Advances and trends of hydrogel therapy platform in localized tumor treatment: A review

A Comprehensive Review of Current Approaches in Bladder Cancer Treatment

Bladder cancer is one of the most common malignant tumors of the urinary system globally. It is also one of the most expensive cancers to manage, due to the need for extensive treatment and follow-ups that often involve invasive and costly procedures. Although there have been some improvements in treatment options, the quality of life they offer has not improved at the same rate as other cancers. Therefore, there is an urgent need to find new alternatives to ease the burden of bladder cancer on patients. Recent discoveries have opened new avenues for the diagnosis and management of bladder cancer even though the clinical approach has largely remained the same for years. The decline in bladder cancer-specific mortality in regions that promote social awareness of risk factors and reduction of carcinogenic exposure demonstrates the effectiveness of such measures. New agents have been approved for patients who have undergone radical cystectomy after Bacillus Calmette-Guérin failure. Current best practices for diagnosing and treating bladder cancer are presented in this review. The review discusses radiation therapy, photodynamic therapy, gene therapy, chemotherapy, and nanomedicine in relation to non muscle-invasive cancers and muscle-invasive bladder cancers, as well as systemic treatments.

Tumor Microenvironment-Responsive Polymer-Based RNA Delivery Systems for Cancer Treatment

Ribonucleic acid (RNA) therapeutics offer a broad prospect in cancer treatment. However, their successful application requires overcoming various physiological barriers to effectively deliver RNAs to the target sites. Currently, a number of RNA delivery systems based on polymeric nanoparticles are developed to overcome these barriers in RNA delivery. This work provides an overview of the existing RNA therapeutics for cancer gene therapy, and particularly summarizes those that are entering the clinical phase. This work then discusses the core features and latest research developments of tumor microenvironment-responsive polymer-based RNA delivery carriers which are designed based on the pathological characteristics of the tumor microenvironment. Finally, this work also proposes opportunities for the transformation of RNA therapies into cancer immunotherapy methods in clinical applications.

Recent Advancements of Nanomedicine in Breast Cancer Surgery

Breast cancer surgery plays a pivotal role in the multidisciplinary approaches. Surgical techniques and objectives are gradually shifting from tumor complete resection towards prolonging survival, improving cosmetic outcomes, and restoring the social and psychological well-being of patients. However, surgical treatment still faces challenges such as inadequate sensitivity in sentinel lymph node localization, the need to improve intraoperative tumor boundary localization imaging, postoperative scar healing, and the risk of recurrence, necessitating other adjunct measures for improvement. To address these challenges, specificity-optimized nanomedicines have been introduced into the surgical therapeutic landscape of breast cancer. In particular, this review involves starting with an overview of breast structure and the composition of the tumor microenvironment and then introducing the guiding principle and foundation for the design of nanomedicine. Moreover, we will take the order process of breast cancer surgery diagnosis and treatment as the starting point, and adaptively propose the roles and advantages of nanomedicine in addressing the corresponding issues. Furthermore, we also involved the prospects of utilizing advanced technological approaches. Overall, this review seeks to uncover the sophisticated design and strategies of nanomedicine from a clinical standpoint, address the challenges faced in surgical treatment, and provide insights into this subject matter.

Hydrogel Applications in the Diagnosis and Treatment of Glioblastoma

Glioblastoma multiforme (GBM), a common malignant neurological tumor, has boundaries indistinguishable from those of normal tissue, making complete surgical removal ineffective. The blood-brain barrier (BBB) further impedes the efficacy of radiotherapy and chemotherapy, leading to suboptimal treatment outcomes and a heightened probability of recurrence. Hydrogels offer multiple advantages for GBM diagnosis and treatment, including overcoming the BBB for improved drug delivery, controlled drug release for long-term efficacy, and enhanced relaxation properties of magnetic resonance imaging (MRI) contrast agents. Hydrogels, with their excellent biocompatibility and customizability, can mimic the in vivo microenvironment, support tumor cell culture, enable drug screening, and facilitate the study of tumor invasion and metastasis. This paper reviews the classification of hydrogels and recent research for the diagnosis and treatment of GBM, including their applications as cell culture platforms and drugs including imaging contrast agents carriers. The mechanisms of drug release from hydrogels and methods to monitor the activity of hydrogel-loaded drugs are also discussed. This review is intended to facilitate a more comprehensive understanding of the current state of GBM research. It offers insights into the design of integrated hydrogel-based GBM diagnosis and treatment with the objective of achieving the desired therapeutic effect and improving the prognosis of GBM.

Hydrogel local drug delivery systems for postsurgical management of tumors: Status Quo and perspectives

Surgery is one of the primary treatments for solid tumors. However, the incomplete resection of tumor cells and the immunosuppressive microenvironment make the issue of postsurgical tumor recurrence a great challenge. Furthermore, a wide range of requirements, including ensuring effective hemostasis, implementing prophylactic measures against infection, and promoting wound healing, were also raised in the postsurgical management of tumors. To fulfill these demands, multiple hydrogel local drug delivery systems (HLDDS) were developed recently. These HLDDS are expected to offer numerous advantages in the postsurgical management of tumors, such as achieving high local drug concentrations at the lesion, efficient delivery to surgical microcavities, mitigating systemic side effects, and addressing the diverse demand. Thus, in this review, a detailed discussion of the diverse demands of postsurgical management of tumors is provided. And the current publication trend on HLDDS in the postsurgical management of tumors is analyzed and discussed. Then, the applications of different types of HLDDS, in-situ HLDDS and non-in-situ HLDDS, in postsurgical management of tumors were introduced and summarized. Besides, the current problems and future perspectives are discussed. The review is expected to provide an overview of HLDDS in postsurgical management of tumors and promote their clinical application.

Crosslinked Biodegradable Hybrid Hydrogels Based on Poly(ethylene glycol) and Gelatin for Drug Controlled Release

A series of hybrid hydrogels of poly(ethylene glycol) (PEG) were synthesized using gelatin as a crosslinker and investigated for controlled delivery of the first-generation cephalosporin antibiotic, Cefazedone sodium (CFD). A commercially available 4-arm-PEG-OH was first modified to obtain four-arm-PEG-succinimidyl glutarate (4-arm-PEG-SG), which formed the gelatin-PEG composite hydrogels (SnNm) through crosslinking with gelatin. To regulate the drug delivery, SnNm hydrogels with various solid contents and crosslinking degrees were prepared. The effect of solid contents and crosslinking degrees on the thermal, mechanical, swelling, degradation, and drug release properties of the hydrogels were intensively investigated. The results revealed that increasing the crosslinking degree and solid content of SnNm could not only enhance the thermal stability, swelling ratio (SR), and compression resistance capacity of SnNm but also prolong the degradation and drug release times. The release kinetics of the SnNm hydrogels were found to follow the first-order model, suggesting that the transport rate of CFD within the matrix of hydrogels is proportional to the concentration of the drug where it is located. Specifically, S1N1-III showed 90% mass loss after 60 h of degradation and a sustained release duration of 72 h. The cytotoxicity assay using the MTT method revealed that cell viability rates of S1N1 were higher than 95%, indicating excellent cytocompatibility. This study offers new insights and methodologies for the development of hydrogels as biomedical composite materials.

