Sensitive Hydrogel Research Articles

Antifreeze protein-based ultrastretchable and highly sensitive hydrogel for human-machine interaction

Intelligent and convenient human–computer interfaces realize efficient and close cooperation between people and the digital world. As windows of human–machine interaction (HMI), sensors directly determine the ability and quality of acquired signals and the utilization potential of HMI systems. However, it still remains challenging to develop antifreeze hydrogel sensors with freeze-resistant properties while avoiding the loss of other properties as much as possible to achieve stable HMI applications in low-temperature environments. Here, we present an Agar/PAAm dual-network hydrogel (Na+-Agar/PAAm-AFP) doped with both antifreeze protein (AFP) and sodium chloride (NaCl), which exhibits excellent antifreeze capability (−20 °C). The hydrogel integrates transparency (>90%), ultra stretchability (up to 2100%), good adhesion properties to metal, glass, and plastic, high electrical conductivity (3.41 S m−1), high sensitivity (GF = 10.23), and non-irritating to the skin. The hydrogel can be used for monitoring daily activities and glove-based HMI systems for intelligent control. In addition, based on this hydrogel, we have successfully developed an interactive system for real-time information transfer over long distances. It is expected to provide better health management monitoring in several fields and also help to advance the development of innovative and IoT technologies.

Abstract 2888: Sensitization of radiation resistant colon cancer - The oxygenated microbubble hydrogel approach

Abstract Background: Hypoxia, a state of reduced oxygen that develops within the tumor due to its irregular vasculature, could result in treatment resistance. Mounting evidence suggests that reoxygenation of the tumor could improve outcomes of conventional cancer therapies. Our approach combats hypoxia using oxygenated lipid microbubbles (OMB) loaded in a temperature sensitive gel. The OMB would carry the oxygen while the gel would sustain its release into the tumor microenvironment. Objectives: To formulate an oxygen loaded MB dispersed in a temperature sensitive poloxamer hydrogel for intratumoral administration. Methods: OMB were generated by first preparing a liposomal mixture DSPC:DSPE-PEG2000, which was dispersed in a thermosensitive poloxamer hydrogel (P407:P188). This was pressurized with oxygen and vortexed in a gas-tight vial. Characterizations included OMB size distribution, injectability, thermosensitivity, oxygen loading and release, and the impact of the formulation on efficacy of radiotherapy against a colon cancer cell line (HCT116) was evaluated. Results: DSPC:DSPE-PEG2000 liposomes at a molar ratio of 94:6 dispersed in P407:P188 (21:6.5 %w/w) generated OMB with a size distribution in the acceptable range of 0.8-8 µm. Formulations were within the established limits of injectability (F<38N) at room temperature, and gelled near physiological temperatures enabling a sustained release of oxygen.. The formulation co-treatment enhanced radiotherapy significantly as evidenced by the remarkable reductions of clonogenic survival rates in both hypoxic and normoxic HCT116 cells (reduction by 78% vs 68% compared to just their respective radiated controls; p<0.0001 for both cases). Conclusion: Reoxygenation with a newly developed OMB hydrogel formulation effectively sensitized HCT116 to radiotherapy in vitro. Studies are underway to explore the importance of reoxygenation rate and extent for optimal tumor sensitization. Citation Format: Ashok David Jose, Celine Hui-Ning Chong, Jagdish Jaiswal, Zimei Wu, Sachin Sunil Thakur. Sensitization of radiation resistant colon cancer - The oxygenated microbubble hydrogel approach [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2888.

Preparation and properties of polyvinyl alcohol/chitosan-based hydrogel with dual pH/NH3 sensor for naked-eye monitoring of seafood freshness

To address the issue of food spoilage causing health and economic loss, we developed a pH/NH3 dual sensitive hydrogel based on polyvinyl alcohol/chitosan (PVA/CS) containing chitosan-phenol red (CP). The CP was synthesized via Mannich reaction and immobilized it in PVA/CS hydrogel through freezing/thawing method to prepare the final PVA/CS/CP hydrogel. The synthesis of CP was confirmed by 1H NMR, FT–IR, XRD, UV–vis, and XPS. The characteristics of hydrogel were evaluated by FT–IR, XRD, SEM, mechanical properties, thermal stability, leaching, and color stability tests. The PVA/CS/CP hydrogel showed distinctly different color at various pH and NH3 vapor levels (yellow to purple). The hydrogel exhibited obvious color changes (ΔE = 46.95) in response to shrimp spoilage, stored at 4 °C. It showed positive and strong correlation between the ΔE values of the indicator hydrogel and total volatile basic nitrogen (TVB-N) as (R2 = 0.9573) and with pH as (R2 = 0.8686), respectively. These results clearly show that the PVA/CS/CP hydrogel could be applied for naked-eye real-time monitoring of seafood freshness in intelligent packaging.

