Hybrid Crosslinked Methylcellulose Hydrogel: A Predictable and Tunable Platform for Local Drug Delivery

Study of factors affecting cellulose derivatives composite in anticancer drug delivery: A comprehensive review

The targeted distribution of therapeutic molecules in cancer cells poses several challenges for biomedical applications. Drug delivery systems (DDS) are primarily designed to target cancer cells effectively to achieve maximum therapeutic effects. Cellulose is a well-known organic molecule owing to its biodegradability, biocompatibility, low toxicity, prolonged stability, and superior loading characteristics. However, cellulose composites have faced numerous drawbacks, such as higher molecular size, non-covalent interactions, poor mechanical strength, and limited water solubility. In contrast, cellulose derivatization has enhanced drug loading and release efficiency, improved mechanical strength, and mitigated drug solubility issues. This review summarized the recent advancement in cellulose-based composites such as DDS for cancer cell treatment and discussed responsive factors. The pH, temperature, magnetic nanoparticles, solubility, porosity, mechanical strength, nanoparticle size, increased time of drug release, crosslinking efficiency, etc., are major responsive assays that influence the therapeutic potential of anticancer drugs. Furthermore, overviewed the cellulose nanoformulations in sustained anticancer drug release and successfully illustrated the synthesizing methodologies as well as challenges in efficient DDS applications. Moreover, a brief overview of the interdisciplinary industrial uses of cellulose composites, including paper, textiles, and nanotechnology, is presented. Finally, cellulose-based composites provide a novel way of producing excellent DDS with enhanced therapeutic properties.

Functionalized amino acid-based injectable hydrogels for sustained drug delivery

Drug delivery vehicles optimize therapeutic outcomes by enhancing drug efficacy, minimizing side effects, and providing controlled release. Injectable hydrogels supersede conventional ones in the field of drug delivery owing to their less invasive administration and improved targeting. However, they face challenges such as low biodegradability and biocompatibility, potentially compromising their effectiveness. To address these limitations, a modified amino acid-based pH-responsive injectable shear-thinning hydrogel cl-β-CD-g-p(Gly-MA) has been developed as an efficient drug carrier. In the two-step synthetic approaches, first, the well-known amino acid glycine (Gly) is modified to form glycine methacrylate (Gly-MA). Afterward, Gly-MA is chemically crosslinked with β-cyclodextrin (β-CD), an oligosaccharide, using an ethylene glycol dimethacrylate (EGDMA) crosslinker. The presence of these biomaterials as building blocks enhances the biocompatibility, hemocompatibility, and biodegradability of the hydrogel. They also reduce the risk of immunogenicity. The unique property of easy injectability enables minimally invasive administration. This feature also helps prolong drug retention at the target site, further optimizing drug delivery efficiency. Moreover, the pH-responsive feature of the developed cl-β-CD-g-p(Gly-MA) hydrogel ensures controlled drug release in response to the physiological conditions of the target site, enhancing therapeutic efficacy. The study focuses on investigating the in vitro loading and release of diclofenac sodium (DS), a non-steroidal anti-inflammatory drug (NSAID) commonly used to treat arthritic pain and inflammation.

Microenvironment Self-Adaptive Nanomedicine Promotes Spinal Cord Repair by Suppressing Inflammation Cascade and Neural Apoptosis

Despite various biomaterial-based strategies are tried in spinal cord injury (SCI), developing safe and effective microinvasive pharmacotherapy strategies is still an unmet clinical need. Stimuli-responsive nanomedicine has emerged as a promising non-invasion technology, which enhances drug delivery and promotes functional recovery following SCI. Considering the multiple progressive pathological events and the blood spinal cord barrier (BSCB) associating SCI, a microenvironment self-adaptive nanoparticle (custom-designed with rabies virus glycoprotein 29-RVG29 and hyaluronic acid-HA, RHNP) capable of consistently crossing the BSCB and selectively targeting inflammatory cells and neural cells based on different stages of SCI are developed. The data indicated that RHNP can effectively traverse the BSCB through RVG29, and adaptively modulate cellular internalization by selectively exposing either HA or RVG29 through diselenide bonds, depending on pathological reactive oxygen species (ROS) signals. Furthermore, curcumin is loaded into RHNP (RHNP-Cur) to improve motor function and coordination of hind-limbs in a traumatic SCI mouse model. This study finds that RHNP-Cur exhibited inhibitory effects on the inflammatory cascade originating from M1 microglia/macrophages and neurotoxic astrocytes, and protected neural cells from inflammation-induced apoptosis during nerve regeneration. Collectively, the work provides a microenvironment self-adaptive nanomedicine which enables efficient microinvasive treatment of SCI.

Regenerative medicine approaches for the treatment of spinal cord injuries: Progress and challenges

Spinal cord injury (SCI) is a profound medical condition that significantly hampers motor function, imposing substantial limitations on daily activities and exerting a considerable financial burden on patients and their families. The constrained regenerative capacity of endogenous spinal cord tissue, exacerbated by the inflammatory response following the initial trauma, poses a formidable obstacle to effective therapy. Recent advancements in the field, stem cells, biomaterials, and molecular therapy, show promising outcomes. This review provides a comprehensive analysis of tissue engineering and regenerative medicine approaches for SCI treatment, including cell transplantation, tissue-engineered construct implantation, and other potential therapeutic strategies. Additionally, it sheds light on preclinical animal studies and recent clinical trials incorporating these modalities, providing a glimpse into the evolving landscape of SCI management. STATEMENT OF SIGNIFICANCE: The investigation into spinal cord injury (SCI) treatments focuses on reducing long-term impacts by targeting scar inhibition and enhancing regeneration through stem cells, with or without growth factors. Induced pluripotent stem cells (iPSCs) show promise for autologous use, with clinical trials confirming their safety. Challenges include low cell viability and difficulty in targeted differentiation. Biomaterial scaffolds hold potential for improving cell viability and integration, and extracellular vesicles (EVs) are emerging as a novel therapy. While EV research is in its early stages, stem cell trials demonstrate safety and potential recovery. Advancing tissue engineering approaches with biomaterial scaffolds is crucial for human trials.

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.

