Multi-functional chitosan-based smart hydrogels mediated biomedical application

Multifunctional sorafenib-loaded MXene for enhanced cancer therapy: In vitro and in vivo study based on chemotherapy/photothermal therapy approach

Cancer, characterized by uncontrolled cell proliferation, remains one of the deadliest diseases. Multifunctional hybrid nanosystems that combine drugs with photothermal therapy (PTT) offer enhanced tumor treatment options through localized thermal increase and smart drug delivery (SDD). MXene, a 2D inorganic nanomaterial consisting of titanium carbide (Ti3C2), has garnered significant interest for cancer applications. MXene was combined with the metal-organic framework MOF-UiO-67 to create MX-Uio-67. The anticancer drug sorafenib (SN) was then load onto MX-UiO-67 and coated with chitosan (CS) to form SN-MX-UiO-67@CS aiming to improve chemo-PTT mediated by near-infrared (NIR) laser irradiation. The release of SN from SN-MX-UiO-67@CS was studied at pH 4.6 and pH 7.4 conditions, both with and without NIR, over a period of 96 h. The cumulative release of SN from MX-UiO-67@CS reached 80.16 % at pH 7.4 and 93.77 % at pH 4.6 under NIR irradiation. MTT assay results demonstrated significant cytotoxicity against HepG2 cells, with SN-MX-UiO-67@CS (chemo-PTT) displaying an IC50 value of 22.4 µg/mL and achieving a necrosis was 36.1 % and apoptosis rate of 50.94 %, highlighting its potential as an effective anticancer agent. Furthermore, in vivo PTT via xenograft model and biodistribution studies were performed in healthy BALB/c mice under NIR. A bio-analytical technique was established utilizing HepG2 cells for the quantitative examination of SN in mice plasma, spleen, liver, heart, kidneys, tumor and lungs. A highly significant difference was observed in the plasma concentration-time curves and pharmacokinetic parameters of SN, SN-MX, and SN-MX-UiO-67following the intravenous administration of SN-MX-UiO-67@CS. Notably, the formulation exhibited higher key pharmacokinetic parameters, involving Cmax and AUC(0-72).

Multifunctional phenylboric acid modified carboxymethyl chitosan based hydrogel crosslinked by tannic acid

Hydrogels prepared from natural polysaccharide, such as chitosan, have attracted much attention owing to their advantageous physicochemical properties and functions. Therefore, it is of great significance to develop novel crosslinking and preparation methods for hydrogels. Here, a class of multifunctional chitosan-based (CBT) hydrogels were prepared from 3-carboxy-5-nitrophenylboronic acid (PBA) modified carboxymethyl chitosan (CMCS) and tannic acid (TA) by double crosslinking of borate ester and hydrogen bonds. They could rapidly gel within 1 min through physical blending under physiological conditions. They had good physicochemical properties such as injectability, plasticity, self-healing, swelling and biodegradability. They also exhibited the inherent viscoelastic behavior of hydrogels and had a maximum compressive strength of up to 0.31 Mpa. Moreover, they had excellent biocompatibility, hemostatic ability and antioxidant ability. Their maximum antibacterial rate against S. aureus and E.coli were up to 85.22 ± 2.73 % and 48.50 ± 1.04 %, respectively. They could be loaded with the model drug curcumin through borate ester bond and achieve glucose-sensitive controlled release. Preliminary in vivo experiments also showed good biosafety and degradability. Therefore, the multifunctional hydrogels provided a new approach for the design of polysaccharide-based hydrogels, and could potentially be applied in wound repair, drug delivery and other biomedical fields.

Molecular insights into the antineoplastic potential of apigenin and its derivatives: paving the way for nanotherapeutic innovations

INTRODUCTION

Apigenin, a widely distributed bioactive flavonoid, has recently gained excellent attention among researchers as an effective anticancer drug that can alternate cancer-signaling pathways, induce programmed cell death, and reduce tumor growth in various cancer types. Despite its impressive anti-neoplastic activity, high hydrophobicity, and nonspecific biodistribution make apigenin difficult for pharmaceutical applications.

AREAS COVERED

We highlighted the therapeutic potential of apigenin and its derivatives in different cancer types, along with their mechanism of action. Nanoengineered drug delivery systems have remarkable applications in minimizing drug degradation and enhancing the therapeutic efficacy of drugs with sustained release, prolonged blood retention time, and reduced off-target toxicities. This review has evaluated and explored the molecular interactions of this novel flavonoid in various cancer signaling pathways to selectively inhibit neoplastic development in multiple cancer types. To ensure the complete coverage of the explored research area, Google Scholar, PubMed, and Web of Science were used to find not only the most relevant but also connected and similar articles.

EXPERT OPINION

A comprehensive overview of apigenin nanotherapy in cancer treatment can establish a platform to overcome its difficulties for pharmaceutical applications and efficient clinical translation from bench to bedside.

Polydopamine Nanocomposite Hydrogel for Drug Slow-Release in Bone Defect Repair: A Review of Research Advances

In recent years, hydrogels have emerged as promising candidates for bone defect repair due to their excellent biocompatibility, high porosity, and water-retentive properties. However, conventional hydrogels face significant challenges in clinical translation, including brittleness, low mechanical strength, and poorly controlled drug degradation rates. To address these limitations, as a multifunctional polymer, polydopamine (PDA) has shown great potential in both bone regeneration and drug delivery systems. Its robust adhesive properties, biocompatibility, and responsiveness to photothermal stimulation make it an ideal candidate for enhancing hydrogel performance. Integrating PDA into conventional hydrogels not only improves their mechanical properties but also creates an environment conducive to cell adhesion, proliferation, and differentiation, thereby promoting bone defect repair. Moreover, PDA facilitates controlled drug release, offering a promising approach to optimizing treatment outcomes. This paper first explores the mechanisms through which PDA promotes bone regeneration, laying the foundation for its clinical translation. Additionally, it discusses the application of PDA-based nanocomposite hydrogels as advanced drug delivery systems for bone defect repair, providing valuable insights for both research and clinical translation.

