Substitution Activated Precise Phototheranostics through Supramolecular Assembly of AIEgen and Calixarene

Supra-Hybrid Nanocarriers of Calix[4]Arene and PLGA for Enhanced Encapsulation and Extended Delivery of Gossypol in Cancer Therapy

In this study, supra-hybrid nanocarriers Cal-P NPs are developed by combining amphiphilic macrocyclic calix[4]arene and PLGA, offering adequate stability and multifunctionality as a single-platform nanocarrier resulting in monodispersed nanoparticles with unique synthetic tunability and an optimized hydrophobic core for therapeutic encapsulation. Unlike conventional multicomponent systems, the design eliminates the need for many external stabilizers while enabling tailored PEGylation for controlled drug release, as demonstrated with hydrophobic gossypol. This innovation addresses key limitations in cancer nanomedicine, including premature drug leakage and dose frequency, through a synthetically tunable and structurally optimized, bioresistant core. Gossypol, a model bioactive molecule with poor water solubility, is effectively loaded into the Cal-P NPs, significantly enhancing its aqueous solubility to millimolar concentrations. The encapsulation is driven by favorable interactions between gossypol and the hydrophobic groups of calixarene and PLGA, resulting in a stable core with sustained release properties. Validated through in vivo pharmacokinetic studies and detailed anticancer experiments in two distinct cancer cell lines, GP-Cal-P NPs demonstrated their potential as a robust platform for therapeutic delivery. These findings emphasize the versatility of Cal-P NPs in addressing challenges associated with hydrophobic drugs and highlight their promise for further preclinical and clinical development.

A pH-Sensitive Nanosized Covalent-Organic Polymer for Enhanced Tumor Photodynamic Immunotherapy by Hypoxia Relief and STAT3 Inhibition

Photodynamic therapy (PDT) is a promising cancer therapy modality by generating reactive oxygen species (ROS) and triggering immunogenic cell death. However, the therapeutic effect of PDT is strongly limited by tumor hypoxia and immunosuppressive landscape. Herein, a pH-sensitive nanosized covalent-organic polymer (COP), composed of the photosensitizer porphyrin and pyruvate kinase inhibitor vitamin K3 (VK3), is designed to overcome these issues. The signal transducer and activator of transcription 3 (STAT3) inhibitor WP1066 is further encapsulated into COPs to form a WP1066-loaded COP (TVW). As an inhibitor of pyruvate kinase, VK3 can reduce intracellular oxygen consumption by inhibiting the glycolytic pathway, leading to the alleviation of the tumor hypoxic microenvironment. The relief of tumor hypoxia by VK3 enhances photodynamic cytotoxicity by generating more ROS. Meanwhile, STAT3 acts as a major regulator of PD-L1, a key inhibitor that promotes immune escape. WP1066 effectively inhibits the expression of STAT3 and reduces PD-L1 expression, thereby significantly inhibiting tumor immune escape and enhancing antitumor efficacy in a synergistic manner. The antitumor capacity of photodynamic immunotherapy is extensively investigated in a murine subcutaneous hepatocellular carcinoma model. This photo-immunotherapy may provide an effective combination regimen for the efficient treatment of solid tumors such as hepatocellular carcinoma.

Photoinduced Proton-Transfer-Mediated Molecular Recognition in Molecular Crystals

Molecular recognition has traditionally been focused on ground-state interactions. However, leveraging photoenergy to access excited-state molecular recognition, which may enable enhanced sensitivity or selectivity that is unattainable in the ground state, remains underexplored. In this study, we demonstrate a novel photoinduced molecular recognition mechanism using self-assembled crystalline microribbons composed of a donor-acceptor (D-A) molecule with a twisted molecular backbone for ultratrace phenol vapor detection. We confirm that photoinduced proton transfer occurs from phenol to the C═N group in the pyridine moiety of the D-A system, generating a protonated D-A molecule and a phenoxide ion that triggers fluorescence quenching. This proton-transfer-mediated recognition mechanism endows the microribbons with exceptional sensitivity and selectivity toward phenol vapor, achieving a limit of detection (LOD) of 0.6 parts per trillion (ppt). Our findings reveal that harnessing light energy to drive molecular recognition opens new avenues for advancing fluorescence sensing technologies.

