This study reports the synthesis and characterization of novel ruthenium (II) complexes with the polydentate dipeptide, L-carnosine (2-[(3-aminopropanoyl)amino]-3-(1H-imidazol-5-yl)propanoic acid). Mixed-ligand complexes with the general composition [MLp(Cl)q(H2O)r]·xH2O (M = Ru(II); L = L-carnosine; p = 3 − q; r = 0–1; and x = 1–3) were prepared by refluxing aqueous solutions of the ligand with equimolar amounts of ruthenium chloride (black-alpha form) at 60 °C for 36 h. Physical properties of the complexes were characterized by elemental analysis, DSC/TGA, and cyclic voltammetry. The molecular structures of the complexes were elucidated using UV-Vis, ATR-IR, and heteronuclear NMR spectroscopy, then confirmed by density function theory (DFT) calculations at the B3LYP/LANL2DZ level. Two-dimensional NMR experiments (1H COSY, 13C gHMBC, and 15N gHMBC) were also conducted for the assignment of chemical shifts and calculation of relative coordination-induced shifts (RCIS) by the complex formed. According to our results, the most probable coordination geometries of ruthenium in these compounds involve nitrogen (N1) from the imidazole ring and an oxygen atom from the carboxylic acid group of the ligand as donor atoms. Additional thermogravimetric and electrochemical data suggest that while the tetrahedral-monomer or octahedral-dimer are both possible structures of the formed complexes, the metal in either structure occurs in the (2+) oxidation state. Resulting RCIS values indicate that the amide-carbonyl, and the amino-terminus of the dipeptide are not involved in chelation and these observations correlate well with theoretical shift predictions by DFT.

No abstract

We demonstrated rapid prototyping of templates for replica molding using a conventional laser printer. A polymer, polydimethylsiloxane, was cast directly on the transparency templates to make the replicas. The templates and replicas were characterized by scanning electron microscopy, profilometry, and optical microscopy. Four patterns, including an Electronic Industries Association resolution test pattern, were printed on transparencies at 600 dots per inch on a HP LaserJet 4M printer (Hewlett-Packard, Palo Alto, CA). Optimal precision and clarity occurred between intensity settings of 50-100. Mean pattern height/depth ranged from 8-13 m, and width was as small as a few tenths of a millimeter. Mean surface roughness of the template patterns ranged from 1 to 4 m on the top surface and from 5 to 10 nm on the bare transparency surface. This method provides access to microfabricated patterns for the broader research community without the need for sophisticated micromachining facilities.The interest in miniaturized systems for biochemical analysis and biomedical research continues to grow rapidly. Devices commonly referred to as micro total analytical systems (TAS) have been reported for a diverse range of applications, such as the determination of monoclonal antibodies, 1 the determination of phosphate 2 and nitrite, 3 and for high-speed DNA sequencing. 4 The application of similar devices to cell culture and cell mechanics 5 is also expanding to include the geometric control of cell shape, 6 orientation, and gene expression, 7 as well as the adhesion of neurons 8 and growth cone guidance. 9 The devices themselves usually require photolithographic microfabrication techniques to produce them since conventional machining will not provide sufficiently small devices (colloquially referred to as chips). A review by Madou provides information relating to all aspects of microfabrication. 10 Chip-based devices manufactured from glass are perhaps the most widely used in part because of the versatility and chemical resistivity of glass, the relatively straightforward fabrication, and the ease of optical detection in glass devices. However, a major problem frequently encountered by researchers without specialized facilities is how to produce prototype devices rapidly and at a realistic cost. This paper describes a practical method for the fabrication of templates, stamps, or molds using a laser printer with resolution of 600 dots per inch (dpi) or greater and solvent-free transparency film as a substrate (Fig. 1). The overall time from a computer design to a micropatterned surface is 14-24 h, most of which is for curing the polymer. No access to spin coaters, ultraviolet radiation, or tools normally found in the semiconductor process is

Saquinavir (SQV), a candidate for buccal drug delivery, is limited by poor solubility. This study identified the effects of high-energy ball milling on the buccal permeability of SQV and compared it to the effects of chemical enhancers, i.e. ethylenediaminetetraacetic acid (EDTA), sodium lauryl sulfate (SLS), polyethylene glycol (PEG) and beta cyclodextrin (β-cyclodextrin). SQV was ball milled using a high energy planetary mill (1, 3, 15 and 30 h) and permeation studies across porcine buccal mucosa were performed using franz diffusion cells. Drug was quantified by UV spectrophotometry. Both unmilled and milled SQV samples were able to permeate the buccal mucosa. Milled samples of 15 h displayed the greatest flux of 10.40 ± 1.24 µg/cm(2 )h and an enhancement ratio of 2.61. All enhancers were able to increase the buccal permeability of unmilled SQV, with SLS achieving the greatest flux (6.99 ± 0.7 µg/cm(2)) and an enhancement ratio of 1.75. However, all the milled SQV samples displayed greater permeability than SLS, the best chemical enhancer for unmilled SQV. Enhanced permeability by ball milling was attributed to reduction in particle size, formation of solid dispersions and an increase in solubility of milled samples. Microscopical evaluation revealed no significant loss in mucosal cellular integrity treated with either unmilled or milled SQV. Histological studies suggest that SQV uses both the paracellular and transcellular route of transport across the mucosa, with drug treatment having no permanent affects. High-energy ball milling was superior to the chemical enhancers studied for enhancement of SQV buccal permeation.