Tissue engineered periosteum: Fabrication of a gelatin basedtrilayer composite scaffold with biomimetic properties for enhanced bone healing.

The periosteum, a vascularized tissue membrane, is essential in bone regeneration following fractures and bone loss due to some other reasons, yet there exist several research gaps concerning its regeneration. These gaps encompass reduced cellular proliferation and bioactivity, potential toxicity, heightened stiffness of scaffold materials, unfavorable porosity, expensive materials and procedures, and suboptimal survivability or inappropriate degradation rates of the implanted materials. This research used an interdisciplinary approach by forming a new material fabricated through electrospinning for the proposed application as a layer-by-layer tissue-engineered periosteum (TEP). TEP comprises poly(ε-caprolactone) (PCL), PCL/gelatin/magnesium-doped zinc oxide (vascular layer), and gelatin/bioactive glass/COD liver oil (osteoconductive layer). These materials were selected for their diverse properties, when integrated into the scaffold formation, successfully mimic the characteristics of native periosteum. Scanning electron microscopy (SEM) was employed to confirm the trilayer structure of the scaffold and determine the average fiber diameter. In-vitro degradation and swelling studies demonstrated a uniform degradation rate that matches the typical recovery time of periosteum. The scaffold exhibited excellent mechanical properties comparable to natural periosteum. Furthermore, the sustained release kinetics of COD liver oil were observed in the trilayer scaffold. Cell culture results indicated that the three-dimensional topography of the scaffold promoted cell growth, proliferation, and attachment, confirming its non-toxicity, biocompatibility, and bioactivity. This study suggests that the fabricated scaffold holds promise as a potential artificial periosteum for treating periostitis and bone fractures.

Drug/bioactive eluting chitosan composite foams for osteochondral tissue engineering.

Joint defects associated with a variety of etiologies often extend deep into the subchondral bone leading to functional impairment and joint immobility, and it is a very challenging task to regenerate the bone-cartilage interface offering significant opportunities for biomaterial-based interventions to improve the quality of life of patients. Herein drug-/bioactive-loaded porous tissue scaffolds incorporating nano-hydroxyapatite (nHAp), chitosan (CS) and either hydroxypropyl methylcellulose (HPMC) or Bombyx mori silk fibroin (SF) are fabricated through freeze drying method as subchondral bone substitute. A combination of spectroscopy and microscopy (Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX), and X-ray fluorescence (XRF) were used to analyze the structure of the porous biomaterials. The compressive mechanical properties of these scaffolds are biomimetic of cancellous bone tissues and capable of releasing drugs/bioactives (exemplified with triamcinolone acetonide, TA, or transforming growth factor-ß1, TGF-ß1, respectively) over a period of days. Mouse preosteoblast MC3T3-E1 cells were observed to adhere and proliferate on the tissue scaffolds as confirmed by the cell attachment, live-dead assay and alamarBlue™ assay. Interestingly, RT-qPCR analysis showed that the TA downregulated inflammatory biomarkers and upregulated the bone-specific biomarkers, suggesting such tissue scaffolds have long-term potential for clinical application.

Graphene oxide reinforced silk fibroin nanocomposite as an electroactive interface for the estimation of dopamine.

The fabrication of 2D materials and polymer-based nanocomposites deposited on flexible conductive interfaces has unblocked new horizons to expedite reaction kinetics for developing highly selective and sensitive electrochemical biosensors. Herein, we developed a novel biosensing platform, comprising graphene oxide and a silk fibroin-based nanocomposite, drop-cast on a carbon cloth electrode. The fabricated interface was expected to be a robust and miniaturized sensing platform for precise detection of dopamine (DA). Characterization was performed by SEM, EDX, FTIR, XRD, UV-visible spectroscopy, contact angle measurement, fluorescence spectroscopy, particle size, and zeta potential analysis. CV, EIS, DPV, and chronoamperometry demonstrated the superior electrochemical properties of the working interface and revealed its enhanced active surface area, increased conductivity, and accelerated electron transfer rate. The designed interface exhibited low LoD (0.41 µM), admirable stability, good sensitivity (2.46 µA µM-1 cm-2), wide linearity ranging from 100-900 µM, excellent reproducibility, and superb selectivity against dopamine even in the presence of possible interfering analytes. These findings endorse the feasibility of the practical execution of such an integrated system in real sample analysis.