Injectable Alginate-Based Hydrogels Encapsulating Engineered Endothelial Extracellular Vesicles for the Treatment of Critical Limb Ischemia

Critical limb ischemia (CLI) is a peripheral arterial disease resulting from chronic inflammation of vascular systems. Recent studies have shown that inhibiting macrophage inflammation has the potential to treat CLI, and extracellular vesicles (EVs) from endothelial cells can inhibit macrophage activation. However, the limited cell-targeting capabilities and rapid clearance of EVs from the injection site limit the in vivo application of the EVs. Here, we modified endothelial EVs with platelet membranes (pM/EVs) to boost the inhibition effects on macrophage inflammation and developed an injectable alginate-based collagen composite (ACC) hydrogel for localized delivery of pM/EVs (pM/EVs@ACC) for CLI treatment. We found that pM/EVs can effectively inhibit macrophage inflammation in vitro. Furthermore, pM/EVs@ACC treatment significantly promotes the recovery of limb functions, restoring the feet' blood supply and relieving inflammation. Our findings provide compelling evidence that the pM/EVs@ACC injectable system mediating delivery of pM/EVs is a promising strategy for CLI treatment.

A thermoresponsive chitosan-based in situ gel formulation incorporated with 5-FU loaded nanoerythrosomes for fibrosarcoma local chemotherapy

Local administration of drugs at tumor sites over an extended period of time shows potential as a promising approach for cancer treatment. In the present study, the temperature-induced phase transition of chitosan and poloxamer 407 is used to construct an injectable hydrogel encapsulating 5-FU-loaded nanoerythrosome (5-FU-NER-gel). The 5-FU-NERs were found to be spherical, measuring approximately 115 ± 20 nm in diameter and having a surface potential of -7.06 ± 0.4. The drug loading efficiency was approximately 40 %. In situ gel formation took place within 15 s when the gel was exposed to body temperature or subcutaneous injection. A sustained release profile was observed at pH 7.4 and 6.8, with a total 5-FU release of 76.57 ± 4.4 and 98.07 ± 6.31 in 24 h, respectively. MTT, Live/dead, and migration assays confirmed the cytocompatibility of the drug carrier and its effectiveness as a chemotherapeutic formulation. After in vivo antitumor assessment in a subcutaneous autograft model, it was demonstrated that tumor growth inhibition in 14 days was 90 %. Therefore, the obtained injectable chitosan-based hydrogel containing 5-FU-loaded nanoerythrosomes illustrated promising potential as a candidate for local and enhanced delivery of chemotherapeutics at the tumor site.

Advanced Hydrogels in Breast Cancer Therapy

Breast cancer is the most common malignancy among women and is the second leading cause of cancer-related death for women. Depending on the tumor grade and stage, breast cancer is primarily treated with surgery and antineoplastic therapy. Direct or indirect side effects, emotional trauma, and unpredictable outcomes accompany these traditional therapies, calling for therapies that could improve the overall treatment and recovery experiences of patients. Hydrogels, biomimetic materials with 3D network structures, have shown great promise for augmenting breast cancer therapy. Hydrogel implants can be made with adipogenic and angiogenic properties for tissue integration. 3D organoids of malignant breast tumors grown in hydrogels retain the physical and genetic characteristics of the native tumors, allowing for post-surgery recapitulation of the diseased tissues for precision medicine assessment of the responsiveness of patient-specific cancers to antineoplastic treatment. Hydrogels can also be used as carrier matrices for delivering chemotherapeutics and immunotherapeutics or as post-surgery prosthetic scaffolds. The hydrogel delivery systems could achieve localized and controlled medication release targeting the tumor site, enhancing efficacy and minimizing the adverse effects of therapeutic agents delivered by traditional procedures. This review aims to summarize the most recent advancements in hydrogel utilization for breast cancer post-surgery tissue reconstruction, tumor modeling, and therapy and discuss their limitations in clinical translation.

Recent research progress on tumour-specific responsive hydrogels

Most existing hydrogels, even recently developed injectable hydrogels that undergo a reversible sol-gel phase transition in response to external stimuli, are designed to gel immediately before or after implantation/injection to prevent the free diffusion of materials and drugs; however, the property of immediate gelation leads to a very weak tumour-targeting ability, limiting their application in anticancer therapy. Therefore, the development of tumour-specific responsive hydrogels for anticancer therapy is imperative because tumour-specific responses improve their tumour-targeting efficacy, increase therapeutic effects, and decrease toxicity and side effects. In this review, we introduce the following three types of tumour-responsive hydrogels: (1) hydrogels that gel specifically at the tumour site; (2) hydrogels that decompose specifically at the tumour site; and (3) hydrogels that react specifically with tumours. For each type, their compositions, the mechanisms of tumour-specific responsiveness and their applications in anticancer treatment are comprehensively discussed.

Alginate-Chitosan Biodegradable and Biocompatible Based Hydrogel for Breast Cancer Immunotherapy and Diagnosis: A Comprehensive Review

Breast cancer is the most common type of cancer and the second leading cause of cancer-related mortality in females. There are many side effects due to chemotherapy and traditional surgery, like fatigue, loss of appetite, skin irritation, and drug resistance to cancer cells. Immunotherapy has become a hopeful approach toward cancer treatment, generating long-lasting immune responses in malignant tumor patients. Recently, hydrogel has received more attention toward cancer therapy due to its specific characteristics, such as decreased toxicity, fewer side effects, and better biocompatibility drug delivery to the particular tumor location. Researchers globally reported various investigations on hydrogel research for tumor diagnosis. The hydrogel-based multilayer platform with controlled nanostructure has received more attention for its antitumor effect. Chitosan and alginate play a leading role in the formation of the cross-link in a hydrogel. Also, they help in the stability of the hydrogel. This review discusses the properties, preparation, biocompatibility, and bioavailability of various research and clinical approaches of the multipolymer hydrogel made of alginate and chitosan for breast cancer treatment. With a focus on cases of breast cancer and the recovery rate, there is a need to find out the role of hydrogel in drug delivery for breast cancer treatment.

Novel Drug Delivery Approaches for the Localized Treatment of Cervical Cancer

Cervical cancer (CC) is the fourth leading cancer type in females globally. Being an ailment of the birth canal, primitive treatment strategies, including surgery, radiation, or laser therapy, bring along the risk of infertility, neonate mortality, premature parturition, etc. Systemic chemotherapy led to systemic toxicity. Therefore, delivering a smaller cargo of therapeutics to the local site is more beneficial in terms of efficacy as well as safety. Due to the regeneration of cervicovaginal mucus, conventional dosage forms come with the limitations of leaking, the requirement of repeated administration, and compromised vaginal retention. Therefore, these days novel strategies are being investigated with the ability to combat the limitations of conventional formulations. Novel carriers can be engineered to manipulate bioadhesive properties and sustained release patterns can be obtained thus leading to the maintenance of actives at therapeutic level locally for a longer period. Other than the purpose of CC treatment, these delivery systems also have been designed as postoperative care where a certain dose of antitumor agent will be maintained in the cervix postsurgical removal of the tumor. Herein, the most explored localized delivery systems for the treatment of CC, namely, nanofibers, nanoparticles, in situ gel, liposome, and hydrogel, have been discussed in detail. These carriers have exceptional properties that have been further modified with the aid of a wide range of polymers in order to serve the required purpose of therapeutic effect, safety, and stability. Further, the safety of these delivery systems toward vital organs has also been discussed.

