Thermoreversible Properties Research Articles

A novel m-xylylene-diamine/glucose based-supramolecular eutectogels with tissue clearing for three dimensional histological imaging

Hydrogel-based tissue clearing technologies have shown significant promise for deep-tissue imaging and subcellular-level optical 3D reconstruction of whole organs. This study proposes a novel approach utilizing a deep eutectic solvent (DES) formulated with glucose and m-xylylene-diamine (MXDA) to create a highly efficient tissue-clearing hydrogel system named the passive hydrogel clearing system (PHCS). PHCS achieved efficient tissue clearing through a single-step tissue gelation process. The resulting hydrogel-tissue complex exhibited thermoreversible properties, transitioning into a sol state upon heating and vice versa upon cooling. Notably, PHCS enabled media embedding, facilitating immunofluorescence histopathology. Additionally, the system demonstrated compatibility with various fluorescent probes, particularly lipophilic dyes. Our study successfully employed PHCS for the reconstruction of vascular structures within the intestine, enabling the generation of a 3D pathology model. These findings suggest that PHCS is a promising novel method for fabricating hydrogels for tissue clearing and holds great potential for application as a mounting medium for morphological imaging.

Temperature- and pH-induced dual-crosslinked methylcellulose/chitosan-gallol conjugate composite hydrogels with improved mechanical, tissue adhesive, and hemostatic properties

Gauze or bandages are commonly used to effectively control bleeding during trauma and surgery. However, conventional treatment methods can sometimes lead to secondary damages. In recent years, there has been increased interest in developing adhesive hemostatic hydrogels as a safer alternative for achieving hemostasis. Methylcellulose (MC) is a well-known thermo-sensitive polymer with excellent biocompatibility that is capable of forming a hydrogel through physical crosslinking owing to its inherent thermo-reversible properties. However, the poor mechanical properties of the MC hydrogel comprising a single crosslinked network (SN) limit its application as a hemostatic material. To address this issue, we incorporated a chitosan-gallol (CS-GA) conjugate, which has the ability to form chemical crosslinks through self-crosslinking reactions under specific pH conditions, into the MC hydrogel to reinforce the MC hydrogel network. The resulting MC/CS-GA hydrogel with a dual-crosslinked network (DN), involving both physical and chemical crosslinks, exhibited synergistic effects of the two types of crosslinks. Thus, compared with those of the SN hydrogel, the composite DN hydrogel exhibited significantly enhanced mechanical strength and tissue adhesive properties. Moreover, the DN hydrogel presented excellent biological activity in vitro. Additionally, in rat hepatic hemorrhage models, the DN hydrogel exhibited high hemostatic efficiency, showcasing its multifunctional capabilities.

Robust, Efficient, and Recoverable Thermocells with Zwitterion-Boosted Hydrogel Electrolytes for Energy-Autonomous and Wearable Sensing.

The rapid growth of flexible quasi-solid-state thermocells (TECs) provides a fresh way forward for wearable electronics. However, their insufficient mechanical strength and power output still hinder their further applications. This work demonstrates a one-stone-two-birds strategy to synergistically enhance the mechanical and thermoelectrochemical properties of the [Fe(CN)6]3-/4--based TECs. By introducing Hofmeister effect and multiple non-covalent interactions via betaine zwitterions, the mechanical strength of the conventional brittle gelatin hydrogel electrolytes is substantially improved from 50 to 440 kPa, with a high stretchability approaching 250 %. Meanwhile, the betaine zwitterions strongly affect the solvation structure of [Fe(CN)6]3- ions, thus enlarging the entropy difference and raising the thermoelectrochemical Seebeck coefficient from 1.47 to 2.2 mV K-1. The resultant quasi-solid-state TECs exhibit a normalized output power density of 0.48 mW m-2 K-2, showing a notable improvement in overall performance compared to their counterparts without zwitterion regulation. The intrinsic thermo-reversible property also allows the TECs to repeatedly self-recover through sol-gel transformations, ensuring reliable energy output and even recycling of TECs in case of extreme mechanical damages. An energy-autonomous smart glove consisting of eighteen individual TECs is further designed, which can simultaneously monitor the temperature of different positions on any touched object, demonstrating high potential in wearable applications.

