Tissue-Adhesive and Biocompatible Zein-Polyaniline-Based Hydrogels for Mechanoresponsive Energy-Harvesting Applications

Flexible, biocompatible, and adhesive materials are vital for wearable strain sensors in bioelectronics. This study presents zein-polyaniline (ZPANI) hydrogels with mechanoresponsive energy-harvesting properties. SEM revealed a sheet-like fibrous morphology, enhancing adhesion. Incorporating 0.5 wt%...

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Main Authors: Maduru Suneetha, Seainn Bang, Sarah A. Alshehri, Sung Soo Han
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Gels
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Online Access:https://www.mdpi.com/2310-2861/11/5/307
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author Maduru Suneetha
Seainn Bang
Sarah A. Alshehri
Sung Soo Han
author_facet Maduru Suneetha
Seainn Bang
Sarah A. Alshehri
Sung Soo Han
author_sort Maduru Suneetha
collection DOAJ
description Flexible, biocompatible, and adhesive materials are vital for wearable strain sensors in bioelectronics. This study presents zein-polyaniline (ZPANI) hydrogels with mechanoresponsive energy-harvesting properties. SEM revealed a sheet-like fibrous morphology, enhancing adhesion. Incorporating 0.5 wt% polyaniline (PANI) introduced nanostructured aggregates, while higher PANI concentrations (3–5 wt%) formed intertwined fibrous networks, improving the mechanical integrity, surface area, and conductivity. PANI enhanced electrical conductivity, and the hydrogels displayed excellent swelling behavior, ensuring flexibility and strong tissue adhesion. Biocompatibility was validated through fibroblast cell culture assays, and the adhesive properties were tested on substrates, such as porcine skin, steel, and aluminum, demonstrating versatile adhesion. The adhesion strength of hydrogels to porcine skin was greatly enhanced with an increasing amount of PANI. The maximum adhesion strength was found to be 30.1 ± 2.1 kPa for ZPANI-5.0. Mechanical testing showed a trade-off between strength and conductivity. The tensile strength decreased from 13.4 kPa (ZPANI-0) to 7.1 kPa (ZPANI-5.0), and the compressive strength declined from 18.5 kPa to 1.6 kPa, indicating increased brittleness. A rheological analysis revealed enhanced strain tolerance (>500% strain) with an increasing PANI content. The storage modulus (G′) remained stable up to 100% strain in PANI-free hydrogels but collapsed beyond 450% strain, while PANI-containing hydrogels exhibited improved viscoelasticity. Mechanical testing showed robust voltage output signals under compression within a 20 s response time. Despite the reduced mechanical strength, energy-harvesting tests showed a surface power density of 0.12 nW cm<sup>−2</sup>, charge storage of 0.71 nJ, and a surface energy density of 1.4 pWh cm<sup>−2</sup>. The synergy of the piezoelectric response, bioadhesion, and tunable viscoelasticity establishes ZPANI hydrogels as promising candidates for wearable sensors and energy-harvesting applications. Optimizing the PANI content is crucial for balancing mechanical stability, adhesion, and electrical performance, ensuring long-term bioelectronic functionality.