Development and characterization of magnetic hydrogels loaded with greenly synthesized iron-oxide nanoparticles conjugated with cisplatin

A novel approach was devised to address the challenges in delivering cisplatin (CIS) for lung cancer treatment. This involved the development of a non-invasive hydrogel delivery system, aiming to minimize side effects associated with its administration. Using carbopol 971 (CP) and chitosan (CH) at varying ratios, the hydrogels were prepared and loaded with eco-friendly iron oxide nanoparticles (IONPs) conjugated to CIS. The physical properties, yield, drug loading, and cytotoxicity against lung cancer cell lines (A549) were assessed, along with hydrogel rheological properties and in vitro drug diffusion. Hydrogel A1 that composed of 1:1 of CP:CH hydrogel loaded with 100 mg IONPs and 250 µg CIS demonstrated distinctive properties that indicate its suitability for potential delivery. The loaded greenly synthesized IONPs@CIS exhibited a particle size of 23.0 nm, polydispersity index of 0.47, yield of 71.6%, with 88.28% drug loading. They displayed significant cytotoxicity (61.7%) against lung cancer cell lines (A549), surpassing free CIS cytotoxicity (28.1%). Moreover, they demonstrated shear-thinning behaviour, viscoelastic properties, and Fickian drug release profile over 24 h (flux 2.34 µg/cm2/h, and permeability 0.31 cm/h).

Recent Biomaterial-Assisted Approaches for Immunotherapeutic Inhibition of Cancer Recurrence

Biomaterials possess distinctive properties, notably their ability to encapsulate active biological products while providing biocompatible support. The immune system plays a vital role in preventing cancer recurrence, and there is considerable demand for an effective strategy to prevent cancer recurrence, necessitating effective strategies to address this concern. This review elucidates crucial cellular signaling pathways in cancer recurrence. Furthermore, it underscores the potential of biomaterial-based tools in averting or inhibiting cancer recurrence by modulating the immune system. Diverse biomaterials, including hydrogels, particles, films, microneedles, etc., exhibit promising capabilities in mitigating cancer recurrence. These materials are compelling candidates for cancer immunotherapy, offering in situ immunostimulatory activity through transdermal, implantable, and injectable devices. They function by reshaping the tumor microenvironment and impeding tumor growth by reducing immunosuppression. Biomaterials facilitate alterations in biodistribution, release kinetics, and colocalization of immunostimulatory agents, enhancing the safety and efficacy of therapy. Additionally, how the method addresses the limitations of other therapeutic approaches is discussed.

Multifunctional Therapeutic Nanodiamond Hydrogels for Infected-Wound Healing and Cancer Therapy

Wound infection and tumor recurrence are the two main threats to cancer patients after surgery. Although researchers have developed new treatment systems to address the two significant challenges simultaneously, the potential side effects of the heavy-metal-ion-based treatment systems still severely limit their widespread application in therapy. In addition, the wounds from tumor removal compared with general operative wounds are more complex. The tumor wounds mainly exhibit more hemorrhage, larger trauma area, greater vulnerability to bacterial infection, and residual tumor cells. Therefore, a multifunctional treatment platform is urgently needed to integrate rapid hemostasis, sterilization, wound healing promotion, and antitumor functions. In this work, nanodiamonds (NDs), a material that has been well proven to have excellent biocompatibility, are added into a solution of acrylic-grafted chitosan (CEC) and oxidized hyaluronic acid (OHA) to construct a multifunctional treatment platform (CEC-OHA-NDs). The hydrogels exhibit rapid hemostasis, a wound-healing-promoting effect, excellent self-healing, and injectable abilities. Moreover, CEC-OHA-NDs can effectively eliminate bacteria and inhibit tumor proliferation by the warm photothermal effect of NDs under tissue-penetrable near-infrared laser irradiation (NIR) without cytotoxicity. Consequently, we adopt a simple and convenient strategy to construct a multifunctional treatment platform using carbon-based nanomaterials with excellent biocompatibility to promote the healing of infected wounds and to inhibit tumor cell proliferation simultaneously.

Research progress on hydrogel-based drug therapy in melanoma immunotherapy

Melanoma is one of the most aggressive skin tumors, and conventional treatment modalities are not effective in treating advanced melanoma. Although immunotherapy is an effective treatment for melanoma, it has disadvantages, such as a poor response rate and serious systemic immune-related toxic side effects. The main solution to this problem is the use of biological materials such as hydrogels to reduce these side effects and amplify the immune killing effect against tumor cells. Hydrogels have great advantages as local slow-release drug carriers, including the ability to deliver antitumor drugs directly to the tumor site, enhance the local drug concentration in tumor tissue, reduce systemic drug distribution and exhibit good degradability. Despite these advantages, there has been limited research on the application of hydrogels in melanoma treatment. Therefore, this article provides a comprehensive review of the potential application of hydrogels in melanoma immunotherapy. Hydrogels can serve as carriers for sustained drug delivery, enabling the targeted and localized delivery of drugs with minimal systemic side effects. This approach has the potential to improve the efficacy of immunotherapy for melanoma. Thus, the use of hydrogels as drug delivery vehicles for melanoma immunotherapy has great potential and warrants further exploration. [BMB Reports 2024; 57(2): 71-78].

Oxidized Dextran/Chitosan Hydrogel Engineered with Tetrasulfide-Bridged Silica Nanoparticles for Postsurgical Treatment

Tumor recurrence and wound microbial infection after tumor excision are serious threats to patients. Thus, the strategy to supply a sufficient and sustained release of cancer drugs and simultaneously engineer antibacterial properties and satisfactory mechanical strength is highly desired for tumor postsurgical treatment. Herein, A novel double-sensitive composite hydrogel embedded with tetrasulfide-bridged mesoporous silica (4S-MSNs) is developed. The incorporation of 4S-MSNs into oxidized dextran/chitosan hydrogel network, not only enhances the mechanical properties of hydrogels, but also can increase the specificity of drug with dual pH/redox sensitivity, thereby allowing more efficient and safer therapy. Besides, 4S-MSNs hydrogel preserves the favorable physicochemical properties of polysaccharide hydrogel, such as high hydrophilicity, satisfactory antibacterial activity, and excellent biocompatibility. Thus, the prepared 4S-MSNs hydrogel can be served as an efficient strategy for postsurgical bacterial infection and inhibition of tumor recurrence.

