Genomics analysis of Drosophila sechellia response to Morinda citrifolia fruit diet.

Drosophila sechellia is an island endemic host specialist that has evolved to consume the toxic fruit of Morinda citrifolia, also known as noni fruit. Recent studies by our group and others have examined genome-wide gene expression responses of fruit flies to individual highly abundant compounds found in noni responsible for the fruit's unique chemistry and toxicity. In order to relate these reductionist experiments to the gene expression responses to feeding on noni fruit itself, we fed rotten noni fruit to adult female D. sechellia and performed RNA-sequencing. Combining the reductionist and more wholistic approaches, we have identified candidate genes that may contribute to each individual compound and those that play a more general role in response to the fruit as a whole. Using the compound specific and general responses, we used transcription factor prediction analyses to identify the regulatory networks and specific regulators involved in the responses to each compound and the fruit itself. The identified genes and regulators represent the possible genetic mechanisms and biochemical pathways that contribute to toxin resistance and noni specialization in D. sechellia.

Assessing the Role of Capping Molecules in Controlling Aggregative Growth of Gold Nanoparticles in Heated Solution.

This report describes findings of an investigation of the role of capping molecules in the size growth in the aggregative growth of pre-formed small-sized gold nanoparticles capped with alkanethiolate monolayers toward monodispersed larger sizes. The size controllability depends on the thiolate chain length and concentration in the thermal solution. The size evolution in solution at different concentrations of alkanethiols is analyzed in relation to adsorption isotherms and cohesive energy. The size dependence on thiolate chain length is also analyzed by considering the cohesive energy of the capping molecules, revealing the importance of cohesive energy in the capping structure. Theoretical and experimental comparisons of the surface plasmonic resonance optical properties have also provided new insights into the mechanism, thus enabling the exploitation of size-dependent nanoscale properties.

Titration of gold nanoparticles in phase extraction.

In the organic-aqueous phase transfer process of gold nanoparticles, there are two types of distinctive interfaces involving hydrophilic and hydrophobic ligands, the understanding of which is important for the design of functional nanomaterials for analytical/bioanalytical applications and the control over the nanoparticles' nanoactivity and nanotoxicity in different phases. This report describes new findings of an investigation of the quantitative aspect of ligand ion pairing at the capping monolayer structure that drives the phase extraction of gold nanoparticles. Alkanethiolate-capped gold nanoparticles of 8 nm diameter with high size monodispersity (RSD ∼ 5%) were first derivatized by a ligand place exchange reaction with 11-mercaptoundecanoic acid to form a mixed monolayer shell consisting of both hydrophobic (-CH3) and hydrophilic (-COOH) groups. It was followed by quantitative titration of the resulting nanoparticles with a cationic species (-NR4(+)) in a toluene phase, yielding ion pairing of -NR4(+) and -COO(-) on part of the capping monolayer. Analysis of the phase extraction allowed a quantitative determination of the percentage of ion pairing and structural changes in the capping monolayer on the nanoparticles. The results, along with morphological characterization, are discussed in terms of the interfacial structural changes and their implications on the rational design of surface-functionalized nanoparticles and fine tuning of the interfacial reactivity.

Determination of ion pairing on capping structures of gold nanoparticles by phase extraction.

As nanoparticles with different capping structures in solution phases have found widespread applications of wide interest, understanding how the capping structure change influences their presence in phases or solutions is important for gaining full control over both the intended nanoactivity and the unintended nanotoxicity. This report describes a simple and effective phase extraction method for analyzing the degree of ion pairing in the capping molecular structure of nanoparticles. Gold nanoparticles of a few nanometers diameter with a mixed monolayer capping structure consisting of both hydrophobic and hydrophilic and reactive groups were studied as a model system, and a quantitative model was derived based on chemical equilibria in a two-phase system, and used to assess the experimental data for phase extraction by cationic species. In contrast to the traditional perception of 100% ion pairing, only a small fraction (∼20%) of the negatively-charged groups was found to be responsible for the phase extraction. The viability of using this phase extraction method for analyzing the degree of ion-pairing in the capping molecular structure of different nanoparticles is also discussed, which has implications for the control of the nanoactivity and nanotoxicity of molecularly-capped or bio-conjugated nanoparticles.

Thin film assemblies of molecularly-linked metal nanoparticles and multifunctional properties.

The use of metal nanoparticles as building blocks toward thin film assembly creates intriguing opportunities for exploring multifunctional properties. Such an exploration requires the ability to engineer the size, shape, composition, and especially interparticle properties in nanoparticle assemblies for harnessing the collective properties of the nanoscale building blocks. This article highlights some of the important findings of our investigations of thin film assemblies of molecularly linked nanoparticles for exploiting their multifunctional and collective properties in molecular recognition and chemical sensing. The thermally activated processing approach presents a viable pathway for nanoengineering metal, alloy, and core-shell nanoparticles as building blocks. The molecular mediator-templating approach offers an effective strategy to thin film assemblies of the nanoscale building blocks that impart multifunctional properties. In such thin film assemblies, the interparticle interactions and structures dictate the correlation between the nanostructural parameters and the optical and electrical properties. By highlighting selected examples involving ligand-framework binding of ionic species at the film/liquid interface and electrical responses to molecular sorption at the film/gas interface, the multifunctional properties of the thin film assemblies are further discussed in terms of interparticle covalent, hydrogen bonding, ionic, or van der Waals interactions in a framework-type architecture for the creation of molecular recognition and chemical sensing sites that can be tuned chemically or electrochemically. Implications of these insights to expanding the exploration of nanoparticle thin film assemblies for a wide range of technological applications are also discussed.