Electrospun Antibacterial Composites for Cartilage Tissue Engineering.

Implantation of biomaterials capable of the controlled release of antibacterials during articular cartilage repair may prevent postoperative infections. Herein, biomaterials are prepared with biomimetic architectures (nonwoven mats of fibers) via electrospinning that are composed of poly(ɛ-caprolactone), poly(lactic acid), and Bombyx mori silk fibroin (with varying ratios) and, optionally, an antibiotic drug (cefixime trihydrate). The composition, morphology, and mechanical properties of the nanofibrous mats are characterized using scanning electron microscope, Fourier transform infrared spectroscopy, and tensile testing. The nonwoven mats have nanoscale fibers (typical diameters of 324-725 nm) and are capable of controlling the release profiles of the drug, with antibacterial activity against Gram +ve and Gram -ve bacteria (two common strains of human pathogenic bacteria, Staphylococcus aureus and Escherichia coli) under in vitro static conditions. The drug loaded nanofiber mats display cytocompatibility comparable to pure poly(ɛ-caprolactone) nanofibers when cultured with National Institutes of Health (NIH) NIH-3T3 fibroblast cell line and have long-term potential for clinical applications in the field of pharmaceutical sciences.

Smart injectable self-setting bioceramics for dental applications.

A thermo-responsive injectable bioactive glass (BAG) that has the ability to set at body temperature was prepared using pluronic F127 and hydroxypropyl methylcellulose as the carrier. The injectable composite has the advantage to fill irregular shape implantation sites and quick setting at body temperature. The structural and morphological analysis of injectable BAG before and after setting was done by using Fourier Transform Infrared spectroscopy (FTIR), and Scanning Electron Microscope (SEM). The effect of an ultrasonic scaler for a quick setting of injectable BAG was also investigated. The ultrasonic scaler sets the BAG formulation three-folds faster than at body temperature and homogenized the dispersion. The in vitro bio-adhesion was studied in the bovine tooth in both artificial saliva and deionized water for periodic time intervals, i.e., day 7, 30, 90, and 180, which confirmed the apatite layer formation. The mineral density analysis was used to differentiate the newly formed apatite with tooth apatite. In the MTT assay, the experimental material showed continuous proliferation and cell growth. This indicated that injectable hydrogel promoted cell growth, facilitated proliferation, and had no cytotoxic effect. The SEM and micro-CT results (performed after in vitro bioactivity testing) showed that the injectable BAG had the ability to regenerate dentin, hence this material has the potential to be used for dental and biomedical applications including tooth and bone regeneration in minimally invasive procedures in future.

Thyroxine-loaded chitosan/carboxymethyl cellulose/hydroxyapatite hydrogels enhance angiogenesis in in-ovo experiments.

Angiogenesis is one of the most important processes in repair and regeneration of many tissues and organs. Blood vessel formation also play a major role in repair of dental tissue(s) after ailments like periodontitis. Here we report the preparation of chitosan/carboxymethyl cellulose/hydroxyapatite based hydrogels, loaded with variable concentrations of thyroxin i.e., 0.1 µg/ml, 0.5 µg/ml and 1 µg/ml. Scanning electron microcopy images (SEM) showed all hydrogels were found to be porous and solution absorption study exhibited high swelling potential in aqueous media. FTIR spectra confirmed that the used materials did not change their chemical identity in synthesized hydrogels. The synthesized hydrogels demonstrated good bending, folding, rolling and stretching abilities. The hydrogels were tested in chick chorioallantoic membrane (CAM) assay to investigate their angiogenic potential. Hydrogel containing 0.1 µg/ml of thyroxine showed maximum neovascularization. For cytotoxicity analyses, preosteoblast cells (MC3T3-E1) were seeded on these hydrogels and materials were found to be non-toxic. These hydrogels with pro-angiogenic activity possess great potential to be used for periodontal regeneration.