Injectable Zwitterionic Physical Hydrogel with Enhanced Chemodynamic Therapy and Tumor Microenvironment Remodeling Properties for Synergistic Anticancer Therapy

Surgical resection is the first-line therapy for breast cancer. However, residual tumor cells and the highly immunosuppressive tumor microenvironment (TME) continue to have a serious impact on tumor recurrence and metastasis postresection. Implantation of an in situ hydrogel system postresection has shown to be an effective treatment with great clinical potential. Herein, an injectable zwitterionic hydrogel system was developed for local drug delivery with enhanced immune activation and prevention of tumor recurrence. Driven by electrostatic interactions, poly(sulfobetaine methacrylate) (PSBMA) self-assembles into a hydrogel in saline, achieving low protein adsorption and tunable biodegradability. The chemotherapy drug doxorubicin (DOX) was loaded into copper peroxide nanoparticles (CuO2/DOX), which were coated with macrophage membranes to form tumor-targeting nanoparticles (M/CuO2/DOX). Next, M/CuO2/DOX and the stimulator of interferon genes (STING) agonist 2',3'-cGAMP were coloaded into PSBMA hydrogel (Gel@M/CuO2/DOX/STING). The hydrophilic STING agonist was first released by diffusion from hydrogel to activate the STING pathway and upregulate interferon (IFN) signaling related genes, remodeling the immunosuppressive TME. Then, M/CuO2/DOX targeted the residual tumor cells, combining with DOX-induced DNA damage, immunogenic tumor cell death, and copper death. Hence, this work combines chemodynamic therapy with STING pathway activation in TME, encouraging residual tumor cell death, promoting the maturation of dendritic cells, enhancing tumor-specific CD8+ T cell infiltration, and preventing postoperative recurrence and metastasis.

Engineered cyclodextrin-based supramolecular hydrogels for biomedical applications

Cyclodextrin (CD)-based supramolecular hydrogels are polymer network systems with the ability to rapidly form reversible three-dimensional porous structures through multiple cross-linking methods, offering potential applications in drug delivery. Although CD-based supramolecular hydrogels have been increasingly used in a wide range of applications in recent years, a comprehensive description of their structure, mechanical property modulation, drug loading, delivery, and applications in biomedical fields from a cross-linking perspective is lacking. To provide a comprehensive overview of CD-based supramolecular hydrogels, this review systematically describes their design, regulation of mechanical properties, modes of drug loading and release, and their roles in various biomedical fields, particularly oncology, wound dressing, bone repair, and myocardial tissue engineering. Additionally, this review provides a rational discussion on the current challenges and prospects of CD-based supramolecular hydrogels, which can provide ideas for the rapid development of CD-based hydrogels and foster their translation from the laboratory to clinical medicine.

Multifunctional Photothermal Hydrogel in the Second Near-Infrared Window for Localized Tumor Therapy

A copper selenide-embedded gellan gum hydrogel (Cu2-xSe@GG) is designed as an "all-in-one" antitumor agent. The obtained nanocomposite hydrogel exhibits strong near-infrared light absorption and high photothermal conversion efficiency in both the NIR-I and NIR-II biowindows. The photothermal conversion efficiency achieves 58.8% under the irradiation of 0.75 W/cm2 with a 1064 nm laser. Furthermore, the nanocomposite hydrogel has catalase- and peroxidase-mimicking activities, which could alter the tumor microenvironment by reducing hypoxia and/or increasing the production of reactive oxygen species. Moreover, the multifunctional Cu2-xSe@GG nanocomposite hydrogel can also be used as an immune agonist resiquimod (R848) carrier to promote immune regulation and enhance the therapeutic effect. The single-syringe R848/Cu2-xSe@GG treatment achieves synergetic photothermal immunotherapy, showing 97.4% of tumor regression rate from an initial large tumor of 300 mm3.

Application of advanced biomaterials in photothermal therapy for malignant bone tumors

Malignant bone tumors are characterized by severe disability rate, mortality rate, and heavy recurrence rate owing to the complex pathogenesis and insidious disease progression, which seriously affect the terminal quality of patients' lives. Photothermal therapy (PTT) has emerged as an attractive adjunctive treatment offering prominent hyperthermal therapeutic effects to enhance the effectiveness of surgical treatment and avoid recurrence. Simultaneously, various advanced biomaterials with photothermal capacity are currently created to address malignant bone tumors, performing distinctive biological functions, including nanomaterials, bioceramics (BC), polymers, and hydrogels et al. Furthermore, PTT-related combination therapeutic strategies can provide more significant curative benefits by reducing drug toxicity, improving tumor-killing efficiency, stimulating anti-cancer immunity, and improving immune sensitivity relative to monotherapy, even in complex tumor microenvironments (TME). This review summarizes the current advanced biomaterials applicable in PTT and relevant combination therapies on malignant bone tumors for the first time. The multiple choices of advanced biomaterials, treatment methods, and new prospects for future research in treating malignant bone tumors with PTT are generalized to provide guidance. Malignant bone tumors seriously affect the terminal quality of patients' lives. Photothermal therapy (PTT) has emerged as an attractive adjunctive treatment enhancing the effectiveness of surgical treatment and avoiding recurrence. In this review, advanced biomaterials applicable in the PTT of malignant bone tumors and their distinctive biological functions are comprehensively summarized for the first time. Simultaneously, multiple PTT-related combination therapeutic strategies are classified to optimize practical clinical issues, contributing to the selection of biomaterials, therapeutic alternatives, and research perspectives for the adjuvant treatment of malignant bone tumors with PTT in the future.

Tissue adhesive indocyanine green-locking granular gel-mediated photothermal therapy combined with checkpoint inhibitor for preventing postsurgical recurrence and metastasis of colorectal cancer

Developing effective therapy to inhibit postoperative recurrence and metastasis of colorectal cancer (CRC) is challenging and significant to reduce mortality and morbidity. Here, a granular hydrogel, assembled from gelatin microgels by dialdehyde starch and interpenetrated with in situ polymerized poly(sulfobetaine methacrylate-co-N-isopropylacrylamide) (P(SBMA-co-NIPAM)), is prepared to load and lock Food and Drug Administration (FDA)-approved indocyanine green (ICG) with definite photothermal function and biosafety for photothermal therapy (PTT) combining with checkpoint inhibitor. The presence of P(SBMA-co-NIPAM) endows granular hydrogel with high retention to water-soluble ICG, preventing easy diffusion and rapid scavenging of ICG. The ICG-locking granular hydrogel can be spread and adhered onto the surgery site at wet state in vivo, exerting a persistent and stable PTT effect. Combined with αPD-L1 treatment, ICG-locking granular hydrogel-mediated PTT can eradicate postsurgery residual and metastatic tumors, and prevent long-term tumor recurrence. Further mechanistic studies indicate that combination treatment effectively promotes dendritic cells maturation in lymph nodes, enhances the number and infiltration of CD8+ T and CD4+ T cells in tumor tissue, and improves memory T cell number in spleen, thus activating the antitumor immune response. Overall, ICG-locking gel-mediated PTT is expected to exhibit broad clinical applications in postoperative treatment of cancers, like CRC.

