Advancements in microneedle technology: current status and next-generation innovations

Microneedle technology is a pivotal component of third-generation transdermal drug delivery systems featuring tiny needles that create temporary microscopic channels in the stratum corneum which facilitate drug penetration in the dermis. This review offers a detailed examination of the current types of microneedles, including solid, coated, dissolving, hollow, and swelling microneedles, along with their preparation techniques as well as their benefits and challenges. Use of 3D printing technology is especially gaining significant attention due to its ability to achieve the high dimensional accuracy required for precise fabrication. Additionally, its customisability presents significant potential for exploring new designs and creating personalised microneedles products. Furthermore, this review explores next generation microneedles, especially stimuli-responsive microneedle, bioinspired microneedle and microneedles combined with other transdermal technology like sonophoresis, electroporation and iontophoresis. Regulatory aspects, characterisation techniques, safety considerations, and cost factors have also been addressed which are crucial for translation from lab to the market.

Thermally Responsive Selenide-containing Materials Based on Transalkylation of Selenonium Salts

Covalent adaptable networks (CANs) possess unique properties as a result of their internal dynamic bonds, such as self-healing and reprocessing abilities. In this study, we report a thermally responsive C-Se dynamic covalent chemistry (DCC) that relies on the transalkylation exchange between selenonium salts and selenides, which undergo a fast transalkylation reaction in the absence of any catalyst. Additionally, we demonstrate the presence of a dissociative mechanism in the absence of selenide groups. After incorporation of this DCC into selenide-containing polymer materials, it was observed that the cross-linked networks display varying dynamic exchange rates when using different alkylation reagents, suggesting that the reprocessing capacity of selenide-containing materials can be regulated. Also, by incorporating selenonium salts into polymer materials, we observed that the materials exhibited good healing ability at elevated temperatures as well as excellent solvent resistance at ambient temperature. This novel dynamic covalent chemistry thus provides a straightforward method for the healing and reprocessing of selenide-containing materials.

Stimuli-responsive nanocarrier delivery systems for Pt-based antitumor complexes: a review

Platinum-based anticancer drugs play a crucial role in the clinical treatment of various cancers. However, the application of platinum-based drugs is heavily restricted by their severe toxicity and drug resistance/cross resistance. Various drug delivery systems have been developed to overcome these limitations of platinum-based chemotherapy. Stimuli-responsive nanocarrier drug delivery systems as one of the most promising strategies attract more attention. And huge progress in stimuli-responsive nanocarrier delivery systems of platinum-based drugs has been made. In these systems, a variety of triggers including endogenous and extracorporeal stimuli have been employed. Endogenous stimuli mainly include pH-, thermo-, enzyme- and redox-responsive nanocarriers. Extracorporeal stimuli include light-, magnetic field- and ultrasound responsive nanocarriers. In this review, we present the recent advances in stimuli-responsive drug delivery systems with different nanocarriers for improving the efficacy and reducing the side effects of platinum-based anticancer drugs.

Selenium-decorated biocompatible honeycomb films with redox-switchable surface for controlling cell adhesion/detachment

HYPOTHESIS

Selenium (Se)-containing compound is sensitive to redox stimulation, showing hydrophobic-hydrophilic reversible transition. Introduction of such compound into honeycomb film could confer on it redox-switchable surface wettability, which is expected to control cell adhesion/detachment behavior.

EXPERIMENTS

Didodecyl selenide was designed and mixed with polystyrene to prepare honeycomb films using "breath figure" method. The film microstructures were characterized by scanning electron microscope and atomic force microscopy, and the arrangement of Se atoms in honeycomb film was determined by X-ray photoelectron spectroscopy and energy dispersive spectrometry. The variation of film wettability upon the alternating stimulation of H₂O₂ and Vc was examined. Then the cell adhesion, proliferation, and controlled detachment on honeycomb films were conducted.

