Diselenide-crosslinked carboxymethyl chitosan nanoparticles for doxorubicin delivery: Preparation and in vivo evaluation

Visible-Light-Induced Diselenide-Crosslinked Polymeric Micelles for ROS-Triggered Drug Delivery

To synthesize an effective and versatile nano-platform serving as a promising carrier for controlled drug delivery, visible-light-induced diselenide-crosslinked polyurethane micelles were designed and prepared for ROS-triggered on-demand doxorubicin (DOX) release. A rationally designed amphiphilic block copolymer, poly(ethylene glycol)-b-poly(diselenolane diol-co-isophorone diisocyanate)-b-poly(ethylene glycol) (PEG-b-PUSe-b-PEG), which incorporates dangling diselenolane groups within the hydrophobic PU segments, was initially synthesized through the polycondensation reaction. In aqueous media, this type of amphiphilic block copolymer can self-assemble into micellar aggregates and encapsulate DOX within the micellar core, forming DOX-loaded micelles that are subsequently in situ core-crosslinked by diselenides via a visible-light-triggered metathesis reaction of Se-Se bonds. Compared with the non-crosslinked micelles (NCLMs), the as-prepared diselenide-crosslinked micelles (CLMs) exhibited a smaller particle size and improved colloidal stability. In vitro release studies have demonstrated suppressed drug release behavior for CLMs in physiological conditions, as compared to the NCLMs, whereas a burst release of DOX occurred upon exposure to an oxidation environment. Moreover, MTT assay results have revealed that the crosslinked polyurethane micelles displayed no significant cytotoxicity towards HeLa cells. Cellular uptake analyses have suggested the effective internalization of DOX-loaded crosslinked micelles and DOX release within cancer cells. These findings suggest that this kind of ROS-triggered reversibly crosslinked polyurethane micelles hold significant potential as a ROS-responsive drug delivery system.

Design of pH/Redox Co-Triggered Degradable Diselenide-Containing Polyprodrug via a Facile One-Pot Two-Step Approach for Tumor-Specific Chemotherapy

The diselenide bond has attracted intense interest for drug delivery systems (DDSs) for tumor chemotherapy, owing to it possessing higher redox sensitivity than the disulfide one. Various redox-responsive diselenide-containing carriers have been developed for chemotherapeutics delivery. However, the premature drug leakage from these DDSs was significant enough to cause toxic side effects on normal cells. Here, a pH/redox co-triggered degradable polyprodrug was designed as a drug self-delivery system (DSDS) by incorporating drug molecules as structural units in the polymer main chains, using a facile one-pot two-step approach. The proposed PDOX could only degrade and release drugs by breaking both the neighboring acid-labile acylhydrazone and the redox-cleavable diselenide conjugations in the drug's structural units, triggered by the higher acidity and glutathione (GSH) or reactive oxygen species (ROS) levels in the tumor cells. Therefore, a slow solubility-controlled drug release was achieved for tumor-specific chemotherapy, indicating promising potential as a safe and efficient long-acting DSDS for future tumor treatment.

Custom-Design of Multi-Stimuli-Responsive Degradable Silica Nanoparticles for Advanced Cancer-Specific Chemotherapy

Chemotherapy is crucial in oncology for combating malignant tumors but often encounters obatacles such as severe adverse effects, drug resistance, and biocompatibility issues. The advantages of degradable silica nanoparticles in tumor diagnosis and treatment lie in their ability to target drug delivery, minimizing toxicity to normal tissues while enhancing therapeutic efficacy. Moreover, their responsiveness to both endogenous and exogenous stimuli opens up new possibilities for integrating multiple treatment modalities. This review scrutinizes the burgeoning utility of degradable silica nanoparticles in combination with chemotherapy and other treatment modalities. Commencing the elucidation of degradable silica synthesis and degradation mechanisms, emphasis is placed on the responsiveness of these materials to endogenous (e.g., pH, redox reactions, hypoxia, and enzymes) and exogenous stimuli (e.g., light and high-intensity focused ultrasound). Moreover, this exploration delves into strategies harnessing degradable silica nanoparticles in chemotherapy alone, coupled with radiotherapy, photothermal therapy, photodynamic therapy, gas therapy, immunotherapy, starvation therapy, and chemodynamic therapy, elucidating multimodal synergies. Concluding with an assessment of advances, challenges, and constraints in oncology, despite hurdles, future investigations are anticipated to augment the role of degradable silica in cancer therapy. These insights can serve as a compass for devising more efficacious combined tumor treatment strategies.

