Selenoxide elimination manipulate the oxidative stress to improve the antitumor efficacy

Lipo/TK-CDN/TPP/Y6 nanoparticles inhibit cutaneous melanoma formation

Stimulation of the innate immune stimulator of interferon genes (STING) pathway has been shown to boost anti-tumour immunity. Nevertheless, the systemic delivery of STING agonists to the tumour presents challenges. Therefore, we designed a cyclic dinucleotide (CDN)-based drug delivery system (DDS) combined photothermal therapy (PTT)/photodynamic therapy (PDT)/immunotherapy for cutaneous melanoma. We coencapsulated a reactive oxygen species (ROS)-responsive prodrug thioketone-linked CDN (TK-CDN), and photoresponsive agents chlorin E6 (Y6) within mitochondria-targeting reagent triphenylphosphonium (TPP)-modified liposomes (Lipo/TK-CDN/TPP/Y6). Lipo/TK-CDN/TPP/Y6 exhibited a photothermal effect similar to Y6, along with a superior cellular uptake rate. Upon endocytosis by B16F10 cells, Lipo/TK-CDN/TPP/Y6 generated large amounts of ROS under laser irradiation for PDT. Mice bearing B16F10 tumours were intravenously injected with Lipo/TK-CDN/TPP/Y6 and exposed to irradiation, resulting in a substantial inhibition of tumour growth. Exploration of the mechanism of anti-tumour action showed that Lipo/TK-CDN/TPP/Y6 had a stronger stimulation of STING activation and anti-tumour immune cell infiltration compared to other groups. Hence, the Lipo/TK-CDN/TPP/Y6 nanoparticles offer great potential as a DDS for targeted and on-demand drug release at tumour sites. These nanoparticles exhibit promise as a candidate for precise and controllable combination therapy in the treatment of tumours.

Nano-Engineering Strategies for Tumor-Specific Therapy

Nanodelivery systems (NDSs) provide promising prospects for decreasing drug doses, reducing side effects, and improving therapeutic effects. However, the bioapplications of NDSs are still compromised by their fast clearance, indiscriminate biodistribution, and limited tumor accumulation. Hence, engineering modification of NDSs aiming at promoting tumor-specific therapy and avoiding systemic toxicity is usually needed. An NDS integrating various functionalities, including flexible camouflage, specific biorecognition, and sensitive stimuli-responsiveness, into one sequence would be "smart" and highly effective. Herein, we systematically summarize the related principles, methods, and progress. At the end of the review, we predict the obstacles to precise nanoengineering and prospects for the future application of NDSs.

Selenium-Containing Nanocomplexes Achieve Dual Immune Checkpoint Blockade for NK Cell Reinvigoration

The blockade of immune checkpoints has emerged as a promising strategy for cancer immunotherapy. However, most of the current approaches focus on T cells, leaving natural killer (NK) cell-mediated therapeutic strategies rarely explored. Here, a selenium-containing nanocomplex is developed that acts as a dual immune checkpoint inhibitor to reinvigorate NK cell-based cancer immunotherapy. The Se nanocomplex can deliver and release siRNA that targets programmed death ligand-1 (PD-L1) in tumor cells, thereby silencing the checkpoint receptor PD-L1. The intracellular reactive oxygen species generated by porphyrin derivatives in the nanocomplexes can oxidize the diselenide bond into seleninic acid, which blocks the expression of another checkpoint receptor, human leukocyte antigen E. The blockade of dual immune checkpoints shows synergistic effects on promoting NK cell-mediated antitumoral activity. This study provides a new strategy to reinvigorate NK cell immunity for the development of combined cancer immunotherapy.

