SAXS analyses, applications of CCP + ACP and ROCS agents were effective on nanostructures for all groups.

Solvent-Free UV Polymerization of n-Octadecyl Acrylate in Butyl Rubber: A Simple Way to Produce Tough and Smart Polymeric Materials at Ambient Temperature.

One of the most fascinating challenges in recent years has been to produce mechanically robust and tough polymers with smart functions such as self-healing and shape-memory behavior. Here, we report a simple and versatile strategy for the preparation of a highly tough and highly stretchable interconnected interpenetrating polymer network (c-IPN) based on butyl rubber (IIR) and poly(n-octadecyl acrylate) (PC18A) with thermally induced healing and shape-memory functions. Solvent-free UV polymerization of n-octadecyl acrylate (C18A) at 30 ± 2 °C in the presence of IIR leads to IIR/PC18A c-IPNs with sea-island or co-continuous morphologies depending on their IIR contents. The lamellar crystals with a melting temperature Tm of 51-52 °C formed by side-by-side packed octadecyl (C18) side chains are responsible for more than 99% of effective cross-links in c-IPNs, the rest being hydrophobic associations and chemical cross-links. The c-IPNs exhibit varying stiffness (9-34 MPa), stretchability (72-740%), and a significantly higher toughness (1.9-12 MJ·m-3) than their components, which can be tuned by changing the IIR/PC18A weight ratio. The properties of c-IPNs could also be tuned by incorporating a second, noncrystallizable hydrophobic monomer, namely, lauryl methacrylate (C12M), in the melt mixture. We show that the lamellar clusters acting as sacrificial bonds break at the yield point by dissipation of energy, while the ductile amorphous continuous phase keeps the structure together, leading to the toughness improvement of c-IPNs. They exhibit a two-step healing process with >90% healing efficiency with respect to the modulus and a complete shape-recovery ratio induced by heating above Tm of alkyl crystals. The temperature-induced healing occurs via a quick step where C18 bridges form between the damaged surfaces followed by a slow step controlled by the interdiffusion of C18A segments in the bulk. We also show that the strategy developed here is suitable for a variety of rubbers and n-alkyl (meth)acrylates of various side-chain lengths.

Structural studies on Demospongiae sponges from Gökçeada Island in the Northern Aegean Sea.

The Demospongiae is the largest Class in the phylum Porifera (sponges). Most sponge species in the Class Demospongiae have a skeleton of siliceous spicules and/or protein spongin or both. The first aim of this study was to perform the morphological and structural characterization of the siliceous spicules of four species belonging to Class Demospongiae (Suberites domuncula, Axinella polypoides, Axinella damicornis and Agelas oroides) collected around Gökçeada Island-Turkey (Northern Aegean Sea). The characterizations were carried out using a combination of Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM/EDX), Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Small Angle X-ray Scattering (SAXS) techniques. The sponge Chondrosia reniformis (Porifera, Demospongiae) lacks a structural skeleton of spicules or the spongin. It consists mainly of a collagenous tissue. The collagen with sponge origin is an important source in biomedical and pharmaceutical applications. The second aim of this study was to provide more information on the molecular structure of collagen of outer (ectosome) and inner (choanosome) regions of the Chondrosia reniformis using ATR-FTIR spectroscopy. Hierarchical clustering analysis (HCA) was also used for the discrimination of ATR-FTIR spectra of species.

Supramolecular Nanostructure Formation of Coassembled Amyloid Inspired Peptides.

Characterization of amyloid-like aggregates through converging approaches can yield deeper understanding of their complex self-assembly mechanisms and the nature of their strong mechanical stability, which may in turn contribute to the design of novel supramolecular peptide nanostructures as functional materials. In this study, we investigated the coassembly kinetics of oppositely charged short amyloid-inspired peptides (AIPs) into supramolecular nanostructures by using confocal fluorescence imaging of thioflavin T binding, turbidity assay and in situ small-angle X-ray scattering (SAXS) analysis. We showed that coassembly kinetics of the AIP nanostructures were consistent with nucleation-dependent amyloid-like aggregation, and aggregation behavior of the AIPs was affected by the initial monomer concentration and sonication. Moreover, SAXS analysis was performed to gain structural information on the size, shape, electron density, and internal organization of the coassembled AIP nanostructures. The scattering data of the coassembled AIP nanostructures were best fitted into to a combination of polydisperse core-shell cylinder (PCSC) and decoupling flexible cylinder (FCPR) models, and the structural parameters were estimated based on the fitting results of the scattering data. The stability of the coassembled AIP nanostructures in both fiber organization and bulk viscoelastic properties was also revealed via temperature-dependent SAXS analysis and oscillatory rheology measurements, respectively.

