About

Melgardt M. de Villiers is a Professor and Vice Dean, Associate Dean for Academic Affairs at the School of Pharmacy, University of Wisconsin–Madison. He holds degrees in pharmacy, pharmaceutics, and higher education from North-West University in Potchefstroom, South Africa. After faculty appointments at North-West University and the University of Louisiana at Monroe, and a sabbatical at the University of Iowa, he joined the Wisconsin faculty in 2005. He also serves as an extraordinary professor at the Centre of Excellence for Pharmaceutical Sciences at North-West University, South Africa. He is an associate editor for AAPS PharmSciTech and the Journal of Biomedical Nanotechnology. In 2005, he was recognized as the Outstanding Professor in the College of Health Sciences at the University of Louisiana at Monroe, and in 2012 he was elected a fellow of the American Association of Pharmaceutical Scientists (AAPS). Professor de Villiers' research focuses on the pharmaceutical sciences underlying drug delivery technologies, integrating pharmaceutics, engineering, and materials science principles to design, develop, and manufacture improved drug delivery systems. His work emphasizes the development of innovative nano- and microparticulate drug delivery systems aimed at treating and preventing communicable and chronic diseases. His research includes the application of layer-by-layer self-assembly, dendrimers, and calixarenes in drug delivery and drug solubilization. He has authored or co-authored over 150 peer-reviewed publications and has presented his research at more than 100 international meetings.

Research topics

• Medicine
• Materials science
• Pharmacology
• Biochemistry
• Chemistry
• Microbiology
• Chromatography
• Nanotechnology
• Biology
• Traditional medicine
• Dermatology
• Virology
• Mathematics
• Dentistry
• Organic chemistry

Selected publications

• Entropy-Driven Liquid–Liquid Phase Separation Transition to Polymeric Micelles

  The Journal of Physical Chemistry B · 2023-09-06 · 4 citations

  articleOpen access

  In recent years, liquid–liquid phase separation (LLPS) has been recognized to act as a precursor to self-assembly in amphiphilic systems. In this study, we propose the use of entropy-driven LLPS to obtain a tunable precursor for polymeric micelle formation. In this new approach, an oligomer is utilized as a nonselective solvent for the block copolymer, allowing for the tuning of entropy and subsequent LLPS. A comprehensive model was developed using mean-field lattice theory to predict the conditions under which LLPS and micellization occur. The degree of polymerization of the solvent was found to have a significant impact on the phase behavior of the system, outweighing enthalpic contributions such as the interaction between the blocks of the copolymer and the solvent. Our model predicts that using a solvent with a degree of polymerization equal to or greater than 5 for a copolymer such as PEG4kDa-b-PLA2.2kDa will result in LLPS prior to complete micellization, regardless of the values of interaction parameters. It also suggests that phase-separated liquid and polymeric micelles can co-exist in such a mixture. We confirmed our model predictions using dynamic light scattering and phase microscopy when PEG200 was used as the solvent. Micellization for PEG4kDa-b-PLA2.2kDa/PEG200/water mixture occurred at 10–12% w/w water content, consistent with the model predictions. Furthermore, the LLPS-to-micelle transition was shown to be reversible by changing the temperature or water content, indicating that the phase-separated liquid may be in thermodynamic equilibrium with polymeric micelles.

  PublisherOA PDFDOI

• In Vitro Skin Delivery of Griseofulvin by Layer-by-Layer Nanocoated Emulsions Stabilized by Whey Protein and Polysaccharides

  Pharmaceutics · 2022 · 9 citations

  Senior authorCorresponding
  • Chemistry
  • Chromatography
  • Pharmacology

  Griseofulvin is a poorly water-soluble drug administered orally to treat topical fungal infections of the skin and hair. However, oral administration leads to poor and unpredictable drug pharmacokinetics. Additionally, griseofulvin is unstable in the presence of light. A layer-by-layer (LbL) nanocoating approach was employed to curb these shortcomings by stabilizing emulsions, lyophilized emulsions, and reconstituted emulsions with a layer each of whey protein, and either hyaluronic acid, amylopectin, or alginic acid, which captured the drug. The coating materials are biological, environmentally benign, and plentiful. Photostability studies indicated that the LbL particles afforded 6 h of protection of the topical application. In vitro absorption studies showed that griseofulvin concentrated preferentially in the stratum corneum, with virtually no transdermal delivery. Therefore, LbL-nanocoated emulsions, lyophilized particles, and reconstituted lyophilized emulsions can produce a viable topical delivery system to treat superficial fungal infections.

  PublisherOA PDFDOI

• Oral Conventional Solid Dosage Forms: Powders and Granules, Tablets, Lozenges, and Capsules

  CRC Press eBooks · 2021 · 13 citations

  1st authorCorresponding
  • Materials science
  • Dentistry
  • Traditional medicine

  This chapter gives the student a sense of the importance of the basic knowledge and scientific principles required to understand the manufacturing, formulation, use, and biopharmaceutical aspects of conventional solid dosage forms. It focuses on conventional solid oral dosage forms and divides into three sections: powder and granules, tablets, and capsules. Lozenges are compressed tablets that do not contain a disintegrant. Oral powders generally can be supplied as finely divided powders or effervescent granules. The finely divided powders are suspended or dissolved in water or mixed with soft foods such as applesauce before administration. Dentifrices may be prepared in the form of a bulk powder, generally containing soap or detergent, mild abrasive, and anticariogenic agent. Douche powders are completely soluble and are dissolved in water prior to use as antiseptics or cleansing agents for a body cavity. Insufflations are finely divided powders introduced into body cavities such as the throat.

