1 July 2011 Effects of sodium chloride on the properties of chlorophyll a submonolayer adsorbed onto hydrophobic and hydrophilic surfaces using broadband spectroscopy with single-mode integrated optical waveguides
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Abstract
In this work, we experimentally investigated the effects of sodium chloride on the molar absorptivity and surface density of a submonolayer of chlorophyll a adsorbed onto hydrophilic and hydrophobic solid/liquid interfaces. Those investigations were made possible by a broadband spectroscopic platform based on single-mode, integrated optical waveguides, which allows for extremely sensitive spectroscopic detection of analytes immobilized at submonolayer levels. Chlorophyll a with a constant bulk concentration (1.4 μM) was dissolved in phosphate buffer solutions (7 mM) of neutral pH, but with different sodium chloride concentrations. For a buffer solution of 1 mM of sodium chloride, the measured surface density of chlorophyll a was 0.209 pmol/cm2 for a hydrophilic and 0.125 pmol/cm2 for a hydrophobic surface. For a phosphate buffer solution of 10 mM of sodium chloride, the measured surface density of chlorophyll a was 0.528 pmol/cm2 for a hydrophilic and 0.337 pmol/cm2 for a hydrophobic surface. Additionally, a hypsochromic shift of the Soret band was observed for the adsorbed pigment in correlation with an increase in buffer ionic strength. The adsorption of chlorophyll a onto different surfaces can play an important role to elucidate several processes found in nature and provide a rationale for bio-inspired new material technologies.
© (2011) Society of Photo-Optical Instrumentation Engineers (SPIE)
Rodrigo S. Wiederkehr, Rodrigo S. Wiederkehr, Sergio B. Mendes, Sergio B. Mendes, Geoffrey C. Hoops, Geoffrey C. Hoops, } "Effects of sodium chloride on the properties of chlorophyll a submonolayer adsorbed onto hydrophobic and hydrophilic surfaces using broadband spectroscopy with single-mode integrated optical waveguides," Optical Engineering 50(7), 071109 (1 July 2011). https://doi.org/10.1117/1.3564421 . Submission:
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