FINDINGS

The introduction of didodecyl selenide helps to form ordered honeycomb film, and Se atoms were found to located on the bottom, pore walls, and top surface of the film. The presence of didodecyl selenide not only greatly improves film biocompatibility by enhancing cell thioredoxin reductase activity, but also imparts the film with H₂O₂-/vitamin C-regulated tunable wettability that controls cell adhesion and detachment. H₂O₂ treatment produces a hydrophilic surface for cell adhesion and proliferation, whereas the addition of vitamin C generates hydrophobic surfaces and allows cells to detach while remaining alive with high activity.

Diselenide–yne chemistry for selenium-containing linear polymer modification

Selenium-containing brush polymers with diverse functional segments were easily prepared through diselenide–yne chemistry.

Emerging strategies based on nanomaterials for ionizing radiation-optimized drug treatment of cancer

Drug-radiotherapy is a common and effective combinational treatment for cancer. This study aimed to explore the ionizing radiation-optimized drug treatment based on nanomaterials so as to improve the synergistic efficacy of drug-radiotherapy against cancer and limit the adverse effect on healthy organs. In this review, these emerging strategies were divided into four parts. First, the delivery of the drug-loaded nanoparticles was optimized owing to the strengthened passive targeting process, active targeting process, and cell targeting process of nanoparticles after ionizing radiation exposure. Second, nanomaterials were designed to respond to the ionizing radiation, thus leading to the release of the loading drugs controllably. Third, radiation-activated pro-drugs were loaded onto nanoparticles for radiation-triggered drug therapy. In particular, nontoxic nanoparticles with radiosensitization capability and innocuous radio-dynamic contrast agents can be considered as radiation-activated drugs, which were discussed in this review. Fourth, according to the various synergetic mechanisms, radiotherapy could improve the drug response of cancer, obtaining optimized drug-radiotherapy. Finally, relative suggestions were provided to further optimize these aforementioned strategies. Therefore, a novel topic was selected and the emerging strategies in this region were discussed, aiming to stimulate the inspiration for the development of ionizing radiation-optimized drug treatment based on nanomaterials.

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.

Coordination and Redox Dual-Responsive Mesoporous Organosilica Nanoparticles Amplify Immunogenic Cell Death for Cancer Chemoimmunotherapy

Amplifying the chemotherapy-driven immunogenic cell death (ICD) for efficient and safe cancer chemoimmunotherapy remains a challenge. Here, a potential ICD nanoamplifier containing diselenide-bridged mesoporous organosilica nanoparticles (MONs) and chemotherapeutic ruthenium compound (KP1339) to achieve cancer chemoimmunotherapy is tailored. KP1339-loaded MONs show controlled drug release profiles via glutathione (GSH)-responsive competitive coordination and matrix degradation. High concentration of MONs selectively evoked reactive oxygen species production, GSH depletion, and endoplasmic reticulum stress in cancer cells, thus amplifying the ICD of KP1339 and boosting robust antitumor immunological responses. After the combination of PD-L1 checkpoint blockade, cancer cell membrane-cloaked KP1339-loaded MONs not only regress primary tumor growth with low systemic toxicity, but also inhibit distant tumor growth and pulmonary metastasis of breast cancer. The results have shown the potential of coordination and redox dual-responsive MONs boosting amplified ICD for cancer chemoimmunotherapy.

Stimuli-responsive transdermal microneedle patches

Microneedle (MN) patches consisting of miniature needles have emerged as a promising tool to perforate the stratum corneum and translocate biomolecules into the dermis in a minimally invasive manner. Stimuli-responsive MN patches represent emerging drug delivery systems that release cargos on-demand as a response to internal or external triggers. In this review, a variety of stimuli-responsive MN patches for controlled drug release are introduced, covering the mechanisms of action toward different indications. Future opportunities and challenges with respect to clinical translation are also discussed.

