Mechanical Properties Of Hydrogels Research Articles

Flexible Strain-Sensitive Sensors Assembled from Mussel-inspired Hydrogel with Tunable Mechanical Properties and Wide Temperature Tolerance in Multiple Application Scenarios.

Conductive hydrogels, exhibiting wide applications in electronic skins and soft wearable sensors, often require maturely regulating of the hydrogel mechanical properties to meet specific demands and work for a long-term or under extreme environment. However, in situ regulation of the mechanical properties of hydrogels is still a challenge, and regular conductive hydrogels will inevitably freeze at subzero temperature and easily dehydrate, which leads to a short service life. Herein, a novel adhesive hydrogel (PAA-Dopa-Zr4+) capable of strain sensing is proposed with antifreezing, nondrying, strong surface adhesion, and tunable mechanical properties. 3,4-Dihydroxyphenyl-l-alanine (l-Dopa)-grafted poly(acrylic acid) (PAA) and Zr4+ ion are introduced into the hydrogel, which broadly alters the mechanical properties via tuning the in situ aggregation state of polymer chains by ions based on the complexation effect. The catechol groups of l-Dopa and viscous glucose endow the hydrogel with high adhesiveness for skin and device interface (including humid and dry environments) and exhibit an outstanding temperature tolerance under extreme wide temperature spectrum (-35 to 65 °C) or long-lasting moisture retention (60 days). Furthermore, this PAA-Dopa-Zr4+ can be assembled as a flexible strain-sensitive sensor to detect human motions based on specific mechanical properties requirements. This work, enabling superior adhesive and temperature tolerance performance and broad mechanical tenability, presents a new paradigm for numerous applications to wearable sensing and personalized healthcare monitoring.

Coenzyme a-responsive hydrogel sensor for wireless monitoring and treatment of osteoarthritis

A coenzyme A (CoA-SH)-responsive electronic hydrogel sensor that can relieve osteoarthritis based on carbonized polydopamine-integrated disulfide bonds-contained polymer dots (cPDA@PDA hydrogel) is conceived in this study. The cleavage of disulfide bonds occurred due to the accumulation of CoA-SH, controlling the release of carbonized polydopamine (cPDA) from the integrated polymer dots (PD). The hydrogel mechanical properties are altered, increasing the maximum stretching from 199.7 % to 352.9 % after 12 h and the shift in the surface morphology. The exposure to CoA-SH controls the release of the cPDA, decreasing the electronic resistivity from 147.1 kΩ to 56.99 kΩ after 12 h. In vitro analysis using the articular chondrocytes of wild type (WT), Nudt7-/-, and Acot12-/- shows a sensitivity toward CoA-SH, which is depicted by the decrease in electronic resistance after treatment. In vivo analysis shows a resistance of 131.1 kΩ for the Nudt7-/- mice, which is lower than the resistance of the NUDT7-restored mice (225.1 kΩ). Additionally, cartilage degradation could be prevented for mice-treated PD-containing hydrogel, showing tibia thickness of 111.5 μm compared to that without PD hydrogel (74.84 μm). This result indicates that the cPDA@PD hydrogel can diminish the accumulation of CoA-SH and facilitate the treatment of osteoarthritis.

Multi-functional nanocomposite hydrogels based on assembled catechin-modified TiO2 nanoparticle crosslinker for efficient dye removal from wastewater

The removal of contaminants from wastewater is a crucial step towards achieving sustainable development. Nanocomposite hydrogels have emerged as effective adsorbents; however, their limited elasticity, low light transmission, and insufficient self-healing properties hinder their practical applications. Here, we present durable and self-repairing nanocomposite hydrogels produced by free radical polymerization using an assembled structure of TiO2 and catechin, which acts as a crosslinking agent. This assembly enhances the hydrogel's mechanical properties and provides UV shielding and antioxidant features. This hydrogel, with its well-dispersed TiO2, can be activated by UV light to effectively eliminate heavy metal ions and degrade dye molecules from wastewater. These exceptional qualities demonstrate that the nanocomposite hydrogel based on the TiO2@catechin assembly structure has significant potential for advancing the field of wastewater treatment.

