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Although several bioinks have been developed for 3D bioprinting applications, the lack of optimal printability, mechanical properties, and adequate cell response has limited their practical applicability. Therefore, this work reports the development of a composite bioink consisting of bovine serum albumin (BSA), alginate, and self-assembled nanofibrous polyelectrolyte complex aggregates of gelatin and chitosan (PEC-GC). The nanofibrous PEC-GC aggregates were prepared and incorporated into the bioink in varying concentrations (0 % to 3 %). The bioink samples were bioprinted and crosslinked post-printing by calcium chloride. The average nanofiber diameter of PEC-GC was 62 ± 15 nm. It was demonstrated that PEC-GC improves the printability and cellular adhesion of the developed bioink and modulates the swelling ratio, degradation rate, and mechanical properties of the fabricated scaffold. The in vitro results revealed that the bioink with 2 % PEC-GC had the best post-printing cell viability of the encapsulated MG63 osteosarcoma cells and well oragnized stress fibers, indicating enhanced cell adhesion. The cell viability was >90 %, as observed from the MTT assay. The composite bioink also showed osteogenic potential, as confirmed by the estimation of alkaline phosphatase activity and collagen synthesis assay. This study successfully fabricated a high-shape fidelity bioink with potential in bone tissue engineering. [Display omitted] • Preparation of nanofibrous polyelectrolyte complex of gelatin and chitosan via self-assembly. • Nanofibers in bioink enhances printability, mechanical properties, cell adhesion and proliferation. • High shape-fidelity bioprinted scaffolds have a potential in bone tissue engineering. [ABSTRACT FROM AUTHOR]

Acute hypocalcaemia is a medical emergency that can have catastrophic implications like tetany, seizures, cardiac arrythmias or laryngospasm if left untreated. We are presenting a case of a 30-year-old female patient undergoing total abdominal hysterectomy with bilateral salpingoopherectomy under spinal anaesthesia. She developed unexpected bilateral carpal spasm intraoperatively which was promptly diagnosed and successfully managed with intravenous calcium administration. We conclude that the anaesthetist should be aware of the clinical presentation of acute hypocalcaemia, its causes and emergency management in the perioperative period to prevent any adverse outcomes. [ABSTRACT FROM AUTHOR]

Chitosan-based thermosensitive bioink can be a potential option as bioinks for bone tissue engineering because of their excellent biocompatibility and crosslinker-free gelation at physiological temperature. However, their low mechanical strength, poor printability, and low post-printing cell viability are some of their limitations. In this work, self-assembled nanofibrous aggregates of chitosan and gelatin were prepared and incorporated in chitosan-based bioinks to enhance printability, mechanical properties, post-printing cell viability, and proliferation. Subsequently, the optimal concentration of nanohydroxyapatite was determined, and the potential of the nanocomposite bioink was evaluated. Physiochemical, mechanical, and in vitro characterizations were carried out for the developed nanocomposite bioink. The bioink had optimum printability at 10 % nanohydroxyapatite and cell viability >88 %. The composite bioink had a low water uptake capacity (2.5 %) and degraded within 3 weeks in the presence of lysozyme. Mechanical characterization revealed an elastic modulus of about 15.5 kPa. Rheological analysis indicated a higher storage modulus of the bioink samples at 37 °C. ALP activity of 36.8 units/ml after 14 days of scaffold culture in osteogenic media indicated high cellular activity. These results suggested that the incorporation of osteogenic nanohydroxyapatite and nanofibrous aggregates improved the overall osteogenic and physiochemical potential of the thermosensitive bioink. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Chitosan and guargum based film were prepared by solvent casting method. • Film containing Ag-ZnONP and Tranexamic acid possessed high tensile strength. • Ag-ZnONP content of the film enhanced its therapeutic potential. • The nanocomposite film exhibited excellent antibacterial and antibiofilm properties. • The film promotes rapid hemostasis and facilitates cell proliferation and migration. Modern wound care requires multifunctional dressings that can efficiently control bleeding and subsequent infection, facilitating faster healing which reduces the healthcare costs. Our study aimed to develop a nanocomposite biopolymeric film composed of Ag doped ZnO nanoparticle and drug tranexamic acid (TRA) loaded into chitosan guargum matrix (CGT/AgZnO) for obtaining improved antibacterial, antibiofilm and haemostatic properties, along with potential wound healing effects. The films were developed via solution casting method and characterized by various standard biophysical techniques such as X-ray diffraction, infrared spectroscopy, electron microscopy imaging etc. The polymeric nanocomposite films exhibited strong antibacterial efficacy against bacteria such as E. coli , P. aeruginosa , S. aureus and B. subtilis. The films loaded with 3 wt% of nanoparticles (CGT/AgZnO3) exhibited remarkable growth inhibition i.e. 90% and 94% against gram-negative and gram-positive bacteria, respectively. These films also demonstrated excellent antibiofilm activity, with CGT/AgZnO3 inhibiting over 80% of bacterial biofilm formation after 72 h. The nanocomposite films exhibited a strong hemostatic effect as indicated by their blood clotting index (BCI) value. The in vitro hemocompatibility and cytocompatibility study (against the mouse fibroblast cells- L929 cell line) showed the films were highly biocompatible. The wound closure potential of the films was evaluated using in vitro scratch assays, exhibiting enhanced cell migration (100%) after 24 h, as compared to the control groups (66%). These findings confirmed that the developed CGT/AgZnO films have the potential as an excellent wound dressing material with high antibacterial, hemostatic, and wound healing properties. [ABSTRACT FROM AUTHOR]

