An in situ microfluidic assembly approach is described that can both produce microsized building blocks and assemble them into complex multiparticle configurations in the same microfluidic device. The building blocks are microparticles of the biopolymer chitosan, which is intentionally selected because its chemistry allows for simultaneous intraparticle and interparticle linking. Monodisperse chitosan-bearing droplets are created by shearing off a chitosan solution at a microfluidic T-junction with a stream of hexadecane containing a nonionic detergent. These droplets are then interfacially crosslinked into stable microparticles by a downstream flow of glutaraldehyde (GA). The functional properties of these robust microparticles can be easily varied by introducing various payloads, such as magnetic nanoparticles and/or fluorescent dyes, into the chitosan solution. The on-chip connection of such individual particles into well-defined microchains is demonstrated using GA again as the chemical "glue" and microchannel confinement as the spatial template. Chain flexibility can be tuned by adjusting the crosslinking conditions: both rigid chains and semiflexible chains are created. Additionally, the arrangement of particles within a chain can also be controlled, for example, to generate chains with alternating fluorescent and nonfluorescent microparticles. Such microassembled chains could find applications as microfluidic mixers, delivery vehicles, microscale sensors, or miniature biomimetic robots.

The image illustrates an in‐situ dynamic microassembly on an integrated microfluidic platform that both produces microsized building blocks and also assembles them into complex multiparticle configurations. The building blocks used originate from microparticles produced microfluidically, with unprecedented control over particle size, geometry, and functional properties, while microfluidic channels serve as perfect spatial templates to accommodate building blocks into designed, highordered patterns. Advantages of this method include the simple chemistry for both interparticle curing and intraparticle linkage, and the facile control over subunit arrangement and microstructure flexibility. This microfluidic microassembly method conceptually envisions an integrated manufacturing platform where subunit generation and connection are accomplished on the same chip.

Methylene blue (MB) is a century-old medicine, a laboratory dye, and recently shown as a premier antioxidant that combats ROS-induced cellular aging in human skins. Given MB’s molecular structure and light absorption properties, we hypothesize that MB has the potential to be considered as a sunscreen active for UV radiation protection. In this study, we tested the effects of MB on UVB ray-induced DNA double-strand breaks in primary human keratinocytes. We found that MB treatment reduced DNA damages caused by UVB irradiation and subsequent cell death. Next, we compared MB with Oxybenzone, which is the most commonly used chemical active ingredient in sunscreens but recently proven to be hazardous to aquatic ecosystems, in particular to coral reefs. At the same concentrations, MB showed more effective UVB absorption ability than Oxybenzone and significantly outperformed Oxybenzone in the prevention of UVB-induced DNA damage and the clearance of UVA-induced cellular ROS. Furthermore, unlike Oxybenzone, MB-containing seawater did not affect the growth of the coral species Xenia umbellata. Altogether, our study suggests that MB has the potential to be a coral reef-friendly sunscreen active ingredient that can provide broad-spectrum protection against UVA and UVB.

This study presents a scientometric analysis of 253 articles published in Sadhana during the year 2005-2009. Five volumes of the journal are taken up to observe the distribution of contribution, authorship pattern, institution-wise distribution, geographical distribution of contribution, average length of paper, tables and illustrations used and citation pattern in each volume. Results indicate that highest number of papers have been written by two authors. The contributions received in this journal are more from India than from the other countries. Foreign documents show their more representation in references cited. Journals are referred more frequently than other documents.The average number of references per article is 23.72 and 200.602 per volume.

Methylene blue (MB) is a century-old medicine, a laboratory dye, and recently shown as a premier antioxidant that combats ROS-induced cellular aging in human skins. Given MB’s molecular structure and light absorption properties, we hypothesize that MB has the potential to be considered as a sunscreen active for UV radiation protection. In this study, we tested the effects of MB on UVB ray-induced DNA double strand breaks in primary human keratinocytes. We found that MB treatment reduced DNA damages caused by UVB irradiation and subsequent cell death. Next, we compared MB with Oxybenzone, which is the most commonly used chemical active ingredient in sunscreens but recently proven to be hazardous to aquatic ecosystems, in particular to coral reefs. At the same concentrations, MB showed similar broad-spectrum UV light absorption ability as Oxybenzone but significantly outperformed Oxybenzone in the prevention of UVB-induced DNA damage and the clearance of UVA-induced cellular ROS. Furthermore, unlike Oxybenzone, MB-containing seawater did not affect the growth of the coral species Xenia umbellata. Altogether, our study suggests that MB has the potential to be a coral reef-friendly sunscreen active ingredient that can provide broad-spectrum protection against UVA and UVB.

Capture of circulating tumor cells (CTCs) from blood shows promise as a relatively non-invasive screen for early stage metastasis, treatment efficacy, and disease progression. Capture rates exceeding 80% of CTCs from whole blood have been demonstrated in microfluidic chips, with good specificity and throughput at approximately 1 mL/h. The most common approach is to design a high surface-area microdevice and functionalize the surface with anti-EpCAM to capture epithelial tumor cells. As an alternative to this monolithic design, we have developed a CTC capture strategy based on functionalized beads for analyzing small numbers of CTCs from whole blood. Beads for the device were commercially available in a variety of sizes and surface chemistries or could be synthesized by multiple techniques. We utilized avidin-functionalized beads to enable capture using biotinylated antibodies (Ab) for surface-expressed proteins. Critically, batches of beads were assayed in bulk and then used for multiple experiments, avoiding characterization of each device. Beads packed well as columns in microdevices, ensuring multiple surface interactions as cells flow through. We simulated CTC-carrying blood by spiking human breast cancer adenocarcinoma (MFC7) cells (prestained with a membrane dye) into whole human blood between 1000 cells/mL and 105 cells/mL. Samples were delivered through the packed bed of beads using a syringe pump. We found that adding Ab to whole blood samples provided superior results to pre-coating the beads with the Ab. This approach was tested for multiple bead compositions and enabled (1) use of less Ab, and (2) higher capture rates, perhaps due to the rapid biotin:avidin binding. Significant cell capture was observed when as few as 300 cells were introduced into the device. At all cell densities, the majority of captured cells bound to the first few rows of beads, with decreasing capture frequency along the length of the column. Quantification of the absolute number of captured cells was a challenge in whole blood samples due to the large numbers of cells captured and optical distortion effects. We estimated capture by observing the initial capture rates of the same cells at the same densities in serum-spiked phosphate-buffered saline. This indicated that during the initial stages of flow, over 80% of the Ab-labeled cells were selectively captured. We conclude that the device can handle higher flowrates and still capture the majority of labeled cells. We are exploring the feasibility of this approach for capturing even lower CTC concentrations (1 cell/ml to 100 cells/mL range). Our bead/microfluidic approach simplifies CTC capture by enabling bulk surface functionalization for multiple experiments and allowing commercial sourcing of all functional elements. Further, there is flexibility in antibody selection, such that alternate Ab could rapidly be considered. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4070. doi:1538-7445.AM2012-4070