Our lab has expertise in the rational design of hydrogels on multiple length scales (from the bulk to the nanoscale) for targeted applications. We have particular interest in the synthesis and characterization of injectable or in situ-gelling hydrogels that spontaneously crosslink upon mixing two or more functional precursor polymers, allowing us to create mechanically strong and tunable hydrogels that can be injected, printed, dip-coated, electrospun, cryogelled, or 3D printed on demand to create functional implants, coatings, and scaffolds with specific properties. Engineering the chemical composition and/or morphology of the precursor polymers, or creating functional nanocomposites again by simple mixing of the nanoparticle additive, leads to hydrogel properties otherwise difficult to achieve using conventional gelation processes. We especially aim to harness the properties of smart materials whose properties can change in response to changes in their environment to create new types of degradable, printable, and porous structures that enable faster response times, improved bioactive encapsulation, and tunable cell responses. We also regularly integrate statistical optimization approaches to rapidly optimize hydrogel compositions for target applications and advanced characterization techniques such as small angle neutron scattering to comprehensively understand structure-property correlations in hydrogel materials.
Microgels & Nanogels
Our lab is a leader in understanding the structure and properties of smart environmentally-responsive microgels and nanogels. Our current efforts in this area are focused on developing new assembly and/or synthetic strategies to fabricate monodisperse (uniform size) micro/nanogels that maintain rapid responses to temperature, pH, and/or magnetic stimuli while also effectively degrading over time, a key barrier to the use of most current micro/nanogels in biomedical applications. We are also developing new nanocluster nanogel structures in which a single micro/nanogel is composed of many smaller nanogel building blocks, a morphology that offers a host of novel physical as well as biological properties for promoting tissue penetration without sacrificing long circulation times. More fundamental interests in this area include the investigation of how different micro/nanogel assembly strategies influence the internal microstructure of the micro/nanogels (and their resulting properties) and the prediction of smart micro/nanogel phase transitions using a combination of statistical and kinetic modeling approaches.
We work with multiple collaborators to develop new hydrogel/nanogel/soft nanoparticle-based drug delivery vehicles for treating a variety of diseases. Representative examples of ongoing projects include the fabrication of mucoadhesive self-assembled nanogels/nanoparticles for intranasal or front-of-the-eye delivery, injectable hydrogels for the delivery of anti-angiogenic proteins to the back of the eye, sprayable mucoadhesive hydrogels for the delivery of antipsychotic drugs from the nose to the brain, cancer microenvironment-triggerable nanogels and brush copolymer-based nanoparticles for improved chemotherapeutic delivery to tumours, antibiotic-impregnated porous hydrogel scaffolds for treating/preventing wound infections, and injectable lubricating hydrogels for treating osteoarthritis. In many cases, these projects are partnered with companies that have translational interests in the vehicles designed. In parallel, we work on designing next-generation “smart” delivery vehicles that leverage our designed degradable smart hydrogel technologies to enable pulsatile or triggered release of drugs “on-demand” upon the application of a magnetic field or ultrasound, facilitating chronotherapy and/or non-invasive local therapies while avoiding the need for repeated injections.
We aim to create new hydrogel-based scaffolds based on synthetic polymers and smart polymers that overcome the key limitations of existing tissue scaffold materials, including the frequent use of pore-forming additives that subsequently need to be removed from the scaffold prior to use (a step that is slow and potentially leads to residual toxicity) and the incompatibility of most scaffold fabrication processes to the direct integration of cells. In this context, we are developing new macroporous scaffold fabrication technologies including reactive electrospinning of hydrogel nanofibers in the direct presence of cells, supercritical fluids-based processing strategies for creating sterile crosslinked aerogels in a single step, 3D printing approaches that enable high-resolution printing of in situ-gelling bioinks with high cell compatibility, and the use of tissue-compatible blowing agents to enable the fabrication of macroporous injectable hydrogels via a single injection using a conventional syringe. We also work with both academic and industry collaborators to assess the potential of these new scaffolds for accelerating burn or abrasion wound healing, enabling functional cell delivery to the retina, and promoting muscle and neuronal tissue regeneration.
We aim to solve the “middle-man” problem of biosensing – the high non-specific adsorption of proteins and other components of complex biological media to sensor interfaces that results in high noise and thus poor sensitivities to the sensor target. We are developing new printing and dip-coating strategies that enable single-step functionalization of biosensor interfaces with highly adhesive protein-repellent polymer or hydrogel coatings, including conductive coatings to maintain good electrochemical biosensor performance. We are further leveraging the capacity of hydrogel-based coatings/printed arrays to encapsulate cells and/or sensing biomolecules (e.g. DNA or enzymes) in networks with controllable pore sizes to produce stable and size-selective biosensors that can enable the detection of only small molecules while excluding aggregates (as beneficial for early-stage drug discovery) and/or DNA sequences of particular lengths. Highly protein-repellent magnetic microgels are also under development to facilitate reduced fouling and improved ligand presentation in bead-based bioassays, leading to improved biosensor sensitivity. Collaborative applications in this area include the quantification and identification of bacteria loads in undiluted urine and point-of-care detection of viral loads.
We are developing soft nanoparticle and sprayable hydrogel formulations for improving the delivery of bioactives to plants, as is essential to maintain high crop yields under the combined threats of the global reduction in arable land and climate change. Our specific interest lies in improving the retention and penetrability, and thus the overall activity, of foliar (leaf) sprays. We are investigating how soft and hydrated nanoparticles can improve the transport of agrochemicals into and throughout the leaf, leveraging our capacity to control the size, hydration, and surface chemistry of micro/nanogels and soft nanoparticles. We are also designing nanocomposite sprayable hydrogel formulations that can enable prolonged agrochemical delivery to plants and/or enable pulsatile agrochemical activity upon repeated hydration cycles such as rain, irrigation, or morning dew.
We work with industry partners to develop new functional hydrogels for personal care applications, with a particular emphasis on the synthesis of superabsorbent hydrogels with improved swelling capacities, reduced preparation costs, and/or more renewable chemistries. We are also open to collaborations for developing new functional food, nutraceutical, and cosmetic hydrogel formulations.