Dimethyl Fumarate-Loaded Gellan Gum Hydrogels Can Reduce In Vitro Chemokine Expression in Oral Cells

Dimethyl fumarate (DMF), originally proposed to treat multiple sclerosis, is considered to have a spectrum of anti-inflammatory effects that effectively control periodontitis, mainly when applied with a hydrogel delivery system. Chemokine expression by gingival fibroblasts is a significant driver of periodontitis; thus, hydrogel-based strategies to deliver DMF, which in turn dampen chemokine expression, are of potential clinical relevance. To test this approach, we have established a bioassay where chemokine expression is induced by exposing gingival fibroblast to IL1β and TNFα, or with saliva. We show herein that DMF effectively reduced the expression of CXCL8, CXCL1, CXCL2, and CCL2-and lowered the phosphorylation of ERK and JNK-without affecting cell viability. This observation was confirmed by immunoassays with CXCL8. Consistently, the forced chemokine expression in HSC2 oral squamous epithelial cells was greatly diminished by DMF. To implement our hydrogel-based delivery system, gingival fibroblasts were cocultured with gellan gum hydrogels enriched for DMF. In support of our strategy, DMF-enriched gellan gum hydrogels significantly reduced the forced chemokine expression in gingival fibroblasts. Our data suggest that DMF exerts its anti-inflammatory activity in periodontal cells when released from gellan gum hydrogels, suggesting a potential clinical relevance to control overshooting chemokine expression under chronic inflammatory conditions.

Recent advances on thermosensitive hydrogels-mediated precision therapy

Precision therapy has become the preferred choice attributed to the optimal drug concentration in target sites, increased therapeutic efficacy, and reduced adverse effects. Over the past few years, sprayable or injectable thermosensitive hydrogels have exhibited high therapeutic potential. These can be applied as cell-growing scaffolds or drug-releasing reservoirs by simply mixing in a free-flowing sol phase at room temperature. Inspired by their unique properties, thermosensitive hydrogels have been widely applied as drug delivery and treatment platforms for precision medicine. In this review, the state-of-the-art developments in thermosensitive hydrogels for precision therapy are investigated, which covers from the thermo-gelling mechanisms and main components to biomedical applications, including wound healing, anti-tumor activity, osteogenesis, and periodontal, sinonasal and ophthalmic diseases. The most promising applications and trends of thermosensitive hydrogels for precision therapy are also discussed in light of their unique features.

Chemical and Photochemical-Driven Dissipative Fe3+/Fe2+-Ion Cross-Linked Carboxymethyl Cellulose Gels Operating Under Aerobic Conditions: Applications for Transient Controlled Release and Mechanical Actuation

A Fe3+-ion cross-linked carboxymethyl cellulose, Fe3+-CMC, redox-active gel exhibiting dissipative, transient stiffness properties is introduced. Chemical or photosensitized reduction of the higher-stiffness Fe3+-CMC to the lower-stiffness Fe2+-CMC gel, accompanied by the aerobic reoxidation of the Fe2+-CMC matrix, leads to the dissipative, transient stiffness, functional matrix. The light-induced, temporal, transient release of a load (Texas red dextran) and the light-triggered, transient mechanical bending of a poly-N-isopropylacrylamide (p-NIPAM)/Fe3+-CMC bilayer construct are introduced, thus demonstrating the potential use of the dissipative Fe3+-CMC gel for controlled drug release or soft robotic applications.

Understanding Self-Assembly and Molecular Packing in Methylcellulose Aqueous Solutions Using Multiscale Modeling and Simulations

We present a multiscale molecular dynamics (MD) simulation study on self-assembly in methylcellulose (MC) aqueous solutions. First, using MD simulations with a new coarse-grained (CG) model of MC chains in implicit water, we establish how the MC chains self-assemble to form fibrils and fibrillar networks and elucidate the MC chains' packing within the assembled fibrils. The CG model for MC is extended from a previously developed model for unsubstituted cellulose and captures the directionality of H-bonding interactions between the -OH groups. The choice and placement of the CG beads within each monomer facilitates explicit modeling of the exact degree and position of methoxy substitutions in the monomers along the MC chain. CG MD simulations show that with increasing hydrophobic effect and/or increasing H-bonding strength, the commercial MC chains (with degree of methoxy substitution, DS, ∼1.8) assemble from a random dispersed configuration into fibrils. The assembled fibrils exhibit consistent fibril diameters regardless of the molecular weight and concentration of MC chains, in agreement with past experiments. Most MC chains' axes are aligned with the fibril axis, and some MC chains exhibit twisted conformations in the fibril. To understand the molecular driving force for the twist, we conduct atomistic simulations of MC chains preassembled in fibrils (without any chain twists) in explicit water at 300 and 348 K. These atomistic simulations also show that at DS = 1.8, MC chains adopt twisted conformations, with these twists being more prominent at higher temperatures, likely as a result of shielding of hydrophobic methyl groups from water. For MC chains with varying DS, at 348 K, atomistic simulations show a nonmonotonic effect of DS on water-monomer contacts. For 0.0 < DS < 0.6, the MC monomers have more water contacts than at DS = 0.0 or DS > 0.6, suggesting that with few methoxy substitutions, the MC chains are effectively hydrophilic, letting the water molecules diffuse into the fibril to participate in H-bonds with the MC chains' remaining -OH groups. At DS > 0.6, the MC monomers become increasingly hydrophobic, as seen by decreasing water contacts around each monomer. We conclude based on the atomistic observations that MC chains with lower degrees of substitutions (DS ≤ 0.6) should exhibit solubility in water over broader temperature ranges than DS ∼ 1.8 chains.