Morin-Loaded Chitosan-Poloxamer Hydrogel as an Osteoinductive Delivery System for Endodontic Applications

Considering the search for new biocompatible intracanal medicaments that can preserve remaining cells and stimulate bone tissue repair in the periapical region, this study aimed to synthesize and characterize the physicochemical properties of morin-loaded chitosan-poloxamer hydrogel (MCP) as well as to evaluate its osteogenic potential. Morin hydrate (M) was loaded into chitosan-poloxamer (CP) hydrogel and the resulting particles were characterized by infrared spectroscopy (FTIR), UV-vis spectrophotometer and scanning electron microscopy. Biological assays evaluated the metabolic activity, cell morphology and alkaline phosphatase (ALP) activity of human bone marrow stem cells (HBMSC) in three different settings, such as the exposure to dissolved morin, hydrogel's leachates and assembled particles by indirect contact. Cells cultured in standard culture conditions were used as control. The effect of CP and MCP particles on the formation of collagenous and mineralized tissues was also assessed within the organotypic model of segmented embryonic chick femora. Datasets were assessed for one-way analysis of variance (ANOVA), followed by Tukey's post hoc test (p < 0.05). Morin at 50 μg/mL was cytocompatible and increased ALP activity. CP and MCP particles showed stability, and morin was entrapped in the hydrogel matrix without changing its chemical structure. Cultures treated with 30-min CP and MCP hydrogel leachates presented significantly higher metabolic activity compared to control. By indirect contact, CP particles increased metabolic activity, but only MCP particles induced an upregulation of ALP activity in comparison to control. The amount of collagenous tissue and mineralized area on the fractured embryonic chick femora was greater in MCP particles compared to CP counterparts. Chitosan-poloxamer platforms are suitable systems to delivery morin, enhancing cell proliferation and bone mineralization, which upholds its application as intracanal medication for endodontic purposes.

Synergistic effects of doxorubicin loaded silk fibroin nanoparticles and Cu-TiO2 nanoparticles for local chemo-sonodynamic therapy against breast cancer

A promising new approach to mitigate the adverse effects of chemotherapeutic drugs on healthy tissues involves combining sonodynamic therapy with topical chemotherapy to enhance the therapeutic efficacy of anticancer drugs. In this study, we introduce a multi-functional in situ chitosan hydrogel (CS) containing silk fibroin nanoparticles (SFNPs) loaded with doxorubicin (DOXSFNPs) and CuO/TiO2 nanoparticles (CTNPs) for combination therapy. The developed DOXSFNPs exhibited a size of 257 ± 6 nm, a zeta potential of -14.3 ± 1.8 mV, and a high loading capacity of 12.38 ± 1.73 %. The pH-dependent controlled release of DOX from DOXSF2/CS2 was observed to be more pronounced than that from DOX/CS2. MTT results indicated dose-dependent toxicity of CT/CS2 in response to ultrasaound radiation (US). Our findings revealed a 1.83-fold increase in reactive oxygen species (ROS) production with therapy, with the IC50 of CT3-DOXSF2/CS2-US showing a 58 % reduction compared to CT3/DOXSF2/CS2. In vivo outcomes and histopathological staining demonstrated that the CT3/DOXSF2/CS2-US treatment group exhibited the highest tumor growth inhibition rate, reaching approximately 83.65 %. These findings underscore the potential of this approach in minimizing the adverse effects of chemotherapy while maximizing therapeutic outcomes, offering a valuable contribution to the field of cancer therapy.

Supramolecular Conductive Hydrogels for Tissue Engineering Applications

Owing to their unique attributes, including reversibility, specificity, directionality, and tunability, supramolecular biomaterials have evolved as an excellent alternative to conventional biomaterials like polymers, ceramics, and metals. Supramolecular hydrogels, in particular, have garnered significant interest because their fibrous architecture, high water content, and interconnected 3D network resemble the extracellular matrix to some extent. Consequently, supramolecular hydrogels have been used to develop biomaterials for tissue engineering. Supramolecular conductive hydrogels combine the advantages of supramolecular soft materials with the electrical properties of metals, making them highly relevant for electrogenic tissue engineering. Given the versatile applications of these hydrogels, it is essential to periodically review high-quality research in this area. In this review, we focus on recent advances in supramolecular conductive hydrogels, particularly their applications in tissue engineering. We discuss the conductive components of these hydrogels and highlight notable reports on their use in cardiac, skin, and neural tissue engineering. Additionally, we outline potential future developments in this field.

Alginate-based hydrogels mediated biomedical applications: A review

With the development in the field of biomaterials, research on alternative biocompatible materials has been initiated, and alginate in polysaccharides has become one of the research hotspots due to its advantages of biocompatibility, biodegradability and low cost. In recent years, with the further understanding of microscopic molecular structure and properties of alginate, various physicochemical methods of cross-linking strategies, as well as organic and inorganic materials, have led to the development of different properties of alginate hydrogels for greatly expanded applications. In view of the potential application prospects of alginate-based hydrogels, this paper reviews the properties and preparation of alginate-based hydrogels and their major achievements in delivery carrier, dressings, tissue engineering and other applications are also summarized. In addition, the combination of alginate-based hydrogel and new technology such as 3D printing are also involved, which will contribute to further research and exploration.

Rhein-chitosan in situ hydrogel promotes wound healing in diabetic mice

Chronic inflammation and infection often lead to delayed healing in skin wounds of patients with diabetes, presenting a significant challenge in clinical wound repair. In an effort to tackle this issue, we explored the utilization of the natural compounds Rhein and chitosan in the creation of a crosslinked in situ gel. Developed as Rhein-chitosan in situ hydrogel (CS-Rh gel), this formulation has the ability to gel at body temperature, making it suitable for irregular wounds of varying shapes. Our experimental investigations have demonstrated its excellent biocompatibility, controlled release of Rhein, biodegradability, anti-inflammatory properties, antibacterial effect, as well as its ability to enhance keratinocyte proliferation and migration. Furthermore, in vivo studies have confirmed that CS-Rh gel can effectively mitigate tissue inflammation, promote collagen deposition, and significantly accelerate wound healing in diabetic mice within a short timeframe of two weeks. Consequently, this innovative approach holds promise as a viable therapeutic strategy for supporting the healing of diabetic wounds in a clinical setting.

Hydrogel-Based Treatment of House Dust Mite-Induced Atopic Dermatitis through Triple Cleaning of Mites, Bacteria, and ROS-Related Inflammation

Atopic dermatitis (AD) is a chronic and recurrent inflammatory disease caused by abnormalities in skin immunoregulation. House dust mite can directly damage the skin barrier and thus sensitize the skin, which is one of the main allergens inducing AD in humans and widely exists in daily life. Meanwhile, the accompanying bacterial infections and exposure to additional allergens exacerbate the condition by generating excessive reactive oxygen species (ROS). Herein, we have developed the CPDP hydrogel with injectable and self-healing ability to combat pathogenic microorganisms and inflammatory environments for AD therapy. In vitro experiments have affirmed the efficacy of the CPDP hydrogel in combating mites, killing bacteria, and scavenging ROS. In a mouse model closely mimicking HDM-induced AD, the CPDP hydrogel has shown superior therapeutic effects, including reducing epidermal thickness and mast cell count, increasing collagen deposition, as well as down-regulating pro-inflammatory factors.

