Dr Khay Fong

Dr Khay Fong

Lecturer

School of Environmental and Life Sciences

Career Summary

Biography

The research of Dr Khay Fong centres upon the self-assembly of amphiphilic molecules into nanostructures and nanoparticles. The overarching aim of her research is to develop a platform nanotechnology that can be used in the creation of better medicines and diagnostic tools.
Drug delivery systems have been proposed as a “magic bullet” that health professionals might one day use to target diseases without harming healthy tissues. The aim of these systems is to localise drug delivery to diseased tissue at a specific time, protecting both the drug from being degraded in the body, and the body from systemic side effects from the drug. 

On-demand drug delivery
Dr Fong’s research adds an extra element of control where she has created nanomaterials that can be selectively turned on – by heat, laser light, a change in pH and digestion – on demand. Having control over when the drug is released will provide health care professionals ultimate control over treatment plans of patients.

Understanding fundamental interactions

Another major focus of Dr Fong’s research is the effect of the physiological environment on the properties on the drug delivery material itself. Your body contains thousands of biomolecules that can change the intended fate of nanoparticles when dosed. Understanding both the effect of native biomolecules on the drug delivery system as well as the effect of drug delivery system on physiological systems is essential for their realisation as on-demand treatments.

At UoN

Dr Fong is a Lecturer in Chemistry in the Faculty of Science in the School of Environmental and Life Sciences at the University of Newcastle. Her teaching focuses on analytical, physical and colloidal chemistry. Her research projects utilise synchrotron science, light scattering and synthesis of nanoparticles as well as novel amphiphiles.

Dr Fong is an active member of the Australasian Colloid and Interface Science Society.

Dr Fong stands for equity and diversity and has taken the UON Gender Equality Leadership Pledge.

Before UoN

Dr Fong completed her PhD at the Monash Institute of Pharmaceutical Sciences (2013). She subsequently was awarded a highly competitive Victorian Postdoctoral Research Fellowship which took her to ETH Zurich, Switzerland (2014-15) and back to Monash (2016). She was the first recipient of the National Center of Competence in Research in Bio-Inspired Materials Postdoctoral Research Fellowship for Women at the Adolphe Merkle Institute, Université de Fribourg, Switzerland (2017-18).


Qualifications

  • Doctor of Philosophy, Monash University
  • Graduate Certificate in Commercialising Research, Monash University

Keywords

  • colloid
  • drug delivery
  • light scattering
  • lipid
  • nanoparticle
  • nanostructure
  • physical chemistry
  • self assembly

Languages

  • English (Mother)

Fields of Research

Code Description Percentage
030304 Physical Chemistry of Materials 40
030302 Nanochemistry and Supramolecular Chemistry 30
100708 Nanomaterials 30

Professional Experience

UON Appointment

Title Organisation / Department
Lecturer University of Newcastle
School of Environmental and Life Sciences
Australia

Academic appointment

Dates Title Organisation / Department
1/06/2017 - 30/11/2018 Postdoctoral Research Fellow

This 18 month research project investigated two main projects:

1. the biological fate of nanostructured lipidic nanoparticles when exposed to complex media.  
2: the positioning of phosphate surfactants in a lipid bilayer depending on headgroup size and pH.

Adolphe Merkle Institute
University of Fribourg
Switzerland
27/01/2014 - 26/01/2017 Postdoctoral Research Fellow

This three year fellowship developed smart, enzyme responsive nanomaterials for disease detection and treatment. The project utilised the world-class skills, experience and facilities at ETH Zurich for 2 years and at Monash University (Pharmacy) for 1 year. 

ETH Zurich (Swiss Federal Institute of Technology Zurich)
Institute of Food, Nutrition and Health
Switzerland

Awards

Research Award

Year Award
2016 Faculty Early Career Researcher Award
Monash University
Edit

Publications

For publications that are currently unpublished or in-press, details are shown in italics.


Chapter (2 outputs)

Year Citation Altmetrics Link
2019 Fong WK, Moore TL, Balog S, Vanhecke D, Rodriguez-Lorenzo L, Rothen-Rutishauser B, et al., 'Nanoparticle behaviour in complex media: Methods for characterizing physicochemical properties, evaluating protein corona formation, and implications for biological studies', NanoScience and Technology 101-150 (2019)

© 2019, Springer Nature Switzerland AG. The transformation of nanoparticles (NPs) in physiological milieu is a dynamic phenomenon that is the subject of intense investigation. Whe... [more]

© 2019, Springer Nature Switzerland AG. The transformation of nanoparticles (NPs) in physiological milieu is a dynamic phenomenon that is the subject of intense investigation. When introduced into the body, NPs can undergo a variety of changes, such as, protein adsorption, dissolution, agglomeration/aggregation, structural deformities and redox reactions. It is these changes that subsequently determine the uptake, bioavailability, translocation and fate of NPs, which ultimately determine their therapeutic efficiency, diagnostic efficacy or toxicity. This chapter will consider the colloidal interactions at the interface of NPs with the contents of biological milieu, the practical and theoretical considerations required to modify analytical and imaging techniques to detect and, if possible, quantify NPs in this complex environment, and the requirement for a highly interdisciplinary approach to understand the behaviour at the bio-nano interface.

