Pillararene-Based Stimuli-Responsive Supramolecular Delivery Systems for Cancer Therapy

Cancer poses a significant challenge to global public health, seriously threatening human health and life. Although various therapeutic strategies, such as chemotherapy (CT), radiotherapy, phototherapy, and starvation therapy, are applied to cancer treatment, their limited therapeutic effect, severe side effects, and unsatisfactory drug release behavior need to be carefully considered. Thus, there is an urgent need to develop efficient drug delivery strategies for improving cancer treatment efficacy and realizing on-demand drug delivery. Notably, pillararenes, as an emerging class of supramolecular macrocycles, possess unique properties of highly tunable structures, superior host-guest chemistry, facile modification, and good biocompatibility, which are widely used in cancer therapy to achieve controllable drug release and reduce the toxic side effects on normal tissues under various internal/external stimuli conditions. This review summarizes the recent advance of stimuli-responsive supramolecular delivery systems (SDSs) based on pillararenes for tumor therapy from the perspectives of different assembly methods and hybrid materials, including molecular-scale SDSs, supramolecular nano self-assembly delivery systems, and nanohybrid SDSs. Moreover, the prospects and critical challenges of stimuli-responsive SDSs based on pillararenes for cancer therapy are also discussed.

A Paramagnetic Metal-Organic Framework Enhances Mild Magnetic Hyperthermia Therapy by Downregulating Heat Shock Proteins and Promoting Ferroptosis via Aggravation of Two-Way Regulated Redox Dyshomeostasis

Mild magnetic hyperthermia therapy (MMHT) holds great potential in treating deep-seated tumors, but its efficacy is impaired by the upregulation of heat shock proteins (HSPs) during the treatment process. Herein, Lac-FcMOF, a lactose derivative (Lac-NH2 ) modified paramagnetic metal-organic framework (FcMOF) with magnetic hyperthermia property and thermal stability, has been developed to enhance MMHT therapeutic efficacy. In vitro studies showed that Lac-FcMOF aggravates two-way regulated redox dyshomeostasis (RDH) via magnetothermal-accelerated ferricenium ions-mediated consumption of glutathione and ferrocene-catalyzed generation of ∙OH to induce oxidative damage and inhibit heat shock protein 70 (HSP70) synthesis, thus significantly enhancing the anti-cancer efficacy of MMHT. Aggravated RDH promotes glutathione peroxidase 4 inactivation and lipid peroxidation to promote ferroptosis, which further synergizes with MMHT. H22-tumor-bearing mice treated with Lac-FcMOF under alternating magnetic field (AMF) demonstrated a 90.4% inhibition of tumor growth. This work therefore provides a new strategy for the simple construction of a magnetic hyperthermia agent that enables efficient MMHT by downregulating HSPs and promoting ferroptosis through the aggravation of two-way regulated RDH.

Multifunctional Supramolecular Vesicles as Zn2+ -Triggered Microglial Modulator Alleviates Alzheimer's Disease

Zn2+ -induced β-amyloid protein (Aβ) aggregation and microglia activation are the predominant contributors in Alzheimer's disease (AD). Regulating intracephalic excessive Zn2+ is a promising therapeutic strategy for AD treatment. However, only inhibition of Zn2+ is hardly to repair continuous damages caused by activated microglia. Herein, an intelligent resveratrol-loaded supramolecular vesicles (RES-loaded vesicles) with zinc ion chelation function and responsive release capability are constructed to alleviate Aβ fibrillation, oxidative stress, and microglial dysfunction. The resveratrol encapsulation efficiency and drug loading efficiency are calculated to be 49.67% and 7.87%, respectively. In vitro studies demonstrate that the RES-loaded vesicles can modulate Zn2+ -dependent Aβ aggregation. More importantly, the cargoes will be released in zinc environment and further reprograms microglia from proinflammatory M1 phenotype toward anti-inflammatory M2 phenotype, which prevents spontaneous neuroinflammation and alleviates cytotoxicity of cultured cells from 29% to 12%. With the stereotactic or intranasal administration, RES-loaded vesicles can overcome the blood brain barrier, alleviate neuronal apoptosis, neuroinflammation, and ultimately ameliorate cognitive impairment in two AD mouse models. This work provides a new sight for taking advantage of Zn2+ to treat CNS disorders.

