Polyacrylamide Network Research Articles

Flexible Triboelectric Nanogenerator Patch for Accelerated Wound Healing Through the Synergy of Electrostimulation and Photothermal Effect.

Physiological wound healing process can restore the functional and structural integrity of skin, but is often delayed due to external disturbance. The development of methods for promoting the repair process of skin wounds represents a highly desired and challenging goal. Here, a flexible, self-powered, and multifunctional triboelectric nanogenerator (TENG) wound patch (e-patch) is presented for accelerating wound healing through the synergy of electrostimulation and photothermal effect. To fabricate the triboelectric e-patch, a flexible and conductive hydrogel with a dual network of polyacrylamide (PAM) and polydopamine (PDA) is synthesized and doped with multi-walled carbon nanotubes (MCNTs). The hydrogel exhibits high conductivity, good stretchability, and high biocompatibility. The triboelectric e-patch assembled from the hydrogel can detect mechanical and electrical signals of human motions in a real-time manner. In a rodent model of full-thickness dorsal skin wound, the e-patch integrating self-driven electrostimulation and photothermal effect under the near-infrared light irradiation efficiently promotes wound repair and hair follicle regeneration through relieving inflammation, fastening collagen deposition, vascular regeneration, and epithelialization. It offers a promising way to accelerate wound healing.

Tissue adhesive hyaluronan-quercetin (Ago)@halloysite-fungal carboxymethyl chitosan nanocomposite hydrogels for wound dressing applications

This study investigates nanocomposite hydrogels reinforced with hyaluronan-quercetin‑silver nanoparticles intercalated halloysite clay (HAQ-Hal-Ag) for potential application as wound dressings. HAQ-Hal-Ag (at 1, 3, and 5 wt%) was incorporated into a fungal carboxymethyl chitosan (FC)/polyacrylamide (PAM) network (FC-PAM) using methylene bisacrylamide (MBA) as the crosslinker and ammonium persulfate (APS) as the initiator. Various physicochemical analyses were performed to characterize the resulting hydrogels. The compressive strength of the nanocomposite hydrogels exhibited a proportional increase with increasing HAQ-Hal-Ag content, reaching a remarkable 0.83 MPa for hydrogels containing 5 wt% HAQ-Hal-Ag. Additionally, the hydrogels displayed highly porous structures with excellent swelling capacity. Importantly, they exhibited exceptional antibacterial efficacy against Escherichia coli and Staphylococcus aureus. Furthermore, cytotoxicity assays revealed high cell viability and proliferation rates, confirming the biocompatibility of these hydrogels with human dermal fibroblasts. These findings suggest significant promise for the nanocomposite hydrogels as wound dressing materials due to their outstanding biocompatibility, impressive compressive strength, and potent antibacterial activity.

Self-Healing and Antifreezing/Antidrying Conductive Eutectohydrogel-Based Biosignal Monitoring Multisensors with Integrated Supercapacitor.

A novel self-healing and antifreezing/antidrying conductive eutectohydrogel, ideal for wearable multifunctional sensors and supercapacitors, is reported. Conductive eutectohydrogel with self-healing and facilely tunable mechanical performance is obtained by incorporation of trehalose and phytic acid as reversible cross-linkers into a polyacrylamide network, forming the dynamic hydrogen bonding and electrostatic interactions. Furthermore, combined use of deep eutectic solvent with water ensures the air stability as well as the antifreezing/antidrying characteristics. The synthesized eutectohydrogel exhibits a self-healing efficiency of 90.7% after 24 h at room temperature, Young's modulus of 140.9 kPa, and strain at break of 352.8%. With the eutectohydrogel as a versatile platform, self-healing strain and temperature sensors, electrocardiogram electrodes, and supercapacitor are fabricated, recovering the device performance after self-healing from complete bisection and exhibiting stable performance over a wide temperature range from -20 to 50°C. With a vertically integrated patch device of supercapacitor and strain sensor attached onto skin, various body movements are successfully detected using the energy stored in the supercapacitor, without performance degradation even after self-healing from complete bisection of the full patch device. This work demonstrates high potential application of the synthesized eutectohydrogel to flexible wearable devices featuring durability and longevity.