Deciphering the Hazardous Effects of AFB1 and T-2 Toxins: Unveiling Toxicity and Oxidative Stress Mechanisms in PK15 Cells and Mouse Kidneys

In China, animal feeds are frequently contaminated with a range of mycotoxins, with Aflatoxin B1 (AFB1) and T-2 toxin (T-2) being two highly toxic mycotoxins. This study investigates the combined nephrotoxicity of AFB1 and T-2 on PK15 cells and murine renal tissues and their related oxidative stress mechanisms. PK15 cells were treated with the respective toxin concentrations for 24 h, and oxidative stress-related indicators were assessed. The results showed that the combination of AFB1 and T-2 led to more severe cellular damage and oxidative stress compared to exposure to the individual toxins (p < 0.05). In the in vivo study, pathological examination revealed that the kidney tissue of mice exposed to the combined toxins showed signs of glomerular atrophy. The contents of oxidative stress-related indicators were significantly increased in the kidney tissue (p < 0.05). These findings suggest that the combined toxins cause significant oxidative damage to mouse kidneys. The study highlights the importance of considering the combined effects of mycotoxins in animal feed, particularly AFB1 and T-2, which can lead to severe nephrotoxicity and oxidative stress in PK15 cells and mouse kidneys. The findings have important implications for animal feed safety and regulatory policy.

Advances in Liposome-Encapsulated Phthalocyanines for Photodynamic Therapy

This updated review aims to describe the current status in the development of liposome-based systems for the targeted delivery of phthalocyanines for photodynamic therapy (PDT). Although a number of other drug delivery systems (DDS) can be found in the literature and have been studied for phthalocyanines or similar photosensitizers (PSs), liposomes are by far the closest to clinical practice. PDT itself finds application not only in the selective destruction of tumour tissues or the treatment of microbial infections, but above all in aesthetic medicine. From the point of view of administration, some PSs can advantageously be delivered through the skin, but for phthalocyanines, systemic administration is more suitable. However, systemic administration places higher demands on advanced DDS, active tissue targeting and reduction of side effects. This review focuses on the already described liposomal DDS for phthalocyanines, but also describes examples of DDS used for structurally related PSs, which can be assumed to be applicable to phthalocyanines as well.

Selenium-Containing Agents Acting on Cancer-A New Hope?

Selenium-containing agents are more and more considered as an innovative potential treatment option for cancer. Light is shed not only on the considerable advancements made in understanding the complex biology and chemistry related to selenium-containing small molecules but also on Se-nanoparticles. Numerous Se-containing agents have been widely investigated in recent years in cancer therapy in relation to tumour development and dissemination, drug delivery, multidrug resistance (MDR) and immune system-related (anti)cancer effects. Despite numerous efforts, Se-agents apart from selenocysteine and selenomethionine have not yet reached clinical trials for cancer therapy. The purpose of this review is to provide a concise critical overview of the current state of the art in the development of highly potent target-specific Se-containing agents.

Biocompatible, bacteria-targeting resveratrol nanoparticles fabricated by Mannich molecular condensation for accelerating infected wound healing

Excessive reactive oxygen species (ROS) and long-term inflammation can delay wound healing and cause tissue damage, while bacterial infection aggravates the wound environment further. It is impossible to resolve all these thorny problems simultaneously with a wound dressing that has only one function. The antioxidative and anti-inflammatory properties of resveratrol (Res) have been proven. However, the effect of Res is non-selective, and high levels of Res can inhibit cell growth and promote oxidation. Res is also difficult to dissolve and possesses insufficient antibacterial properties, so its role is limited. In this study, Res was assembled via Mannich reaction into nanoparticles and functionalized by phenylboric acid, giving rise to targeting bacteria and solving the water-insoluble dilemma of Res. In comparison with Trolox, the assembled Res NPs performed better at scavenging ABTS and DPPH free radicals. Furthermore, Res NPs that targeted bacteria also showed high biocompatibility at concentrations five times higher than pure Res. The activities of Res NPs were comparable to free Res in downregulating the expression of inflammatory cytokines, and reducing intracellular excessive ROS. The gel embedded with Res NPs accelerated the formation of granulation tissue, collagen deposition, and re-epithelialization, facilitating wound healing. The present study suggests that functionalized polyphenol-based materials are preferably suited to the development of tissue engineering biomaterials.

Mechanoresponsive diselenide-crosslinked microgels with programmed ultrasound-triggered degradation and radical scavenging ability for protein protection

In the context of controlled delivery and release, proteins constitute a delicate class of cargo requiring advanced delivery platforms and protection. We here show that mechanoresponsive diselenide-crosslinked microgels undergo controlled ultrasound-triggered degradation in aqueous solution for the release of proteins. Simultaneously, the proteins are protected from chemical and conformational damage by the microgels, which disintegrate to water-soluble polymer chains upon sonication. The degradation process is controlled by the amount of diselenide crosslinks, the temperature, and the sonication amplitude. We demonstrate that the ultrasound-mediated cleavage of diselenide bonds in these microgels facilitates the release and activates latent functionality preventing the oxidation and denaturation of the encapsulated proteins (cytochrome C and myoglobin) opening new application possibilities in the targeted delivery of biomacromolecules.