Cancer Cell-Specific Fluorescent Prodrug Delivery Platforms

Targeting cancer cells with high specificity is one of the most essential yet challenging goals of tumor therapy. Because different surface receptors, transporters, and integrins are overexpressed specifically on tumor cells, using these tumor cell-specific properties to improve drug targeting efficacy holds particular promise. Targeted fluorescent prodrugs not only improve intracellular accumulation and bioavailability but also report their own localization and activation through real-time changes in fluorescence. In this review, efforts are highlighted to develop innovative targeted fluorescent prodrugs that efficiently accumulate in tumor cells in different organs, including lung cancer, liver cancer, cervical cancer, breast cancer, glioma, and colorectal cancer. The latest progress and advances in chemical design and synthetic considerations in fluorescence prodrug conjugates and how their therapeutic efficacy and fluorescence can be activated by tumor-specific stimuli are reviewed. Additionally, novel perspectives are provided on strategies behind engineered nanoparticle platforms self-assembled from targeted fluorescence prodrugs, and how fluorescence readouts can be used to monitor the position and action of the nanoparticle-mediated delivery of therapeutic agents in preclinical models. Finally, future opportunities for fluorescent prodrug-based strategies and solutions to the challenges of accelerating clinical translation for the treatment of organ-specific tumors are proposed.

Pillar[n]arene-calix[m]arene hybrid macrocyclic structures

To reserve planar chirality, enhance molecular recognition, and build advanced self-assemblies, hybrid macrocyclic hosts containing rigid pillar[n]arene and flexible calix[m]arene were designed, prepared and investigated for interesting applications. This review summarizes and discusses different synthetic strategies for constructing hybrid macrocyclic structures. Pillar[n]arene dimer with rigid aromatic double bridges provided the possibility of introducing calix[m]arene cavities, where the planar chirality was reserved in the structure of pillararene. The capacity for molecular recognition was enhanced by hybrid macrocyclic cavities. Interestingly, the obtained pillar[n]arene-calix[m]arene could self-assemble into "channels" and "honeycomb" in both the solid state and solution phase as well as donate the molecular architecture as the wheel for the formation of mechanically interlocked molecules, such as rotaxane. In addition, the pillar[n]arene and calix[m]arene could also be coupled together to produce pillar[n]arene embeded 1,3-alternate and cone conformational calix[m]arene derivatives, which could catalyze the oxidative polymerization of aniline in aqueous solutions. Except for building hybrid cyclophanes by covalent bonds, weak supramolecular interactions were used to prepare pillar[n]arene-calix[m]arene analogous composites with other pillar-like pillar[n]pyridiniums and calix-like calix[m]pyrroles, exhibiting reasonable performances in enhancing molecular recognition and trapping solvent molecules.

Glycomacromolecules: Addressing challenges in drug delivery and therapeutic development

Carbohydrate-based materials offer exciting opportunities for drug delivery. They present readily available, biocompatible components for the construction of macromolecular systems which can be loaded with cargo, and can enable targeting of a payload to particular cell types through carbohydrate recognition events established in biological systems. These systems can additionally be engineered to respond to environmental stimuli, enabling triggered release of payload, to encompass multiple modes of therapeutic action, or to simultaneously fulfil a secondary function such as enabling imaging of target tissue. Here, we will explore the use of glycomacromolecules to deliver therapeutic benefits to address key health challenges, and suggest future directions for development of next-generation systems.

Tumor microenvironment responsive supramolecular glyco-nanovesicles based on diselenium-bridged pillar[5]arene dimer for targeted chemotherapy

Supramolecular glyco-nanovesicles (SeSe-(P5)2⊃Man-NH3+) based on the host-guest complex of a diselenium-bridged pillar[5]arene dimer and a mannose derivative have been successfully developed for the first time, which possessed tumor microenvironment-responsiveness and specific targetability due to their diselenium bonds and mannose units, respectively.