One-Pot Synthesis of a Robust Crosslinker-Free Thermo-Reversible Conducting Hydrogel Electrode for Epidermal Electronics.

Traditional epidermal electrodes, typically made of silver/silver chloride (Ag/AgCl), have been widely used in various applications, including electrophysiological recordings and biosignal monitoring. However, they present limitations due to inherent material mismatches with the skin. This often results in high interface impedance, discomfort, and potential skin irritation, particularly during prolonged use or for individuals with sensitive skin. While various tissue-mimicking materials have been explored, their mechanical advantages often come at the expense of conductivity, resulting in low-quality recordings. We herein report the facile fabrication of conducting and stretchable hydrogels using a "one-pot" method. This approach involves the synthesis of a natural hydrogel, termed Golde, composed of abundant and eco-friendly components, including gelatin, chitosan, and glycerol. To enhance the conductivity of the hydrogel, various conducting materials, such as poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS), thermally reduced graphene (TRG), and MXene, are introduced. The resulting conducting hydrogels exhibit remarkable robustness, do not require crosslinkers, and possess a unique thermo-reversible property, simplifying the fabrication process and ensuring enhanced long-term stability. Moreover, their fabrication is sustainable, as it employs environmentally friendly materials and processes while retaining their skin-friendly characteristics. The resulting hydrogel electrodes were tested for electrocardiogram (ECG) signal acquisition and outperformed commercial electrodes even when implemented in an all-flexible electrode setup simply using copper tape, owing to their inherent adhesiveness.

Thermoreversible XNBR-based conductive composites with dual dynamic networks for strain sensors

Endowing conductive composites with thermoreversible properties is important for improving the stability and extending the service life of the material, and is in line with today's concept of green chemistry....

Thermally reversible hydrogels printing of customizable bio-channels with curvature

Replicating intricate bio-channels, akin to expansive vascular networks, offers numerous advantages including self-repair, replacing damaged bio-channels, testing drugs, and biomedical devices. But, crafting multi-sized, editable bio-channels with specific curvatures, particularly using natural polymer-based bio-inks, poses a significant challenge. To address this, this study introduces a temperature-driven indirect printing method, exemplified by the diploic vein. Here, K-carrageenan (kca)-silk fiber (SF)-hyaluronic acid (HA)/hFOB 1.19 (SV40 transfection of human osteoblasts) and kca-collagen-HA/HUVECs (human umbilical vein endothelial cells) are employed to fabricate vascular-like walls and lumens, utilizing their thermoreversible properties to create multi-stage bifurcated lumens. Precise spatial curvature was generated by heating the vascular network wrapped in poly(N-isopropyl acrylamide) (PNIPAAm)-poly(ethylene glycol) diacrylate (PEGDA). Since temperature is specific to the thermal material carrying the cells, the rheological properties of bioinks, modeling temperature parameters, and their impact on printing size was explored. Additionally, mechanical properties and curvature response were characterized to determine the necessary process parameters for achieving the desired size. Ultimately, in vitro bioprinting experiments involving HUVECs and hFOB 1.19 demonstrate cell viability, adhesion, proliferation, and migration within the intraluminal hydrogel scaffold. This approach allows for customizing bio-channel content and controlling curvature programming, providing new prospects for in vitro biochannel production, with potential benefits for pathology research.