Stimulus-Responsive Hydrogels for Targeted Cancer Therapy

Cancer is a highly heterogeneous disease and remains a global health challenge affecting millions of human lives worldwide. Despite advancements in conventional treatments like surgery, chemotherapy, and immunotherapy, the rise of multidrug resistance, tumor recurrence, and their severe side effects and the complex nature of the tumor microenvironment (TME) necessitates innovative therapeutic approaches. Recently, stimulus-responsive nanomedicines designed to target TME characteristics (e.g., pH alterations, redox conditions, enzyme secretion) have gained attention for their potential to enhance anticancer efficacy while minimizing the adverse effects of chemotherapeutics/bioactive compounds. Among the various nanocarriers, hydrogels are intriguing due to their high-water content, adjustable mechanical characteristics, and responsiveness to external and internal stimuli, making them promising candidates for cancer therapy. These properties make hydrogels an ideal nanocarrier for controlled drug release within the TME. This review comprehensively surveys the latest advancements in the area of stimulus-responsive hydrogels for cancer therapy, exploring various stimuli-responsive mechanisms, including biological (e.g., pH, redox), chemical (e.g., enzymes, glucose), and physical (e.g., temperature, light), as well as dual- or multi-stimuli responsiveness. Furthermore, this review addresses the current developments and challenges in hydrogels in cancer treatment. Our aim is to provide readers with a comprehensive understanding of stimulus-responsive hydrogels for cancer treatment, offering novel perspectives on their development for cancer therapy and other medical applications.

Recent Progress in Synthetic and Biological Application of Diorganyl Diselenides

Diorganyl diselenides have emerged as privileged structures because they are easy to prepare, have distinct reactivity, and have broad biological activity. They have also been used in the synthesis of natural products as an electrophile in the organoselenylation of aromatic systems and peptides, reductions of alkenes, and nucleophilic substitution. This review summarizes the advancements in methods for the transformations promoted by diorganyl diselenides in the main functions of organic chemistry. Parallel, it will also describe the main findings on pharmacology and toxicology of diorganyl diselenides, emphasizing anti-inflammatory, hypoglycemic, chemotherapeutic, and antimicrobial activities. Therefore, an examination detailing the reactivity and biological characteristics of diorganyl diselenides provides valuable insights for academic researchers and industrial professionals.

Diselenide-Bridged Doxorubicin Dimeric Prodrug: Synthesis and Redox-Triggered Drug Release

The diselenide bond has attracted intense interest in redox-responsive drug delivery systems (DDSs) in tumor chemotherapy, due to its higher sensitivity than the most investigated bond, namely the disulfide bond. Here, a diselenide-bridged doxorubicin dimeric prodrug (D-DOXSeSe) was designed by coupling two doxorubicin molecules with a diselenodiacetic acid (DSeDAA) molecule via α-amidation, as a redox-triggered drug self-delivery system (DSDS) for tumor-specific chemotherapy. The drug release profiles indicated that the D-DOXSeSe could be cleaved to release the derivatives selenol (DOX-SeH) and seleninic acid (DOX-SeOOH) with the triggering of high GSH and H2O2, respectively, indicating the double-edged sword effect of the lower electronegativity of the selenide atom. The resultant solubility-controlled slow drug release performance makes it a promising candidate as a long-acting DSDS in future tumor chemotherapy. Moreover, the interaction between the conjugations in the design of self-immolation traceless linkers was also proposed for the first time as another key factor for a desired precise tumor-specific chemotherapy, besides the conjugations themselves.