Design and Characterization of Chitosan-Based Smart Injectable Hydrogel for Improved Sustained Release of Antinarcotics

The treatment adherence of narcotics-addicted individuals with reduced incidences of relapse can be enhanced by a sustained drug release formulation of antinarcotics. So far, different drug formulations have been reported with sustained drug release periods of 28 and 35 days. To further enhance this duration, different formulations of injectable hydrogels (IHs) have been developed by combining low molecular weight (LMW) and high molecular weight (HMW) chitosan (CS) with guar gum (GG) and crosslinking them by sodium bi phosphate dibasic. The structural, morphological, and physicochemical properties of LMW-CS IH, and HMW-CS IH were evaluated using Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), and rheological, swelling, and biodegradation analysis. The HMW-CS IH showed high crosslinking, increased thermal stability, high mechanical strength, elevated swelling, and low biodegradation. The antinarcotic drugs naltrexone (NTX) and disulfiram (DSF) were loaded separately into the HMW-CS IH and LMW-CS IH. The release of NTX and DSF was investigated in phosphate buffer saline (PBS) and ethanol (0.3%, 0.4%, and 0.5%) over a 56-day period using an UV spectrophotometer. The drug release data were tested in zero-order, first-order, and Korsemeyer-Peppas mathematical models. In PBS, all prepared formulations followed non-Fickian drug release, while in ethanol, only NTX HMW-CS IH followed non-Fickian release in all three different concentrations of ethanol.

Multifunctional antibacterial hydrogels for chronic wound management

Chronic wounds have gradually evolved into a global health challenge, comprising long-term non-healing wounds, local tissue necrosis, and even amputation in severe cases. Accordingly, chronic wounds place a considerable psychological and economic burden on patients and society. Chronic wounds have multifaceted pathogenesis involving excessive inflammation, insufficient angiogenesis, and elevated reactive oxygen species levels, with bacterial infection playing a crucial role. Hydrogels, renowned for their excellent biocompatibility, moisture retention, swelling properties, and oxygen permeability, have emerged as promising wound repair dressings. However, hydrogels with singular functions fall short of addressing the complex requirements associated with chronic wound healing. Hence, current research emphasises the development of multifunctional antibacterial hydrogels. This article reviews chronic wound characteristics and the properties and classification of antibacterial hydrogels, as well as their potential application in chronic wound management.

Biomedical Trends in Stimuli-Responsive Hydrogels with Emphasis on Chitosan-Based Formulations

Biomedicine is constantly evolving to ensure a significant and positive impact on healthcare, which has resulted in innovative and distinct requisites such as hydrogels. Chitosan-based formulations stand out for their versatile utilization in drug encapsulation, transport, and controlled release, which is complemented by their biocompatibility, biodegradability, and non-immunogenic nature. Stimuli-responsive hydrogels, also known as smart hydrogels, have strictly regulated release patterns since they respond and adapt based on various external stimuli. Moreover, they can imitate the intrinsic tissues' mechanical, biological, and physicochemical properties. These characteristics allow stimuli-responsive hydrogels to provide cutting-edge, effective, and safe treatment. Constant progress in the field necessitates an up-to-date summary of current trends and breakthroughs in the biomedical application of stimuli-responsive chitosan-based hydrogels, which was the aim of this review. General data about hydrogels sensitive to ions, pH, redox potential, light, electric field, temperature, and magnetic field are recapitulated. Additionally, formulations responsive to multiple stimuli are mentioned. Focusing on chitosan-based smart hydrogels, their multifaceted utilization was thoroughly described. The vast application spectrum encompasses neurological disorders, tumors, wound healing, and dermal infections. Available data on smart chitosan hydrogels strongly support the idea that current approaches and developing novel solutions are worth improving. The present paper constitutes a valuable resource for researchers and practitioners in the currently evolving field.

Application of Chitosan-Based Hydrogel in Promoting Wound Healing: A Review

Chitosan is a linear polyelectrolyte with active hydroxyl and amino groups that can be made into chitosan-based hydrogels by different cross-linking methods. Chitosan-based hydrogels also have a three-dimensional network of hydrogels, which can accommodate a large number of aqueous solvents and biofluids. CS, as an ideal drug-carrying material, can effectively encapsulate and protect drugs and has the advantages of being nontoxic, biocompatible, and biodegradable. These advantages make it an ideal material for the preparation of functional hydrogels that can act as wound dressings for skin injuries. This review reports the role of chitosan-based hydrogels in promoting skin repair in the context of the mechanisms involved in skin injury repair. Chitosan-based hydrogels were found to promote skin repair at different process stages. Various functional chitosan-based hydrogels are also discussed.

Architecturally designed sequential-release hydrogels

Drug synergy has made significant strides in clinical applications in recent decades. However, achieving a platform that enables "single administration, multi-stage release" by emulating the natural physiological processes of the human body poses a formidable challenge in the field of molecular pharmaceutics. Hydrogels, as the novel generation of drug delivery systems, have gained widespread utilization in drug platforms owing to their exceptional biocompatibility and modifiability. Sequential drug delivery hydrogels (SDDHs), which amalgamate the advantages of hydrogel and sequential release platforms, offer a promising solution for effectively navigating the intricate human environment and accomplishing drug sequential release. Inspired by architectural design, this review establishes connections between three pivotal factors in SDDHs construction, namely mechanisms, carrier spatial structure, and stimuli-responsiveness, and three aspects of architectural design, specifically building materials, house structures, and intelligent interactive furniture, aiming at providing insights into recent developments in SDDHs. Furthermore, the dual-drug collocation and cutting-edge hydrogel preparation technologies as well as the prevailing challenges in the field were elucidated.

Recent advances in chitosan-based materials; The synthesis, modifications and biomedical applications

The attention to polymer-based biomaterials, for instance, chitosan and its derivatives, as well as the techniques for using them in numerous scientific domains, is continuously rising. Chitosan is a decomposable naturally occurring polymeric material that is mostly obtained from seafood waste. Because of its special ecofriendly, biocompatible, non- toxic nature as well as antimicrobial properties, chitosan-based materials have received a lot of interest in the field of biomedical applications. The reactivity of chitosan is mainly because of the amino and hydroxyl groups in its composition, which makes it further fascinating for various uses, including biosensing, textile finishing, antimicrobial wound dressing, tissue engineering, bioimaging, gene, DNA and drug delivery and as a coating material for medical implants. This study is an overview of the different types of chitosan-based materials which now a days have been fabricated by applying different techniques and modifications that include etherification, esterification, crosslinking, graft copolymerization and o-acetylation etc. for hydroxyl groups' processes and acetylation, quaternization, Schiff's base reaction, and grafting for amino groups' reactions. Furthermore, this overview summarizes the literature from recent years related to the important applications of chitosan-based materials (i.e., thin films, nanocomposites or nanoparticles, sponges and hydrogels) in different biomedical applications.