Gel/hydrogel-based in situ biomaterial platforms for cancer postoperative treatment and recovery

Tumor surgical resection is the major strategy for cancer treatment. Meanwhile, perioperative treatment especially the postoperative adjuvant anticancer strategies play essential roles in satisfying therapeutic results and rapid recovery. Postoperative tumor recurrence, metastasis, bleeding, inter-tissue adhesion, infection, and delayed wound healing are vital risks that could lead to poor prognosis or even treatment failure. Therefore, methods targeting these postoperative complications are in desperate need. In situ biomaterial-based drug delivery platforms are promising candidates for postoperative treatment and recovery, resulting from their excellent properties including good biocompatibility, adaptive shape, limited systemic effect, designable function, and easy drug loading. In this review, we focus on introducing the gel/hydrogel-based in situ biomaterial platforms involving their properties, advantages, and synthesis procedures. Based on the loaded contents in the gel/hydrogel such as anticancer drugs, immunologic agents, cell components, and multifunctional nanoparticles, we further discuss the applications of the in situ platforms for postoperative tumor recurrence and metastasis inhibition. Finally, other functions aiming at fast postoperative recovery were introduced, including hemostasis, antibacterial infection, adhesion prevention, tissue repair, and wound healing. In conclusion, gel/hydrogel is a developing and promising platform for postoperative treatment, exhibiting gratifying therapeutic effects and inconspicuous toxicity to normal tissues, which deserves further research and exploration.

Recent progress in tannic acid based approaches as a natural polyphenolic biomaterial for cancer therapy: A review

Significant advancements have been noticed in cancer therapy for decades. Despite this, there are still many critical challenges ahead, including multidrug resistance, drug instability, and side effects. To overcome obstacles of these problems, various types of materials in biomedical research have been explored. Chief among them, the applications of natural compounds have grown rapidly due to their superb biological activities. Natural compounds, especially polyphenolic compounds, play a positive and great role in cancer therapy. Tannic acid (TA), one of the most famous polyphenols, has attracted widespread attention in the field of cancer treatment with unique structural, physicochemical, pharmaceutical, anticancer, antiviral, antioxidant and other strong biological features. This review concentrated on the basic structure along with the important role of TA in tuning oncological signal pathways firstly, and then focused on the use of TA in chemotherapy and preparation of delivery systems including nanoparticles and hydrogels for cancer therapy. Besides, the application of TA/Fe3+ complex coating in photothermal therapy, chemodynamic therapy, combined therapy and theranostics is discussed.

Local Sustained Chemotherapy of Pancreatic Cancer Using Endoscopic Ultrasound-Guided Injection of Biodegradable Thermo-Sensitive Hydrogel

Purpose

Endoscopic ultrasound-guided fine-needle injection (EUS-FNI) offers a promising minimally invasive approach for locally targeted management of advanced pancreatic cancer. However, the efficacy is limited due to the rapid plasma clearance of chemotherapeutic agents. Injectable hydrogels can form drug release depots, which provide a feasible solution for optimizing targeted chemotherapy through EUS-FNI.

Methods

A drug delivery system was developed, consisting of gemcitabine (GEM) and thermo-sensitive hydrogel (PLGA-PEG-PLGA, PPP). The injectability, gel formation ability, biocompatibility and sustained drug delivery properties of PPP hydrogel were verified in vitro and in vivo. The effects of GEM/PPP hydrogel on cell proliferation, invasion, metastasis, and apoptosis were explored through co-culturing with PANC-1 cells. The therapeutic effects of GEM/PPP hydrogel on xenograft mice were compared with those of GEM, ethanol and polidocanol using the precisely targeted EUS-FNI technology. Tumor sections were examined by H&E, Ki-67, and TUNEL staining.

Results

GEM/PPP hydrogel exhibited excellent injectability, biocompatibility, and the capability of sustained drug delivery for up to 7 days by forming a gel triggered by body temperature. It demonstrated the best therapeutic effects, significantly reducing proliferation, invasion and migration of PANC-1 cells while promoting apoptosis. After precise injection using EUS-FNI technology, GEM/PPP hydrogel resulted in a reduction of tumor weight by up to 75.96% and extending the survival period by 14.4 days with negligible adverse effects. Pathological examination revealed no systemic toxicity and significant apoptosis and minimal proliferation as well.

Conclusion

The combination of GEM/PPP hydrogel and EUS-FNI technology provides an optimal approach of precise chemotherapy for pancreatic cancer, builds a bridge for clinical translation of basic research, and brings great hope for innovation of minimally invasive treatment modalities. The first-hand EUS image data obtained in this study also serves as a crucial reference for future clinical trials.

A Review of the Mechanism, Properties, and Applications of Hydrogels Prepared by Enzymatic Cross-linking

Hydrogels, as biological materials, are widely used in food, tissue engineering, and biomedical applications. Nevertheless, many issues remain in the preparation of hydrogels by physical and chemical methods, such as low bioaffinity, weak mechanical properties, and unstable structures, which also limit their applications in other fields. However, the enzymatic cross-linking method has the advantages of high catalytic efficiency, mild reaction conditions, and the presence of nontoxic substances. In this review, we evaluated the chemical, physical, and biological methods of preparing hydrogels and introduced three common cross-linking enzymes and their principles for preparing hydrogels. This review introduced the applications and properties of hydrogels prepared by the enzymatic method and also provided some suggestions regarding the current situation and future development of hydrogels prepared by enzymatic cross-linking.

Curcumin in the treatment of liver cancer: From mechanisms of action to nanoformulations

Liver cancer is the sixth most prevalent cancer and ranks third in cancer-related death, after lung and colorectal cancer. Various natural products have been discovered as alternatives to conventional cancer therapy strategies, including radiotherapy, chemotherapy, and surgery. Curcumin (CUR) with antiinflammatory, antioxidant, and antitumor activities has been associated with therapeutic benefits against various cancers. It can regulate multiple signaling pathways, such as PI3K/Akt, Wnt/β-catenin, JAK/STAT, p53, MAPKs, and NF-ĸB, which are involved in cancer cell proliferation, metastasis, apoptosis, angiogenesis, and autophagy. Due to its rapid metabolism, poor oral bioavailability, and low solubility in water, CUR application in clinical practices is restricted. To overcome these limitations, nanotechnology-based delivery systems have been applied to use CUR nanoformulations with added benefits, such as reducing toxicity, improving cellular uptake, and targeting tumor sites. Besides the anticancer activities of CUR in combating various cancers, especially liver cancer, here we focused on the CUR nanoformulations, such as micelles, liposomes, polymeric, metal, and solid lipid nanoparticles, and others, in the treatment of liver cancer.

