School of Chemistry - Research Publications
Permanent URI for this collection
Search Results
1 - 4 of 4
-
ItemUltrasound-Assisted Synthesis of Cross-Linked Poly(ethylene glycol) Nanostructures with Hydrophobic Core and Hydrophilic Shell(WILEY-V C H VERLAG GMBH, 2018-12)Abstract One‐pot synthesis of polymeric nanostructures, by using ultrasound without adding initiators and surfactants, is a straightforward approach that has attracted significant attention in polymer science. In this study, the ultrasonic polymerization technique is employed to synthesize poly(ethylene glycol) based nanoparticles with a hydrophobic core and a hydrophilic shell. Interfacial polymerization is performed using an oil‐in‐water emulsion containing oligo (ethylene glycol) methyl ether methacrylate as a water‐soluble monomer, and ethylene glycol dimethacrylate acting as an oily‐cross‐linker phase. Both the radicals and physical effects generated by acoustic cavitation are crucial to conduct this surfactant and initiator‐free process and obtain uniform nanoparticles endowed with a hydrophobic core and hydrophilic shell. It is shown that the nanoparticle's core can be loaded with hydrophobic compounds. This technique can be applied to different monomers containing various functional moieties such as amines and carboxyl groups to obtain multifunctional nanoparticles.
-
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.
-
ItemMolecular properties of lysozyme-microbubbles: towards the protein and nucleic acid delivery(SPRINGER WIEN, 2012-08)Microbubbles (MBs) have specific acoustic properties that make them useful as contrast agents in ultrasound imaging. The use of the MBs in clinical practice led to the development of more sensitive imaging techniques both in cardiology and radiology. Protein-MBs are typically obtained by dispersing a gas phase in the protein solution and the protein deposited/cross-linked on the gas-liquid interface stabilizes the gas core. Innovative applications of protein-MBs prompt the investigation on the properties of MBs obtained using different proteins that are able to confer them specific properties and functionality. Recently, we have synthesized stable air-filled lysozyme-MBs (LysMBs) using high-intensity ultrasound-induced emulsification of a partly reduced lysozyme in aqueous solutions. The stability of LysMBs suspension allows for post-synthetic modification of MBs surface. In the present work, the protein folded state and the biodegradability property of LysMBs were investigated by limited proteolysis. Moreover, LysMBs were coated and functionalized with a number of biomacromolecules (proteins, polysaccharides, nucleic acids). Remarkably, LysMBs show a high DNA-binding ability and protective effects of the nucleic acids from nucleases and, further, the ability to transform the bacteria cells. These results highlight on the possibility of using LysMBs for delivery of proteins and nucleic acids in prophylactic and therapeutic applications.
-
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.