Synthesis of Silanized Bioactive Glass/Gelatin Methacrylate (GelMA/Si-BG) composite hydrogel for Bone Tissue Engineering Application

Bioactive glass (BG) has been widely employed in the field of bone tissue engineering owing to its osteoconductive properties. These properties increase the stiffness and bioactivity of polymeric hydrogels, making them ideal for the repair, replacement, and regeneration of damaged bones. In this study, we investigated the effects of incorporating silanized 45S5 bioactive glass (Si-BG) into gelatin methacrylate (GelMA) hydrogel (GelMA/Si-BG) for potential bone tissue engineering. Our findings revealed that crosslinking GelMA with Si-BG had a striking increase in bioactivity with and without osteogenic induction of human mesenchymal stem cells (hMSCs) when compared to GelMA/BG hydrogels. Meanwhile, both GelMA/Si-BG and GelMA/BG hydrogels were able to maintain the cell viability of hMSC for up to 14 days. Additionally, GelMA/Si-BG hydrogels were shown to have a significantly higher compressive modulus than GelMA/BG hydrogels. This study has demonstrated the introduction of silanized 45S5 BG into GelMA hydrogel bioactivity and mechanical properties of GelMA hydrogels, exemplifying the potential application of silanization of BG in bone tissue engineering.

Polysaccharide-Based Double-Network Hydrogels: Polysaccharide Effect, Strengthening Mechanisms, and Applications.

Polysaccharides are carbohydrate polymers that are major components of plants, animals, and microorganisms, with unique properties. Biological hydrogels are polymeric networks that imbibe and retain large amounts of water and are the major components of living organisms. The mechanical properties of hydrogels are critical for their functionality and applications. Since synthetic polymeric double-network (DN) hydrogels possess unique network structures with high and tunable mechanical properties, many natural functional polysaccharides have attracted increased attention due to their rich and convenient sources, unique chemical structure and chain conformation, inherently desirable cytocompatibility, biodegradability and environmental friendliness, diverse bioactivities, and rheological properties, which rationally make them prominent constituents in designing various strong and tough polysaccharide-based DN hydrogels over the past ten years. This review focuses on the latest developments of polysaccharide-based DN hydrogels to comprehend the relationship among the polysaccharide properties, inner strengthening mechanisms, and applications. The aim of this review is to provide an insightful mechanical interpretation of the design strategy of novel polysaccharide-based DN hydrogels and their applications by introducing the correlation between performance and composition. The mechanical behavior of DN hydrogels and the roles of varieties of marine, microbial, plant, and animal polysaccharides are emphatically explained.

DMTMM-mediated synthesis of norbornene-modified hyaluronic acid polymers to probe cell-hydrogel interactions

Synthesis of chemically modified hyaluronic acid (HA) polymers has enabled the fabrication of hydrogels, such as norbornene-modified HA (NorHA) hydrogels that can provide tunable mechanical properties. However, current protocols for the synthesis of NorHA polymers rely on the use of dimethyl sulfoxide (DMSO), a solvent that is cost-intensive and requires extensive dialysis to be removed. To address this limitation, we developed an organic solvent-free NorHA synthesis protocol based on the triazine derivative 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) which enables control over the degree of substituted norbornene groups and hydrogel mechanical properties. Our study further demonstrates the incorporation of enzymatically degradable crosslinkers to fabricate NorHA hydrogels as an in vitro platform to tune cell spreading and nascent protein deposition towards their use in tissue engineering and regenerative medicine.