Effects of Chromium-Loaded Chitosan Nanoparticles on the Intestinal Electrophysiological Indices and Glucose Transporters in Broilers.

The present study aimed to evaluate the effect of chromium-loaded chitosan nanoparticles (Cr-CNPs) on the electrophysiological indices, gene expression of glucose transporters, and tissue glycogen in broilers. A total of 200 one-day-old broilers were randomly divided into five groups, with each having five replicates (n = 8). Group A was fed a corn-soybean meal diet, while the diets of groups B, C, D, and E were supplemented with 200, 400, 800, and 1200 µg/kg of Cr as Cr-CNPs, respectively. On day 35, the jejunum was collected for electrophysiological study, gene expression of glucose transporters, and tissues glycogen determination. The basal short-circuit current and tissue conductance before the addition of glucose was the same in all groups. Following the addition of glucose, the change in short-circuit current decreased (p < 0.05) in the jejunal tissues of birds supplemented with 400 and 1200 µg Cr-CNPs compared with the control group. Gene expression of SGLT-1 and GLUT-2 remained unaffected with supplementation. The serum glucose and liver glycogen concentration decreased (p < 0.05) linearly with supplementation, while no effect was observed on muscle glycogen. In conclusion, Cr-CNPs supplementation decreases the glucose absorption and liver glycogen content, without affecting the gene expression of glucose transporters.

Bi-layered α-tocopherol acetate loaded membranes for potential wound healing and skin regeneration.

With an increase in the demand for skin regeneration products, there is a noticeable increase in developing materials that encourage, wound healing and skin regeneration. It has been reported that antioxidants play an important role in anti-inflammatory reactions, cellular proliferation and remodeling phase of wound healing. While consideration all these factors, a novel α-tocopherol acetate (vitamin E) (VE) loaded bi-layered electrospun membrane, based on lower polycaprolactone (PCL) layer and upper polylactic acid (PLA) layer, was fabricated through electrospinning. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), in-vitro degradation studies, swelling studies and VE release studies were performed to evaluate structural, physical and in-vitro behavior of membranes. Biological properties of membranes were evaluated through cell proliferation assay, cell adhesion studies, live/dead cell assay and CAM assay. SEM images showed that the average diameter of nanofibers ranged from 1 to 6 µm, while addition of VE changed the diameter and morphology of fibers. Bi-layered membranes showed significant swelling behavior through water uptake, membranes loaded with 30% VE showed 8.7% and 6.8% degradation in lysozyme and H2O2 respectively. 20% and 30% VE loaded membranes followed Korsmeyer-Peppas and first order drug release kinetics followed by non-fickian drug release kinetics. Membranes showed non-toxic behavior and supported cell proliferation via alamar blue assay, cell adhesion via SEM, cell viability via live/dead assay and wound healing by scratch assay. CAM assay showed that membranes having VE supported angiogenesis and showed significant formation of blood vessels making it suitable for skin regeneration and wound healing. Results showed that large surface area of nanofibers, porous structure and biocompatible nature are suitable for targeted clinical applications.

Development of K-doped ZnO nanoparticles encapsulated crosslinked chitosan based new membranes to stimulate angiogenesis in tissue engineered skin grafts.