Supramolecular Vesicles Based on Amphiphilic Pillar[n]arenes for Smart Nano-Drug Delivery

Supramolecular vesicles are the most popular smart nano-drug delivery systems (SDDs) because of their unique cavities, which have high loading carrying capacity and controlled-release action in response to specific stimuli. These vesicles are constructed from amphiphilic molecules via host-guest complexation, typically with targeted stimuli-responsive units, which are particularly important in biotechnology and biomedicine applications. Amphiphilic pillar[n]arenes, which are novel and functional macrocyclic host molecules, have been widely used to construct supramolecular vesicles because of their intrinsic rigid and symmetrical structure, electron-rich cavities and excellent properties. In this review, we first explain the synthesis of three types of amphiphilic pillar[n]arenes: neutral, anionic and cationic pillar[n]arenes. Second, we examine supramolecular vesicles composed of amphiphilic pillar[n]arenes recently used for the construction of SDDs. In addition, we describe the prospects for multifunctional amphiphilic pillar[n]arenes, particularly their potential in novel applications.

Host–guest interaction based supramolecular photodynamic therapy systems: a promising candidate in the battle against cancer

This article summarizes recent advances in the development of supramolecular photodynamic therapy based on host–guest interactions.

Enzyme-responsive fluorescent camptothecin prodrug/polysaccharide supramolecular assembly for targeted cellular imaging and in situ controlled drug release

An enzyme-responsive polysaccharide assembly was constructed, which possesses low cytotoxicity, targeted imaging and controlled drug release, while providing a concurrent means for the real-time tracking of drug delivery.

Recent advances in metallopolymer-based drug delivery systems

Metallopolymers (MPs) or metal-containing polymers have shown great potential as new drug delivery systems (DDSs) due to their unique properties, including universal architectures, composition, properties and surface chemistry. Over the past few decades, the exponential growth of many new classes of MPs that deal with these issues has been demonstrated. This review presents and assesses the recent advances and challenges associated with using MPs as DDSs. Among the most widely used MPs for these purposes, metal complexes based on synthetic and natural polymers, coordination polymers, metal-organic frameworks, and metallodendrimers are distinguished. Particular attention is paid to the stimulus- and multistimuli-responsive metallopolymer-based DDSs. Of considerable interest is the use of MPs for combination therapy and multimodal systems. Finally, the problems and future prospects of using metallopolymer-based DDSs are outlined. The bibliography includes articles published over the past five years.

Glutathione-Priming Nanoreactors Enable Fluorophore Core/Shell Transition for Precision Cancer Imaging

In an attempt to develop an imaging probe with ultra-high sensitivity for a broad range of tumors in vivo and inspired by the concept of chemical synthetic nanoreactors, we designed a type of glutathione-priming fluorescent nanoreactor (GPN) with an albumin-coating shell and hydrophobic polymer core containing disulfide bonds, protonatable blocks, and indocyanine green (ICG), a near-infrared fluorophore. The albumin played multiple roles including biocompatible carriers, hydrophilic stabilizer, "receptor" of the fluorophores, and even targeting molecules. The protonation of the hydrophobic core triggered the outside-to-core transport of acidic glutathione (GSH), as well as the core-to-shell transference of ICGs after the disulfide bond cleavage by GSH, which induced strong binding of fluorophores with albumins on the GPN shell, initiating intensive fluorescence signals. As a result, the GPNs demonstrated extremely high response sensitivity and imaging contrast, proper time window, and broad cancer specificity. In fact, an orthogonal activation pattern was found in vitro with an ON/OFF ratio up to 24.7-fold. Furthermore, the nanoprobes specifically amplified the tumor signals in five cancer-bearing mouse models and actualized tumor margin delineation with a contrast up to 20-fold, demonstrating much better imaging efficacy than the other four commercially available probes. Therefore, the GPNs provide a new paradigm in developing high-performance bioresponsive nanoprobes.