Preparation, characterization and drug release properties of pH sensitive Zingiber officinale polysaccharide hydrogel beads

The aim of this study was to prepare a drug carrier that could deliver oral insulin to the intestine. A hydrogel beads composed of sodium carboxymethyl cellulose (CMC), Zingiber offtcinale polysaccharide (ZOP) and chitosan (CS) were prepared by ionic gel method as insulin carrier. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and thermogravimetric (TGA) showed that the hydrogel was formed by metal ion coordination between ZOP and CMC and Fe3+, and CS was coated on the surface of the hydrogel ball in the form of non covalent bond. The results showed that the swelling process of hydrogel spheres has significant pH sensitivity. In addition, the hydrogel beads successfully coated insulin, and the drug loading rate (DL) of (ZOP/CMC-Fe3+)@CS could reach 69.43 ± 7.32 mg/g, and the entrapment efficiency (EE) could reach 66.94 ± 7.43 %. In vitro release experiments, the release rate of (CMC/ZOP-Fe3+)@CS in simulated gastric fluid (SGF) for 2 h was <20 %, and the cumulative release rate of insulin after 9 h in simulated intestinal fluid (SIF) reached over 90 %. The results showed that the hydrogel beads prepared in this work could be used as a potential carrier for delivering oral insulin.

Robust and sensitive conductive nanocomposite hydrogel with bridge cross-linking-dominated hierarchical structural design.

Conductive hydrogels have a remarkable potential for applications in soft electronics and robotics, owing to their noteworthy attributes, including electrical conductivity, stretchability, biocompatibility, etc. However, the limited strength and toughness of these hydrogels have traditionally impeded their practical implementation. Inspired by the hierarchical architecture of high-performance biological composites found in nature, we successfully fabricate a robust and sensitive conductive nanocomposite hydrogel through self-assembly-induced bridge cross-linking of MgB2 nanosheets and polyvinyl alcohol hydrogels. By combining the hierarchical lamellar microstructure with robust molecular B─O─C covalent bonds, the resulting conductive hydrogel exhibits an exceptional strength and toughness. Moreover, the hydrogel demonstrates exceptional sensitivity (response/relaxation time, 20 milliseconds; detection lower limit, ~1 Pascal) under external deformation. Such characteristics enable the conductive hydrogel to exhibit superior performance in soft sensing applications. This study introduces a high-performance conductive hydrogel and opens up exciting possibilities for the development of soft electronics.

Background-Free and Reversible Upconversion Hydrogel Sensing Platform for Visual Monitoring of Sulfite.

Excessive sulfite usage in food and pharmaceutical production causes respiratory and neurological diseases, underscoring the need for a sensitive and rapid quantification strategy. The portable sensing platform based on a luminescent hydrogel sensor is a powerful tool for the on-site, real-time detection of sulfite ions. However, the lack of recyclability in almost all reaction-based hydrogel sensors increases the application cost. This study constructed a reversible and upconversion nanoprobe combining upconversion nanoparticles (UCNPs) and pararosaniline (PAR) for sulfite detection. The upconversion nanoprobe was further encapsulated in a three-dimensional polyacrylamide hydrogel matrix to create a background-free, reversible hydrogel sensor. The near-infrared excitation of UCNPs avoids the autofluorescence in the hydrogel and real samples. Meanwhile, PAR serves as a specific recognition unit for sulfite ions. After the addition of sulfites, a specific reaction occurs between PAR and sulfites, leading to the recovery of characteristic emission at 540 nm, achieving sensitive detection of sulfite ions. Importantly, this specific reaction is reversible under thermal treatment, allowing the hydrogel sensor to return to its initial state and thus enabling reversible detection of sulfite ions. Furthermore, a portable sensing platform is developed to realize point-of-care, real-time quantitative detection of sulfite ions. The proposed upconversion reversible hydrogel sensor provides a new sensing strategy for the detection of hazardous substances in food and offers new insights into the preparation of reversible, highly sensitive hydrogel sensors.

