Synthesis of cerium, zirconium, and copper doped zinc oxide nanoparticles as potential biomaterials for tissue engineering applications

A novel eco-friendly high throughput continuous hydrothermal flow system was used to synthesise phase pure ZnO and doped ZnO in order to explore their properties for tissue engineering applications. Cerium, zirconium, and copper were introduced as dopants during flow synthesis of ZnO nanoparticles, Zirconium doped ZnO were successfully synthesised, however secondary phases of CeO and CuO were detected in X-ray diffraction (XRD). The nanoparticles were characterised using X-ray diffraction, Brunauer-Emmett-Teller (BET), Dynamic Light scattering Measurements, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and RAMAN spectroscopy was used to evaluate physical, chemical, and structural properties. The change in BET surface area was also significant, the surface area increased from 11.35 (ZnO_2) to 26.18 (ZrZnO_5). However. In case of CeZnO_5 and CuZnO_5 was not significant 13.68 (CeZnO_5) and 12.16 (CuZnO_5) respectively. Cell metabolic activity analysis using osteoblast-like cells (MG63) and human embryonic derived mesenchymal stem cells (hES-MP) demonstrated that doped ZnO nanoparticles supported higher cell metabolic activity compared to cells grown in standard media with no nanoparticles added, or pure zinc oxide nanoparticles. The ZrZnO_5 demonstrated the highest cell metabolic activity and non-cytotoxicity over the duration of 28 days as compared to un doped or Ce or Cu incorporated nanoparticles. The current data suggests that Zirconium doping positively enhances the properties of ZnO nanoparticles by increasing the surface area and cell proliferation. Therefore, are potential additives within biomaterials or for tissue engineering applications.

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.

A novel methodology for stabilization of silver nanoparticles on cotton, nylon and cotton/nylon fabrics using chitosan and triethyl orthoformate for enhanced and elongated antibacterial performance

In the present study, the commercially available three different fabrics cotton, nylon and cotton/nylon were modified by chitosan and silver nanoparticles using a crosslinker triethyl orthoformate (TEOF). Resulted cotton‑silver (Ag-Cs-Cot), nylon‑silver (Ag-Cs-Nyl) and cotton-nylon silver (Ag-Cs-Cot-Nyl) fabrics showed significant anti-bacterial activity even after 50 washing cycles. Silver nanoparticles were prepared by reducing silver nitrate through sodium borohydride at 0 °C. In FTIR spectra the peak at near 1650 cm-1 confirmed that TEOF mediated attachment of chitosan with fabrics (due to C=N) and the stretching of secondary amine near the 3375 cm-1 indicated the silver attachment to the amine group of the chitosan. In Scanning Electron Microscope (SEM) images smooth surfaces of fabrics without any damage by modification process were observed. The antibacterial activity was Analyzed by agar diffusion and broth dilution assays against Escherichia coli and Staphylococcus aureus bacterial strains and results showed 90% bacterial inhibition against E. coli and 89% bacterial inhibition against S. aureus. For testing the antibacterial durability, the modified fabrics were washed with non-ionic detergent (10g/l) for 15 minutes under aggressive stirring (100 rpm) at room temperature. The modified fabrics retained antibacterial activity over the 50 washing cycles. Finally, the commercial potential of cotton-silver fabric was evaluated by stitching it with the socks of football players and interestingly results showed that the modified fabric on the socks showed more than 90% bacterial inhibition as compared to the plain fabric after 70 minutes of playing activity.