Mechanism for gel formation of pectin from mealy and crisp lotus rhizome induced by Na+ and D-glucono-d-lactone

Lotus rhizome residue, a cell wall material produced during the production of lotus rhizome starch, has long been underutilized. This study aims to extract pectin-rich polysaccharides from the cell wall of lotus rhizome and investigate their gelation mechanism in order to improve their industrial applicability. The results indicated that both CP and MP (pectin extracted from crisp and mealy lotus rhizome) exhibited a highly linear low methoxyl pectin structure, with the primary linkage mode being →4)-GalpA-(1→. The pectin chains in MP were found to be more flexible than those in CP. Then the impact of Na+, D-glucono-d-lactone (GDL), urea, sodium dodecyl sulfate (SDS), either individually or in combination, on the rheological characteristics of gels was evaluated. The results indicated that gels induced by GDL exhibited favorable thermoreversible properties, whereas the thermoreversibility of Na+-induced gels is poor. In addition to hydrogen bonding and ionic interactions, hydrophobic interactions also play a significant role in the formation of pectin gels. This study offers theoretical guidance and methodologies to improve the utilization rate of lotus rhizome starch processing by-products, while also provides novel insights into the correlation between LMP structure and gelation mechanism.

Lentil protein concentrate + pectin gels dried with SC-CO2: Influence of protein-polysaccharide interactions on the characteristics of aerogels

This study investigated the interactions of lentil protein concentrate (LPC) and pectin hydrogels and their influence on the physico-chemical characteristics of aerogels. First, emulsion gels were formed using high-intensity ultrasound (HIUS) and the impact of HIUS nominal power, and concentrations of LPC and pectin on the gelation were evaluated. Then, the emulsion gels were dried using supercritical CO2 (SC-CO2) and the density, surface area, crystallinity index, microstructure and oil and water absorption capacities of the aerogels formed were evaluated. Overall, there was no significant effect of HIUS power on the viscoelastic behavior of the emulsion gels. The emulsion gels exhibited shear-thinning behavior and had thermo-reversible property. The FT-IR spectra of the aerogels showed predominant β-sheets, responsible for the non-covalent bond formation. The aerogels had semi-crystalline structure, densities of 0.0009–0.003 g/mm3 and surface area of 2.4–7.6 m2/g. The LPC-pectin interactions can be explored to form tailor-made aerogels for bioactive delivery.

Thermoreversible Gels Based on Chitosan Copolymers as "Intelligent" Drug Delivery System with Prolonged Action for Intramuscular Injection.

Thermosensitive gels based on copolymers (PEG-chitosan, chitosan-polyethylenimine, chitosan-arginine and glycol-chitosan-spermine) are presented as promising polycations for the formation of DNA polyplexes and the potential for the development of drugs with prolonged release (up to 30 days). Being in liquid form at room temperature, such compounds can be injected into muscle tissue with rapid gel formation at human body temperature. An intramuscular depot is formed with a therapeutic agent that provides a gradual release of the drug, such as an antibacterial or cytostatic. The physico-chemical parameters of the formation of polyplexes between polycationic polymers of various compositions and molecular architecture and DNA were studied via FTIR, UV-vis and fluorescence spectroscopy using the dyes rhodamine 6G (R6G) and acridine orange (AO). The competitive displacement of AO from AO-DNA complexes showed that, with a ratio of N/P = 1, most of the DNA is bound to a polycation. During the formation of polyplexes, the DNA charge is neutralized by a polycation, which is reflected in electrophoretic immobility. The cationic polymers described in this work at a concentration of 1-4% are capable of forming gels, and the thermoreversible property is most characteristic of pegylated chitosan. BSA, as a model anionic molecule, is released by half in 5 days from the Chit5-PEG5 gel; full release is achieved in 18-20 days. At the same time, in 5 days, the gel is destroyed up to 30%, and in 20 days, by 90% (release of chitosan particles). For the first time, flow cytometry was used to study DNA polyplexes, which showed the existence of fluorescent particles in a much larger number in combination with free DNA. Thus, functional stimulus-sensitive polymers are potentially applicable for the creation of prolonged therapeutic formulations for gene delivery systems, which were obtained. The revealed regularities appear to be a platform for the design of polyplexes with controllable stability, in particular, fulfilling the requirements imposed for gene delivery vehicles.