3D Printed Sensors for Wearable Electronics and Smart Gesture Recognition

AbstractModern materials with unique structures and functions are inspired by nature. However, nature's craftsmanship is beyond the reach of traditional handmade techniques. 3D printing technology creates the possibility of creating bionic structures. In this study, inspired by the ability of spiders to sense the capture of prey through the vibration of their webs, a spider‐web‐like, highly sensitive hydrogel sensor is designed and printed. The hydrogel is made of eco‐friendly green polyvinyl alcohol cross‐linked with microcrystalline cellulose. Surprisingly, the 3D‐printed hydrogel sensor can manipulate the sensitivity by changing the angle and strain range of the structure. Accordingly, the Gauge factor (GF) of the 3D‐printed hydrogel (θ = 60°) is up to 58.23, which is 23.9 times higher than that of the non‐3D‐printed hydrogel sensor (GF = 2.43). The GF of the 3D‐printed hydrogel at other angles still remained high at 24.74 (θ = 90°) and 12.31 (θ = 120°), respectively. It can be seen that the 3D‐printed hydrogel sensor has advanced performance. In addition, an intelligent gesture recognition system for human–computer interaction is constructed using 3D‐printed hydrogel sensors, which offers potential prospects for helping people communicate.

Preparation and Properties of Highly Stretchable, Adhesive, and Sensitive Ion-Conducting Hydrogels

Based on polyvinyl alcohol, polyacrylic acid, and sodium alginate, ion-conducting hydrogels with high stretchability and adhesion were fabricated via a two-step process. Hydrogels were prepared with different contents of cellulose nanocrystals (CNC) and sodium alginate to improve the performance of ion-conducting hydrogels. The samples were tested and analyzed by Fourier transform infrared spectrometer, universal mechanical tester, LCR digital bridge and scanning electron microscope. The results show that the addition of sodium alginate can improve the ductility and mechanical properties of the hydrogel, and with the increase of the amount of sodium alginate, the ductility of the hydrogel shows an upward trend, when the amount of sodium alginate is 0 g, when the CNC is 0, the elongation at break of the hydrogel is 201.4%, and the maximum tensile strength is 0.045 MPa. When the amount of sodium alginate was 1 g and the CNC was 0, the elongation at break of the hydrogel was 769.2%, and the maximum tensile strength reached 0.075 MPa. The addition of CNC will also improve the mechanical properties of the hydrogel, but the addition of excessive CNC will reduce the mechanical properties of the hydrogel. When containing 2 g CNC and 1 g sodium alginate (SA), the elongation at break of the hydrogel was 983.2%, and the maximum tensile strength was 0.098 MPa. When the CNC content increased to 4 g, the elongation at break of the hydrogel decreased to 698.1%, and the maximum tensile strength decreased to 0.065 MPa. When the hydrogel is stretched, the relative resistance of the hydrogel increases with the stretching deformation. And the hydrogel can still guarantee the stability of the change in multiple stretching cycles, which indicates that the hydrogel has potential application value in flexible sensors.

PH Sensitive Peptide Hydrogel Encapsulating Anti-angiogenesis Drug Conbercept and Chemotherapy Drug DOX for the Combined Treatment of Retinoblastoma

Retinoblastoma(RB) is a malignant tumor originating from retina. Radiotherapy, chemotherapy, photodynamic therapy, cryotherapy and surgery are commonly used in clinical RB treatment, but the overall efficacy is poor and often...

