Printing tissue-engineered scaffolds made of polycaprolactone and nano-hydroxyapatite with mechanical properties appropriate for trabecular bone substitutes.

BACKGROUND: Bone tissue engineering, based on three-dimensional (3D) printing technology, has emerged as a promising approach to treat bone defects using scaffolds. The objective of this study was to investigate the influence of porosity and internal structure on the mechanical properties of scaffolds. METHODS: We fabricated composite scaffolds (which aimed to replicate trabecular bone) from polycaprolactone (PCL) reinforced with 30% (wt.) nano-hydroxyapatite (nHAp) by extrusion printing. Scaffolds with various porosities were designed and fabricated with and without an interlayer offset, termed as staggered and lattice structure, respectively. Mechanical compressive testing was performed to determine scaffold elastic modulus and yield strength. Linear regression was used to evaluate mechanical properties as a function of scaffold porosity. RESULTS: Different relationships between mechanical properties and porosities were noted for the staggered and lattice structures. For elastic moduli, the two relationships intersected (porosity = 55%) such that the lattice structure exhibited higher moduli with porosity values greater than the intersection point; vice versa for the staggered structure. The lattice structure exhibited higher yield strength at all porosities. Mechanical testing results also indicated elastic moduli and yield strength properties comparable to trabecular bone (elastic moduli: 14-165 MPa; yield strength: 0.9-10 MPa). CONCLUSIONS: Taken together, this study demonstrates that scaffolds printed from PCL/30% (wt.) nHAp with lattice and staggered structure offer promise for treating trabecular bone defects. This study identified the effect of porosity and internal structure on scaffold mechanical properties and provided suggestions for developing scaffolds with mechanical properties for substituting trabecular bone.

Green Route Synthesis and Characterization Techniques of Silver Nanoparticles and Their Biological Adeptness.

The development of the most reliable and green techniques for nanoparticle synthesis is an emerging step in the area of green nanotechnology. Many conventional approaches used for nanoparticle (NP) synthesis are expensive, deadly, and nonenvironmental. In this new era of nanotechnology, to overcome such concerns, natural sources which work as capping and reducing agents, including bacteria, fungi, biopolymers, and plants, are suitable candidates for synthesizing AgNPs. The surface morphology and applications of AgNPs are significantly pretentious to the experimental conditions by which they are synthesized. Available scattered information on the synthesis of AgNPs comprises the influence of altered constraints and characterization methods such as FTIR, UV-vis, DLS, SEM, TEM, XRD, EDX, etc. and their properties and applications. This review focuses on all the above-mentioned natural sources that have been used for AgNP synthesis recently. The green routes to synthesize AgNPs have established effective applications in various areas, including biosensors, magnetic resonance imaging (MRI), cancer treatment, surface-enhanced Raman spectroscopy (SERS), antimicrobial agents, drug delivery, gene therapy, DNA analysis, etc. The existing boundaries and prospects for metal nanoparticle synthesis by the green route are also discussed herein.

Deconvoluting error in measurement of low angle misorientation distribution.

Misorientation angle distribution gives information about the type and fraction of grain boundaries present in a material. Since grain boundaries affect various mechanical and functional properties of the material, the distribution of grain boundary misorientation is important in order to evaluate these properties. This becomes particularly important when we want to study the microstructure in finer detail, such as understanding the average misorientation within a grain. One of the techniques increasingly used in past two decades for characterization of grain boundary misorientation is electron back scatter diffraction (EBSD). Reliable detection of very small misorientation angles using conventional EBSD system is quite challenging due to the presence of measurement error. This makes the comprehensive characterization of microstructures difficult and prone to error. In order to prevent such problems, it is important to understand the nature of measurement error and find ways to minimize it. The present work aims to elucidate the effect of measurement error on the observed misorientation angle and its statistical distribution in low misorientation angle regime. A true strain of 0.3 was imposed during cold-rolling of Cu-5%Zn alloy sample. The rolled sample was then subjected to in-situ heating from room temperature to 500 °C (∼0.58 Tm). It was found that the overall measurement error in misorientation distribution consists of random error caused by limited angular precision and systematic error which manifests primarily in the statistical distribution of low angle misorientation. In this work, we show a way to deconvolute this overall error based on the measurement technique. We further show that this systematic error is not limited to any particular measurement technique, rather related to the presence of a lower bound in the measurement.

From Synthesis to Biological Impact of Pd (II) Complexes: Synthesis, Characterization, and Antimicrobial and Scavenging Activity.

The Pd (II) complexes with a series of halosubstituted benzylamine ligands (BLs) have been synthesized and characterized with different spectroscopic technique such as FTIR, UV/Vis, LCMS, (1)H, and (13)C NMR. Their molecular sustainability in different solvents such as DMSO, DMSO : H2O, and DMSO : PBS at physiological condition (pH 7.2) was determined by UV/Vis spectrophotometer. The in vitro antibacterial and antifungal activities of the complexes were investigated against Gram-positive and Gram-negative microbes and two different fungi indicated their significant biological potential. Additionally, their antioxidant activity has been analyzed with DPPH(•) free radical through spectrophotometric method and the result inferred them as an antioxidant. The stronger antibacterial and antioxidant activities of the synthesized complexes suggested them as a stronger antimicrobial agent. Our study advances the biological importance of palladium (II) amine complexes in the field of antimicrobial and antioxidant activities.

Biological Impact of Pd (II) Complexes: Synthesis, Spectral Characterization, In Vitro Anticancer, CT-DNA Binding, and Antioxidant Activities.

A new series of Pd (II) complexes of methyl substituted benzylamine ligands (BLs) has been synthesized and characterized via spectroscopic techniques such as UV/Vis. FTIR, LCMS, (1)H, and (13)C NMR. The UV/Vis study in DMSO, DMSO + water, and DMSO + PBS buffer (pH = 7.2) confirmed their molecular sustainability in liquids. Their in vitro anticancer activity against breast cancer cell lines such as MCF-7 and MDA-MB-231 makes them interesting for in vivo analysis. Their stronger DNA binding activity (DBA) compared with free ligand suggested them as a good DNA binder. DBA was further confirmed by physicochemical studies such as surface tension and viscosity of complex + DNA which inferred the disruption of DNA and intercalation of complexes, respectively. Their % binding activity, % disruption of DNA base pairs (DNABP), and % intercalating strength are reported in this paper for the first time for better understanding of DNA binding mechanism. Along with this, their scavenging activity (SA) determined through DPPH free radical and the results indicate good antioxidant behaviour of complexes.

Ectomychorrizal DB: a symbiotic association database.

UNLABELLED: Ectomycorrhizal (ECM) fungal species, a "Symbiotic" relationship between tress and fungi in forest has a great ecological and economic importance. Here is an attempt to describe database named "EctomycorrhizalDB", addressing ECM diversity of Central Himalaya (Kumaun region), with special emphasis on their characterization, physical properties and morphological features along with specifications. This database would help the scientific community to draw a better understanding of the environmental factors that affects species diversity. AVAILABILITY: The database is available for free at http://www.kubic.nic.in/ectomychorhiza.