DOI 10.1007/978-3-030-12461-8_5
2012 Boyd BJ, Fong WK, 'Stimuli-Responsive Lipid-Based Self-Assembled Systems', Self-Assembled Supramolecular Architectures: Lyotropic Liquid Crystals 257-288 (2012)

Lipid based self assembled matrices have been proposed as novel drug delivery systems, as the phases formed by these materials have been shown to reliably encapsulate and control ... [more]

Lipid based self assembled matrices have been proposed as novel drug delivery systems, as the phases formed by these materials have been shown to reliably encapsulate and control the release of actives. The unique nanostructures formed by many lipids are dictated by the specifi c local packing of the amphiphiles in the matrix. Lipid packing is determined by molecular geometry of the lipids, which can be reversibly or irreversibly modifi ed by changes in environmental factors such as temperature and pH. In recent times, much research has tapped into the rich vein of liquid crystalline nanostructures and their manipulations for " on-demand " drug release. This chapter details the use of self assembled systems in drug delivery with a particular focus on how they have been rendered stimuli responsive and their potential uses in pharmaceutical therapies. © 2012 John Wiley and Sons, Inc.

DOI 10.1002/9781118336632.ch9
Citations Scopus - 7

Journal article (21 outputs)

Year Citation Altmetrics Link
2018 Ebersold MM, Petrovic M, Fong W-K, Bonvin D, Hofmann H, Milosevic I, 'Hexosomes with Undecylenic Acid Efficient against Candida albicans', NANOMATERIALS, 8 (2018)
DOI 10.3390/nano8020091
Citations Scopus - 1Web of Science - 2
2018 Jia S, Fong W-K, Graham B, Boyd BJ, 'Photoswitchable Molecules in Long-Wavelength Light-Responsive Drug Delivery: From Molecular Design to Applications', CHEMISTRY OF MATERIALS, 30 2873-2887 (2018)
DOI 10.1021/acs.chemmater.8b00357
Citations Scopus - 16Web of Science - 13
2017 Jia S, Du JD, Hawley A, Fong WK, Graham B, Boyd BJ, 'Investigation of Donor-Acceptor Stenhouse Adducts as New Visible Wavelength-Responsive Switching Elements for Lipid-Based Liquid Crystalline Systems', Langmuir, 33 2215-2221 (2017)

© 2017 American Chemical Society. The ability of donor-acceptor Stenhouse adducts (DASAs) to function as a green light responsive switch for lipid-based liquid crystalline drug de... [more]

© 2017 American Chemical Society. The ability of donor-acceptor Stenhouse adducts (DASAs) to function as a green light responsive switch for lipid-based liquid crystalline drug delivery systems was investigated. The host matrix comprising phytantriol cubic phase was selected due to its high sensitivity toward changes in lipid packing. Small-angle X-ray scattering demonstrated that the matrix undergoes rapid and fully reversible order-order phase transitions upon irradiation with 532 nm light, converting between the bicontinuous cubic phase and reversed hexagonal phases. This approach shows promise for use as an actuator for the development of visible wavelength light-activated, "on-demand" drug delivery systems.

DOI 10.1021/acs.langmuir.6b03726
Citations Scopus - 16Web of Science - 16
2017 Nyström G, Fong WK, Mezzenga R, 'Ice-Templated and Cross-Linked Amyloid Fibril Aerogel Scaffolds for Cell Growth', Biomacromolecules, 18 2858-2865 (2017)

© 2017 American Chemical Society. Amyloid fibrils prepared from ß-lactoglobulin were used to form freeze-dried and cross-linked aerogels. By varying the fibril concentration and f... [more]

© 2017 American Chemical Society. Amyloid fibrils prepared from ß-lactoglobulin were used to form freeze-dried and cross-linked aerogels. By varying the fibril concentration and freezing gradient, it was possible to control the pore structure and elastic modulus of the aerogels within one order of magnitude from ~20 to ~200 kPa. Using butane tetracarboxylic acid as cross-linker, these aerogels maintained their monolithic shape under aqueous conditions, displaying elastic behavior and a modulus in the range of ~4-40 kPa. When explored as scaffolds for cell growth, the amyloid fibril aerogels demonstrated biocompatibility and led to the successful penetration and permeation of two epithelial cell lines (Caco-2 and HT29) throughout the scaffold. These soft, elastic, and water-stable biomaterials expand the scope of amyloid fibril aerogels, making them suitable for wet-state applications such as heterogeneous catalysis, purification membranes, and 3D matrices for cell growth.

