School of Chemistry - Research Publications
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ItemElectrochemical investigation of the interaction between lysozyme-shelled microbubbles and vitamin C(SPRINGER HEIDELBERG, 2013-06)We report loading of vitamin C (ascorbic acid) on to lysozyme-shelled microbubbles. The interaction between lysozyme-shelled microbubbles and vitamin C was studied by use of cyclic and differential pulse voltammetry, zeta potential measurements, and scanning electron microscopy. The effect of microbubbles on electrochemical measurement of ascorbic acid was evaluated. The linear range for ascorbic acid obtained for differential pulse measurement in the presence of 1 mg mL(-1) microbubbles was 1-50 μmol L(-1) (y = 0.067x + 0.130, r(2) = 0.995), with a detection limit of 0.5 μmol L(-1). The experimental conditions, i.e., pH and ionic strength, were optimized to improve the interaction between ascorbic acid and lysozyme-shelled microbubbles. The results were satisfactory when the interaction was performed for 1 h in aqueous solution at pH 6. The amount of vitamin C loaded on the microbubbles (90% of the analyte added, RSD(inter-expt.) = 3%, n = 6) and the stability of microbubbles-ascorbic acid complex (until 72 h at 25 °C) were also evaluated by use of differential pulse voltammetry and zeta potential measurements.
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ItemMechanical Characterization of Ultrasonically Synthesized Microbubble Shells by Flow Cytometry and AFM(AMER CHEMICAL SOC, 2013-11-13)The mechanical properties of the shell of ultrasonically synthesized lysozyme microbubbles, LSMBs, were evaluated by acoustic interrogation and nanoindentation techniques. The Young's modulus of LSMBs was found to be 1.0 ± 0.3 MPa and 0.6 ± 0.1 MPa when analyzed by flow cytometry and AFM, respectively. The shell elasticity and Young's modulus were not affected by the size of the microbubbles (MBs). The hydrogel-like protein shell of LSMBs offers a softer, more elastic and viscous interface compared to lipid-shelled MBs. We show that the acoustic interrogation technique is a real-time, fast, and high-throughput method to characterize the mechanical characteristics of air-filled microbubbles coated by a variety of materials.