Background and Aims: Awake fibreoptic intubation is considered a safe approach in airway management of a patient with difficult airway. Awake fibreoptic endoscopy needs appropriate anaesthesia of airway to suppress airway reflexes and prevent discomfort. We planned this study to evaluate effect of adding dexmedetomidine to lignocaine nebulization on conditions for awake videoendoscopic intubation. Material and Methods: In this prospective randomized double blind controlled study, ninety six ASA grade I, II patients of either gender, aged 18-65 years, scheduled for elective surgeries under general anaesthesia, were randomly allocated into two groups, Group D and L to receive nebulization with 4% Lignocaine 5 ml + Dexmedetomidine 2 mcg/kg and 4% Lignocaine alone respectively, 20 min before procedure. Time taken to intubate the patient, ease of intubation assessed by cough severity score, patient comfort score, post-intubation patient satisfaction and hemodynamic changes were recorded and compared. Results: Group D and L had comparable intubation time (196.8 ± 61.2 s) and (205.8 ± 52.2 s) (p = 0.437). Cough severity, patient comfort and quality of procedure with post intubation patient satisfaction score were significantly better in Group D. Haemodynamics parameters were better post nebulization in group D as compared to group L. Conclusion: Addition of Dexmedetomidine 2 mcg/kg with 4% Lignocaine during nebulization improves intubating conditions during awake flexible videoendoscopy in terms of ease of intubation, cough severity, patients comfort and satisfaction along with providing stable Haemodynamics profile. [ABSTRACT FROM AUTHOR]

Phenol is one of the most common hazardous organic compound presents in several industrial effluents which directly affects the aquatic environment. The present study envisaged the phenol biodegradation and simultaneous lipid production along with its underlying mechanism by oleaginous yeast Rhodosporidium toruloides 9564T. Experiments were designed using simulated wastewater by varying phenol concentration in the range of 0.25–1.5 g/L and inoculum size of 1, 5, and 10% with and without glucose. The oleaginous yeast was found to completely degrade up to 0.75 g/L phenol with lipid accumulation of 26.3%. Phenol at > 0.5 g/L severely inhibited the growth of R. toruloides 9564T at 1% and 5% inoculum size. Phenol toxicity up to 0.75 g/L can be overcome by increasing inoculum size to 10%. The maximum specific growth rate (μ max) and phenol degradation rate (q max) were found to be 0.0717 h−1 and 0.01523 h−1, respectively. The enzymatic pathway study suggested that R. toruloides 9564T follows an ortho cleavage pathway for phenol degradation and lipid accumulation. Phytotoxicty and cytotoxicity tests for treated and untreated samples clearly demonstrated a decline in toxicity of the treated wastewater. R. toruloides brought about an important paradigm shift toward a circular economy in which industrial wastewater is considered a valuable resource for bioenergy production. • R. toruloides 9564T is a potential yeast for phenol degradation upto 0.75 g/L. • R. toruloides 9564T follows an ortho cleavage pathway for phenol degradation. • Haldane's model shows μ max and q max to be 0.0717 h−1 and 0.01523 h−1 respectively. • > 70% cell and seed viability observed for treated samples (0.25–0.50 g/L). [ABSTRACT FROM AUTHOR]