Micro- and nano-structural characterization of six marine sponges of the class Demospongiae.

The sponges produce their skeletal elements and silicateins are the key enzymes in this process. The mechanism underlying the formation of their silica skeleton and its structural properties are of exceptional interest for applications in technology. Micro- and nano-scale structural analysis of the six marine sponges belonging to Demospongiae [Callyspongia (Cladochalia) plicifera (Lamarck, 1814), Cervicornia cuspidifera (Lamarck, 1815), Cinachyrela sp., Niphates erecta (Duchassaing and Michelotti, 1864), Xestospongia muta (Schmidt, 1870) and Amphimedon compressa (Duchassaing and Michelotti, 1864)] were carried out by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) and Small-Angle X-ray Scattering (SAXS) techniques. The nano-structural characterizations give some informative evidence about the manner in which silica/silicatein in spicule skeletons is produced by the sponges. The sponge species were successfully discriminated using cluster analysis (HCA) based on FTIR spectra. This study demonstrates and detection of structural differences among sponges and their spicules using combined techniques.

Supramolecular GAG-like Self-Assembled Glycopeptide Nanofibers Induce Chondrogenesis and Cartilage Regeneration.

Glycosaminoglycans (GAGs) and glycoproteins are vital components of the extracellular matrix, directing cell proliferation, differentiation, and migration and tissue homeostasis. Here, we demonstrate supramolecular GAG-like glycopeptide nanofibers mimicking bioactive functions of natural hyaluronic acid molecules. Self-assembly of the glycopeptide amphiphile molecules enable organization of glucose residues in close proximity on a nanoscale structure forming a supramolecular GAG-like system. Our in vitro culture results indicated that the glycopeptide nanofibers are recognized through CD44 receptors, and promote chondrogenic differentiation of mesenchymal stem cells. We analyzed the bioactivity of GAG-like glycopeptide nanofibers in chondrogenic differentiation and injury models because hyaluronic acid is a major component of articular cartilage. Capacity of glycopeptide nanofibers on in vivo cartilage regeneration was demonstrated in microfracture treated osteochondral defect healing. The glycopeptide nanofibers act as a cell-instructive synthetic counterpart of hyaluronic acid, and they can be used in stem cell-based cartilage regeneration therapies.

Virus-like nanostructures for tuning immune response.

Synthetic vaccines utilize viral signatures to trigger immune responses. Although the immune responses raised against the biochemical signatures of viruses are well characterized, the mechanism of how they affect immune response in the context of physical signatures is not well studied. In this work, we investigated the ability of zero- and one-dimensional self-assembled peptide nanostructures carrying unmethylated CpG motifs (signature of viral DNA) for tuning immune response. These nanostructures represent the two most common viral shapes, spheres and rods. The nanofibrous structures were found to direct immune response towards Th1 phenotype, which is responsible for acting against intracellular pathogens such as viruses, to a greater extent than nanospheres and CpG ODN alone. In addition, nanofibers exhibited enhanced uptake into dendritic cells compared to nanospheres or the ODN itself. The chemical stability of the ODN against nuclease-mediated degradation was also observed to be enhanced when complexed with the peptide nanostructures. In vivo studies showed that nanofibers promoted antigen-specific IgG production over 10-fold better than CpG ODN alone. To the best of our knowledge, this is the first report showing the modulation of the nature of an immune response through the shape of the carrier system.

Self-assembled peptide amphiphile nanofibers and peg composite hydrogels as tunable ECM mimetic microenvironment.

