About

William Ducker is a professor in the Department of Chemical Engineering at Virginia Tech. He holds a Ph.D. from the Australian National University obtained in 1992 and a B.Sc. (Hons), First Class, from the same university in 1986. His research interests include lubrication in thin films, peptide, polymer and surfactant adsorption and self-assembly, colloidal stability, surface forces, enantioselectivity in adsorption, nanobubbles, and hydrogen storage. He is based in Goodwin Hall at Virginia Tech, located at 635 Prices Fork Road, Blacksburg, VA 24061. His contact email is wducker@vt.edu.

Research topics

• Materials science
• Computer Science
• Medicine
• Virology
• Composite material
• Chemistry
• Chemical physics
• Metallurgy
• Chemical engineering
• Biology
• Organic chemistry
• Engineering

Selected publications

• Utility of a commercially available transwell system for assessment of MSC-mediated mitigation of biofilms

  Journal of Microbiological Methods · 2025-11-15

  article
  PublisherDOI

• Effect of Salt on Synthetic Cationic Antimicrobial Polymer–Cell Interactions

  Biomacromolecules · 2025-05-19

  articleOpen accessSenior authorCorresponding

  Cationic antiseptics are deployed in a variety of settings, where salinity ranges from almost pure water to hypertonic salt. Here, we examine how dissolved NaCl affects the antimicrobial action of a model antimicrobial, polydiallyldimethylammonium chloride (PDADMAC) to the bacterium Escherichia coli (E. coli). Fluorescence microscopy is used to measure the time course of both the adsorption of PDADMAC to E. coli and the cell viability. NaCl decreases the density of adsorbed PDADMAC and diminishes its efficacy. At NaCl concentrations at or above 0.15 M, PDADMAC no longer kills bacteria but still prevents reproduction by halting the growth in cell length. Reproduction can be restarted if PDADMAC is removed. Fluorescence depolarization measurements show that PDADMAC rigidifies model membranes, but salt reduces the rigidity. We therefore attribute the halt in cell growth to reversible bridging by the polymer on the cell surface that prevents expansion of the cell membrane.

  PublisherDOI

• Novel in Vitro Co-Culture System Allows Assessment of Msc-Mediated Mitigation of Biofilms

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• Capillary Rise for Inclined Walls

  The Journal of Physical Chemistry C · 2025-04-21

  articleOpen accessSenior author
  PublisherDOI

• Pore Size and Distribution are Important in Evaporation from Thin Porous Coatings

  SSRN Electronic Journal · 2024-01-01

  preprintOpen accessSenior author
  PublisherDOI

• Effect of Contact Angle on the Pressure Needed for a Liquid to Permeate a Cylindrical Pore

  SSRN Electronic Journal · 2024-01-01

  preprintOpen accessSenior author
  PublisherDOI

• Data–driven modelling makes quantitative predictions regarding bacteria surface motility

  PLoS Computational Biology · 2024-05-14 · 1 citations

  articleOpen accessCorresponding

  In this work, we quantitatively compare computer simulations and existing cell tracking data of P. aeruginosa surface motility in order to analyse the underlying motility mechanism. We present a three dimensional twitching motility model, that simulates the extension, retraction and surface association of individual Type IV Pili (TFP), and is informed by recent experimental observations of TFP. Sensitivity analysis is implemented to minimise the number of model parameters, and quantitative estimates for the remaining parameters are inferred from tracking data by approximate Bayesian computation. We argue that the motility mechanism is highly sensitive to experimental conditions. We predict a TFP retraction speed for the tracking data we study that is in a good agreement with experimental results obtained under very similar conditions. Furthermore, we examine whether estimates for biologically important parameters, whose direct experimental determination is challenging, can be inferred directly from tracking data. One example is the width of the distribution of TFP on the bacteria body. We predict that the TFP are broadly distributed over the bacteria pole in both walking and crawling motility types. Moreover, we identified specific configurations of TFP that lead to transitions between walking and crawling states.

