Statistical Associating Fluid Theory Coupled with Restrictive Primitive Model Extended to Bivalent Ions. SAFT2: 1. Single Salt + Water Solutions

Statistical associating fluid theory coupled with the restricted primitive model is extended to multivalent ions by relaxing the range of the square-well width parameter, which leads to a new dispersion term approximation and calls for a new set of salt and ion parameters. This new approximation, referred to as SAFT2, requires a single set of parameters derived from the salt (mean ionic) activity coefficients and liquid densities of single-salt solutions for five cations (Li(+), Na(+), K(+), Ca(2+), Mg(2+)), six anions (Cl(-), Br(-), I(-), NO(3)(-), SO(4)(-2), HCO(3)(-)), and 24 salts. These parameters, in turn, are shown to predict the osmotic coefficients for single salt + water solutions.

Statistical Associating Fluid Theory Coupled with Restrictive Primitive Model Extended to Bivalent Ions. SAFT2: 2. Brine/Seawater Properties Predicted

Statistical associating fluid theory coupled with restricted primitive model (SAFT2) represents the properties of aqueous multiple-salt solutions, such as brine/seawater. The osmotic coefficients, densities, and vapor pressures are predicted without any additional parameters using the salt hydrated diameters obtained for single-salt solutions. For a given ion composition of brine, the predicted vapor pressure, osmotic coefficient, activity of water, and density are found to agree with the experimental data.

Anticancer efficacies of cisplatin-releasing pH-responsive nanoparticles

The objective of these investigations was to test the hypothesis that a rapid cytoplasmic release profile from nanoparticles would potentiate the anticancer activity of cisplatin. Cisplatin-loaded nanoparticles with pH-responsive poly[2-(N,N-diethylamino)ethyl methacrylate] (PDEA) cores were synthesized from PDEA-block-poly(ethylene glycol) (PDEA-PEG) copolymer by using a solvent-displacement (acetone-water) method. Nanoparticles with pH-nonresponsive poly(epsilon-caprolactone) (PCL) cores made from PCL-block-PEG (PCL-PEG) were used for comparison. Nanoparticle sizes, zeta potentials, drug-loading capacities, and pH responsiveness were characterized. The cellular uptakes and localization in lysosomes were visualized by using confocal fluorescence microscopy. Cytostatic effects of free and encapsulated cis-diammineplatinum(II) dichloride (cisplatin) toward human SKOV-3 epithelial ovarian cancer cells were estimated by using the MTT assay. Intraperitoneal tumor responses to cisplatin and cisplatin/PDEA-PEG were evaluated in athymic mice at 4-6 weeks postinoculation of SKOV-3 cells. PDEA-PEG nanoparticles dissolved at pH < 6 and rapidly internalized and transferred to lysosomes; it therefore was predicted that the PDEA nanoparticles would rapidly release cisplatin into cytoplasm upon integration into acidic lysosomes and thereby overwhelm the chemoresistant properties of SKOV-3 cells. Indeed, relative proportions of viable cells were diminished to a greater extent by exposure in vitro to fast-releasing nanoparticles compared to slow-releasing nanoparticles or an equivalent dose of free cisplatin. Incidences of cellular pyknosis (a morphological indicator of apoptosis) were most evident within intestinal/mesentery tumors of mice treated with cisplatin/PDEA-PEG; tumor burdens were correspondingly reduced.

Highly stable core-surface-crosslinked nanoparticles as cisplatin carriers for cancer chemotherapy

Cisplatin is a potent anticancer drug with low solubility in water. A new type of highly stable polymer micelles, namely core-surface-crosslinked nanoparticles (SCNPs) made from amphiphilic brush copolymers, were evaluated as the carrier of cisplatin. Cisplatin could be loaded in the SCNPs with poly(epsilon-caprolactone) (PCL) cores and hydrophilic poly(ethylene glycol) (PEG) or poly[2-(N,N-dimethylamino)ethyl methacrylate] (PDMA) shells with high loading efficiency (approximately 90%). In vitro cellular uptake experiments indicated that both SCNPs could be easily taken up by SKOV-3 ovarian cancer cells. Both cell proliferation assay and IC50 measurements indicated that cisplatin encapsulated in the SCNPs had much enhanced cytotoxicity to the cancer cells compared to free cisplatin. The positive charges on the PCL/PDMA SCNPs promoted the cellular internalization of the nanoparticles, resulting in higher cytotoxicity of cisplatin in these SCNPs. The IC50 of the cisplatin encapsulated in PCL/PDMA SCNPs was as low as 0.01 microg/mL, lower than that of cisplatin in PCL/PEG SCNPs and free cisplatin.

Enhanced stability of core-surface cross-linked micelles fabricated from amphiphilic brush copolymers

"Stealth" nanoparticles made from polymer micelles have been widely explored as drug carriers for targeted drug delivery. High stability (i.e., low critical micelle concentration (CMC)) is required for their intravenous applications. Herein, we present a "core-surface cross-linking" concept to greatly enhance nanoparticle's stability: amphiphilic brush copolymers form core-surface cross-linked micelles (nanoparticles) (SCNs). The amphiphilic brush copolymers consisted of hydrophobic poly(epsilon-caprolactone) (PCL) and hydrophilic poly(ethylene glycol) (PEG) or poly(2-(N,N-dimethylamino)ethyl methacrylate) (PDMA) chains were synthesized by macromonomer copolymerization method and used to demonstrate this concept. The resulting SCNs were about 100 times more stable than micelles from corresponding amphiphilic block copolymers. The size and surface properties of the SCNs could be easily tailored by the copolymer's compositions.

Poly(ionic liquid)s: a new material with enhanced and fast CO2 absorption

Novel sorbent and membrane materials for CO2 separation, poly(ionic liquid)s made from ionic liquid monomers, poly[p-vinylbenzyltrimethyl ammonium tetrafluoroborate](P[VBTMA][BF4]) and poly[2-(methacryloyloxy)ethyltrimethylamnonium tetrafluoroborate](P[MATMA][BF4]) have absorption capacities 7.6 and 6.0 times of those of room-temperature ionic liquids, e.g.[bmim][BF4], respectively, with reversible and fast sorption and desorption.