The Current Advances in Design Strategy (Indirect Strategy and Direct Strategy) for Type-I Photosensitizers

Type-I photosensitizers (PSs) are among the most potential candidates for photodynamic therapy (PDT), as their low dependence on oxygen endow them with many advantages for treating hypoxic tumor. However, most of the reported type-I PSs have a contingency of molecular design, because electron transfer (ET) reaction is more difficult to achieve than energy transfer (EET) process. Therefore, it is urgent to understand molecular design mechanisms for type-I PSs. In this review, the two ways to achieve the type-I PSs, i.e., inhibiting EET process (type-II) or enhancing ET process (type-I), are detailly explained. In response, the current design strategies of type-I PSs are summarized from two perspectives: indirect strategy (inhibiting EET process: reducing the energy of the lowest triplet excited state (T1) to lower than the energy required for the excitation energy transfer to produce singlet oxygen) and direct strategy (enhancing ET process: promoting the ET efficiency of PSs to generate superoxide radicals). The construction of direct strategy can be realized by forming an electron-rich microenvironment, providing an electron-deficient intermediate transmitter, and introducing an enhanced electron transfer capacity primitive.

Acid-responsive singlet oxygen nanodepots

The singlet oxygen carrier addresses the challenges of traditional photodynamic therapy (PDT), which relies on the presence of oxygen within solid tumors and struggles with light penetration issues. However, the inability to control the release of singlet oxygen has hindered precise treatment applications. Here, we introduce an acid-responsive singlet oxygen nanodepot (aSOND) designed to overcome this limitation. The aSOND is synthesized using a responsive diblock copolymer system that includes a hydrophilic PEG block and a pH-responsive block with singlet oxygen loading sites. In neutral or alkaline environments, the aSOND releases singlet oxygen slowly, ensuring stability in blood circulation. In contrast, in acidic environments such as the tumor microenvironment or intracellular lysosomes, protonation of the tertiary amine group within the pH responsive block increases the hydration of the polymer, triggering a rapid release of singlet oxygen. This feature enables controlled, tumor-specific release of reactive oxygen species (ROS). The aSOND system effectively implements an "OFF-ON" singlet oxygen therapy, demonstrating high spatiotemporal selectivity and independence from both oxygen supply and external light, offering a promising approach for targeted cancer therapy.

Recent Advances in Calixarene-Based Fluorescent Sensors for Biological Applications

Due to their structural features, macrocyclic compounds such as calixarenes, conjugated with a variety of fluorophores have led to the development of fluorescent probes for numerous applications. This review covers the recent advances (from 2009 to date) made in calixarene-based fluorescent sensors and their biological applications. In addition to the fluorescence mechanisms used to signal the analyte binding, this article focuses mainly on the detection of biological relevant ions, on the selective sensing of biomolecules, such as amino acids, enzymes, drugs and other organic compounds, and on intracellular imaging. Calixarene-containing fluorescent nanoparticles and nanoaggregates for imaging and drug delivery are also described. Finally, this review presents some conclusions and future perspectives in this field.

Recent Advances in Synthesis and Applications of Calixarene Derivatives Endowed with Anticancer Activity

Calix[n]arenes, macrocycles constituted of 4-8 phenol moieties linked through methylene bridges, are stable molecules that can be selectively functionalised at the upper or lower rim. It has already been demonstrated that calixarene derivatives can be biologically or pharmacologically active compounds. More recently, suitably functionalised calixarenes and calixarene analogues (dihomooxacalixarenes, thiacalixarenes, calix[4]resorcinols, azacalixarenes, calixpyrroles, and pillarenes) were found to act as anticancer agents, at least in in vitro assays. We are reporting on the latest progress in this research field.