DOI 10.1021/acs.biomac.7b00792
Citations Scopus - 9Web of Science - 8
2017 Fong WK, Sánchez-Ferrer A, Ortelli FG, Sun W, Boyd BJ, Mezzenga R, 'Dynamic formation of nanostructured particles from vesicles via invertase hydrolysis for on-demand delivery', RSC Advances, 7 4368-4377 (2017)

© The Royal Society of Chemistry. The unique multicompartmental nanostructure of lipid-based mesophases can be triggered, on-demand, in order to control the release of encapsulate... [more]

© The Royal Society of Chemistry. The unique multicompartmental nanostructure of lipid-based mesophases can be triggered, on-demand, in order to control the release of encapsulated drugs. In this study, these nanostructured matrices have been designed to respond to a specific enzyme, invertase, an enzyme which catalyses the hydrolysis of sucrose. The effect of two sugar esters upon the phase behaviour of two different lipids which form cubic phases, phytantriol and monolinolein, was investigated. Factors affecting the hydrolysis of the sucrose headgroup are discussed in terms of the molecular structure of the sugar surfactant and also its ability to incorporate into the lipid bilayer. By hydrolysing the incorporated sugar esters, a dynamic change in mesophase nanostructure from vesicles to a cubic phase was observed. This phase change resulted in the triggered release of an encapsulated model drug, fluorescein. This investigation demonstrates, for the first time, that changes on a molecular level by subtly controlling the hydrophilic and hydrophobic features of an amphiphilic additive at the interface by enzymatic hydrolysis can result in a global change in the system and so paves the way towards the design and development of lipid-based matrices which are responsive to specific enzymes for the controlled delivery of pharmaceutically active molecules or functional foods.

DOI 10.1039/c6ra26688f
Citations Scopus - 2Web of Science - 2
2016 Fong WK, Negrini R, Vallooran JJ, Mezzenga R, Boyd BJ, 'Responsive self-assembled nanostructured lipid systems for drug delivery and diagnostics', Journal of Colloid and Interface Science, 484 320-339 (2016)

© 2016 Elsevier Inc. While stimuli-responsive polymers have received a huge amount of attention in the literature, responsive lipid-based mesophase systems offer unique opportunit... [more]

© 2016 Elsevier Inc. While stimuli-responsive polymers have received a huge amount of attention in the literature, responsive lipid-based mesophase systems offer unique opportunities in biomedical applications such as drug delivery and biosensing. The different mesophase equilibrium structures enables dynamic switching between nanostructures to facilitate drug release or as a transducer for recognition events. In drug delivery, this behavior offers researchers the means to deliver a therapeutic payload at a specific rate and time i.e. ¿on-demand¿. This review summarizes the distinctive features of these multifaceted materials and aggregates the current state of the art research from our groups and others into the use of these materials as bulk gels and nanostructured dispersions for drug delivery, biosensing and diagnostics.

DOI 10.1016/j.jcis.2016.08.077
Citations Scopus - 40Web of Science - 40
2016 Fong WK, Hanley TL, Thierry B, Hawley A, Boyd BJ, Landersdorfer CB, 'External manipulation of nanostructure in photoresponsive lipid depot matrix to control and predict drug release in vivo', Journal of Controlled Release, 228 67-73 (2016)

© 2016 Elsevier B.V. All rights reserved. On-demand drug delivery systems are highly promising to control the time-course of drug release and ultimately optimize drug concentratio... [more]

© 2016 Elsevier B.V. All rights reserved. On-demand drug delivery systems are highly promising to control the time-course of drug release and ultimately optimize drug concentration time profiles in patients. Lipid based lyotropic liquid crystalline mesophases have demonstrated exceptional responsiveness to external stimuli such as heat, pH and light. Our objective was to quantitatively characterize the time-course of light activated drug release from near infrared (NIR) activated photothermal systems using ex vivo and in vivo studies. Photoresponsive hybrid gold nanorod-liquid crystalline matrices were prepared and loaded into custom-made implants which were inserted into subcutaneous tissues in rats. Time resolved SAXS studies showed the abdomen to be the best site of implantation to achieve in vivo activation of the subcutaneous dose from by the NIR laser. External control of drug release was achieved via NIR laser light and plasma concentrations of the model drug were determined over time. Laser activation achieved a phase change of the photoresponsive formulations and thereby a considerable change in the rate of drug release. Population pharmacokinetic modeling of all results simultaneously revealed a two stage release process unique to these liquid crystalline matrices. The developed structural model was able to successfully describe also the results of our previous study in 2009 where a change in temperature was utilized to trigger subcutaneous drug release. Thus, modeling of the data proved to be a valuable analytical tool which provided a quantitative understanding of the time-course of drug release in vivo and will be essential in the development of these matrices as on-demand release systems.