Molecular Programming of Biodegradable Nanoworms via Ionically Induced Morphology Switch toward Asymmetric Therapeutic Carriers

Engineering biodegradable nanostructures with precise morphological characteristics is a key objective in nanomedicine. In particular, asymmetric (i.e., nonspherical) nanoparticles are desirable due to the advantageous effects of shape in a biomedical context. Using molecular engineering, it is possible to program unique morphological features into the self-assembly of block copolymers (BCPs). However, the criteria of biocompatibility and scalability limit progress due to the prevalence of nondegradable components and the use of toxic solvents during fabrication. To address this shortfall, a robust strategy for the fabrication of morphologically asymmetric nanoworms, comprising biodegradable BCPs, has been developed. Modular BCPs comprising poly (ethylene glycol)-block-poly(caprolactone-gradient-trimethylene carbonate) (PEG-PCLgTMC), with a terminal chain of quaternary ammonium-TMC (PTMC-Q), undergo self-assembly via direct hydration into well-defined nanostructures. By controlling the solution ionic strength during hydration, particle morphology switches from spherical micelles to nanoworms (of varying aspect ratio). This ionically-induced switch is driven by modulation of chain packing with salts screening interchain repulsions, leading to micelle elongation. Nanoworms can be loaded with cytotoxic cargo (e.g., doxorubicin) at high efficiency, preferentially interact with cancer cells, and increase tumor penetration. This work showcases the ability to program assembly of BCPs and the potential of asymmetric nanosystems in anticancer drug delivery.

Host-Guest Chemistry in Supramolecular Theranostics

Macrocyclic hosts, such as cyclodextrins, calixarenes, cucurbiturils, and pillararenes, exhibit unparalleled advantages in disease diagnosis and therapy over the past years by fully taking advantage of their host-guest molecular recognitions. The dynamic nature of the non-covalent interactions and selective host-guest complexation endow the resultant nanomaterials with intriguing properties, holding promising potentials in theranostic fields. Interestingly, the differences in microenvironment between the abnormal and normal cells/tissues can be employed as the stimuli to modulate the host-guest interactions, realizing the purpose of precise diagnosis and specific delivery of drugs to lesion sites. In this review, we summarize the progress of supramolecular theranostics on the basis of host-guest chemistry benefiting from their fantastic topological structures and outstanding supramolecular chemistry. These state-of-the-art examples provide new methodologies to overcome the obstacles faced by the traditional theranostic systems, promoting their clinical translations.

A multifunctional supramolecular vesicle based on complex of cystamine dihydrochloride capped pillar[5]arene and galactose derivative for targeted drug delivery

Background: Supramolecular vesicles are a novel class of nanocarriers that have great potential in biomedicine.Methods: A multifunctional supramolecular vesicle (CAAP5G) based on the complex of CAAP5 and galactose derivative (G) assembled via host-guest interaction was constructed. Results: Using Human embryonic kidney T (293T) cells as experimental models, the cytotoxic effects of CAAP5G was investigated to 0-50 µmol/L for 24 h. Notably, the CAAP5G vesicles revealed low-toxicity to 293T cells, it was critical to designing drug nano-carriers. Simultaneously, we have evaluated doxorubicin hydrochloride (DOX)-loaded CAAP5G vesicles anticancer efficiency, where DOX-loaded CAAP5G vesicles and free DOX incubated with Human hepatocellular carcinoma cancer cell (HpeG2 cells) and 293T cells for 24 h, 48 h, 72 h. It turned out that CAAP5G vesicles encapsulated anticancer drug (DOX) could decrease DOX side-effect on 293T cells and increase DOX anticancer efficiency. More importantly, the cysteamine as an adjuvant chemotherapy drug was released from CAAP5G vesicles in HepG2 cells where a higher GSH concentration exists. The adjuvant chemotherapy efficiency was evaluated, where free DOX and DOX-loaded CAAP5G vesicles incubated with DOX-resistance HepG2 cells (HepG2-ADR cells) for 24, 48, 72 h, respectively. Conclusion: The results revealed that the DOX encapsulated by CAAP5G vesicles could enhance the cytotoxicity of DOX and provide insights for designing advanced nano-carriers toward adjuvant chemotherapies.

Supramolecular vesicles based on pillar[n]arenes: design, construction, and applications

Supramolecular vesicles have attracted considerable attention due to their advantages of facile construction, high-cargo-loading capacity, and good biocompatibility. Pillar[n]arenes are a unique family of supramolecular macrocycles, exhibiting excellent features and broad applications due to their intrinsic topology and high functionality. In the past decade, the construction of pillar[n]arene-based supramolecular vesicles has been continuously attempted and developed rapidly. In this review, we mainly summarize the significant advancements of such supramolecular vesicles in the last three years. By showing some representative examples, the design strategies, construction methods, and potential applications of these dynamic nanocarriers are discussed in detail. In particular, the responsiveness of such vesicles to various external stimuli and their applications in drug delivery are highlighted. The outstanding performance of pillar[n]arene-based supramolecular vesicles would definitely enrich the family of supramolecular vesicles and promote the development of dynamic supramolecular materials.