Chitosan and its derivatives in 3D/4D (bio) printing for tissue engineering and drug delivery applications

Tissue engineering research has undergone to a revolutionary improvement, thanks to technological advancements, such as the introduction of bioprinting technologies. The ability to develop suitable customized biomaterial inks/bioinks, with excellent printability and ability to promote cell proliferation and function, has a deep impact on such improvements. In this context, printing inks based on chitosan and its derivatives have been instrumental. Thus, the current review aims at providing a comprehensive overview on chitosan-based materials as suitable inks for 3D/4D (bio)printing and their applicability in creating advanced drug delivery platforms and tissue engineered constructs. Furthermore, relevant strategies to improve the mechanical and biological performances of this biomaterial are also highlighted.

UV cross-linked injectable non-swelling dihydrocaffeic acid grafted chitosan hydrogel for promoting wound healing

Hydrogels are widely used as wound dressings for wound healing, but when hydrogels absorb wound exudate, swelling occurs and compresses the surrounding tissue, affecting healing. A chitosan injectable (CS/4-PA/CAT) hydrogel based on catechol and 4-glutenoic acid was prepared to avoid swelling and promote wound healing. After cross-linking by UV light, pentenyl groups formed hydrophobic alkyl chains which give the hydrogel a hydrophobic network and thus control its swelling. CS/4-PA/CAT hydrogels retained their non-swelling for a long time in PBS solution at 37 °C. CS/4-PA/CAT hydrogels had good injectable and adhesive properties, and had a good killing effect on E. coli and S. aureus and could remove the bacterial biofilms of E. coli and S. aureus. CS/4-PA/CAT hydrogels had good in vitro coagulation function by absorbing red blood cells and platelets. When used in a whole skin injury model, CS/4-PA/CAT-1 hydrogel stimulated fibroblast migration, promoted epithelialization and accelerated collagen deposition to promote defect healing, and showed good hemostatic effects in liver and femoral artery defects in mice. In summary, the non-swelling injectable hydrogel with free radical scavenging, rapid hemostasis, and antibacterial effects would be a promising treatment for defect repair.

Chitosan-based hydrogel wound dressing: From mechanism to applications, a review

As promising biomaterials, hydrogels are widely used in the medical engineering field, especially in wound repairing. Compared with traditional wound dressings, such as gauze and bandage, hydrogel could absorb and retain more water without dissolving or losing its three-dimensional structure, thus avoiding secondary injury and promoting wound healing. Chitosan and its derivatives have become hot research topics for hydrogel wound dressing production due to their unique molecular structure and diverse biological activities. In this review, the mechanism of wound healing was introduced systematically. The mechanism of action of chitosan in the first three stages of wound repair (hemostasis, antimicrobial properties and progranulation), the effect of chitosan deacetylation and the molecular weight on its performance are analyzed. Additionally, the recent progress in intelligent and drug-loaded chitosan-based hydrogels and the features and advantages of chitosan were discussed. Finally, the challenges and prospects for the future development of chitosan-based hydrogels were discussed.

The evaluation of chitosan hydrogel based curcumin effect on DNMT1, DNMT3A, DNMT3B, MEG3, HOTAIR gene expression in glioblastoma cell line

BACKGROUND

Cancer is one of the most important causes of death worldwide. Some types of cancer, including glioblastoma, with a high potential for growth, invasion, and resistance to general treatments, chemotherapy, and radiotherapy, have a high potential for recurrence. Many chemical drugs have been used to treat it, but herbal drugs are more effective with fewer side effects; Therefore, this research aims to investigate the effect of curcumin-chitosan nano-complex on the expression of MEG3, HOTAIR, DNMT1, DNMT3A, DNMT3B genes in the glioblastoma cell line.

METHODS

In this research, glioblastoma cell line, PCR and spectrophotometry techniques, MTT test and transmission, field emission transmission, and fluorescent electron microscopes were used.

RESULTS

The morphological examination of the curcumin-chitosan nano-complex was without clumping, and the fluorescent microscope examination showed the nano-complex enters the cell and affects the genes expression. In its bioavailability studies, it was found that it significantly increases the death of cancer cells in a dose- and time-dependent manner. Gene expression tests showed that this nano-complex increased MEG3 gene expression compared to the control group, which is statistically significant (p < 0.05). It also decreased HOTAIR gene expression compared to the control group, which was not statistically significant (p > 0.05). It decreased the expression of DNMT1, DNMT3A, and DNMT3B genes compared to the control group, which is statistically significant (p < 0.05).

CONCLUSION

By using active plant substances such as curcumin, the active demethylation of brain cells can be directed to the path of inhibiting the growth of brain cancer cells and eliminating them.

Synthesis, Characterization, Properties, and Biomedical Application of Chitosan-Based Hydrogels

The prospective applications of chitosan-based hydrogels (CBHs), a category of biocompatible and biodegradable materials, in biomedical disciplines such as tissue engineering, wound healing, drug delivery, and biosensing have garnered great interest. The synthesis and characterization processes used to create CBHs play a significant role in determining their characteristics and effectiveness. The qualities of CBHs might be greatly influenced by tailoring the manufacturing method to get certain traits, including porosity, swelling, mechanical strength, and bioactivity. Additionally, characterization methods aid in gaining access to the microstructures and properties of CBHs. Herein, this review provides a comprehensive assessment of the state-of-the-art with a focus on the affiliation between particular properties and domains in biomedicine. Moreover, this review highlights the beneficial properties and wide application of stimuli-responsive CBHs. The main obstacles and prospects for the future of CBH development for biomedical applications are also covered in this review.

Applications of Stimuli-Responsive Hydrogels in Bone and Cartilage Regeneration

Bone and cartilage regeneration is an area of tremendous interest and need in health care. Tissue engineering is a potential strategy for repairing and regenerating bone and cartilage defects. Hydrogels are among the most attractive biomaterials in bone and cartilage tissue engineering, mainly due to their moderate biocompatibility, hydrophilicity, and 3D network structure. Stimuli-responsive hydrogels have been a hot topic in recent decades. They can respond to external or internal stimulation and are used in the controlled delivery of drugs and tissue engineering. This review summarizes current progress in the use of stimuli-responsive hydrogels in bone and cartilage regeneration. The challenges, disadvantages, and future applications of stimuli-responsive hydrogels are briefly described.