Mechanoresponsive diselenide-crosslinked microgels undergo controlled ultrasound-triggered degradation and can be used for protein delivery due to their dual protection properties acting as radical scavengers and conformation stabilizers.

Thioanisole ester based logic gate cascade to control ROS-triggered micellar degradation

Thioanisole ester polymer side chains hydrolyze exclusively upon thioether oxidation, showing logic gate response. ROS-induced ester hydrolysis on the hydrophobic domain leads to nanocarrier disassembly with potential for targeted drug release.

Selenium-containing nanoparticles synergistically enhance Pemetrexed&NK cell-based chemoimmunotherapy

NK cell-based immunotherapy and pemetrexed (Pem)-based chemotherapy have broad application prospects in cancer treatment. However, the over-expressed NK cell inhibitory receptor on the surface of cancer cells and the low cell internalization efficiency of Pem greatly limit their clinical application. Herein, we construct a series of selenium-containing nanoparticles to synergistically enhance Pem-based chemotherapy and NK cell-based immunotherapy. The nanoparticles could deliver Pem to tumor sites and strengthen the chemotherapy efficiency of Pem by seleninic acid, which is produced by the oxidation of β-seleno ester. Moreover, seleninic acid can block the expression of inhibitory receptors against NK cells, thereby activating the immunocompetence of NK cells. The in vitro and in vivo experiments reveal the potential chemo-enhancing and immune-activating mechanism of seleninic acid, emphasizing the promising prospects of this strategy in effective chemoimmunotherapy.

Facile Polyphenol-Europium Assembly Enabled Functional Poly(l-Lactic Acid) Nanofiber Mats with Enhanced Antioxidation and Angiogenesis for Accelerated Wound Healing

Burns, trauma, surgery and chronic diabetic ulcers are the most common reasons causing skin wounds in clinic. Thus, developing a functional wound dressing has been an imperative issue. Herein, functional wound dressing (poly(l-lactic acid) PLLA-((tanic acid (TA)/europium (Eu))_n ) is fabricated through a facile polyphenol-europium ion assembly to ameliorate wound microenvironment via scavenging excessive reactive oxygen species (ROS) and promoting angiogenesis. The physicochemical characterization indicates that the multicycle assembled TA/Eu is uniformly deposited on PLLA-(TA/Eu)_n nanofiber mats surface. In vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant tests display good antioxidant ability by scavenging more than 75% ROS, and significantly increasing the antioxidant enzyme levels in vivo. Cytocompatibility experiments illustrate that PLLA-(TA/Eu)_n nanofiber mats can promote the adhesion and proliferation of human umbilical vein endothelial cells (HUVECs) and L929 cells. Meanwhile, real-time quantitative polymerase chain reaction (PCR) (RT-qPCR) and western blot assays illustrate that it can stimulate proangiogenesis by elevating the expression of angiogenesis-related genes and proteins. In vivo Sprague-Dawley (SD) rats experiments indicate that PLLA-(TA/Eu)_n nanofiber mats can significantly promote wound healing by improving both angiogenesis and antioxidant activity. Taken together, the functional PLLA-(TA/Eu)_n nanofiber mats can offer significant promise as wound dressing for accelerated wound healing.

Recent developments in selenium-containing polymeric micelles: prospective stimuli, drug-release behaviors, and intrinsic anticancer activity

Selenium is capable of forming a dynamic covalent bond with itself and other elements and can undergo metathesis and regeneration reactions under optimum conditions. Its dynamic nature endows selenium-containing polymers with striking sensitivity towards some environmental alterations. In the past decade, several selenium-containing polymers were synthesized and used for the preparation of oxidation-, reduction-, and radiation-responsive nanocarriers. Recently, thioredoxin reductase, sonication, and osmotic pressure triggered the cleavage of Se-Se bonds and swelling or disassembly of nanostructures. Moreover, some selenium-containing nanocarriers form oxidation products such as seleninic acids and acrylates with inherent anticancer activities. Thus, selenium-containing polymers hold promise for the fabrication of ultrasensitive and multifunctional nanocarriers of radiotherapeutic, chemotherapeutic, and immunotherapeutic significance. Herein, we discuss the most recent developments in selenium-containing polymeric micelles in light of their architecture, multiple stimuli-responsive properties, emerging immunomodulatory activities, and future perspectives in the delivery and controlled release of anticancer agents.