DOI 10.1016/j.jconrel.2016.02.042
Citations Scopus - 15Web of Science - 15
2016 Du JD, Fong WK, Caliph S, Boyd BJ, 'Lipid-based drug delivery systems in the treatment of wet age-related macular degeneration', Drug Delivery and Translational Research, 6 781-792 (2016)

© 2016, Controlled Release Society. Recent advances in drug delivery technology have amplified potential opportunities to treat the debilitating diseases that affect the posterior... [more]

© 2016, Controlled Release Society. Recent advances in drug delivery technology have amplified potential opportunities to treat the debilitating diseases that affect the posterior segment of the eye in a less invasive and more efficient manner. Current methods for effective drug delivery to the back of the eye are hindered by many barriers and limitations. As a consequence, considerable efforts have been directed towards developing new materials to selectively deliver drug directly to the target site. This review focuses on lipid-based delivery systems which show promise in improving treatment for the most common disease of the posterior segment of the eye in the developed world, age-related macular degeneration, with an emphasis upon on-demand delivery systems as they have greater potential to overcome the current limitations.

DOI 10.1007/s13346-016-0299-6
Citations Scopus - 4Web of Science - 4
2016 Sun W, Vallooran JJ, Fong WK, Mezzenga R, 'Lyotropic Liquid Crystalline Cubic Phases as Versatile Host Matrices for Membrane-Bound Enzymes', Journal of Physical Chemistry Letters, 7 1507-1512 (2016)

© 2016 American Chemical Society. Lyotropic liquid crystalline cubic mesophases can function as host matrices for enzymes because of their biomimetic structural characteristics, o... [more]

© 2016 American Chemical Society. Lyotropic liquid crystalline cubic mesophases can function as host matrices for enzymes because of their biomimetic structural characteristics, optical transparency, and capability to coexist with water. This study demonstrates that the in meso immobilized membrane-bound enzyme d-fructose dehydrogenase (FDH) preserves its full activity, follows ideal Michaelis-Menten kinetics, and shows improved stability compared to its behavior in solution. Even after 5 days, the immobilized FDH retained its full activity in meso, whereas a model hydrophilic enzyme, horseradish peroxidase, maintained only 21% of its original activity. We reason that the lipidic bilayers in the three-dimensional structures of cubic mesophases provide an ideal environment for the reconstitution of a membrane-bound enzyme. The preserved activity, long-term stability, and reusability demonstrate that these hybrid nanomaterials are ideal matrices for biosensing and biocatalytic fuel cell applications.

DOI 10.1021/acs.jpclett.6b00416
Citations Scopus - 14Web of Science - 15
2015 Martiel I, Handschin S, Fong WK, Sagalowicz L, Mezzenga R, 'Oil transfer converts phosphatidylcholine vesicles into nonlamellar lyotropic liquid crystalline particles', Langmuir, 31 96-104 (2015)

© 2014 American Chemical Society. There is a need for the development of low-energy dispersion methods tailored to the formation of phospholipid-based nonlamellar lyotropic liquid... [more]

© 2014 American Chemical Society. There is a need for the development of low-energy dispersion methods tailored to the formation of phospholipid-based nonlamellar lyotropic liquid crystalline (LLC) particles for delivery system applications. Here, facile formation of nonlamellar LLC particles was obtained by simple mixing of a phosphatidylcholine (PC) liposome solution and an oil-in-water emulsion, with limonene or isooctane as an oil. The internal structure of the particles was controlled by the PC-to-oil ratio, consistently with the sequence observed in bulk phase. For the first time, reverse micellar cubosomes with Fm3¯m inner structure were produced. The size, morphology, and inner structure of the particles were characterized by small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and freeze-fracture cryo scanning electron microscopy (cryo-SEM). These findings pave the way to new strategies in low-energy formulation of LLC delivery systems.