Chitosan-sodium percarbonate-based hydrogels with sustained oxygen release potential stimulated angiogenesis and accelerated wound healing

The prolonged hypoxic conditions hinder chronic wounds from healing and lead to severe conditions such as delayed re-epithelialization and enhanced risk of infection. Multifunctional wound dressings are highly required to address the challenges of chronic wounds. Herein, we report polyurethane-coated sodium per carbonate-loaded chitosan hydrogel (CSPUO2 ) as a multifunctional dressing. The hydrogels (Control, CSPU, and CSPUO2 ) were prepared by freeze gelation method and the developed hydrogels showed high porosity, good absorption capacity, and adequate biodegradability. The release of oxygen from the CSPUO2 hydrogel was confirmed by the increase in pH and a sustained oxygen release was observed over the period of 21 days, due to polyurethane (CSPU) coating. The CSPUO2 hydrogel exhibited around 2-fold increased angiogenic potential in CAM assay when compared with Control and CSPU dressing. CSPUO2 also showed good level of antibacterial efficacy against E. coli and S. aureus. In a full-thickness rat wound model, CSPUO2 hydrogel considerably accelerated wound healing with exceptional re-epithelialization granulation tissue formation less inflammatory cells and improved skin architecture highlighting the tremendous therapeutic potential of this hydrogel when compared with control and CSPU to treat chronic diabetic and burn wounds.

Growth of diazonium-functionalized ZnO nanoflakes on flexible carbon cloth for electrochemical sensing of acetone in the liquid phase

Simple detection of acetone is indispensable due to its health and environmental concerns. Surface-modified electrodes are promising for the detection of acetone. In the present study, the facile fabrication of ZnO nanoflakes on carbon cloth (CC) is reported. The electrode was fabricated by decorating the CC with ZnO nanoparticles (ZnO NPs), followed by the hydrothermal treatment and modification with diazonium salt using linear sweep voltammetry (LSV) forming ZnO nanoflakes (ZnO NFs) on ZnO NPs/CC. The as-prepared ZnO/CC electrode was used for the detection of acetone at room temperature using cyclic voltammetry. Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) analyses were used for the chemical and physical characterization of the CC before and after each modification step. The obtained data manifested that ZnO NFs functionalized with diazonium salt increased the roughness of the CC surface, which was advantageous to promote the interaction between CC and acetone target. The modified sensing platform showed excellent performance in terms of the wide working range (0.1-2000 ppm) and low detection limit (0.03 ppm), making it a promising and cost-effective sensor of acetone in the liquid phase.

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-β1, TGF-β1, 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.

A study of the comparative effect of cerium oxide and cerium peroxide on stimulation of angiogenesis: Design and synthesis of pro-angiogenic chitosan/collagen hydrogels

Poor angiogenesis at injury site is a major problem in chronic wounds, which could lead to limbs amputation in adverse cases. To overcome this issue, several efforts have made in literature and by our group as well to develop pro-angiogenic agents. For this purpose, metal oxides due to their oxidative potential have been studied and found very attractive agents. Cerium oxides are proven to be non-toxic and their biological studies have already proved their importance in preventing chronic inflammation, and neurological diseases among several others by modulating the intracellular reactive oxygen species. In current study, we report the synthesis and neovascularization activity of cerium oxide and cerium peroxide nanoparticles when loaded into chitosan and collagen hydrogel. The hydrogels were characterized by FTIR, SEM and XRD. The pro-angiogenic behavior of these hydrogels was studied by in-vivo CAM assay. It was found that cerium peroxide loaded material showed significantly increase in angiogenesis as compared to cerium oxide loaded materials. It was demonstrated that cerium peroxide hydrogels enhanced the angiogenic capability in CAM assay as compared to cerium oxide and hence holds good potential for chronic ulcer and burn wounds healing.

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.

