Selectively Detachable Hydrogel Adhesion Enabled by Stimulus-Specific Cleavable Cross-Linkers
Yoon, Young Bin
;
Cho, In
;
Koo, Hye Been
, et al.
ACS Appl. Mater. Interfaces,2024,16(48):66738-66752.
DOI:
10.1021/acsami.4c15507
PubMed ID:
39565883
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Abstract: The development of detachable hydrogel adhesion presents an advancement in the fields of soft electronics and bioengineering as it offers additional functionalities to these applications. However, conventional methods typically rely on a single detachment trigger, so it is unclear whether unintentional detachment might occur in the specific environments of other detachment systems. This makes it difficult to directly introduce two independent detachment triggers directly. In this article, we present a strategy for selective detachable adhesion based on two types of cleavable cross-linkers, N,N'-bis(acryloyl)cystamine(BAC) and N,N′-(1,2-dihydroxyethylene)bis(acrylamide)(DHEBA), each with an independent cleavage trigger. BAC can be cleaved through the reduction of disulfide bonds using reducing agents, while DHEBA can be hydrolyzed through heating. We constructed stitching polymer networks for topological adhesion using two types of cleavable cross-linkers, allowing the networks to be selectively degraded depending on which cross-linker was used. Our findings show that the use of cleavable cross-linkers achieved selectively detachable adhesion in various hydrogels, with adhesion energy that reached up to 1223 J m?2 in polyacrylamide-alginate (PAAm-alginate) tough hydrogel. This strategy also proved versatile as it led to effective adhesion with various substrates, including aluminum, copper, glass, and polyester film (PET). Furthermore, we took advantage of the high programmability of this approach to construct hydrogel-based YES and AND logic gates, whose output changed depending on the applied input triggers. In addition, we designed a selective-release capsule model capable of dual-solution release, which emphasizes the potential of our strategy in creating programmable and responsive soft materials.
Keywords:
hydrogel ;
detachable hydrogel adhesion ;
cleavable cross-linker ;
hydrogel logic gates ;
selective-release capsule
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Human hand-inspired all-hydrogel gripper with a high load capacity formed by the split-brushing adhesion of diverse hydrogels
Hye Been Koo
;
Eunseok Heo
;
In Cho
, et al.
Mater. Horiz.,2023,10(6):2075-2085.
DOI:
10.1039/D2MH01309F
PubMed ID:
36920793
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Abstract: Human hands are highly versatile. Even though they are primarily made of materials with high water content, they exhibit a high load capacity. However, existing hydrogel grippers do not possess a high load capacity due to their innate softness and mechanical strength. This work demonstrates a human hand-inspired all-hydrogel gripper that can bear more than 47.6 times its own weight. This gripper is made of two hydrogels: poly(methacrylamide-co-methacrylic acid) (P(MAAm-co-MAAc)) and poly(N-isopropylacrylamide) (PNIPAM). P(MAAm-co-MAAc) is extremely stiff but becomes soft above its transition temperature. By taking advantage of the difference in the kinetics of the stiff–soft transition of P(MAAm-co-MAAc) hydrogels and the swelling–shrinking transition of PNIPAM hydrogels, this gripper can be switched between its stiff-bent and stiff-stretched states by simply changing the temperature. The assembly of these two hydrogels into a gripper necessitated the development of a new hydrogel adhesion method, as existing topological adhesion methods are not applicable to such stiff hydrogels. A new hydrogel adhesion method, termed split-brushing adhesion, has been demonstrated to satisfy this need. When applied to P(MAAm-co-MAAc) hydrogels, this method achieves an adhesion energy of 1221.6 J m[?2], which is 67.5 times higher than that achieved with other topological adhesion methods.
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In situ silver nanoparticle development for molecular-specific biological imaging via highly accessible microscopies
Dae-Hyeon Song
;
Chang Woo Song
;
Jinkyoung Chung
, et al.
Nanoscale Adv.,2023,5(6):1636-1650.