PH-Dependent Friction of Polyacrylamide Hydrogels

Polyacrylamide hydrogels are widely used in biomedical applications due to their tunable mechanical properties and charge neutrality. Our recent tribological investigations of polyacrylamide gels have revealed tunable and pH-dependent friction behavior. To determine the origins of this pH-responsiveness, we prepared polyacrylamide hydrogels with two different initiating chemistries: a reduction–oxidation (redox)-initiated system using ammonium persulfate (APS) and N,N,N′N′-tetramethylethylenediamine (TEMED) and a UV-initiated system with 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959). Hydrogel swelling, mechanical properties, and tribological behavior were investigated in response to solution pH (ranging from ≈ 0.34 to 13.5). For polyacrylamide hydrogels in sliding contact with glass hemispherical probes, friction coefficients decreased from µ = 0.07 ± 0.02 to µ = 0.002 ± 0.002 (redox-initiated) and from µ = 0.05 ± 0.03 to µ = 0.003 ± 0.003 (UV-initiated) with increasing solution pH. With hemispherical polytetrafluoroethylene (PTFE) probes, friction coefficients of redox-initiated hydrogels similarly decreased from µ = 0.06 ± 0.01 to µ = 0.002 ± 0.001 with increasing pH. Raman spectroscopy measurements demonstrated hydrolysis and the conversion of amide groups to carboxylic acid in basic conditions. We therefore propose that the mechanism for pH-responsive friction in polyacrylamide hydrogels may be credited to hydrolysis-driven swelling through the conversion of side chain amide groups into carboxylic groups and/or crosslinker degradation. Our results could assist in the rational design of hydrogel-based tribological pairs for biomedical applications from acidic to alkaline conditions.Graphical abstract

Hydrogels with Reversible Crosslinks for Improved Localised Stem Cell Retention: A Review.

Successful stem cell applications could have a significant impact on the medical field, where many lives are at stake. However, the translation of stem cells to the clinic could be improved by overcoming challenges in stem cell transplantation and in vivo retention at the site of tissue damage. This review aims to showcase the most recent insights into developing hydrogels that can deliver, retain, and accommodate stem cells for tissue repair. Hydrogels can be used for tissue engineering, as their flexibility and water content makes them excellent substitutes for the native extracellular matrix. Moreover, the mechanical properties of hydrogels are highly tuneable, and recognition moieties to control cell behaviour and fate can quickly be introduced. This review covers the parameters necessary for the physicochemical design of adaptable hydrogels, the variety of (bio)materials that can be used in such hydrogels, their application in stem cell delivery and some recently developed chemistries for reversible crosslinking. Implementing physical and dynamic covalent chemistry has resulted in adaptable hydrogels that can mimic the dynamic nature of the extracellular matrix.

Curcumin-loaded methacrylate pullulan with grafted carboxymethyl-β-cyclodextrin to form hydrogels for wound healing: In vitro evaluation

A pullulan (Pul)-derivative hydrogel was developed by introducing methacrylate (MA) groups and β-cyclodextrin (βCD) to form a Pul-βCD-MA hydrogel by UV cross-linking. The MA was expected to improve the hydrogel's mechanical properties and the βCD to increase the solubility of curcumin. Pul-βCD-MA was successfully synthesized, as confirmed by the 1H NMR and FTIR spectra. Hydrogels were formed at Pul-βCD-MA concentrations of 5 %, 7.5 %, or 10 % w/v. Pul-βCD-MA showed enhanced curcumin solubility compared to Pul or Pul-MA. The morphological analysis of the hydrogel showed a porous structure. The concentration of βCD affected the hydrogels' mechanical properties, and the 7.5 % hydrogel (with or without curcumin) did not fracture. The cumulative release of curcumin in the 7.5 % Pul-βCD-MA hydrogel was 60 % over 8 h. The release profile fit the Korsmeyer-Peppas model. In vitro cytotoxicity tests revealed that hydrogels were biocompatible with human primary dermal fibroblast cells. Curcumin-loaded Pul-βCD-MA hydrogels significantly accelerated wound healing compared to Pul-βCD-MA hydrogels without curcumin loading. Therefore, the Pul derivative's hydrogel may be a promising material for wound healing.

Low-Temperature Adaptive Dual-Network MXene Nanocomposite Hydrogel as Flexible Wearable Strain Sensors.