Nanoparticles are well recognized for their biological applications including tissue-regeneration due to large surface area and chemical properties. In this study, K-doped zinc oxide (ZnO) nanoparticles containing porous hydrogels were synthesized via freeze gelation. The morphology and pore dimensions were studied by scanning electron microscopy (SEM). The chemical structural analysis of the synthesized hydrogels was investigated by Fourier Transform Infrared (FTIR) spectroscopy. In swelling studies, material containing ZnO nanoparticles with 2% potassium dopant concentration CLH-K2.0) showed greater degree of swelling as compared to all other materials. The degradation studied was tested in three different degradation media, i.e. phosphate buffer saline (PBS), lysozyme and hydrogen peroxide and relatively higher degradation was seen in hydrogen peroxide. The synthesized hydrogels were implanted on the chick chorioallantoic membrane (CAM) to investigate their angiogenic potential. The CLH-K2.0 hydrogel stimulated angiogenesis greater than all other materials; blood vessels were attached and grown inside this scaffold, showing its strong angiogenic potential.

Hydroxypropylmethyl cellulose (HPMC) crosslinked chitosan (CH) based scaffolds containing bioactive glass (BG) and zinc oxide (ZnO) for alveolar bone repair.

The success of a dental implant relies on the presence of an optimal alveolar ridge. The aim of this study was to fabricate HPMC crosslinked chitosan based scaffolds for alveolar bone repair. Our results indicated that HPMC crosslinked CH/BG foams presented better morphological structure (132-90.5 µm) and mechanical responses (0.451 MPa with 100 mg BG) as confirmed by SEM analysis and fatigue testing respectively. Cytotoxicity analysis at day 2, 4 and 8 demonstrated that all composites were non-toxic and supported cellular viability. Calcein AM/propidium iodide staining, Hoechst nuclear staining and cell adhesion assay reiterated that scaffolds supported pre-osteoblast cell growth, adhesion and proliferation. Differentiation potential of pre-osteoblast cells was enhanced as confirmed by alkaline phosphate assay. Furthermore, loss of S. aureus viability as low as 35% was attributed to synergistic effects of components. Overall, our results suggest that HPMC crosslinked scaffolds are potential candidates for alveolar bone repair.

Temperature-Responsive Hierarchical Polymer Brushes Switching from Bactericidal to Cell Repellency.

Unlike conventional poly(N-isopropylacrylamide) (PNIPAM)-based surfaces switching from bactericidal activity to bacterial repellency upon decreasing temperature, we developed a hierarchical polymer architecture, which could maintain bactericidal activities at room temperature while presenting bacterial repellency at physiological temperature. In this architecture, a thermoresponsive bactericidal upper layer consisting of PNIPAM-based copolymer and vancomycin (Van) moieties was built on an antifouling poly(sulfobetaine methacrylate) (PSBMA) bottom layer via sequential surface-initiated photoiniferter-mediated polymerization. At room temperature below the lower critical solution temperature (LCST), the PNIPAM-based upper layer was stretchable, facilitating contact killing of bacteria by Van. At physiological temperature (above the LCST), the PNIPAM-based layer collapsed, thus leading to the burial of Van and exposure of bottom PSBMA brushes, finally displaying notable performances in bacterial inhibition, dead bacteria detachment, and biocompatibility, simultaneously. Our strategy provides a novel pathway in the rational design of temperature-sensitive switchable surfaces, which shows great advantages in the real-world infection-resistant applications.

Chitosan/hydroxyapatite (HA)/hydroxypropylmethyl cellulose (HPMC) spongy scaffolds-synthesis and evaluation as potential alveolar bone substitutes.