Redox-Responsive Polymeric Nanoparticle for Nucleic Acid Delivery and Cancer Therapy: Progress, Opportunities, and Challenges

Cancer development and progression of cancer are closely associated with the activation of oncogenes and loss of tumor suppressor genes. Nucleic acid drugs (e.g., siRNA, mRNA, and DNA) are widely used for cancer therapy due to their specific ability to regulate the expression of any cancer-associated genes. However, nucleic acid drugs are negatively charged biomacromolecules that are susceptible to serum nucleases and cannot cross cell membrane. Therefore, specific delivery tools are required to facilitate the intracellular delivery of nucleic acid drugs. In the past few decades, a variety of nanoparticles (NPs) are designed and developed for nucleic acid delivery and cancer therapy. In particular, the polymeric NPs in response to the abnormal redox status in cancer cells have garnered much more attention as their potential in redox-triggered nanostructure dissociation and rapid intracellular release of nucleic acid drugs. In this review, the important genes or signaling pathways regulating the abnormal redox status in cancer cells are briefly introduced and the recent development of redox-responsive NPs for nucleic acid delivery and cancer therapy is systemically summarized. The future development of NPs-mediated nucleic acid delivery and their challenges in clinical translation are also discussed.

Fabrication of targeted and pH responsive lysozyme-hyaluronan nanoparticles for 5-fluorouracil and curcumin co-delivery in colorectal cancer therapy

Green nanotechnology is considered a promising method to construct functional materials with significant anticancer activity, while overcoming the shortcomings of traditional synthesis process complexity and high organic solvents consumption. Thus, in this study, we report for the first time the rational design and green synthesis of functionalized 5-fluorouracil and curcumin co-loaded lysozyme-hyaluronan composite colloidal nanoparticles (5-Fu/Cur@LHNPs) for better targeted colorectal cancer therapy with minimized side effects. The functionalized 5-Fu/Cur@LHNPs exhibit stabilized particle size (126.1 nm) with excellent homogeneity (PDI = 0.1), favorable colloidal stabilities, and excellent re-dispersibility. In vitro cell experiments illustrate that the cellular uptake of 5-Fu/Cur@LHNPs was significantly improved and further promoted a higher apoptosis ratio of HCT-116 cells. Compared with the control group, the 5-Fu/Cur@LHNPs formulation group achieved effective inhibition (60.1 %) of colorectal tumor growth. The alcohol-free self-assembly method to construct 5-Fu/Cur@LHNPs is simple and safe for a translational chemotherapy drug, also to promote more robust delivery systems for treating colorectal cancer.

Optimized DOX Drug Deliveries via Chitosan-Mediated Nanoparticles and Stimuli Responses in Cancer Chemotherapy: A Review

Chitosan nanoparticles (NPs) serve as useful multidrug delivery carriers in cancer chemotherapy. Chitosan has considerable potential in drug delivery systems (DDSs) for targeting tumor cells. Doxorubicin (DOX) has limited application due to its resistance and lack of specificity. Chitosan NPs have been used for DOX delivery because of their biocompatibility, biodegradability, drug encapsulation efficiency, and target specificity. In this review, various types of chitosan derivatives are discussed in DDSs to enhance the effectiveness of cancer treatments. Modified chitosan-DOX NP drug deliveries with other compounds also increase the penetration and efficiency of DOX against tumor cells. We also highlight the endogenous stimuli (pH, redox, enzyme) and exogenous stimuli (light, magnetic, ultrasound), and their positive effect on DOX drug delivery via chitosan NPs. Our study sheds light on the importance of chitosan NPs for DOX drug delivery in cancer treatment and may inspire the development of more effective approaches for cancer chemotherapy.

Formulation of DOX-dimer with bi-functionalized chitooligosaccharide for tumor-specific self-boosted drug release and synergistic chemo/chemodynamic therapy

The toxic side effects and possible drug resistance of the chemotherapeutics hinder their antitumor efficacy. Here, a pH/reactive oxygen species (ROS) dual-triggered nanodrug was developed for the tumor-specific self-boosted drug release and synergistic chemo/chemodynamic therapy, by formulating ROS-cleavable doxorubicin (DOX)-based dimer (DOX-TK-DOX) with bi-functionalized chitooligosaccharide (COS-Fc-TK) with ferrocenecarboxylic acid (Fc) and thioketal (TK). The resultant DOX-TK-DOX/COS-Fc-TK nanoparticles with a high DOX content of 39.70 % showed tumor-specific self-boosted drug release, which was triggered by highly toxic OH generated via Fc-catalyzed Fenton reaction of the endogenous H2O2 in tumor intracellular microenvironment. As a result, a synergistic chemo/chemodynamic therapy with combination index (CI) of 0.94 was achieved for selective treatment of tumors.