Chitosan/glycyrrhizic acid hydrogel: Preparation, characterization, and its potential for controlled release of gallic acid

In the present work, chitosan (CHT) as a biodegradable polymer was crosslinked using various amounts of glycyrrhizic acid (GLA) as a novel crosslinking agent to prepare biocompatible hydrogels. The prepared hydrogels were used for the controlled release of gallic acid (GA) in transdermal therapy application. FTIR, XRD, and SEM were used to characterize the prepared gels. The results indicated that the carboxylic acid groups of GLA react with the amine groups of the CHT in the presence of activating coupling reagents to form covalent amide linkage between the polymer chains of CHT and construct CHT cross-linked hydrogel (CCH) network structure. The prepared CCH samples were characterized and used for the controlled release of a drug, i.e. (GA). For this purpose, the swelling kinetic, loading and encapsulation efficiency, in vitro drug release, drug release kinetics, cell viability assay, and anti-bacterial activity of the samples were evaluated. The swelling ratio of CCH samples were in the range of 455-37 % depending on the pH of environment. Swelling kinetic results showed an aggregate to the non-linear second-order kinetic model. Drug release results were fitted by kinetic models while the Korsmeyer-Peppas model was fitted better. The CCH samples exhibited high biocompatibility for 5 mg/ml hydrogel concentration. In addition, the CHT and CCH sample without the GA did not show anti-bacterial properties for 1200 and 150 μg/ml concentrations, respectively. The CCH sample containing the GA exhibited enough anti-bacterial activity on the S. aureus bacteria strain at 150 μg/ml concentration. In contrast, the CCH sample containing the GA has a light anti-bacterial effect on the E. coli bacteria strain. The calculated mesh size of hydrogel networks, drug size, and kinetics models revealed that the CCH samples could release GA based on a diffusion mechanism. In conclusion, the designed CCH samples have enough ability for controlled drug release in transdermal applications.

Research progress in decellularized extracellular matrix hydrogels for intervertebral disc degeneration

As one of the most common clinical disorders, low back pain (LBP) influences patient quality of life and causes substantial social and economic burdens. Many factors can result in LBP, the most common of which is intervertebral disc degeneration (IDD). The progression of IDD cannot be alleviated by conservative or surgical treatments, and gene therapy, growth factor therapy, and cell therapy have their own limitations. Recently, research on the use of hydrogel biomaterials for the treatment of IDD has garnered great interest, and satisfactory treatment results have been achieved. This article describes the classification of hydrogels, the methods of decellularized extracellular matrix (dECM) production and the various types of gel formation. The current research on dECM hydrogels for the treatment of IDD is described in detail in this article. First, an overview of the material sources, decellularization methods, and gel formation methods is given. The focus is on research performed over the last three years, which mainly consists of bovine and porcine NP tissues, while for decellularization methods, combinations of several approaches are primarily used. dECM hydrogels have significantly improved mechanical properties after the polymers are cross-linked. The main effects of these gels include induction of stem cell differentiation to intervertebral disc (IVD) cells, good mechanical properties to restore IVD height after polymer cross-linking, and slow release of exosomes. Finally, the challenges and problems still faced by dECM hydrogels for the treatment of IDD are summarised, and potential solutions are proposed. This paper is the first to summarise the research on dECM hydrogels for the treatment of IDD and aims to provide a theoretical reference for subsequent studies.

Chitosan@Puerarin hydrogel for accelerated wound healing in diabetic subjects by miR-29ab1 mediated inflammatory axis suppression

Wound healing is one of the major global health concerns in patients with diabetes. Overactivation of pro-inflammatory M1 macrophages is associated with delayed wound healing in diabetes. miR-29ab1 plays a critical role in diabetes-related macrophage inflammation. Hence, inhibition of inflammation and regulation of miR-29 expression have been implicated as new points for skin wound healing. In this study, the traditional Chinese medicine, puerarin, was introduced to construct an injectable and self-healing chitosan@puerarin (C@P) hydrogel. The C@P hydrogel promoted diabetic wound healing and accelerated angiogenesis, which were related to the inhibition of the miR-29 mediated inflammation response. Compared to healthy subjects, miR-29a and miR-29b1 were ectopically increased in the skin wound of the diabetic model, accompanied by upregulated M1-polarization, and elevated levels of IL-1β and TNF-α. Further evaluations by miR-29ab1 knockout mice exhibited superior wound healing and attenuated inflammation. The present results suggested that miR-29ab1 is essential for diabetic wound healing by regulating the inflammatory response. Suppression of miR-29ab1 by the C@P hydrogel has the potential for improving medical approaches for wound repair.

•

A chitosan based hydrogel containing puerarin was constructed for promoting diabetic wound healing.

•

Chitosan@Puerarin hydrogel accelerated skin repair through inhibiting M1-polarization and reducing IL-1β and TNF-α.

•

miR-29 a/b1 was found to be ectopic increased in the skin-wound of diabetic model.

•

miR-29 a/b1 was inhibited by Chitosan@Puerarin in diabetic wound healing.

Chitosan-based scaffolds as drug delivery systems in bone tissue engineering

The bone tissue engineering approach for treating large bone defects becomes necessary when the tissue damage surpasses the threshold of the inherent regenerative ability of the human body. A myriad of natural biodegradable polymers and scaffold fabrication techniques have emerged in the last decade. Chitosan (CS) is especially attractive as a bone scaffold material to support cell attachment and proliferation and mineralization of the bone matrix. The primary amino groups in CS are responsible for properties such as controlled drug release, mucoadhesion, in situ gelation, and transfection. CS-based smart drug delivery scaffolds that respond to environmental stimuli have been reported to have a localized sustained delivery of drugs in the large bone defect area. This review outlines the recent advances in the fabrication of CS-based scaffolds as a pharmaceutical carrier to deliver drugs such as antibiotics, growth factors, nucleic acids, and phenolic compounds for bone tissue regeneration.

Herb Polysaccharide-Based Drug Delivery System: Fabrication, Properties, and Applications for Immunotherapy

Herb polysaccharides (HPS) have been studied extensively for their healthcare applications. Though the toxicity was not fully clarified, HPS were widely accepted for their biodegradability and biocompatibility. In addition, as carbohydrate polymers with a unique chemical composition, molecular weight, and functional group profile, HPS can be conjugated, cross-linked, and functionally modified. Thus, they are great candidates for the fabrication of drug delivery systems (DDS). HPS-based DDS (HPS-DDS) can bypass phagocytosis by the reticuloendothelial system, prevent the degradation of biomolecules, and increase the bioavailability of small molecules, thus exerting therapeutic effects. In this review, we focus on the application of HPS as components of immunoregulatory DDS. We summarize the principles governing the fabrication of HPS-DDS, including nanoparticles, micelles, liposomes, microemulsions, hydrogels, and microneedles. In addition, we discuss the role of HPS in DDS for immunotherapy. This comprehensive review provides valuable insights that could guide the design of effective HPS-DDS.