Alveolar bone loss is associated with infections and its augmentation is a pre-requisite for the success of dental implants. In present study, we aim to develop and evaluate novel freeze dried doxycycline loaded chitosan (CS)/hydroxyapatite (HA) spongy scaffolds where hydroxypropylmethyl cellulose (HPMC) was added as a crosslinker. Scaffolds displayed compressive strength of 14MPa/cm3 and 0.34 as elastic response. The interconnected pore diameter was 41-273µm, favorably provided the template supporting cells and transport. An overall 10% degradation was seen after 14day's studies at pH 7.4 in PBS. Doxycycline hyclate, a frequently used drug to counter oral infections, demonstrated an initial burst release (6-8h), followed by a sustain release profile for the remaining 64h. CS/HA/HPMC scaffolds were nontoxic and promoted pre-osteoblast cell viability as seen with live/dead calcein staining after 24h where scaffolds with 10% and 25% HPMC by weight of scaffold had more viable cells. Scaffolds with 10%, 20% and 25% HPMC by weight of scaffold showed efficient cellular adhesion as seen in scanning electron microscopy images (day 8) indicating that pre-osteoblast cells were able to adhere well on the surface and into the porous structure via cytoplasmic extensions. Hoechst 33258 nuclear staining at day 2 and 8 indicated cell proliferation which was further supported byMTT assay at day 2, 4 and 8. Although all scaffolds supported pre-osteoblast cell viability, alkaline phosphatase (ALP) staining demonstrated that upon induction, differentiation was pronounced in case of scaffolds with 10% HMPC scaffolds. Conclusively, these materials having all the required mechanical and biological properties are potential candidates for alveolar bone regeneration.

Organocatalyzed Novel Synthetic Methodology for Highly Functionalized Piperidines as Potent α-Glucosidase Inhibitors.

An efficient atom-economic one-pot synthesis of highly functionalized piperidines was achieved by catalytic multicomponent reaction. A wide range of heterogeneous and homogenous catalysts were explored; however, promising results were achieved when a ß-keto-ester was reacted with selected aromatic aldehydes and anilines by using N-acetyl glycine (NAG) as catalyst. The implication of this methodology is straightforward since the products were precipitated out from the reaction solution, eliminating the need of column chromatography purifications. The synthesized piperidines were screened against α-glucosidase inhibition, which revealed that these compounds were very active inhibitors, and some of the compounds showed even better inhibition than the reference compound, at low micromolar concentrations. In silico molecular modeling was also performed to investigate the binding modes of the compounds into the active sites of the target protein.

Effect of calcium hydroxide on mechanical strength and biological properties of bioactive glass.

In this manuscript for the first time calcium hydroxide (Ca(OH)2) has been used for preparation of bioactive glass (BG-2) by co-precipitation method and compared with glass prepared using calcium nitrate tetrahydrate Ca(NO3)2·4H2O (BG-1), which is a conventional source of calcium. The new source positively affected physical, biological and mechanical properties of BG-2. The glasses were characterized by Fourier transform infrared (FTIR), X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis/Differential Scanning Calorimetry (TGA-DSC), BET surface area analysis and Knoop hardness. The results showed that BG-2 possessed relatively larger surface properties (100m(2)g(-1) surface area) as compared to BG-1 (78m(2)g(-1)), spherical morphology and crystalline phases (wollastonite and apatite) after sintering at lower than conventional temperature. These properties contribute critical role in both mechanical and biological properties of glasses. The Knoop hardness measurements revealed that BG-2 possessed much better hardness (0.43±0.06GPa at 680°C and 2.16±0.46GPa at 980°C) than BG-1 (0.24±0.01 at 680°C and 0.57±0.07GPA at 980°C) under same conditions. Alamar blue Assay and confocal microscopy revealed that BG-2 exhibited better attachment and proliferation of MG63 cells. Based on the improved biological properties of BG-2 as a consequent of novel calcium source selection, BG-2 is proposed as a bioactive ceramic for hard tissue repair and regeneration applications.

Cholinesterase Inhibitory Activities of N-Phenylthiazol-2-Amine Derivatives and their Molecular Docking Studies.