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spelling doaj-art-d5df243213b84fecb7e10c10a0339d8d2025-08-20T03:14:41ZengMDPI AGGels2310-28612025-04-0111530710.3390/gels11050307Tissue-Adhesive and Biocompatible Zein-Polyaniline-Based Hydrogels for Mechanoresponsive Energy-Harvesting ApplicationsMaduru Suneetha0Seainn Bang1Sarah A. Alshehri2Sung Soo Han3School of Chemical Engineering, Yeungnam University, 280 Daehak-Ro, Gyeongsan 38541, Gyeongbuk, Republic of KoreaSchool of Chemical Engineering, Yeungnam University, 280 Daehak-Ro, Gyeongsan 38541, Gyeongbuk, Republic of KoreaDepartment of Chemistry, College of Science, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi ArabiaSchool of Chemical Engineering, Yeungnam University, 280 Daehak-Ro, Gyeongsan 38541, Gyeongbuk, Republic of KoreaFlexible, biocompatible, and adhesive materials are vital for wearable strain sensors in bioelectronics. This study presents zein-polyaniline (ZPANI) hydrogels with mechanoresponsive energy-harvesting properties. SEM revealed a sheet-like fibrous morphology, enhancing adhesion. Incorporating 0.5 wt% polyaniline (PANI) introduced nanostructured aggregates, while higher PANI concentrations (3–5 wt%) formed intertwined fibrous networks, improving the mechanical integrity, surface area, and conductivity. PANI enhanced electrical conductivity, and the hydrogels displayed excellent swelling behavior, ensuring flexibility and strong tissue adhesion. Biocompatibility was validated through fibroblast cell culture assays, and the adhesive properties were tested on substrates, such as porcine skin, steel, and aluminum, demonstrating versatile adhesion. The adhesion strength of hydrogels to porcine skin was greatly enhanced with an increasing amount of PANI. The maximum adhesion strength was found to be 30.1 ± 2.1 kPa for ZPANI-5.0. Mechanical testing showed a trade-off between strength and conductivity. The tensile strength decreased from 13.4 kPa (ZPANI-0) to 7.1 kPa (ZPANI-5.0), and the compressive strength declined from 18.5 kPa to 1.6 kPa, indicating increased brittleness. A rheological analysis revealed enhanced strain tolerance (>500% strain) with an increasing PANI content. The storage modulus (G′) remained stable up to 100% strain in PANI-free hydrogels but collapsed beyond 450% strain, while PANI-containing hydrogels exhibited improved viscoelasticity. Mechanical testing showed robust voltage output signals under compression within a 20 s response time. Despite the reduced mechanical strength, energy-harvesting tests showed a surface power density of 0.12 nW cm<sup>−2</sup>, charge storage of 0.71 nJ, and a surface energy density of 1.4 pWh cm<sup>−2</sup>. The synergy of the piezoelectric response, bioadhesion, and tunable viscoelasticity establishes ZPANI hydrogels as promising candidates for wearable sensors and energy-harvesting applications. Optimizing the PANI content is crucial for balancing mechanical stability, adhesion, and electrical performance, ensuring long-term bioelectronic functionality.https://www.mdpi.com/2310-2861/11/5/307tissue-adhesive hydrogelszein-polyanilinemechanoresponsive energy harvestingwearable strain sensors
spellingShingle Maduru Suneetha
Seainn Bang
Sarah A. Alshehri
Sung Soo Han
Tissue-Adhesive and Biocompatible Zein-Polyaniline-Based Hydrogels for Mechanoresponsive Energy-Harvesting Applications
Gels
tissue-adhesive hydrogels
zein-polyaniline
mechanoresponsive energy harvesting
wearable strain sensors
title Tissue-Adhesive and Biocompatible Zein-Polyaniline-Based Hydrogels for Mechanoresponsive Energy-Harvesting Applications
title_full Tissue-Adhesive and Biocompatible Zein-Polyaniline-Based Hydrogels for Mechanoresponsive Energy-Harvesting Applications
title_fullStr Tissue-Adhesive and Biocompatible Zein-Polyaniline-Based Hydrogels for Mechanoresponsive Energy-Harvesting Applications
title_full_unstemmed Tissue-Adhesive and Biocompatible Zein-Polyaniline-Based Hydrogels for Mechanoresponsive Energy-Harvesting Applications
title_short Tissue-Adhesive and Biocompatible Zein-Polyaniline-Based Hydrogels for Mechanoresponsive Energy-Harvesting Applications
title_sort tissue adhesive and biocompatible zein polyaniline based hydrogels for mechanoresponsive energy harvesting applications
topic tissue-adhesive hydrogels
zein-polyaniline
mechanoresponsive energy harvesting
wearable strain sensors
url https://www.mdpi.com/2310-2861/11/5/307
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AT seainnbang tissueadhesiveandbiocompatiblezeinpolyanilinebasedhydrogelsformechanoresponsiveenergyharvestingapplications
AT sarahaalshehri tissueadhesiveandbiocompatiblezeinpolyanilinebasedhydrogelsformechanoresponsiveenergyharvestingapplications
AT sungsoohan tissueadhesiveandbiocompatiblezeinpolyanilinebasedhydrogelsformechanoresponsiveenergyharvestingapplications