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Microscopic structure of swollen hydrogels by scanning electron and light microscopies: artifacts and reality
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SYSNO ASEP 0523883 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název Microscopic structure of swollen hydrogels by scanning electron and light microscopies: artifacts and reality Tvůrce(i) Kaberova, Zhansaya (UMCH-V) RID
Karpushkin, E. (RU)
Nevoralová, Martina (UMCH-V) RID, ORCID
Vetrík, Miroslav (UMCH-V) RID, ORCID
Šlouf, Miroslav (UMCH-V) RID, ORCID
Dušková-Smrčková, Miroslava (UMCH-V) RIDČíslo článku 578 Zdroj.dok. Polymers. - : MDPI
Roč. 12, č. 3 (2020), s. 1-18Poč.str. 18 s. Jazyk dok. eng - angličtina Země vyd. CH - Švýcarsko Klíč. slova hydrogel ; PHEMA ; poly(2-hydroxyethyl methacrylate) Vědní obor RIV CD - Makromolekulární chemie Obor OECD Polymer science CEP GA17-08531S GA ČR - Grantová agentura ČR TE01020118 GA TA ČR - Technologická agentura ČR TN01000008 GA TA ČR - Technologická agentura ČR Způsob publikování Open access Institucionální podpora UMCH-V - RVO:61389013 UT WOS 000525952000077 EID SCOPUS 85082652432 DOI 10.3390/polym12030578 Anotace The exact knowledge of hydrogel microstructure, mainly its pore topology, is a key issue in hydrogel engineering. For visualization of the swollen hydrogels, the cryogenic or high vacuum scanning electron microscopies (cryo-SEM or HVSEM) are frequently used while the possibility of artifact-biased images is frequently underestimated. The major cause of artifacts is the formation of ice crystals upon freezing of the hydrated gel. Some porous hydrogels can be visualized with SEM without the danger of artifacts because the growing crystals are accommodated within already existing primary pores of the gel. In some non-porous hydrogels the secondary pores will also not be formed due to rigid network structure of gels that counteracts the crystal nucleation and growth. We have tested the limits of true reproduction of the hydrogel morphology imposed by the swelling degree and mechanical strength of gels by investigating a series of methacrylate hydrogels made by crosslinking polymerization of glycerol monomethacrylate and 2-hydroxyethyl methacrylate including their interpenetrating networks. The hydrogel morphology was studied using cryo-SEM, HVSEM, environmental scanning electron microscopy (ESEM), laser scanning confocal microscopy (LSCM) and classical wide-field light microscopy (LM). The cryo-SEM and HVSEM yielded artifact-free micrographs for limited range of non-porous hydrogels and for macroporous gels. A true non-porous structure was observed free of artifacts only for hydrogels exhibiting relatively low swelling and high elastic modulus above 0.5 MPa, whereas for highly swollen and/or mechanically weak hydrogels the cryo-SEM/HVSEM experiments resulted in secondary porosity. In this contribution we present several cases of severe artifact formation in PHEMA and PGMA hydrogels during their visualization by cryo-SEM and HVSEM. We also put forward empirical correlation between hydrogel morphological and mechanical parameters and the occurrence and intensity of artifacts Pracoviště Ústav makromolekulární chemie Kontakt Eva Čechová, cechova@imc.cas.cz ; Tel.: 296 809 358 Rok sběru 2021 Elektronická adresa https://www.mdpi.com/2073-4360/12/3/578
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