Biocompatibility control

An ideal scaffold should possess excellent biocompatibility, controllable biodegradability and suitable mechanical characteristics. Several studies have shown that nanofibrous scaffolds can enhance cellular responses like cell adhesion and cell phenotype maintenance. Electrospun PCL nanofibrous scaffolds can be fabricated in the laboratory for the treatment of partial or full thickness skin defects. These nanofibrous wound dressings, due to their porosity and inherent properties might... 

Langer, R., and Moses, M., 1991, Biocompatible controlled release polymers for delivery of polypeptides and growth factors, J. Cell. Biochem. 45 340-345. 

L. Grehan, J.A. Killion, D.M. Devine, E.K. Kenny, S. Devery, C.L. Higginbotham, and L.M. Geever, The development of hot melt extruded biocompatible controlled release drug delivery devices, Int J Polym Mater, 63 (9), 476-485,2014. 

Recently, for the example ofpoly(3-hydroxybutyrate) (PHB) and a number of its composites [14-16] we have studied physical-chemical, dynamic and transport characteristics of macroscopic biodegradable matrices and microparticles of PHB which were designed for controlled dmg release [16, 17]. High biocompatibility, controlled biodegradation and appropriate mechanical properties allow one to consider this biopolymer as one of the most promising biomedical polymers. Besides therapeutical aims, PHB is widely used as bone implants, nervous conduits, matrices in cell engineering, filters and membranes, in cardiology and in the other areas [14,18,19]. 

Investigations on biocompatible hydrogels based exclusively on polysaccharide chains were reported chitosan was linked with dialdehyde obtained from scleroglucan by controlled periodate oxidation [218]. The reaction took... 

In vivo biocompatibility was assessed through subcutaneous implantation in Sprague-Dawley rats. PLGA was used as a control polymer. PGS and PLGA implants with the same surface area/volume ratio were implanted in dorsal subcutaneous pockets. A fibrous capsule around PGS (45 pm thick after 35 days implantation) appeared later than that around PLGA (140 pm thick after 14 days implantation). After 60 days of implantation, the implant was completely absorbed with no signs of granulation or scar formation. ... 

A surface is that part of an object which is in direct contact with its environment and hence, is most affected by it. The surface properties of solid organic polymers have a strong impact on many, if not most, of their apphcations. The properties and structure of these surfaces are, therefore, of utmost importance. The chemical stmcture and thermodynamic state of polymer surfaces are important factors that determine many of their practical characteristics. Examples of properties affected by polymer surface stmcture include adhesion, wettability, friction, coatability, permeability, dyeabil-ity, gloss, corrosion, surface electrostatic charging, cellular recognition, and biocompatibility. Interfacial characteristics of polymer systems control the domain size and the stability of polymer-polymer dispersions, adhesive strength of laminates and composites, cohesive strength of polymer blends, mechanical properties of adhesive joints, etc. 

Brem, H., Kader, A., Epstein, J. I., Tamargo, R., Domb, A., Danger, R., and Leong, K., Biocompatibility of bioerodible controlled release polymers in the rabbit brain. Selective Caacer Therapeutics. 5, 55-65, 1989. 

In order to test the tissue compatibility of tyrosine-derived poly-(iminocarbonates), solvent cast films of poIy(CTTH) were subcutaneously implanted into the back of outbread mice. In this study, conventional poly(L-tyrosine) served as a control (42). With only small variations, the experimental protocol described for the biocompatibility testing of poly(N-palmitoylhydroxyproline ester) (Sec. III. 

In order to enhance the stability of hposomes and to provide a biocompatible outermost surface shucture for controlled immobihzation (see Section IV), isolated monomeric and oligomeric S-layer protein from B. coagulans E38/vl [118,123,143], B. sphaericus CCM 2177, and the SbsB from B. stearothermophilus PV72/p2 [119] have been crystallized into the respective lattice type on positively charged liposomes composed of DPPC, HD A, and cholesterol. Such S-layer-coated hposomes are spherical biomimetic structures (Fig. 18) that resemble archaeal ceUs (Fig. 14) or virus envelopes. The crystallization of S-... 

Biocompatibility. The analysis of polymer implants has been employed using FTIR spectroscopy to elucidate the long-term biocompatibility and quality control of biomedical materials. This method of surface analysis allows the determination of the specific molecular composition and structures most appropriate for long-term compatibility in humans. 

Initial tests in the rat revealed a high degree of tissue compatibility of Dat-Tyr-Hex derived polymers. More detailed tests are now in progress. In addition, tyrosine derived polymers are currently being evaluated in the formulation of an intracranial controlled release device for the release of dopamine, in the design of an intraarterial stent (to prevent the restenosis of coronary arteries after balloon angioplasty), and in the development of orthopedic implants. The use of tyrosine derived polymers in these applications will provide additional data on the biocompatibility of these polymers. 

The effect of the material on cellular metabolism is also an important measure of biocompatibility. To determine such effects, cultured ex vivo cells can be exposed to the polymer and the growth rates compared to controls [216,217], The metabolic function of the cells can be tested by assay for production of a marker enzyme. An additional advantage of this type of test is that it avoids the use of live animals. 

---