Tensile deformation of a tungsten (W) microstructure is examined at elevated temperatures and at varying levels of irradiation. The computational framework used in this study is based on the finite element (FE) method using the Anand viscoplastic model. In order to account for viscoplasticity at high temperatures, the relevant material parameters of the Anand viscoplastic model have been determined through uniaxial tests upon W samples containing a high level of neutron irradiation. Analyses show that the effect of thermal softening decreases with increase in irradiation dose. In addition, a sigmoidal dependence of irradiation dose on the yield strength of W microstructures is observed. The FE analyses also suggest that the yield strength of W is directly correlated with temperature and irradiation dose. Based on the simulation results, an empirical relation for predicting the yield strength of W is proposed based upon the temperature and irradiation dose. The developed relation is found to predict the yield strength of W well over a wide range of temperatures and irradiation doses. [ABSTRACT FROM AUTHOR]

In present investigation, an attempt has been made for the synthesis of cupric oxide nanoparticles (CuONPs) through a green route by utilizing lemon juice extract as a bioreductant. The synthesized CuONPs were characterized through UV-visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The CuONPs were utilized for Cr(VI) removal from water through adsorption method in batch mode at different initial Cr(VI) concentration, pH, temperature and CuONPs dosage. The maximum uptake capacity of CuONPs was found to be 16.63 mg of Cr(VI)/g at pH 4.0. Implementation of response surface methodology (RSM) followed by artificial neural network hybridized with genetic algorithm (ANN-GA) approach has resulted maximum Cr(VI) adsorption of 98.8% under the optimized conditions of initial metal concentration 22.5 mg/L, pH 3.81, CuONPs dose 1.28 g/L and temperature 37.1 °C. Under optimum conditions, adsorption isotherm study was conducted, which showed that the fitness of experimental data was well achieved with Langmuir isotherm model illustrating monolayer pattern of adsorption. Thermodynamic study revealed that the process was spontaneous and endothermic in nature, while adsorption kinetics was best explained by pseudo-second order kinetic model. [ABSTRACT FROM AUTHOR]

Surgical tourniquets are commonly used in orthopaedic and trauma surgery, but these have their complications. Reperfusion injury following simultaneous release of bilateral tourniquets is the most likely explanation of cardiac arrest in this case. We describe an unusual complication experienced by a 40 year old, 65 kg healthy male who underwent surgery for trauma to the lower extremity (bilateral fracture tibia). Bilateral mid-thigh tourniquets (Esmarch bandage) were applied, which were simultaneously released after 90 min. After 5 min of tourniquet release sudden severe hypotension occurred followed by cardiac arrest. Patient was immediately intubated and cardio pulmonary cerebral resuscitation (CPCR) was started. We conclude that bilateral tourniquet application can be hazardous within the safe limit of tourniquet time (<2 hours) and their simultaneous release should be avoided. Moreover, Esmarch tourniquet may generate very high uncontrolled pressures and should be avoided. [ABSTRACT FROM AUTHOR]

The AgNPs synthesized by green method have shown great potential in several applications such as biosensing, biomedical, catalysis, electronic etc. The present study deals with the selective colorimetric detection of Fe 3 + using photoinduced green synthesized AgNPs. For the synthesis purpose, an aqueous extract of Croton bonplandianum (AEC) was used as a reducing and stabilizing agent. The biosynthesis was confirmed by UV–visible spectroscopy where an SPR band at λ max 436 nm after 40 s and 428 nm after 30 min corresponded to the existence of AgNPs. The optimum conditions for biosynthesis of AgNPs were 30 min sunlight exposure time, 5.0% (v/v) AEC inoculum dose and 4 mM AgNO 3 concentration. The stability of synthesized AgNPs was monitored up to 9 months. The size and shape of AgNPs with average size 19.4 nm were determined by Field Emission Scanning Electron Microscope (FE-SEM) and High-Resolution Transmission Electron Microscope (HR-TEM). The crystallinity was determined by High-Resolution X-ray Diffractometer (HR-XRD) and Selected Area Electron Diffraction (SAED) pattern. The chemical and elemental compositions were determined by Fourier Transformed Infrared Spectroscopy (FTIR) and Energy Dispersive X-ray Spectroscopy (EDX) respectively. The Atomic Force Microscopy (AFM) images represented the lateral and 3D topological characteristics of AgNPs. The XPS analysis confirmed the presence of two individual peaks which attributed to the Ag 3d3/2 and Ag 3d5/2 binding energies corresponding to the presence of metallic silver. The biosynthesized AgNPs showed potent antibacterial activity against both gram-positive and gram-negative bacterial strains as well as antioxidant activity. On the basis of results and facts, a probable mechanism was also proposed to explore the possible route of AgNPs synthesis, colorimetric detection of Fe 3 + , antibacterial and antioxidant activity. [ABSTRACT FROM AUTHOR]