Flexible electronic devices and conductive materials can be used as wearable sensors to detect human motions. However, the existing hydrogels generally have problems of weak tensile capacity, insufficient durability, and being easy to freeze at low temperatures, which greatly affect their application in the field of wearable devices. In this paper, glycerol was partially replaced by water as the solvent, agar was thermally dissolved to initiate acrylamide polymerization, and MXene was used as a conductive filler and initiator promoter to form the double network MXene-PAM/Agar organic hydrogel. The presence of MXene makes the hydrogel produce more conductive paths and enforces the hydrogel's higher conductivity (1.02 S·m-1). The mechanical properties of hydrogels were enhanced by the double network structure, and the hydrogel had high stretchability (1300%). In addition, the hydrogel-based wearable strain sensor exhibited good sensitivity over a wide strain range (GF = 2.99, 0-200% strain). The strain sensor based on MXene-PAM/Agar hydrogel was capable of real-time monitoring of human movement signals such as fingers, wrists, arms, etc. and could maintain good working conditions even in cold environments (-26 °C). Hence, we are of the opinion that delving into this hydrogel holds the potential to broaden the scope of utilizing conductive hydrogels as flexible and wearable strain sensors, especially in chilly environments.

Facile preparation and properties of porous poly(vinyl alcohol)/trehalose/nano-clay hydrogels with high mechanical strength for potential application in bone tissue engineering

Among various biomaterials, hydrogels are considered as the most attractive tissue engineering material due to their resemblances to extracellular matrix. However, due to the poor mechanical properties, poly(vinyl alcohol) hydrogels are restricted to be applied in load-bearing tissue repair and regeneration. In this work, we designed a series of porous biocompatible composite hydrogels with tough mechanical properties for bone tissue engineering, consisting of poly(vinyl alcohol), trehalose and nano-clay. These novelty hydrogels were prepared by a facile one-pot method. Compositions, microscopic structures, and mechanical properties of hydrogels were investigated in detail. The maximum compressive strength, compressive modulus, tensile strength, elastic modulus, and toughness of hydrogels attained about 2.71 MPa, 0.163 MPa, 0.741 MPa, 0.084 MPa, and 0.94 MJ/m3, respectively. These as-prepared hydrogels exhibited the excellent mechanical properties, which were ascribed to the hydrogen bond interactions between molecules and nano-enhancement effect of the nano-clay. Meanwhile, as-prepared hydrogels also exhibited a three-dimensional and interconnected porous microstructure, which facilitated the transport of nutrients to promote cells growth. In addition, the mechanical properties and microscopic structures of hydrogels could be controlled by adjusting the concentrations of trehalose and nano-clay. In vitro cell experiments demonstrated that the hydrogels had good biocompatibility. And hydrogels possessed the excellent ability to induce MC3T3-E1 cells osteogenesis to accelerate bone defects repair. Above illustrated results demonstrated that the potential applications of the hydrogels used as bone tissue engineering materials. Therefore, we anticipated this kind of poly(vinyl alcohol)-based composite hydrogel could develop a new strategy for bone tissue repair.

Evaluating the angiogenic and mechanical properties of hydrogels and physical constructs derived from spinal cord meninges extracellular matrix

The vasculature is an integral unit of the tissue microenvironment due to providing nutrients and oxygen to surrounding cells. Therefore, pro-angiogenic biomaterials have the potential to improve the success of a wide range of medical therapies, including tissue engineering, wound healing, and drug delivery. Herein, we decellularized bovine spinal cord meninges with Triton X-100 and digested them with pepsin to obtain a hydrogel (MeninGEL). The cryogel form of the MeninGEL was also prepared by lyophilization process (named as MeninRIX). DNA content analysis showed that the nuclear content was significantly reduced by 98.6% after decellularization process. Furthermore, the effect of decellularization on extracellular matrix components was investigated with glycosaminoglycan (GAG) and hydroxyproline (HYP) content analyses. Tensile, compression, and suture retention tests were performed to elucidate the mechanical properties. The physiological degradation behavior of the bioscaffolds was investigated by hydrolytically. Both MeninGEL and MeninRIX have good biocompatibility and pro-angiogenic properties, as proved by the Chick Chorioallantoic Membrane (CAM) assay. Moreover, SEM and histological analyses indicated cellular migration, attachment, and dynamism on the bioscaffolds’ surfaces. On the basis of these data, MeninGEL and MeninRIX are pro-angiogenic structures and have adequate mechanical properties, which makes them promising candidates for soft regenerative medicine applications.