Bioresponsive nanomedicines based on dynamic covalent bonds

Trends in the development of modern medicine necessitate the efficient delivery of therapeutics to achieve the desired treatment outcomes through precise spatiotemporal accumulation of therapeutics at the disease site. Bioresponsive nanomedicine is a promising platform for this purpose. Dynamic covalent bonds (DCBs) have attracted much attention in studies of the fabrication of bioresponsive nanomedicines with an abundance of combinations of therapeutic modules and carrier function units. DCB-based nanomedicines could be designed to maintain biological friendly synthesis and site-specific release for optimal therapeutic effects, allowing the complex to retain an integrated structure before accumulating at the disease site, but disassembling into individual active components without compromising function in the targeted organs or tissues. In this review, we focus on responsive nanomedicines containing dynamic chemical bonds that can be cleaved by various specific stimuli, enabling achievement of targeted drug release for optimal therapy in various diseases.

Antioxidant stress and anticancer activity of peptide‑chelated selenium in vitro

The association between selenium and peptide in gastric cancer is an important research topic. The present study reported the facile synthesis of anticancer bioactive peptide (ACBP)-functionalized selenium (ACBP-S-Se) particles with enhanced anticancer activities and a detailed mechanistic evaluation of their ability to regulate oxidative stress in vitro. Structural and chemical characterizations were revealed by ultraviolet absorption, Fourier transform infrared, X-ray photoelectron, nuclear magnetic resonance carbon and hydrogen, energy dispersive X-ray spectroscopy and inductively coupled plasma mass spectrometry, as well as scanning electron microscopy. Sulfhydrylation modifications of ACBP were achieved with Sacetylmercaptosuccinic anhydride via chemical absorption. After the polypeptide was modified by sulfhydrylation, the ACBP chain was linked to sulfhydryl groups by amide bonds to form the ACBP-chelated selenium complex. Two gastric cancer cell lines (MKN-45 and MKN-74 cells) demonstrated high susceptibility to ACBP-S-Se particles and displayed significantly decreased proliferation ability following treatment. The results suggested that the bioactive peptide-chelated selenium particles effectively inhibited the proliferation of MKN-45 and MKN-74 cells in vitro. The genes encoding CDK inhibitor 1A (CDKN1A), cyclin B1, thioredoxin (TXN) and mitogen-activated protein kinase kinase kinase 5 are associated with regulation of oxidative stress, while CDKN1A and TXN protect cells by decreasing oxidative stress and promoting cell growth arrest. Therefore, ACBP-S-Se may be an ideal chemotherapeutic candidate for human cancer, especially gastric cancer.

Side-Chain Selenium-Grafted Polymers Combining Antiangiogenesis Treatment with Photodynamic Therapy and Chemotherapy

The abnormal tumor vasculature in solid tumors creates hypoxia and leads to compromising the delivery and anticancer efficiency of nanomedicine. Nanomaterials with intrinsic antiangiogenesis ability might normalize tumor vessels and improve the therapeutic effect of O₂-related treatment like PDT. Herein, we designed and prepared ROS-responsive side-chain selenium-grafted polymers, which had potential antiangiogenic activity, as vehicles to load photodynamic therapeutic agent Ce6 and chemotherapeutic drug oridonin. Under NIR irradiation, the C-Se bonds on the side chain of polymers could be cleaved in the presence of ¹O₂ produced by Ce6 and further formed organic selenic acid through selenoxide elimination reaction. The generated seleninic acid could downregulate the expression of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-2 (MMP-2) to inhibit angiogenesis and further relieve hypoxia. The released oridonin could significantly increase the intracellular ROS concentration. Both could modulate cancer cells' microenvironment to reinforce PDT. Therefore, these nanomedicines could be a good candidate for synergistic treatments of antiangiogenesis treatment, PDT, and chemotherapy.

