Wei Tao Group of Hong Kong University and Hong Liangzhi group of South China Institute of Technology: controlled solvent release of submicron capsules is realized for the first time through submicron low-permeability packaging technology of all silicon dioxide

Lead microcapsule technology has a good application prospect in the fields of drug delivery, agriculture and cosmetics However, most of the microcapsules reported in the literature have high permeability and the size is in the micron level, which greatly limits their application and packaging efficiency Recently, the research group of Professor Wei Tao, Department of chemistry, Chinese University Hong Kong and Professor Hong Liangzhi of South China University of Technology School of materials, using the hydrophobic modified ultrafine silica nanoparticles as the single emulsifier for the inverse Pickering emulsion, prepared the inverse Pickering with sub micron size Emulsion, and successfully prepared silica submicron capsules with this template, for the first time, the solvent controlled release of sub micron capsules was achieved The research results were published in the top Chemical Journal angel Chem Int ed (DOI: 10.1002 / anie 201805968) under the title of "all silicon submicrometer compounds for cargo protection and tunable release" The first author of this paper is Jiang hang, a Ph.D student in the Department of chemistry, Chinese University of Hong Kong, and Li Yunxing, an associate professor in the school of chemistry and materials engineering, Jiangnan University Prof Wei Tao, Ph.D., Professor, doctoral supervisor, Chinese University of Hong Kong In 2003, he received his Ph.D in chemistry from the Chinese University of Hong Kong; from 2003 to 2005, he worked for BASF company in Germany, and from July to December 2005, he worked as a postdoctoral researcher at the University of Minnesota in the United States; from January 2006 to December 2007, he worked as an assistant research professor and deputy editor in chief assistant of macrolecules at the Chinese University of Hong Kong In 2008, he was employed as an assistant professor in the Department of chemistry of the Chinese University of Hong Kong, and was promoted to associate professor and professor in 2012 and 2017 respectively The main research areas include: design and synthesis of polymers, colloids, soft materials and their interaction characterization, synthesis and self-assembly of nanoparticles, self-assembly theory and methods, preparation and application of Pickering emulsion, biological bone materials and coating applications In recent years, Professor Wei Tao has published more than 100 papers in international core academic journals such as angel Chem Int ed biomaterials, ACS appl Mater Inter., macrolecules, etc Prof Hong Liangzhi, associate professor of South China University of technology, master's supervisor He received his bachelor's degree from Lanzhou University in 2000, his master's degree from Zhongshan University in 2003, his doctor's degree from the Chinese University of Hong Kong in 2007, his postdoctoral research from the Chinese University of Hong Kong in 2007-2008, his postdoctoral research from Queen's University of Canada in 2008-2010, and his research assistant professor from the Chinese University of Hong Kong in 2010-2011 He joined the school of materials, South China University of technology The main research directions are the preparation of functional colloidal particles and their interface assembly, the synthesis of functional polymers and surface modification Cutting edge scientific research achievements: through the submicron low-permeability encapsulation technology of all silica, the solvent controlled release microcapsule technology of submicron capsules has been widely used in the protection and release of active substances for the first time Compared with the traditional large-scale drug packaging, the micro scale packaging technology not only has higher packaging efficiency, but also its shell structure can protect the internal active substances from the interference and destruction of external factors Nanoparticles can replace traditional surfactants to stabilize water and oil emulsion (also known as Pickering emulsion) Pickering emulsion has high stability and can be used as a microcapsule template However, there are few practical applications of microcapsules based on this technology Pickering emulsion is composed of colloidal nanoparticles stabilized water and oil system Nanoparticles will be arranged at the water oil bending interface to achieve stable emulsification, which may lead to loose arrangement or arrangement of gaps between nanoparticles, leading to leakage of active substances in the emulsion Moreover, the release of most microcapsules depends on the explosive release caused by the self diffusion of the content or the rupture of microcapsules Therefore, most of the active substances will be released in a short time, which can not meet the requirements of practical application To cope with this challenge, the Wei Tao research team of the Department of chemistry of Chinese University Hong Kong and Hong Liang Chi research team of South China University of Technology School of materials used hydrophobic modified silica nanoparticles as emulsified particles of Pickering emulsion, not only successfully prepared a stable silica gel nanoparticle stabilized Pickering emulsion (water in oil), but also successfully used sol - silica gel microcapsules were prepared by gel reaction, and the size of the microcapsules was controllable (300nm~2 m) Fig 1 preparation process of silica microcapsule (source: Angew Chem.Int Ed.) the authors used different sizes of silica nanoparticles to obtain different sizes of oil in water Pickering emulsions, thus controlling the size of silica microcapsules In addition, all silica materials also give silica microcapsules strong mechanical strength and controllable shell thickness, so as to better protect the inclusion Fig 2 Electron micrograph of microcapsules with different sizes and shell thickness (source: angelw Chem Int ed.) Not only that, hydrophobic silica nanoparticles on the surface of microcapsules are not easy to be soaked by water, which can effectively block the material exchange inside and outside the microcapsules in pure water, so as to achieve the goal of low permeability When ethanol or surfactant is added to the water, it can effectively improve the wetting relationship between the external aqueous phase and the surface of silica nanoparticles, promote the spreading of aqueous solution on its surface and invade the inside of the capsule, thus leading to the release of the response This work has not only developed a simple method for preparing submicron reverse phase Pickering emulsion, but also demonstrated the very interesting release of ethanol or surfactant, which has great application prospects in the fields of acute alcoholism, cosmetics, biphasic catalysis and other fields Figure 3 Ethanol and surfactant stimulated release (source: angelw Chem Int ed.) today, people and scientific research are getting more and more attention in economic life China ushers in the "node of science and technology explosion" Behind the progress of science and technology is the work of countless scientists In the field of chemistry, in the context of the pursuit of innovation driven, international cooperation has been strengthened, the influence of Returned Scholars in the field of R & D has become increasingly prominent, and many excellent research groups have emerged in China For this reason, CBG information adopts the 1 + X reporting mechanism CBG information, chembeangoapp, chembeango official microblog, CBG wechat subscription number and other platforms jointly launch the column of "people and scientific research", approach the domestic representative research group, pay attention to their research, listen to their stories, record their demeanor, and explore their scientific research spirit.