Visible-to-NIR-Light Activated Release: From Small Molecules to Nanomaterials

Photoactivatable (alternatively, photoremovable, photoreleasable, or photocleavable) protecting groups (PPGs), also known as caged or photocaged compounds, are used to enable non-invasive spatiotemporal photochemical control over the release of species of interest. Recent years have seen the development of PPGs activatable by biologically and chemically benign visible and near-infrared (NIR) light. These long-wavelength-absorbing moieties expand the applicability of this powerful method and its accessibility to non-specialist users. This review comprehensively covers organic and transition metal-containing photoactivatable compounds (complexes) that absorb in the visible- and NIR-range to release various leaving groups and gasotransmitters (carbon monoxide, nitric oxide, and hydrogen sulfide). The text also covers visible- and NIR-light-induced photosensitized release using molecular sensitizers, quantum dots, and upconversion and second-harmonic nanoparticles, as well as release via photodynamic (photooxygenation by singlet oxygen) and photothermal effects. Release from photoactivatable polymers, micelles, vesicles, and photoswitches, along with the related emerging field of photopharmacology, is discussed at the end of the review.

Methionine-Based pH and Oxidation Dual-Responsive Block Copolymer: Synthesis and Fabrication of Protein Nanogels

In this paper, we synthesized a block copolymer containing pendent thioether functionalities by reversible addition-fragmentation chain transfer polymerization of a tert-butyloxycarbonyl (Boc)-l-methionine-(2-methacryloylethyl)ester (Boc-METMA) monomer using a poly(ethylene glycol) (PEG)-based chain transfer agent. The deprotection of Boc groups resulted in an oxidation and pH dual-responsive cationic block copolymer PEG-b-P(METMA). The block copolymer PEG-b-P(METMA) possessing protonable amine groups was water-soluble at pH < 6.0 and self-assembled to form spherical micelles at pH > 6.0. In the presence of H₂O₂, the micelles first became highly swollen with time and completely disassembled at last, demonstrating the H₂O₂-responsive feature because of the oxidation of hydrophobic thioether to hydrophilic sulfoxide. The anticancer drug curcumin (Cur) was entrapped in the polymeric micelles and the Cur-loaded micelles displayed a H₂O₂-triggered release profile as well as a pH-dependent release behavior, making PEG-b-P(METMA) micelles promising nanocarriers for reactive oxygen species-responsive drug delivery. Taking advantage of the protonated amine groups, the cationic polyelectrolyte PEG-b-P(METMA) formed polyion complex micelles with glucose oxidase (GOx) through electrostatic interactions at pH 5.8. By cross-linking the cores of PIC micelles with glutaraldehyde, the PIC micelles were fixed to generate stable GOx nanogels under physiological conditions. The GOx nanogels were glucose-responsive and exhibited glucose-dependent H₂O₂-generation activity in vitro and improved storage and thermal stability of GOx. Cur can be encapsulated in the GOx nanogels, and the Cur-loaded GOx nanogels demonstrate the glucose-responsive release profile. The GOx nanogels displayed high cytotoxicity to 4T1 cells and were effectively internalized by the cells. Therefore, these GOx nanogels have potential applications in the areas of cancer starvation and oxidation therapy.

Self-Assembled Supramolecular Micelles with pH-Responsive Properties for More Effective Cancer Chemotherapy

pH-Responsive hydrogen-bonded supramolecular micelles, composed of a water-soluble poly(ethylene glycol) polymer with two terminal sextuple hydrogen bonding groups, can spontaneously organize in aqueous media to give well-defined, uniformly sized spherical micelles. The supramolecular micelles exhibit a number of unique physical characteristics, such as interesting amphiphilic behavior, desirable micellar size and nanospherical morphology, excellent biocompatibility, tailorable drug-loading capacities, and high structural stability in media containing serum or red blood cells. In addition, the drug release kinetics of drug-loaded micelles can be easily manipulated to achieve the desired release profile by regulating the environmental pH, thus these micelles are highly attractive candidates as an intelligent drug carrier system for cancer therapy. Cytotoxicity assays showed that the drug-loaded micelles induced pH-dependent intracellular drug release and exerted strong antiproliferative and cytotoxic activities toward cancer cells. Importantly, cellular uptake and flow cytometric analyses confirmed that a mildly acidic intracellular environment significantly increased cellular internalization of the drug-loaded micelles and subsequent drug release in the cytoplasm and nucleus of cancer cells, resulting in more effective induction of apoptotic cell death. Thus, this system may provide an efficient route toward achieving the fundamental properties and practical realization of pH-sensitive drug-delivery systems for chemotherapy.