Statistical optimization of hydrazone-crosslinked hyaluronic acid hydrogels for protein delivery

Hydrazone-crosslinked hydrogels are attractive protein delivery vehicles for regenerative medicine. However, each regenerative medicine application requires unique hydrogel properties to achieve an ideal outcome. The properties of a hydrogel can be impacted by numerous factors involved in its fabrication. We used design of experiments (DoE) statistical modeling to efficiently optimize the physicochemical properties of a hyaluronic acid (HA) hydrazone-crosslinked hydrogel for protein delivery for bone regeneration. We modified HA with either adipic acid dihydrazide (HA-ADH) or aldehyde (HA-Ox) functional groups and used DoE to evaluate the interactions of three input variables, the molecular weight of HA (40 or 100 kDa), the concentration of HA-ADH (1-3% w/v), and the concentration of HA-Ox (1-3% w/v), on three output responses, gelation time, compressive modulus, and hydrogel stability over time. We identified 100 kDa HA-ADH3.00HA-Ox2.33 as an optimal hydrogel that met all of our design criteria, including displaying a gelation time of 3.7 minutes, compressive modulus of 62.1 Pa, and minimal mass change over 28 days. For protein delivery, we conjugated affinity proteins called affibodies that were specific to the osteogenic protein bone morphogenetic protein-2 (BMP-2) to HA hydrogels and demonstrated that our platform could control the release of BMP-2 over 28 days. Ultimately, our approach demonstrates the utility of DoE for optimizing hydrazone-crosslinked HA hydrogels for protein delivery.

Chondroitinase as a therapeutic enzyme: Prospects and challenges

The chondroitinases (Chase) are bacterial lyases that specifically digest chondroitin sulfate and/or dermatan sulfate glycosaminoglycans via a β-elimination reaction and generate unsaturated disaccharides. In recent decades, these enzymes have attracted the attention of many researchers due to their potential applications in various aspects of medicine from the treatment of spinal cord injury to use as an analytical tool. In spite of this diverse spectrum, the application of Chase is faced with several limitations and challenges such as thermal instability and lack of a suitable delivery system. In the current review, we address potential therapeutic applications of Chase with emphasis on the challenges ahead. Then, we summarize the latest achievements to overcome the problems by considering the studies carried out in the field of enzyme engineering, drug delivery, and combination-based therapy.

Crosslinking strategies in modulating methylcellulose hydrogel properties

Methylcellulose (MC) hydrogels are ideal materials for the design of thermo-responsive platforms capable of exploiting the environment temperature as a driving force to activate their smart transition. However, MC hydrogels usually show reduced stability in an aqueous environment and low mechanical properties, limiting their applications' breadth. A possible approach intended to overcome these limitations is chemical crosslinking, which represents a simple yet effective strategy to modify the MC hydrogels' properties (e.g., physicochemical, mechanical, and biological). In this regard, understanding the selected crosslinking method's role in modulating the MC hydrogels' properties is a key factor in their design. This review offers a perspective on the main MC chemical crosslinking approaches reported in the literature. Three main categories can be distinguished: (i) small molecule crosslinkers, (ii) crosslinking by high-energy radiation, and (iii) crosslinking via MC chemical modification. The advantages and limitations of each approach are elucidated, and special consideration is paid to the thermo-responsive properties after crosslinking towards the development of MC hydrogels with enhanced physical stability and mechanical performance, preserving the thermo-responsive behavior.

Double-Cross-Linked Hydrogel with Long-Lasting Underwater Adhesion: Enhancement of Maxillofacial In Situ and Onlay Bone Retention

Bone retention is a usual clinical problem existing in a lot of maxillofacial surgeries involving bone reconstruction and bone transplantation, which puts forward the requirements for bone adhesives that are stable, durable, biosafe, and biodegradable in wet environment. To relieve the suffering of patients during maxillofacial surgery with one-step operation and satisfying repair, herein, we developed a double-cross-linked A-O hydrogel named by its two components: [(3-Aminopropyl) methacrylamide]-co-{[Tris(hydroxymethyl) methyl] acrylamide} and oxidated methylcellulose. With excellent bone adhesion ability, it can maintain long-lasting stable underwater bone adhesion for over 14 days, holding a maximum adhesion strength of 2.32 MPa. Schiff-base reaction and high-density hydrogen bonds endow the hydrogel with strong cohesion and adhesion performance as well as maneuverable properties such as easy formation and injectability. A-O hydrogel not only presents rarely reported long-lasting underwater adhesion of hard tissue but also owns inherent biocompatibility and biodegradation properties with a porous structure that facilitates the survival of bone graft. Compared to the commercial cyanoacrylate adhesive (3 M Vetbond Tissue Adhesive), the A-O hydrogel is confirmed to be safer, more stable, and more effective in calvarial in situ bone retention model and onlay bone retention model of rat, providing a practical solution for the everyday scenario of clinical bone retention.

Injectable hydrogels for cartilage and bone tissue regeneration: A review

Annually, millions of patients suffer from irreversible injury owing to the loss or failure of an organ or tissue caused by accident, aging, or disease. The combination of injectable hydrogels and the science of stem cells have emerged to address this persistent issue in society by generating minimally invasive treatments to augment tissue function. Hydrogels are composed of a cross-linked network of polymers that exhibit a high-water retention capacity, thereby mimicking the wet environment of native cells. Due to their inherent mechanical softness, hydrogels can be used as needle-injectable stem cell carrier materials to mend tissue defects. Hydrogels are made of different natural or synthetic polymers, displaying a broad portfolio of eligible properties, which include biocompatibility, low cytotoxicity, shear-thinning properties as well as tunable biological and physicochemical properties. Presently, novel ongoing developments and native-like hydrogels are increasingly being used broadly to improve the quality of life of those with disabling tissue-related diseases. The present review outlines various future and in-vitro applications of injectable hydrogel-based biomaterials, focusing on the newest ongoing developments of in-situ forming injectable hydrogels for bone and cartilage tissue engineering purposes.

Supramolecular nanoarchitectonics of phenolic-based nanofiller for controlled diffusion of versatile drugs in hydrogels

Drug-dependent design of hydrogels is currently required for engineering the controlled release of therapeutics, which is a major contributor to the technical challenges relating to the clinical translation of hydrogel-drug systems. Herein, by integrating supramolecular phenolic-based nanofillers (SPFs) into hydrogel microstructures we developed a facile strategy to endow a range of clinically relevant hydrogels with controlled release properties for diverse therapeutic agents. The assembly of multiscale SPF aggregates leads to tunable mesh size and multiple dynamic interactions between SPF aggregates and drugs, which relaxes the available choices of drugs and hydrogels. This simple approach allowed for the controlled release of 12 representative drugs evaluated with 8 commonly used hydrogels. Moreover, the anesthetic drug lidocaine was loaded into SPF-integrated alginate hydrogel and demonstrated sustained release for 14 days in vivo, validating the potential for long-term anesthesia in patients.

