Biomedical subjects

M D Garrison

Publications and source records attributed to M D Garrison.

7 recordsLinked to original sources

PubMed2001

Plasma lithography--thin-film patterning of polymeric biomaterials by RF plasma polymerization I: Surface preparation and analysis.

Plasma lithography, combining plasma deposition with photolithography, is described as a versatile method to manufacture all-polymeric substrates with thin-film patterns for applications in biomedical engineering. Patterns of a hydrophobic fluorocarbon plasma polymer with feature sizes between 5 and 100 microm were deposited on a base substrate in a lift-off process: an intermediate tetraglyme plasma polymer layer provides non-fouling properties to the base substrate. Careful analysis of critical process parameters identified the narrow window of process conditions that led to the formation of functional surface patterns. High pattern fidelity, aspect ratios, and resolution of the patterns are demonstrated by atomic force microscopy. Electron spectroscopy for chemical analysis (ESCA) and secondary ion mass spectroscopy (SIMS) were used to characterize the surfaces, showing good retention of the original chemical structure of the pattern components throughout the process. SIMS imaging was used for specific chemical imaging of the components. Potential applications for the patterned polymer films, e.g., for studying cell behavior in vitro in dependence of shape and size of adhering cells, are discussed.

Biocompatible Materials↗

PubMed2000

Quantitative interrogation of micropatterned biomolecules by surface force microscopy.

Synthetic biomaterials are widely used in medical implants with success in improving and extending quality of life. However, these materials were not originally designed to interact with cells through specific signaling pathways. As a result, the interaction with the body is mediated through passive adsorption of a disorganized protein monolayer. Next generation biomaterials have been proposed to be active in modifying the biological response of the host through the incorporation of specific biorecognition moieties. An important tool in the development of these novel active biomaterials is the scanning force microscope (SFM). The SFM allows for interrogation of bioactive biomaterials in mapping or spectroscopic modes. In this work, micropatterned protein surfaces were prepared using biomolecules implicated in wound healing. The surfaces were imaged via SFM and the specific binding forces between surface associated biomolecules and antibody functionalized tips were quantified.

Antibodies↗

PubMed1999

Template-imprinted nanostructured surfaces for protein recognition.

Synthetic materials capable of selectively recognizing proteins are important in separations, biosensors and the development of biomedical materials. The technique of molecular imprinting creates specific recognition sites in polymers by using template molecules. Molecular recognition is attributed to binding sites that complement molecules in size, shape and chemical functionality. But attempts to imprint proteins have met with only limited success. Here we report a method for imprinting surfaces with protein-recognition sites. We use radio-frequency glow-discharge plasma deposition to form polymeric thin films around proteins coated with disaccharide molecules. The disaccharides become covalently attached to the polymer film, creating polysaccharide-like cavities that exhibit highly selective recognition for a variety of template proteins, including albumin, immunoglobulin G, lysozyme, ribonuclease and streptavidin. Direct imaging of template recognition is achieved by patterning a surface at the micrometre scale with imprinted regions.

Adsorption↗

PubMed1997

Scanning probe microscopy for the characterization of biomaterials and biological interactions.

The scanning probe microscopies provide a unique view of biological and biomedical systems at a nanoscale appropriate to appreciate molecular events. The advent of these methods has brought the ability to acquire quantitative information at the molecular level. Given the proliferation of microscopes and associated methods, the probability for important discoveries is high. If tempered with an appreciation for the potential for artifacts, the SPMs may revolutionize our view of biological systems and biomaterials interactions with those systems.

Animals↗

PubMed1997

A new method for straightening DNA molecules for optical restriction mapping.

We have developed an improved method of straightening DNA molecules for use in optical restriction mapping. The DNA was straightened on 3-aminopropyltriethoxysilane-coated glass slides using surface tension generated by a moving meniscus. In our method the meniscus motion was controlled mechanically, which provides advantages of speed and uniformity of the straightened molecules. Variation in the affinity of the silanized surfaces for DNA was compensated by precoating the slide with single-stranded non-target blocking DNA. A small amount of MgCl2 added to the DNA suspension increased the DNA-surface affinity and was necessary for efficient restriction enzyme digestion of the straightened surface-bound DNA. By adjusting the amounts of blocking DNA and MgCl2, we prepared slides that contained many straight parallel DNA molecules. Straightened lambda phage DNA (48 kb) bound to a slide surface was digested by EcoRI restriction endonuclease, and the resulting restriction fragments were imaged by fluorescence microscopy using a CCD camera. The observed fragment lengths showed excellent agreement with their predicted lengths.

Bacteriophage lambda↗

PubMed1995

Effect of PGML excipient mixture in a transdermal system on the in vitro transport of estradiol across skin.

PURPOSE: To measure the effect of a combination of excipients from a silicone based pressure sensitive adhesive (PSA) on drug transport across skin. METHODS: Partitioning of propylene glycol monolaurate (PG-ML) from silicone PSA and a solution formulation into the stratum corneum (SC) was measured using radiolabeled PG-ML. Transport of a model drug, estradiol, as well as PG-ML across skin were measured in vitro using heat separated epidermis from human cadaver skin. RESULTS: The PG-ML partitioning into SC showed a saturation and was independent of the formulation. The local dielectric of the lipid bilayers of the SC showed an increase as a result of PG-ML uptake, as determined by the decrease in fluorescence lifetime of a lipophilic probe incorporated into the SC. However, there was no alteration of lipid packing in SC. CONCLUSIONS: The PG-ML and estradiol transport showed a good correlation over 3 days, suggesting that the two species are co-transported across the epidermis.

Administration, Cutaneous↗

PubMed1994

Fluorescence spectroscopy of 9-anthroyloxy fatty acids in solvents.

A series of anthroyloxy fatty acid (AF) fluorescent probes, with the anthroyloxy group covalently linked at various positions along the alkyl chain, were studied in solvents exhibiting a wide range of polarity and hydrogen-bond donor (Hd) and acceptor (Ha) ability. These probes were sensitive to the solvent polarity as reflected by the Stokes' shift observed in steady state fluorescence. As determined by multi-linear regression analysis of the observed Stokes' shift and solvent parameters, such as orientation polarizability (delta f), Hd and Ha of the solvents, all the probes were sensitive to the Hd of solvents but were not affected by the Ha of solvents except the 2-AF. Due to the proximity of the polar headgroup to the fluorophore, it appears that some intramolecular hydrogen-bonding is present in 2-AF, an interaction that is sensitive to the pH of the solvent, but is less sensitive to the Hd and Ha of the solvents. Fluorescence lifetimes measured by the multi-frequency phase-modulation technique in mixtures of hexane and ethanol reflect a modified Stern-Volmer behavior suggesting the second solvent, ethanol, specifically interacts with the probe, in part through collisional quenching. Also, the lifetime data were sensitive to very low concentrations of the second solvent (0-0.1%, by vol.). The results from this study provide insight into the intrinsic differences between the different AF positions that must be taken into consideration while investigating the dynamics of lipid bilayer systems. Moreover, this study illustrates the utility and resolving power of lifetime based measurements needed for the interpretation of heterogeneous biophysical environments.

Anthracenes↗