DOI 10.1021/la504115a
Citations Scopus - 10Web of Science - 10
2015 Negrini R, Fong WK, Boyd BJ, Mezzenga R, 'PH-responsive lyotropic liquid crystals and their potential therapeutic role in cancer treatment', Chemical Communications, 51 6671-6674 (2015)

© The Royal Society of Chemistry 2015. A weak amphiphilic base, pyridinylmethyl linoleate, is blended with monolinolein, yielding mesophases with a pH-induced hexagonal-to-cubic t... [more]

© The Royal Society of Chemistry 2015. A weak amphiphilic base, pyridinylmethyl linoleate, is blended with monolinolein, yielding mesophases with a pH-induced hexagonal-to-cubic transition at pH = 5.5. We show the potential therapeutic role of this mesophase in treating cancerous tissues exploiting their more acidic pH compared to healthy tissues. In vitro release studies with doxorubicin on HT29 human colon cancer cells show a 10-fold faster release and 3-fold increased efficiency for killing cancer cells at pH 5.5 versus pH 7.4, demonstrating the potential of this strategy in cancer treatment. This journal is

DOI 10.1039/c4cc10274f
Citations Scopus - 38Web of Science - 37
2015 Du JD, Fong WK, Salentinig S, Caliph SM, Hawley A, Boyd BJ, 'Phospholipid-based self-assembled mesophase systems for light-activated drug delivery', Physical Chemistry Chemical Physics, 17 14021-14027 (2015)

© the Owner Societies 2015. The manipulation of the structure of phospholipid-based mesophases to induce a slow to fast drug release profile has potential for use in therapeutic s... [more]

© the Owner Societies 2015. The manipulation of the structure of phospholipid-based mesophases to induce a slow to fast drug release profile has potential for use in therapeutic situations where continuous absorption of drug is not desirable and reduce the frequency of injection for short acting or rapidly cleared drugs in treatments for diseases such as macular degeneration. This study had two aims; firstly to confirm the phase behaviour of 20 mol% cholesterol in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), which was previously reported to transition from lamellar (slow release) to bicontinuous cubic (fast release) phase with increasing temperature. Contrary to the literature, no bicontinuous cubic phase was observed but a transition to the inverse hexagonal phase occurred at all POPE:cholesterol ratios investigated. The second aim was to render these mesophases responsive to near-infrared laser (NIR) irradiation by incorporation of gold nanorods (GNR) incorporated into the POPE system to induce photothermal heating. The inclusion of 3 nM GNR in POPE systems induced reversible disruption of lipid packing equivalent to increasing the temperature to 55 °C when irradiated for 30 s. This study confirmed that although the previously published phase behavior was not correct, GNR and NIR can be used to manipulate the self-assembled mesophases in phospholipid-based systems and highlights the potential for a phospholipid-based light-activated drug delivery system.

DOI 10.1039/c5cp01229e
Citations Scopus - 10Web of Science - 10
2014 Fong WK, Salentinig S, Prestidge CA, Mezzenga R, Hawley A, Boyd BJ, 'Generation of geometrically ordered lipid-based liquid-crystalline nanoparticles using biologically relevant enzymatic processing', Langmuir, 30 5373-5377 (2014)

High-symmetry lipid nanoparticles with internal bicontinuous cubic phase structure (cubosomes) are prepared from a simple emulsion containing a mixture of a nondigestible lipid (p... [more]

High-symmetry lipid nanoparticles with internal bicontinuous cubic phase structure (cubosomes) are prepared from a simple emulsion containing a mixture of a nondigestible lipid (phytantriol) and a digestible short-chained triglyceride using enzymatic lipolysis of the incorporated short-chained triglyceride. The lipolytic products partition away from the nondigestible lipid, resulting in crystallization of the cubic-phase internal structure. Time-resolved small-angle X-ray scattering revealed the kinetics of the disorder-to-order transition, with cryo-transmission electron microscopy showing an absence of liposomes. The new approach offers a new sideways method for the generation of lipid-based nanostructured materials that avoids the problems of top-down and bottom-up approaches. © 2014 American Chemical Society.

DOI 10.1021/la5003447
Citations Scopus - 20Web of Science - 19
2014 Fong WK, Hanley TL, Thierry B, Tilley A, Kirby N, Waddington LJ, Boyd BJ, 'Understanding the photothermal heating effect in non-lamellar liquid crystalline systems, and the design of new mixed lipid systems for photothermal on-demand drug delivery', Physical Chemistry Chemical Physics, 16 24936-24953 (2014)

Lipid-based liquid crystalline systems are showing potential as stimuli-responsive nanomaterials, and NIR-responsive gold nanoparticles have been demonstrated to provide control o... [more]

Lipid-based liquid crystalline systems are showing potential as stimuli-responsive nanomaterials, and NIR-responsive gold nanoparticles have been demonstrated to provide control of transitions in non-lamellar phases. In this study, we focus on a deeper understanding of the photothermal response of both lamellar and non-lamellar phases, and new systems formed by alternative lipid systems not previously reported, by linking the photothermal heating to the bulk thermal properties of the materials. Dynamic photothermal studies were performed using NIR laser irradiation and monitoring the structural response using time resolved small angle X-ray scattering for the bulk phases and hexosomes. In addition, cryoFESEM and cryoTEM were used to visualise and assess the effect of GNR incorporation into hexagonal phase nanostructures. The ability of the systems to respond to photothermal heating was correlated with the thermal phase behaviour and heat capacities of the different structures. Access to alternative phase transitions in these systems and understanding the likely photothermal response will facilitate different modes of application of these hybrid nanomaterials for on-demand drug delivery applications. © the Partner Organisations 2014.

