Galactomannan thin films as supports for the immobilization of Concanavalin A and/or dengue viruses

Abstract

The immobilization of the glucose/mannose-binding lectin from Concanavalia ensiformis seeds (ConA) onto a monolayer made of a galactomannan extracted from Leucaena leucocephala seeds (GML), which was adsorbed onto - amino-terminated surfaces, was investigated by means of ellipsometry and atomic force microscopy. The mean thickness of GML monolayer, which polysaccharide consists of linear 1→4-linked β-D-mannopyranosil units partially substituted at C-6 by α-D-galactopyranosyl units, amounted to (1.5±0.2) nm. ConA molecules adsorbed onto GML surfaces forming (2.0±0.5) nm thick layers. However, in the presence of mannose the adsorption failed, indicating that ConA binding sites were blocked by mannose and were no longer available for mannose units present in the GML backbone. The GML film was also used as support for the adsorption of three serotypes of dengue virus particles (DENV-1, DENV-2 and DENV-3), where DENV-2 formed the thickest film (4±2) nm. The adsorbed layer of DENV-2 onto ConA-covered GML surfaces presented mean thickness values similar to that determined for DENV-2 onto bare GML surfaces. The addition of free mannose units prevented DENV-2 adsorption onto ConA-covered GML films by ~50%, suggesting competition between virus and mannose for ConA binding sites. This finding suggests that if ConA is also adsorbed to GML surface and its binding site is blocked by free mannose, virus particles are able to recognized GML mannose unities substituted by galactose. Interactions between polysaccharides thin films, proteins, and viruses are of great relevance since they can provide basis for the development of biotechnological devices. These results indicate that GML is a potential polysaccharide for biomaterials development, as those could involve interactions between ConA in immune system and viruses.

Bioactive nanocomposites of bacterial cellulose and natural hydrocolloids

“…17,18 Another promising application of galactomannans is their adsorption on solid substrates for immobilization of biomolecules, which can allow the development of biosensors. 19,20 Hyaluronic acid (HA) is a polysaccharide with widespread medical applications. As a component of an extracellular matrix, it can be used in ophthalmic surgeries, 21 tissue engineering 22 and as a temporary substitute for skin in burn therapy.…”

The Characterisation and Quantification of Immobilised Concanavalin A on Quartz Surfaces Based on The Competitive Binding to Glucose and Fluorescent Labelled Dextran

“…Con A was added at a concentration of 1 mg mL −1 in an aqueous 20 mM MOPS buffer of pH 5.5 containing 10 mM CaCl 2 and 10 mM MnCl 2 . The Ca 2+ and Mn 2+ ions play the role of co-factors [38] required to activate the protein for glucose binding. The MOPS buffer containing Con A was further diluted 10-fold in 50 mM Boric acid to a final concentration of 0.1 mg mL −1 protein.…”

Investigating a galactomannan gel obtained from Cassia grandis seeds as immobilizing matrix for Cramoll lectin

“…A potential explanation for the decay on G and G moduli for our immobilizing gel matrix comes from Valenga et al [13] study on the immobilization of the lectin extracted from Concanavalia ensiformis seeds, also known as ConA, onto a monolayer made of a galactomannan extracted from Leucaena leucocephala seeds. They suggested that because the galactomannan backbone is ␤-dmannose (1 → 4) linkage and some units at the C-6 position carries ␣-d-galactose units, the recognition of ConA might be for OH groups at the C-3 and C-6 position for the mannose units not substituted.…”

“…Many studies have reported the potential use of galactomannans as thickeners [5], part of mixed systems such as hydrogels [6], emulsion stabilizers in the preparation of films [7] and edible films themselves with enhanced barrier as well as mechanical properties that extend and improve food shelf-life [8,9]. It is also important to highlight the application of galactomannans in the cosmetic industry [10] and as matrix for immobilization of certain biomolecules [11][12][13][14].…”