Biomedical subjects

Ian Papautsky

Publications and source records attributed to Ian Papautsky.

5 recordsLinked to original sources

PubMed2006

Culture-based MEMS device to track Gordonia in activated sludge.

Previously, we reported on the use of microelectromechanical systems (MEMS) fabrication technologies to develop paraffin surfaces for miniaturization of culture-based detection and rapid quantification of Mycolata in environmental samples. In the current study, the novel culture-based biochip was calibrated with a broad range of pure cultures of Mycolata including Gordonia spp. isolated from activated sludge foam. The biochip successfully recovered Gordonia amarae spiked into a sample of mixed liquor collected from a municipal activated sludge system. Comparisons of these results with molecular biology-based assays including 16S rRNA-targeted fluorescence in situ hybridization (FISH) and antibody staining demonstrated that the biochip provides a more rapid and user-friendly platform for reliable identification and quantification of Mycolata in full-scale municipal activated sludge sewage treatment plants. The results of this work successfully demonstrate an alternative platform technology for inexpensive monitoring of environmental microorganisms using existing expertise by potential users in the area of bacterial cultivation.

Calibration↗

PubMed2006

Microtextured polydimethylsiloxane substrates for culturing mesenchymal stem cells.

Musculoskeletal tissue-engineering strategies have recently focused on the use of biomaterial scaffolds capable of guiding growth and organization of mesenchymal stem cells (MSCs), which are precursors for connective tissues. This chapter describes the methods for culturing MSCs on micropatterned polydimethylsiloxane (PDMS) substrates. MSCs are isolated from bone marrow biopsies and subcultivated before plating onto PDMS substrates. Micropatterned substrates are fabricated by casting PDMS on AZ P4620 photoresist molds. Prior to plating cells, substrates are cleaned, sterilized, and coated with fibronectin. Micropatterned growth surfaces are a useful research tool enabling the study of cell morphology and alignment in response to substrate geometry. Understanding MSC response to surface topography will assist in the design of improved scaffolds for connective-tissue repair.

Animals↗

PubMed2005

Miniaturized redox potential probe for in situ environmental monitoring.

The need for accurate, robust in situ microscale monitoring of oxidation-reduction potentials (ORP) is required for continuous soil pore water quality monitoring. We are developing a suite of self-contained microelectrodes that can be used in the environment, such as at Superfund sites, to monitor ORP in contaminated soils and sediments. This paper presents details on our development of microelectrode sensor arrays for ORP measurements. The electrochemical performance of these ORP electrodes was fully characterized by measuring redox potentials in standard solutions. It found that the newly developed integrated ORP microelectrodes produced a very stable voltage response (the corresponding rate of the integrated microelectrode potential change was in the range of 0.6-1.1 mV/min), even when the measurement was carried out outside of a Faraday cage where signals from most conventional microelectrodes are usually inhibited by external electrical nose. These new microelectrodes were easier to fabricate and were more robust than conventional microelectrodes. The tip size of the integrated ORP microelectrode was approximately 200 nm square, with a taper angle of approximately 20 degrees and a length of 57 microm. The integrated ORP microelectrode exhibited better signal stability and substantially shorter response times (from less than a few milliseconds to 30 s, depending on the standard solution used) than the commercial millielectrode (a few minutes). Compared with the slope of the commercial millelectrode, the slope of the integrated microelectrode (61.5 mV/pH) was closerto the ideal slope against quinhydrone calibration solutions. Therefore, it is to be expected that the newly developed ORP microelectrode may have wider applications in contaminated soils, biofilms, and sediments.

Electrochemistry↗

PubMed2004

Developing rapid detection of mycobacteria using microwaves.

In this paper, we describe the development of a culture-based biochip device for rapid detection of mycobacteria in environmental samples. Individual biochips rely upon the unique paraffinophilic nature of mycobacteria to rapidly and selectively adhere to the surface of the device. We used prototype biochips to experimentally demonstrate the concept of rapid and selective detection of mycobacteria by testing pure cultures and using epifluorescence microscopy to visualize microorganisms on the surface. As an alternative, rapid approach for identifying the biomass on the biochip surface, we used microwaves in the 10 to 26 GHz frequency range. The results of this study indicate that different microorganisms are responsible for specific shifts in resonance frequencies of a microwave cavity. By combing the semi-selective paraffin surface of the biochip with the microorganism-specific response to the microwaves, we have developed an improved analytical system with the potential to rapidly identify and enumerate mycobacteria in environmental samples in as little as 2 h.

Biosensing Techniques↗

PubMed2004

Micromachined arrays of cantilevered glass probes.

We describe the fabrication and characterization of cantilevered glass probe arrays. Individual probes have tapered shafts that are 175 microm square at the base and 200 nm square at the pyramidal tip. Each array contains as many as eight probes 10-20 mm long at 450-microm center-to-center spacing, fabricated from a single glass wafer by a combination of dicing and chemical etching. Optical signal losses of individual probes were measured to be of the order of 1 dB/cm. High-density data storage and page-oriented retrieval are the potential applications of the arrays.

Journal Article↗