Design and development of thyroxine/heparin releasing affordable cotton dressings to treat chronic wounds

This research on a thyroxine/heparin-based cotton wound dressing tests angiogenic and wound healing ability of thyroxine/heparin in a chick chorionic allantoic membrane bioassay and in skin wounds in healthy rats. Commercially available cotton dressings were simply loaded with thyroxine/heparin solutions and coated with wax. Prior to undertaking the animal study, we assessed in vitro release of thyroxine/heparin from coated and uncoated cotton dressings. Both showed more than 85% release of drug over 14 days, though the lesser release was observed in wax-coated thyroxine/heparin dressing as compared to uncoated thyroxine/heparin dressing. Testing of angiogenesis through CAM assay proved good angiogenic potential of heparin and thyroxin, but the thyroxine found more angiogenic than heparin. In animal study, full-thickness skin wounds of 20 mm diameter showed good healing in both heparin and thyroxine-treated groups. But the most striking result was seen in the thyroxine-treated group where thyroxine showed significant difference with heparin-treated group and completely healed the wounds in 23 days. Thus, the study suggest that thyroxine possesses greater angiogenic and wound healing potential than heparin, and the use of thyroxine/heparin-loaded wax-coated cotton dressing could be a cost-effective option for the management of chronic wounds.

In-depth drug delivery to tumoral soft tissues via pH responsive hydrogel

A pH responsive nanoparticle–hydrogel hybrid drug delivery system was investigated for in-depth anticancer drug delivery to solid tumours. It consists of acid susceptible polymer nanoparticles loaded in a chitosan hydrogel. The hybrid formulation was characterized by UV-visible spectroscopy, FTIR, SEM, TEM, particle size analysis, zeta potential measurement and viscosity measurement. Drug encapsulation and nanoparticle loading efficiencies were found to be 48% and 72% respectively which describes the efficient interaction of the chemical entities in this hybrid drug delivery system. The hydrogel exhibited pH responsive behaviour: minimal drug and nanoparticle release at physiological pH but an increase in viscosity under acidic conditions and fast nanoparticle and drug release. The cytotoxicity of the drug loaded hydrogel was investigated against the MCF-7 breast cancer cell line along with the drug and nanoparticles without hydrogel. The drug loaded hydrogel showed a better cytotoxic effect on MCF-7 cancer cells. Thus, drug loaded nanoparticles containing hydrogel could be a better option for maximum drug distribution in tumours.

A pH responsive nanoparticle–hydrogel hybrid drug delivery system was investigated for in-depth anticancer drug delivery to solid tumours.

Low-temperature flow-synthesis-assisted urethane-grafted zinc oxide-based dental composites: physical, mechanical, and antibacterial responses

A novel way was adopted to graft zinc oxide (ZnO) with urethane-modified dimethacrylate (UDMA) in order to utilize them as reinforcing agents in resin-based dental composites. Experimental novel composites were synthesized having UDMA-grafted and nongrafted ZnO, at a concentration of 0 wt.%, 5 wt.%, and 10 wt.%. The same concentrations of ZnO were also incorporated in Filtek Z250 XT (3 M ESPE, USA). The antibacterial behavior was evaluated against Streptococcus mutans by direct-contact test at one, three, and seven days of incubation. The compressive strength and Vickers microhardness were tested as per ISO 9917 and ISO/CD6507-1, respectively. For abrasive wear resistance, mass loss and roughness average after tooth-brushing cycles of 24,000 at custom-made tooth-brushing simulator were evaluated using noncontact profilometer. Data analysis was carried out using post hoc Tucky's test and nonparametric Kruskal-Wallis test. Direct contact test revealed that the antibacterial potential of novel and commercial composites was increased with an increase in the concentration of grafted ZnO as compared with nongrafted, whereby the potential was the highest at day seven. There was a significant decrease in compressive strength and Vickers hardness of commercial composites on addition of grafted ZnO while there was no significant difference in the strength of experimental novel composite. The abrasive wear of commercial and experimental composites was within clinical limits. Low-temperature flow-synthesis method was successfully employed to synthesize grafted and nongrafted ZnO. The UDMA-grafted ZnO can be incorporated into dental composites without decreasing their strength and these composites can be used to combat secondary caries.