Fluorinated macromolecular amphiphiles as prototypic molecular drones

The advent of drones has revolutionized various aspects of our lives, and in the realm of biological systems, molecular drones hold immense promise as "magic bullets" for major diseases. Herein, we introduce a unique class of fluorinated macromolecular amphiphiles, designed in the shape of jellyfish, serving as exemplary molecular drones for fluorine-19 MRI (19F MRI) and fluorescence imaging (FLI)-guided drug delivery, status reporting, and targeted cancer therapy. Functioning akin to their mechanical counterparts, these biocompatible molecular drones autonomously assemble with hydrophobic drugs to form uniform nanoparticles, facilitating efficient drug delivery into cells. The status of drug delivery can be tracked through aggregation-induced emission (AIE) of FLI and 19F MRI. Furthermore, when loaded with a heptamethine cyanine fluorescent dye IR-780, these molecular drones enable near-infrared (NIR) FL detection of tumors and precise delivery of the photosensitizer. Similarly, when loaded with doxorubicin (DOX), they enable targeted chemotherapy with fluorescence resonance energy transfer (FRET) FL for real-time status updates, resulting in enhanced therapeutic efficacy. Compared to conventional drug delivery systems, molecular drones stand out for their simplicity, precise structure, versatility, and ability to provide instantaneous status updates. This study presents prototype molecular drones capable of executing fundamental drone functions, laying the groundwork for the development of more sophisticated molecular machines with significant biomedical implications.

Supramolecular dye nanoassemblies for advanced diagnostics and therapies

Dyes have conventionally been used in medicine for staining cells, tissues, and organelles. Since these compounds are also known as photosensitizers (PSs) which exhibit photoresponsivity upon photon illumination, there is a high desire towards formulating these molecules into nanoparticles (NPs) to achieve improved delivery efficiency and enhanced stability for novel imaging and therapeutic applications. Furthermore, it has been shown that some of the photophysical properties of these molecules can be altered upon NP formation thereby playing a major role in the outcome of their application. In this review, we primarily focus on introducing dye categories, their formulation strategies and how these strategies affect their photophysical properties in the context of photothermal and non-photothermal applications. More specifically, the most recent progress showing the potential of dye supramolecular assemblies in modalities such as photoacoustic and fluorescence imaging, photothermal and photodynamic therapies as well as their employment in photoablation as a novel modality will be outlined. Aside from their photophysical activity, we delve shortly into the emerging application of dyes as drug stabilizing agents where these molecules are used together with aggregator molecules to form stable nanoparticles.

Programmable Singlet Oxygen Battery for Automated Photodynamic Therapy Enabled by Pyridone-Pyridine Tautomer Engineering

The efficacy of photodynamic therapy is hindered by the hypoxic environment in tumors and limited light penetration depth. The singlet oxygen battery (SOB) has emerged as a promising solution, enabling oxygen- and light-independent 1O2 release. However, conventional SOB systems typically exhibit an "always-ON" 1O2 release, leading to potential 1O2 leakage before and after treatment. This not only compromises therapeutic outcomes but also raises substantial biosafety concerns. In this work, we introduce a programmable singlet oxygen battery, engineered to address all the issues discussed above. The concept is illustrated through the development of a tumor-microenvironment-responsive pyridone-pyridine switch, PyAce, which exists in two tautomeric forms: PyAce-0 (pyridine) and PyAce (pyridone) with different 1O2 storage half-lives. In its native state, PyAce remains in the pyridone form, capable of storing 1O2 (t1/2 = 18.5 h). Upon reaching the tumor microenvironment, PyAce is switched to the pyridine form, facilitating rapid and thorough 1O2 release (t1/2 = 16 min), followed by quenched 1O2 release post-therapy. This mechanism ensures suppressed 1O2 production pre- and post-therapy with selective and rapid 1O2 release at the tumor site, maximizing therapeutic efficacy while minimizing side effects. The achieved "OFF-ON-OFF" 1O2 therapy showed high spatiotemporal selectivity and was independent of the oxygen supply and light illumination.