Organoselenium chemistry-based polymer synthesis

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

Redox-Responsive Fluorescent Polycarbonates Based on Selenide for Chemotherapy of Triple-Negative Breast Cancer

Transient increase of reactive oxygen species (ROS) is vital for some physiological processes, whereas the chronic and sustained high ROS level is usually implicated in the inflammatory diseases and cancers. Herein, we report the innovative redox-responsive theranostic micellar nanoparticles that are able to load anticancer drugs through coordination and hydrophobic interaction and to fluorescently monitor the intracellular redox status. The nanoparticles were formed by the amphiphilic block copolymers composed of a PEG segment and a selenide-containing hydrophobic polycarbonate block with a small fraction of coumarin-based chromophore. Under the alternative redox stimulation that might be encountered in the physiological process of some healthy cells, these nanoparticles underwent the reversible changes in size, morphology, and fluorescence intensity. With the assistance of small model compounds, we clarified the chemistry behind these changes, that is, the redox triggered reversible transformation between selenide and selenoxide. Upon the monotonic oxidation similar to the sustained high ROS level of cancer cells, the nanoparticles could be disrupted completely, which was accompanied by the drastic decrease in fluorescence. Cisplatin and paclitaxel were simultaneously coloaded in the nanoparticles with a moderate efficacy, and the coordination between selenide and platinum improved the stability of the drug-loaded nanoparticles against dilution. The naked nanoparticles are cytocompatible, whereas the dual drug-loaded nanoparticles exhibited a concentration dependent and synergistic cytotoxicity to triple-negative breast cancer (TNBC) cells. Of importance, the drug-loaded nanoparticles are much more toxic to TNBC cells than to normal cells due in part to ROS overproduction in the former cell lines.

Recent Advances on Reactive Oxygen Species-Responsive Delivery and Diagnosis System

Reactive oxygen species (ROS) play crucial roles in biological metabolism and intercellular signaling. However, ROS level is dramatically elevated due to abnormal metabolism during multiple pathologies, including neurodegenerative diseases, diabetes, cancer, and premature aging. By taking advantage of the discrepancy of ROS levels between normal and diseased tissues, a variety of ROS-sensitive moieties or linkers have been developed to design ROS-responsive systems for the site-specific delivery of drugs and genes. In this review, we summarized the ROS-responsive chemical structures, mechanisms, and delivery systems, focusing on their current advances for precise drug/gene delivery. In particular, ROS-responsive nanocarriers, prodrugs, and supramolecular hydrogels are summarized in terms of their application for drug/gene delivery, and common strategies to elevate or diminish cellular ROS concentrations, as well as the recent development of ROS-related imaging probes were also discussed.

One-pot cascade polymerization based on the addition reactions of electrophilic selenium reagents to alkenes

A direct polymerization based on the addition reactions of electrophilic selenium reagents to alkenes was established.

Enzymatic synthesis of selenium-containing amphiphilic aliphatic polycarbonate as an oxidation-responsive drug delivery vehicle