Biodegradable pectin-based thermo-responsive composite GO/hydrogel with mussel inspired tissue adhesion for NIR enhanced burn wound healing

Thermo-responsive hydrogels with biodegradability have great application in biomedical areas, while the Poly(N-isopropylacrylamide) (PNIPAM) based hydrogels exhibiting lower critical solution temperature (LCST) around body temperature have shown promising applications in diverse areas such as drug delivery, tissue engineering, and wound repairing. In this study, PNIPAM based thermo-responsive copolymer with ketone functional group was polymerized and the LCST was regulated to body temperature, then biodegradable self-healing hydrogels with injectability were fabricated by cross-linking the thermo-responsive copolymers with dopamine functionalized pectin hydrazide (PDAH). The hydrogel exhibited good mechanical strength, excellent biocompatibility and thermo-responsive sustained drug release process. The nano-graphene oxide (GO) was incorporated to design near-infrared (NIR) sensitive nanocomposite hydrogel to serve as photothermal enhanced wound dressing with vancomycin loading. The composite hydrogel also showed pH-responsive drug release behavior and the NIR irradiation also accelerated the release rate based on photothermal induced phase transition. More importantly, the nanocomposite hydrogel with vancomycin loading and photothermal property can promoted burn wound repairing rate by inhibiting the bacterial growth. As a result, this GO composite hydrogel (GO/hydrogel) could act as NIR triggered photo-thermal enhanced drug delivery platform for promoted wound repairing in the near future.

Electromagnetic triggering with metallic microparticles for prospective biomedical applications

Biomedical devices like microfluidic chips and externally triggered drug delivery devices can activate their drug release mechanisms using external triggers such as ultrasound, electric field, alternating magnetic field and electromagnetic radiation. This work proposes an electromagnetic triggering technique based on the interaction of electromagnetic waves with metallic microparticles that are placed under a temperatures sensitive hydrogel. The heating effect of the electromagnetic interaction results in a localized rise in temperature. The change in temperature manipulates the physical structure of the hydrogel which can be used for releasing drug particles in a drug delivery device or controlling fluid flow in a microfluidic chip. The design and operation of the device is explained with the help of Multiphysics simulations in COMSOL followed by experimental verification using sub-100-μm iron powder particles placed under 2 mm thick layer of a thermosensitive hydrogel. The primary experiments for the device operating at 2.4 GHz and 145 mW show a temperature increment of 2.7 °C after 50 min.

Stretchable and high sensitive ionic conductive hydrogel for the direction recognizable motion detection sensor

Due to the good conductivity and adjustable mechanical properties, ionic conductive hydrogel is considered an ideal candidate for use in wearable electronic devices. However, maintaining good flexibility, conductivity, and high sensitivity of electromechanical performance, though highly desirable, remains a great challenge. In this work, a zwitterionic ionic conductive hydrogel (CMHZ: chitosan/polyacrylic acid-acrylamide/ZnSO4) was prepared with excellent mechanical properties, ionic conductivity, and high sensitivity. The CMHZ showed excellent adjusted mechanical properties (up to 1210% tensile strain under 0.15 MPa, toughness 5.42 MJ/m3) and good shape-recovery ability. Meanwhile, the free-moving metal ions in the hydrogel guaranteed the CMHZ with good conductivity (33.73 mS/cm). More importantly, the unique zwitterionic structure made the hydrogel have a wide working voltage range (0 - 2.0 V), which endowed the hydrogel with a significant improvement of sensitivity up to GF = 4.22. Based on these obvious advantages, the CMHZ hydrogel was used as a stretchable sensor demonstrated high-sensitivity physiological signal detection and motion direction recognition, suggesting wide potential in flexible electronic devices.

Highly sensitive smart hydrogels with pH-tunable toughness via signaling cascade amplification

The signaling cascade amplification is a common biological phenomenon which can effectively amplify the signal intensity and trigger huge physiological feedback. Inspired by this mechanism, herein we design a simple strategy to develop highly sensitive smart hydrogels of which the mechanical performance can be finely tuned with pH. Simply composed with hydrophobic rigid monomer phenyl acrylate with pH-responsive monomer acrylic acid, the hydrogels demonstrate high mechanical performance in an acidic environment. Upon pH rising, the gels reveal remarkable softening performance by dropping 3 orders of decrease in rigidity just in a narrow pH range. Especially, the gels reveal high sensitivity to pH near the pKa of acrylic acid, with Young's modulus dropping 50 times by merely elevating pH of 0.06. After systematical mechanism investigation, it proves that the pH signal affects the toughness with a step-by-step mechanism by gradually amplifying the trigger, similar to the signaling cascade amplification in nature. The pH enhancement first brings about a growth in ionization degree, followed by the upturning of hydration level. Then, the absorbed water serves as plasticizer by mobilizing the frozen network and lowering the softening temperature. Eventually, the gels are shifted to a rubbery state and their toughness significantly decreases. Moreover, the criterion to develop such smart hydrogels is proposed, which demonstrates universality to different systems. This novel bio-mimetic mechanism, we hope, may substantially inspire the development and application of smart hydrogels.