Mechanoresponsive self‐powered piezoelectric energy‐generating composite hydrogels based on carbon nanotube‐reinforced fungal‐carboxymethyl chitosan‐bacterial cellulose nanofibers for wearable electronics

AbstractDeveloping conductive hydrogels with both enhanced mechanical properties and superior sensing capabilities for wearable, flexible electronics remains challenging. Here, we developed mechanoresponsive self‐powered piezoelectric energy‐generating composite hydrogels. These hydrogels were prepared by blending fungal‐derived carboxymethyl chitosan (FC), carboxylate‐bacterial cellulose nanofibers (CBC‐NFs), and carbon nanotubes (CNTs) within a covalently crosslinked polyacrylamide (PAM) network (CNT‐FBCNF). The resulting hydrogels showed remarkable mechanical properties due to the molecular interactions between polymer chains. The hydrogels showed a self‐recoverable property and high stability under compressive mechanical force at 40% of strain (2000 cycles). The maximum compressive load (N) of 27.8 N was obtained for the optimized hydrogel, CNT‐FBCNF (1% CNT content). This hydrogel exhibited a good conductivity of 1.3 S/m, which was attributed to the homogeneous dispersion of CNTs within the hydrogel matrix and sufficient biocompatibility with skin fibroblasts. The hydrogel also exhibited impressive performance as a strain sensor, boasting a wide strain range (10–40%), excellent stability, and repeatability. Furthermore, strategic cutting and assembly of the hydrogel generated a flexible strain sensor capable of accurately monitoring finger and thumb pressure in real‐time. This study will significantly accelerate the development of hydrogel‐based sensors within the rapidly advancing field of wearable soft electronics.Highlights CNT‐reinforced composite hydrogel was developed The optimized hydrogel showed good electrical conductivity (1.3 S/m) The optimized hydrogel showed good self‐recovery properties The optimized hydrogel exhibited impressive strain‐sensing capability between 10% and 40% strain

3D-Printed Flexible Polyacrylamide/Alginate Gel Polymer Electrolyte for Zinc-Ion Batteries

Flexible and wearable electronics are increasingly popular and utilized in various forms. Batteries have become essential as an energy source for wearable electronics. To meet demands of such electronics, these batteries must remain flexible, lightweight, possess good electrochemical performance, customizable shape, and ensure safety. Zinc-ion batteries (ZIBs) have emerged as a promising energy source for these applications. However, ZIBs encounter challenges due to the lack of flexible electrolytes. Polyacrylamide (PAM) is a polymer widely used as gel polymer electrolytes (GPEs) owing to its versatile electrical conductivity and excellent flexibility. However, PAM alone lacks the mechanical strength required to support flexible and wearable electronics adequately. To address this limitation, alginate (Alg), a polysaccharide with good compatibility with PAM, is incorporated in varying concentrations (0-3 %wt.) to form interpenetrating networks (IPN) hydrogels, with a chemical network of PAM and a physical network of alginate to enhance the overall mechanical properties. Following this, the 3D-printed PAM/Alg hydrogels are immerged in a 2M ZnSO4 electrolyte to create PAM/Alg gel polymer electrolytes (PAM/Alg-GPEs). This process significantly improves the mechanical properties of PAM/Alg-GPEs. Subsequently, the ionic conductivity of these 3D-printed PAM/Alg-GPEs is evaluated using electrochemical impedance spectroscopy (EIS). The results demonstrate that PAM/Alg-GPEs exhibit the desired flexibility along with sufficient electrochemical performance, making them promising candidates for use as wearable electrolytes in zinc-ion batteries.

Enhancing performance of Si/C composite anode in high energy density lithium-ion batteries with CMC-CPAM-SBR binder

Abstract The utilization of polymeric binders is indispensable in the implementation of silicon/carbon anode materials in high-energy-density lithium-ion batteries (LIBs). This necessity arises from their pivotal function in upholding structural integrity. However, current water-based binders solely focus on binder adhesion, neglecting the crucial interaction with the carbon material. In this work, a composite binder (CMC-CPAM-SBR) was constructed by combining Styrene Butadiene Rubber (SBR) with cationic polyacrylamide (CPAM) network binder with self-healing carboxymethyl cellulose (CMC). This innovative binder formulation was designed to enhance the performance of Si@C/graphite composite anodes. A capacity retention rate of 92.86% was achieved after 100 cycles, which represents the improvement over the performance of electrodes utilizing the CMC-CPAM binder, which only retained a capacity of 84.53% after the same number of cycles. A full battery with a capacity of 1992.8 mAh was designed, and the battery capacity remained at 80.6% of its capacity after completing 500 cycles. This research presents an effective technique for manufacturing high-performance anode materials.