Polysaccharide-based tumor microenvironment-responsive drug delivery systems for cancer therapy

The biochemical indicators of tumor microenvironment (TME) that are different from normal tissues provide the possibility for constructing intelligent drug delivery systems (DDSs). Polysaccharides with good biocompatibility, biodegradability, and unique biological properties are ideal materials for constructing DDSs. Nanogels, micelles, organic-inorganic nanocomposites, hydrogels, and microneedles (MNs) are common polysaccharide-based DDSs. Polysaccharide-based DDSs enable precise control of drug delivery and release processes by incorporating TME-specific biochemical indicators. The classification and design strategies of polysaccharide-based TME-responsive DDSs are comprehensively reviewed. The advantages and challenges of current polysaccharide-based DDSs are summarized and the future directions of development are foreseen. The polysaccharide-based TME-responsive DDSs are expected to provide new strategies and solutions for cancer therapy and make important contributions to the realization of precision medicine.

Recent theranostic applications of hydrogen peroxide-responsive nanomaterials for multiple diseases

It is well established that hydrogen peroxide (H2O2) is associated with the initiation and progression of many diseases. With the rapid development of nanotechnology, the diagnosis and treatment of those diseases could be realized through a variety of H2O2-responsive nanomaterials. In order to broaden the application prospects of H2O2-responsive nanomaterials and promote their development, understanding and summarizing the design and application fields of such materials has attracted much attention. This review provides a comprehensive summary of the types of H2O2-responsive nanomaterials including organic, inorganic and organic-inorganic hybrids in recent years, and focused on their specific design and applications. Based on the type of disease, such as tumors, bacteria, dental diseases, inflammation, cardiovascular diseases, bone injury and so on, key examples for above disease imaging diagnosis and therapy strategies are introduced. In addition, current challenges and the outlook of H2O2-responsive nanomaterials are also discussed. This review aims to stimulate the potential of H2O2-responsive nanomaterials and provide new application ideas for various functional nanomaterials related to H2O2.

Arginase from Priestia megaterium and the Effects of CMCS Conjugation on Its Enzymological Properties

Arginase has shown promising potential in treating cancers by arginine deprivation therapy; however, low enzymatic activity and stability of arginase are impeding its development. This study was aimed to improve the enzymological properties of a marine bacterial arginase by carboxymethyl chitosan (CMCS) conjugation. An arginase producing marine bacterium Priestia megaterium strain P6 was isolated and identified. The novel arginase PMA from the strain was heterologously expressed, purified, and then conjugated to CMCS by ionic gelation with calcium chloride as the crosslinking agent. Enzymological properties of both PMA and CMCS-PMA conjugate were determined. The optimum temperature for PMA and CMCS-PMA at pH 7 were 60 °C and 55 °C, respectively. The optimum pH for PMA and CMCS-PMA at 37 °C were pH 10 and 9, respectively. CMCS-PMA showed higher thermostability than PMA over 55-70 °C and higher pH stability over pH 4-11 with the highest pH stability at pH 7. At 37 °C and pH of 7, i.e., around the human blood temperature and pH, CMCS-PMA was higher than the free PMA in enzymatic activity and stability by 24% and 21%, respectively. CMCS conjugation not only changed the optimum temperature, optimum pH, and enzymatic activity of PMA, but also improved its pH stability and temperature stability, and thus made it more favorable for medical application.

