RESUMO
We investigated polysaccharide films obtained by simultaneous and alternate spraying of a chitosan (CHI) solution as polycation and hyaluronic acid (HA), alginate (ALG), and chondroitin sulfate (CS) solutions as polyanions. For simultaneous spraying, the film thickness increases linearly with the cumulative spraying time and passes through a maximum for polyanion/CHI molar charge ratios lying between 0.6 and 1.2. The size of polyanion/CHI complexes formed in solution was compared with the simultaneously sprayed film growth rate as a function of the polyanion/CHI molar charge ratio. A good correlation was found. This suggests the importance of polyanion/polycation complexation in the simultaneous spraying process. Depending on the system, the film topography is either liquid-like or granular. Film biocompatibility was evaluated using human gingival fibroblasts. A small or no difference is observed in cell viability and adhesion between the two deposition processes. The CHI/HA system appears to be the best for cell adhesion inducing the clustering of CD44, a cell surface HA receptor, at the membrane of cells. Simultaneous or alternate spraying of CHI/HA appears thus to be a convenient and fast procedure for biomaterial surface modifications.
Assuntos
Alginatos/química , Materiais Biocompatíveis/química , Quitosana/química , Sulfatos de Condroitina/química , Ácido Hialurônico/química , Poliaminas/química , Polímeros/química , Adsorção , Adesão Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Engenharia Química , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Gengiva/citologia , Gengiva/efeitos dos fármacos , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Humanos , Receptores de Hialuronatos/biossíntese , Microscopia de Força Atômica , Polieletrólitos , Soluções , Propriedades de SuperfícieRESUMO
Proper staining of grids is critical for transmission electron microscopy (TEM). Staining must be done as quickly as possible using minimal reagents and with consideration for the environment. We developed a new device for efficient staining of multiple TEM grids. We studied reagent evaporation, rinsing volume, flow rate and re-use of uranyl acetate, and provide here a procedure for efficient staining using the new device. Our device permits TEM grids to be stained with less reagent than alternative staining apparatuses; staining requires a total volume of 260 µl for five grids. Reagent evaporation is less than 6% even if used at 37° C. Moreover, our staining apparatus reduces chemical waste and shortens experiment time by staining several grids simultaneously. Our staining device is a compromise between time-consuming single grid processing and expensive commercial devices that consume large amounts of reagents.