Recent Progress of Supramolecular Chemotherapy Based on Host-Guest Interactions

Chemotherapy is widely recognized as an effective approach for treating cancer due to its ability to eliminate cancer cells using chemotherapeutic drugs. However, traditional chemotherapy suffers from various drawbacks, including limited solubility and stability of drugs, severe side effects, low bioavailability, drug resistance, and challenges in tracking treatment efficacy. These limitations greatly hinder its widespread clinical application. In contrast, supramolecular chemotherapy, which relies on host-guest interactions, presents a promising alternative by offering highly efficient and minimally toxic anticancer drug delivery. In this review, an overview of recent advancements in supramolecular chemotherapy based on host-guest interactions is provided. The significant role it plays in guiding cancer therapy is emphasized. Drawing on a wealth of cutting-edge research, herein, a timely and valuable resource for individuals interested in the field of supramolecular chemotherapy or cancer therapy, is presented. Furthermore, this review contributes to the progression of the field of supramolecular chemotherapy toward clinical application.

Ligand Regulation Strategy to Modulate ROS Nature in a Rhodamine-Iridium(III) Hybrid System for Phototherapy

The efficacy of photodynamic therapy (PDT) is highly dependent on the photosensitizer features. The reactive oxygen species (ROS) generated by photosensitizers is proven to be associated with immunotherapy by triggering immunogenic cell death (ICD) as well. In this work, we establish a rhodamine-iridium(III) hybrid model functioning as a photosensitizer to comprehensively understand its performance and potential applications in photodynamic immunotherapy. Especially, the correlation between the ROS generation efficiency and the energy level of the Ir(III)-based excited state (T1'), modulated by the cyclometalating (C∧N) ligand, is systematically investigated and correlated. We prove that in addition to the direct population of the rhodamine triplet state (T1) formed through the intersystem crossing process with the assistance of a heavy Ir(III) metal center, the fine-tuned T1' state could act as a relay to provide an additional pathway for promoting the cascade energy transfer process that leads to enhanced ROS generation ability. Moreover, type I ROS can be effectively produced by introducing sulfur-containing thiophene units in C∧N ligands, providing a stronger M1 macrophage-activation efficiency under hypoxia to evoke in vivo antitumor immunity. Overall, our work provides a fundamental guideline for the molecular design and exploration of advanced transition-metal-based photosensitizers for biomedical applications.

Supramolecular Assembly Based on Calix(4)arene and Aggregation-Induced Emission Photosensitizer for Phototherapy of Drug-Resistant Bacteria and Skin Flap Transplantation

Photodynamic therapy as a burgeoning and non-invasive theranostic technique has drawn great attention in the field of antibacterial treatment but often encounters undesired phototoxicity of photosensitizers during systemic circulation. Herein, a supramolecular substitution strategy is proposed for phototherapy of drug-resistant bacteria and skin flap repair by using macrocyclic p-sulfonatocalix(4)arene (SC4A) as a host, and two cationic aggregation-induced emission luminogens (AIEgens), namely TPE-QAS and TPE-2QAS, bearing quaternary ammonium group(s) as guests. Through host-guest assembly, the obtained complex exhibits obvious blue fluorescence in the solution due to the restriction of free motion of AIEgens and drastically inhibits efficient type I ROS generation. Then, upon the addition of another guest 4,4'-benzidine dihydrochloride, TPE-QAS can be competitively replaced from the cavity of SC4A to restore its pristine ROS efficiency and photoactivity in aqueous solution. The dissociative TPE-QAS shows a high bacterial binding ability with an efficient treatment for methicillin-resistant Staphylococcus aureus (MRSA) in dark and light irradiation. Meanwhile, it also exhibits an improved survival rate for MRSA-infected skin flap transplantation and largely accelerates the healing process. Thus, such cascaded host-guest assembly is an ideal platform for phototheranostics research.