GE11-modified carboxymethyl chitosan micelles to deliver DOX·PD-L1 siRNA complex for combination of ICD and immune escape inhibition against tumor

Programmed cell death-ligand 1 (PD-L1) small interfering RNA (siRNA) achieves tumor immunotherapy by restoring the immune response of T cells, but the efficacy of PD-1/PD-L1 monotherapy is relatively low. While immunogenic cell death (ICD) can improve the response of most tumors to anti-PD-L1 and enhance tumor immunotherapy. Herein, a targeting peptide GE11-functionalized dual-responsive carboxymethyl chitosan (CMCS) micelle (G-CMssOA) is developed for simultaneous delivery of PD-L1 siRNA and doxorubicin (DOX) in a complex form of DOX·PD-L1 siRNA (D&P). The complex-loaded micelles (G-CMssOA/D&P) have good physiological stability and pH/reduction responsiveness, and improve the intratumoral infiltration of CD4⁺ and CD8⁺ T cells, reduce Tregs (TGF-β), and increase the secretion of immune-stimulatory cytokine (TNF-α). The combination of DOX-induced ICD and PD-L1 siRNA-mediated immune escape inhibition significantly improves anti-tumor immune response and inhibits tumor growth. This complex delivery strategy provides a new approach for effectively delivering siRNA and enhancing anti-tumor immunotherapy.

Eco-friendly chitosan-based nanostructures in diabetes mellitus therapy: Promising bioplatforms with versatile therapeutic perspectives

Nature-derived polymers, or biopolymers, are among the most employed materials for the development of nanocarriers. Chitosan (CS) is derived from the acetylation of chitin, and this biopolymer displays features such as biocompatibility, biodegradability, low toxicity, and ease of modification. CS-based nano-scale delivery systems have been demonstrated to be promising carriers for drug and gene delivery, and they can provide site-specific delivery of cargo. Owing to the high biocompatibility of CS-based nanocarriers, they can be used in the future in clinical trials. On the other hand, diabetes mellitus (DM) is a chronic disease that can develop due to a lack of insulin secretion or insulin sensitivity. Recently, CS-based nanocarriers have been extensively applied for DM therapy. Oral delivery of insulin is the most common use of CS nanoparticles in DM therapy, and they improve the pharmacological bioavailability of insulin. Moreover, CS-based nanostructures with mucoadhesive features can improve oral bioavailability of insulin. CS-based hydrogels have been developed for the sustained release of drugs and the treatment of DM complications such as wound healing. Furthermore, CS-based nanoparticles can mediate delivery of phytochemicals and other therapeutic agents in DM therapy, and they are promising compounds for the treatment of DM complications, including nephropathy, neuropathy, and cardiovascular diseases, among others. The surface modification of nanostructures with CS can improve their properties in terms of drug delivery and release, biocompatibility, and others, causing high attention to these nanocarriers in DM therapy.

Bioengineered nanogenerator with sustainable reactive oxygen species storm for self-reinforcing sono-chemodynamic oncotherapy

Oxidative stress-based antitumor modalities derived from reactive oxygen species (ROS) storms have attracted increasing attention. Nevertheless, low delivery efficiency, poor selectivity, hypoxia and overexpressed glutathione (GSH) have severely restricted the sustainable generation of the ROS storm in tumor cells. Herein, we design a bioengineered nanogenerator by coordination-driven co-assembly of sonosensitizer indocyanine green (ICG), Fenton-like agent copper ion (Cu^Ⅱ) and mitochondrial respiratory inhibitor metformin (MET), which is then camouflaged by a cancer cytomembrane to induce a sustainable intracellular ROS storm for on-demand self-reinforcing sono-chemodynamic oncotherapy. Such a nanogenerator with a core-shell structure, suitable diameter and outstanding stability can efficiently accumulate in tumor regions and then internalize into tumor cells through the camouflaging and homologous targeting strategy of the cancer cytomembrane. The nanogenerator shows an exceptional instability under the triple stimulations of acidic lysosomes, overexpressed GSH and ultrasound (US) radiation, thereby resulting in the rapid disassembly and burst drug release. Interestingly, the released MET significantly enhances the sonodynamic therapy (SDT) efficacy of the released ICG by inhibiting mitochondrial respiration and meanwhile the released Cu^Ⅱ obviously reduces ROS elimination by downregulating overexpressed GSH for self-amplifying and self-protecting the intracellular ROS storm. Moreover, such a nanogenerator almost completely achieves the tumor ablation in vivo in a single therapy cycle. Taken together, our bioengineered nanogenerator with a sustainable ROS storm can provide a promising strategy for ROS storm-based oncotherapy.