DOI:
10.1039/d2na00449f
PubMed ID:
36926569
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Abstract: In biological studies and diagnoses, brightfield (BF), fluorescence, and electron microscopy (EM) are used to image biomolecules inside cells. When compared, their relative advantages and disadvantages are obvious. BF microscopy is the most accessible of the three, but its resolution is limited to a few microns. EM provides a nanoscale resolution, but sample preparation is time-consuming. In this study, we present a new imaging technique, which we termed decoration microscopy (DecoM), and quantitative investigations to address the aforementioned issues in EM and BF microscopy. For molecular-specific EM imaging, DecoM labels proteins inside cells using antibodies bearing 1.4 nm gold nanoparticles (AuNPs) and grows silver layers on the AuNPs' surfaces. The cells are then dried without buffer exchange and imaged using scanning electron microscopy (SEM). Structures labeled with silver-grown AuNPs are clearly visible on SEM, even they are covered with lipid membranes. Using stochastic optical reconstruction microscopy, we show that the drying process causes negligible distortion of structures and that less structural deformation could be achieved through simple buffer exchange to hexamethyldisilazane. Using DecoM, we visualize the nanoscale alterations in microtubules by microtubule-severing proteins that cannot be observed with diffraction-limited fluorescence microscopy. We then combine DecoM with expansion microscopy to enable sub-micron resolution BF microscopy imaging. We first show that silver-grown AuNPs strongly absorb white light, and the structures labeled with them are clearly visible on BF microscopy. We then show that the application of AuNPs and silver development must follow expansion to visualize the labeled proteins clearly with sub-micron resolution.
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Strong, Chemically Stable, and Enzymatically On-Demand Detachable Hydrogel Adhesion Using Protein Crosslink
Lee, Wonseok
;
Heo, Eunseok
;
Koo, Hye Been
, et al.
Macromol. Rapid Comm.,2023,44(4):2200750.
DOI:
10.1002/marc.202200750
PubMed ID:
36484110
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Abstract: Achieving strong adhesion between hydrogels and diverse materials is greatly significant for emerging technologies yet remains challenging. Existing methods using non-covalent bonds have limited pH and ion stability, while those using covalent bonds typically lack on-demand detachment capability, limiting their applications. In this study, a general strategy of covalent bond-based and detachable adhesion by incorporating amine-rich proteins in various hydrogels and inducing the interfacial crosslinking of the hydrogels using a protein-crosslinking agent is demonstrated. The protein crosslink offers topol. adhesion and can reach a strong adhesion energy of ≈750 J m-2. The chem. of the adhesion is characterized and that the inclusion of proteins inside the hydrogels does not alter the hydrogels' properties is shown. The adhesion remains intact after treating the adhered hydrogels with various pH solutions and ions, even at an elevated temperature The detachment is triggered by treating proteinase solution at the bonding front, causing the digestion of proteins, thus breaking up the interfacial crosslink network. In addition, that this approach can be used to adhere hydrogels to diverse dry surfaces, including glass, elastomers and plastics, is shown. The stable chem. of protein crosslinks opens the door for various applications in a wide range of chem. environments.
Keywords:
covalent adhesion ;
detachable adhesion ;
hydrogels ;
otein crosslinks
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Fabrication of Heterogeneous Chemical Patterns on Stretchable Hydrogels Using Single-Photon Lithography
Haeseong Im
;
Eunseok Heo
;
Dae-Hyeon Song
, et al.
Soft Matter,2022,18(23):4402-4413.
DOI:
10.1039/D2SM00253A
PubMed ID:
35635476
More
Abstract: Curved hydrogel surfaces bearing chemical patterns are highly desirable in various applications, including artificial blood vessels, wearable electronics, and soft robotics. However, previous studies on the fabrication of chemical patterns on hydrogels employed two-photon lithography, which is still not widely accessible to most laboratories. This work demonstrates a new patterning technique for fabricating curved hydrogels with chemical patterns on their surfaces without two-photon microscopy. In this work, we show that exposing hydrogels in fluorophore solutions to single photons via confocal microscopy enables the patterning of fluorophores on hydrogels. By applying this technique to highly stretchable hydrogels, we demonstrate three applications: (1) improving pattern resolution by fabricating patterns on stretched hydrogels and then returning the hydrogels to their initial, unstretched length; (2) modifying the local stretchability of hydrogels at a microscale resolution; and (3) fabricating perfusable microchannels with chemical patterns by winding chemically patterned hydrogels around a template, embedding the hydrogels in a second hydrogel, and then removing the template. The patterning method demonstrated in this work may facilitate a better mimicking of the physicochemical properties of organs in tissue engineering and may be used to make hydrogel robots with specific chemical functionalities.
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