DOI 10.1039/c4cp03635b
Citations Scopus - 15Web of Science - 15
2013 Tangso KJ, Fong WK, Darwish T, Kirby N, Boyd BJ, Hanley TL, 'Novel spiropyran amphiphiles and their application as light-responsive liquid crystalline components', Journal of Physical Chemistry B, 117 10203-10210 (2013)

Light-responsive materials formed by liquid crystalline lipids in water have potential application to drug delivery through inclusion of photochromic additives such as spiropyran.... [more]

Light-responsive materials formed by liquid crystalline lipids in water have potential application to drug delivery through inclusion of photochromic additives such as spiropyran. A series of novel analogues of spiropyran (SP) have been synthesized with an SP headgroup that possess a C8 (SP-OC), C12 (SP-L), and C16 (SP-P) tail to probe the influence of the length of the hydrophobic tail on their physicochemical properties and effect on behavior in liquid crystal matrices with a view to application as stimulus-responsive elements on ultraviolet irradiation. In addition, compounds possessing an oleyl (SP-OL) and phytanyl (SP-PHYT) tail, to mimic those of the "parent" reverse bicontinuous cubic (V2) phase forming lipids, glyceryl monooleate (GMO) and phytantriol, were also prepared. The photochromic compounds were characterized by their melting points and photophysical behavior in solution using techniques including hot stage microscopy (HSM), differential scanning calorimetry (DSC), and UV-visible spectroscopy. Their effect on the equilibrium nanostructure of bulk V 2 phases and phase-switching kinetics after exposure to UV light was assessed using small-angle X-ray scattering (SAXS). The melting point of the SP derivatives decreased linearly with increasing chain length, which suggests that interactions between the head groups governed their melting point, rather than the van der Waals interactions between the tails. Changing the R group did not influence the equilibrium rate constants for the isomerization of SP. Phase transition temperatures of liquid crystalline (LC) matrices were influenced significantly by incorporation of the SP derivatives and were greatest when the photochromic compound possessed an intermediate tail length substituent compared to the short alkyl or bulkier moieties. The level of disruption of lipid packing, and hence phase structure, were dependent on the duration of UV exposure. © 2013 American Chemical Society.

DOI 10.1021/jp403840m
Citations Scopus - 24Web of Science - 23
2012 Fong WK, Hanley TL, Thierry B, Kirby N, Waddington LJ, Boyd BJ, 'Controlling the nanostructure of gold nanorod-lyotropic liquid-crystalline hybrid materials using near-infrared laser irradiation', Langmuir, 28 14450-14460 (2012)

Lipid-based liquid-crystalline matrixes provide a unique prospect for stimuli-responsive nanomaterials, attributed to the ability to effect self-assembly of the lipids at the mole... [more]

Lipid-based liquid-crystalline matrixes provide a unique prospect for stimuli-responsive nanomaterials, attributed to the ability to effect self-assembly of the lipids at the molecular level. Differences in liquid crystal nanostructure have previously been shown to change drug diffusion and hence release, with research progressing toward the use of in situ changes to nanostructure to control drug release. Toward this goal, we have previously communicated the ability to switch between nonlamellar structures using gold nanorod (GNR)-phytantriol-based liquid-crystalline hybrid nanomaterials as near-infrared light responsive systems (Fong et al. Langmuir2010, 26, 6136-6139). In this study, the effect of laser activation on matrix nanostructure with changes in a number of system variables including lipid composition, GNR aspect ratio, GNR concentration, and laser pulse time were investigated. The nanostructure of the matrix was followed using small-angle X-ray scattering, while both cryoFESEM and cryoTEM were used to visualize the effect of GNR incorporation into the liquid crystal nanostructure. The system response was found to be dependent on all variables, thus demonstrating the potential of these nanocomposite materials as reversible "on-demand" drug delivery applications. © 2012 American Chemical Society.