Injectable carboxymethyl chitosan-based hydrogel for simultaneous anti-tumor recurrence and anti-bacterial applications

The postoperative recurrence has adversely affected the treatment of tumors. Besides, the potential bacterial infection at the wound site may lead to a series of tissue necrosis. Here, we developed an injectable γ-polyglutamic acid/carboxymethyl chitosan/polydopamine hydrogel (PCP) for simultaneously reducing the postoperative infection and preventing the tumor recurrence. On the one hand, the aqueous solution of carboxymethyl chitosan oxidized the dopamine into polydopamine; on the other, the carboxymethyl chitosan was cross-linked with the activated γ-polyglutamic acid to form a hydrogel. After local implantation, the PCP hydrogel effectively killed tumor cells and bacteria under 808 nm laser irradiation. In addition, carboxymethyl chitosan rendered the hydrogel with anti-bacterial properties as well as anti-tumor efficiencies. The anti-tumor recurrence and anti-bacterial efficiencies of PCP hydrogel were proved on a tumor-removed mouse model and a Staphylococcus aureus-infected mouse model, respectively. Moreover, the hydrogel has the advantages of good biocompatibility and simple preparation, and thus has potential application prospects in the prevention of tumor recurrence and wound bacterial infection.

Recent progress of hydrogel-based local drug delivery systems for postoperative radiotherapy

Surgical resection and postoperative radiotherapy remained the most common therapeutic modalities for malignant tumors. However, tumor recurrence after receiving such combination is difficult to be avoided because of high invasiveness and radiation resistance of cancer cells during long-term therapy. Hydrogels, as novel local drug delivery systems, presented excellent biocompatibility, high drug loading capacity and sustained drug release property. Compared with conventional drug formulations, hydrogels are able to be administered intraoperatively and directly release the entrapped therapeutic agents to the unresectable tumor sites. Therefore, hydrogel-based local drug delivery systems have their unique advantages especially in sensitizing postoperative radiotherapy. In this context, classification and biological properties of hydrogels were firstly introduced. Then, recent progress and application of hydrogels for postoperative radiotherapy were summarized. Finally, the prospects and challenges of hydrogels in postoperative radiotherapy were discussed.

A Sustainable Solution to Skin Diseases: Ecofriendly Transdermal Patches

Skin is the largest epithelial surface of the human body, with a surface area of 2 m2 for the average adult human. Being an external organ, it is susceptible to more than 3000 potential skin diseases, including injury, inflammation, microbial and viral infections, and skin cancer. Due to its nature, it offers a large accessible site for administrating several medications against these diseases. The dermal and transdermal delivery of such medications are often ensured by utilizing dermal/transdermal patches or microneedles made of biocompatible and biodegradable materials. These tools provide controlled delivery of drugs to the site of action in a rapid and therapeutically effective manner with enhanced diffusivity and minimal side effects. Regrettably, they are usually fabricated using synthetic materials with possible harmful environmental effects. Manufacturing such tools using green synthesis routes and raw materials is hence essential for both ecological and economic sustainability. In this review, natural materials including chitosan/chitin, alginate, keratin, gelatin, cellulose, hyaluronic acid, pectin, and collagen utilized in designing ecofriendly patches will be explored. Their implementation in wound healing, skin cancer, inflammations, and infections will be discussed, and the significance of these studies will be evaluated with future perspectives.

The recent advancement in the PLGA-based thermo-sensitive hydrogel for smart drug delivery

To date, hydrogels have opened new prospects for potential applications for drug delivery. The thermo-sensitive hydrogels have the great potential to provide more effective and controllable release of therapeutic/bioactive agents in response to changes in temperature. PLGA is a safe FDA-approved copolymer with good biocompatibility and biodegradability. Recently, PLGA-based formulation have attracted a lot of interest for thermo-sensitive hydrogels. Thermo-sensitive PLGA-based hydrogels provide the delivery system with good spatial and temporal control, and have been widely applied in drug delivery. This review is focused on the recent progression of the thermo-sensitive and biodegradable PLGA-based hydrogels that have been reported for smart drug delivery to the different organs. Eventually, future perspectives and challenges of thermo-sensitive PLGA-based hydrogels are discussed briefly.

Hydrogel systems for targeted cancer therapy

When hydrogel materials with excellent biocompatibility and biodegradability are used as excellent new drug carriers in the treatment of cancer, they confer the following three advantages. First, hydrogel materials can be used as a precise and controlled drug release systems, which can continuously and sequentially release chemotherapeutic drugs, radionuclides, immunosuppressants, hyperthermia agents, phototherapy agents and other substances and are widely used in the treatment of cancer through radiotherapy, chemotherapy, immunotherapy, hyperthermia, photodynamic therapy and photothermal therapy. Second, hydrogel materials have multiple sizes and multiple delivery routes, which can be targeted to different locations and types of cancer. This greatly improves the targeting of drugs, thereby reducing the dose of drugs and improving treatment effectiveness. Finally, hydrogel can intelligently respond to environmental changes according to internal and external environmental stimuli so that anti-cancer active substances can be remotely controlled and released on demand. Combining the abovementioned advantages, hydrogel materials have transformed into a hit in the field of cancer treatment, bringing hope to further increase the survival rate and quality of life of patients with cancer.

Polysaccharide-based hydrogel with photothermal effect for accelerating wound healing

Polysaccharide-based hydrogel has excellent biochemical function, abundant sources, good biocompatibility and other advantages, and has a broad application prospect in biomedical fields, especially in the field of wound healing. With its inherent high specificity and low invasive burden, photothermal therapy has shown great application prospect in preventing wound infection and promoting wound healing. Combining polysaccharide-based hydrogel with photothermal therapy (PTT), multifunctional hydrogel with photothermal, bactericidal, anti-inflammatory and tissue regeneration functions can be designed, so as to achieve better therapeutic effect. This review first focuses on the basic principles of hydrogel and PTT, and the types of polysaccharides that can be used to design hydrogels. In addition, according to the different materials that produce photothermal effects, the design considerations of several representative polysaccharide-based hydrogels are emphatically introduced. Finally, the challenges faced by polysaccharide-based hydrogels with photothermal properties are discussed, and the future prospects of this field are put forward.

Advances in Antitumor Nano-Drug Delivery Systems of 10-Hydroxycamptothecin

10-Hydroxycamptothecin (HCPT) is a natural plant alkaloid from Camptotheca that shows potent antitumor activity by targeting intracellular topoisomerase I. However, factors such as instability of the lactone ring and insolubility in water have limited the clinical application of this drug. In recent years, unprecedented advances in biomedical nanotechnology have facilitated the development of nano drug delivery systems. It has been found that nanomedicine can significantly improve the stability and water solubility of HCPT. NanoMedicines with different diagnostic and therapeutic functions have been developed to significantly improve the anticancer effect of HCPT. In this paper, we collected reports on HCPT nanomedicines against tumors in the past decade. Based on current research advances, we dissected the current status and limitations of HCPT nanomedicines development and looked forward to future research directions.

Progress of Nanomaterials-Based Photothermal Therapy for Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is one of the top 15 most prevalent cancers worldwide. However, the current treatment models for OSCC (e.g., surgery, chemotherapy, radiotherapy, and combination therapy) present several limitations: damage to adjacent healthy tissue, possible recurrence, low efficiency, and severe side effects. In this context, nanomaterial-based photothermal therapy (PTT) has attracted extensive research attention. This paper reviews the latest progress in the application of biological nanomaterials for PTT in OSCC. We divide photothermal nanomaterials into four categories (noble metal nanomaterials, carbon-based nanomaterials, metal compounds, and organic nanomaterials) and introduce each category in detail. We also mention in detail the drug delivery systems for PTT of OSCC and briefly summarize the applications of hydrogels, liposomes, and micelles. Finally, we note the challenges faced by the clinical application of PTT nanomaterials and the possibility of further improvement, providing direction for the future research of PTT in OSCC treatment.

