I-Cheng Chen | Texas A&M University (original) (raw)
Address: College Station, Texas, United States
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The contamination of the environment with traditional therapeutics due to metabolic excretion, im... more The contamination of the environment with traditional therapeutics due to metabolic excretion, improper disposal, and industrial waste has been well-recognized. However, knowledge of the environmental distribution and fate of emerging classes of nanomedicine is scarce. This work investigates the effect of surface chemistry of polymeric nanoparticulate drug delivery systems (PNDDS) on their adsorption dynamics and transport in the vicinity of environmentally relevant surfaces for a concentration comparable with hospital and pharmaceutical manufacturing effluents. To this end, five different types of paclitaxel-based nanomedicine having different polymer stabilizers were employed. Their transport behavior was characterized via quartz crystal microbalance, sand column, spectrofluorometry, and dynamic light scattering techniques. PNDDS having positive zeta-potential displayed strong adsorption onto silica surfaces and no mobility in porous media of quartz sand, even in the presence of humic acid. The mobility of negatively charged PNDDS strongly depended on the amount and type of salt present in the aqueous media: Without any salt, such PNDDS demonstrated no adsorption on silica surfaces and high levels of mobility in sand columns. The presence of CaCl2 and CaSO4, even at low ionic strengths (i.e. 10 mM), induced PNDDS adsorption on silica surfaces and strongly limited the mobility of such PNDSS in sand columns.
Chemistry - An Asian Journal, 2011
Clusters are important in bridging the gap between individual molecules in the gas phase and clos... more Clusters are important in bridging the gap between individual molecules in the gas phase and closely interacting molecules in condensed phases. The size of a cluster is a basic parameter that a researcher would like to control or measure. Whereas the size determination of ionic clusters is rather straightforward, determination of the size of a neutral cluster is much more difficult. Only a few methods are available for the size determination of a neutral cluster beam, including: 1) momentum transfer in crossed-beam scattering, 2) diffraction from a transmission grating, and 3) high-resolution spectroscopy. Ozone is not only a crucial molecule in our atmosphere but also a benchmark molecule in photochemistry and photophysics. Theoretical studies on its photodissociation were recently reviewed by Grebenshchikov et al. Although quite a few excited states and complicated non-adiabatic couplings are involved, high-level theoretical calculations can describe the relevant experimental observables of ozone such as its absorption spectrum, product distributions, etc. The detailed information about the ozone molecule may offer a good starting point for investigations of ozone clusters.
We report a novel approach that is based on the complexation and supramolecular assembly of an am... more We report a novel approach that is based on the complexation and supramolecular assembly of an amino-amide and maleic acid to control viscosity of aqueous displacement fluids. It is shown that the addition of only 2 wt% of adaptable amphiphile/maleic acid into water increases the viscosity of water by a factor of 4.5x105. This superior viscosity behavior is ascribed to the formation and entanglements of layered cylindrical supramolecular assemblies with diameters of several hundred nanometers. Furthermore, the viscosity of the amphiphile solution can be increased 12 times by changing pH from 4 to 8 in a reversible manner. Such a property can be very beneficial for oil-recovery applications when the injectivity becomes a limitation. In addition, the use of switchable viscosity can reduce the energy cost associated with pumping large volumes of viscous displacement fluids. We also demonstrate the proof of concept for the use of adaptable amphiphile solutions in enhanced oil recovery (EOR) as oil-displacement fluids through column experiments. Overall, this study shows that pH-switchable supramolecular assemblies have very intriguing properties that can significantly affect EOR technologies.
The contamination of the environment with traditional therapeutics due to metabolic excretion, im... more The contamination of the environment with traditional therapeutics due to metabolic excretion, improper disposal, and industrial waste has been well-recognized. However, knowledge of the environmental distribution and fate of emerging classes of nanomedicine is scarce. This work investigates the effect of surface chemistry of polymeric nanoparticulate drug delivery systems (PNDDS) on their adsorption dynamics and transport in the vicinity of environmentally relevant surfaces for a concentration comparable with hospital and pharmaceutical manufacturing effluents. To this end, five different types of paclitaxel-based nanomedicine having different polymer stabilizers were employed. Their transport behavior was characterized via quartz crystal microbalance, sand column, spectrofluorometry, and dynamic light scattering techniques. PNDDS having positive zeta-potential displayed strong adsorption onto silica surfaces and no mobility in porous media of quartz sand, even in the presence of humic acid. The mobility of negatively charged PNDDS strongly depended on the amount and type of salt present in the aqueous media: Without any salt, such PNDDS demonstrated no adsorption on silica surfaces and high levels of mobility in sand columns. The presence of CaCl2 and CaSO4, even at low ionic strengths (i.e. 10 mM), induced PNDDS adsorption on silica surfaces and strongly limited the mobility of such PNDSS in sand columns.
Chemistry - An Asian Journal, 2011
Clusters are important in bridging the gap between individual molecules in the gas phase and clos... more Clusters are important in bridging the gap between individual molecules in the gas phase and closely interacting molecules in condensed phases. The size of a cluster is a basic parameter that a researcher would like to control or measure. Whereas the size determination of ionic clusters is rather straightforward, determination of the size of a neutral cluster is much more difficult. Only a few methods are available for the size determination of a neutral cluster beam, including: 1) momentum transfer in crossed-beam scattering, 2) diffraction from a transmission grating, and 3) high-resolution spectroscopy. Ozone is not only a crucial molecule in our atmosphere but also a benchmark molecule in photochemistry and photophysics. Theoretical studies on its photodissociation were recently reviewed by Grebenshchikov et al. Although quite a few excited states and complicated non-adiabatic couplings are involved, high-level theoretical calculations can describe the relevant experimental observables of ozone such as its absorption spectrum, product distributions, etc. The detailed information about the ozone molecule may offer a good starting point for investigations of ozone clusters.
We report a novel approach that is based on the complexation and supramolecular assembly of an am... more We report a novel approach that is based on the complexation and supramolecular assembly of an amino-amide and maleic acid to control viscosity of aqueous displacement fluids. It is shown that the addition of only 2 wt% of adaptable amphiphile/maleic acid into water increases the viscosity of water by a factor of 4.5x105. This superior viscosity behavior is ascribed to the formation and entanglements of layered cylindrical supramolecular assemblies with diameters of several hundred nanometers. Furthermore, the viscosity of the amphiphile solution can be increased 12 times by changing pH from 4 to 8 in a reversible manner. Such a property can be very beneficial for oil-recovery applications when the injectivity becomes a limitation. In addition, the use of switchable viscosity can reduce the energy cost associated with pumping large volumes of viscous displacement fluids. We also demonstrate the proof of concept for the use of adaptable amphiphile solutions in enhanced oil recovery (EOR) as oil-displacement fluids through column experiments. Overall, this study shows that pH-switchable supramolecular assemblies have very intriguing properties that can significantly affect EOR technologies.