Polycaprolactone Hybrid Scaffold Loaded With N,O-Carboxymethyl Chitosan/Aldehyde Hyaluronic Acid/Hydroxyapatite Hydrogel for Bone Regeneration.

Hydrogels have emerged as potential materials for bone grafting, thanks to their biocompatibility, biodegradation, and flexibility in filling irregular bone defects. In this study, we fabricated a novel NAH hydrogel system, composed of N,O-carboxymethyl chitosan (NOCC), aldehyde hyaluronic acid (AHA), and hydroxyapatite (HAp). To improve the mechanical strength of the fabricated hydrogel, a porous polycaprolactone (PCL) matrix was synthesized and used as a three-dimensional (3D) support template for NAH hydrogel loading, forming a novel PCL/NAH hybrid scaffold.

The Value of BRAF VE1 Immunoexpression in Pediatric Langerhans Cell Histiocytosis.

VE1 is a monoclonal antibody detecting mutant BRAF V600E protein by immunohistochemistry (IHC) with a high concordance rate with molecular analysis in many cancers. BRAF V600E mutation was assessed on 94 pediatric LCH patients using sequencing analysis and VE1 immunohistochemistry with stringent and lenient-scoring criteria. BRAF V600E mutation exon 15 was detected by sequencing in 47.

MicroPrep: chip-based dielectrophoretic purification of mitochondria.

We have developed a microfluidic system--microPrep--for subcellular fractionation of cell homogenates based on dielectrophoretic sorting. Separation of mitochondria isolated from a human lymphoblastoid cell line was monitored by fluorescence microscopy and further characterized by western blot analysis. Robust high throughput and continuous long-term operation for up to 60 h of the microPrep chip system with complex biological samples became feasible as a result of a comprehensive set of technical measures: (i) coating of the inner surfaces of the chip with BSA, (ii) application of mechanical actuators to induce periodic flow patterns, (iii) efficient cooling of the device to ensure integrity of organelle, (iv) a wide channel to provide for high fluidic throughput, and (v) integration of a serial arrangement of 10 dielectrophoretic deflector units to enable separation of samples with a high particle load without clogging.

Dielectrophoretic manipulation of DNA: separation and polarizability.

Although separation of polymers based on the combination of dielectrophoretic trapping and electrophoretic forces was proposed 15 years ago, experimental proof has not yet been reported. Here, we address this problem for long DNA fragments in a simple and easy-to-fabricate microfluidic device, in which the DNA is manipulated by electrophoresis and by electrodeless dielectrophoresis. By slowly increasing the strength of the dielectrophoretic traps in the course of the separation experiments, we are able to perform efficient and fast DNA separation according to length for two different DNA conformations: linear DNA (lambda (48.

Bioanalysis in structured microfluidic systems.

Microfluidic and lab-on-a-chip devices have attracted widespread interest in separation sciences and bioanalysis. Recent designs in microfluidic devices extend common separation concepts by exploiting new phenomena for molecular dynamics on a length scale of 10 mum and below, giving rise to novel manipulation tools and nonintuitive phenomena for microseparations. Here, we focus on three very recent developments for bioseparations based on tailored microfluidic systems: Single cell navigation, trapping and steering with subsequent on-chip lysis, protein separation and LIF detection (Section 3.

Brownian motion: absolute negative particle mobility.

Noise effects in technological applications, far from being a nuisance, can be exploited with advantage - for example, unavoidable thermal fluctuations have found application in the transport and sorting of colloidal particles and biomolecules. Here we use a microfluidic system to demonstrate a paradoxical migration mechanism in which particles always move in a direction opposite to the net acting force ('absolute negative mobility') as a result of an interplay between thermal noise, a periodic and symmetric microstructure, and a biased alternating-current electric field. This counterintuitive phenomenon could be used for bioanalytical purposes, for example in the separation and fractionation of colloids, biological molecules and cells.

Poly(oxyethylene) based surface coatings for poly(dimethylsiloxane) microchannels.

Control of surface properties in microfluidic systems is an indispensable prerequisite for successful bioanalytical applications. Poly(dimethylsiloxane) (PDMS) microfluidic devices are hampered from unwanted adsorption of biomolecules and lack of methods to control electroosmotic flow (EOF). In this paper, we propose different strategies to coat PDMS surfaces with poly(oxyethylene) (POE) molecules of varying chain lengths.

Two-state migration of DNA in a structured microchannel.

DNA migration in topologically structured microchannels with periodic cavities is investigated experimentally and with Brownian dynamics simulations of a simple bead-spring model. The results are in very good agreement with one another. In particular, the experimentally observed migration order of lambda - and T2-DNA molecules is reproduced by the simulations.

Mechanisms of DNA separation in entropic trap arrays: a Brownian dynamics simulation.

Using Brownian dynamics simulations, we study the migration of long charged chains in an electrophoretic microchannel device consisting of an array of microscopic entropic traps with alternating deep regions and narrow constrictions. Such a device has been designed and fabricated recently by Han and Craighead [Science 288 (2000) 1026] for the separation of DNA molecules. Our simulation reproduces the experimental observation that the mobility increases with the length of the DNA.