Polylactic acid based spherical particles with three architectural variations (Isotropic (P1), Semi porous (P2), and Janus (P3)) were employed to encapsulate zero valent iron nanoparticles (ZVINPs), and their performance was extensively evaluated in our previous studies. However, little was known about their transportability through saturated porous media of varying grain size kept under varying ionic strength. In this particular study, we aimed to investigate the architectural effect of polymeric particles (P1-P3) on their mobility through the sand column of varying grain size in presence of mono, di, and tri-valent ions of varying concentrations (25-200 mM (millimoles)). As per column breakthrough experiments (BTCs) using various types of sands, amphiphilic Janus type (P3) particles exhibited the maximum transportability among all the tested particles, irrespective of the nature of the sand. Owing to the narrower travel path, sands with lower porosity (31%) delayed the plateau by shifting it to a higher pore volume with a minimum retention of iron (C/C o : 0.94 for P3) in the column. The impact of mono (Na + , K + ), di (Ca 2+ , Mg 2+ ), and trivalent (Al 3+ ) ions on their transportability was progressively increased from P3 to P1, especially at higher ionic concentrations (200 mM), with P3 being the most mobile particles (C/C o :0.54 for Al 3+ ). Among all the ions, Al 3+ exhibited maximum hindrance to their mobility through the sand column. This could be due to their strong charge screening effect coupled with cation bridging complex formation with moving particles. Experimental results obtained from BTCs were found to be well-fitted with a theoretical model based on advection-dispersion equation, showing minimum retention for P3 particles. Overall, it can be inferred that encapsulation of ZVINPs inside Janus particles (P3) with a right balance of amphiphilicity and highly negative surface charge would be required to achieve considerable transportability through sand aquifers to target contaminants in polluted groundwater existing under harsh conditions (high ionic concentrations)., Competing Interests: Declaration of competing interest Authors have nothing to declare., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Tissue adhesives offer a plethora of advantages in achieving efficient wound closure over conventional sutures and staples. Such materials are of great value, especially in cases where suturing could potentially damage tissues or compromise blood flow or in cases of hard-to-reach areas. Besides providing wound closure, the tissue adhesives must also facilitate wound healing. Previously, plasma-based tissue adhesives and similar bioinspired strategies have been utilized to aid in wound healing. Still, their application is constrained by factors such as high cost, diminished biocompatibility, prolonged gelation times, inadequate swelling, quick resorption, as well as short-term and inconsistent efficacy. To address these limitations, we report the development of a highly biocompatible and ultrafast-gelling tissue adhesive hydrogels. Freeze-dried platelet-rich plasma, heat-denatured freeze-dried platelet-poor plasma, and gelatin were utilized as the base matrix. Gelation was initiated by adding tetrakis hydroxymethyl phosphonium chloride. The fabricated gels displayed rapid gelation (3-4 s), low swelling, increased proliferation, and migration against L929 cells and had porcine skin tissue adhesion strength similar to that of plasma-based commercial glue (Tisseel®)., (© 2024 IOP Publishing Ltd.)