  PublisherOA PDFDOI

• Equine bone marrow-derived mesenchymal stromal cells reduce established S. aureus and E. coli biofilm matrix in vitro

  PLoS ONE · 2024-10-31 · 1 citations

  articleOpen access

  Biofilms reduce antibiotic efficacy and lead to complications and mortality in human and equine patients with orthopedic infections. Equine bone marrow-derived mesenchymal stromal cells (MSC) kill planktonic bacteria and prevent biofilm formation, but their ability to disrupt established orthopedic biofilms is unknown. Our objective was to evaluate the ability of MSC to reduce established S. aureus or E. coli biofilms in vitro. We hypothesized that MSC would reduce biofilm matrix and colony-forming units (CFU) compared to no treatment and that MSC combined with the antibiotic, amikacin sulfate, would reduce these components more than MSC or amikacin alone. MSC were isolated from 5 adult Thoroughbred horses in antibiotic-free medium. 24-hour S. aureus or E. coli biofilms were co-cultured in triplicate for 24 or 48 hours in a transwell plate system: untreated (negative) control, 30 μg/mL amikacin, 1 x 106 passage 3 MSC, and MSC with 30 μg/mL amikacin. Treated biofilms were photographed and biofilm area quantified digitally. Biomass was quantified via crystal violet staining, and CFU quantified following enzymatic digestion. Data were analyzed using mixed model ANOVA with Tukey post-hoc comparisons (p < 0.05). MSC significantly reduced S. aureus biofilms at both timepoints and E. coli biofilm area at 48 hours compared to untreated controls. MSC with amikacin significantly reduced S. aureus biofilms versus amikacin and E. coli biofilms versus MSC at 48 hours. MSC significantly reduced S. aureus biomass at both timepoints and reduced S. aureus CFU at 48 hours versus untreated controls. MSC with amikacin significantly reduced S. aureus biomass versus amikacin at 24 hours and S. aureus and E. coli CFU versus MSC at both timepoints. MSC primarily disrupted the biofilm matrix but performed differently on S. aureus versus E. coli. Evaluation of biofilm-MSC interactions, MSC dose, and treatment time are warranted prior to testing in vivo.

  PublisherDOI

• Time-Resolved Killing of Individual Bacterial Cells by a Polycationic Antimicrobial Polymer

  ACS Biomaterials Science & Engineering · 2024-03-29 · 6 citations

  articleOpen accessSenior authorCorresponding

  Polycationic polymers are widely studied antiseptics, and their efficacy is usually quantified by the solution concentration required to kill a fraction of a population of cells (e.g., by Minimum Bactericidal Concentration (MBC)). Here we describe how the response to a polycationic antimicrobial varies greatly among members of even a monoclonal population of bacteria bathed in a single common antimicrobial concentration. We use fluorescence microscopy to measure the adsorption of a labeled cationic polymer, polydiallyldimethylammmonium chloride (PDADMAC, Mw ≈ 4 × 105 g mol–1) and the time course of cell response via a cell permeability indicator for each member of an ensemble of either Escherichia coli, Staphylococcus aureus, or Pseudomonas aeruginosa cells. This is a departure from traditional methods of evaluating synthetic antimicrobials, which typically measure the overall response of a collection of cells at a particular time and therefore do not assess the diversity within a population. Cells typically die after they reach a threshold adsorption of PDADMAC, but not always. There is a substantial time lag of about 5–10 min between adsorption and death, and the time to die of an individual cell is well correlated with the rate of adsorption. The amount adsorbed and the time-to-die differ among species but follow a trend of more adsorption on more negatively charged species, as expected for a cationic polymer. The study of individual cells via time-lapse microscopy reveals additional details that are lost when measuring ensemble properties at a particular time.

  PublisherOA PDFDOI

• Effect of contact angle on the pressure needed for a liquid to permeate a cylindrical pore

  Colloids and Surfaces A Physicochemical and Engineering Aspects · 2024-03-11 · 3 citations

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  PublisherDOI

Recent grants

• Non-Newtonian Fluids in Squeeze Films

  NSF · $309k · 2008–2012

• MRI-R2: Development of a Correlation Force Spectrometer

  NSF · $661k · 2010–2013

• Adsorption in Confined Films

  NSF · $393k · 2019–2022

Frequent coauthors

• Wade K. J. Mosse

  Australian Regenerative Medicine Institute

  24 shared

• Christopher D. F. Honig

  23 shared

• John Y. Walz

  22 shared

• Jacob N. Israelachvili

  22 shared

• Sally L. Gras

  University of Melbourne

  19 shared

• Leo L. M. Poon

  University of Hong Kong

  18 shared

• Merran L. Koppens

  18 shared

• Thomas R. Gengenbach

  CSIRO Manufacturing

  16 shared