Tuning the In Vivo Transport of Anticancer Drugs Using Renal‐Clearable Gold Nanoparticles

Precise control of in vivo transport of anticancer drugs in normal and cancerous tissues with engineered nanoparticles is key to the future success of cancer nanomedicines in clinics. This requires a fundamental understanding of how engineered nanoparticles impact the targeting‐clearance and permeation‐retention paradoxes in the anticancer‐drug delivery. Herein, we systematically investigated how renal‐clearable gold nanoparticles (AuNPs) affect the permeation, distribution, and retention of the anticancer drug doxorubicin in both cancerous and normal tissues. Renal‐clearable AuNPs retain the advantages of the free drug, including rapid tumor targeting and high tumor vascular permeability. The renal‐clearable AuNPs also accelerated body clearance of off‐target drug via renal elimination. These results clearly indicate that diverse in vivo transport behaviors of engineered nanoparticles can be used to reconcile long‐standing paradoxes in the anticancer drug delivery.     

Optimizing separation conditions for polycyclic aromatic hydrocarbons in micellar electrokinetic chromatography

We report the separation of polycyclic aromatic hydrocarbons (PAHs) using 0.1% poly(ethylene oxide) (PEO) in micellar electrokinetic chromatography (MEKC). In the presence of PEO, adsorption of PAHs on the capillary wall was reduced, leading to better resolution and reproducibility. Effects of tetrapentylammonium iodide (TPAI), dextran sulfate (DS), methanol, and sodium lauryl sulfate (SDS) on the separation of PAHs were elucidated. In terms of resolution and speed, DS, compared to TPAI, is a better additive for separation of PAHs. When using 0.1% PEO solution containing 45% methanol, 50 mM SDS, and 0.02% DS, separation of 10 PAHs containing 2 to 5 benzene rings was accomplished in less than 12 min at 15 kV in a commercial CE system. The method has also been tested for separating seven PAHs with high quantum yields when excited at 325 nm using a He-Cd laser. Unfortunately, separation of the seven PAHs was not achieved and sensitivity diminished under the same conditions. To optimize sensitivity, resolution and speed, a stepwise technique in MEKC has been proposed. The seven PAHs were resolved in 35 min at 15 kV when separation was performed in 0.1% PEO solution containing 35 mM SDS, 40% methanol and 0.02% DS for 2 min, and subsequently in 0.1% PEO solution containing 20 mM SDS, 50% methanol, and 0.02% DS.     

Enzyme-catalyzed transesterification of vinyl esters on cellulose solids

Enzyme-catalyzed transesterification of several cellulose solids in organic media have been investigated. Several protease enzymes were made soluble in organic media through ion-paired enzyme–surfactant complexes. Subtilisin Carsberg was found to be catalytically active in the transesterification of cellulose with vinyl propionate and vinyl acrylate in anhydrous pyridine. The ester carbonyl groups in acylated cellulose derivatives were confirmed by Fourier transform infrared spectroscopy. The surfaces of these cellulose derivatives became hydrophobic as demonstrated by increased water-contact angles. The enzyme-catalyzed transesterification was confirmed to regioselectively target the primary hydroxyl group of cellulose by reactions on specifically substituted cellulose. The cellulose esters from enzyme-catalyzed transesterification could be hydrolyzed partially by the same enzyme in aqueous media, and were thus biodegradable. Surface grafting of cellulose acrylate was demonstrated using azobisisobutyronitrile-initiated polymerization of acrylonitrile in dimethylformamide. Polyacrylonitrile (PAN)-g-cellulose shows a different thermal behavior from cellulose, homopolymer PAN, and PAN/cellulose blends. The grafted PAN on PAN-g-cellulose at a 16% grafting add-on is incapable of cyclization. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1931–1939, 2001     

Synthesis of five-coordinate manganese(I) carbonyl complex [(CO)<Subscript>3</Subscript>Mn (-S,-Se-C<Subscript>6</Subscript>H<Subscript>3</Subscript>-4-Me)]<Superscript>−</Superscript>: influences of non-innocent ligand to the structure,reactivity and electrochemical property

