Controlling mechanical properties of bio-inspired hydrogels by modulating nano-scale, inter-polymeric junctions

Quinone tanning is a well-characterized biochemical process found in invertebrates, which produce diverse materials from extremely hard tissues to soft water-resistant adhesives. Herein, we report new types of catecholamine PEG derivatives, PEG-NH-catechols that can utilize an expanded spectrum of catecholamine chemistry. The PEGs enable simultaneous participation of amine and catechol in quinone tanning crosslinking. The intermolecular reaction between PEG-NH-catechols forms a dramatic nano-scale junction resulting in enhancement of gelation kinetics and mechanical properties of PEG hydrogels compared to results obtained by using PEGs in the absence of amine groups. Therefore, the study provides new insight into designing new crosslinking chemistry for controlling nano-scale chemical reactions that can broaden unique properties of bulk hydrogels.

Tannage quinonique de la capsule ovigère de la Roussette Scyliorhinus canicula (Linné)

Histochemical and histoenzymological investigations performed on sections of the capsule wall have led to the localisation of the substances involved in the process of quinone tanning. Ultrastructural autoradiography and cytochemical and cytoenzymological techniques applied to the nidamental gland have helped to clarify previous histochemical results and to establish a link between gland secretions and the different capsule layers; a hypothesis concerning the capsule secretion process and its hardening is presented.

Sclerotization of Insect Cuticle in a Cell-Free System

Incubation of deproteinized larval cuticle (chitin flakes) with purified arylphorin (calliphorin) or larval haemolymph of Calliphora vicina resulted in the formation of a chitin-protein complex. Enzymatic oxidation of N-β-alanyldopam ine (NDAB) in the presence of chitin flakes or the chitin-protein complex, resulted in various degrees of cross-linking of NBAD-quinone formed with chitin. This study confirms the involvement of arylphorin in the process of quinone tanning of insect cuticle.

Ultrastructure of the epithelium of the upper ejaculatory duct of the mealworm beetle, Tenebrio molitor

The male mealworm, Tenebrio molitor produces a spermatophore to facilitate transfer of sperm to the female. The wall of the spermatophore is largely produced from the secretions of the paired bean-shaped accessory glands (BAGs). As the cottony pre-spermatophoric mass from the BAGs comes together in the ejaculatory duct where it is molded into the spermatophore, it becomes tougher and more elastic. The mechanisms involved in this stabilization of the wall of the spermatophore were unknown. Mechanisms of stabilization of other acellular structures assembled in extracellular space include quinone-tanning and β-sclerotization in cuticle, shear forces in silk, and pH changes in the spermatophore of Rhodnius. The cells found in the epithelium of the upper ejaculatory duct of the mealworm beetle were examined by transmission electron microscopy for ultrastructural evidence of a role in the stabilization of the spermatophore wall.