Although functional aliphatic polycarbonates (APCs) have attracted prominent research interest as stimuli-responsive biomaterials, the majority of functional APCs are fabricated by detrimental organometallic catalysts or organo-catalysts. Herein, a facile synthetic strategy based on enzymatic polymerization was developed to construct a selenium-containing amphiphilic aliphatic polycarbonate (mPEG-b-CMP₄₅). Specifically, the selenium in its backbone framework underwent a hydrophobic–hydrophilic transition upon exposure to the abnormal ROS level of the tumor, thus providing a promising platform for ROS-triggered drug release. This amphiphilic mPEG-b-CMP₄₅ efficiently encapsulated doxorubicin (DOX) via self-assembly in aqueous solution and showed an excellent ability to regulate the release of DOX in response to H₂O₂ at biologically relevant concentrations (100 μM). These DOX-loaded nanoparticles could easily be internalized into U87 cells and possess the inherent antitumor properties of DOX, while they exhibited much lower cytotoxicity in normal cells HL-7702. Moreover, in many cases, the introduction of selenium caused high cytotoxicity of the materials, but the cytotoxicity results in HL-7702 cells demonstrated the good biocompatibility of mPEG-b-CMP₄₅. These collective data suggested the potential use of mPEG-b-CMP₄₅ as a biocompatible and smart drug delivery vehicle.

A facile synthetic strategy based on enzymatic polymerization was developed to construct a ROS-responsive polycarbonate served as biocompatible drug vehicle.

Reversibly core-crosslinked PEG-P(HPMA) micelles: Platinum coordination chemistry for competitive-ligand-regulated drug delivery

HYPOTHESIS

The presence of pendant thioether groups on poly(ethylene glycol)-poly(N(2-hydroxypropyl) methacrylamide) (PEG-P(HPMA)) block copolymers allows for platinum-mediated coordinative micellar core-crosslinking, resulting in enhanced micellar stability and stimulus-responsive drug delivery.

EXPERIMENTS

A new PEG-P(HPMA) based block copolymer with pendant 4-(methylthio)benzoyl (MTB) groups along the P(HPMA) block was synthesized by free radical polymerization of a novel HPMA-MTB monomer using a PEG based macro-initiator. As crosslinker the metal-organic linker [ethylenediamineplatinum(II)]²⁺ was used, herein called Lx, which is a coordinative linker molecule that has been used for the conjugation of drug molecules to a number of synthetic or natural carrier systems such as hyperbranched polymers and antibodies.

FINDINGS

The introduction of Lx in the micellar core results in a smaller size, a lower critical micelle concentration and a better retention of the hydrophobic drug curcumin thanks to coordination bonds between the central platinum atom of Lx and thioether groups on different polymer chains. The drug release from Lx crosslinked micelles is significantly accelerated under conditions mimicking the intracellular environment due to competitive coordination and subsequent micellar de-crosslinking. Because of their straightforward preparation and favorable drug release characteristics, core-crosslinked Lx PEG-P(HPMA) micelles hold promise as a versatile nanomedicine platform.

Polyselenoureas via Multicomponent Polymerizations Using Elemental Selenium as Monomer

Multicomponent polymerizations (MCPs) have emerged as a powerful tool in the synthesis of advanced, sequence-regulated polymers based on their mild reaction conditions, ease of use, and high atom economy. Herein, we exploit MCP methodology to introduce elemental selenium into a polymer chain, accessing a unique polymer class,i.e., polyselenoureas. These polyselenoureas can be synthesized from a broad range of commercially available starting materials, in a simple ambient temperature one-step procedure. The incorporation of selenium directly into the polymer backbone provides a unique handle for polymer characterization based on the distinctive isotope profiles exposed by high-resolution mass spectrometry, along with diagnostic signals observed in infrared and X-ray photoelectron spectroscopies. In addition, diffusion ordered spectroscopy provides access to hydrodynamic diameter information on the generated unique polymer class.

Light-Responsive Nanoparticles for Highly Efficient Cytoplasmic Delivery of Anticancer Agents

Stimuli-responsive nanostructures have shown great promise for intracellular delivery of anticancer compounds. A critical challenge remains in the exploration of stimuli-responsive nanoparticles for fast cytoplasmic delivery. Herein, near-infrared (NIR) light-responsive nanoparticles were rationally designed to generate highly efficient cytoplasmic delivery of anticancer agents for synergistic thermo-chemotherapy. The drug-loaded polymeric nanoparticles of selenium-inserted copolymer (I/D-Se-NPs) were rapidly dissociated in several minutes through reactive oxygen species (ROS)-mediated selenium oxidation upon NIR light exposure, and this irreversible dissociation of I/D-Se-NPs upon such a short irradiation promoted continuous drug release. Moreover, I/D-Se-NPs facilitated cytoplasmic drug translocation through ROS-triggered lysosomal disruption and thus resulted in highly preferable distribution to the nucleus even in 5 min postirradiation, which was further integrated with light-triggered hyperthermia for achieving synergistic tumor ablation without tumor regrowth.