Protocatechuic Acid-Based Supramolecular Hydrogel Targets SerpinB9 to Achieve Local Chemotherapy for OSCC

Protocatechuic acid (PCA) is a natural phenolic acid present in daily vegetables and fruits. Notably, PCA was demonstrated to inhibit the biological function of SerpinB9 (Sb9) and exhibit an excellent antitumor effect, showing great potential in cancer treatment. However, the short half-life time limits PCA's wide application against cancers. To overcome this shortage of PCA, we integrated PCA and another natural product with strong self-assembling properties, isoguanosine (isoG), to develop a novel multifunctional supramolecular hydrogel with good biocompatibility and injectability, which remarkably lengthens the releasing time of PCA and exerts considerable anticancer effects in vitro and in vivo. Besides, we surprisingly found that PCA could not only target Sb9 but also restrain cancer development through activating the JNK/P38 pathway, decreasing the ROS level, and repairing cancer stemness. In all, our results demonstrate that this PCA-based hydrogel could act as a multifunctional hydrogel system equipped with considerable anticancer effects, providing potential local administration integrating with targeted therapy and chemotherapy in one simple modality.

Current Researches on Nanodrug Delivery Systems in Bladder Cancer Intravesical Chemotherapy

Bladder cancer is one of the most common malignant tumors in urinary system. Intravesical chemotherapy is a common adjuvant therapy after transurethral resection of bladder tumors. However, it has several disadvantages such as low drug penetration rate, short residence time, unsustainable action and inability to release slowly, thus new drug delivery and new modalities in delivery carriers need to be continuously explored. Nano-drug delivery system is a novel way in treatment for bladder cancer that can increase the absorption rate and prolong the duration of drug, as well as sustain the action by controlling drug release. Currently, nano-drug delivery carriers mainly included liposomes, polymers, and inorganic materials. In this paper, we reveal current researches in nano-drug delivery system in bladder cancer intravesical chemotherapy by describing the applications and defects of liposomes, polymers and inorganic material nanocarriers, and provide a basis for the improvement of intravesical chemotherapy drugs in bladder cancer.

Hydrogels for Antitumor and Antibacterial Therapy

As a highly absorbent and hydrophobic material with a three-dimensional network structure, hydrogels are widely used in biomedical fields for their excellent biocompatibility, low immunogenicity, adjustable physicochemical properties, ability to encapsulate a variety of drugs, controllability, and degradability. Hydrogels can be used not only for wound dressings and tissue repair, but also as drug carriers for the treatment of tumors. As multifunctional hydrogels are the focus for many researchers, this review focuses on hydrogels for antitumor therapy, hydrogels for antibacterial therapy, and hydrogels for co-use in tumor therapy and bacterial infection. We highlighted the advantages and representative applications of hydrogels in these fields and also outlined the shortages and future orientations of this useful tool, which might give inspirations for future studies.

Hydrogels and Hydrogel Nanocomposites: Enhancing Healthcare through Human and Environmental Treatment

Humans are constantly exposed to exogenous chemicals throughout their life, which can lead to a multitude of negative health impacts. Advanced materials can play a key role in preventing or mitigating these impacts through a wide variety of applications. The tunable properties of hydrogels and hydrogel nanocomposites (e.g., swelling behavior, biocompatibility, stimuli responsiveness, functionality, etc.) have deemed them ideal platforms for removal of environmental contaminants, detoxification, and reduction of body burden from exogenous chemical exposures for prevention of disease initiation, and advanced treatment of chronic diseases, including cancer, diabetes, and cardiovascular disease. In this review, three main junctures where the use of hydrogel and hydrogel nanocomposite materials can intervene to positively impact human health are highlighted: 1) preventing exposures to environmental contaminants, 2) prophylactic treatments to prevent chronic disease initiation, and 3) treating chronic diseases after they have developed.

Injectable Hydrogel as a Unique Platform for Antitumor Therapy Targeting Immunosuppressive Tumor Microenvironment

Cancer immunotherapy can boost the immune response of patients to eliminate tumor cells and suppress tumor metastasis and recurrence. However, immunotherapy resistance and the occurrence of severe immune-related adverse effects are clinical challenges that remain to be addressed. The tumor microenvironment plays a crucial role in the therapeutic efficacy of cancer immunotherapy. Injectable hydrogels have emerged as powerful drug delivery platforms offering good biocompatibility and biodegradability, minimal invasion, convenient synthesis, versatility, high drug-loading capacity, controlled drug release, and low toxicity. In this review, we summarize the application of injectable hydrogels as a unique platform for targeting the immunosuppressive tumor microenvironment.

An Injectable In Situ Depot-Forming Lipidic Lyotropic Liquid Crystal System for Localized Intratumoral Drug Delivery

To address the need for localized chemotherapy against unresectable solid tumors, an injectable in situ depot-forming lipidic lyotropic liquid crystal system (L3CS) is explored that can provide spatiotemporal control over drug delivery. Although liquid crystals have been studied extensively before but their application as an injectable intratumoral depot system for locoregional chemotherapy has not been explored yet. The developed L3CS in the present study is a low-viscosity injectable fluid having a lamellar phase, which transforms into a hexagonal mesophase depot system on subcutaneous or intratumoral injection. The transformed depot system can be preprogrammed to provide tailored drug release intratumorally, over a period of one week to one month. To establish the efficacy of the developed L3CS, doxorubicin is used as a model drug. The drug release mechanism is studied in detail both in vitro and in vivo, and the efficacy of the developed system is investigated in the murine 4T1 tumor model. The direct intratumoral injection of the L3CS provided localized delivery of doxorubicin inside the tumor and restricted its access within the tumor only for a sustained period of time. This led to an over 10-fold reduction in tumor burden, reduced cardiotoxicity, and a significant increase in the median survival rate, compared to the control group. The developed L3CS thus provides an efficient strategy for localized chemotherapy against unresectable solid tumors with a great degree of spatial and temporal control over drug delivery.

Hybrid in situ- forming injectable hydrogels for local cancer therapy

Injectable in situ forming hydrogels are amongst the efficient local drug delivery systems for cancer therapy. Providing a 3D hydrogel network within the target tissue capable of sustained release of the chemotherapeutics made them attractive candidates for increasing the therapeutic index. Remarkable swelling properties, mechanical strength, biocompatibility, wide composition variety and tunable polymeric moieties have led to preparation of injectable hydrogels which also could be used as cavity adaptive chemotherapeutic-loaded implants to prevent post -surgical cancer recurrence. Implementation of various polymers, nanoparticles, peptide and proteins and different crosslinking chemistry facilitated the fabrication of hybrid hydrogels with favorable characteristics such as stimuli sensitive platforms or multifunctional systems. In the current review, we focused on design and fabrication strategies of injectable in situ forming hydrogels and summarized recent hybrid hydrogels used for local cancer therapy.

