A composite (HA/silicone) of hydroxyapatite (HA) microparticles with an average diameter of 2.0 micro m covalently linked to a silicone substrate has been developed, and its physical and biological properties as a percutaneous soft-tissue-compatible material have been evaluated. In tensile property measurement, samples of HA/silicone and the original silicone were similar in tensile strength, ca. 7.8 MPa, and elongation at break, ca. 570%. It was found that chemical surface modification with HA particles presented no mechanical disadvantage. In an adhesive-tape peeling test, scanning electron microscopic (SEM) observation showed that HA particles coupled directly to the substrate were not removed. HA particles may bond strongly with the substrate. In human periodontal ligament fibroblast attachment and proliferation experiments, the number of cells attached to HA/silicone was 14 times greater than that attached to the original silicone after 24 h of incubation. The value on HA/silicone was ca. 80% versus that on a tissue-culture plastic used as a positive control. After 72 h of incubation, the number of cells grown on HA/silicone increased to the level of the positive control. In observation of fluorescence microscopy stained by Hoechst 33342, cells appeared to tightly adhere to HA particles coupled to the silicone sheet due to intact nuclear morphology. Observation of cells by fluorescence dye with rhodamin phalloidin showed an extensive F-actin cytoskeleton on HA/silicone. In a 4-week animal implant test, force required to pull out the HA/silicone sheet was 15 times that of the original silicone. HA-particle coating on silicone with covalent linkage gave the inert surface bioactivity. The HA composite thus effectively prevents germ infection percutaneously.
A novel composite coupling between nano-scaled hydroxyapatite (HAp) particles and poly[4-methacryloyloxyethyl trimellitate anhydride (4-META)]-grafted silk fibroin (SF) through ionic interaction was synthesized. The weight gain of poly(4-META) by graft-polymerization increased with increasing the reaction time, eventually reaching a plateau value of about 20 wt%. The HAp nano-particles were adsorbed equally and dispersively on the treated SF fiber surface. The HAp content in the composite was 4.554 wt% +/- 0.098 (n = 4), confirmed by thermogravimetry (TG). This synthetic system requires no heat to connect HAp to SF and is useful when applying to non-heat-resistant polymers. The L-929 cell-adhesion test shows that the HAp/SF composite improves bioactivity compared to the original SF.
New segmented polyurethanes (SPUs) containing poly(butadiene) (PBD) soft segments and phospholipid moieties in the main chains and long-chain alkyl groups in the side chains were synthesized. The phospholipid moieties include bis [2-(2-hydroxyethyldimethylammonio)The bulk characterization of synthesized SPUs was investigated by infrared (IR) spectroscopy and gel-permeation chromatography (GPC ). The mechanical properties were evaluated by dynamic viscoelasticity and tensile measurements. The existence of phospholipid analogous groups on the surface of these SPUs was revealed by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy ( XPS) and contact angle measurements. The blood compatibilities of the new polymers were evaluated by platelet rich plasma (PRP) contact studies and viewed by scanning electron microscopy (SEM ) using medical grade BioSpanA and non-phospholipid polyurethane as references. These new materials have good surfaces in terms of platelet adhesion, and the morphology of adhered platelets undergoes a relatively low degree of variation. separation between hard and soft segments. Moreover, these
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