Fluorescence quenching mediated detection of hydrogen peroxide using tungsten incorporated graphitic carbon nitride nanoflakes

A reliable, non-enzymatic detection for H₂O₂ with high sensitivity and accuracy is of profound importance and getting considerable interest due to its usefulness in biological systems. Therefore, this work was aimed to develop a sensitive method for the detection of H₂O₂ using rhodamine B as a fluorescence system and tungsten doped graphitic carbon nitride (W/GCN) as catalysts. Fluorescence quenching and colorimetric properties of the chromogenic-dye probe were used as a detection strategy of H₂O₂. The enhanced catalytic property of nanoflakes of W/GCN was attributed to the unique structural characteristics, influenced by the dopant, that not only tuned its bandgap but also enhanced separation of electron-hole pairs as compared to planar and larger sized nanosheets of pristine GCN. This low-cost and rapid assay offered a very low limit of detection of 8 nM for the fluorescence quenching method and 20 nM for the colorimetric method. The linear range for fluorescence quenching and colorimetric H₂O₂ assays were from 10-500 nM and 35-400 nM, respectively. Therefore, this novel method of using W/GCN nanoflakes in fluorescence quenching and colorimetric based detections of H₂O₂ is expected to catch more interest on the topic of using non-enzymatic platforms for sensitive and selective detection of different analysts.

Surface-modified polymeric nanoparticles for drug delivery to cancer cells

INTRODUCTION

The utilization of polymeric nanoparticles, as drug payloads, has been extensively prevailed in cancer therapy. However, the precise distribution of these nanocarriers is restrained by various physiological and cellular obstacles. Nanoparticles must avoid nonspecific interactions with healthy cells and in vivo compartments to circumvent these barriers. Since in vivo interactions of nanoparticles are mainly dependent on surface properties of nanoparticles, efficient control on surface constituents is necessary for the determination of nanoparticles' fate in the body.

AREAS COVERED

In this review, the surface-modified polymeric nanoparticles and their utilization in cancer treatment were elaborated. First, the interaction of nanoparticles with numerous in vivo barriers was highlighted. Second, different strategies to overcome these obstacles were described. Third, some inspiring examples of surface-modified nanoparticles were presented. Later, fabrication and characterization methods of surface-modified nanoparticles were discussed. Finally, the applications of these nanoparticles in different routes of treatments were explored.

EXPERT OPINION

Surface modification of anticancer drug-loaded polymeric nanoparticles can enhance the efficacy, selective targeting, and biodistribution of the anticancer drug at the tumor site.

Developing affordable and accessible pro-angiogenic wound dressings; incorporation of 2 deoxy D-ribose (2dDR) into cotton fibres and wax-coated cotton fibres

The absorption capacity of cotton dressings is a critical factor in their widespread use where they help absorb wound exudate. Cotton wax dressings, in contrast, are used for wounds where care is taken to avoid adhesion of dressings to sensitive wounds such as burn injuries. Accordingly, we explored the loading of 2-deoxy-D-ribose (2dDR), a small sugar, which stimulates angiogenesis and wound healing in normal and diabetic rats, into both types of dressings and measured the release of it over several days. The results showed that approximately 90% of 2dDR was released between 3 and 5 days when loaded into cotton dressings. For wax-coated cotton dressings, several methods of loading of 2dDR were explored. A strategy similar to the commercial wax coating methodology was found the best protocol which provided a sustained release over 5 days. Cytotoxicity analysis of 2dDR loaded cotton dressing showed that the dressing stimulated metabolic activity of fibroblasts over 7 days confirming the non-toxic nature of this sugar-loaded dressings. The results of the chick chorioallantoic membrane (CAM) assay demonstrated a strong angiogenic response to both 2dDR loaded cotton dressing and to 2dDR loaded cotton wax dressings. Both dressings were found to increase the number of newly formed blood vessels significantly when observed macroscopically and histologically. We conclude this study offers a simple approach to developing affordable wound dressings as both have the potential to be evaluated as pro-active dressings to stimulate wound healing in wounds where management of exudate or prevention of adherence to the wounds are clinical requirements.