The role of amide groups in the mechanism of acid-induced pectin gelation: A potential pH-sensitive hydrogel based on hydrogen bond interactions

Gelation of amidated pectin in the acid environment with the absence of calcium has been found, but the mechanism and gel properties are still not fully understood, especially the role of amide groups. In this study, a series of pectins with different degrees of amidation (DA) were prepared by ammonia reaction, and their structural characteristics including neutral sugar contents, molecular weight contribution, and molecular morphology were fully identified. Acid-induced hydrogels with various DA were then obtained to investigate the impact of amino groups on pectin gelation. Results showed that the higher the DA, the faster the gelation process, and the more stable the gel network. Dynamic rheological and pH stability tests confirmed the essential roles of low pH value (<3.5) and high DA (>49.76%) on the amidated pectin gelation without calcium. Hydrogen bonds were identified as the main interaction for the amidated gel mechanism and enabled the thermo-reversible properties of amidated gels. High content of amide groups allowed the formation of a denser gel network structure with greater mechanical strength, stronger thermo-reversibility, and higher pH stability.

Methionine-Derived Organogels as Lubricant Additives Enhance the Continuity of the Oil Film through Dynamic Self-Healing Assembly.

(S)-2-((1-(Hexadecylamino)-4-(methylthio)-1-oxobutan-2-yl)carbamoyl)benzoic acid (HMTA) was efficiently synthesized and successfully applied as an additive to several types of blank lubricant oils. Initially, HMTA self-assembles to fibrous structures and traps blank lubricant oils to form gel lubricants. The prepared gel lubricants show thermo-reversible properties and enhanced lubricating performance by 3∼5-fold. X-ray photoelectron spectrometry of the metal surface and the quartz crystal microbalance illustrated that there are no obvious interactions between HMTA and the metal surface. The results of Fourier transform infrared spectroscopy and X-ray diffraction further confirm that inter/intro-molecular H-bonding interactions are the main driving force for the self-healing of HMTA. Finally, molecular dynamics (MD) simulations show that the number of noncovalent H-bonding interactions fluctuates with time, and this highly dynamic H-bonding network could regulate the self-assembly process and result in the self-healing property of the HMTA organogel, which is consistent with the results of the step-strain tests. Especially, the Hirshfeld independent gradient model method at the quantum level demonstrated that C8/C9 aromatics of 500SN have strong π-π stacking interactions with the aromatic heads of HMTA and van der Waals interactions with the hydrophobic tails of HMTA, which disrupt the self-assembly behavior of the 500SN model. Therefore, the calculation studies offer a rational explanation for the superior lubricant property of the PAO10 gel as compared to that for 500SN.

Lower Critical Solution Temperature Tuning and Swelling Behaviours of NVCL-Based Hydrogels for Potential 4D Printing Applications.

The phase transitions of poly (N-vinyl caprolactam) (PNVCL) hydrogels are currently under investigation as possible materials for biomedical applications thanks to their thermosensitive properties. This study aims to use the photopolymerisation process to simulate the 4D printing process. NVCL-based polymers with different thermal properties and swellability were prepared to explore the possibility of synthetic hydrogels being used for 4D printing. In this contribution, the thermal behaviours of novel photopolymerised NVCL-based hydrogels were analysed. The lower critical solution temperature (LCST) of the physically crosslinked gels was detected using differential scanning calorimetry (DSC), ultraviolet (UV) spectroscopy, and cloud point measurement. The chemical structure of the xerogels was characterised by means of Fourier transform infrared spectroscopy (FTIR). Pulsatile swelling studies indicated that the hydrogels had thermo-reversible properties. As a result, the effect of varying the macromolecular monomer concentration was apparent. The phase transition temperature is increased when different concentrations of hydrophilic monomers are incorporated. The transition temperature of the hydrogels may allow for excellent flexibility in tailoring transition for specific applications, while the swelling and deswelling behaviour of the gels is strongly temperature- and monomer feed ratio-dependent.