The attractiveness of 4D printing in the medical field: Revealing scientific and technological advances in design factors and applications

Currently, there is an increasing demand in the medical field for low-cost, high-quality products as well as personalized solutions, and different manufacturing methods are being investigated to provide innovative solutions. Four-dimensional (4D) printing is a promising technology that could overcome the challenges associated with the applications of three-dimensional printing in regenerative medicine and biomedical devices. A revolution is expected in this regard, and it is essential to keep abreast of the latest developments. Under this context, the purpose of this paper is to reveal scientific and technological advances of 4D printing in the medical field using a competitive technology intelligence (CTI) methodology. To this end, publications were analyzed from the Scopus database between January 1, 2017, and May 9, 2023. The main trends were identified for both design factors and applications. In the first case, the following were considered: 4D printing methods, external stimuli, materials, mathematical models, and interaction mechanisms. In contrast, in the second case, the applications of 4D printing involved were considered: drug delivery systems, stents, and scaffolds. The obtained design factors results included improvements in mechanical properties of hydrogels by adding magnetic nanoparticles, biopolyurethane, and other materials, the development of cell-friendly bioprinting methods to print cellular structures, and the use of theoretical-experimental approaches to predict shape deformation of structures. While for applications, results included advances in the development of expandable drug delivery systems, fabrication of stents for the treatment of vascular and tracheal stenosis, and the design of scaffolds to treat cartilage defects and bone regeneration. This study provides insights to researchers, academics, and companies involved in research and development as well as innovation that are looking for new solutions to improve health by incorporating breakthrough technologies such as 4D printing.

Thermoresponsive hydrogels with sulfated polysaccharide-derived copolymers: the effect of carbohydrate backbones on the responsive and mechanical properties

Thermoresponsive hydrogels based on ionic cellulose/chitosan are widely used various fields, such as smart windows and tissue engineering, while the effect of carbohydrate backbones of cellulose/chitosan on the thermal response and mechanical properties of hydrogels has received less attention so far. Herein, poly(2(dimethylamino)ethyl methacrylate) (PDMAEMA)-grafted cellulose sulfate (P-CS) and PDMAEMA-grafted chitosan sulfate (P-CHS) as research models are successfully synthesized through multi-step reactions. The P-CS and P-CHS polymers are further applied in crosslinked polyacrylamide networks, resulting in the P-CS and P-CHS hydrogels. Compared to P-CS hydrogels, P-CHS hydrogels could obviously block the transmission of visible light when the temperature is changed from 25 to 42 °C. In contrast to P-CHS hydrogels, the P-CS hydrogels change easily from soft and weak state to stiff and strong state according to their mechanical behaviors. These results indicate that different carbohydrate backbones of cellulose and chitosan should have caused distinct aggregation behaviors of corresponding P-CS and P-CHS hydrogels, which are accompanied by different light transmittance and mechanical properties.Graphical abstract Thermoresponsive hydrogels using PDMAEMA-grafted ionic cellulose sulfate (P-CS) and chitosan sulfate (P-CHS) are successfully prepared. Distinct carbohydrate backbone displayed different effects on the thermoresponsive and mechanical properties of hydrogels.