Alzheimer's disease (AD) is a type of neurodegenerative disorder which is responsible for many cognitive dysfunctions. According to the most accepted cholinergic hypothesis, cholinesterases have a major role in AD symptoms. The use of small molecules as inhibitors is one of the most useful strategies to control AD. In the present work, a series of N-phenylthiazol-2-amine derivatives was screened against acetylcholinesterase (AChE) from Electrophorus electricus and butyrylcholinesterase (BChE) from horse serum by using Ellman's method, using neostigmine and donepezil as reference drugs. Some of the assayed compounds proved to be potent inhibitors for AChE and BChE activity. N-(2,3-dimethylphenyl)thiazol-2-amine, 3j was found to be the most active inhibitor among the series with IC50 value of 0.009 ± 0.002 µM and 0.646 ± 0.012 µM against AChE and BChE, respectively. Molecular docking studies were carried out in order to better understand the ligand binding site interactions.

Novel synthesis of dihydropyrimidines for α-glucosidase inhibition to treat type 2 diabetes: in vitro biological evaluation and in silico docking.

A convenient and efficient new method has been established for the synthesis of dihydropyrimidines by inexpensive and non-toxic N-acetyl glycine (NAG) catalysed reaction of aromatic aldehydes with ethyl acetoacetate and urea/thiourea. This method is applicable for various substituted aldehydes as well as urea and thiourea. It has also been used to synthesize bicyclic oxygen-bridged pyrimidine derivatives (4d, 4j). The biological assay revealed that the majority of compounds synthesized displayed modest inhibitory activity against α-glucosidase at low micro-molar concentrations. Molecular docking studies were also performed on the most active compound, 4f (with IC50 value 112.21±0.97 µM), to show the enzyme - inhibitor interactions.

Bioactive behavior of silicon substituted calcium phosphate based bioceramics for bone regeneration.

Bone graft substitutes are widely used for bone regeneration and repair in defect sites resulting from aging, disease, trauma, or accident. With invariably increasing clinical demands, there is an urgent need to produce artificial materials, which are readily available and are capable of fast and guided skeletal repair. Calcium phosphate based bioactive ceramics are extensively utilized in bone regeneration and repair applications. Silicon is often utilized as a substituent or a dopant in these bioceramics, since it significantly enhances the ultimate properties of conventional biomaterials such as surface chemical structure, mechanical strength, bioactivity, biocompatibility, etc. This article presents an overview of the silicon substituted bioceramics, which have emerged as efficient bone replacement and bone regeneration materials. Thus, the role of silicon in enhancing the biological performance and bone forming capabilities of conventional calcium phosphate based bioceramics is identified and reviewed.

N-(2,4,6-Trimethyl-phen-yl)-1,3-thia-zol-2-amine.

In the title compound, C(12)H(14)N(2)S, the dihedral angle between the 1,3,5-trimethyl-benzene and 1,3-thia-zol-2-amine groups is 73.15 (4)°. In the crystal, inversion dimers linked by pairs of N-H⋯N hydrogen bonds generate R(2) (2)(8) loops.

Two new ballonigrin-type diterpenoids from the roots of Ballota limbata.

Two new ballonigrin type lactone diterpenoids, named ballonigrin lactone A and B, have been isolated from the roots of Ballota limbata. Structure elucidation of the isolated compounds was based on spectroscopic {IR, 1H- and 3C-NMR, and 2D-NMR (HMQC, HMBC, COSY and NOESY} and EI-MS data.

Halogen dance reactions--a review.

Halogen Dance (HD) reactions are a useful tool for synthetic chemists as they enable access to positions in aromatic and heteroaromatic systems for subsequent functionalization which are often difficult to address by other methods, hence, allowing entry to versatile scaffolds. While the method can be extremely useful, this transformation is often neglected upon designing synthetic sequences. This may be largely attributed to the lack of comprehensive reference works covering the general principles and outlining the versatility and limitations of the technique. The following review tries to present HD reactions in a clear and concise manner in order to convince more chemists of its advantages. It covers the field of HD reactions from their first observation in 1951 until the present. The important contributions leading to the elucidation of the mechanism are briefly outlined followed by a detailed mechanistic section and a discussion of factors which influence HD reactions. Finally, an overview of HD reactions on various carbocyclic and heterocyclic ring systems and its applications in the synthesis of complex compounds is given.