Design of a smartphone plastic optical fiber chemical sensor for hydrogen sulfide detection

We present a low-cost, handheld plastic optical fiber (POF) sensor for hydrogen sulfide (H2S) detection integrated onto a smartphone. The sensor uses smartphone flashlight as a source and camera as a pixel-based intensity detector. The POF is interconnected to the smartphone with a 3-D-printed connector on both source/detector sides. The sensing mechanism is embedded in the fiber link, making the system an all-fiber smartphone architecture. A mobile application handles data acquisition on the Android operative system. The sensor is functionalized for H2S detection through silver deposition on the POF outer surface. Experiments demonstrate the feasibility of the sensor system as the presence of H2S is successfully measured through an increase of optical losses through the POF link. This cost-effective, scalable, and compact sensor is promising for application in environmental sensing

POLY-L-ARGININE MODIFICATIONS ALTER THE ORGANIZATION AND SECRETION OF COLLAGEN IN SKH1-E MICE

Functionalized biomaterials interface with tissue upon implantation. There is a growing need to understand how materials properties influence this interaction so that efficient tissue engineering systems can be developed. In this study, we characterize collagen organization in response to functionalized glass beads implanted in SKH1-E mice. Poly-L-arginine (PLR) was modified with arginine derivatives to create a functionalized surface and was coated on glass beads. Tissue sections were removed 28 days post-implantation and were imaged using second harmonic generation (SHG) microscopy. These chemical modifications were able to alter the collagen dis tribution from highly aligned to disordered (17 ± 6 to 78 ± 1° full width at half-maximum (FWHM)) and the collagen III/I ratio (0.02 to 0.42). Principal component analysis (PCA) comparing the physical properties of the modifiers (e.g. hydrophobicity, molar volume, freely rotating bonds, polarizability) with the SHG analytically derived parameters (e.g. collagen III/I ratio, collagen orientation) was performed. Chemical properties of the PLR-like modifications including lipophilicity, along with the number of freely rotating bonds and the polar izability had significant effects on the collagen surrounding the implant, both in terms of collagen orientation as well as the production of collagen III. These findings demonstrate the possibility of tuning the foreign body response, in terms of collagen deposition and organization, to positively influence the acceptance of implanted biomaterials

Quantitative Characterization of Collagen in the Fibrotic Capsule Surrounding Implanted Polymeric Microparticles through Second Harmonic Generation Imaging

The collagenous capsule formed around an implant will ultimately determine the nature of its in vivo fate. To provide a better understanding of how surface modifications can alter the collagen orientation and composition in the fibrotic capsule, we used second harmonic generation (SHG) microscopy to evaluate collagen organization and structure generated in mice subcutaneously injected with chemically functionalized polystyrene particles. SHG is sensitive to the orientation of a molecule, making it a powerful tool for measuring the alignment of collagen fibers. Additionally, SHG arises from the second order susceptibility of the interrogated molecule in response to the electric field. Variation in these tensor components distinguishes different molecular sources of SHG, providing collagen type specificity. Here, we demonstrated the ability of SHG to differentiate collagen type I and type III quantitatively and used this method to examine fibrous capsules of implanted polystyrene particles. Data presented in this work shows a wide range of collagen fiber orientations and collagen compositions in response to surface functionalized polystyrene particles. Dimethylamino functionalized particles were able to form a thin collagenous matrix resembling healthy skin. These findings have the potential to improve the fundamental understanding of how material properties influence collagen organization and composition quantitatively.This article is published as Akilbekova, Dana, and Kaitlin M. Bratlie. "Quantitative characterization of collagen in the fibrotic capsule surrounding implanted polymeric microparticles through second harmonic generation imaging." PLOS ONE 10, no. 6 (2015): e0130386, DOI: 10.1371/journal.pone.0130386. Posted with permission.</p

A) Histograms of χzzzχzxx values obtained for gels with varying collagen type III concentration.

<p>The bars represent experimentally acquired data. The red line is the bimodal Gaussian fit to the data. B) Standard curve for collagen type III concentration. The known concentration of collagen concentration is plotted against the ratio of the area under the collagen type III peak ~0.8 to the total area under the Gaussian fit.</p

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