ROS-responsive liposomes with NIR light-triggered doxorubicin release for combinatorial therapy of breast cancer

BACKGROUND

Reactive oxygen species (ROS)-responsive drug delivery systems (DDSs) are potential tools to minimize the side effects and substantially enhance the therapeutic efficacy of chemotherapy. However, it is challenging to achieve spatially and temporally controllable and accurate drug release in tumor sites based on ROS-responsive DDSs. To solve this problem, we designed a nanosystem combined photodynamic therapy (PDT) and ROS-responsive chemotherapy.

METHODS

Indocyanine green (ICG), an ROS trigger and photosensitizer, and pB-DOX, a ROS-responsive prodrug of doxorubicin (DOX), were coencapsulated in polyethylene glycol modified liposomes (Lipo/pB-DOX/ICG) to construct a combination therapy nanosystem. The safety of nanosystem was assessed on normal HEK-293 cells, and the cellular uptake, intracellular ROS production capacity, target cell toxicity, and combined treatment effect were estimated on human breast cancer cells MDA-MB-231. In vivo biodistribution, biosafety assessment, and combination therapy effects were investigated based on MDA-MB-231 subcutaneous tumor model.

RESULTS

Compared with DOX·HCl, Lipo/pB-DOX/ICG showed higher safety on normal cells. The toxicity of target cells of Lipo/pB-DOX/ICG was much higher than that of DOX·HCl, Lipo/pB-DOX, and Lipo/ICG. After endocytosis by MDA-MB-231 cells, Lipo/pB-DOX/ICG produced a large amount of ROS for PDT by laser irradiation, and pB-DOX was converted to DOX by ROS for chemotherapy. The cell inhibition rate of combination therapy reached up to 93.5 %. After the tail vein injection (DOX equivalent of 3.0 mg/kg, ICG of 3.5 mg/kg) in mice bearing MDA-MB-231 tumors, Lipo/pB-DOX/ICG continuously accumulated at the tumor site and reached the peak at 24 h post injection. Under irradiation at this time point, the tumors in Lipo/pB-DOX/ICG group almost disappeared with 94.9 % tumor growth inhibition, while those in the control groups were only partially inhibited. Negligible cardiotoxicity and no treatment-induced side effects were observed.

CONCLUSIONS

Lipo/pB-DOX/ICG is a novel tool for on-demand drug release at tumor site and also a promising candidate for controllable and accurate combinatorial tumor therapy.

Selenoxide Elimination Triggers Enamine Hydrolysis to Primary and Secondary Amines: A Combined Experimental and Theoretical Investigation

We discuss a novel selenium-based reaction mechanism consisting in a selenoxide elimination-triggered enamine hydrolysis. This one-pot model reaction was studied for a set of substrates. Under oxidative conditions, we observed and characterized the formation of primary and secondary amines as elimination products of such compounds, paving the way for a novel strategy to selectively release bioactive molecules. The underlying mechanism was investigated using NMR, mass spectrometry and density functional theory (DFT).

Advanced Biomedical Applications of Reactive Oxygen Species-Based Nanomaterials in Lung Cancer

Over the years, lung cancer remains the leading cause of cancer deaths in worldwide. In view of this, increasingly importance has been attached to the further optimization and improvement of its treatment. Reactive oxygen species (ROS) play a key role in regulating tumor development and anti-cancer treatment. Recently, the development of nanomaterials provides new platforms for ROS-based cancer treatment methods, which can help to reduce side effects and enhance anti-cancer effects. In recent years, a variety of lung cancer treatment models have been reported, such as chemodynamic therapy (CDT), photodynamic therapy (PDT), radiation therapy (RT) and controlled drug release (CDR). In this review, we are going to discuss the possible mechanism of action and current research status of ROS-based nanomaterials in the treatment of lung cancer in order to provide constructive ideas for relative research and expect this work could inspire the future development of novel lung cancer treatments.