Oxygen Generating Polymeric Nano Fibers That Stimulate Angiogenesis and Show Efficient Wound Healing in a Diabetic Wound Model

Introduction

Diabetic wounds are challenging to treat due to a wide range of pathophysiological changes. Hypoxia is one of the predominant contributing factors of poor vascularization and chronicity in diabetic wounds. This study was designed to develop polycaprolactone (PCL)-based oxygen-releasing electrospun wound dressings and evaluate their efficacy for improved full thickness wound healing in diabetic rats.

Methods

PCL-based oxygen releasing wound dressings were made using electrospinning technology. The developed dressings were characterized in terms of physical as well as biological properties both in vitro and in vivo. E-spun nanofibrous dressings were physically characterized with scanning electron microscopy, Fourier-transform infrared spectroscopy, and Energy-dispersive X-ray spectroscopy. To study the likely impact of the fabricated wound dressings in hypoxic conditions, HIF-1α expression analysis was carried out both at gene and protein levels. Wound dressings were further evaluated for their healing potential for extensive wounds in diabetic rat models.

Results

The experimental results showed that the developed dressings were capable of continuously generating oxygen for up to 10 days. Cell studies further confirmed pronounced expression of HIF-1α at gene and protein levels in cells seeded on PCL-sodium percarbonate (SPC) and PCL scaffolds compared with the cells cultured on a tissue culture plate. Chorioallantoic membrane assay revealed the supportive role of oxygen releasing dressings on angiogenesis compared to the control group. Histological assessment of the regenerated skin tissues proved that full thickness wounds covered with SPC loaded PCL dressings had a comparatively better vascularized and compact extracellular matrix with completely covered thick epithelium.

Discussion

The developed oxygen generating polymeric nanofibrous wound dressings could potentially be used as an envisioned approach for the efficient recovery of chronic diabetic wounds.

Effectiveness of Thymoquinone and Fluoridated Bioactive Glass/Nano-Oxide Contained Dentifrices on Abrasion and Dentine Tubules Occlusion: An Ex Vivo Study

Objectives  Dentin hypersensitivity (DH) is mainly due to the loss and replenishment of minerals from tooth structure, where the lost minerals can be rehabilitated with a biomimetic approach. The objectives were to determine the relative dentin abrasivity (RDA) of experimental (EXT) dentifrices and to determine the efficacy to occlude dentinal tubules.

Materials and Methods  Experimental dentifrices contained nano-fluoridated bioactive glass (n-FBG: 1.5 wt.% [EXT-A], 2.5 wt.% [EXT-B], and 3.5 wt.% [EXT-C]), nano-zinc oxide (n-ZnO), and thymoquinone as active agents. Bovine dentin blocks were subjected to brushing treatments as per groups, that is, distilled water; commercial dentifrice (control, CT); EXT toothpastes; and EXT-D without active agents. Samples were tested for three-dimensional (3D) abrasion analysis according to ISO-11609:2010 (International Organization for Standardization [ISO]). The roughness average (Ra), RDA, surface topography, and elemental compositions were investigated.

Statistical Analysis  One-way analysis of variance (ANOVA) with post-hoc Tukey’s and Tamhane’s test was performed for characterizations using Statistical Package for the Social Sciences (SPSS) version 21. The result was considered significant with p -value ≤ 0.05.

Results  Comparisons of Ra differed significantly between all groups with p < 0.05 except CT and EXT-A. The RDA values of EXT-A, EXT-B, and EXT-C were calculated as 74.04, 84.26, and 116.24, respectively, which were well within the acceptable limit set by international standards. All n-FBG containing dentifrices demonstrated uniform occlusion of dentinal tubules; however, highly concentrated EXT dentifrices showed more occlusion.

Conclusions  Acceptable range of RDA and superior occlusion of tubules by novel dentifrices suggest that it may be recommended for treating DH.