Stimuli-responsive supramolecular nano-systems based on pillar[n]arenes and their related applications

Stimuli-responsive supramolecular nano-systems (SRNS) have been a trending interdisciplinary research area due to the responsiveness upon appropriate stimuli, which makes SRNS very attractive in multiple fields where precise control is vital.

Supramolecular delivery systems based on pillararenes

Supramolecular delivery systems (SDSs) fabricated via molecular assembly, which conveniently allow integration of multiple functions in a single system and structural diversity of systems, are a very active research area due to their enormous potential in biomedical applications, including drug delivery, cell imaging, diagnosis, and release monitoring. Pillararenes, a novel type of macrocyclic molecule, are gaining increasing interest as an important component in the construction of SDSs due to their unique structural and chemical properties. This feature article summarizes pillararene-based SDSs constructed via host-guest interactions via four strategies: (1) supramolecular host-guest complexation; (2) self-assembly of supramolecular amphiphiles; (3) self-assembly of amphiphilic supramolecular polymer conjugates; (4) hybridization with other porous materials, such as inorganic materials and metal-organic frameworks (MOFs). The various SDSs based on pillararenes for the delivery of different cargoes from anti-cancer drugs, fluorescent molecules, siRNAs, and insulin to antibiotics are reviewed. Furthermore, future challenges for advanced SDSs based on pillararenes and their broader applications are outlined.

A dual redox-responsive supramolecular amphiphile fabricated by selenium-containing pillar[6]arene-based molecular recognition

A dual redox-responsive pillar[6]arene-based supramolecular amphiphile was fabricated in water. The self-assembly behavior of this supramolecular amphiphile in response to dual redox stimuli was investigated.

A supramolecular hybrid material constructed from pillar[6]arene-based host-guest complexation and ZIF-8 for targeted drug delivery

A novel supramolecular hybrid material ZIF-8@DOX@WP6@G constructed from the host-guest complexation between carboxylated pillar[6]arene (WP6) and a galactose derivative (G), and doxorubicin (DOX)-loaded ZIF-8 has been synthesized for targeted drug delivery. The results showed that ZIF-8@DOX@WP6@G not only maintained the pH-sensitive drug release properties of ZIF-8 but also exhibited excellent water dispersibility and selective toxicity for hepatoma cancer cells due to the assembly of WP6 and G. The strategy used in this study opens up a new avenue for constructing multifunctional supramolecular hybrid materials for therapeutic applications in cancer treatment.

Supramolecular Nanosystem Based on Pillararene-Capped CuS Nanoparticles for Targeted Chemo-Photothermal Therapy

A smart supramolecular nanosystem integrating targeting, chemotherapy, and photothermal therapy was constructed based on carboxylatopillar[5]arene (CP[5]A)-functionalized CuS nanoparticles (CuS@CP NPs). CuS@CP NPs with good monodispersibility and strong near-infrared absorption were synthesized in aqueous solution through a facile one-pot supramolecular capping method, followed by surface installation of a liver cancer-targeted galactose derivative through host-guest binding interaction. The resulting smart supramolecular nanosystem, namely, CuS@CPG, exhibited excellent photothermal ablation capability to HepG2 cells upon irradiation with laser at 808 nm. Chemotherapeutic drug, doxorubicin hydrochloride (DOX), was further loaded on CuS@CPG via electrostatic interactions between positively charged DOX and negatively charged CP[5]A to give CuS@CPG-DOX with a high drug-loading capacity up to 48.4%. The weakening of DOX-CP[5]A interactions in an acidic environment promoted the pH-responsive drug release from CuS@CPG-DOX. Significantly, this multifunctional supramolecular nanosystem showed a remarkably enhanced therapeutic effect through the combination of targeted chemotherapy and photothermal therapy upon in vitro cell study. Moreover, preliminary in vivo study demonstrated that CuS@CPG and CuS@CPG-DOX had good biocompatibility and excellent tumor inhibition effects upon near-infrared laser irradiation.