A biodegradable semiconducting polymer phototherapeutic agent for safe cancer phototherapy

Combined photodynamic therapy (PDT) and photothermal therapy (PTT) not only effectively reduce the hypoxic resistance to PDT, but also overcome the heat shock effect to PTT. However, the residual phototherapeutic agents still produce reactive oxygen species (ROS) to damage normal tissue under sunlight after treatment, which induces undesirable side effects to limit their biomedical application. Herein, a facile strategy is proposed to construct a biodegradable semiconducting polymer p-DTT, which is constructed by thieno[3,2-b]thiophene modified diketopyrrolopyrrole and (E)-1,2-bis(5-(trimethylstannyl)thiophen-2-yl)ethene moieties, to avoid the post-treatment side effects of phototherapy. Additionally, p-DTT exhibits strong photoacoustic (PA) for imaging, as well as good ROS production capacity and high photothermal conversion efficiency for synergistic PDT and PTT, which has been confirmed by both in vitro and in vivo results. After phototherapy, p-DTT could be gradually oxidized and degraded by endogenous ClO-, and subsequently lose ROS production and photothermal conversion capacities, which can guarantee the post-treatment safety, and address above key limitation of traditional phototherapy.

Enhancing Fractionated Cancer Therapy: A Triple-Anthracene Photosensitizer Unleashes Long-Persistent Photodynamic and Luminous Efficacy

Conventional photodynamic therapy (PDT) is often limited in treating solid tumors due to hypoxic conditions that impede the generation of reactive oxygen species (ROS), which are critical for therapeutic efficacy. To address this issue, a fractionated PDT protocol has been suggested, wherein light irradiation is administered in stages separated by dark intervals to permit oxygen recovery during these breaks. However, the current photosensitizers used in fractionated PDT are incapable of sustaining ROS production during the dark intervals, leading to suboptimal therapeutic outcomes (Table S1). To circumvent this drawback, we have synthesized a novel photosensitizer based on a triple-anthracene derivative that is designed for prolonged ROS generation, even after the cessation of light exposure. Our study reveals a unique photodynamic action of these derivatives, facilitating the direct and effective disruption of biomolecules and significantly improving the efficacy of fractionated PDT (Table S2). Moreover, the existing photosensitizers lack imaging capabilities for monitoring, which constraints the fine-tuning of irradiation parameters (Table S1). Our triple-anthracene derivative also serves as an afterglow imaging agent, emitting sustained luminescence postirradiation. This imaging function allows for the precise optimization of intervals between PDT sessions and aids in determining the timing for subsequent irradiation, thus enabling meticulous control over therapy parameters. Utilizing our novel triple-anthracene photosensitizer, we have formulated a fractionated PDT regimen that effectively eliminates orthotopic pancreatic tumors. This investigation highlights the promise of employing long-persistent photodynamic activity in advanced fractionated PDT approaches to overcome the current limitations of PDT in solid tumor treatment.

FRET-Based Host-Guest Supramolecular Probe for On-Site and Broad-Spectrum Detection of Pyrethroids in the Environment

The massive use of pyrethroid pesticides in agriculture has brought growing concerns about food safety due to their several harmful effects on human health, especially through the accumulation of the food chain. To date, most of the available analytical methods for pyrethroids still suffer from insufficient detection universality, complicated sample pretreatment, and detection processes, which severely limit their practical applications. Herein, a novel Förster resonance energy transfer (FRET)-assisted host-guest supramolecular nanoassembly is reported, for the first time, successfully realizing ratiometric fluorescent detection of pyrethroids in real samples through the indicator displacement assay (IDA) mechanism. This method is capable of detecting a broad spectrum of pyrethroids, including bifenthrin, cyfluthrin, cypermethrin, deltamethrin, etofenprox, fenvalerate, and permethrin, with ultrahigh detection sensitivity, great selectivity, high anti-interference ability, and, in particular, distinct emission color response from red to green. Such a large chromatic response makes this method available for fast and on-site detection of pyrethroids in real samples with the aid of several simple portable analytical apparatuses.