DOI 10.1021/la302901q
Citations Scopus - 34Web of Science - 32
2012 Fong WK, Malic N, Evans RA, Hawley A, Boyd BJ, Hanley TL, 'Alkylation of spiropyran moiety provides reversible photo-control over nanostructured soft materials', Biointerphases, 7 (2012)

The purpose of this study was to create a light responsive nanostructured liquid crystalline matrix using a novel alkylated spiropyran photochromic molecule (spiropyran laurate, S... [more]

The purpose of this study was to create a light responsive nanostructured liquid crystalline matrix using a novel alkylated spiropyran photochromic molecule (spiropyran laurate, SPL) as a light activated drug delivery system. The liquid crystal matrix, prepared from phytantriol, responds reversibly to changes in photoisomerism of SPL on irradiation, switching between the bicontinuous cubic and the reversed hexagonal liquid crystal structures, a change previously shown to dramatically alter drug release rate. In contrast, the non-derivatized spiropyran and spirooxazine photochromic compounds do not sufficiently disrupt the matrix on isomerization to induce the phase change. Thus, novel alkylated spiropyran has the potential to be an effective agent for use in liquid crystalline systems for reversible 'on-demand' drug delivery applications. © The Author(s) 2012.

DOI 10.1007/s13758-011-0003-9
Citations Web of Science - 21
2012 Fong WK, Malic N, Evans RA, Hawley A, Boyd BJ, Hanley TL, 'Alkylation of spiropyran moiety provides reversible photo-control over nanostructured soft materials', Biointerphases, 7 1-5 (2012)

The purpose of this study was to create a light responsive nanostructured liquid crystalline matrix using a novel alkylated spiropyran photochromic molecule (spiropyran laurate, S... [more]

The purpose of this study was to create a light responsive nanostructured liquid crystalline matrix using a novel alkylated spiropyran photochromic molecule (spiropyran laurate, SPL) as a light activated drug delivery system. The liquid crystal matrix, prepared from phytantriol, responds reversibly to changes in photoisomerism of SPL on irradiation, switching between the bicontinuous cubic and the reversed hexagonal liquid crystal structures, a change previously shown to dramatically alter drug release rate. In contrast, the non-derivatized spiropyran and spirooxazine photochromic compounds do not sufficiently disrupt the matrix on isomerization to induce the phase change. Thus, novel alkylated spiropyran has the potential to be an effective agent for use in liquid crystalline systems for reversible 'on-demand' drug delivery applications. © The Author(s) 2012.

Citations Scopus - 21
2011 Phan S, Fong WK, Kirby N, Hanley T, Boyd BJ, 'Evaluating the link between self-assembled mesophase structure and drug release', International Journal of Pharmaceutics, 421 176-182 (2011)

Lipid-based liquid crystalline materials are of increasing interest for use as drug delivery systems. The intricate nanostructure of the reversed bicontinuous cubic (V2) and inver... [more]

Lipid-based liquid crystalline materials are of increasing interest for use as drug delivery systems. The intricate nanostructure of the reversed bicontinuous cubic (V2) and inverse hexagonal (H2) liquid crystal matrices have been shown to provide diffusion controlled release of actives of varying size and polarity. In this study, we extend the understanding of release to other self-assembled phases, the micellar cubic phase (I 2) and inverse micelles (L2). The systems are comparable as they were all prepared from the one lipid, glyceryl monooleate (GMO), which sequentially forms all four phases with increasing hexadecane (HD) content in excess water. Phase identity was confirmed by small angle X-ray scattering (SAXS). SAXS data indicated that four mesophases were formed with increasing HD content at 25 °C: V2 phase (Pn3m space group) formed at 0-4% (w/w) HD, H2 phase formed at 4-25% (w/w) HD, I2 phase (Fd3m space group) formed at 25-40% (w/w) HD and finally L2 phase formed at >40% (w/w) HD. Analogous compositions using phytantriol rather than GMO as the core lipid did not produce the I2 phase, with only V 2 to H2 to L2 transitions being apparent with increasing HD concentration. In order to relate the liquid crystal phase structure to drug release rate, in vitro release tests were conducted by incorporating radio-labelled glucose as a model hydrophilic drug into the four GMO-based mesophases. It was found that the drug release followed first-order diffusion kinetics and was fastest from V2 followed by L2, H2, and I2. Drug release was shown to be significantly faster from bicontinuous cubic phase than the other mesophases, indicating that the state of the water compartments, whether open or closed, has a great influence on the rate of drug release. It is envisioned that liquid crystalline mesophases with slower release characteristics will more likely have potential applications as sustained release drug delivery systems, and hence that the bicontinuous cubic phase is not necessarily the best choice for a sustained release matrix. © 2011 Elsevier B.V. All rights reserved.

