Molecular Engineering: From Molecules to Medicine
Authors: Can Zhang, Xiaohu Gao
Journal: Advanced Healthcare Materials (2019)

Molecular engineering is a bottom-up mode of engineering for making functional materials and devices using molecules and atoms as building blocks. It represents a fusion of diverse scientific disciplines, including physics, chemistry, chemical engineering, materials science, bioengineering, electrical engineering, mechanical engineering, biology, and artificial intelligence. It also shares several fundamental concepts with nanotechnology, as Dr. Richard Feynman described in his famous speech, There's Plenty of Room at the Bottom. This emerging field is finding impactful applications in energy and medicine, and has been recognized by the National Academy of Engineering as one of the most critical areas to future economic, environmental, and medical health of the USA. Towards medicine, molecular engineering has the potential to transform diseases diagnosis, prognosis, and treatment. New insights and advances are frequently being reported and discussed at major society meetings. For example, an international scientific conference, the 3rd Chinese American Society of Nanomedicine and Nanobiotechnology (CASNN) annual meeting, held in Nanjing, China in the summer of 2018 provided such a discussion forum. Approximately 50 speakers shared their findings in the field of molecular engineering with over 500 conference attendees. This special issue of Advanced Healthcare Materials presents excellent contributions (six original research articles and six review articles) from the conference participants. Among the Review articles, Professor Suzie Pun at the University of Washington and Professor Chun Wang at the University of Minnesota discuss the molecule engineering principles for synthesis of block copolymers with segmented backbones and non-aqueous supramolecular soft materials, respectively, with the primary applications in drug delivery (see article numbers 1800861 and 1800908). Professor Hongyu Chen at Nanjing University of Technology summarizes the strategies to incorporate drug molecules into nanoparticles for improved pharmacokinetics and pharmacodynamics (article number 1801002). Systematic comparison across the various drug loading strategies provides a clear visualization of their strengths and weaknesses. Besides synthetic materials, natural and biomimetic functional materials are also of significant interest due to their diverse functionalities and biocompatibility. Professor Yi Lu at the University of Illinois Urbana-Champaign describes recent breakthroughs in designing and engineering functional nucleic acid (FNA)-based nanomaterials (article number 1801158). The unique target-recognition and catalytic activity of FNAs enable the design and production of numerous intelligent nanoprobes for intracellular imaging, drug delivery, in vivo imaging, and cancer therapy. Similarly, Professor Chalet Tan at the University of Mississippi discusses another natural nanoparticle, exosomes. Exosomes are cell-derived nanovesicles encapsulating and transferring molecular cargos to recipient cells and mediating intercellular communications. Recent progresses in understanding of circulating exosomes as cancer biomarkers and the developing exosome-based drug delivery platforms are covered. Beyond applications in cancer that have been studied quite extensively, molecular engineering has started to expand into neuroengineering as well (see article number 1801268). Professor Gang Han at the University of Massachusetts discusses the emerging application of near infrared (NIR) probes for optogenetics (article number 1801132). Compared to the conventional visible light-triggered optogenetic approaches, NIR light offers improved tissue penetration depth, potentially allowing wireless modulation of cell signaling pathways. Among the original research articles, Professor Chuanbing Tang at the University of South Carolina and Professor Gang Zheng at the University of Toronto report the combinations of metallopolymer-antibiotic bioconjugates with gold nanoparticles as an antibacterial agent (see article number 1800854), and texaphyrin-phospholipid nanoparticles with metal ions for multimodal molecular imaging (see article number 1800857), respectively. Towards drug delivery, Professor Younan Xia at Georgia Tech reports an interesting nanosystem based on Au nanocages (AuNCs) and a phase changing material (PCM) for delivering salt ions into cancer cells, thereby triggering cell death upon NIR light irradiation (see article number 1801113). For macrobiomolecule delivery, Professor Qiaobing Xu at Tuffs University has devised a simple and clever idea to bring proteins and enzymes inside cells (see article number 1800996). Non-cationic lipidoid nanoparticles (LNPs) decorated with metal chelators can carry any protein with a his-tag across the cell membrane, which opens new opportunities for biological therapeutics including the powerful CRISPR/Cas9 technology. For the same goal of macrobiomolecule delivery, we report a different approach combining Flash nanoprecipitation (FNP) and hydrophobic ion pairing (HIP) (article number 1801010). In contrast to many proof-of-concept nanoparticle production and microfluidic approaches, the FNP-based biologics formulation is fully automated and scalable, enhancing the potential of technology translation. An example of molecular engineering for diagnostics is illustrated by a contribution from Professor Hongwei Duan at the Nanyang Technological University in Singapore (see article number 1801022). His team demonstrate a micrometer-sized magnetic mixer to help eliminate or reduce the diffusion limitation of small-volume assays such as microarrays and microfluidics. This general approach improves assay sensitivity, kinetics, and reproducibility. Overall, molecular engineering is a young and rapidly growing field at the cross-section of science, engineering, and medicine. The excellent examples in this Special Issue contributed by world leading researchers provide a survey of the research today and inspiration for a new generation of engineers of tomorrow. With continued efforts in this new mode of engineering, rapid translation of molecular advances into medical breakthroughs can be expected. Can Zhang is a professor in the Academic Institute of Pharmaceutical Science at China Pharmaceutical University (CPU), and has served as the dean of the Academic Institute of Pharmaceutical Sciences and the director of the Center of Advanced Pharmaceuticals and Biomaterials at CPU. She received her Ph.D. degree in polymer chemistry and physics from Nanjing University. Her research focuses on biomaterials engineering, nanomedicine, molecular and cell therapy. Xiaohu Gao is a professor in the Department of Bioengineering at the University of Washington. He received his Ph.D. degree in bioanalytical chemistry from Indiana University, Bloomington, and his postdoctoral training from the Department of Biomedical Engineering at Georgia Tech and the Winship Cancer Institute at Emory University. His research interests include bionanotechnology, molecular engineering, molecular imaging, and therapeutics.