Natural extracellular matrix (ECM) consists of complex signals interacting with each other to organize cellular behavior and responses. This sophisticated microenvironment can be mimicked by advanced materials presenting essential biochemical and physical properties in a synergistic manner. In this work, we developed a facile fabrication method for a novel nanofibrous self-assembled peptide amphiphile (PA) and poly(ethylene glycol) (PEG) composite hydrogel system with independently tunable biochemical, mechanical, and physical cues without any chemical modification of polymer backbone or additional polymer processing techniques to create synthetic ECM analogues. This approach allows noninteracting modification of multiple niche properties (e.g., bioactive ligands, stiffness, porosity), since no covalent conjugation method was used to modify PEG monomers for incorporation of bioactivity and porosity. Combining the self-assembled PA nanofibers with a chemically cross-linked polymer network simply by facile mixing followed by photopolymerization resulted in the formation of porous bioactive hydrogel systems. The resulting porous network can be functionalized with desired bioactive signaling epitopes by simply altering the amino acid sequence of the self-assembling PA molecule. In addition, the mechanical properties of the composite system can be precisely controlled by changing the PEG concentration. Therefore, nanofibrous self-assembled PA/PEG composite hydrogels reported in this work can provide new opportunities as versatile synthetic mimics of ECM with independently tunable biological and mechanical properties for tissue engineering and regenerative medicine applications. In addition, such systems could provide useful tools for investigation of how complex niche cues influence cellular behavior and tissue formation both in two-dimensional and three-dimensional platforms.

Micro- and nanoscale structures of mesiodens dentin: Combined study of FTIR and SAXS/WAXS techniques.

A mesiodens is the most common type of supernumerary tooth present in conjunction to normal dentition. A mesiodens may commonly occur in the central region of the upper or lower jaw. A mesiodens is different from normal teeth in terms of structure and shape. The aim of this study is to evaluate the micro- and nanoscale structural properties of mesiodens dentin by combined small- and wide-angle X-ray scattering (SAXS/WAXS) and Fourier transform infrared (FTIR) spectroscopy. Five freshly extracted, noncarious mesiodens and five normal dentin disks prepared from human incisor teeth were compared. Using FTIR, the phosphate-to-amide I, carbonate-to-phosphate, and carbonate-to-amide I band area ratios and the crystallinity index were quantified. SAXS/WAXS were used to study the nanostructure of mesiodens. An increase in the mineral content in the mesiodens dentin with respect to the normal group was found. Crystallinity was also significantly increased and the protein content decreased in the mesiodens dentin compared with that of normal dentin. SAXS/WAXS results revealed that mesiodens dentin has a more calcified tissue. Further, SAXS analysis revealed a nonuniform distribution of dentin fibrils in mesiodens.

A Nanocomposite Shield Constructed for Protection Against the Harmful Effects of Dental X-Rays.

OBJECTIVES: This study aimed to compare a number of new nano-composites capable of protecting the jaw from ionizing radiation. MATERIALS AND METHODS: Four different types of nano-powders [Ti, Zr (IV) oxide, Ag and Co] were mixed in a polymer matrix to create nano-composites with doping values of 8% in weight. Small-angle X-ray scattering (SAXS) analysis was performed using a HECUSSAXS system with 50 kV- 50 mA. Co nano-composites (Co-pnm) yielded the most promising values of the four nanocomposites tested in terms of X-ray absorption. Thus, 4×2 cm Co-pnm samples of different thicknesses (0.20, 0.50, 0.57 and 0.60 cm) were prepared, and SAXS analysis was performed in order to assess the effects of material thickness on xray absorption. An experimental multi part shield was constructed from Co-pnm around tooth #36 to test the effect of nanomaterial on the image quality under X-ray beam. RESULTS: Logarithmic distributions of the transmitted intensity values (I) showed that 0.20 cm Co-pnm had the highest transmission value (16.05) followed by 0.50 cm Co-pnm (15.44), 0.57 cm Co-pnm (15.07) and 0.60 cm Co-pnm (15.06). The 0.2 cm Co-pnm had an effective radius of the nano-aggregation value (77.44 Å) lower than that of the other thicknesses (0.50, 0.57 and 0.60 cm) of Co-pnm, which had similar values ranging from 66.22 to 66.34 Å. The 0.50 cm Co-pnm had the lowest Dmax value of the different thicknesses of Co-pnm tested. CONCLUSION: Co nanocomposite can be used as a protection shield for the harmful effects of dental X-ray.

