More Like this

1. Feasibility and Compatibility of a Biomass Capsule System in Self-Healing Concrete

   https://doi.org/10.3390/ma14040958  

   Sinha, Arkabrata ; Wang, Qi ; Wei, Jianqiang ( February 2021 , Materials)

   null (Ed.)

   Cracking can facilitate deteriorations of concrete structures via various mechanisms by providing ingress pathways for moisture and aggressive chemicals. In contrast to conventional maintenance methods, self-healing is a promising strategy for achieving automatic crack repair without human intervention. However, in capsule-based self-healing concrete, the dilemma between capsules’ survivability and crack healing efficiency is still an unfathomed challenge. In this study, the feasibility of a novel property-switchable capsule system based on a sustainable biomass component, polylactic acid, is investigated. Capsules with different geometries and dimensions were studied focusing on the compatibility with concrete, including survivability during concrete mixing, influence on mortar and concrete properties, and property evolution of the capsules. The results indicate that the developed elliptical capsules can survive regular concrete mixing with a survival ratio of 95%. In concrete containing 5 vol.% of gravel-level capsules, the compressive strength was decreased by 13.5% after 90 days, while the tensile strength was increased by 4.8%. The incorporation of 2 vol.% of sand-level capsules did not impact the mortar strength. Degradation and switchable properties triggered by the alkaline matrix of cement were observed, revealing the potential of this novel biomass capsule system in achieving both high survivability and self-healing efficiency in concrete. 

   more » « less
2. Core–shell droplets and microcapsules formed through liquid–liquid phase separation of a colloid–polymer mixture

   https://doi.org/10.1039/D1SM01091C  

   Dang, Steven ; Brady, John ; Rel, Ryle ; Surineni, Sreenidhi ; O’Shaughnessy, Conor ; McGorty, Ryan ( September 2021 , Soft Matter)

   Microcapsules allow for the controlled containment, transport, and release of cargoes ranging from pharmaceuticals to fragrances. Given the interest from a variety of industries in microcapsules and other core–shell structures, a multitude of fabrication strategies exist. Here, we report on a method relying on a mixture of temperature-responsive microgel particles, poly( N -isopropylacrylamide) (pNIPAM), and a polymer which undergo fluid–fluid phase separation. At room temperature this mixture separates into colloid-rich (liquid) and colloid-poor (gas) fluids. By heating the sample above a critical temperature where the microgel particles shrink dramatically and develop a more deeply attractive interparticle potential, the droplets of the colloid-rich phase become gel-like. As the temperature is lowered back to room temperature, these droplets of gelled colloidal particles reliquefy and phase separation within the droplet occurs. This phase separation leads to colloid-poor droplets within the colloid-rich droplets surrounded by a continuous colloid-poor phase. The gas/liquid/gas all-aqueous double emulsion lasts only a few minutes before a majority of the inner droplets escape. However, the colloid-rich shell of the core–shell droplets can solidify with the addition of salt. That this method creates core–shell structures with a shell composed of stimuli-sensitive microgel colloidal particles using only aqueous components makes it attractive for encapsulating biological materials and making capsules that respond to changes in, for example, temperature, salt concentration, or pH. 

   more » « less
3. Shell buckling for programmable metafluids

   https://doi.org/10.1038/s41586-024-07163-z  

   Djellouli, Adel ; Van Raemdonck, Bert ; Wang, Yang ; Yang, Yi ; Caillaud, Anthony ; Weitz, David ; Rubinstein, Shmuel ; Gorissen, Benjamin ; Bertoldi, Katia ( April 2024 , Nature)

   The pursuit of materials with enhanced functionality has led to the emergence of metamaterials—artificially engineered materials whose properties are determined by their structure rather than composition. Traditionally, the building blocks of metamaterials are arranged in fixed positions within a lattice structure. However, recent research has revealed the potential of mixing disconnected building blocks in a fluidic medium. Inspired by these recent advances, here we show that by mixing highly deformable spherical capsules into an incompressible fluid, we can realize a ‘metafluid’ with programmable compressibility, optical behaviour and viscosity. First, we experimentally and numerically demonstrate that the buckling of the shells endows the fluid with a highly nonlinear behaviour. Subsequently, we harness this behaviour to develop smart robotic systems, highly tunable logic gates and optical elements with switchable characteristics. Finally, we demonstrate that the collapse of the shells upon buckling leads to a large increase in the suspension viscosity in the laminar regime. As such, the proposed metafluid provides a promising platform for enhancing the functionality of existing fluidic devices by expanding the capabilities of the fluid itself. 

   more » « less
4. Nanofiller-Enhanced Soft Non-Gelatin Alginate Capsules for Modified Drug Delivery

   https://doi.org/10.3390/ph14040355  

   Joshi, Sameer ; Sahu, Rajnish ; Dennis, Vida A. ; Singh, Shree R. ( April 2021 , Pharmaceuticals)

   Capsules are one of the major solid dosage forms available in a variety of compositions and shapes. Developments in this dosage form are not new, but the production of non-gelatin capsules is a recent trend. In pharmaceutical as well as other biomedical research, alginate has great versatility. On the other hand, the use of inorganic material to enhance material strength is a common research topic in tissue engineering. The research presented here is a combination of qualities of alginate and montmorillonite (MMT). These two materials were used in this research to produce a soft non-gelatin modified-release capsule. Moreover, the research describes a facile benchtop production of these capsules. The produced capsules were critically analyzed for their appearance confirming resemblance with marketed capsules, functionality in terms of drug encapsulation, as well as release and durability. 

   more » « less
5. Extraordinarily long development of the Antarctic gastropod Antarctodomus thielei (Neogastropoda: Buccinoidea)

   https://doi.org/10.1093/mollus/eyz015  

   Moran, A. L. ; Harasewych, M. G. ; Miller, B. A. ; Woods, H. A. ; Tobalske, B. W. ; Marko, P. B. ( August 2019 , Journal of Molluscan Studies)

   Antarctic animals share many traits that are attributed to evolution in a stable, extremely cold climate. Among invertebrates, development is exceptionally slow, making observational studies of development logistically challenging, particularly when conducted under natural conditions in the field. Using multiple deployments to McMurdo Station, Antarctica, we characterized the development, in the field, of an unidentified buccinoidean gastropod species with encapsulated development. Thirteen egg capsules collected at Granite Harbor, McMurdo Sound, Ross Sea, were attached to natural rock and outplanted at a depth of ~25 m at the base of the McMurdo Intake Jetty on 2 December 2007, photographed on 5 October 2011 and 6 September 2012 and then returned to the laboratory on 27 November 2015. In 2015, four capsules were open and empty, five were open and contained a single large hatchling and the remaining four capsules were intact but not open, each containing a single large juvenile snail. To identify the developing embryos, we sequenced mitochondrial cytochrome c oxidase subunit I (COI) from two hatchlings and compared those sequences with those from adults collected near the egg mass, as well as with sequences of other buccinoideans from GenBank. Based on the close match between hatchling and adult COI sequences (hatchling sequences differed from those of an adult at only 2 of 658 nucleotide positions), we identified the embryos as Antarctodomus thielei (Powell, 1958)). The egg mass morphology and development of this species have not been previously described. Our study shows that A. thielei has a development time of more than 8 years, which is the longest measured for any gastropod.

    

   more » « less