Oxidative addition of Br₂ to [Mn(CO)₅]^? leads to the formation of [(CO)₄MnBr], followed by the ligand exchange of bromide to [S,Se-C₆H₃-4-Me] ₂ ^2? to form complex (CO)₃Mn (µ-? ⁴-SC₆H₃-4-(CH₃)Se-SeC₆H₃-4-(CH₃)S)Mn(CO)₃ (1). A new five-coordinate complex [(CO)₃Mn(-S,-Se-C₆H₃-4-CH₃)]^? (2) can be synthesized through two different routes: (a) oxidative addition of diselenide [HS,Se-C₆H₃-4-Me]₂ to the [Mn(CO)₅]^? followed by deprotonation and ligand dissociation to generate complex 2; (b) reduction of diselenide bonds of complex 1 by [BH₄]^? to produce 2. Drop-wise addition of HBF₄·OEt₂ at 0 °C results in the formation of complex 1. The X-ray analysis shows that complex 2 has relative short Mn–Se and Mn–S bond distances compare to the published structures of cis-[(CO)₄Mn(EPh)₂]^? (E = S and Se; Liaw et al. in J. Chin. Chem. Soc. 43:427–431, 1996; Liaw et al. in Inorg. Chem. 35:2530, 1996). Interestingly, exposure of the coordinated unsaturated complex 2 under CO_(g) atmosphere resulted in complex cis-[(CO)₄Mn(-S,-Se-C₆H₃-4-Me)]^? (3) being formed. After purging the solution of complex 3 with N₂, it was reconverted completely back to complex 2; this observation was characterized by FTIR. The cyclic voltammetry scan of complex 2 shows a quasi-reversible redox couple with E _1/2 = ?1.94 V and I _pa/I _pc = 0.68. Ligand [HS, Se-C₆H₃-4-CH₃]₂ and complexes 1 and 2 are all characterized by IR, UV–Vis, NMR, EA and X-ray single crystal diffraction.     

Optimal ordering and pricing policy for an inventory system with trial periods

It is a business practice that home shopping companies offer a free trial period for their products with a goal of increasing sales. Under this policy, if for any reason customers are not satisfied with the purchase, they can return the product for a refund within the trial period. To develop inventory strategies in such environment, home shopping companies should take the return phenomenon into account so as to increase their profit. This paper considers this phenomenon and develops a seasonal inventory model to deal with the problem. Two scenarios are analyzed. In the first scenario, demand is assumed to be linearly price-dependent while in the second one, it is assumed to be exponentially price-dependent. The purpose of this research is to maximize the total profit over a given planning period by determining the optimal ordering quantity and price. The analytical results demonstrate that the optimal ordering quantity and prices are obtained using closed-form formulas.     

A Lyapunov functional for a stage-structured predator–prey model with nonlinear predation rate

We consider the dynamics of a general stage-structured predator–prey model which generalizes several known predator–prey, SEIR, and virus dynamics models, assuming that the intrinsic growth rate of the prey, the predation rate, and the removal functions are given in an unspecified form. Using the Lyapunov method, we derive sufficient conditions for the local stability of the equilibria together with estimations of their respective domains of attraction, while observing that in several particular but important situations these conditions yield global stability results. The biological significance of these conditions is discussed and the existence of the positive steady state is also investigated.     

Dissipative Nonlinear Evolution Equations and Chaos

In this article we have studied the nonlinear interaction between ellipticity and dissipation in a set of model equations (1.1) and established the relation between this interaction and chaos. In addition to theoretical investigations, extensive numerical simulations with these equations have been made, and different routes to chaos have been found. The numerical studies have revealed the chaotic nature of the solutions.     

Availability Analysis of Repairable <Emphasis Type="Italic">N</Emphasis>-Server <Emphasis Type="Italic">n</Emphasis><Subscript><Emphasis Type="Italic">i</Emphasis></Subscript>-Replicated Systems

We develop an exact closed-form expression for the steady-state availability of a repairable, N-server system in which the ith server contains n _i identical, reconfigurable, breakdown-prone units. Our approach, which follows from the Markov chain balance equations and the recursive properties of Hessenberg matrix determinants, is simpler than previously proposed matrix geometric approaches, and can readily be adapted to the availability analysis of more complicated structures. We illustrate this by computing the steady-state availability of a mixed parallel-serial gracefully degrading replicated system.     

On damping coefficient due to phase transformation

The damping coefficient of capillary waves due to the evaporation-condensation process at the interface of the two phases of a fluid is evaluated. To highlight the mechanism of the effect of heat and mass transfer across the interface between regions of liquid and vapor, potential flow of incompressible fluids are assumed. Thus other mechanisms of damping are neglected. To fascilitate the analysis, the method of multiple-scale is employed in the analysis, even though the problem is linear.     

Automatic knowledge extraction from survey data: learning <Emphasis Type="Italic">M</Emphasis>-of-<Emphasis Type="Italic">N</Emphasis> constructs using a hybrid approach

Data collected from a survey typically consist of attributes that are mostly if not completely binary-valued or binary-encoded. We present a method for handling such data where the underlying data analysis can be cast as a classification problem. We propose a hybrid method that combines neural network and decision tree methods. The network is trained to remove irrelevant data attributes and the decision tree is applied to extract comprehensible classification rules from the trained network. The conditions of the rules are in the form of a conjunction of M-of-N constructs. An M-of-N construct is a rule condition that is satisfied if (at least, exactly, at most) M of the N binary attributes in the construct are present. The effectiveness of the method is illustrated on data collected for a study of global car market segmentation. The results show that besides achieving high predictive accuracy, the method also allows meaningful interpretation of the relationships among the data variables.