Metal‐Organic Framework Reinforced Highly Stretchable and Durable Conductive Hydrogel‐Based Triboelectric Nanogenerator for Biomotion Sensing and Wearable Human‐Machine Interfaces

AbstractFlexible triboelectric nanogenerators (TENGs) with multifunctional sensing capabilities offer an elegant solution to address the growing energy supply challenges for wearable smart electronics. Herein, a highly stretchable and durable electrode for wearable TENG is developed using ZIF‐8 as a reinforcing nanofiller in a hydrogel with LiCl electrolyte. ZIF‐8 nanocrystals improve the hydrogel's mechanical properties by forming hydrogen bonds with copolymer chains, resulting in 2.7 times greater stretchability than pure hydrogel. The hydrogel electrode is encapsulated by microstructured silicone layers that act as triboelectric materials and prevent water loss from the hydrogel. Optimized ZIF‐8‐based hydrogel electrodes enhance the output performance of TENG through the dynamic balance of electric double layers (EDLs) during contact electrification. Thus, the as‐fabricated TENG delivers an excellent power density of 3.47 Wm–2, which is 3.2 times higher than pure hydrogel‐based TENG. The developed TENG can scavenge biomechanical energy even at subzero temperatures to power small electronics and serve as excellent self‐powered pressure sensors for human‐machine interfaces (HMIs). The nanocomposite hydrogel‐based TENG can also function as a wearable biomotion sensor, detecting body movements with high sensitivity. This study demonstrates the significant potential of utilizing ZIF‐8 reinforced hydrogel as an electrode for wearable TENGs in energy harvesting and sensor technology.

An Injectable, Shape-Retaining Collagen Hydrogel Cross-linked Using Thiol-Maleimide Click Chemistry for Sealing Corneal Perforations.

Injectable hydrogels show great promise in developing novel regenerative medicine solutions and present advantages for minimally invasive applications. Hydrogels based on extracellular matrix components, such as collagen, have the benefits of cell adhesiveness, biocompatibility, and degradability by enzymes. However, to date, reported collagen hydrogels possess severe shortcomings, such as nonbiocompatible cross-linking chemistry, significant swelling, limited range of mechanical properties, or gelation kinetics unsuitable for in vivo injection. To solve these issues, we report the design and characterization of an injectable collagen hydrogel based on covalently modified acetyl thiol collagen cross-linked using thiol-maleimide click chemistry. The hydrogel is injectable for up to 72 h after preparation, shows no noticeable swelling, is transparent, can be molded in situ, and retains its shape in solution for at least one year. Notably, the hydrogel mechanical properties can be fine-tuned by simply adjusting the reactant stoichiometries, which to date was only reported for synthetic polymer hydrogels. The biocompatibility of the hydrogel is demonstrated in vitro using human corneal epithelial cells, which maintain viability and proliferation on the hydrogels for at least seven days. Furthermore, the developed hydrogel showed an adhesion strength on soft tissues similar to fibrin glue. Additionally, the developed hydrogel can be used as a sealant for repairing corneal perforations and can potentially alleviate the off-label use of cyanoacrylate tissue adhesive for repairing corneal perforations. Taken together, these characteristics show the potential of the thiol collagen hydrogel for future use as a prefabricated implant, injectable filler, or as sealant for corneal repair and regeneration.

Hydrogelation of polypeptide-poly(ethylene glycol)-polypeptide amphiphilic triblock copolymers using L-cysteine derivatives

The hydrogelation of amphiphilic triblock copolymers based on the poly(ethylene glycol) (PEG) and the sheet-like polypeptides was studied in this report. The triblock copolymers were synthesized by ring-opening polymerization (ROP) method using PEG-diamine with two different molecular weights as the hydrophilic initiators and polypeptides of two L-cysteine derivatives (S-methyl-L-cysteine and S-benzyl-L-cysteine) as the sheet-like, hydrophobic segments. The experimental data revealed that the polymer chain length, block ratio, and functional group on the side chain would dictate the amphiphilic balance and non-covalent interactions between the polymer chains, which consequently influence the hydrogelation of triblock copolymers and their hydrogel mechanical properties. The sheet-like poly(S-benzyl-L-cysteine) (PBLC) was found to be a good hydrogelator whilst the samples containing poly(S-methyl-L-cysteine) (PMLC) could not form hydrogels with polymer concentrations below 10 wt%. This study highlighted these amphiphilic triblock copolymers synthesizing by tethering sheet-like, hydrophobic polypeptide segments on both ends of a hydrophilic polymer could be an effective strategy for preparing hydrogels with tunable properties.