Eco-Friendly Methods for Extraction and Modification of Cellulose: An Overview

Cellulose is the most abundant renewable polymer on Earth and can be obtained from several different sources, such as trees, grass, or biomass residues. However, one of the issues is that not all the fractionation processes are eco-friendly and are essentially based on cooking the lignocellulose feedstock in a harsh chemical mixture, such as NaOH + Na₂S, and water, to break loose fibers. In the last few years, new sustainable fractionation processes have been developed that enable the obtaining of cellulose fibers in a more eco-friendly way. As a raw material, cellulose's use is widely known and established in many areas. Additionally, its products/derivatives are recognized to have a far better environmental impact than fossil-based materials. Examples are textiles and packaging, where forest-based fibers may contribute to renewable and biodegradable substitutes for common synthetic materials and plastics. In this review, some of the main structural characteristics and properties of cellulose, recent green extraction methods/strategies, chemical modification, and applications of cellulose derivatives are discussed.

Wetting-Enabled Three-Dimensional Interfacial Polymerization (WET-DIP) for Bioinspired Anti-Dehydration Hydrogels

Anti-dehydration hydrogels have attracted considerable attention due to their promising applications in stretchable sensors, flexible electronics, and soft robots. However, anti-dehydration hydrogels prepared by conventional strategies inevitably depend on additional chemicals or suffer from cumbersome preparation processes. Here, inspired by the succulent Fenestraria aurantiaca a one-step wetting-enabled three-dimensional interfacial polymerization (WET-DIP) strategy for constructing organogel-sealed anti-dehydration hydrogels is developed. By virtue of the preferential wetting on the hydrophobic-oleophilic substrate surfaces, the organogel precursor solution can spread on the three-dimensional (3D) surface and encapsulate the hydrogel precursor solution, forming anti-dehydration hydrogel with 3D shape after in situ interfacial polymerization. The WET-DIP strategy is simple and ingenious, and accessible to discretionary 3D-shaped anti-dehydration hydrogels with a controllable thickness of the organogel outer layer. Strain sensors based on this anti-dehydration hydrogel also exhibit long-term stability in signal monitoring. This WET-DIP strategy shows great potentialities for constructing hydrogel-based devices with long-term stability.

Switchable and dynamic G-quadruplexes and their applications

G-Quadruplexes attract growing interest as functional constituents in biology, chemistry, nanotechnology, and material science. In particular, the reversible dynamic reconfiguration of G-quadruplexes provides versatile means to switch DNA nanostructures, reversibly control catalytic functions of DNA assemblies, and switch material properties and functions. The present review article discusses the switchable dynamic reconfiguration of G-quadruplexes as central functional and structural motifs that enable diverse applications in DNA nanotechnology and material science. The dynamic reconfiguration of G-quadruplexes has a major impact on the development of DNA switches and DNA machines. The integration of G-quadruplexes with enzymes yields supramolecular assemblies exhibiting switchable catalytic functions guided by dynamic G-quadruplex topologies. In addition, G-quadruplexes act as important building blocks to operate constitutional dynamic networks and transient dissipative networks mimicking complex biological dynamic circuitries. Furthermore, the integration of G-quadruplexes with DNA nanostructures, such as origami tiles, introduces dynamic and mechanical features into these static frameworks. Beyond the dynamic operation of G-quadruplex structures in solution, the assembly of G-quadruplexes on bulk surfaces such as electrodes or nanoparticles provides versatile means to engineer diverse electrochemical and photoelectrochemical devices and to switch the dynamic aggregation/deaggregation of nanoparticles, leading to nanoparticle assemblies that reveal switchable optical properties. Finally, the functionalization of hydrogels, hydrogel microcapsules, or nanoparticle carriers, such as SiO₂ nanoparticles or metal-organic framework nanoparticles, yields stimuli-responsive materials exhibiting shape-memory, self-healing, and controlled drug release properties. Indeed, G-quadruplex-modified nanomaterials find growing interest in the area of nanomedicine. Beyond the impressive G-quadruplex-based scientific advances achieved to date, exciting future developments are still anticipated. The review addresses these goals by identifying the potential opportunities and challenges ahead of the field in the coming years.

Recent Advances in Cell and Functional Biomaterial Treatment for Spinal Cord Injury

Spinal cord injury (SCI) is a devastating central nervous system disease caused by accidental events, resulting in loss of sensory and motor function. Considering the multiple effects of primary and secondary injuries after spinal cord injury, including oxidative stress, tissue apoptosis, inflammatory response, and neuronal autophagy, it is crucial to understand the underlying pathophysiological mechanisms, local microenvironment changes, and neural tissue functional recovery for preparing novel treatment strategies. Treatment based on cell transplantation has become the forefront of spinal cord injury therapy. The transplanted cells provide physical and nutritional support for the damaged tissue. At the same time, the implantation of biomaterials with specific biological functions at the site of the SCI has also been proved to improve the local inhibitory microenvironment and promote axonal regeneration, etc. The combined transplantation of cells and functional biomaterials for SCI treatment can result in greater neuroprotective and regenerative effects by regulating cell differentiation, enhancing cell survival, and providing physical and directional support for axon regeneration and neural circuit remodeling. This article reviews the pathophysiology of the spinal cord, changes in the microenvironment after injury, and the mechanisms and strategies for spinal cord regeneration and repair. The article will focus on summarizing and discussing the latest intervention models based on cell and functional biomaterial transplantation and the latest progress in combinational therapies in SCI repair. Finally, we propose the future prospects and challenges of current treatment regimens for SCI repair, to provide references for scientists and clinicians to seek better SCI repair strategies in the future.

