**6. References**


while Zn2+ was moderately positive. All of the binary combinations were moderately positive except for NiZn, which was moderately negative, and ZnCd, which was only slightly positive. The tertiary combinations were as on the native biomaterial, all moderately negative. Again, this only reflects relative inhibition of metal ion binding. The data listed in Table 7a reveals single metal bound values were all about 25 mol g-1 (average 24.5). These are compared to those for the binary combinations which ranged from 30 – 32 mol g-1 (average 31.0), an increase of 6. Similarly to the native material, the tertiary combinations ranged from 29 – 39 mol g-1 (average 31.1), a slight increase which may not be statistically significant. This again suggested that some degree of cooperativity in binding with the

Carboxylate groups are important functionalities for metal ion adsorption for the biomaterial *Datura innoxia*. Esterification of these functionalities was observed to reduce metal binding capacity 30-40%. Three metals of similar binding affinity to the biomaterial (Cd2+, Ni2+, and Zn2+) were exposed sequentially to both the native esterified biomaterials immobilized within a polysilicate matrix. Removal of surface carboxylates significantly impacted the binding of each metal ion and the impact of each metal bound on the binding of the others. A model involving at least 16 binding sites for these metal ions revealed a majority of binding to involve species-independent or common sites and the presence of

The authors wish to acknowledge the financial support of the Waste-management Education and Research Consortium funded by the US Department of Energy through New

Davis, T.A.; Volesky, B.; Mucci, (2003) A. A Review of the Biochemistry of Heavy Metal

Drake, L.R.;.Rayson, G. D. (1996) Plant Materials for Metal Selective Binding and

Drake, L.R.; Lin, S.; Rayson, G.D. (1996) Chemical Modification and Metal Binding Studies

Drake, L.R.; Hensman, C.E.; Lin, S.; Rayson, G.D.; Jackson, P.J. (1997) Characterization of

Biosorption by Brown Algae. *Water Research* vol.37, No. 18 (November 2003) pp.

Preconcentration *Analytical Chemistry*, vol. *68*, no. 1 ( Jauary 1996), pp. 22A-27A.

of *Datura innoxia*. *Environmental Science and Technology*, vol. *30*, no. 1 (January 1996)

Metal Ion Binding Sites on *Datura innoxia* by Using Lanthanide Ion Probe Spectroscopy. *Applied Spectroscopy,* vol. *51*, no. 10 (October 1997) pp. 1476-1483.

primary binding mechanism involving electrostatic attractions.

cooperativity for some metal-ion binding environments

4311-4330 ISSN: 0043-1354.

pp. 110-114. ISSN 0013 936X

ISSN 0003-2700

ISSN 0003-7028

**4. Conclusions** 

**5. Acknowledgements** 

Mexico State University.

**6. References** 


**8** 

*México* 

**Decellularization, Stabilization and** 

*1Universidad Politécnica de Juventino Rosas 2Centro de Investigación Científica de Yucatán* 

**Used as Cardiovascular Biomaterials** 

**Functionalization of Collagenous Tissues** 

Birzabith Mendoza-Novelo1 and Juan Valerio Cauich-Rodríguez2

Cardiovascular diseases are a worldwide problem being a significant cause of morbity and mortality every year. Patients requiring heart valve replacements include those exhibiting degenerative valvular diseases and rheumatic fever. The pathological processes include stenosis, fibrosis, myxoid change and calcification. The fibrosis causes a reaction to normal haemodynamic while the myxoid change reduces tensile strength of the valve due to replacement of dense collagenous tissue by loose tissue rich in glycosaminoglycans. Moreover, these pathologies can be observed in normal valves or fibrotic valves (Lindop,

Fortunately, the development of cardiovascular prostheses, either synthetic or biological, has allowed to increase life expectancy and has improved the quality of life of patient requiring either heart valves (Flanagan & Pandit, 2003; Schoen & Levi, 1999; Vesely, 2005) or vascular grafts (Matsagas et al., 2006; Monn & West, 2008; Schmidt & Baier, 2000). The implant technology for cardiovascular systems made use of raw materials of different origins. For example, metallic materials and synthetic polymers have been widely used in mechanical valves for the replacement of diseased heart valves. However, some complications such as alterations in the hemodynamical function and thrombus formation

Biological prostheses provide some answers to these complications, although the bioprostheses do not fulfil their objectives satisfactorily, since they display others complications once implanted. The complications of tissue valves include calcification, remnant tissue immunogenicity, inflammatory degradation, mechanical damage and lack of repair (Zilla et al., 2008). Therefore, the need for safe, economic, physiologically acceptable

Collagenous tissues are alternative raw materials for the manufacture of medical devices due to their physical and biomechanical properties. These tissues promote cell interactions, exhibit good ion and macromolecular binding capacity in addition to their electrostatic, hemostatical and immunological properties (Li, 2007). Since 1960s, perichardial tissues and the porcine heart valves are two of the most widely used biological tissues in the construction of cardiovascular devices. The introduction of these biological biomaterials was

and viable biomaterial has motivated the modification of collagen-rich tissues.

**1. Introduction** 

have been found (Zilla et al., 2008).

2007).

Xia, H.; Rayson, G.D., (2002) 113Cd NMR Spectrometry Of Cd Binding Sites On Algae And Higher Plant Tissues, *Advances in Environmental Research*, vol. 7, no. 1 (November 2001) pp. 157-167 ISSN: 1093-0191..
