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Gamma-Poly(glutamic acid)/Chitosan Composite Scaffolds for Tissue Engineering Applications (2007)

Tsai, Sung Pei ; Hsieh, Chien Yang ; Hsieh, Chung Yu ; [et al.]

s.l. ; Stafa-Zurich, Switzerland

Materials science forum Vol. 539-543 (Mar. 2007), p. 567-572

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ISSN: 1662-9752

Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: The development of tissue engineering provides a novel approach to restore bodilyfunctions by seeding cells onto various scaffolds. Although chitosan is a non-toxic biomaterial, itscytocompatibility still needs to be improved. In this study, gamma-poly(glutamic acid) (γ-PGA) wasblended with chitosan to prepare both dense and porous γ-PGA/chitosan composite scaffolds usingthe freeze-gelation method. This method saves time and energy, and there is less residual solvent.SEM micrographs demonstrated that an interconnected porous structure with a pore size of 30-100micrometer was present in the scaffolds. The hydrophilicity of the scaffolds was significantlyimproved by γ-PGA. Further, the tensile strength of the porous γ-PGA-modified chitosan scaffoldswas about 50% higher than that of the unmodified chitosan scaffolds. The number of osteosarcomacells cultured on the γ-PGA-modified scaffolds was about double that on the unmodified chitosanscaffolds on day 7. Thus, the γ-PGA/chitosan composite scaffolds, due to their better hydrophilicity,cytocompatibility, and mechanical strength, are very promising biomaterials for tissue engineeringapplications. We further demonstrated the use of glutamic acid to enhance the tensile strength ofchitosan-based composite porous scaffolds. The tensile strength of the chitosan/collagen compositescaffolds was increased by more than 2 times with the addition of glutamic acids as cross-linkingbridges. We found that the hepatocytes attached and proliferated well on these composite scaffolds,demonstrating that the glutamic acid modified-chitosan composite scaffolds are also potential tissueengineering biomaterials

Type of Medium: Electronic Resource

URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/14/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.539-543.567.pdf

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Use of low MW polylactic acid and lactide to stimulate growth and yield of soybeans (1996)

Chang, Yaw-Nan ; Mueller, Richard E. ; Iannotti, Eugene L.

Springer

Plant growth regulation 19 (1996), S. 223-232

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ISSN: 1573-5087

Keywords: polylactic acid ; lactide ; lactic acid ; soybeans ; yield ; plant growth regulator

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Polylactic acid (PLA) is an environmentally friendly, degradable polymer which has been suggested for use as a matrix for controlled release of herbicides. The growth stimulation and yield improvement potential of low molecular weight (MW), poly(D,L-lactic acid) and D,L-lactide were evaluated using preplant soil incorporation with soybeans (Glycine max (L.) Merrill). Greenhouse studies confirmed that both lactide and PLA increased soybean leaf area, pod number, bean number and bean and plant dry weight. Soybean seed yield was increased most dramatically (130%; 2.3 fold) by weekly 30 ppm lactide addition and also by single addition of low MW (3500 Daltons) PLA (40.6%; 1.4 fold). Low levels of PLA were stimulatory (15–30 ppm), while higher levels were inhibitory, with some interaction with growth conditions being evident. The stimulatory component was most readily provided by weekly lactide addition, but was also provided by slow-release, hydrolytic breakdown of PLA in the soil, with 3500 Daltons MW being better than higher MW PLA. In field studies at two locations, PLA (16.8 and 45.8 kg ha−1) increased soybean plot yield as much as 18%, being reflected in increases in both growth and per plant yield components (plant dry wt, seed number, seed dry wt, and number of branch pods and seeds). The levels used in field studies were selected to be similar to the level of a typical carrier used in slow release of herbicides. This study suggests that use of PLA as an encapsulation matrix for herbicides could provide reduced environmental impact and improved weed control, while at the same time increasing yield of soybeans through release of a plant growth stimulant in the form of oligomeric or monomeric lactic acid.