Injectable light-assisted thermo-responsive methylcellulose-sodium humate hydrogel proposed for photothermal ablation and localized delivery of cisplatin

This study aimed to develop injectable light-assisted thermo-responsive methylcellulose hydrogels filled with sodium humate, which were proposed for photothermal ablation and localized cisplatin delivery. Sodium humate converts light energy from laser beams into thermal energy, which causes methylcellulose to gel, thereby controlling the release of chemotherapy agents. Meanwhile, light emission causes to the photothermal ablation of tumor cells. For determining the optimal production conditions, different concentrations of sodium humate and light emission times were investigated. Results show that hydrogel uniformity is highly dependent on variables. An increase in sodium humate concentration and emission time resulted in a slight reduction in swelling ratio and an increase in durability. According to the simulation conditions, the cisplatin release profile was consistent with a non-Fickian mechanism with a predominant erosion contribution. In conjugation with increasing light emission time and sodium humate content, the storage modulus and viscosity increased, demonstrating hydrogel’s sol-gel transition and long-lasting durability. The intrinsic fluorescence spectroscopy study revealed that the hydrogel-model protein complex empowered hydrogel bio-performance. Laser emission and cisplatin release synergistically reduced the number of viable osteosarcoma cell lines, suggesting the possibility of tumor ablation. This study describes the potential of simultaneous photothermal therapy and chemotherapy in osteosarcoma treatment, laying the groundwork for future preclinical and clinical trials.

3D Printing Methyl Cellulose Hydrogel Wound Dressings with Parameter Exploration Via Computational Fluid Dynamics Simulation

PURPOSE

To investigate and optimize the use of methyl cellulose in the fabrication of three-dimensional (3D) printed drug-loaded hydrogel wound dressings for the treatment of burns.

METHOD

The effects of incorporating various salts on the properties of methyl cellulose, especially the gelation temperature was investigated for methyl cellulose to undergo gelation at skin temperature (i.e., 31.7°C). The optimized methyl cellulose and salt compositions were then loaded with various drugs beneficial for the treatment of burns. Printability and cumulative release profiles for selected drugs were then obtained, which were then fitted to common release kinetic models. Computational Fluid Dynamics (CFD) simulation was also explored to investigate the relationship between printing parameters and the hydrogel filament produced during extrusion.

RESULTS

The printed hydrogels had moderate dimensional integrity, were found to be stable for up to 2 weeks and demonstrated good swelling properties. In vitro drug release studies of various drugs showed that the hydrogel was able to release various drugs within 6 h and release profiles were fitted to common in vitro drug release models, such as the Korsmeyer Peppas model and the Weibull model. While there were deviations from the actual printing process, CFD simulation was able to predict the shape of the printed structure and showed fair accuracy in determining the mass flow rate and line width of extruded hydrogels.

CONCLUSIONS

Methyl cellulose hydrogels with optimized salt composition demonstrated suitable properties for a wound dressing application, revealing its potential to be used for in situ wound dressing applications.

Local delivery of biocompatible lentinan/chitosan composite for prolonged inhibition of postoperative breast cancer recurrence

Postsurgical localized chemotherapy for breast cancer recurrence (BCR) still faces many problems which dampen researchers' enthusiasm and discounted prognosis. Simple strategies with controllable toxicities are expected to address these hurdles. Lentinan (LNT) has excellent biocompatibility and notable antitumor activity but rather low bioavailability after intravenous or oral administration. Here, a sponge-like LNT/chitosan composite (LNT/CS sponge) was prepared for efficient local delivery to prevent postoperative BCR. The obtained sponges exhibit uniform porosity and sustained release of LNT in vitro and in vivo. Furthermore, the sponges were implanted and showed significant reduction of postsurgical recurrence and suppression of long-term tumor regrowth with favorable biocompatibility in a subcutaneous postsurgical recurrence mouse model. Subsequent studies revealed that LNT can restrain the stemness of breast cancer cells, which may account for the long-term inhibition of tumor relapse. Therefore, LNT/CS sponge has a great potential as a promising alternative for postsurgical BCR.

Synthesis of an Enzyme-Mediated Reversible Cross-linked Hydrogel for Cell Culture

Detachment of fragile cell types cultured on two-dimensional (2D) surfaces has been shown to be detrimental to their viability. For example, detachment of induced pluripotent stem cell (iPSC)-derived neurons grown in vitro in 2D typically results in loss of neuronal connections and/or cell death. Avoiding cell detachment altogether by changing the properties of the substrate on which the cells are grown is a compelling strategy to maintain cell viability. Here, we present the synthesis of a reversible cross-linked hydrogel that is sufficiently stable for cell culture and differentiation and is cleaved by an external stimulus, facilitating injection. Specifically, hyaluronan (HA) and methylcellulose (MC) were modified with ketone and aldehyde groups, respectively, and a TEV protease-degradable peptide was synthesized via solid-state synthesis and modified at both termini with oxyamine groups to cross-link HA-ketone and MC-aldehyde to produce oxime-cross-linked HA × MC. The HA × MC hydrogel demonstrated good stability, enzyme-sensitive degradation, and cytocompatibility with iPSC-derived neural progenitor cells, laying the framework for broad applicability.

Near-infrared light-responsive hybrid hydrogels for the synergistic chemo-photothermal therapy of oral cancer

Light-stimulus-responsive therapies have been recognized as a promising strategy for the efficient and safe treatment of oral squamous cell carcinoma (OSCC). Hydrogels have emerged as a promising multifunctional platform combining localized drug delivery and sustained drug release with multimodal properties for combined OSCC therapy. However, inaccurate drug release and limited light-absorption efficiency have hindered their on-demand chemo-photothermal applications. To tackle these problems, an injectable and near-infrared (NIR) light-responsive hybrid system was developed by incorporating light-responsive mesoporous silica nanoparticles (MSNs) as doxorubicin (DOX) carriers into the IR820/methylcellulose hydrogel networks for chemophotothermal therapy. Under NIR radiation, the incorporated IR820, a new green cyanine dye, was excited to induce photothermal effects against tumor cells. Meanwhile, MSNs achieved self-degradation-controlled DOX release via the cleavage of diselenide bonds induced by reactive oxygen species. Through the combination of chemotherapy and phototherapy, a long-lasting synergistic anti-tumor effect was achieved in vitro and in vivo with less toxicity. These findings demonstrate the potential of light-responsive hydrogels as a multifunctional platform for accurate synergistic chemophotothermal treatment of OSCC.