BIOPHARMACEUTICAL STUDY OF BINARY POLOXAMER SYSTEMS AS IN SITU DRUG DELIVERY SYSTEMS POLOXAMER POLYCOMPLEXES: THE STUDY

Objective: The article presents the results of studying the parameters of in situ systems based on poloxamers. Methods: Natural, synthetic and semi-synthetic polymers were considered as additional gel-forming agents. The above-mentioned agents were cellulose derivatives, as well as rare-cross-linked acrylic polymers, alginic acid salts, and xanthan gum. The gelation temperature was visually recorded during the gradual heating. Mucoadhesion was determined by measuring the separation force of the sample from the mucosal model using pig stomach mucin. The concentration of gel formation was determined using an Ostwald capillary viscometer. Results: During the experiment, 20 samples based on poloxamer 407 18% were examined with the addition of excipients in concentrations of 0.5-2.0%. It was found that the introduction of additional gel-forming agents has a positive effect on the mucoadhesive properties of poloxamer 407. To increase the temperature of gelation of the binary mixture, it is necessary to take into account the own concentration of gelation of the introduced additional polymer, which was confirmed by capillary viscometry. Also, additional viscometric studies revealed the reasons for the absence of a thermoreversible effect in the composition of a poloxamer with xanthan gum and confirmed its use as an excipient in the thermoreversible matrix of poloxamer 407 is impractical. Composition with the best-investigated biopharmaceutical properties-the composition with HEC in a concentration of 0.5% Conclusion: The obtained results can be explained by the fact that when the concentration of additional polymer was exceeded, binary mixtures showed a decrease in the gel formation temperature up to a complete loss of the ability to temperature-dependent sol-gel transition. The choice of an additional gel-forming agent to improve the properties of the system should be based on some specific properties that affect the thermoreversible properties of the system.

Enhancing gel strength of Thermoproteus uzoniensis 4-α-glucanotransferase modified starch by amylosucrase treatment

4-α-glucanotransferase is used to produce thermoreversible starch gels to alleviate limitations to use of starch gels in repetitively heat-processed foods. However, the gel strength was weakened after this enzyme modification. In the present study, treatment by amylosucrase (NpAS) of corn starch and sucrose was applied to retain the gel thermoreversibility and eliminate the shortcoming caused by 4-α-glucanotransferase (TuαGT). Changes in molecular structure, rheological and retrogradation properties of modified starch were investigated after NpAS and TuαGT sequential and one-pot treatment, respectively. The apparent amylose content was reduced and increased by sequential and one-pot treatments, respectively, compared to single TuαGT modification. Chain length profiles showed higher proportion of degree of polymerization (DP) ≥ 13 by sequential treatment, whereas DP 6–12 was higher after one-pot treatment. All modified starches had reduced molecular weight. G' and G“ increased by dual enzyme compared to single TuαGT treatment having little effect on retrogradation. Interestingly, starch subjected to 3 h one-pot treatment caused G' and G" temperature curves to cross-over, improving thermoreversible properties. The results indicate that NpAS treatment compensated for loss of starch gel strength caused by TuαGT and offered possibility to provide a wider range of thermoreversible starches.

Desalination of salted duck egg white assisted by gelatin: Foaming and interface properties of the mixed system

The reutilization of salted duck egg whites is still an important challenge facing the egg product industry. Efficient desalination of salted duck egg white is an effective way to make high-value use of the by-product in the food manufacturing. In this work, benefit from the thermoreversible properties of gelatin (GEL), salted duck egg white (SDEW) was blended with GEL to desalt after forming gels (4 °C). After the temperature was restored, the egg white was recovered to liquid after desalting, which still maintained the functional properties. Using this simple method, the desalination rate reached from 92.85% to 95.75% after 6 h soaking, and the protein loss rate was about 0.197–0.366%. Compared with the control group (only containing SDEW or GEL), salted egg white/gelatin mixed solution after desalination (DDG) had higher foaming capability and foaming stability at different concentrations of gelatin and salted egg whites. This indicated that egg whites still had good foaming properties after desalination. The following interfacial properties demonstrated DDG could adsorb to the air-water interface and formed a viscoelastic surface layer. Additionally, DDG (1 mg/mL) prepared from egg white and gelatin had a unique interfacial expansion rheological behavior. Herein, this study provides a new path for SDEW desalination through physical technology, which of course broadens the utilization of salted duck egg white.

