Self-Cross-Linked Tannin-Aminated Tannin Surface Coatings for Particleboard

Aminated tannins were prepared by reacting mimosa condensed tannin extract with ammonia yielding the substitution of many,if not all of the tannin hydroxyl groups with–NH_(2)groups.A tannin-aminated tannin(ATT)particleboard coating was then prepared by reacting raw tannin extract with aminated tannin extract and thus cross-linking the two by substituting tannin’s hydroxyl groups with the–NH_(2)groups on the aminated tannin to form–NH-bridges between the two.The resulting particleboard coating gave encouraging results when pressed at 180℃for 3 min.Conversely,the system in which tannin was reacted/cross-liked with urea(ATU)by a similar amination reaction did not perform as well as the ATT system,and this even when a higher curing temperature and longer hot press time were used.In particular its water repellence was worse probably due to the presence of urea and such a system with lower reactivity.Nonetheless,substituting the tannin–OHs with the urea–NH_(2)groups appeared to also take place.ATT gave better results than ATU as regards water repellence and mechanical resistance as shown by the cross cut test.The ATT system was shown to be between 95%and 98%biosourced.The difference appeared to be due,by TMA analysis,to the much faster formation of the ATT hardened network leading to a better cross-linked polymer coating.The chemical species formed for both the ATT and ATU system were studied by MALDI ToF and CP MAS^(13)C NMR.

PLASMA SPRAYED Ti AND HA COATINGS: A COMPARATIVE STUDY BETWEEN APS AND VPS

Titanium (Ti) and hydroxyapatite (HA) coatings have been prepared via air (APS) and vacuum plasma spraying (VPS), and then their composition, structure, bonding strength and bioactivity were examined. The results obtained reveal that in APS process many of Ti were oxidized, but in VPS the oxidization was avoided. VPS T i coating possesses better bonding condition than APS Ti coating. As for HA coat ing, higher crystallinity has been obtained while the coating was deposited by V PS as compared with APS. The simulated body fluid (SBF) tests show that both of APS and VPS HA coatings possess good bioactivity. As compared with APS, VPS is r ecommended as a better method to deposit Ti and HA coatings that can be applied as hard tissue replacement implants.

Modification of titanium surface via Ag-,Sr-and Si-containing micro-arc calcium phosphate coating

The current research is devoted to the study of the modification of the titanium implants by the micro-arc oxidation with bioactive calcium phosphate coatings containing Ag or Sr and Si elements.The coatings’microstructure,phase composition,morphology,physicochemical and biological properties were examined by scanning electron microscopy(SEM),transmission electron microscopy(TEM),energy-dispersive X-ray spectroscopy(EDX)and X-ray diffraction(XRD).Ag-containing and Sr-Si-incorporated coatings were formed in alkaline and acid electrolytes,respectively.The formation of the coatings occurred at different ranges of the applied voltages,which led to the significant difference in the coatings properties.The trace elements Ag,Sr and Si participated intensively in the plasma-chemical reactions of the micro-arc coatings formation.Ag-containing coatings demonstrated strong antibacterial effect against Staphylococcus aureus AТСС6538-P.MTT in vitro test with 3T3-L1 fibroblasts showed no cytotoxicity appearance on Sr-Si-incorporated coatings.

Comparative investigations of structure and properties of micro-arc wollastonite-calcium phosphate coatings on titanium and zirconiumniobium alloy

Investigation results of micro-arc wollastoniteecalcium phosphate(W-CaP)biocoatings on the pure titanium(Ti)and Zr-1wt.%Nb(Zr-1Nb)alloy were presented.The voltages of 150-300 V generate the micro-arc oxidation(MAO)process with the initial amplitude current of 150-550 A and 100-350 A for Ti and Zr-1Nb substrates,respectively.The identical dependencies of changes of the coating thickness,surface roughness and adhesion strength on the process voltage were revealed for the both substrates.The W-CaP coatings with the thickness of 10-11μm were formed on Ti and Zr-1Nb under the low process voltage of 130-150 V.Elongated wollastonite particles with the size in the range of 40-100μm were observed in such coatings.The structure of the coatings on Ti was presented by the X-ray amorphous and crystalline phases.The X-ray reflexes relating to the crystalline phases of Ti and wollastonite were observed only in XRD patterns of the coatings deposited under 130-200 V on Ti.While,the crystalline structure with phases of CaZr4(PO4)6,β-ZrP2O7,ZrO2,and Zr was detected in the coatings on Zr-1Nb.FT-IRS,XRD,SEM,and TEM data confirmed that the increase of the process voltage to 300 V leads to the dissociation of the wollastonite.No toxic effect of specimens on a viability,morphology and motility of human adipose-derived multipotent mesenchymal stem cells was revealed in vitro.

A potential flower-like coating consisting of calcium-phosphate nanosheets on titanium surface

Titanium and its alloys have been widely used as implant materials in bio-medicine.Additionally,surface modification has been utilized to improve the chemical and morphological properties of materials.More specifically,biocoating,especially the calcium-phosphate nano-coating,has been widely used in the research field.In this study,a novel calcium-phosphate nanoflower coating was performed on the titanium surface by a simple approach.This study indicated that the novel calcium-phosphate flower-like coating consisting of calcium-phosphate nanosheets had high surface area,low cytotoxicity as well as promising cell affinity.Hence it could be a potential alternative modification method for titanium.

A cell retrievable strategy for harvesting extracellular matrix as active biointerface

Extracellular matrix(ECM) provides a variety of physical and chemical cues for cells. Here, a very simple and smart method is developed to glue living cells away for harvesting their ECMs. The obtained ECM coatings show less cell fragment residues comparing with those obtained by the traditional cell lysis. The glued cell sheets can even be re-cultured and reused after transferring to new environment. This moderate way well maintains the activity of the ECM proteins, which can promote cell adhesion and growth.Strikingly, the ECM coatings acquired from different functional cells can guide stem cell differentiation,which is attributed to the natural physical and biochemical cues on ECM coatings. Consequently, this method provides a substantial progress for preparing natural ECM coatings and shows promising potential in regenerative medicine and other related fields of biomedical engineering.