Fabrication of magnetic core@shell Fe oxide@Au nanoparticles for interfacial bioactivity and bio-separation.

The immobilization of proteins on gold-coated magnetic nanoparticles and the subsequent recognition of the targeted proteins provide an effective means for the separation of proteins via application of a magnetic filed. A key challenge is the ability to fabricate such nanoparticles with the desired core-shell nanostructure. In this article, we report findings of the fabrication and characterization of gold-coated iron oxide (Fe2O3 and Fe3O4) core@shell nanoparticles (Fe oxide@Au) toward novel functional biomaterials. A hetero-interparticle coalescence strategy has been demonstrated for fabricating Fe oxide@Au nanoparticles that exhibit controllable sizes ranging from 5 to 100 nm and high monodispersity. Composition and surface analyses have proven that the resulting nanoparticles consist of the Fe2O3 core and the Au shell. The magnetically active Fe oxide core and thiolate-active Au shell were shown to be viable for exploiting the Au surface protein-binding reactivity for bioassay and the Fe oxide core magnetism for magnetic bioseparation. These findings are entirely new and could form the basis for fabricating magnetic nanoparticles as biomaterials with tunable size, magnetism, and surface binding properties.

Application of vacuum-assisted therapy in postoperative ascitic fluid leaks: an integral part of multimodality wound management in cirrhotic patients.

Surgery in patients with hepatic cirrhosis and ascites is associated with significant morbidity, including poor wound healing. Postoperative management of abdominal and perineal wounds in these patients poses a unique challenge owing to increased intra-abdominal pressure, risk for peritonitis, and ascitic fluid leakage. Vacuum-assisted closure (VAC) therapy reportedly improves angiogenesis and epithelialization, controls bacterial contamination, and removes excess tissue fluid. We present 4 cases of successful management of intractable postoperative ascitic fluid leaks utilizing VAC-based techniques. In one case, closure of a profusely draining perineal wound following an abdominoperineal resection was accomplished within 5 days of specialized VAC dressing application. In the other 3 cases, refractory drainage from midline laparotomy incision was successfully managed with the use of VAC therapy. In all 4 cases, the VAC-based system was effective in controlling drainage of ascites and subsequently sealing the wounds. Postoperative use of VAC in conjunction with optimization of medical therapy and judicious tapping of ascites provides a safe and effective method to control ascitic fluid leaks and promote definitive tissue sealing in patients with hepatic cirrhosis.

Array of molecularly mediated thin film assemblies of nanoparticles: correlation of vapor sensing with interparticle spatial properties.

The ability to tune interparticle spatial properties of nanoparticle assemblies is essential for the design of sensing materials toward desired sensitivity and selectivity. This paper reports findings of an investigation of molecularly mediated thin film assemblies of metal nanoparticles with controllable interparticle spatial properties as a sensing array. The interparticle spatial properties are controlled by a combination of alpha,omega-difunctional alkyl mediators (X-(CH(2))(n)-X) such as alkyl dithiols, dicarboxylate acids, and alkanethiol shells capped on nanoparticles. Alkanethiolate-capped gold and gold-silver alloy nanoparticles (2-3 nm) were studied as model building blocks toward the thin film assemblies, whereas the variation of alkyl chain length manipulates the interparticle spacing. The thin films assembled on an interdigitated microelectrode array platform are characterized for determining their responses to the sorption of volatile organic compounds (VOCs). The correlation between the response sensitivity and the interparticle spacing properties revealed not only a clear dependence of the sensitivity on alkyl chain length but also the occurrence of a dramatic change of the sensitivity in a region of chain length for the alkyl mediator comparable with that of the capping alkyl chains. This finding reflects a balance between the interparticle chain-chain cohesive interdigitation and the nanostructure-vapor interaction which determines the relative change of the electrical conductivity of the inked nanoparticle thin film in response to vapor sorption. The results, along with statistical analysis of the sensor array data in terms of sensitivity and selectivity, have provided important insights into the detailed delineation between the interparticle spacing and the nanostructured sensing properties.

Frequency of sentinel lymph node metastases in patients with favorable breast cancer histologic subtypes.

BACKGROUND: The need for axillary nodal staging in favorable histologic subtypes of breast cancer is controversial. METHODS: Patients with clinical stage T1-2, N0 breast cancer were enrolled in a prospective, multi-institutional study. All patients underwent sentinel lymph node (SLN) biopsy followed by completion level I/II axillary dissection. RESULTS: SLN were identified in 3,106 of 3,324 patients (93%). Axillary metastases were found in 35% and 40% of patients with infiltrating ductal carcinoma and infiltrating lobular carcinoma, respectively. Among tumor subtypes, positive nodes were found in 17% of patients with pure tubular carcinoma, 7% of patients with papillary cancer, 6% of patients with colloid (mucinous) carcinoma, 21% of patients with medullary carcinoma, and 8% of patients with DCIS with microinvasion. CONCLUSIONS: Patients with favorable breast cancer subtypes have a significant rate of axillary nodal metastasis. Axillary nodal staging remains important in such patients; SLN biopsy is an ideal method to obtain this staging information.