Comparative Fluoride Release and Antimicrobial Analysis of Commercial and Experimental Bioactive Glass/Nano-Oxide-Based Dentifrices

OBJECTIVES

 The objectives were to measure fluoride release and assess the antimicrobial behavior of fluoride-doped nano bioactive glass (F-nBG) and nano zinc oxide (ZnO)-enriched novel dentifrices.

MATERIALS AND METHODS

 Experimental dentifrices were synthesized by incorporating ZnO nanoparticles and F-nBG (1.5 wt% and 4 wt%) as active ingredients. The fluoride release behavior of suspensions and elutes of samples were analyzed by ion selective electrode. Antimicrobial activity and minimum bactericidal concentration against Streptococcus mutans and Lactobacillus casei were evaluated. Microbial stability against contamination was also assessed by a challenge test.

RESULTS

 The fluoride release behavior of experimental dentifrices was higher than that of commercial dentifrices and was dependent on filler loading. The fluoride release was more from suspensions than elutes. Zones of inhibition (ZOIs) and minimum bactericidal concentration values for novel dentifrices showed direct proportionality with filler loading, and effectiveness was exhibited against both strains. Experimental dentifrices exhibited effective antibacterial potential, which could possibly be due to release of sufficient fluoride and zinc ions in aqueous media from F-nBG and ZnO present in their formulations.

CONCLUSION

 Combination of F-nBG and ZnO may provide a multi-benefit approach for simultaneously treating early white spot lesions, reducing bacterial growth, and providing core plaque control.

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.

Fabrication, in vitro and in vivo studies of bilayer composite membrane for periodontal guided tissue regeneration

Development of a guided occlusive biodegradable membrane with controlled morphology in order to restrict the ingrowth of epithelial cells is still a challenge in dental tissue engineering. A bilayer membrane with a non-porous upper layer (polyurethane) and porous lower layer (polycaprolactone and bioactive glass composite) with thermoelastic properties to sustain surgery treatment was developed by lyophilization. Morphology, porosity, and layers attachment were controlled by using the multi-solvent system. In vitro and in vivo biocompatibility, cell attachment, and cell proliferation were analyzed by immunohistochemistry and histology. The cell proliferation rate and cell attachment results showed good biocompatibility of both surfaces, though cell metabolic activity was better on the polycaprolactone-bioactive glass surface. Furthermore, the cells were viable, adhered, and proliferated well on the lower porous bioactive surface, while non-porous polyurethane surface demonstrated low cell attachment, which was deliberately designed and a pre-requisite for guided tissue regeneration/guided bone regeneration membranes. In addition, in vivo studies performed in a rat model for six weeks revealed good compatibility of membranes. Histological analysis (staining with hematoxylin and eosin) indicated no signs of inflammation or accumulation of host immune cells. These results suggested that the fabricated biocompatible bilayer membrane has the potential for use in periodontal tissue regeneration.

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.

Heparin binding chitosan derivatives for production of pro-angiogenic hydrogels for promoting tissue healing

Our aim was to develop a biocompatible hydrogel that could be soaked in heparin and placed on wound beds to improve the vasculature of poorly vascularized wound beds. In the current study, a methodology was developed for the synthesis of a new chitosan derivative (CSD-1). Hydrogels were synthesized by blending CSD-1 for either 4 or 24h with polyvinyl alcohol (PVA). The physical/chemical interactions and the presence of specific functional groups were confirmed by Fourier transform infrared (FT-IR) spectroscopy and proton nuclear magnetic resonance (¹H NMR). The porous nature of the hydrogels was confirmed by scanning electron microscopy (SEM). Thermal gravimetric analysis (TGA) showed that these hydrogels have good thermal stability which was slightly increased as the blending time was increased. Hydrogels produced with 24h of blending supported cell attachment more and could be loaded with heparin to induce new blood vessel formation in a chick chorionic allantoic membrane assay.