Stretchable, Self-Healing, and Bioactive Hydrogel with High-Functionality N,N'-bis(acryloyl)cystamine Dynamically Bonded Ag@polydopamine Crosslinkers for Wearable Sensors.

Hydrogels present attractive opportunities as flexible sensors due to their soft nature and tunable physicochemical properties. Despite significant advances, practical application of hydrogel-based sensor is limited by the lack of general routes to fabricate materials with combination of mechanical, conductive, and biological properties. Here, a multi-functional hydrogel sensor is reported by in situ polymerizing of acrylamide (AM) with N,N'-bis(acryloyl)cystamine (BA) dynamic crosslinked silver-modified polydopamine (PDA) nanoparticles, namely PAM/BA-Ag@PDA. Compared with traditional polyacrylamide (PAM) hydrogel, the BA-Ag@PDA nanoparticles provide both high-functionality crosslinks and multiple interactions within PAM networks, thereby endowing the optimized PAM/BA-Ag@PDA hydrogel with significantly enhanced tensile/compressive strength (349.80kPa at 383.57% tensile strain, 263.08kPa at 90% compressive strain), lower hysteresis (5.2%), improved conductivity (2.51 S m-1) and excellent near-infrared (NIR) light-triggered self-healing ability. As a strain sensor, the PAM/BA-Ag@PDAhydrogel shows a good sensitivity (gauge factor of 1.86), rapid response time (138ms), and high stability. Owing to abundant reactive groups in PDA, the PAM/BA-Ag@PDA hydrogel exhibits inherent tissue adhesiveness and antioxidant, along with a synergistic antibacterial effect by PDA and Ag. Toward practical applications, the PAM/BA-Ag@PDA hydrogel can conformally adhere to skin and monitor subtle activities and large-scale movements with excellent reliability, demonstrating its promising applications as wearable sensors for healthcare.

Wearable photonic crystal double network hydrogel sensor based on structural color analysis

Abstract This paper introduces a high-toughness photonic crystal (PhCs) dual-network hydrogel sensor designed for mechanical sensing, which enables quantitative analysis of structural color using the HSB color space. The hydrogel achieves a maximum tensile strain of 250% under a tensile stress of 3.5 MPa, thanks to its dual-network structure comprising a covalently cross-linked polyacrylamide (PAM) network and an ionically cross-linked sodium alginate (SA) network. At an 80% tensile strain, the PAM-SA photonic crystal hydrogel displays a blue shift in the bandgap wavelength of over 130 nm and demonstrates a sensitivity of 1.69 nm/%. The analysis of the force-induced color change in the PAM-SA photonic crystal hydrogel utilized both RGB and HSB color spaces. In the HSB color space, the hue component (H) exhibited a strong linear correlation with strain (R2>0.95), indicating the feasibility of quantitative structural color analysis using HSB. As a wearable sensor, the PAM-SA photonic crystal hydrogel precisely detects human motion via bandgap displacement (R2=0.989) and structural color change (R2=0.978). The PAM-SA PhCs hydrogel, featuring easily accessible color information and high sensitivity, has broad potential applications in wearable devices and mechanical sensors.

Advanced hydrogel electrolyte with enhanced interfacial adhesion and low-temperature resistant for flexible zinc-ion batteries

