Removal of alpha case on titanium alloy surfaces using chemical milling

Elevated temperature deformation processing of titanium such as during forging causes the formation of alpha case, a brittle layer on the processed components. Alpha case removal has been attempted by several methods, however, in-depth understanding of chemical milling to this end is not evident from the prevailing literature. This work therefore undertakes experimental analysis of chemical milling to remove alpha case generated on titanium alloys after deformation after forging. Several compositions of chemicals and heat treatment conditions for titanium work-material were evolved. Effectiveness of these methods and their applications in removing alpha case on forged titanium alloy were investigated by performing a series of experiments. After the alpha case removal, the titanium work surfaces were examined using optical and scanning electron microscopy as well as electron back scattered diffraction and X-ray diffraction. The optimum results achieved show that 8% HF and 10% HNO3 solution with 13min and 30-s etching time is more effective in completely removing alpha case layer by chemical etching of Ti-6Al-4V alloy work specimens heated in air at 930 degrees C

Human Fallopian tube as a novel source of multipotent stem cells with potential for islet neogenesis

Presence of stem cells in the female genital tract has been reported; however stem cell status of Fallopian tube remains unexplored. In the present study, we show for the first time an existence of stem cells in a Fallopian tube.? A pure population of mesenchymal like cells was obtained from the Fallopian tube samples from patients undergoing hysterectomy. The immunocytochemistry of these cells revealed the presence of classical mesenchymal stem cell markers like smooth muscle actin, vimetin, nestin, desmin, CD44, CD90 and CD117.? These Fallopian Tube derived Mesenchymal stem cells could be induced to differentiate into adipocytes, chondrocytes, osteocytes, neuronal and pancreatic lineage under the influence of lineage specific differentiation cocktails. Such documentation of multipotent stem cells in a Fallopian tube may be of significance for instant repair of the tract as and when necessary so as to assist uninterrupted transport of eggs for possible fertilization thus facilitating reproduction

Improved functionalization of electrospun PLLA/gelatin scaffold by alternate soaking method for bone tissue engineering

Biomimetic biomaterials are widely being explored as scaffold for bone regeneration. In this study, we prepared poly-l-lactic acid/hydroxyapatite (PLLA/HA) and poly-L-lactic acid/gelatin/hydroxyapatite (PLLA/Gel/HA) scaffold by electrospinning of poly-L-lactic acid (PLLA) and a blend of poly-l-lactic acid/gelatin (PLLA/Gel) followed by hydroxyapatite (HA) mineralization via alternate soaking in calcium and phosphate (Ca-P) solutions. HA growth on scaffold after each soaking cycle was confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The functional groups (COO and -NH2) of gelatin in the PLLA/Gel scaffold facilitated the surface nucleation of HA as compared to the PLLA scaffold. Leaching study showed HA in PLLA/Gel/HA scaffold acts as binder of gelatin and eliminates use of toxic crosslinking agents. In vitro cell attachment on these scaffolds was assessed by using human osteosarcoma cells (MG-63). Cell proliferation on scaffolds was examined by MTT assay. MTT results clearly indicated that mineralized scaffolds did not inhibit the eventual cell proliferation. Alkaline phosphatase (ALP) activity of MG-63 cells was found to be the highest on PLLA/Gel/HA at day 7 compared to all other scaffolds. Complement activation study revealed minimum terminal complement complex (TCC) concentration for PLLA/Gel and PLLA/Gel/HA (617.33 and 654.13 ng/mL respectively). These results demonstrate the proficiency of PLLA/Gel/HA scaffold in better osteostimulation with lesser immune response, which attributed to synergistic role of gelatin and HA. Thus, by mimicking the natural microenvironment PLLA/Gel/HA scaffolds can become the choice of material in bone tissue engineering. (C) 2013 Elsevier B.V. All rights reserved

Hardystonite improves biocompatibility and strength of electrospun polycaprolactone nanofibers over hydroxyapatite: A comparative study

The aim of this study was to compare physico-chemical and biological properties of hydroxyapatite (HA) and hardystonite (HS) based composite scaffolds. Hardystonite (Ca2ZnSi2O7) powders were synthesized by a sol-gel method while polycaprolactone-hardystonite (PCL-HS) and polycaprolactone-hydroxyapatite (PCL-HA) were fabricated in nanofibrous form by electrospinning. The physico-chemical and biological properties such as tensile strength, cell proliferation, cell infiltration and alkaline phosphatase activity were determined on both kinds of scaffolds. We found that PCL-HS scaffolds had better mechanical strength compared to PCL-HA scaffolds. Addition of HA and HS particles to PCL did not show any inhibitory effect on blood biocompatibility of scaffolds when assessed by hemolysis assay. The in vitro cellular behavior was evaluated by growing murine adipose-tissue-derived stem cells (mE-ASCs) over the scaffolds. Enhanced cell proliferation and improved cellular infiltrations on PCL-HS scaffolds were observed when compared to HA containing scaffolds. PCL-HS scaffolds exhibited a significant increase in alkaline phosphatase (ALP) activity and better mineralization of the matrix in comparison to PCL-HA scaffolds. These results clearly demonstrate the stimulatory role of Zn and Si present in HS based composite scaffolds, suggesting their potential application for bone tissue engineering. (C) 2013 Elsevier B.V. All rights reserved

Bioconductive 3D nano-composite constructs with tunable elasticity to initiate stem cell growth and induce bone mineralization

Bioactive 3D composites play an important role in advanced biomaterial design to provide molecular coupling and improve integrity with the cellular environment of the native bone. In the present study, a hybrid lyophilized polymer composite blend of anionic charged sodium salt of carboxymethyl chitin and gelatin (CMCh(Na)-GEL) reinforced with nano-rod agglomerated hydroxyapatite (nHA) has been developed with enhanced biocompatibility and tunable elasticity. The scaffolds have an open, uniform and interconnected porous structure with an average pore diameter of 157 +/- 30 mu M and 89.47 + 0.03% with four dimensional X-ray. The aspect ratio of ellipsoidal pores decrease from 4A to 1.2 with increase in gelatin concentration; and from 2.14 to 1.93 with decrease in gelling temperature. The samples were resilient with elastic stain at 1.2 MPa of stress also decreased from 0.33 to 0.23 with increase in gelatin concentration. The crosslinker HMDI (hexamethylene diisocyanate) yielded more resilient samples at 1.2 MPa in comparison to glutaraldehyde. Increased crosslinking time from 2 to 4 h in continuous compression cycle show no improvement in maximum elastic stain of 1.2 MPa stress. This surface elasticity of the scaffold enables the capacity of these materials for adherent self renewal and cultivation of the NTERA-2 cL.D1 (NT2/D1), pluripotent embryonal carcinoma cell with biomechanical surface, as is shown here. Proliferation with MG-63, ALP activity and Alizarin red mineralization assay on optimized scaffold demonstrated ***p < 0.001 between different time points thus showing its potential for bone healing. In pre-clinical study histological bone response of the scaffold construct displayed improved activity of bone regeneration in comparison to self healing of control groups (sham) up to week 07 after implantation in rabbit tibia critical-size defect. Therefore, this nHA-CMCh(Na)-GEL scaffold composite exhibits inherent and efficient physicochemical, mechanical and biological characteristics based on gel concentrations, gelatin mixing and gelling temperature thus points to creating bioactive 3D scaffolds with tunable elasticity for orthopedic applications. (C) 2016 Elsevier B.V. All rights reserved