Promises of anionic calix[n]arenes in life science: State of the art in 2023

Because they hold together molecules by means of non-covalent interactions - relatively weak and thus, potentially reversible - the anionic calixarenes have become an interesting tool for efficiently binding a large range of ligands - from gases to large organic molecules. Being highly water soluble and conveniently biocompatible, they showed growing interest for many interdisciplinary fields, particularly in biology and medicine. Thanks to their intrinsic conical shape, they provide suitable platforms, from vesicles to bilayers. This is a valuable characteristic, as so they mimic the biologically functional architectures. The anionic calixarenes propose efficient alternatives for overcoming the limitations linked to drug delivery and bioavailability, as well as drug resistance along with limiting the undesirable side effects. Moreover, the dynamic non-covalent binding with the drugs enables predictable and on demand drug release, controlled by the stimuli present in the targeted environment. This particular feature instigated the use of these versatile, stimuli-responsive compounds for sensing biomarkers of diverse pathologies. The present review describes the recent achievements of the anionic calixarenes in the field of life science, from drug carriers to biomedical engineering, with a particular outlook on their applications for the diagnosis and treatment of different pathologies.

A ratiometric fluorescent probe for rapid and specific detection of hypochlorite

Hypochlorite (ClO- ), as a kind of essential reactive oxygen species, plays a crucial role in vitro and in vivo. Here, a ratiometric fluorescent probe (TPAM) was designed and constructed for sensing ClO- based on substituted triphenylamine and malononitrile, which exhibited obvious colour transfer from orange to colourless under daylight accompanied by noticeable fluorescence change from red to green in response to ClO- . TPAM could effectively monitor ClO- with the merits of fast response, excellent selectivity, high sensitivity and a low detection limit of 0.1014 μM. 1 H NMR, mass spectra and theoretical calculations proved that ClO- caused the oxidation of the carbon-carbon double bond in TPAM, resulting in compound 1 and marked changes in colour and fluorescence. In addition, TPAM was utilized for imaging ClO- in living cells successfully with good photostability and biocompatibility.

Spontaneous and Selective Macrocyclization in Nitroaldol Reaction Systems

Through a dynamic polymerization and self-sorting process, a range of lowellane macrocycles have been efficiently generated in nitroaldol systems composed of aromatic dialdehydes and aliphatic or aromatic dinitroalkanes. All identified macrocycles show a composition of two repeating units, resulting in tetra-β-nitroalcohols of different structures. The effects of the building block structure on the macrocyclization process have been demonstrated, and the influence from the solvent has been explored. In general, the formation of the lowellanes was amplified in response to phase-change effects, although solution-phase structures were, in some cases, favored.

Applications of supramolecular assemblies in drug delivery and photodynamic therapy

One of the world's serious health challenges is cancer. Anti-cancer agents delivered to normal cells and tissues pose several problems and challenges. In this connection, photodynamic therapy (PDT) is a minimally invasive therapeutic technique used for selectively destroying malignant cells while sparing the normal tissues. Development in photosensitisers (PSs) and light sources have to be made for PDT as a first option treatment for patients. In the pursuit of developing new attractive molecules and their formulations for PDT, researchers are working on developing such type of PSs that perform better than those being currently used. For the widespread clinical utilization of PDT, effective PSs are of particular importance. Host-guest interactions based on nanographene assemblies such as functionalized hexa-cata-hexabenzocoronenes, hexa-peri-hexabenzocoronenes and coronene have attracted increasing attention owing to less complicated synthetic steps and purification processes (gel permeation chromatography) during fabrication. Noncovalent interactions provide easy and facile approaches for building supramolecular PSs and enable them to have sensitive and controllable photoactivities, which are important for maximizing photodynamic effects and minimizing side effects. Various versatile supramolecular assemblies based on cyclodextrins, cucurbiturils, calixarenes, porphyrins and pillararenes have been designed in order to make PDT an effective therapeutic technique for curing cancer and tumours. The supramolecular assemblies of porphyrins display efficient electron transfer and fluorescence for use in bioimaging and PDT. The multifunctionalization of supramolecular assemblies is used for designing biomedically active PSs, which are helpful in PDT. It is anticipated that the development of these functionalized supramolecular assemblies will provide more fascinating advances in PDT and will dramatically expand the potential and possibilities in cancer treatments.