Thermo-tunable Injectable Thermosensitive Hydrogel and its Application as Protein Carriers

It is known that polymer chemistries determine mechanical and physical properties of hydrogels and thus its drug delivery performance. In order to achieve desired drug release behavior, triblock copolyester PCT-PEG-PCT with proper hydrogel formulation has to be synthesized. This research has demonstrated a way to adjust hydrogel mechanical and gelation properties by simply physically mixing amphiphilic copolymers with different composition to achieve desired protein carriers. Tri-block copolymer poly (CL-co-TOSUO)-PEG-poly (CL-co-TOSUO), briefed as (PCT-PEG-PCT) with different composition have been successfully synthesized. These copolymers are thermosensitive and can form hydrogels in aqueous solution. Copolymers with higher percentage hydrophobic PCT blocks show higher mechanical stiffness and yet lower solubility. To reduce the crystallinity of the hydrophobic block and soften the hydrogel, the copolymer with long PCT blocks was physically mixed with ones with shorter PCT blocks. The polymer mixture demonstrated a moderated mechanical stiffness and desired solubility. The polymer mixture also achieved a gelation temperature at 37°C, which is desirable for drug delivery. Macromolecular drug, bovine serum albumin (BSA) was used as model drug for its release study. This protein drug was successfully loaded into the polymer mixture, and the drug release study shows the polymer mixture is able to extend a stable drug release for over 48 hours. This result confirms physical mixing of PCT-PET-PCT thermosensitive copolymers can tune gel properties and improve drug delivery performance without redesigning and synthesizing new polymers.

Glioblastoma-targeted, local and sustained drug delivery system based on an unconventional lipid nanocapsule hydrogel

The objective of this work was to develop an implantable therapeutic hydrogel that will ensure continuity in treatment between surgery and radiochemotherapy for patients with glioblastoma (GBM). A hydrogel of self-associated gemcitabine-loaded lipid nanocapsules (LNC) has shown therapeutic efficacy in vivo in murine GBM resection models. To improve the targeting of GBM cells, the NFL-TBS.40–63 peptide (NFL), was associated with LNC. The LNC-based hydrogels were formulated with the NFL. The peptide was totally and instantaneously adsorbed at the LNC surface, without modifying the hydrogel mechanical properties, and remained adsorbed to the LNC surface after the hydrogel dissolution. In vitro studies on GBM cell lines showed a faster internalization of the LNC and enhanced cytotoxicity, in the presence of NFL. Finally, in vivo studies in the murine GBM resection model proved that the gemcitabine-loaded LNC with adsorbed NFL could target the non-resected GBM cells and significantly delay or even inhibit the apparition of recurrences.

Strong, Tough, and Anti-Swelling Supramolecular Conductive Hydrogels for Amphibious Motion Sensors.

Conductive polymer hydrogels (CPHs) are widely employed in emerging flexible electronic devices because they possess both the electrical conductivity of conductors and the mechanical properties of hydrogels. However, the poor compatibility between conductive polymers and the hydrogel matrix, as well as the swelling behavior in humid environments, greatly compromises the mechanical and electrical properties of CPHs, limiting their applications in wearable electronic devices. Herein, a supramolecular strategy to develop a strong and tough CPH with excellent anti-swelling properties by incorporating hydrogen, coordination bonds, and cation-π interactions between a rigid conducting polymer and a soft hydrogel matrix is reported. Benefiting from the effective interactions between the polymer networks, the obtained supramolecular hydrogel has homogeneous structural integrity, exhibiting remarkable tensile strength (1.63MPa), superior elongation at break (453%), and remarkable toughness (5.5MJ m-3 ). As a strain sensor, the hydrogel possesses high electrical conductivity (2.16S m-1 ), a wide strain linear detection range (0-400%), and excellent sensitivity (gauge factor = 4.1), sufficient to monitor human activities with different strain windows. Furthermore, this hydrogel with high swelling resistance has been successfully applied to underwater sensors for monitoring frog swimming and underwater communication. These results reveal new possibilities for amphibious applications of wearable sensors.