Instant hydrogelation encapsulates drugs onto implants intraoperatively against osteoarticular tuberculosis

Osteoarticular Tuberculosis (TB) is a challenging issue because of its chronicity and recurrence. Many drug delivery systems (DDSs) have been developed for general chemotherapy. Herein, we take advantage of instant hydrogelation to in situ encapsulate drugs onto implants intraoperatively, optimizing the drug release profile against osteoarticular TB. First-line chemodrugs, i.e. rifampicin (RFP) and isoniazid (INH) are firstly loaded on tricalcium phosphate (TCP). Then, the encapsulating hydrogel is fabricated by dipping in chitosan (CS) and β-glycerophosphate (β-GP) solution and heating at 80 °C for 40 min. The hydrogel encapsulation inhibits explosive drug release initially, but maintains long-term drug release (INH, 158 days; RFP, 53 days) in vitro. Therefore, this technique could inhibit bone destruction and inflammation from TB effectively in vivo, better than our previous ex situ prepared DDSs. The encapsulating technology, i.e. instant hydrogelation of drug-loaded implants, shows potential for regulating the type and ratio of drugs, elastic and viscous modulus of the hydrogel according to the state of illness intraoperatively for optimal drug release.

Norbornene-functionalized methylcellulose as a thermo- and photo-responsive bioink

Three-dimensional (3D) bioprinting has emerged as an important tool to fabricate scaffolds with complex structures for tissue engineering and regenerative medicine applications. For extrusion-based 3D bioprinting, the success of printing complex structures relies largely on the properties of bioink. Methylcellulose (MC) has been exploited as a potential bioink for 3D bioprinting due to its temperature-dependent rheological properties. However, MC is highly soluble and has low structural stability at room temperature, making it suboptimal for 3D bioprinting applications. In this study, we report a one-step synthesis protocol for modifying MC with norbornene (MCNB), which serves as a new bioink for 3D bioprinting. MCNB preserves the temperature-dependent reversible sol-gel transition and readily reacts with thiol-bearing linkers through light-mediated step-growth thiol-norbornene photopolymerization. Furthermore, we rendered the otherwise inert MC network bioactive through facile conjugation of integrin-binding ligands (e.g. CRGDS) or via incorporating cell-adhesive and protease-sensitive gelatin-based macromer (e.g. GelNB). The adaptability of the new MCNB-based bioink offers an attractive option for diverse 3D bioprinting applications.

Facile Construction of a Solely-DNA-Based System for Targeted Delivery of Nucleic Acids

We designed a functional drug delivery system based solely on DNA. The whole system was built with only four DNA strands. Cyclization of DNA strands excluded the formation of byproducts. DNA aptamers were equipped to endow triangular DNA nanostructures with targeting ability. The homogeneity of materials enabled not only facile construction but also convenient loading of nucleic acid-based drugs with much ease.

Curcumin-Microsphere/IR820 Hybrid Bifunctional Hydrogels for In Situ Osteosarcoma Chemo-co-Thermal Therapy and Bone Reconstruction

Conventional biomaterial-mediated osteosarcoma therapy mainly focuses on its antitumor effect yet often fails to overcome the problem of post-treatment bone tissue defect repair. Simultaneously, minimally invasive drug delivery methods are becoming spotlights for normal tissue preservation. Herein, an injectable curcumin-microsphere/IR820 coloaded hybrid methylcellulose hydrogel (Cur-MP/IR820 gel) platform was designed for osteosarcoma therapy and bone regeneration. In vitro, the K7M2wt osteosarcoma cells were eradicated by hyperthermia and curcumin. Later, the sustained release of curcumin promoted alkaline phosphatase expression and calcium deposition of bone mesenchymal stem cells. In vivo, this hybrid hydrogel could reach tumor site via injection and turned into hydrogel due to heat sensitivity. Under the irradiation of an 808 nm laser, localized hyperthermia (∼51 °C) generated in 5 min to ablate the tumor. Meanwhile, the thermal-accelerated curcumin release and thermal-increased cell membrane permeability led to tumor cell apoptosis. Tumors in photothermal-co-chemotherapy group were successfully restrained from day 2 after treatment. After that, bone reconstruction was promoted because of sustained released curcumin. The chemo-co-thermal efficacy and osteogenic capacity of Cur-MP/IR820 hydrogel suggest a promising approach to the treatment of osteosarcoma and provide provoking inspiration for treating bone tumors and repairing bone tissue.

3D-printed construct from hybrid suspension as spatially and temporally controlled protein delivery system

Protein delivery systems have been extensively applied in controlled releasing of protein or polypeptides for therapeutic treatment or tissue regeneration. While 3 D printing technology shows great promise in novel dosage form with tailoring dose size and drug release profile, 3 D printable protein delivery system has to face many difficult challenges. In this study, we developed a hybrid suspension combining Eudragit polyacrylate colloid as matrix material and Pluronic polyether hydrogel as diffusion channel for protein release. This hybrid suspension can be 3 D-printed into construct with complex shape and inner structures thanks to its pseudoplastic and thixotropic rheological properties. The protein can be incorporated in hybrid suspension either in its original or nanoparticle capsulated form. The experiment shows that the protein release from construct is a function of drying time, molecular weight (MW) of chitosan, as well as their own structural/diffusional properties. Also, the theoretical derivation suggests polyacrylate matrix tortuosity, chitosan erosion rate as well as hydrogel diffusion coefficient all contributed to the extended duration of release profile. In addition, cytotoxicity test through cell culture confirmed that the construct fabricated from hybrid suspension exhibit relative good bio-compatibility. Finally, heterogeneous constructs with zoned design were fabricated as protein delivery system, which demonstrated the capability of hybrid suspension technique for spatial and temporal release of macromolecular drugs to realize pharmaceutical effectiveness or guild cell organization.

Biomaterials for protein delivery for complex tissue healing responses

Tissue repair requires a complex cascade of events mediated by a variety of cells, proteins, and matrix molecules; however, the healing cascade can be easily disrupted by numerous factors, resulting in impaired tissue regeneration. Recent advances in biomaterials for tissue regeneration have increased the ability to tailor the delivery of proteins and other biomolecules to injury sites to restore normal healing cascades and stimulate robust tissue repair. In this review, we discuss the evolution of the field toward creating biomaterials that precisely control protein delivery to stimulate tissue regeneration, with a focus on addressing complex and dynamic injury environments. We highlight biomaterials that leverage different mechanisms to deliver and present proteins involved in healing cascades, tissue targeting and mimicking strategies, materials that can be triggered by environmental cues, and integrated strategies that combine multiple biomaterial properties to improve protein delivery. Improvements in biomaterial design to address complex injury environments will expand our understanding of both normal and aberrant tissue repair processes and ultimately provide a better standard of patient care.