Smart biomaterials: From 3D printing to 4D bioprinting

This century is blessed with enhanced medical facilities on the grounds of the development of smart biomaterials. The rise of the four-dimensional (4D) bioprinting technology is a shining example. Using inert biomaterials as the bioinks for the three-dimensional (3D) printing process, static objects that might not be able to mimic the dynamic nature of tissues would be fabricated; by contrast, 4D bioprinting can be used for the fabrication of stimuli-responsive cell-laden structures that can evolve with time and enable engineered tissues to undergo morphological changes in a pre-planned way. For all the aptitude of 4D bioprinting technology in tissue engineering, it is imperative to select suitable stimuli-responsive biomaterials with cell-supporting functionalities and responsiveness; as a result, in this article, recent advances and challenges in smart biomaterials for 4D bioprinting are briefly discussed. An overview perspective concerning the latest developments in 4D-bioprinting is also provided.

Stiff and Tough Hydrogels Prepared Through Integration of Ionic Cross-linking and Enzymatic Mineralization

Enzymatic mineralization has become an effective approach to enhancing the stiffness of hydrogels for bone tissue engineering, but generally with limited toughness. On the other hand, double network cross-linking provides hydrogel with enhanced toughness. In this study, we integrated double cross-linking method with enzymatic mineralization to synthesize stiff and tough hydrogels. We have synthesized three kinds of sodium alginate-polyacrylamide (SA-PAM) double-network hydrogels and systematically compared the composition and structure differences, mechanical properties, and biological properties of the different hydrogels in the absence and presence of mineralization. In particular, we examined the role of specific cross-linking ions, i.e., calcium, zinc and strontium ions, in modulating the mineralization process. Synergistic effect of ionic cross-linking and enzymatic mineralization was clearly observed with dramatic increase in compressive modulus. In particular, mineralized hydrogel cross-linked with Sr2+ showed the highest compressive Young's modulus of 17.28 ± 3.56 MPa, which was 37 times of that of the original hydrogel. In addition, it had the highest tensile Young's modulus at 2.60 ± 0.25 MPa and 84 ± 5.5% elongation at break. Such synergistic effect from Sr2+ was attributed to a more uniformed mineralization process due to the early initiation of a more homogeneous nucleation process and subsequent denser mineralized structure. Cellular study also suggested that cell proliferation, adhesion and osteogenic differentiation were improved as a result of enzymatic mineralization. Our results provided an effective way for the preparation of stiff and tough hydrogels with osteogenesis, and demonstrated potential in bone tissue engineering applications. STATEMENT OF SIGNIFICANCE: : Hydrogels with excellent stiffness, stability and biocompatibility have attracted significant attentions in the bone tissue engineering applications. Our results suggested that the synergistic effect of ionic cross-linking and enzymatic mineralization rendered more enhancement of the compressive and tensile stiffness of SA-PAM DN hydrogels, as well as the toughness, swelling stability and cellular response. In particular, mineralized hydrogel cross-linked with Sr2+ showed the highest compressive Young's modulus of 17283 ± 3556KPa, which was 37 times of that of the original hydrogel. Such synergistic effect from Sr2+ was attributed to a more uniformed mineralization process. The cell proliferation, adhesion and osteogenic differentiation were greatly improved as a result of enzymatic mineralization, where the MSCs cultured on strontium ion cross-linked mineralized hydrogel showed the best performance.

Polymer-based thermoresponsive hydrogels for controlled drug delivery

INTRODUCTION

controlled drug delivery through hydrogels is generally limited by the poor barrier that polymeric network can create to diffusion mechanism. Stimuli responsive polymers can help in this way guaranteeing that delivery can be sustained and finely controlled using an external stimulus.

AREA COVERED

this review provides an overview of recent studies about the use of temperature as an external stimulus able to work as an efficient new route of drug's administration. Thermoresponsive hydrogels are discussed and compared in terms of physical properties and mechanism of drug release considering their classification in intrinsically (formed by thermosensitive polymers) and non-intrinsically (polymers with thermosensitive moieties) hydrogels.

EXPERT OPINION

thermoresponsive hydrogels can be developed by using different polymers added or not with micro/nanoparticles of organic or inorganic origin. In both cases the final system represents an innovative way for the local and sustained drug delivery in a specific site of the body. In particular, it is possible to obtain an on-demand release of drug by applying a local increase of temperature to the system.

The synthesis of bacterial cellulose-chitosan zwitterionic hydrogels with pH responsiveness for drug release mechanism of the naproxen

The human digestive and absorption system has a specific pH environment, which makes it difficult to for accurate drug-release. Zwitterionic hydrogel, as a kind of drug carrier, is a feasible response strategy. In this work, a facile method was employed to prepare a series zwitterionic hydrogels composed of BC and chitosan. The composite gels could in-situ formed via Schiff's base reaction between partially oxidated bacterial cellulose and chitosan which exhibited relatively well mechanical properties. Besides, the rich amino and carboxyl groups endowed the hydrogels with excellent pH responsive performance. The minimum swelling rate of the hydrogels appeared at pH 3.5-pH 5.0. In lower or higher pH solutions, the swelling rate was greatly increased. The drug (naproxen) loading of the hydrogels was above 110 mg/g. The release amount of naproxen in the simulated gastric juice was less than intestinal fluid with the sustained release time exceeded 24 h. Through kinetic simulation analysis, the drug release behavior is in accordance with zero-order release model. Such kind of composite hydrogel is suggested to be a potential drug carrier for clinical therapy.

Biodegradable MoO x @MB incorporated hydrogel as light-activated dressing for rapid and safe bacteria eradication and wound healing

Wounds infected with drug-resistant bacteria are hard to treat, which remains a serious problem in clinical practice. An innovative strategy for treating wound infections is thus imperative. Herein, we describe the construction of a nanocomposite from biocompatible poly(vinyl alcohol) (PVA)/polyethylene glycol (PEG) hydrogel loaded biodegradable MoO x nanoparticles (NPs) and photosensitizer methylene blue (MB), denoted as MoO x @MB-hy. By incorporating MoO x @MB NPs, the nanocomposite hydrogel can act as a photoactivated wound dressing for near-infrared-II 1064 nm and 660 nm laser synergetic photothermal-photodynamic therapy (PTT-PDT). The key to PTT-induced heat becomes the most controllable release of MB from MoO x @MB-hy to produce more 1O2 under 660 nm irradiation. Importantly, MoO x @MB-hy can consume glutathione (GSH) and trap bacteria nearer to the distance limit of ROS damage to achieve a self-migration-enhanced accumulation of reactive oxygen species (ROS), thereby conquering the intrinsic shortcomings of short diffusion distance and lifetime of ROS. Consequently, MoO x @MB-hy has high antibacterial efficiencies of 99.28% and 99.16% against Ampr E. coli and B. subtilis within 15 min. Moreover, the light-activated strategy can rapidly promote healing in wounds infected by drug-resistant bacteria. This work paves a way to design a novel nanocomposite hydrogel dressing for safe and highly-efficient antibacterial therapy.