Experimental and computational study on 2,2'-[(1E,2E)-hydrazine-1,2-diylidenedi(1E)eth-1-yl-1-ylidene]diphenol and its Ni(II), Pt(II), Pd(II) complexes.

2,2'-[(1E,2E)-hydrazine-1,2-diylidenedi(1E)eth-1-yl-1-ylidene]diphenol and its dimeric, binuclear Ni(II), Pd(II) and Pt(II) metal complexes were synthesized. Hydrazine derivative and its complexes were characterized by elemental analyses, LC-MS, IR, electronic spectra, (1)H and (13)C NMR spectra, conductivity and magnetic measurements. 1H and 13C shielding tensors for crystal structure were calculated with GIAO/DFT/B3LYP/6-311++G(d,p) methods in CDCl3. The vibrational band assignments were performed at B3LYP/6-311++G(d,p) theory level combined with scaled quantum mechanics force field (SQMFF) methodology. The antibacterial activities of synthesized compounds were studied against some Gram-positive and Gram-negative bacteria by using the microdilution and disk diffusion method. As the antibacterial activity results evidently show, the compound possessed a broad spectrum of activity against the tested bacteria.

Annealing of Co-Cr dental alloy: effects on nanostructure and Rockwell hardness.

PURPOSE: The aim of the study was to evaluate the effect of annealing on the nanostructure and hardness of Co-Cr metal ceramic samples that were fabricated with a direct metal laser sintering (DMLS) technique. MATERIALS AND METHODS: Five groups of Co-Cr dental alloy samples were manufactured in a rectangular form measuring 4 × 2 × 2 mm. Samples fabricated by a conventional casting technique (Group I) and prefabricated milling blanks (Group II) were examined as conventional technique groups. The DMLS samples were randomly divided into three groups as not annealed (Group III), annealed in argon atmosphere (Group IV), or annealed in oxygen atmosphere (Group V). The nanostructure was examined with the small-angle X-ray scattering method. The Rockwell hardness test was used to measure the hardness changes in each group, and the means and standard deviations were statistically analyzed by one-way ANOVA for comparison of continuous variables and Tukey's HSD test was used for post hoc analysis. P values of <.05 were accepted as statistically significant. RESULTS: The general nanostructures of the samples were composed of small spherical entities stacked atop one another in dendritic form. All groups also displayed different hardness values depending on the manufacturing technique. The annealing procedure and environment directly affected both the nanostructure and hardness of the Co-Cr alloy. Group III exhibited a non-homogeneous structure and increased hardness (48.16 ± 3.02 HRC) because the annealing process was incomplete and the inner stress was not relieved. Annealing in argon atmosphere of Group IV not only relieved the inner stresses but also decreased the hardness (27.40 ± 3.98 HRC). The results of fitting function presented that Group IV was the most homogeneous product as the minimum bilayer thickness was measured (7.11 Å). CONCLUSION: After the manufacturing with DMLS technique, annealing in argon atmosphere is an essential process for Co-Cr metal ceramic substructures. The dentists should be familiar with the materials that are used in clinic for prosthodontics treatments.

Formulation and characterization of liquid crystal systems containing azelaic acid for topical delivery.

PURPOSE: The aim of this study is to prepare and characterize azelaic acid (AzA) containing liquid crystal (LC) drug delivery systems for topical use. METHODS: Two ternary phase diagrams, containing liquid paraffin as the oil component and a mixture of two nonionic surfactants (Brij 721P and Brij 72), were constructed. Formulations chosen from the phase diagrams were characterized by polarized light microscopy, rheological analyses, differential scanning calorimetry (DSC), and small angle x-ray scattering spectroscopy. RESULTS: Polarized light microscopy proved that except the oil/water emulsion (O/W E), other formulations showed lamellar LC structure. In vitro release studies indicated that the fastest release was achieved by the Lamellar LC (LLC) and O/W E systems, whereas slower release was obtained from the emulsion containing lamellar LC (E-LLC) and distorted lamellar LC (D-LLC) systems. Results of rheological measurements both supported the results of in vitro release studies and showed that the emulsion containing the LC (E-LLC) system had the most stable structure. The formulations and their effect on stratum corneum (SC) were evaluated by DSC studies. The lamellar LC (LLC), emulsion containing lamellar liquid crystal (E-LLC), and O/W E formulations had an effect on both lipid and protein components of SC, whereas distorted lamellar liquid crystal (D-LLC) system had an effect on only the lipid components of SC. CONCLUSIONS: LLC systems could be considered promising for the topical delivery of AzA.