Flexible zinc-ion batteries (ZIBs) have great potential in wearable devices due to their excellent mechanical properties, safety and high energy density. However, the poor adhesion of the electrodes in bending, folding and low-temperature environments remains a challenge. In this study, we developed a dual-network hydrogel electrolyte (C-PAM@TA) by incorporating tannic acid (TA) into a cross-linked polyacrylamide (PAM) network. The C-PAM@TA hydrogel electrolyte exhibits strong interfacial adhesion, high ion conductivity, and low-temperature frost resistance. Through experimental and theoretical analyses, we demonstrate that TA helps regulate anion/cation transport channels, weakens the solvation of zinc ions and enables stable and uniform plating/stripping behavior of the zinc metal anode. As a result, the Zn//Zn symmetric cell employing the C-PAM@TA hydrogel electrolyte exhibits outstanding cycling stability (2000 h) at 0.5 mA cm−2. Furthermore, the assembled Zn//C-PAM@TA//fcc@PANI flexible ZIBs can undergo 7000 cycle stability tests, withstand 4500 bending tests and operate normally in a low-temperature environment of −18 ℃. This study successfully develops high-performance, low-temperature resistant flexible ZIBs, providing valuable insights for the design of multifunctional flexible energy storage and wearable electronic devices.

Robust, superabsorbent and antibacterial polysaccharide-based hybrid-network hydrogels for wound repair

Hydrogel dressings with multiple functions are ideal options for wound repair. This study developed hydrogel dressings by interpenetrating the physically crosslinked xanthan gum (XG)/carboxylated chitosan (CCS) network and the chemically crosslinked polyacrylamide (PAAm) network via a one-pot method. The XG-CCS/PAAm hydrogels were found to display tunable mechanical properties, due to the formation of strong network structure. The hydrogels exhibited the strongest tensile strength of 0.6 MPa at an XG/CCS ratio of 40/60, while the largest compressive strength of 4.5 MPa is achieved at an XG/CCS ratio of 60/40. Moreover, the hydrogel with an XG/CCS ratio of 60/40 exhibited desirable adhesion strength on porcine skin, which was 3.7 kPa. It also had a swelling ratio, as high as 1200 %. After loading with cephalexin, the XG-CCS/PAAm hydrogels can deliver the antibacterial drugs following a first-order kinetic. As a result, both E. coli and S. aureus can be completely inactivated by the cefalexin-loaded hydrogels after 12 h. Furthermore, the XG-CCS/PAAm hydrogels were found to exhibit excellent biocompatibility as well as effective wound healing ability, as proven by the in vitro and in vivo tests. In this regard, XG-CCS/PAAm hydrogels can act as promising multifunctional wound dressings.

Tough, self-healing, adhesive double network conductive hydrogel based on gelatin-polyacrylamide covalently bridged by oxidized sodium alginate for durable wearable sensors

Pursuing high-performance conductive hydrogels is still hot topic in development of advanced flexible wearable devices. Herein, a tough, self-healing, adhesive double network (DN) conductive hydrogel (named as OSA-(Gelatin/PAM)-Ca, O-(G/P)-Ca) was prepared by bridging gelatin and polyacrylamide network with functionalized polysaccharide (oxidized sodium alginate, OSA) through Schiff base reaction. Thanks to the presence of multiple interactions (Schiff base bond, hydrogen bond, and metal coordination) within the network, the prepared hydrogel showed outstanding mechanical properties (tensile strain of 2800 % and stress of 630 kPa), high conductivity (0.72 S/m), repeatable adhesion performance and excellent self-healing ability (83.6 %/79.0 % of the original tensile strain/stress after self-healing). Moreover, the hydrogel-based sensor exhibited high strain sensitivity (GF = 3.66) and fast response time (<0.5 s), which can be used to monitor a wide range of human physiological signals. Based on this, excellent compression sensitivity (GF = 0.41 kPa−1 in the range of 90–120 kPa), a three-dimensional (3D) array of flexible sensor was designed to monitor the intensity of pressure and spatial force distribution. In addition, a gel-based wearable sensor was accurately classified and recognized ten types of gestures, achieving an accuracy rate of >96.33 % both before and after self-healing under three machine learning models (the decision tree, SVM, and KNN). This paper provides a simple method to prepare tough and self-healing conductive hydrogel as flexible multifunctional sensor devices for versatile applications in fields such as healthcare monitoring, human-computer interaction, and artificial intelligence.