DOI 10.1016/j.ijpharm.2011.09.022
Citations Scopus - 123Web of Science - 117
2010 Fong WK, Hanley TL, Thierry B, Kirby N, Boyd BJ, 'Plasmonic nanorods provide reversible control over nanostructure of self-assembled drug delivery materials', Langmuir, 26 6136-6139 (2010)

The nanostructure of mesophase liquid crystals prepared from amphiphilic lipids controls the rate of release of incorporated agents from the material, such as drug molecules, and ... [more]

The nanostructure of mesophase liquid crystals prepared from amphiphilic lipids controls the rate of release of incorporated agents from the material, such as drug molecules, and reversible transition between different nanostructures essentially provides an "on-off" switch for release (Fong, W.-K.; Hanley, T.; Boyd, B. J. J. Controlled Release 2009, 135, 218-226). In this study, the incorporation of plasmonic hydrophobized gold nanorods (GNRs) permits reversible manipulation of nanostructure on-demand, by irradiation of the matrix using a near-infrared laser. Synchrotron small-angle X-ray scattering was used to probe the kinetics of the response of nanostructure to laser irradiation, and the specificity of the approach is shown by the lack of response in the absence of nanorods, or for GNR whose dimensions are not matched to the specific wavelength of the incident light. © 2010 American Chemical Society.

DOI 10.1021/la100644s
Citations Scopus - 64Web of Science - 59
2009 Fong WK, Hanley T, Boyd BJ, 'Stimuli responsive liquid crystals provide 'on-demand' drug delivery in vitro and in vivo', Journal of Controlled Release, 135 218-226 (2009)

Lipid-based liquid crystalline materials have been proposed as controlled drug delivery systems. Differences in liquid crystal nanostructure have previously been shown to change d... [more]

Lipid-based liquid crystalline materials have been proposed as controlled drug delivery systems. Differences in liquid crystal nanostructure have previously been shown to change drug diffusion and hence release, however there has been little progress towards the use of in situ changes to nanostructure to control drug release. In this study, phytantriol and glyceryl monooleate-based bicontinuous cubic (Q2) and inverse hexagonal (H2) nanostructures have been designed to allow change to the nanostructure in response to external change in temperature, with a view to controlling drug release rates in vivo. Changes to nanostructure with temperature were confirmed by crossed polarised optical microscopy and small angle X-ray scattering. Phytantriol containing 3% (w/w) vitamin E acetate provided the necessary phase transition behaviour to progress this system to in vitro release and in vivo proof of concept studies. Using glucose as a model hydrophilic drug, drug diffusion was shown to be reversible on switching between the H2 and Q2 nanostructures at temperatures above and below physiological temperature respectively. An in vivo proof of concept study in rats showed that after subcutaneous administration of these materials, the changes in nanostructure induced by application of a heat or cool pack at the injection site stimulated changes in drug release from the matrix anticipated from in vitro release behaviour, thereby demonstrating the potential utility of these systems as 'on demand' drug release delivery vehicles. © 2009 Elsevier B.V. All rights reserved.

DOI 10.1016/j.jconrel.2009.01.009
Citations Scopus - 195Web of Science - 188
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Grants and Funding

Summary

Number of grants 2
Total funding $511,000

Click on a grant title below to expand the full details for that specific grant.


20171 grants / $211,000

Postdoctoral Research Fellowship for Women$211,000

Funding body: Swiss National Science Foundation (SNSF)

Funding body Swiss National Science Foundation (SNSF)
Project Team

Prof. Alke Fink, Prof. Barbara Rothen

Scheme Project grant
Role Lead
Funding Start 2017
Funding Finish 2018
GNo
Type Of Funding C3232 - International Govt - Other
Category 3232
UON N

20141 grants / $300,000

Victorian Postdoctoral Research Fellowship$300,000

Three year postdoctoral fellowship - 2014-16 were spent at ETH Zurich, 2016-17 at Monash University (Pharmacy)

Funding body: Victorian Department of Business and Innovation

Funding body Victorian Department of Business and Innovation
Project Team

Prof. Raffaele Mezzenga (ETH Zurich), Prof. Ben J. Boyd

Scheme Research Project
Role Lead
Funding Start 2014
Funding Finish 2017
GNo
Type Of Funding C2210 - Aust StateTerritoryLocal - Own Purpose
Category 2210
UON N
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Research Supervision

Number of supervisions

Completed2
Current0

Past Supervision

Year Level of Study Research Title Program Supervisor Type
2018 PhD Near-Infrared Light Activated Lipid-Based Drug Delivery Systems for the Treatment of Age-Related Macular Degeneration Pharmacy, Monash University Co-Supervisor
2017 Honours Investigation of malonic additives as stimuli responsive components in meso Pharmacy, Monash University Principal Supervisor
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Dr Khay Fong

Position

Lecturer
School of Environmental and Life Sciences
Faculty of Science

Contact Details

Email khay.fong@newcastle.edu.au
Phone (02) 4921 7449
Link Twitter

Office

Room CH216
Building Chemistry
Location Callaghan
University Drive
Callaghan, NSW 2308
Australia
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