Selenium nanoparticles: potential in cancer gene and drug delivery

In recent decades, colloidal selenium nanoparticles have emerged as exceptional selenium species with reported chemopreventative and therapeutic properties. This has sparked widespread interest in their use as a carrier of therapeutic agents with results displaying synergistic effects of selenium with its therapeutic cargo and improved anticancer activity. Functionalization remains a critical step in selenium nanoparticles' development for application in gene or drug delivery. In this review, we highlight recent developments in the synthesis and functionalization strategies of selenium nanoparticles used in cancer drug and gene delivery systems. We also provide an update of recent preclinical studies utilizing selenium nanoparticles in cancer therapeutics.

Selenium borohydride reaction as a versatile platform for the straightforward preparation of selenide-containing topological polymers

A simple and versatile method for preparing selenide-containing polymers with desired topologies is established based on the reaction of a selenide-functionalized borohydride exchange resin with end-functionalized polymers.

Multi-hierarchical responsive polymers: stepwise oxidation of a selenium- and tellurium-containing block copolymer with sensitivity to both chemical and electrochemical stimuli

A multi-hierarchical responsive selenium- and tellurium-containing block copolymer that can be stepwise oxidized by both chemical methods and electrochemical methods.

Glutathione responsive polymers and their application in drug delivery systems

Materials which respond to biological cues are the subject of intense research interest due to their possible application in smart drug delivery vehicles.

A redox-responsive selenium-containing pillar[5]arene-based macrocyclic amphiphile: synthesis, controllable self-assembly in water, and application in controlled release

A selenium-containing pillar[5]arene-based macrocyclic amphiphile was prepared. This amphiphile self-assembled in water to form vesicles with redox responsiveness. Then, these pillar[5]arene-based vesicles were used in the controlled release of DOX.

Ultrasensitive GSH-Responsive Ditelluride-Containing Poly(ether-urethane) Nanoparticles for Controlled Drug Release

A novel ultrasensitive redox-responsive system for the controlled release of doxorubicin (DOX) was fabricated by ditelluride-containing poly(ether-urethane) copolymers. In this study, the ditelluride group was introduced for the first time into water-soluble copolymers used for drug delivery. Doxorubicin loaded in the copolymer nanoparticles can be released in a controlled manner through the cleavage of ditelluride bonds by glutathione (GSH). The ditelluride-containing poly(ether-urethane) nanoparticles were demonstrated to be biocompatible as drug delivery vehicles, therefore opening a new avenue in drug delivery systems for chemotherapy. Furthermore, the in vitro and in vivo studies revealed that the DOX-loaded ditelluride-containing poly(ether-urethane) nanoparticles exhibited efficient uptake in cancer cells, specific tumor targeting and antitumor activity, indicating their excellent potential as novel nanocarriers for drug delivery and cancer therapy.

Metal-containing and related polymers for biomedical applications

A survey of the most recent progress in the biomedical applications of metal-containing polymers is given. Due to the unique optical, electrochemical, and magnetic properties, at least 30 different metal elements, most of them transition metals, are introduced into polymeric frameworks for interactions with biology-relevant substrates via various means. Inspired by the advance of metal-containing small molecular drugs and promoted by the great progress in polymer chemistry, metal-containing polymers have gained momentum during recent decades. According to their different applications, this review summarizes the following biomedical applications: (1) metal-containing polymers as drug delivery vehicles; (2) metal-containing polymeric drugs and biocides, including antimicrobial and antiviral agents, anticancer drugs, photodynamic therapy agents, radiotherapy agents and biocides; (3) metal-containing polymers as biosensors, and (4) metal-containing polymers in bioimaging.