Sulfonated cryogel scaffolds for focal delivery in ex-vivo brain tissue cultures

The human brain has unique features that are difficult to study in animal models, including the mechanisms underlying neurodevelopmental and psychiatric disorders. Despite recent advances in human primary brain tissue culture systems, the use of these models to elucidate cellular disease mechanisms remains limited. A major reason for this is the lack of tools available to precisely manipulate a specific area of the tissue in a reproducible manner. Here we report an easy-to-use tool for site-specific manipulation of human brain tissue in culture. We show that line-shaped cryogel scaffolds synthesized with precise microscale dimensions allow the targeted delivery of a reagent to a specific region of human brain tissue in culture. 3-sulfopropyl acrylate (SPA) was incorporated into the cryogel network to yield a negative surface charge for the reversible binding of molecular cargo. The fluorescent dyes BODIPY and DiI were used as model cargos to show that placement of dye loaded scaffolds onto brain tissue in culture resulted in controlled delivery without a burst release, and labelling of specific regions without tissue damage. We further show that cryogels can deliver tetrodotoxin to tissue, inhibiting neuronal function in a reversible manner. The robust nature and precise dimensions of the cryogel resulted in a user-friendly and reproducible tool to manipulate primary human tissue cultures. These easy-to-use cryogels offer an innovate approach for more complex manipulations of ex-vivo tissue.

Immunomodulatory Layered Double Hydroxide Nanoparticles Enable Neurogenesis by Targeting Transforming Growth Factor-β Receptor 2

Immune microenvironment amelioration and reconstruction by functional biomaterials has become a promising strategy for spinal cord injury (SCI) recovery. In this study, we evaluated the neural regeneration and immunoregulation functions of Mg/Al layered double hydroxide (Mg/Al-LDH) nanoparticles in completely transected and excised mice and revealed the immune-related mechanisms. LDH achieved significant performance in accelerating neural stem cells (NSCs) migration, neural differentiation, L-Ca²⁺ channel activation, and inducible action potential generation. In vivo, the behavioral and electrophysiological performance of SCI mice was significantly improved by LDH implantation, with BrdU⁺ endogenous NSCs and neurons clearly observed in the lesion sites. According to RNA-seq and ingenuity pathway analysis, transforming growth factor-β receptor 2 (TGFBR2) is the key gene through which LDH inhibits inflammatory responses and accelerates neural regeneration. Significant colocalization of TGFBR2 and LDH was found on the cell membranes of NSCs both in vitro and in vivo, and LDH increased the expression of TGF-β2 in NSCs and activated the proliferation of precursor neural cells. LDH decreased the expression of M1 markers and increased the expression of M2 markers in both microglia and bone marrow-derived macrophages, and these effects were reversed by a TGFBR2 inhibitor. In addition, as a carrier, LDH loaded with NT3 exhibited better recovery effects with regard to the basso mouse scale score, motor evoked potential performance, and regenerated neural cell numbers than LDH itself. Thus, we have developed Mg/Al-LDH that can be used to construct a suitable immune microenvironment for SCI recovery and have revealed the targeted receptor.

Injectable hydrogels of newly designed brush biopolymers as sustained drug-delivery vehicle for melanoma treatment

Novel biocompatible and brush copolymers have been developed for cancer treatment using its controlled drug-release potential. Polyurethane graft on linear dextrin has been synthesized to control the hydrophilic-hydrophobic balance for regulated drug delivery. The properties of the graft copolymers have been tuned through graft density. The prepared grafts are thermally stable and mechanically strong. An injectable hydrogel has been developed by embedding the drug-loaded brush copolymers in methyl cellulose to better control the release for a prolonged period, importantly by keeping the drug release at a constant rate. Cellular studies indicate the biocompatible nature of the brush copolymers whose controlled and slow release of drug exhibit significant cytotoxic effects on cancer cells. Endocytosis of drug tagged contrast agent indicates greater transport of biologically active material inside cell as observed through cellular uptake studies. In vivo studies on melanoma mice exhibit the real efficacy of the controlled drug release from the injectable hydrogel with significant melanoma suppression without any side effects as opposed to severe toxic effects observed in conventional chemotherapy. Special application method of drug-loaded hydrogel just beneath the tumor makes this system incredibly effective through confinement. Thus, brush copolymer injectable hydrogel is a promising vehicle for control release of drug for cancer treatment in future.

Evolution of drug-eluting biomedical implants for sustained drug delivery

In the field of drug delivery, the most commonly used treatments have traditionally been systemically delivered using oral or intravenous administration. The problems associated with this type of delivery is that the drug concentration is controlled by first pass metabolism, and therefore may not always remain within the therapeutic window. Implantable drug delivery systems (IDDSs) are an excellent alternative to traditional delivery because they offer the ability to precisely control the drug release, deliver drugs locally to the target tissue, and avoid the toxic side effects often experienced with systemic administration. Since the creation of the first FDA-approved IDDS in 1990, there has been a surge in research devoted to fabricating and testing novel IDDS formulations. The versatility of these systems is evident when looking at the various biomedical applications that utilize IDDSs. This review provides an overview of the history of IDDSs, with examples of the different types of IDDS formulations, as well as looking at current and future biomedical applications for such systems. Though there are still obstacles that need to be overcome, ever-emerging new technologies are making the manufacturing of IDDSs a rewarding therapeutic endeavor with potential for further improvements.

