Lectins and/or xyloglucans/alginate layers as supports for immobilization of dengue virus particles

Formation of stable thin films of mixed xyloglucan (XG) and alginate (ALG) onto Si/SiO2 wafers was achieved under pH 11.6, 50 mM CaCl2, and at 70 °C. XG–ALG films presented mean thickness of (16 ± 2) nm and globules rich surface, as evidenced by means of ellipsometry and atomic force microscopy (AFM), respectively. The adsorption of two glucose/mannose-binding seed (Canavalia ensiformis and Dioclea altissima) lectins, coded here as ConA and DAlt, onto XG–ALG surfaces took place under pH 5. Under this condition both lectins present positive net charge. ConA and DAlt adsorbed irreversibly onto XG–ALG forming homogenous monolayers ∼(4 ± 1) nm thick. Lectins adsorption was mainly driven by electrostatic interaction between lectins positively charged residues and carboxylated (negatively charged) ALG groups.Adhesion of four serotypes of dengue virus, DENV (1–4), particles to XG–ALG surfaces were observed by ellipsometry and AFM. The attachment of dengue particles onto XG–ALG films might be mediated by (i) H bonding between E protein (located at virus particle surface) polar residues and hydroxyl groups present on XG–ALG surfaces and (ii) electrostatic interaction between E protein positively charged residues and ALG carboxylic groups. DENV-4 serotype presented the weakest adsorption onto XG–ALG surfaces, indicating that E protein on DENV-4 surface presents net charge (amino acid sequence) different from E proteins of other serotypes. All four DENV particles serotypes adsorbed similarly onto lectin films adsorbed. Nevertheless, the addition of 0.005 mol/L of mannose prevented dengue particles from adsorbing onto lectin films. XG–ALG and lectin layers serve as potential materials for the development of diagnostic methods for dengue.