3D Printable and Biocompatible Iongels for Body Sensor Applications

AbstractSoft‐ionic materials with biocompatibility and 3D printability are needed to develop next‐generation devices to interface between electronic and biological signals. Herein, thermoreversible and biocompatible ionic liquid gels or iongels, which can be processed by direct ink writing are reported. The iongels are designed by taking advantage of polyvinyl alcohol/phenol interactions to gelify biocompatible cholinium carboxylate ionic liquids. The obtained iongels are stable, soft, and flexible materials (Young modulus between 14 and 70 kPa) with high ionic conductivity (1.8 × 10–2 S cm–1). Interestingly, they presented thermoreversible properties with gel–sol transitions ranging from 85 and 110 °C, which allows the iongel processing via direct ink writing 3D printing by material extrusion at temperatures over its transition. These 3D printable iongels are integrated into a variety of body sensors applications, namely pressure sensors, motion sensors and electrodes for electrophysiological recordings. The iongels are used as pressure sensors with a sensitivity of 0.1 kPa–1, ten times higher than that of others similar materials reported so far; showing its ability to detect human motion. Furthermore, the iongels showed excellent performance in electrodes for electrocardiography (ECG) recording, presenting good stability over time with electrocardiographic waves maintained their typical shape even after weeks.

A Survey on Mucoadhesive Thermoreversible Drug Delivery System with special Emphasis on Recto-Anal Region for the Treatment of Internal Hemorrhoids

The concept of combination of thermo reversibility and mucoadhesion has achieved a much valuable interest in various fields of pharmaceutics. Mucoadhesive drug delivery systems interact with the mucus layer covering the mucosal epithelial surface, and mucin molecules and increase the residence time of the dosage form at the site of absorption. Thermoreversible gels are the hydrogels that are liquids at room temperature but undergo gelation when in contact with body fluids or change in pH. A major problem faced by conventional formulation in various routes of administration viz. nasal, ocular, vaginal, rectal, etc is drainage of instilled formulation, poor patient compliance as in the case of vaginal and rectal delivery system. Also, blurred vision and irritation to mucosa is observed in the case of ocular and nasal delivery respectively. The drainage of the formulation results in inaccurate dose delivery thus decreasing the bioavailability of the drug which demands an increase in the frequency of the administration. To overcome these limitations, there is need of novel delivery system such as thermoreversible mucoadhesive insitu gel which provides an ease of administration and improved patient compliance as these smart delivery system is free flowing liquid at ambient temperature and gels at physiological temperature which is higher than the LCST (low critical solution temperature) of thermoreversible polymer. The combined effect of mucoadhesion and thermoreversible property will enhance prolongation of residence time of dosage form and the accuracy of the dose in body cavity respectively, leading to increased bioavailability of the drug. This review focuses on benefits of mucoadhesive thermoreversible system of drug delivery through rectum for the treatment of internal hemorrhoids.