Pillararene-based self-assembled amphiphiles

Pillararenes are a unique group of supramolecular macrocycles, presenting important features and potential applications on account of their intrinsic structural properties and functionality. Developing pillararene-based self-assembled amphiphiles (PSAs) is an efficient approach to translate pillararenes into functional systems and materials for facilitating their practical applications. In this review article, we highlight recent significant advancements in PSAs. A new standard according to the number, solubility, and amphiphilicity of building blocks is employed for dividing PSAs into different categories. The fabrication of PSAs based on various building blocks and supramolecular interactions, and the formation of amphiphile-based self-assemblies are then discussed based on this standard. Furthermore, interesting stimulus-responsiveness to various factors, such as pH, redox, temperature, light, ionic effect, and host-guest competition, generated by the functional groups on various building blocks is summarized, and the corresponding supramolecular interactions in PSAs and their self-assemblies are elaborated. In addition, some important applications of PSAs and their assemblies are discussed. This review not only provides fundamental findings on the construction of PSAs, but also foresees future research directions in this rapidly developing area.

pH-Induced Charge-Reversal Amphiphile with Cancer Cell-Selective Membrane-Disrupting Activity

A charge-reversal amphiphile exhibiting charge conversion from negative to positive induced by pH is reported. It selectively kills cancer cells through cell membrane disruption. This amphiphile comprising an alkyl chain and anionic headgroup of acid-labile β-carboxylic amide (C16N-DCA) was prepared. In the microenvironment of normal cells with pH 7.4, the negatively charged C16N-DCA exhibited considerably reduced cytotoxicity. However, in the acidic microenvironment of cancer cells with pH 6.5-6.8, the headgroup charge of C16N-DCA changed from negative to positive under hydrolysis of the acid-labile amide group. As a result, the generated cationic amphiphile displayed significant killing of cancer cells by disrupting their cell membranes. Such pH-selective cell killing bioactivity represents a new route of chemotherapy for anticancer strategies.

A supramolecular photosensitizer system based on the host-guest complexation between water-soluble pillar[6]arene and methylene blue for durable photodynamic therapy

A supramolecular photosensitizer system WP6-MB was synthesized based on water-soluble pillar[6]arene and the photosensitizer methylene blue (MB) via host-guest interaction. MB can complex with WP6 directly with a high complex constant without further modification. In particular, WP6-MB can reduce the dark toxicity of MB remarkably. Furthermore, it can efficiently overcome photobleaching and extend the time for singlet oxygen production of MB upon light irradiation, which is significant for durable photodynamic therapy.

Dual-responsive dithio-polydopamine coated porous CeO2 nanorods for targeted and synergistic drug delivery

Objective

The aim was to produce the first report of assembling degradable stimuli-responsive dithio-polydopamine coating with a cancer target unit for synergistic and targeted drug delivery.

Methods

A multifunctional drug delivery system was constructed by coating a dual-responsive dithio-polydopamine (PDS) on porous CeO₂ nanorods and subsequent conjugation of lactose derivative, where the PDS was formed by self-polymerization of dithio-dopamine (DOPASS).

Results

The multifunctional drug delivery system displayed excellent cancer targeted ability resulting from the conjugation of lactose derivative, which could specifically recognize the overexpressed asialoglycoprotein receptors on the surface of HepG2 cells. It also showed a dual-responsive property of glutathione and pH, achieving controllable drug release from the cleavage of disulfide bond and subsequent degradation of PDS in cancer cells. Moreover, the degradation of PDS led to the exposure of CeO₂ nanorods, which has a synergistic anticancer effect due to its cytotoxicity to cancer cells.

Conclusion

This work presents a good example of a rational design towards synergistic and targeted DDS for cancer chemotherapies.

A mitochondria-targeting supramolecular photosensitizer based on pillar[5]arene for photodynamic therapy

A mitochondria-targeting supramolecular photosensitizer system TPP-QAS/WP5/DTAB was constructed based on a host-guest inclusion complex. The supramolecular system could efficiently release and activate TPP-QASs in an acidic environment, which have been demonstrated to preferentially accumulate in mitochondria. Singlet oxygen (¹O₂) could be in situ generated in mitochondria under light irradiation, further enhancing the PDT efficacy.