PH sensitive cold-set hydrogels based on fibrinogen hydrolysates/carrageenan: Insights of rheology, coacervation, microstructure and antioxidant ability

In order to investigate the effect of pH treatments on the coacervation mechanism of fibrinogen hydrolysates and carrageenan complex, the cold-set hydrogels of carrageenan and fibrinogen hydrolysates derived from the hydrolysis of chymotrypsin, alcalase and flavourzyme were prepared under different pH; mechanical strength, rheological properties, gelling structure, morphological observation, and chemical action force were investigated, and the antioxidant capacity of the hydrogels was further evaluated in meat preservation model. The results indicated that the hydrogels of carrageenan and fibrinogen hydrolysates derived from the hydrolysis of alcalase (AHs) showed the largest gel strength and the best viscoelasticity at pH 7.0 compared with other pH and hydrolase treatments. FTIR spectrum revealed that AHs showed more β-sheet and β-turn at pH 7.0 among all treatments. The interaction forces of these hydrogels showed various under different pH and hydrolase treatments, and the network of AHs hydrogels at pH 7.0 was mainly stabilized by electrostatic interaction and hydrophobic interaction. SEM and AFM demonstrated that the more regular three-dimensional network with smaller pore sizes was formed in AHs at pH 7.0 compared with pH 5.0 and pH 9.0. The AHs showed the largest scavenging ability for DPPH radicals (72.4%) at pH 7.0 in vitro, and the coated meat samples with AHs significantly increased the preservation times of fresh pork and dry-cured ham during the storage by inhibiting the increase of TBARS, TVB-N, and metmyoglobin. The finding of this work is expected to broaden the application of fibrinogen hydrolysate hydrogels into the field of food industry.

Study on the Preparation and Application of Flexible Photonic Crystal Hydrogel Sensors

With the development of deformation structured color materials and sensor signal analysis, the combination of photonic crystals with optical structure characteristics and highly sensitive hydrogels in the environment can stimulate response under conditions of mechanical deformation, temperature, humidity, pH, etc. Optical-based hydrogel sensors avoid these disadvantages of conventional sensors, such as non-destructive measurements, high-speed transmission, almost interference-free, telemetry remote control, and many other advantages. This paper introduces the optical properties of photonic crystals and the synthesis of hydrogel polymers, and describes the working principle of photonic crystal hydrogel sensors. There is no systematic generalization of the direction of flexible sensors, so this paper summarizes the progress in the direction of physical, chemical, and biological sensors, and reviews the related research applications, and discusses the potential future directions and development challenges.

3D-bioprintable endothelial cell-laden sacrificial ink for fabrication of microvessel networks

Although various research efforts have been made to produce a vascular-like network structure as scaffolds for tissue engineering, there are still several limitations. Meanwhile, no articles have been published on the direct embedding of cells within a glucose sensitive sacrificial hydrogel followed by three-dimensional (3D) bioprinting to fabricate vascular structures. In this study, the hydrogel composed of reversibly crosslinked poly(ethylene glycol) diacrylate and dithiothreitol with borax and branched polyethylenimine was used as the sacrificial hydrogel to fabricate vascular-like network structure. The component proportion ratio of the sacrificial hydrogel was optimized to achieve proper self-healing, injectable, glucose-sensitive, and 3D printing properties through the balance of boronate ester bond, hydrogen bond, and steric hinderance effect. The endothelial cells (ECs) can be directly embedded into sacrificial hydrogel and then bioprinted through a 110 μm nozzle into the neural stem cell (NSC)-laden non-sacrificial hydrogel, forming the customized EC-laden vascularized microchannel (one-step). The EC-laden sacrificial hydrogel was dissolved immediately in the medium while cells kept growing. The ECs proliferated well within the vascularized microchannel structure and were able to migrate to the non-sacrificial hydrogel in one day. ECs and NSCs interacted around the vascularized microchannel to form capillary-like structure and vascular-like structure expressing CD31 in 14 d. The sacrificial hydrogel conveniently prepared from commercially available chemicals through simple mixing can be used in 3D bioprinting to create customized and complex but easily removable vascularized structure for tissue engineering applications.