Phase transition in polymer hydrogels investigated by swelling, DSC, FTIR and NMR

AbstractThe swelling and thermal behavior of single (SN) and double network (DN) hydrogels containing polyacrylamide (PAAm) and temperature sensitive poly(N, N-diethylacrylamide) (PNNDEAAm) were investigated by gravimetry and differential scanning calorimetry (DSC). Changes of the hydration of carbonyl groups and mobility of polymer network chains in the hydrogels with temperature were studied by Fourier-transformed infrared and proton nuclear magnetic resonance (1H NMR) spectroscopy. The enthalpy of dissociation of the hydrophobic interaction, minimum and maximum numbers of water molecules per monomer unit in PNNDEAAm SN hydrogel involved in the hydrophobic hydration were determined by DSC. The volume phase transition accompanied by expulsion/uptake of water and heat absorption/release in heating/cooling was exhibited by all DN hydrogels containing PNNDEAAm. In these hydrogels, above the phase transition temperature, the population of hydrated carbonyls is enriched with the free and single hydrated ones in the same way as in the aqueous solution of linear PNNDEAAm and mobility of the PNNDEAAm chains is strongly reduced. Presence of the PAAm network does not influence the phase transition temperature but strongly reduces the enthalpy of the phase transition, promotes higher degrees of hydration of carbonyls, and increases mobility of the PNNDEAAm chains in the mixed hydrogels above the phase transition temperature.

A Cellulose Reinforced Polyacrylamide/Polyvinyl Alcohol Dual Network Hydrogel for Flexible Sensors

AbstractIn this paper, polyacrylamide (PAM) was used as the main matrix material to form the first layer network structure, and polyvinyl alcohol (PVA) was used as the secondary matrix material to form the second layer network structure. The hydrogels were prepared by free radical in‐situ polymerization and physical cross‐linking. This hydrogel was characterized not only by its semi‐interpenetrating network structure, in which cellulose nanocrystals (CNC) penetrate through the polyacrylamide network but also by the physically and chemically cross‐linked hybrid PAM/PVA double network. The structure and appearance of the hydrogels were characterized by scanning electron microscope and Fourier transform infrared spectrometer, and a series of tests were carried out to detect their mechanical properties, electrical properties and sensing properties. The results show that the hydrogel has good mechanical properties (the elongation at break can reach 600 % and the stress at break can reach 0.16 MPa), and the hydrogel also has good sensing and electrical properties. The addition of organic solvents makes the hydrogels have excellent antifreeze and water retention properties and also have excellent swelling properties. Therefore, the PAM/PVA/CNC dual network interpenetrating composite hydrogel has potential application value in the field of flexible sensors.

Environment-tolerant gelatin based ionic conductive organohydrogel for flexible sensor

Flexible wearable devices based on hydrogels have attracted more and more attention, however, the preparation of hydrogels with high toughness, conductivity and anti-freezing and anti-drying is still a challenge. In this study, a chemical-physical cross-linked double network conductive organohydrogel was designed by incorporating gelatin and Lithium chloride (LiCl) into polyacrylamide (AM) network with water-glycerol binary solvent. The results displayed that the organohydrogel exhibited high toughness, high stretchability, anti-freezing and anti-drying capability. With the addition of glycerol and LiCl, the organohydrogel has shown good conductivity in wide ranges of temperature. Moreover, the organohydrogel could be used as a strain sensor for the detection of various human body motions. Meanwhile, it was found that the introduction of LiCl enhanced the strain sensing performance, the stability and working temperature range. The sensors exhibited a high thermal sensitivity (5.72 % /℃), broad temperature detection range (0–65℃). These outstanding advantages indicated that the organohydrogels have potential application as strain and temperature sensors.

A short linear glucan nanocomposite hydrogel formed by in situ self-assembly with highly elastic, fatigue-resistant and self-recovery