Complex Consisting of β-Glucan and Antigenic Peptides with Cleavage Site for Glutathione and Aminopeptidases Induces Potent Cytotoxic T Lymphocytes

The efficient induction of antigen-specific immune responses requires not only promotion of the uptake of antigens and adjuvant molecules into antigen-presenting cells but also control of their intracellular behavior. We previously demonstrated that the β-glucan schizophyllan (SPG) can form complexes with CpG oligonucleotides with attached dA₄₀ (CpG-dA/SPG), which can accumulate in macrophages in the draining inguinal lymph nodes and induce strong immune responses. In this study, we prepared various conjugates composed of antigenic peptide (OVA_257-264) and dA₄₀ and made complexes with SPG. The conjugates with a disulfide bond between OVA_257-264 and dA₄₀ were easily cleaved by glutathione. The resultant peptides with a hydrophobic amino acid at the C-terminal end was recognized by puromycin-insensitive leucine aminopeptidase (PILS-AP), which trims antigenic peptide precursors and prepares peptides of eight or nine amino acids in length, which is the optimal length for binding to major histocompatibility complex (MHC)-I. The conjugate exposed to such enzymes induced a high antigen presentation level. The antigen presentation level was almost the same before and after the complexation with SPG. Immunization with a mixture of dA-OVA_257-264/SPG and CpG-dA/SPG induced high antigen-specific cytotoxic T-lymphocyte activity at a much lower peptide dose than in previous studies. These results can be strongly ascribed to not only the cell-specific delivery by SPG but also the control of the intracellular behavior by the introduction of cleavage sites. Therefore, peptide-dA/SPG complexes could be used as potent vaccine antigens for the treatment of cancers and infectious diseases.

Synergistic and targeted drug delivery based on nano-CeO2 capped with galactose functionalized pillar[5]arene via host-guest interactions

A smart drug delivery system based on porous CeO₂ nano-rods (CeONRs) capped with galactose functionalized pillar[5]arene via host-guest interactions has been constructed, which showed GSH-responsiveness, synergism with anticancer drugs and cancer targeting ability resulting from its disulphide unit, ceria properties and galactose units, respectively.

A water-soluble pillar[5]arene-based chemosensor for highly selective and sensitive fluorescence detection of l-methionine

Cationic pillar[5]arene (AWP5) was employed as a water-soluble chemosensor for recognition of amino acids. AWP5 could fluorescently detect l-methionine in water with high selectivity and sensitivity.

In situ supramolecular polymerization promoted by the marriage of dynamic covalent bonding and pillar[5]arene-based host–guest interaction

A temperature and pH dual-responsive linear supramolecular polymer was efficiently constructed by unifying dynamic covalent bonding and pillar[5]arene-based host–guest interaction through in situ supramolecular polymerization.

Recent Advances in Stimuli-Responsive Release Function Drug Delivery Systems for Tumor Treatment

Benefiting from the development of nanotechnology, drug delivery systems (DDSs) with stimuli-responsive controlled release function show great potential in clinical anti-tumor applications. By using a DDS, the harsh side effects of traditional anti-cancer drug treatments and damage to normal tissues and organs can be avoided to the greatest extent. An ideal DDS must firstly meet bio-safety standards and secondarily the efficiency-related demands of a large drug payload and controlled release function. This review highlights recent research progress on DDSs with stimuli-responsive characteristics. The first section briefly reviews the nanoscale scaffolds of DDSs, including mesoporous nanoparticles, polymers, metal-organic frameworks (MOFs), quantum dots (QDs) and carbon nanotubes (CNTs). The second section presents the main types of stimuli-responsive mechanisms and classifies these into two categories: intrinsic (pH, redox state, biomolecules) and extrinsic (temperature, light irradiation, magnetic field and ultrasound) ones. Clinical applications of DDS, future challenges and perspectives are also mentioned.

Efficient sensing of fluoride ions in water using a novel water soluble self-assembled supramolecular sensor based on pillar[5]arene

By rationally introducing competitive coordination, the supramolecular sensors could reversibly sense Fe³⁺ and F⁻ in water with high selectivity and sensitivity.