  PublisherDOI

• Layer-by-Layer Nanocoating of Antiviral Polysaccharides on Surfaces to Prevent Coronavirus Infections

  Molecules · 2020 · 49 citations

  Senior authorCorresponding
  • Chemistry
  • Virology
  • Nanotechnology

  In 2020, the world is being ravaged by the coronavirus, SARS-CoV-2, which causes a severe respiratory disease, Covid-19. Hundreds of thousands of people have succumbed to the disease. Efforts at curing the disease are aimed at finding a vaccine and/or developing antiviral drugs. Despite these efforts, the WHO warned that the virus might never be eradicated. Countries around the world have instated non-pharmaceutical interventions such as social distancing and wearing of masks in public to curb the spreading of the disease. Antiviral polysaccharides provide the ideal opportunity to combat the pathogen via pharmacotherapeutic applications. However, a layer-by-layer nanocoating approach is also envisioned to coat surfaces to which humans are exposed that could harbor pathogenic coronaviruses. By coating masks, clothing, and work surfaces in wet markets among others, these antiviral polysaccharides can ensure passive prevention of the spreading of the virus. It poses a so-called "eradicate-in-place" measure against the virus. Antiviral polysaccharides also provide a green chemistry pathway to virus eradication since these molecules are primarily of biological origin and can be modified by minimal synthetic approaches. They are biocompatible as well as biodegradable. This surface passivation approach could provide a powerful measure against the spreading of coronaviruses.

  PublisherOA PDFDOI

• Coarse-Grained Molecular Dynamics (CG-MD) Simulation of the Encapsulation of Dexamethasone in PSS/PDDA Layer-by-Layer Assembled Polyelectrolyte Nanocapsules

  AAPS PharmSciTech · 2020-10-22 · 6 citations

  articleSenior authorCorresponding
  PublisherDOI

• All-atomistic molecular dynamics (AA-MD) studies and pharmacokinetic performance of PAMAM-dendrimer-furosemide delivery systems

  International Journal of Pharmaceutics · 2018-06-13 · 13 citations

  articleSenior author
  PublisherDOI

• Dissipative Particle Dynamics Investigation of the Transport of Salicylic Acid through a Simulated In Vitro Skin Permeation Model

  Pharmaceuticals · 2018-12-05 · 15 citations

  articleOpen accessSenior author

  Permeation models are often used to determine diffusion properties of a drug through a membrane as it is released from a delivery system. In order to circumvent problematic in vivo studies, diffusion studies can be performed in vitro, using (semi-)synthetic membranes. In this study salicylic acid permeation was studied, employing a nitrocellulose membrane. Both saturated and unsaturated salicylic acid solutions were studied. Additionally, the transport of salicylic acid through the nitrocellulose membrane was simulated by computational modelling. Experimental observations could be explained by the transport mechanism that was revealed by dissipative particle dynamics (DPD) simulations. The DPD model was developed with the aid of atomistic scale molecular dynamics (AA-MD). The choice of a suitable model membrane can therefore, be predicted by AA-MD and DPD simulations. Additionally, the difference in the magnitude of release from saturated and unsaturated salicylic acid and solutions could also be observed with DPD. Moreover, computational studies can reveal hidden variables such as membrane-permeant interaction that cannot be measured experimentally. A recommendation is made for the development of future model permeation membranes is to incorporate computational modelling to aid the choice of model.

  PublisherOA PDFDOI

• Poly(amidoamine) Dendrimers as a Pharmaceutical Excipient. Are We There yet?

  Journal of Pharmaceutical Sciences · 2017-10-16 · 47 citations

  reviewOpen accessSenior author
  PublisherOA PDFDOI

• Application of halloysite clay nanotubes as a pharmaceutical excipient

  International Journal of Pharmaceutics · 2017-02-22 · 113 citations

  articleCorresponding
  PublisherDOI

• Paclitaxel Encapsulated in Halloysite Clay Nanotubes for Intestinal and Intracellular Delivery

  Journal of Pharmaceutical Sciences · 2017-06-07 · 109 citations

  article
  PublisherDOI

Frequent coauthors

• Wilna Liebenberg

  North-West University

  66 shared

• Mino R. Caira

  University of Cape Town

  30 shared

• Daniel P. Otto

  24 shared

• Mingna Song

  University of Louisiana at Monroe

  21 shared

• A. P. Lötter

  North-West University

  19 shared

• J. G. van der Watt

  15 shared

• William M. Kolling

  Southern Illinois University Edwardsville

  12 shared

• N. Stieger

  North-West University

  12 shared

Labs

• Melgardt de Villiers LabPI

  Developing novel nanometer and micrometer sized drug delivery systems. Application of layer-by-layer selfassembly, dendrimers and calixarenes in drug delivery and drug solubilization.

Education

• Other, Pharmacy

  North-West University

  1986

• M.S., Pharmacy

  North-West University

  1988

• Ph.D., Pharmaceutics

  North-West University

  1993

• Other, Higher Education

  North-West University

  1996

Awards & honors

• Outstanding Professor in the College of Health Sciences at t…
• Fellow of the American Association of Pharmaceutical Scienti…