Triethyl orthoformate covalently cross-linked chitosan-(poly vinyl) alcohol based biodegradable scaffolds with heparin-binding ability for promoting neovascularisation

There is a need to develop pro-angiogenic biomaterials to promote wound healing and to assist in regenerative medicine. To this end, various growth factors have been exploited which have the potential to promote angiogenesis. However, these are generally expensive and labile which limits their effectiveness. An alternative approach is to immobilize heparin onto biocompatible degradable hydrogels. The heparin in turn will then bind endogenous proangiogenic growth factors to induce formation of new blood vessels.

In this study, we continue our development of hydrogels for wound healing purposes by exploring covalently cross-linking chitosan and polyvinyl alcohol hydrogels using triethyl orthoformate. Two concentrations of triethyl orthoformate (4 and 16%) were compared for their effects on the structure of hydrogels – their swelling, pore size, and rate of degradation and for their ability to support the growth of cells and for their heparin-binding capacity and their effects on angiogenesis in a chick chorioallantoic membrane assay.

Hydrogels formed with 4 or 16% both triethyl orthoformate cross-linker were equally cyto-compatible. Hydrogels formed with 4% triethyl orthoformate absorbed slightly more water than those made with 16% triethyl orthoformate and broke down slightly faster than non-cross-linked hydrogels. When soaked in heparin the hydrogel formed with 16% triethyl orthoformate showed more blood vessel formation in the CAM assay than that formed with 4% triethyl orthoformate.

Efficient drug delivery system for bone repair by tuning the surface of hydroxyapatite particles

Efficient drug delivery vehicles, hydroxyapatite modified by carboxylic acids, were prepared by an in situ co-precipitation method. The presence of functional groups and subsequent surface properties of modified HA improved ibuprofen loading and release efficiency.

Biological behavior of bioactive glasses and their composites

This review summarizes current developments in improving the biological behavior of bioactive glasse and their composites.

Triethyl orthoformate mediated a novel crosslinking method for the preparation of hydrogels for tissue engineering applications: characterization and in vitro cytocompatibility analysis

This paper describes the development of a new crosslinking method for the synthesis of novel hydrogel films from chitosan and PVA for potential use in various biomedical applications. These hydrogel membranes were synthesized by blending different ratios of chitosan (CS) and poly(vinyl alcohol) (PVA) solutions and were crosslinked with 2.5% (w/v) triethyl orthoformate (TEOF) in the presence of 17% (w/v) sulfuric acid. The physical/chemical interactions and the presence of specific functional groups in the synthesized materials were evaluated by Fourier transform infrared (FT-IR) spectroscopy. The morphology, structure and pore size of the materials were investigated by scanning electron microscopy (SEM). Thermal gravimetric analysis (TGA) proved that these crosslinked hydrogel films have good thermal stability which was decreased as the CS ratio was increased. Differential scanning calorimetry (DSC) exhibited that CS and PVA were present in the amorphous form. The solution absorption properties were performed in phosphate buffer saline (PBS) solution of pH7.4. The 20% PVA-80% CS crosslinked hydrogel films showed a greater degree of solution absorption (183%) as compared to other compositions. The hydrogels with greater CS concentration (60% and 80%) demonstrated relatively more porous structure, better cell viability and proliferation and also revealed good blood clotting ability even after crosslinking. Based on the observed facts these hydrogels can be tailored for their potential utilization in wound healing and skin tissue engineering applications.

Synthesis of piroxicam loaded novel electrospun biodegradable nanocomposite scaffolds for periodontal regeneration