Selenium-Containing Amphiphiles Reduced and Stabilized Gold Nanoparticles: Kill Cancer Cells via Reactive Oxygen Species

Selenium has attracted increasing interest in recent decades because of the function of regulating the redox balance in the human body. However, biomedical studies of selenium are still limited. Gold nanoparticles (AuNPs), typically prepared by a first reduction step followed by a second stabilization step, are widely applied in biomedical studies. However, their own anticancer activity is less studied. Here, we report 2 nm AuNPs with significant anticancer activity (IC50 = 20 μM) that is stabilized by a selenium-containing amphiphile EGSe-tMe. The AuNPs are prepared by simply mixing chloroauric acid (HAuCl4) with EGSe-tMe, which acts as both a reducing agent and a stabilizer. In contrast to AuNPs prepared by EGSe-tMe, EGSe-tMe alone and typically prepared AuNPs show little anticancer activity even at concentrations up to 250 μM. Mechanistic studies suggest that selenium in cooperation with AuNPs can induce high concentrations of reactive oxygen species (ROS) in cancer cells, leading to cellular apoptosis.

Selenium-Platinum Coordination Dendrimers with Controlled Anti-Cancer Activity

Dendrimers are considered as good vectors for drug delivery in cancer treatment. However, most anticancer drugs are conjugated to the peripheral surface of dendrimers, sacrificing the advantages of monodispersity and stability belonging to dendrimers. Furthermore, dendrimers in current studies of cancer treatment are mostly used as vectors for drugs, whereas the anticancer activity of dendrimers on their own is less studied. Here we have prepared monodisperse selenium-platinum coordination dendrimers with a selenium-platinum core buried inside. Structures of the dendrimers were determined by various characterizations. The coordination dendrimers showed controlled anticancer activity by themselves, without loading additional drugs. The in vivo study further demonstrated their anticancer activity and low toxicity to normal tissues.

Dynamic Chemistry of Selenium: Se-N and Se-Se Dynamic Covalent Bonds in Polymeric Systems

The application of selenium in the responsive polymer system and the enzyme mimic system have been well studied. Our group initiated this line of research in 2009 by first extending selenium chemistry to dynamic chemistry. In this article, the discovery, progress, and application of selenium-related dynamic covalent bonds will be introduced. The dynamic property of Se-N bond and Se-Se bond were revealed and have been applied in the polymer system as enzyme mimic and self-healing materials, respectively. Further studies that need to be done and potential application of selenium-related dynamic chemistry will also be discussed.

Tellurium-containing nanoparticles for controlled delivery of cisplatin based on coordination interaction

Tellurium containing nanoparticles were designed and synthesized for the delivery of cisplatin.

Visible-Light-Induced Self-Healing Diselenide-Containing Polyurethane Elastomer

Visible light is an easily achievable and mild trigger for self-healing materials. By incorporating dynamic diselenide bonds into polyurethane, visible-light-induced self-healing materials can be fabricated. Besides mild visible light, the healing process can also be realized using directional laser irradiation, which makes the system a remotely controllable self-healing system.

Selenium-containing thermogel for controlled drug delivery by coordination competition

A coordination-responsive selenium-containing thermogel was designed and synthesized for controlled cisplatin delivery by competitive coordination of glutathione, which broadens the strategy of tuning drug release using thermogelling systems.

A γ-ray and dual redox-responsive supramolecular polymer constructed by a selenium containing pillar[5]arene dimer and a neutral guest

A novel linear supramolecular polymer was fabricated by self-assembly of a selenium containing pillar[5]arene dimer 1 and a neutral guest 2. This supramolecular polymer can be destroyed by irradiating γ-radiation, or adding H₂O₂ or GSH.

Coordination responsive tellurium-containing multilayer film for controlled delivery

A coordination-responsive tellurium-containing film was fabricated to load cisplatin by Te–Pt coordination, and competitive bio-ligands could trigger the release of cisplatin.