Epidermis of Cereus hildmannianus as a biomimetic scaffold for tissue engineering.

A thin plastic-like film separated from the epidermis of Cereus hildmannianus has excellent tensile strength, resistance to water and high antimicrobial activity and supports the growth of mouse fibroblast cells. Cactuses are one of the most under explored plant species with high potential for food, materials, pharmaceutical and other applications. Although studies have shown the ability of cactuses to be used for food, as a source for fibers, as reinforcement for composites and other applications, the role of individual layers and their properties has been studied to a limited extent. In this paper, a thin translucent layer was separated from the epidermis of C. hildmannianus and studied for its composition, structure and properties. The layer is composed of about 73% cellulose and 2% lignin and morphologically, shows surface with uneven and serrated edges. Films with length of up to 36 cm, strength of 6.8 MPa and elongation of 2.5% could be peeled from the cactus suggesting their suitability for food packaging and other applications. X-ray diffraction patterns and FTIR spectrums indicated that the films are similar to that of cellulose and major thermal degradation occurred above 280°C. Compared to standards, the cactus films showed about 41% and 44% inhibition against gram positive and gram negative bacteria and 67% inhibition of the common fungal strain (A. niger). Films showed high stability in water and to common chemicals. When used as substrates for mouse fibroblast cell growth, no cytotoxicity was observed and the cactus peel supported the attachment and proliferation of cells demonstrating potential to be used as a biomaterial for tissue engineering applications.

Properties of chitin and chitosan extracted from silkworm pupae and egg shells.

Chitin and chitosan from silkworm pupae and egg shells show distinct properties with excellent antimicrobial properties and cytocompatiblity. Spent silkworm pupae and hatched egg shells are discarded as waste but contain valuable carbohydrates, proteins and lipids. Chitosan has excellent antimicrobial properties and is widely used for food, medical and biotechnological applications. In this paper, we report the properties of chitin and chitosan from silkworm pupae and egg shells in comparison to commercially available chitosan. Defatted and deproteinated pupae and shells were demineralized and later deacetylated to form chitosan. Thermal behavior, physical structure, antimicrobial activity and ability to support the attachment and growth of NIH3T3 cells were studied. Chitin and chitosan from both pupae and shells had similar structure and composition. Crystallinity of the pupae chitosan was 48% compared to 38% for egg shell chitosan. Silkworm chitosan showed considerably higher antibacterial and antifungal activity compared to standard. Cells were viable in the presence of pupae and egg shell chitosan in all the concentrations tested. Based on these observations, it can be inferred that silkworm pupae and shells provide a renewable and sustainable source for chitosan with properties suitable for food and medical applications.

Biofibers and biocomposites from sabai grass: A unique renewable resource.

Natural cellulose fibers were extracted from a fast growing perennial grass Eulaliopsis binata (commonly known as Sabai) and characterized for their structure and properties. The untreated sabai grass has been used as reinforcement for polypropylene composites and properties of the composites have been investigated. Although the composition of the sabai grass is typical to other lignocellulosic sources, there is a high content of flavonoids (630 mg/g) and phenols (510 mg/g) which provides high antibacterial, and antifungal properties to the fibers and composites developed. Fiber bundles extracted from the grass had tensile strength of 493 MPa and tensile modulus of 21 GPa, similar to common natural cellulose fibers. Both tensile and flexural properties of polypropylene composites increased with increasing ratio of sabai grass. Polypropylene composites reinforced with sabai grass show high noise insulation and thermal resistance properties suggesting their suitability for automotive and building applications.

Antimicrobial activity of cold and hot successive pseudobulb extracts of Flickingeria nodosa (Dalz.) Seidenf.

Flickingeria nodosa (Dalz.) Seidenf is a medicinally important orchid plant. It is used for the treatment of asthma, bronchitis, throat infections, dermatological infections and also used as blood purifier. Based on its importance the present study was designed to evaluate its antibacterial and antifungal activity against human pathogens with cold and hot successive extracts. The antimicrobial activities of the plant extracts were evaluated against 7 bacterial and 6 fungal strains using well diffusion method on Mueller Hinton agar medium. The cold water extract has antibacterial activity against S. aureus and S. citreus with maximum zone of inhibition. The cold chloroform extract has good antifungal activity against T. mentagrophytes. The plant can be a source material to herbal drug industry since it has some important antimicrobial components in the extracts that can be used for the development of therapeutic phytomedicine.