Group Members
Summer 2008

Chevelle Cason
Tony Haskamp
Whitney Schmidt
Zineb Syed
Stephen Wall
Hector Urcia
 
 

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ATR-FTIR Instrumentation

Dimension 3100 AFM

AFM image of Fe₂O₃ sol-gel film

RESEARCH INTERESTS    
Biofilm Adhesion  
The Bullen Research Group conducts multidisciplinary research that involves the use of attenuated total reflectance infrared spectroscopy (ATR-FTIR) in conjunction with other analytical methods to study biofilms, which have a profound impact on industrial, food processing, and medical settings.

Project 1: To date, a detailed understanding of biofilm formation is lacking.  Current models of the early stages of biofilm adhesion do not account for chemical reactions that may occur at the surface of a substrate.  Our research is focused on understanding the role of siderophores (organic ligands produced by most bacteria that have a high binding affinity for iron) in bacterial adhesion to metal oxide surfaces. 
Project 2: We are also evaluating protective (nonbiofouling) coatings for stainless steel medical implants.
Collaborators: Dr. Hazel Barton

Customizable Polymers (Dendrimers) for Drug Delivery to the Brain

The Bullen Research Group also has a collaborative project with Dr. Martines,  Dr. Russell, and Dr. Walters in investigating the use of custom dendrimers for drug delivery across the blood brain barrier (BBB).  This project utilizes atomic force microscopy and ATR-FTIR to investigate penetration of dendrimers into model BBBs.

Schematic of atomic force microscope (AFM).

Selected  Publications
H. A. Bullen. “Teaching Surface Characterization to Undergraduates.” Anal. Bioanal. Chem. 2007, 387, 1579-1581.

H. A. Bullen, M. J. Dorko, J. K. Oman, and S. J. Garrett "Valence and Core-Level Binding Energy Shifts in Orpiment (As₂S₃), Realgar (As₄S₄) and Pararealgar (As₄S₄) Arsenic Sulfide" Surf. Sci. 2003, 531, 319.

H. A. Bullen, S. J. Garrett "TiO₂ Nanoparticle Arrays Prepared Using a Nanosphere Lithography Technique" Nano Letters 2002, 2, 739.

H. A. Bullen, S. J. Garrett "CrO₂ by XPS: Comparison of CrO₂ Powder to CrO₂ films on TiO₂(110) Single Crystal Surfaces" Surf. Sci. Spectra 2002, 8, 225.

H. A. Bullen, S. J. Garrett “Epitaxial Growth of CrO₂ Thin Films on TiO₂(110) Surfaces” Chem. of Mater. 2002, 14, 243.

Selected Presentations (* indicates undergraduates)

W. L. Schmidt,* H. A. Bullen. “Catecholate siderophore complexation on metal oxide surfaces.” ACS National Meeting, Chicago, IL, March 2007. (Poster)

R. A Wilson*, H. A. Bullen. “Surface modification of stainless steel medical implants for biofouling prevention.” ACS National Meeting, Chicago, IL, March 2007. (Poster)

T. Fabre,* J. Hogan,* K. A. Walters, K. H. Martines, D. A. Tomalia, H. A. Bullen. “Design and characterization of drug delivery systems across the blood brain barrier.” ACS National Meeting, Chicago, IL, March 2007. (Poster)

J. Hogan,* T. Fabre,* K. A. Walters, K. H. Martines, D. A. Tomalia, H. A. Bullen. “ATR-FTIR analysis of the interaction of biotinylated dendrimers with blood brain barrier models.” ACS National Meeting, Chicago, IL, March 2007. (Poster)

S. Proctor,* H. A. Barton, H. A. Bullen. “Impact of pyoverdin siderophores extracted from Pseudomonas aeruginosa on bacterial adhesion to metal oxides.” ACS National Meeting, Chicago, IL, March 2007. (Poster)

C. D. Girten,* Jody R. Helton,* D. A. Tomalia, K. H. Martines, H. A. Bullen, K. A. Walters. “Surface modification of G4 and G5 PAMAM Dendrimers” ACS National Meeting, Chicago, IL, March 2007. (Poster)

H. A. Bullen, K. A. Walters. “Development of a nanomaterials one week intersession course at NKU.” ACS National Meeting, Chicago, IL, March 2007. (Talk)

H. A. Bullen. “Open access peer review port for communicating chemistry: Analytical Sciences Digital Library.” ACS National Meeting, Chicago, IL, March 2007. (Talk)

H. A. Bullen, R. A. Wilson, S. Proctor, W. Schmidt, P. J. Hogan, H. J. Stahl, M. Shields. “Probing biofilm formation: spectroscopic and scanning probe microscopy characterization of bacterial adhesion onto metal oxide surfaces.” Pittcon Conference, Chicago, IL, February 2007. (Poster)

A. Bennett* H. A. Bullen, and H. A. Barton. “Improved Methods to Relate Metabolic Activities to Biogeochemical Signatures in Carbonate Rock.” CUR Posters at Hill, Washington D. C., April 2006. (Poster)

A. Bennett,* H. A. Bullen, and H. A. Barton. “Improved Methods to Relate Metabolic Activities to Biogeochemical Signatures in Carbonate Rock”  KAS Meeting, Richmond, KY, Nov.  2005.

H. J. Gulley*, H. A. Bullen.  “Impact of Aqueous-Metal Oxide Interfaces on Biofilm Formation: ATR-FTIR as an In-Situ Approach to Probe Bacterial Adhesion” ACS National Meeting, San Diego, CA, March 2005.