Self-healing, ultra-stretchable, and highly sensitive conductive hydrogel reinforced by sulfate polysaccharide from Enteromorpha prolifera for human motion sensing

The synthesis of multifunctional conductive hydrogel has attracted extensive attention worldwide due to their integrated properties of stretchability, self-adhesion, self-healing, and high sensitivity, while it is still a challenge. Although various kinds of polysaccharides and their derivatives are used to achieve the aforementioned objective, there are few researches about hydrogel design introducing sulfated polysaccharide from Enteromorpha prolifera (SPE), which is rich in hydroxyl, sulfate, and carboxyl groups providing amounts of reaction sites for hydrogel synthesis. Herein, conductive hydrogel (PAA-Al3+-SPE3) reinforced by SPE was designed by simple one pot hot polymerization method. This hydrogel demonstrated charming extension ratio (up to 4027.40 %), strain stress (up to 59.94 kPa), compressive strength (19.71 Mpa), and high conductivity sensibility (GF 6.76, 300 % - 700 %). Additionally, PAA-Al3+-SPE3 showed good self-healing property (repaired autonomously after 60 s) and satisfied self-adhesion (31.11 kPa) due to the reversible hydrogen bonds and metal coordination interactions. Furthermore, the PAA-Al3+-SPE3 hydrogel showed great real-time sensing performance to monitor various motions. These findings suggest the potential of PAA-Al3+-SPE3 hydrogel as an affordable and reliable conductive sensing material. Meantime, the first utilization of SPE to construct flexible wearable sensors offers new route for the high-value application of Enteromorpha prolifera.

P07.08.A DEVISING AN EXOSOMES CONTROLLED-RELEASE HYDROGEL FOR GLIOBLASTOMA THERAPY

Abstract BACKGROUND An efficient therapeutic method for glioblastoma hasn’t been founded. Nowadays, the combination of tumor surgery resection and chemoradiotherapy show limited outcomes even implanting a drug-loaded wafer on the tumor resection cavity during the surgery. Although Local drug delivery improves the adverse effects of intravenous chemotherapy drug injection, the low efficiency of drug transmembrane transportation still leads to poor therapeutic outcomes. Meanwhile, the stiff wafer is not able to perfectly match the irregular shape of the resection cavity. Recently, drug-loaded nanoparticles coated by tumor-derived exosomes applied in tumor-targeting drug delivery were frequently reported. The unique feature of tumor-homing, immune evasion of tumor-derived exosomes was used to improve the delivery efficiency, however, the therapeutic efficiency is weakened by liver filtration and the blood-brain barrier. MATERIAL AND METHODS For enhancing the therapeutic efficacy and compatibility of tumor resection cavity, in this project, a novel injectable hydrogel carrying DOX-loaded nanoparticles coated by tumor-derived exosomes, called Exo-DMSNs@CS, for intra-operative therapy of glioblastoma was devised. The doxorubicin-loaded nanoparticles encapsulated by tumor-derived exosomes (Exo-DMSNs) were integrated into body-temperature sensitive chitosan hydrogel, then injected into the tumor resection cavity and gelation along the shape. By passing the blood-brain barrier, the therapeutic efficacy can be improved by elevating the delivery efficiency induced by the released tumor-targeting Exo-DMSNs. RESULTS The hydrogel Exo-DMSNs@CS was successfully fabricated and contained features of thermosensitive, in vivo controlled releasing, in vitro tumor-targeting, and biocompatible. For simulating the scenario of intra-operative therapy, the Exo-DMSNs@CS was evaluated in the mice orthotopic GBM resection model. The decreased relapse speed and extended survival showed in the Exo-DMSNs@CS compared to DMSNs@CS demonstrated that the tumor-exosomes improve the prognosis of the mice. Moreover, the acceptable side effect was also confirmed. CONCLUSION The Eco-DMSNs@CS is suitable for therapy with better efficiency compared to traditional local drug delivery. This research provides a new strategy for glioblastoma patients and data support for similar product devising.