Development of biodegradable composites having the ability to suppress or eliminate the pathogenic micro-biota or modulate the inflammatory response has attracted great interest in order to limit/repair periodontal tissue destruction. The present report includes the development of non-steroidal anti-inflammatory drug encapsulated novel biodegradable chitosan (CS)/poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) electro-spun (e-spun) composite nanofibrous mats and films and study of the effect of heat treatment on fibers and films morphology. It also describes comparative in-vitro drug release profiles from heat treated and control (non-heat treated) nanofibrous mats and films containing varying concentrations of piroxicam (PX). Electrospinning was used to obtain drug loaded ultrafine fibrous mats. The physical/chemical interactions were evaluated by Fourier Transform Infrared (FT-IR) spectroscopy. The morphology, structure and pore size of the materials were investigated by scanning electron microscopy (SEM). The thermal behavior of the materials was investigated by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Control (not heat treated) and heat treated e-spun fibers mats and films were tested for in vitro drug release studies at physiological pH7.4 and initially, as per requirement burst release patterns were observed from both fibers and films and later sustained release profiles were noted. In vitro cytocompatibility was performed using VERO cell line of epithelial cells and all the synthesized materials were found to be non-cytotoxic. The current observations suggested that these materials are potential candidates for periodontal regeneration.

Gold nanoparticle decorated single walled carbon nanotube nanocomposite with synergistic peroxidase like activity for d-alanine detection

In this report, a gold nanoparticle decorated single walled carbon nanotube (SWCNTs) nanocomposite was shown to possess synergistic intrinsic peroxidase like activity and enhanced affinity towards H₂O₂ oxidation.

Hazardous drinking is associated with an elevated aspartate aminotransferase to platelet ratio index in an urban HIV-infected clinical cohort

OBJECTIVES

The aim of the study was to determine the relationship between alcohol consumption and liver fibrosis as assessed by aspartate aminotransferase to platelet ratio index (APRI) in HIV-infected adults and to explore the relative contributions of alcohol and hepatitis C virus (HCV) to APRI among HIV/HCV-coinfected adults.

METHODS

We performed a cross-sectional analysis of data from an observational clinical cohort. Alcohol consumption was categorized according to National Institute on Alcohol Abuse and Alcoholism guidelines. We defined significant liver disease as APRI>1.5, and used multinomial logistic regression to identify correlates of increased APRI.

RESULTS

Among 1358 participants, 10.4% reported hazardous drinking. It was found that 11.6% had APRI>1.5, indicating liver fibrosis. Hazardous drinking was associated with increased APRI [adjusted relative risk ratio (RRR) 2.30; 95% confidence interval (CI) 1.26-4.17]. Other factors associated with increased APRI were male gender, viral hepatitis, and HIV transmission category of injecting drug use. Among coinfected individuals, 18.3% had APRI>1.5, and hazardous drinking was not associated with APRI. Among non-HCV-infected individuals, 5.3% had APRI>1.5 and hazardous drinking was associated with increased APRI (adjusted RRR 3.72; 95% CI 1.40-9.87).

CONCLUSIONS

Hazardous drinking is an important modifiable risk factor for liver fibrosis, particularly among non-HCV-infected patients. Clinicians and researchers must address alcohol use as the burden of liver disease increases among HIV-positive individuals.

Pulmonary haemosiderosis associated with left atrial myxoma

A patient with features suggesting pulmonary haemosiderosis was found to have a myxoma. The pulmonary lesion cleared after excision of the tumour.

Impaired marrow granulocyte reserve and leukocyte mobilization in leukemic reticuloendotheliosis

Cytotoxic chemotherapy often induces sustained, severe granulocytopenia in patients with leukemic reticuloendotheliosis. Many of the patients so treated subsequently develop serious infections. Poor marrow reserve has been implicated but lacks supporting evidence as the cause of the granulocytopenia. In six patients we studied with leukemic reticuloendotheliosis, bone marrow showed severe granulocytopenia, blood neutrophil response after intravenous hydrocortisone injection was poor, and leukocyte migration to the site of inflammation showed suboptimal neutrophilia and poor or no mononuclear response. Splenic hypersequestration and pooling were probably not important factors in causing neutropenia, since similar results were seen in patients without spleens. These findings suggest that in this disease the marrow granulocyte reserve and leukocyte mobilization are impaired and the neutropenia is due to poor granulocyte production and not to increased migration of leukocytes to tissues. Cytotoxic chemotherapy should be used with caution in patients with this disease.