Endoscopic submucosal dissection is an established method for the removal of early cancers and large lesions from the gastrointestinal tract but is faced with the risk of perforation. To decrease this risk, a submucosal fluid cushion (SFC) is needed clinically by submucosal injection of saline and so on to lift and separate the lesion from the muscular layer. Some materials have been tried as the SFC so far with disadvantages. Here, we proposed a thermogel generated by the “block blend” strategy as an SFC. This system was composed of two amphiphilic block copolymers in water, so it was called a “block blend”. We synthesized two non-thermogellable copolymers poly(d,l-lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(d,l-lactide-co-glycolide) and blended them in water to achieve a sol–gel transition upon heating in both pure water and physiological saline. We explored the internal structure of the resultant thermogel with transmission electron microscopy, three-dimensional light scattering, 13C NMR, fluorescence resonance energy transfer, and rheological measurements, which indicated a percolated micelle network. The biosafety of the synthesized copolymer was preliminarily confirmed in vitro. The main necessary functions as an SFC, namely, injectability of a sol and the maintained mucosal elevation as a gel after injection, were verified ex vivo. This study has revealed the internal structure of the block blend thermogel and illustrated its potential application as a biomaterial. This work might be stimulating for investigations and applications of intelligent materials with both injectability and thermogellability of tunable phase-transition temperatures.
Topochemical reactions can be effectively conducted without additional reagents and solvation requirements. Hence, they are attractive in various fields of modern chemistry. However, there remains a lack of ways to precisely control the degree upon topochemical polymerization or oligomerization. As compared with yielded π-structured polymers, a slight difference in repeating unit of their oligomeric counterparts can normally connect to distinct visualized optoelectronic properties in the UV−vis region. Therefore, we herein report that the well-selected biomacromolecular templates were straightforwardly employed to attain a precise control of topochemical photooligomerization degree for a series of uniform oligomeric π-functional materials. A diphenyldiacetylene prototype was designed and electrostatically interacted with BSA (albumin from bovine serum), DNA (calf thymus), and HS (heparin sodium), and their binding constant exhibited a progressive order of magnitude. In this way, photooligomerization control for uniquely forming corresponding dimeric and trimeric oligodiacetylenes can be successfully achieved upon photoirradiation with the template optimized from the perspective of adjustable dynamic equilibrium. Furthermore, two of the oligodiacetylene species reveal blue and yellow fluorescence and therefore can be applied into selective and multichannel bioimaging with good biocompatibility on account of their biomacromolecular templates, featuring the advantage of obtaining species with repeating-unit difference for material applications.
Bone tissue engineering, as an important and attractive multidisciplinary field, affords a feasible strategy for large bone defects which are difficult to heal without clinical intervention. However, the complicated requirements...
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