Self-healing polysaccharide-based injectable hydrogels with antibacterial activity for wound healing

Because the wound is difficult to heal, repeated bacterial infection will lead to complex clinical problems. Therefore, it is necessary to find an effective method to strengthen the healing process and resist bacterial infection. Hydrogels have many advantages, such as injectability and self-healing under physiological conditions, so they have been widely studied in recent years. Hydrogels can keep the wound moist and promote the wound healing. In addition, the growth of bacteria can be obviously inhibited by hydrogels themself or by doping some antibacterial active substances. Based on this, herein, this review highlighted the preparation and properties of different polysaccharide-based injectable hydrogels, and discuss their biological applications in antibacterial therapy for wound healing in recent years.

Collagen-based biocomposites inspired by bone hierarchical structures for advanced bone regeneration: ongoing research and perspectives

Bone is a hard-connective tissue composed of matrix, cells and bioactive factors with a hierarchical structure, where the matrix is mainly composed of type I collagen and hydroxyapatite. Collagen fibers assembled by collagen are the template for mineralization and make an important contribution to bone formation and the bone remodeling process. Therefore, collagen has been widely clinically used for bone/cartilage defect regeneration. However, pure collagen implants, such as collagen scaffolds or sponges, have limitations in the bone/cartilage regeneration process due to their poor mechanical properties and osteoinductivity. Different forms of collagen-based composites prepared by incorporating natural/artificial polymers or bioactive inorganic substances are characterized by their interconnected porous structure and promoting cell adhesion, while they improve the mechanical strength, structural stability and osteogenic activities of the collagen matrix. In this review, various forms of collagen-based biocomposites, such as scaffolds, sponges, microspheres/nanoparticles, films and microfibers/nanofibers prepared by natural/synthetic polymers, bioactive ceramics and carbon-based materials compounded with collagen are reviewed. In addition, the application of collagen-based biocomposites as cytokine, cell or drug (genes, proteins, peptides and chemosynthetic) delivery platforms for proangiogenesis and bone/cartilage tissue regeneration is also discussed. Finally, the potential application, research and development direction of collagen-based biocomposites in future bone/cartilage tissue regeneration are discussed.

Effect of Poloxamer-Based Thermo-Sensitive Sol-Gel Agent on Upper Limb Dysfunction after Axillary Lymph Node Dissection: A Double-Blind Randomized Clinical Trial

PURPOSE

Restricted shoulder motion is a major morbidity associated with a lower quality of life and disability after axillary lymph node dissection (ALND) in patients with breast cancer. This study sought to evaluate the antiadhesive effect of a poloxamer-based thermosensitive sol-gel (PTAS) agent after ALND.

METHODS

We designed a double-blind, multicenter randomized controlled study to evaluate the clinical efficacy and safety of PTAS in reducing upper-limb dysfunction after ALND. The primary outcome was the change in the range of motion (ROM) of the shoulder before surgery and 4 weeks after ALND (early postoperative period). Secondary outcomes were shoulder ROM at six months, axillary web syndrome, and lymphedema (late postoperative period).

RESULTS

A total of 170 patients with planned ALND were randomly assigned to one of 2 groups (poloxamer and control) and 15 patients were excluded. In the poloxamer group (n = 76), PTAS was applied to the surface of the operative field after ALND. ALND was performed without the use of poloxamer in the control group (n = 79). Relative to the control group, the poloxamer group had significantly lower early postoperative restrictions in total shoulder ROM at four weeks (-30.04 ± 27.76 vs. -42.59 ± 36.79; p = 0.0236). In particular, the poloxamer group showed greater reductions in horizontal abduction at four weeks (-3.92 ± 9.80 vs. -10.25 ± 15.42; p = 0.0050). The ROM of the shoulder at 24 weeks, axillary web syndrome, and lymphedema were not significantly different between the two groups. No adverse effects were observed in either group.

CONCLUSION

We suggest that poloxamer might improve the early postoperative shoulder ROM in patients with breast cancer who have undergone ALND.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02967146.

Advances and Novel Perspectives on Colloids, Hydrogels, and Aerogels Based on Coordination Bonds with Biological Interest Ligands

This perspective article shows new advances in the synthesis of colloids, gels, and aerogels generated by combining metal ions and ligands of biological interest, such as nucleobases, nucleotides, peptides, or amino acids, among other derivatives. The characteristic dynamism of coordination bonds between metal center and biocompatible-type ligands, together with molecular recognition capability of these ligands, are crucial to form colloids and gels. These supramolecular structures are generated by forming weak van der Waals bonds such as hydrogen bonds or π–π stacking between the aromatic rings. Most gels are made up of nano-sized fibrillar networks, although their morphologies can be tuned depending on the synthetic conditions. These new materials respond to different stimuli such as pH, stirring, pressure, temperature, the presence of solvents, among others. For these reasons, they can trap and release molecules or metal ions in a controlled way allowing their application in drug delivery as antimicrobial and self-healable materials or sensors. In addition, the correct selection of the metal ion enables to build catalytic or luminescent metal–organic gels. Even recently, the use of these colloids as 3D-dimensional printable inks has been published. The elimination of the solvent trapped in the gels allows the transformation of these into metal–organic aerogels (MOAs) and metal–organic xerogels (MOXs), increasing the number of possible applications by generating new porous materials and composites useful in adsorption, conversion, and energy storage. The examples shown in this work allow us to visualize the current interest in this new type of material and their perspectives in the short-medium term. Furthermore, these investigations show that there is still a lot of work to be done, opening the door to new and interesting applications.

Degradation-Dependent Protein Release from Enzyme Sensitive Injectable Glycol Chitosan Hydrogel

