ABSTRACT
Biofilm formed by Candida albicans on latex silicone surfaces was characterized by instrumental techniques such as fluorescence microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy. The growth and viability of C. albicans on the biofilm formed were described using different kinetic rate equations. C. albicans biofilm has a complex and heterogenous structure with hyphal elements and yeast cells entrenched within a polysaccharide matrix. Spectroscopic studies revealed specific stretching frequencies of O-H, C-O, and C=O which can be attributed to the presence of some functionalities in the biofilm formed by C. albicans. Viability of C. albicans behaved in accordance with the first-order kinetic equation on the first 48 h, then shifted to a second-order kinetic equation until the 72 h, and had a doubling time of 70 h. Information on model biofilms with emphasis on growth rates and morphogenesis, structural organization, and physicochemical characteristics can possibly explain resistance to some antifungal treatments and subsequent synthesis of newer generation drugs for fungal biofilm-related infections.
ABSTRACT
Adsorption isotherm and thermodynamic profile of hexavalent chromium onto lumbang (Aleurites moluccana) activated carbon chitosan composite crosslinked with epichlorohydrin were studied. The optimum conditions were identified at pH 3, contact time of 75 min, adsorbent dose of 3 g/L, initial concentration of 60 ppm, and 30ºC temperature resulted to a removal efficiency of 93%. The composite has a round and elliptical adsorption sites, contains –OH and –NH2 functional groups, and has increased stability with epichlorohydrin crosslinking. The adsorption process is best characterized by the Langmuir isotherm suggesting a monolayer adsorption nature of Cr(VI). The adsorption kinetics obeyed the pseudo-second order model and the adsorption process is exothermic. The investigated adsorption phenomenon described a chemisorption process, with 21.32 kJ mol-1 mean free energy, due to the functional groups identified and the high porosity of the adsorbent surfaces.