A stretchable, environmentally tolerant, and photoactive liquid metal/MXene hydrogel for high performance temperature monitoring, human motion detection and self-powered application

Conductive gels have received extensive attention in flexible electronics due to their diverse characteristics. The requirement for versatility and incompatibility of the conductive fillers with the hydrogel matrix remain a challenge for hydrogels. Herein, the cellulose nanofiber stabilized liquid metal droplets are utilized to initiate the polymerization and simultaneously serve as solid conductive fillers to construct the polyacrylamide/MXene/glycerol hydrogel with eligible stretchability (1000%) and high environmental adaptability (−25 to 80 °C) for multifunctional sensing. The hydrogel is utilized as a flexible electrode to construct the triboelectric nanogenerator for mechanical energy harvesting and conversion as well as self-powered sensing. Importantly, as a versatile sensor, it combines temperature sensing and deformation sensing with a wide range of stimulus responses and exceptional sensing performance. The flexible temperature and strain sensors are realized with superior thermosensitivity and strain sensitivity. In addition, the hydrogel exhibits favorable photothermal antibacterial ability. This work opens new avenues for the preparation of photothermal, conductive, stress and thermal sensitive hydrogels for multimodal sensors, sketching a promising future for them in flexible and wearable electronics.

Osteogenic effects of covalently tethered rhBMP-2 and rhBMP-9 in an MMP-sensitive PEG hydrogel nanocomposite

While bone morphogenic protein-2 (BMP-2) is one of the most widely studied BMPs in bone tissue engineering, BMP-9 has been purported to be a highly osteogenic BMP. This work investigates the individual osteogenic effects of recombinant human (rh) BMP-2 and rhBMP-9, when tethered into a hydrogel, on encapsulated human mesenchymal stem cells (MSCs). A matrix-metalloproteinase (MMP)-sensitive hydrogel nanocomposite, comprised of poly(ethylene glycol) crosslinked with MMP-sensitive peptides, tethered RGD, and entrapped hydroxyapatite nanoparticles was used. The rhBMPs were functionalized with free thiols and then covalently tethered into the hydrogel by a thiol-norbornene photoclick reaction. rhBMP-2 retained its full bioactivity post-thiolation, while the bioactivity of rhBMP-9 was partially reduced. Nonetheless, both rhBMPs were highly effective at enhancing osteogenesis over 12-weeks in a chemically-defined medium. Expression of ID1 and osterix, early markers of osteogenesis; collagen type I, a main component of the bone extracellular matrix (ECM); and osteopontin, bone sialoprotein II and dentin matrix protein I, mature osteoblast markers, increased with increasing concentrations of tethered rhBMP-2 or rhBMP-9. When comparing the two BMPs, rhBMP-9 led to more rapid collagen deposition and greater mineralization long-term. In summary, rhBMP-2 retained its bioactivity post-thiolation while rhBMP-9 is more susceptible to thiolation. Despite this shortcoming with rhBMP-9, both rhBMPs when tethered into this hydrogel, enhanced osteogenesis of MSCs, leading to a mature osteoblast phenotype surrounded by a mineralized ECM. Statement of significanceOsteoinductive hydrogels are a promising vehicle to deliver mesenchymal stem cells (MSCs) for bone regeneration. This study examines the in vitro osteoinductive capabilities when tethered bone morphogenic proteins (BMPs) are incorporated into a degradable biomimetic hydrogel with cell adhesive ligands, matrix metalloproteinase sensitive crosslinks for cell-mediated degradation, and hydroxyapatite nanoparticles. This study demonstrates that BMP-2 is readily thiolated and tethered without loss of bioactivity while bioactivity of BMP-9 is more susceptible to immobilization. Nonetheless, when either BMP2 or BMP9 are tethered into this hydrogel, osteogenesis of human MSCs is enhanced, bone extracellular matrix is deposited, and a mature osteoblast phenotype is achieved. This bone-biomimetic hydrogel is a promising design for stem cell-mediated bone regeneration.