Glycol chitosan (GC) is a hydrophilic chitosan derivative, known for its aqueous solubility. Previously, we have demonstrated the feasibility of preparing injectable, enzymatically crosslinked hydrogels from HPP [3-(4-Hydroxyphenyl)-propionic acid (98%)]-modified GC. However, HPP-GC gels showed very slow degradation, which presents challenges as an in vivo protein delivery vehicle. This study reports the potential of acetylated HPP-GC hydrogels as a biodegradable hydrogel platform for sustained protein delivery. Enzymatic crosslinking was used to prepare injectable, biodegradable hydrogels from HPP-GC with various degrees of acetylation (DA). The acetylated polymers were characterized using Fourier transform infrared and nuclear magnetic resonance spectroscopy. Rheological methods were used to characterize the mechanical behavior of the hydrogels. In vitro degradation and protein release were performed in the presence and absence of lysozyme. In vivo degradation was studied using a mouse subcutaneous implantation model. Finally, two hydrogel formulations with distinct in vitro/in vivo degradation and in vitro protein release were evaluated in 477-SKH1-Elite mice using live animal imaging to understand in vivo protein release profiles. The lysozyme-mediated degradation of the gels was demonstrated in vitro and the degradation rate was found to be dependent on the DA of the polymers. In vivo degradation study further confirmed that gels formed from polymers with higher DA degraded faster. In vitro protein release demonstrated the feasibility to achieve lysozyme-mediated protein release from the gels and that the rate of protein release can be modulated by varying the DA. In vivo protein release study further confirmed the feasibility to achieve differential protein release by varying the DA. The feasibility to develop degradable enzymatically crosslinked GC hydrogels is demonstrated. Gels with a wide spectrum of degradation time ranging from less than a week and more than 6 weeks can be developed using this approach. The study also showed the feasibility to fine tune in vivo protein release by modulating HPP-GC acetylation. The hydrogel platform therefore holds significant promise as a protein delivery vehicle for various biomedical and regenerative engineering applications. Impact statement The study describes the feasibility to develop a novel enzyme sensitive biodegradable and injectable hydrogel, where in the in vivo degradation rate and protein release profile can be modulated over a wide range. The described hydrogel platform has the potential to develop into a clinically relevant injectable and tunable protein delivery vehicle for a wide range of biomedical applications.

Polymeric hydrogel as a vitreous substitute: current research, challenges, and future directions

Vitreoretinal surgery is an essential approach to treat proliferative diabetic vitreopathy, retinal detachment, retinal tear, ocular trauma, and macular holes. The removal of the natural vitreous and the replacement with substitutes are critical steps for retina reattachment. Vitreous substitutes including silicone oil (SiO), air, sulfur hexafluoride (SF₆), and perfluoropropane (C₃F₈), have been widely applied in clinical practice. However, these substitutes are reported to cause complications such as emulsification, high intraocular pressure, and lens opacification. Polymeric hydrogels are a kind of material with favorable physical, mechanical properties, and adaptable biocompatibility, thus being highly expected to be ideal vitreous substitutes. Despite years of research, very few polymeric hydrogels can be applied practically in the vitreous cavity. In this review, we focus on the development of polymeric natural-based hydrogels and synthetic hydrogels. Particularly, we pay attention to recent advances in the novel stimuli-response and self-assembly supramolecular hydrogels. Characterized by easy injectability and long residence time, this kind of hydrogel becomes the potentially promising candidates for ideal vitreous substitutes. Finally, we evaluate the current challenges and provide the future directions of vitreous substitutes.

Smart Hydrogels Meet Carbon Nanomaterials for New Frontiers in Medicine

Carbon nanomaterials include diverse structures and morphologies, such as fullerenes, nano-onions, nanodots, nanodiamonds, nanohorns, nanotubes, and graphene-based materials. They have attracted great interest in medicine for their high innovative potential, owing to their unique electronic and mechanical properties. In this review, we describe the most recent advancements in their inclusion in hydrogels to yield smart systems that can respond to a variety of stimuli. In particular, we focus on graphene and carbon nanotubes, for applications that span from sensing and wearable electronics to drug delivery and tissue engineering.

Lignin, lipid, protein, hyaluronic acid, starch, cellulose, gum, pectin, alginate and chitosan-based nanomaterials for cancer nanotherapy: Challenges and opportunities

Although nanotechnology-driven drug delivery systems are relatively new, they are rapidly evolving since the nanomaterials are deployed as effective means of diagnosis and delivery of assorted therapeutic agents to targeted intracellular sites in a controlled release manner. Nanomedicine and nanoparticulate drug delivery systems are rapidly developing as they play crucial roles in the development of therapeutic strategies for various types of cancer and malignancy. Nevertheless, high costs, associated toxicity and production of complexities are some of the critical barriers for their applications. Green nanomedicines have continually been improved as one of the viable approaches towards tumor drug delivery, thus making a notable impact on which considerably affect cancer treatment. In this regard, the utilization of natural and renewable feedstocks as a starting point for the fabrication of nanosystems can considerably contribute to the development of green nanomedicines. Nanostructures and biopolymers derived from natural and biorenewable resources such as proteins, lipids, lignin, hyaluronic acid, starch, cellulose, gum, pectin, alginate, and chitosan play vital roles in the development of cancer nanotherapy, imaging and management. This review uncovers recent investigations on diverse nanoarchitectures fabricated from natural and renewable feedstocks for the controlled/sustained and targeted drug/gene delivery systems against cancers including an outlook on some of the scientific challenges and opportunities in this field. Various important natural biopolymers and nanomaterials for cancer nanotherapy are covered and the scientific challenges and opportunities in this field are reviewed.

Important Roles of Oligo- and Polysaccharides against SARS-CoV-2: Recent Advances

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-initiated outbreak of COVID-19 has spread rapidly around the world, posing a huge threat to public health. Natural oligo- and polysaccharides with low toxicity, good sustainability, high biocompatibility, respectable safety, immune regulation, and antiviral activity can be employed as promising candidates for the prevention and inhibition of viral infections, especially COVID-19. Glycosaminoglycans, marine polysaccharides, terrestrial plant polysaccharides, and some others have exhibited potential antiviral activity against pathogenic viruses, in the format of polysaccharide-centered vaccine adjuvants, nano-based structures, drug conveyance platforms, etc. In this review, significant recent advancements pertaining to the antiviral applications of oligo- and polysaccharides against SARS-CoV-2 are highlighted, including important challenges and future perspectives.

Visible light-curable water-soluble chitosan derivative, chitosan hydrogel, and preparation method: a patent evaluation of US2019202998A1

Introduction: Water soluble polysaccharides are versatile structural materials that can be used for the design of biocompatible hydrogels and wet dressings in wound healing applications. Glycol chitosan (GC) is an example of a multifunctional water-soluble chitosan derivative that has inherent wound healing properties and reactive sites for chemical modification.Areas covered: United States (US) patent US2019202998A1 describes the preparation of a novel wound healing technology based on a three-dimensional (3D) crosslinked GC hydrogel (GCH) wet dressing, prepared via the synthesis of PEG1K-biscarboxylic acid-g-Glycol Chitosan-g-methacrylate using visible light induced photocrosslinking. The selected polymeric network enables the encapsulation of additional growth factors or bioactives on reactive sites. Wet dressings in US2019202998A1 were evaluated against a commercially available control for in vitro release, cytotoxicity, and in vivo wound healing ability in a preliminary mouse model, with the overall wound healing performance consistent with related GC-based hydrogels.Expert opinion: Comprehensive biocompatibility and antimicrobial testing of the hydrogel is not reported in US2019202998A1, and is recommended as further work to enable clinical applicability. The invention disclosed in US2019202998A1 can potentially be integrated with 3D bioprinting and sensor technology for the preparation of 'smart' hydrogel wound dressings, and is a potential area for future research.