Hybrid Acrylated Chitosan and Thiolated Pectin Cross-Linked Hydrogels with Tunable Properties

We developed and characterized a new hydrogel system based on the physical and chemical interactions of pectin partially modified with thiol groups and chitosan modified with acrylate end groups. Gelation occurred at high pectin thiol ratios, indicating that a low acrylated chitosan concentration in the hydrogel had a profound effect on the cross-linking. Turbidity, Fourier transform infrared spectroscopy, and free thiol determination analyses were performed to determine the relationships of the different bonds inside the gel. At low pH values below the pKa of chitosan, more electrostatic interactions were formed between opposite charges, but at high pH values, the Michael-type addition reaction between acrylate and thiol took place, creating harder hydrogels. Swelling experiments and Young’s modulus measurements were performed to study the structure and properties of the resultant hydrogels. The nanostructure was examined using small-angle X-ray scattering. The texture profile analysis showed a unique property of hydrogel adhesiveness. By implementing changes in the preparation procedure, we controlled the hydrogel properties. This hybrid hydrogel system can be a good candidate for a wide range of biomedical applications, such as a mucosal biomimetic surface for mucoadhesive testing.

From waste of marine culture to natural patch in cardiac tissue engineering

Sea squirt, as a highly invasive species and main biofouling source in marine aquaculture, has seriously threatened the biodiversity and aquaculture economy. On the other hand, a conductive biomaterial with excellent biocompatibility, and appropriate mechanical property from renewable resources is urgently required for tissue engineering patches. To meet these targets, we presented a novel and robust strategy for sustainable development aiming at the marine pollution via recycling and upgrading the waste biomass-sea squirts and serving as a renewable resource for functional bio-scaffold patch in tissue engineering. We firstly demonstrated that the tunic cellulose derived natural self-conductive scaffolds successfully served as functional cardiac patches, which significantly promote the maturation and spontaneous contraction of cardiomyocytes both in vitro and enhance cardiac function of MI rats in vivo. We believe this novel, feasible and “Trash to Treasure” strategy to gain cardiac patches via recycling the waste biomass must be promising and beneficial for marine environmental bio-pollution issue and sustainable development considering the large-scale consumption potential for tissue engineering and other applications.

•

Fouling sea squirts used as scaffold materials can effectively solve the pollution problem of marine aquaculture.

•

The natural electrical conductivity of the sea squirts derived scaffold is similar to that of natural myocardial tissue.

•

Cellulose scaffold from sea squirts has a good orientation, and its structure is similar to natural myocardial tissue.

•

Sea squirts cellulose derived natural self-conductive scaffolds were successfully served as the functional cardiac patches.

Stimuli-Responsive Biomolecule-Based Hydrogels and Their Applications

This Review presents polysaccharides, oligosaccharides, nucleic acids, peptides, and proteins as functional stimuli-responsive polymer scaffolds that yield hydrogels with controlled stiffness. Different physical or chemical triggers can be used to structurally reconfigure the crosslinking units and control the stiffness of the hydrogels. The integration of stimuli-responsive supramolecular complexes and stimuli-responsive biomolecular units as crosslinkers leads to hybrid hydrogels undergoing reversible triggered transitions across different stiffness states. Different applications of stimuli-responsive biomolecule-based hydrogels are discussed. The assembly of stimuli-responsive biomolecule-based hydrogel films on surfaces and their applications are discussed. The coating of drug-loaded nanoparticles with stimuli-responsive hydrogels for controlled drug release is also presented.

Evaluation of the subtle trade-off between physical stability and thermo-responsiveness in crosslinked methylcellulose hydrogels

Methylcellulose (MC) hydrogels, undergoing sol-gel reversible transition upon temperature changes, lend themselves to smart system applications. However, their reduced stability in aqueous environment and unsatisfactory mechanical properties limit the breadth of their possible applications. Here, a crosslinking strategy based on citric acid (CA) was developed: exploiting three crosslinking parameters (CA concentration, crosslinking time, and crosslinking temperature) by a design of experiment approach, optimized crosslinked MC hydrogels (MC-L, MC-M, MC-H) were obtained and characterized. Swelling tests in water revealed the effectiveness of CA crosslinking in modulating the water uptake of MC hydrogels. Both theoretical and experimental analyses showed an increase in the crosslinking density by the rationale selection of process parameters. The extent of sol-gel transition was assessed by swelling tests, Raman spectroscopy and rheological analyses. MC-M samples demonstrated to preserve their thermo-responsive behavior around their lower critical solution temperature (LCST), while showing increased stability and enhanced mechanical properties when compared to pristine MC hydrogels.

Composite Microgels Created by Complexation between Polyvinyl Alcohol and Graphene Oxide in Compressed Double-Emulsion Drops

Microgels, microparticles made of hydrogels, show fast diffusion kinetics and high reconfigurability while maintaining the advantages of hydrogels, being useful for various applications. Here, presented is a new microfluidic strategy for producing polymer-graphene oxide (GO) composite microgels without chemical cues or a temperature swing for gelation. As a main component of microgels, polymers that are able to form hydrogen bonds, such as polyvinyl alcohol (PVA), are used. In the mixture of PVA and GO, GO is tethered by PVA through hydrogen bonding. When the mixture is rapidly concentrated in the core of double-emulsion drops by osmotic-pressure-driven water pumping, PVA-tethered GO sheets form a nematic phase with a planar alignment. In addition, the GO sheets are linked by additional hydrogen bonds, leading to a sol-gel transition. Therefore, the PVA-GO composite remains undissolved when it is directly exposed to water by oil-shell rupture. These composite microgels can be also produced using poly(ethylene oxide) or poly(acrylic acid), instead of PVA. In addition, the microgels can be functionalized by incorporating other polymers in the presence of the hydrogel-forming polymers. It is shown that the multicomponent microgels made from a mixture of polyacrylamide, PVA, and GO show an excellent adsorption capacity for impurities.

Aggregation behaviors of thermo-responsive methylcellulose in water: A molecular dynamics simulation study

The aggregation behaviors of methylcellulose (MC) in aqueous solution were investigated using all-atom molecular dynamic simulations (MD). The interactions between MC chains and water molecules at different temperatures were investigated by a series of MD analyses, such as the solvent accessible surface area, number of hydrogen bonds, radial distribution functions and the interaction energies. Constant temperature simulations and heating simulations of MC aqueous solution were carried out in this work. In the simulations at three constant temperatures (25 °C, 50 °C and 75 °C), the aggregation behaviors of MC chains were affected by the temperature. In the heating simulation (25 °C ∼ 75 °C), temperature increases were accompanied by decreases in interactions between MC and water molecules, and by increases in interactions between MC chains, which led to the aggregation of MC chains. The degree of aggregation of MC chains increased with the rise of temperature.