Supramolecular host-guest nanosystems for overcoming cancer drug resistance

Cancer drug resistance has become one of the main challenges for the failure of chemotherapy, greatly limiting the selection and use of anticancer drugs and dashing the hopes of cancer patients. The emergence of supramolecular host-guest nanosystems has brought the field of supramolecular chemistry into the nanoworld, providing a potential solution to this challenge. Compared with conventional chemotherapeutic platforms, supramolecular host-guest nanosystems can reverse cancer drug resistance by increasing drug uptake, reducing drug efflux, activating drugs, and inhibiting DNA repair. Herein, we summarize the research progress of supramolecular host-guest nanosystems for overcoming cancer drug resistance and discuss the future research direction in this field. It is hoped that this review will provide more positive references for overcoming cancer drug resistance and promoting the development of supramolecular host-guest nanosystems.

Synthetically Tunable Suprahybrid Nanoparticle Platform for the Efficacious Delivery of Therapeutics

The discovery of lipid-hybrid nanosystems has offered potential solutions to various drug delivery and theranostic challenges. However, in many instances, the commonly used lipids and other components in these systems often pose challenges related to their solubility, physicochemical properties, immune compatibility, and limited synthetic tunability. In this work, we introduce a synthetically tunable supramolecular scaffold with amphiphilic characteristics based on the calix[4]arene macrocyclic system. We designed and synthesized two novel calix[4]arene-polyethylene glycol (PEG) conjugates, termed Cal-P1 and Cal-P2, and these were characterized utilizing a wide range of spectroscopic and analytical methods. The rational design of Cal-P1 and Cal-P2 demonstrates their utility in forming stable blended nanospheres with sustained drug release characteristics. The synergistic blending of PLGA and the calixarene scaffold (Cal-P1 and Cal-P2) in constructing long-lasting and controlled-release nanoparticles (NPs), which are optimized for encapsulating Nile Red dye, and their successful internalization and retention in HeLa cancer cells are demonstrated through in vitro assays. The potential of these NPs as sustained therapeutic carriers is investigated in vivo, showing improved retention compared to free dye with negligible toxicity. The successful design and construction of Cal-P1 and Cal-P2 nanosystems represent a new paradigm for addressing drug loading challenges, opening up opportunities for the development of highly efficient, synthetically tunable alternative adjuvants for drug encapsulation and delivery.

Synthetic Receptors for Early Detection and Treatment of Cancer

Over recent decades, synthetic macrocyclic compounds have attracted interest from the scientific community due to their ability to selectively and reversibly form complexes with a huge variety of guest moieties. These molecules have been studied within a wide range of sensing and other fields. Within this review, we will give an overview of the most common synthetic macrocyclic compounds including cyclodextrins, calixarenes, calixresorcinarenes, pillarenes and cucurbiturils. These species all display the ability to form a wide range of complexes. This makes these compounds suitable in the field of cancer detection since they can bind to either cancer cell surfaces or indeed to marker compounds for a wide variety of cancers. The formation of such complexes allows sensitive and selective detection and quantification of such guests. Many of these compounds also show potential for the detection and encapsulation of environmental carcinogens. Furthermore, many anti-cancer drugs, although effective in in vitro tests, are not suitable for use directly for cancer treatment due to low solubility, inherent instability in in vivo environments or an inability to be adsorbed by or transported to the required sites for treatment. The reversible encapsulation of these species in a macrocyclic compound can greatly improve their solubility, stability and transport to required sites where they can be released for maximum therapeutic effect. Within this review, we intend to present the use of these species both in cancer sensing and treatment. The various macrocyclic compound families will be described, along with brief descriptions of their synthesis and properties, with an outline of their use in cancer detection and usage as therapeutic agents. Their use in the sensing of environmental carcinogens as well as their potential utilisation in the clean-up of some of these species will also be discussed.