Small changes in the length of diselenide bond-containing linkages exert great influences on the antitumor activity of docetaxel homodimeric prodrug nanoassemblies

Homodimeric prodrug-based self-assembled nanoparticles, with carrier-free structure and ultrahigh drug loading, is drawing more and more attentions. Homodimeric prodrugs are composed of two drug molecules and a pivotal linkage. The influence of the linkages on the self-assembly, in vivo fate and antitumor activity of homodimeric prodrugs is the focus of research. Herein, three docetaxel (DTX) homodimeric prodrugs are developed using different lengths of diselenide bond-containing linkages. Interestingly, compared with the other two linkages, the longest diselenide bond-containing linkage could facilitate the self-delivery of DTX prodrugs, thus improving the stability, circulation time and tumor targeting of prodrug nanoassemblies. Besides, the extension of linkages reduces the redox-triggered drug release and cytotoxicity of prodrug nanoassemblies in tumor cells. Although the longest diselenide bond-containing prodrug nanoassemblies possessed the lowest cytotoxicity to 4T1 cells, their stable nanostructure maintained intact during circulation and achieve the maximum accumulation of DTX in tumor cells, which finally “turned the table”. Our study illustrates the crucial role of linkages in homodimeric prodrugs, and gives valuable proposal for the development of advanced nano-DDS for cancer treatment.

Recent progress of redox-responsive polymeric nanomaterials for controlled release

This perspective focuses on the development of redox-responsive polymeric nanomaterials for controlled payload release within the last four years.

A Drug-Free Therapeutic System for Cancer Therapy by Diselenide-Based Polymers Themselves

The application of nanotechnology-based drug delivery systems has resulted in great progresses in cancer therapy. However, current systems ultimately depend on the action of the drug itself and almost all nanocarriers only serve as excipients without any therapeutic efficacy. Herein, a drug-free therapeutic system is put forward, in which synthetic polymers themselves naturally exhibit effective anticancer activity without the loading of additional chemotherapy drugs. Aiming at this goal, amphiphilic poly(diselenide-carbonate) copolymers (PSeSeTMC), consisting of monomethyl ether poly(ethylene glycol) and diselenide-based polycarbonates, are designed and synthesized to build spherical nanoparticles, which show effective and broad-spectrum anticancer activities against multiple cancer cell lines and high selectivity toward cancer cells. Moreover, the anticancer activities can be well controlled by tuning the selenium contents in polymers. Mechanistic investigations indicate that PSeSeTMC can selectively induce cancer cells to express excessive reactive oxygen species, thereby leading to significant cellular apoptosis. In vivo antitumor studies further demonstrate high therapeutic efficacy and low side effects on normal tissue. Overall, this work provides a novel approach for cancer therapy by utilizing carriers themselves. Considering the fabrication process is pretty simple, this diselenide-based polymeric system has great potential in clinical translation.

Yolk-shell nanovesicles endow glutathione-responsive concurrent drug release and T1 MRI activation for cancer theranostics

The effort of incorporating therapeutic drugs with imaging agents has been one of the mainstreams of nanomedicine, which holds great promise in cancer treatment in terms of monitoring therapeutic drug activity and evaluating prognostic index. However, it is still technically challenging to develop nanomedicine endowing a spatiotemporally controllable mechanism of drug release and activatable imaging capability. Here, we developed a yolk-shell type of GSH-responsive nanovesicles (NVs) in which therapeutic drug (Doxorubicin, DOX) and magnetic resonance imaging (MRI) contrast agent (ultrasmall paramagnetic iron oxide nanoparticles, USPIO NPs) formed complexes (denoted as USD) and were encapsulated inside the NVs. The formation of USD complexes is mediated by both the electrostatic adsorption between DOX and poly(acrylic acid) (PAA) polymers and the DOX-iron coordination effect on USPIO NPs. The obtained USD NVs showed a unique yolk-shell structure with restrained drug activity and quenched T1 MRI contrast ability which, on the other hand, can respond to glutathione (GSH) and lead to drug release and T1 contrast activation in a spatiotemporally concurrent manner. Furthermore, the USD NVs exhibited great potential to kill HCT116 cancer cells in vitro and effectively inhibit the tumor growth in vivo. This study may shed light on the design of sophisticated nanotheranostics in precision nanomedicine.

Carbon dot targeting to nitrogen signaling molecules for inhibiting neuronal death

Ultrasmall carbon dot with targeting ability to nitrogen signaling molecules inhibit neuronal death by regulating the activity of endogenous enzymes.

Organoselenium chemistry-based polymer synthesis

Novel synthesis of selenium containing polymers with pre-determined structures and applications thereof.