Biodegradable drug-eluting stents (DESs) are gaining importance owing to their attractive features, such as complete drug release to the target site. Magnesium (Mg) alloys are promising materials for future biodegradable DESs. However, there are few explorations using biodegradable Mg for cardiovascular stent application. In this present study, sirolimus-loaded poly D, L-lactic-co-glycolic acid (PLGA)-coated/ sirolimus-fixed/AZ91 Mg alloy-based substrate was developed via a layer-by-layer approach for cardiovascular stent application. The AZ91 Mg alloy was prepared through the squeeze casting technique. The casted AZ91 Mg alloy (Mg) was alkali-treated to provide macroporous networks to hold the sirolimus and PLGA layers. The systematic characterization was investigated via electrochemical, optical, physicochemical, and in-vitro biological characteristics. The presence of the Mg 17 Al 12 phase in the Mg sample was found in the x-ray diffraction system (XRD) spectrum which influences the corrosion behavior of the developed substrate. The alkali treatment increases the substrate's hydrophilicity which was confirmed through static contact angle measurement. The anti-corrosion characteristic of casted-AZ91 Mg alloy (Mg) was slightly less than the sirolimus-loaded PLGA-coated alkali-treated AZ91 Mg alloy (Mg/Na/S/P) substrate. However, dissolution rates for both substrates were found to be controlled at cell culture conditions. Radiographic densities of AZ91 Mg alloy substrates (Mg, Mg/Na, and Mg/Na/S/P) were measured to be 0.795 ± 0.015, 0.742 ± 0.01, and 0.712 ± 0.017, respectively. The star-shaped structure of 12% sirolimus/PLGA ensures the bioavailability of the drugs. Sirolimus release kinetic was fitted up to 80% with the "Higuchi model" for Mg samples, whereas Mg/Na/S/P showed 45% fitting with a zero-order mechanism. The Mg/Na/S/P substrate showed a 70% antithrombotic effect compared to control. Further, alkali treatment enhances the antibacterial characteristic of AZ91 Mg alloy. Also, the alkali-treated sirolimus-loaded substrates (Mg/Na/S and Mg/Na/S/P) inhibit the valvular interstitial cell's growth significantly in in-vitro. Hence, the results imply that sirolimus-loaded PLGA-coated AZ91 Mg alloy-based substrate can be a potential candidate for cardiovascular stent application., (© 2023 Wiley Periodicals LLC.)

Non-union of large bone defects has been an existing clinical problem. 3D extrusion-based bioprinting provides an efficient approach to tackle such problems. This approach enables the use of various biomaterials, cell types and growth factors in developing a superior bone graft that is specific to the defect. In this article, we have designed and printed an ECM mimicking, self-assembled polyelectrolyte complex (PEC) based fibrous bioink using natural polymers like chitosan-polygalacturonic acid (PGA) and other biomaterials - gelatin, laponite and nanohydroxyapatite with a modified 3D printer. The developed bioink possesses a thermo-reversible sol-gel transition at physiological pH and temperature. Here, we demonstrated that post-printing, our fiber-reinforced bioink had significant cell proliferation with cell viability of >80% and negligible cell morbidity. The practicability of developing this self-assembled PEC-based bioink was assessed. Bioink with 4% gelatin (PECHLG4) had optimal printability with a minimal swelling ratio of approximately 3%. The printed scaffold had integrity for a period of 8 days under 0.5 mg/mL lysozyme concentration. We also evaluated the mechanical property of the bioink using compression analysis which gave an elastic modulus of 16 KPa. This combination of natural polymers and nanocomposite, along with a fibrous network of PECs, is itself a novel approach for 3D bioprinting and can be a preliminary proposition for the treatment of large bone defects.

Currently, one of the most severe clinical concerns is post-surgical tissue adhesions. Using films or hydrogel to separate the injured tissue from surrounding tissues has proven the most effective method for minimizing adhesions. Therefore, by combining dual crosslinking with calcium ions (Ca 2+ ) and tetrakis(hydroxymethyl) phosphonium chloride, we were able to create a novel, stable, robust, and injectable dual crosslinking hydrogel using albumin (BSA). This dual crosslinking has preserved the microstructure of the hydrogel network during the degradation process, which contributes to the hydrogel's mechanical strength and stability in a physiological situation. At 60% strain, compressive stress was 48.81 kPa obtained. It also demonstrated excellent self-healing characteristics (within 25 min), tissue adhesion, excellent cytocompatibility, and a quick gelling time of 27 ± 6 s. Based on these features, the dual crosslinked injectable hydrogels might find exciting applications in biomedicine, particularly for preventing post-surgical adhesions., (© 2023 IOP Publishing Ltd.)