Polyacrylamide (PAM) hydrogels are widely used in wide-ranging applications in biology, medicine, pharmaceuticals and environmental sectors. However, achieving the requisite mechanical properties, fatigue resistance, self-recovery, biocompatibility, and biodegradability remains a challenge. Herein, we present a facile method to construct a nanocomposite hydrogel by integrating short linear glucan (SLG), obtained by debranching waxy corn starch, into a PAM network through self-assembly. The resulting composite hydrogel with 10 % SLG content exhibited satisfactory stretchability (withstanding over 1200 % strain), along with maximum compressive and shear strengths of about 490 kPa and 39 kPa at 90 % deformation, respectively. The hydrogel demonstrated remarkable resilience and could endure repeated compression and stretching. Notably, the nanocomposite hydrogel with 10 % SLG content exhibited full stress recovery at 90 % compression deformation after 20 s, without requiring specific environmental conditions, achieving an energy dissipation recovery rate of 98 %. Meanwhile, these hydrogels exhibited strong adhesion to various soft and hard substrates, including skin, glasses and metals. Furthermore, they maintain solid integrity at both 37 °C and 50 °C after swelling equilibrium, unlike traditional PAM hydrogels, which exhibited softening under similar conditions. We hope that this PAM-SLG hydrogel will open up new avenues for the development of multifunctional electronic devices, offering enhanced performance and versatility.

Lean-water hydrogel electrolyte with improved ion conductivity for dendrite-free zinc-Ion batteries

Although rechargeable aqueous zinc-ion batteries (ZIBs) are regarded as promising energy storage devices, the uncontrollable Zn dendrite and undesirable side reactions severely limit their practical applications. Herein, an anionic hydrogel electrolyte PAM/SA with 3D porous structures is developed by integrating sodium alginate (SA) and polyacrylamide (PAM) networks for highly reversible Zn plating/stripping. Mechanically enhanced and lean-water PAM/SA hydrogel with anionic chains for constructing ionic channels and molecular lubrication films, which facilitate Zn2+ migration for a high ionic conductivity (5.4 S m−1) and Zn2+ transference number (0.86) even under lean-water conditions (about 60%). Based on the experimental and theoretical analysis, the SA chain with strong coordination ability endows PAM/SA with improved desolvation kinetics and the ability to regulate the electric field intensity at the electrode/electrolyte interface, which is beneficial for suppressing side reactions and facilitating directional Zn deposition. Subsequently, the symmetric Zn//Zn cell based on PAM/SA hydrogel electrolyte delivers stable cycles for over 1800 h. The assembled Zn//V2O5 battery based on PAM/SA reveals a high specific capacity and a long cycle life. This work provides a new insight for developing hydrogel electrolytes with high ionic conductivity and lean-water properties toward stable Zn anode

Carboxylic bacterial cellulose fiber-based hydrogel electrolyte with imidazole-type ionic liquid for dendrite-free zinc metal batteries

Aqueous zinc metal batteries are regarded as the most promising energy storage system due to their advantages of high safety, low cost, and high theoretical capacity. However, the growth of dendrites and the occurrence of side reactions hinder the development of zinc metal batteries. Despite previous attempts to design advanced hydrogel electrolytes, achieving high mechanical performance and ionic conductivity of hydrogel electrolytes has remained challenging. In this work, a hydrogel electrolyte with an ionic crosslinked network is prepared by carboxylic bacterial cellulose fiber and imidazole-type ionic liquid, following by a covalent network of polyacrylamide. The hydrogel electrolyte possesses a superior ionic conductivity of 43.76 mS cm−1, leading to a Zn2+ migration number of 0.45, and high mechanical performance with an elastic modulus of 3.48 GPa and an elongation at breaking of 38.36%. More importantly, under the anion-coordination effect of the carboxyl group in bacterial cellulose and [BF4]− in imidazole-type ionic liquid, the solvation sheath of hydrated Zn2+ ions and the nucleation overpotential of Zn plating are regulated. The results of cycled testing show that the growth of zinc dendrites is effectively inhibited and the generation of irreversible by-products is reduced. With the carboxylic bacterial cellulose-based hydrogel electrolyte, the Zn||Zn symmetric batteries offer good cyclability as well as Zn||Ti batteries.