Drug Delivery Based on Stimuli-Responsive Injectable Hydrogels for Breast Cancer Therapy: A Review

Breast cancer is the most common and biggest health threat for women. There is an urgent need to develop novel breast cancer therapies to overcome the shortcomings of conventional surgery and chemotherapy, which include poor drug efficiency, damage to normal tissues, and increased side effects. Drug delivery systems based on injectable hydrogels have recently gained remarkable attention, as they offer encouraging solutions for localized, targeted, and controlled drug release to the tumor site. Such systems have great potential for improving drug efficiency and reducing the side effects caused by long-term exposure to chemotherapy. The present review aims to provide a critical analysis of the latest developments in the application of drug delivery systems using stimuli-responsive injectable hydrogels for breast cancer treatment. The focus is on discussing how such hydrogel systems enhance treatment efficacy and incorporate multiple breast cancer therapies into one system, in response to multiple stimuli, including temperature, pH, photo-, magnetic field, and glutathione. The present work also features a brief outline of the recent progress in the use of tough hydrogels. As the breast undergoes significant physical stress and movement during sporting and daily activities, it is important for drug delivery hydrogels to have sufficient mechanical toughness to maintain structural integrity for a desired period of time.

Nanocatalyst-Mediated Chemodynamic Tumor Therapy

Traditional tumor treatments, including chemotherapy, radiotherapy, photodynamic therapy, and photothermal therapy, are developed and used to treat different types of cancer. Recently, chemodynamic therapy (CDT) has been emerged as a novel cancer therapeutic strategy. CDT utilizes Fenton or Fenton-like reaction to generate highly cytotoxic hydroxyl radicals (•OH) from endogenous hydrogen peroxide (H₂ O₂ ) to kill cancer cells, which displays promising therapeutic potentials for tumor treatment. However, the low catalytic efficiency and off-target side effects of Fenton reaction limit the biomedical application of CDT. In this regard, various strategies are implemented to potentiate CDT against tumor, including retrofitting the tumor microenvironment (e.g., increasing H₂ O₂ level, decreasing reductive substances, and reducing pH), enhancing the catalytic efficiency of nanocatalysts, and other strategies. This review aims to summarize the development of CDT and summarize these recent progresses of nanocatalyst-mediated CDT for antitumor application. The future development trend and challenges of CDT are also discussed.

Mechanical Studies of the Third Dimension in Cancer: From 2D to 3D Model

From the development of self-aggregating, scaffold-free multicellular spheroids to the inclusion of scaffold systems, 3D models have progressively increased in complexity to better mimic native tissues. The inclusion of a third dimension in cancer models allows researchers to zoom out from a significant but limited cancer cell research approach to a wider investigation of the tumor microenvironment. This model can include multiple cell types and many elements from the extracellular matrix (ECM), which provides mechanical support for the tissue, mediates cell-microenvironment interactions, and plays a key role in cancer cell invasion. Both biochemical and biophysical signals from the extracellular space strongly influence cell fate, the epigenetic landscape, and gene expression. Specifically, a detailed mechanistic understanding of tumor cell-ECM interactions, especially during cancer invasion, is lacking. In this review, we focus on the latest achievements in the study of ECM biomechanics and mechanosensing in cancer on 3D scaffold-based and scaffold-free models, focusing on each platform's level of complexity, up-to-date mechanical tests performed, limitations, and potential for further improvements.

Oxidation triggered formation of polydopamine-modified carboxymethyl cellulose hydrogel for anti-recurrence of tumor

In this research, a hydrogel that combined the tumor photodynamic therapy (PDT) and photothermal therapy (PTT) ability was designed, using dopamine-modified sodium carboxymethyl cellulose (CMC-DA) as the matrix and Chlorin e6 (Ce6) as the photosensitizer. The gel formation was initiated by adding the oxidizing agent sodium periodate (NaIO₄) to the CMC-DA solution, during which the dopamine was simultaneously oxidized to polydopamine (PDA) and NaIO₄ was reduced to sodium iodide (NaI). The formed NaI was encapsulated in the hydrogel and endowed the hydrogel with computerized tomography (CT) imaging ability to monitor the hydrogel degradation and the tumor therapy process. Moreover, the photosensitizer Ce6 can be loaded by the gel system via directly soaking the hydrogel in the Ce6 solution. Under the near-infrared light irradiation, Ce6 can produce cytotoxic reactive oxygen species and the PDA can produce heat to trigger the tumor PDT and PTT respectively to eradicate the tumor recurrence. In general, the designed hydrogel is biocompatible and biodegradable, has a good photothermal conversion, drug loading and CT imaging ability, which laid the foundation for the rational design of biodegradable hydrogels for multifunctional applications.

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.

A Review on Hydrogels with Photothermal Effect in Wound Healing and Bone Tissue Engineering

Photothermal treatment (PTT) is a promising strategy to deal with multidrug-resistant bacteria infection and promote tissue regeneration. Previous studies demonstrated that hyperthermia can effectively inhibit the growth of bacteria, whereas mild heat can promote cell proliferation, further accelerating wound healing and bone regeneration. Especially, hydrogels with photothermal properties could achieve remotely controlled drug release. In this review, we introduce a photothermal agent hybrid in hydrogels for a photothermal effect. We also summarize the potential mechanisms of photothermal hydrogels regarding antibacterial action, angiogenesis, and osteogenesis. Furthermore, recent developments in photothermal hydrogels in wound healing and bone regeneration applications are introduced. Finally, future application of photothermal hydrogels is discussed. Hydrogels with photothermal effects provide a new direction for wound healing and bone regeneration, and this review will give a reference for the tissue engineering.

Biomaterial-based strategies for maxillofacial tumour therapy and bone defect regeneration

Issues caused by maxillofacial tumours involve not only dealing with tumours but also repairing jaw bone defects. In traditional tumour therapy, the systemic toxicity of chemotherapeutic drugs, invasive surgical resection, intractable tumour recurrence, and metastasis are major threats to the patients' lives in the clinic. Fortunately, biomaterial-based intervention can improve the efficiency of tumour treatment and decrease the possibility of recurrence and metastasis, suggesting new promising antitumour therapies. In addition, maxillofacial bone tissue defects caused by tumours and their treatment can negatively affect the physiological and psychological health of patients, and investment in treatment can result in a multitude of burdens to society. Biomaterials are promising options because they have good biocompatibility and bioactive properties for stimulation of bone regeneration. More interestingly, an integrated material regimen that combines tumour therapy with bone repair is a promising treatment option. Herein, we summarized traditional and biomaterial-mediated maxillofacial tumour treatments and analysed biomaterials for bone defect repair. Furthermore, we proposed a promising and superior design of dual-functional biomaterials for simultaneous tumour therapy and bone regeneration to provide a new strategy for managing maxillofacial tumours and improve the quality of life of patients in the future.