Synthesis and characterization of nanomagnetite particles and their polymer coated forms.

Superparamagnetic nanoparticles were prepared by coprecipitation of ferrous (Fe(2+)) and ferric (Fe(3+)) aqueous solution by a base. Nanomagnetite particles were coated with poly(St/PEG-EEM/DMAPM) and poly(St/PEG-MA/DMAPM) layer by emulsifier-free emulsion polymerization. Chemical structure of nanoparticles was characterized by both FTIR and (1)H NMR. Particle morphologies were determined by Zeta Sizer, DLS, XRD and SAXS. Structural analysis showed that after polymer coating nanomagnetite particles kept their superparamagnetic property. Besides the synthesized magnetites, polymer coated forms of these particles are more biocompatible, well dispersable and uniform. These properties make them a very strong candidate for bioengineering applications, such as bioseparation, gene transfer.

Synthesis, characterization, biological activities of dimethyltin(IV) complexes of Schiff bases with ONO-type donors.

Four different dimethyltin(IV) complexes of Schiff bases derived from 2-amino-3-hydroxypyridine and different substituted salicylaldehydes have been synthesized. The compounds, with the general formula [Me(2)Sn(2-OArCH=NC(5)H(3)NO)], where Ar=-C(6)H(3)(5-CH(3)) [Me(2)SnL(1)], -C(6)H(3)(5-NO(2)) [Me(2)SnL(2)], -C(6)H(2)(3,5-Cl(2)) [Me(2)SnL(3)], and -C(6)H(2)(3,5-I(2)) [Me(2)SnL(4)], were characterized by IR, NMR ((1)H and (13)C), mass spectroscopy and elemental analysis. Me(2)SnL(3) was also characterized by X-ray diffraction analysis and shows a fivefold C(2)NO(2) coordination with distorted square pyramidal geometry. H(3)C-Sn-CH(3) angles in the complexes were calculated using Lockhart's equations with the (1)J((117/119)Sn-(13)C) and (2)J((117/119)Sn-(1)H) values (from the (1)H-NMR and (13)C-NMR spectra). The in vitro antibacterial and antifungal activities of dimethyltin(IV) complexes were also investigated.

Mucopolysaccharidosis type I (Hurler syndrome): oral and radiographic findings and ultrastructural/chemical features of enamel and dentin.

Mucopolysaccharidosis type I (Hurler syndrome, MPS I-H) is an autosomal recessive inborn error of metabolism due to deficient alpha-L-iduronidase enzyme activity and is characterized by accumulation of incompletely degraded glycosaminoglycans that generally lead to impairment of organ and body functions. This report presents oral, dental, and radiographic findings in a boy who presented with MPS I-H. Nine of the patient's primary teeth were extracted and investigated using scanning electron microscopy, x-ray diffraction analysis, and Fourier transform infrared spectroscopy. Compared with the teeth of otherwise healthy patients, MPS I-H-affected dentin was characterized by extremely narrow dentinal tubules, whose direction followed an irregular wave-like pattern. The enamel-dentin junction was defective, as evidenced by microgaps, and the enamel displayed irregular arrangement of prisms. The additional novel observation was made that the protein structure of enamel and dentin changed in MPS I-H-affected teeth. Also, an increase was observed in the relative mineral/matrix ratio of MPS I-H-affected dentin, indicating that its protein content had decreased in comparison with normal dentin.

Crystal structure of 2,2-dimethyl succinic acid.

The title compound crystallizes triclinically in space group of P1. The C2-COOH and C3-COOH molecular groups are planar. The crystal structure is stabilized by the formation of intermolecular (O-HO) hydrogen bonds.