An extracellular matrix (ECM) mimicking a 3D microenvironment is an essential requirement to achieve desirable repair or regeneration of damaged tissue or organ. In this context, hydrogels may be able to create an appropriate 3D microenvironment. The lack of mechanical stability limits their application. This study prepared and characterized thermosensitive injectable hydrogels based on chitosan and polygalacturonic acid (PgA). A method of producing novel biomimetic polymeric-based injectable hydrogel using hydrothermal assisted hydrolysis is introduced. The synthesized hydrogels showed good compressive stiffness. We have also studied the possible chemistry of the materials in the hydrogel network. The biocompatibility and gelation time of the hydrogel was optimized by adding β-glycerophosphate (βGP) and hydroxyapatite. The synthesized liquid formulation can turn into gel at 37 °C. The biocompatibility for MG63 cells within 3D hydrogels was investigated. Scanning electron microscopy revealed that the PEC fibers are uniformly distributed in the hydrogel matrix. MTT assay and confocal imaging were employed to observe cytotoxicity and proliferation of cells cultured in the hydrogels with and without an osteogenic medium. Alkaline phosphatase activity (ALP) and collagen production in cell-cultured hydrogel were also measured to evaluate osteoblast activity. The cellular responses to various types of hydrogels cultured at a 14-day culture appeared to be superior in the hydrogels with gelatin incorporated and hydrothermally treated PEC fibers. These results indicated that hydrothermal treatment and inclusion of gelatin in the chitosan-βGP hydrogel system enhanced the hydrogel bioactivity and mechanical properties. Overall, improved cellular proliferation, osteogenic differentiation, and stable physical network with uniform distribution of fibrous matrix in-vitro were achieved., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Current study presents an economic, ecofriendly and simple photo-catalytic green route for the swift biosynthesis of silver nanoparticles (AgNPs) within 20s, devoid of any instrumental support or chemical reductant. Aqueous leaf-extract of an aquatic fern, Salvinia molesta (AES), was used as a bioreductant as well as a stabilizing agent. Rapid change in color of reaction mixture from yellowish green to reddish brown within 20s in direct sun light exposure was considered as the primary visual indication of AgNPs biosynthesis. The biosynthesis of AgNPs was confirmed by UV-visible spectroscopy through the presence of a characteristic surface plasmon resonance (SPR) band for AgNPs at λmax of 425 nm. The process parameters were optimized through one factor at a time approach. Optimal values of different process parameters for the current biosynthetic system were found as; 35 min of reaction time under sun light, 8.0mM AgNO3 concentration and 5.0% (v/v) AES inoculum dose. Field emission scanning electron microscopy (FESEM), energy dispersive X-Ray spectroscopy (EDX), high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) analysis showed that most of AgNPs were spherical in shape with average size distribution of 12.46 nm having face centered cubic (fcc) crystal lattice. IR analysis of AES and synthesized AgNPs indicated the involvement of both hydroxyl and amino groups in the biosynthesis and stabilization of AgNPs. The synthesized AgNPs were found to be an effective antibacterial agent against both Gram positive and Gram negative bacteria. On the basis of results and facts, a probable mechanism has also been proposed to explore the possible route of biosynthesis of AgNPs through AES., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The interfaces between organic and inorganic phases in natural materials have a significant effect on their mechanical properties. This work presents a quantification of the interface stress as a function of interface chemical changes (water, organic molecules) in chitin-calcite (CHI-CAL) interfaces using classical non-equilibrium molecular dynamics (NEMD) simulations and steered molecular dynamics (SMD) simulations. NEMD is used to investigate interface stress as a function of applied strain based on the virial stress formulation. SMD is used to understand interface separation mechanism and to calculate interfacial shear stress based on a viscoplastic interfacial sliding model. Analyses indicate that interfacial shear stress combined with shear viscosity can result in variations to the mechanical properties of the examined interfacial material systems. It is further verified with Kelvin-Voigt and Maxwell viscoelastic analytical models representing viscous interfaces and outer matrix. Further analyses show that overall mechanical deformation depends on maximization of interface shear strength in such materials. This work establishes lower and upper bounds of interface strength in the interfaces examined., (Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

In this work, we have investigated osteoblast adhesion, proliferation and differentiation on nanocomposites of chitosan, polygalacturonic acid (PgA) and hydroxyapatite. These studies were done on both two- and three-dimensional (scaffold) samples. Atomic force microscopy experiments showed nanostructuring of film samples. Scaffolds were prepared by freeze-drying methods. The mechanical response and porosity of the scaffolds were also determined. The compressive elastic modulus and compressive strength were determined to be around 0.9 and 0.023 MPa, respectively, and the porosity of these scaffolds was found to be around 97 per cent. Human osteoblast cells were used to study their adhesion, proliferation and differentiation. Optical images were collected after different intervals of time of seeding cells. This study indicated that chitosan/PgA/hydroxyapatite nanocomposite films and scaffolds promote cellular adhesion, proliferation and differentiation. The formation of bone-like nodules was observed after 7 days of seeding cells. The nodule size continues to increase with time, and after 20 days the size of some nodules was around 735 microm. Scanning electron microscope images of nodules showed the presence of extracellular matrix. The alizarin red S staining technique was used to confirm mineralization of these nodules.