Application of Pickering emulsions in 3D printing of personalized nutrition. Part I: Development of reduced-fat printable casein-based ink

The application of surface-active biopolymers supports opportunities and novel prospects to generate a well-defined printable ink for 3D printing. In this regard, an ideal ink must show pseudoplastic, viscoelastic, and thixotropic characters with a recoverable structure so as to be effectively printed with desired printability. Here, microcrystalline cellulose was hydrophobically modified through a facile and sustainable acetylation method. Then, the functionalized microcrystalline cellulose was incorporated into a casein-based emulsion for being replaced to its partial fat (15–60% fat reduced). The significant effect of micro-biosurfactant on the rheological properties of casein-based emulsion enhanced its shear-thinning, thixotropic, and viscoelastic features. The use of higher ratios of micro-biosurfactant produced an emulsion with greater elastic modulus, smaller droplet sizes, improved stability to the permanent deformation, and increased the nonlinear behavior of the system under large amplitude oscillatory shear stress. The results of the temperature ramp also confirmed the thermo-reversible property of the ink, which was noticeably dependent on the ratios of micro-biosurfactant. The results of this study provided fundamental knowledge about emulsion stability in terms of the contribution of the hydrophobically modified microcrystalline cellulose to interface stability and in promoting resistance to shear stress and deformation. These results allow one to gain a profound understanding of the printability and extrudability of these classes of biomaterials.

Dual-crosslinked 3D printed gelatin scaffolds with potential for temporomandibular joint cartilage regeneration

A promising alternative to current treatment options for degenerative conditions of the temporomandibular joint (TMJ) is cartilage tissue engineering, using 3D printed scaffolds and mesenchymal stem cells. Gelatin, with its inherent biocompatibility and printability has been proposed as a scaffold biomaterial, but because of its thermoreversible properties, rapid degradation and inadequate strength it must be crosslinked to be stable in physiological conditions. The aim of this study was to identify non-toxic and effective crosslinking methods intended to improve the physical properties of 3D printed gelatin scaffolds for cartilage regeneration. Dehydrothermal (DHT), ribose glycation and dual crosslinking with both DHT and ribose treatments were tested. The crosslinked scaffolds were characterized by chemical, mechanical, and physical analysis. The dual-crosslinked scaffolds had the highest degree of crosslinking and the greatest resistance to hydrolytic and enzymatic degradation. Compared to the dual-crosslinked group, the ribose-crosslinked scaffolds had thinner printed strands, larger pore surface area and higher fluid uptake. The compressive modulus values were 2 kPa for ribose, 37.6 kPa for DHT and 30.9 kPa for dual-crosslinked scaffolds. None of the crosslinking methods had cytotoxic effects on the seeded rat bone marrow-derived mesenchymal stem cells (rBMSC). After 4 and 7 d, the dual-crosslinked scaffolds exhibited better cell proliferation than the other groups. Although all scaffolds supported chondrogenic differentiation of rBMSC, dual-crosslinked scaffolds demonstrated the lowest expression of the hypertrophy-related collagen 10 gene after 21 d. The results show that 3D printed gelatin scaffolds, when dually crosslinked with ribose and DHT methods, are not toxic, promote chondrogenic differentiation of rBMSC and have potential application in tissue engineering of TMJ condylar cartilage.

Self-assembly and thermoreversible rheology of perfluorocarbon nanoemulsion-based gels with amphiphilic copolymers

Perfluorocarbon (PFC) nanoemulsions have great potential in biomedical applications due to their unique chemical stability, biocompatibility, and possibilities for enhanced oxygen supply. The addition of amphiphilic block copolymers promotes the formation and long-term stability of emulsion-based gels. In this work, we report the systematic study of the impact of adding amphiphilic triblock copolymers to water-in-perfluorocarbon nanoemulsions on their structure and viscoelasticity, utilizing small-angle neutron and X-ray scattering (SANS and SAXS) and rheology. We find that an intermediate concentration of copolymer yields the highest strength of attraction between droplets, corresponding to a maximum in the elasticity and storage modulus. The stability and viscoelastic moduli can be tuned via the amount of copolymer and surfactant along with the volume fraction of aqueous phase. SANS provides the detail on nanostructure and can be fit to a spherical core-shell form factor with a square-well hard sphere structure factor. The PFC nanoemulsion system displays thermoresponsive and thermoreversible properties in temperature sweeps.