Biomaterials Based on Chitosan and Its Derivatives and Their Potential in Tissue Engineering and Other Biomedical Applications-A Review

In the times of dynamically developing regenerative medicine, more and more attention is focused on the use of natural polymers. This is due to their high biocompatibility and biodegradability without the production of toxic compounds, which means that they do not hurt humans and the natural environment. Chitosan and its derivatives are polymers made most often from the shells of crustaceans and are biodegradable and biocompatible. Some of them have antibacterial or metal-chelating properties. This review article presents the development of biomaterials based on chitosan and its derivatives used in regenerative medicine, such as a dressing or graft of soft tissues or bones. Various examples of preparations based on chitosan and its derivatives in the form of gels, films, and 3D structures and crosslinking products with another polymer are discussed herein. This article summarizes the latest advances in medicine with the use of biomaterials based on chitosan and its derivatives and provides perspectives on future research activities.

Characterization of a novel marine microbial uricase from Priestia flexa and evaluation of the effects of CMCS conjugation on its enzymatic properties

A novel uricase producing marine bacterium Priestia flexa alkaAU was isolated and identified. The 16S rDNA and the uricase coding gene were sequenced, analyzed and submitted to GenBank. The uricase from Priestia flexa alkaAU (PFU) was purified, determined to be 58.87 kDa, and conjugated with carboxymethyl chitosan (CMCS) by ionic gelation. CMCS conjugation had no effect on the optimum pH of PFU but decreased the optimum temperature by 10 °C. CMCS conjugation increased the specific activity of PFU by 53% at the human body temperature (37 °C) and small intestine's pH (pH 6.8). Uricase thermostabilizing ability of CMCS was significant in the range of 37-80 °C but not at lower temperatures. For improvement of the pH stability of PFU, CMCS was more effective at pHs 3-5 than pHs 6-11. CMCS increased the half-life of PFU against artificial intestinal fluid by 1.5 folds, which demonstrated the potential capability of CMCS-PFU for oral administration.

A glutathione-sensitive drug delivery system based on carboxymethyl chitosan co-deliver Rose Bengal and oxymatrine for combined cancer treatment

At present, monotherapy of tumor has not met the clinical needs, due to high doses, poor efficacy, and the emergence of drug resistance. Combination therapy can effectively solve these problems, which is a better option for tumor suppression. Based on this, we developed a novel glutathione-sensitive drug delivery nanoparticle system (OMT/CMCS-CYS-RB NPs) for oral cancer treatment. Briefly, carboxymethyl chitosan (CMCS) was used as a carrier to simultaneously load Rose Bengal (RB) and oxymatrine (OMT). The OMT/CMCS-CYS-RB NPs prepared by ion crosslinking were spheres with a stable structure. In addition, the nanoparticles can be excited in vitro to generate a large amount of singlet oxygen, which has a good photodynamic effect. In vitro anti-tumor activity study showed that the nanoparticles after the laser enhanced therapeutic efficacy on tumor cells compared with the free drug and exhibited well security. Furthermore, OMT/CMCS-CYS-RB NPs could inhibit the PI3K/AKT signaling pathway in oxidative stress, and realize tumor apoptosis through mitochondria-related pathways. In conclusion, this combination delivery system for delivering RB and OMT is a safe and effective strategy, which may provide a new avenue for the tumor treatment.

Redox-Responsive Drug Delivery Systems: A Chemical Perspective

With the widespread global impact of cancer on humans and the extensive side effects associated with current cancer treatments, a novel, effective, and safe treatment is needed. Redox-responsive drug delivery systems (DDSs) have emerged as a potential cancer treatment with minimal side effects and enhanced site-specific targeted delivery. This paper explores the physiological and biochemical nature of tumors that allow for redox-responsive drug delivery systems and reviews recent advances in the chemical composition and design of such systems. The five main redox-responsive chemical entities that are the focus of this paper are disulfide bonds, diselenide bonds, succinimide-thioether linkages, tetrasulfide bonds, and platin conjugates. Moreover, as disulfide bonds are the most commonly used entities, the review explored disulfide-containing liposomes, polymeric micelles, and nanogels. While various systems have been devised, further research is needed to advance redox-responsive drug delivery systems for cancer treatment clinical applications.