An injectable polyacrylamide/chitosan-based hydrogel with highly adhesive, stretchable and electroconductive properties loaded with irbesartan for treatment of myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury (MIRI) significantly contributes to the high incidence of complications and mortality associated with acute myocardial infarction. Recently, injectable electroconductive hydrogels (IECHs) have emerged as promising tools for replicating the mechanical, electroconductive, and physiological characteristics of cardiac tissue. Herein, we aimed to develop a novel IECH by incorporating irbesartan as a drug delivery system (DDS) for cardiac repair. Our approach involved merging a conductive poly-thiophene derivative (PEDOT: PSS) with an injectable dual-network adhesive hydrogel (DNAH) comprising a catechol-branched polyacrylamide network and a chitosan-hyaluronic acid covalent network. The resulting P-DNAH hydrogel, benefitting from a high conducting polymer content, a chemically crosslinked network, a robust dissipative matrix, and dynamic oxidation of catechol to quinone exhibited superior mechanical strength, desirable conductivity, and robust wet-adhesiveness. In vitro experiments with the P-DNAH hydrogel carrying irbesartan (P-DNAH-I) demonstrated excellent biocompatibility by cck-8 kit on H9C2 cells and a rapid initial release of irbesartan. Upon injection into the infarcted hearts of MIRI mouse models, the P-DNAH-I hydrogel effectively inhibited the inflammatory response and reduced the infarct size. In conclusion, our results suggest that the P-DNAH hydrogel, possessing suitable mechanical properties and electroconductivity, serves as an ideal IECH for DDS, delivering irbesartan to promote heart repair.

Viscoelastic polyacrylamide MR elastography phantoms with tunable damping ratio independent of shear stiffness

Physiologically modeled test samples with known properties and characteristics, or phantoms, are essential for developing sensitive, repeatable, and accurate quantitative MRI techniques. Magnetic resonance elastography (MRE) is one such technique used to estimate tissue mechanical properties, and it is advantageous to use phantoms with independently tunable mechanical properties to benchmark the accuracy of MRE methods. Phantoms with tunable shear stiffness are commonly used for MRE, but tuning the viscosity or damping ratio has proven to be difficult. A promising candidate for MRE phantoms with tunable damping ratio is polyacrylamide (PAA). While pure PAA has very low attenuation, viscoelastic hydrogels have been made by entrapping linear polyacrylamide strands (LPAA) within the PAA network. In this study, we evaluate the use of LPAA/PAA gels as physiologically accurate phantoms with tunable damping ratio, independent of shear stiffness, via MRE. Phantoms were made with 15.3 wt% PAA while the LPAA concentration ranged from 4.5 wt% to 8.0 wt%. MRE was performed at 9.4 T with 400 Hz vibration on all phantoms revealing a strong, positive correlation between damping ratio and LPAA content (p < 0.001). There was no significant correlation between shear stiffness and LPAA content, confirming a constant PAA concentration yielded constant shear stiffness. Rheometry at 10 Hz was performed to verify the damping ratio of the phantoms. Nearly identical slopes for damping ratio versus LPAA content were found from both MRE and rheometry (0.0073 and 0.0075 respectively). Ultimately, this study validates the adaptation of polyacrylamide gels into physiologically-relevant MRE phantoms to enable testing of MRE estimates of damping ratio.

High‐Adhesion, Weather Resistance, Reusable PAM/Gly/Gel/TA/Fe3+ Biopolymer Dual‐Network Conductive Hydrogel for Flexible Bioelectrode

AbstractConductive hydrogel is considered a promising wearable sensor material. Developing flexible conductive hydrogel sensors with stretchability, adhesion, and stability remains challenging. In this study, a transparent, self‐adhesive, antifreeze, anti‐UV, stretchable, conductive, and reusable hydrogel with polyacrylamide/glycerol/gelatin/tannic acid/Fe3+ (PGGT‐Fe3+) structure is successfully constructed through a simple one‐pot polymerization method. The PGGT‐Fe3+ hydrogel is composed of dual networks of polyacrylamide and gelatin for organic cross‐linking, using water/glycerol as the dispersion medium, and incorporates a viscous substance: tannic acid, and a conductive substance: metal ions (Fe3+). Due to the introduction of the abundant amino, carboxylic acid, and hydroxyl functional groups on gelatin and tannic acid, the PGGT‐Fe3+ hydrogel exhibits excellent and repeatable adhesion capabilities on various surfaces (including glass, metal, plastic, and pigskin) with maximum adhesion strength of 98 kPa when attached to pigskin. Furthermore, based on the stable conductive network and high conductivity, the hydrogel not only exhibits strain sensitivity, fast response, and stability but also can stably collect epidermal bio signals. In conclusion, this work provides a new approach to the design and development of next‐generation multifunctional conductive hydrogels and opens up vast possibilities for their applications in the flexible electronics field.