Assistant Professor,Hong Kong Polytechnic University
Dr. Xin Zhao is an Assistant Professor at the Department of Biomedical Engineering, the Hong Kong Polytechnic University (PolyU). She obtained her PhD at University College London, UK and postdoc training at Harvard University, USA, before joining PolyU. Her research interest is on Translational Regenerative Medicine, where she integrates multi-disciplinary approaches including material science, cell biology, engineering and medicine to modulate cell microenvironments, control cell behaviors and generate tissue-engineered organs, for addressing clinical issues.
So far, she has published >90 articles (with h-index of 33 in Google Scholar, 5 of which are ESI highly cited paper) in prestigious journals including Proc. Natl. Acad. Sci. USA, Chem. Rev., Mater. Today, Adv. Funct. Mater., Angew. Chem. Int. Ed., Biomaterials, Small. She has successfully attracted over 10 grants (⁓11 million) as principal investigator from the Hong Kong Research Grants Council (RGC), Health and Medical Research Fund (HMRF), Innovation and Technology Fund of Hong Kong (ITF), National Science Foundation of China (NSFC), Guangdong Basic and Applied Basic Research Foundation, private company, etc. She is a recipient of the Faculty Award of 2019 (only 3 were selected from over 150 academic staff of the Engineering Faculty of PolyU) and the Engineering Research Grant Achievement Award of 2019 (only 8 were selected from over 150 academic staff of the Engineering Faculty). With only 4 participants selected from Asia, she represented Hong Kong in the prestigious Asia Pacific Research Network Fellowship Program in 2018. In 2020, she also represented PolyU as the K. C. Wong Education Foundation visiting scholar to deliver talks in mainland China. Moreover, she has been shortlisted for the “Nature Research Awards for Inspiring Science” in 2019 (10 shortlisted from >150 applicants globally) and her project “Biomimicking Photocrosslinkable Nanocomposite Bone Graft” has won the Silver Medal at the Special Edition 2021 Inventions Geneva. She is also a founding editor of Engineered Regeneration, associate editor of Bio-Des. Manuf. and Biointerface Res Appl, and guest editor for 11 other journals.
Photocrosslinkable polymers are polymers that can be solidified from liquid upon light exposure. They have been employed to fabricate tissue engineered constructs due to the mild conditions for crosslinking, highly tunable mechanical and structural modifiability, printability, biodegradability and biocompatibility. These biomaterials can maintain their structural integrity after biofabrication and provide topological, biochemical, and physical cues to guide cellular behaviors by creating a biomimetic microenvironment.
The emphasis of this talk is placed on how photocrosslinkable polymers can be used to achieve regeneration of diseased or damaged tissues, for example, their fabrication into various scaffolds (electrospun fibers, microspheres, and 3D printed scaffolds) to reconstruct hard tissues like bone as well as soft tissues such as skin (Figure 1). Specifically, assisted by microfluidics, we have developed photocrosslinkable methacrylated gelatin (GelMA) based microspheres encapsulating human mesenchymal stem cells (MSCs) for bone repair1. Due to the mild crosslinking conditions, we found that the GelMA microspheres can provide a favourable micro-environment for MSC survival, spreading, migration, proliferation and osteogenesis. In another study, we prepared a periosteum mimicking bone aid (PMBA) by electrospinning photocrosslinkable GelMA with L-arginine-based unsaturated poly(ester amide) (Arg-UPEA), and methacrylated hydroxyapatite nanoparticles (nHAMA)2. Upon light exposure, the resultant hydrogel fibrous scaffolds can solidify within seconds. Via controlling the crosslinking density, we can control the scaffolds’ mechanical and degradation property. Additionally, the optimal scaffold was found to provide long-term structural and functional support and mediation of physiological activity. With the aid of 3D printing, we developed 3D bone scaffolds made of photocrosslinkable nanocomposite ink consisting of tri-block poly (lactide-co-propylene glycol-co-lactide) dimethacrylate (PmLnDMA, m and n respectively represent the unit length of propylene glycol and lactide) and nHAMA3. It is discovered that the nHAMA can rapidly interact with PmLnDMA upon light exposure within 140 seconds and form an inorganic-organic co-crosslinked nanocomposite network. This bone ink was found to provide good mechanical strength and bioactivity for bone regeneration.
Figure 1. Fabrication and application of photocrosslinkable polymers.