A supramolecular nanoplatform for imaging-guided phototherapies via hypoxia tumour microenvironment remodeling

Photodynamic therapy (PDT) has emerged as an invasive and promising antitumour treatment, however, the hypoxia in deep tumour tissues and the poor water-solubility of photosensitizers as bottlenecks greatly hinder PDT efficiency. Herein, a tumour microenvironment (TME) activated supramolecular nanoplatform consisting of the pillar[5]arene-based amphiphilic polymer POPD, the phototherapeutic agent Cy7-CN, respiratory medication atovaquone (ATO) and chemotherapeutic drug pyridinyl camptothecin (CPT-Py) was constructed for imaging-guided hypoxia-ameliorated phototherapies. Owing to host-guest interaction, the photochemical and photophysical properties of cyanine were improved exceedingly due to the suppression of π-π stacking. Triggered by the acidic microenvironment in tumour sites, the supramolecular nanoplatform would dissociate and release CPT-Py and ATO which inhibits mitochondria-associated oxidative phosphorylation (OXPHOS) and encourages more oxygen to be used in enhanced PDT. In vitro and in vivo studies verified that the rational combination of ATO-enhanced PDT and PTT overcame the disadvantages of single phototherapy and formed mutual promotion, and simultaneously sensitized chemotherapeutic drugs, which resulted in high tumour inhibition. It is hoped that the supramolecular nanoplatform could shed light on the development of phototherapeutic agents.

Mitochondria-Targeting Multimodal Phototheranostics Based on Triphenylphosphonium Cation Modified Amphiphilic Pillararenes and A-D-A Fused-Ring Photosensitizers

Tumor-targeting phototheranostics has gradually developed as a powerful tool for the precise diagnosis and treatment of cancer. However, the designs of tumor-targeting phototheranostics agents with excellent multimodal phototherapy and fluorescence imaging (FLI) capability, as well as very few components, are still scarce and challenging for cancer treatment. Herein, a mitochondria-targeting multimodal phototheranostics system has been constructed by combining a designed amphiphilic pillararene WP5-2PEG-2TPP and the A-D-A fused-ring photosensitizer F8CA5. WP5-2PEG-2TPP is constructed by attaching the triphenylphosphonium cations to our previously reported dual PEG-functionalized amphiphilic pillararene, which can self-assemble into regular spherical nanocarriers with outstanding mitochondria targeting and water solubility. The A-D-A photosensitizer F8CA5 containing two methyl cyanoacetate group modified end groups displays superior photothermal conversion ability and dual type I/II photodynamic activity as well as strong NIR fluorescence emission. Through their strong union, multifunctional mitochondria-targeting phototheranostics agent F8CA5 NPs were obtained to be applied into FLI-guided synergistic photothermal and type I/II photodynamic therapy. As a result, F8CA5 NPs show good mitochondria-targeting and phototherapy effects in various tumor cells. Not only that, they can combat tumor hypoxia, which hinders the efficacy of photodynamic therapy. Therefore, this work provides a creative ideal for the construction of multifunctional tumor-targeting phototheranostic agents with excellent performance.

Pt nanozyme-bridged covalent organic framework-aptamer nanoplatform for tumor targeted self-strengthening photocatalytic therapy

Covalent organic frameworks (COFs) have emerged as a promising platform for nanomedicine, while developing multifunctional COF nanoplatforms remains challenging due to the lack of efficient strategies for COF modification. Herein, we propose a nanozyme bridging (NZB) strategy for COF functionalization. Platinum nanoparticles (Pt NPs) as catalase mimics were in situ grown on the surface of COF NPs without reducing their drug loading capacity (CP), and thiol-terminated aptamer was further densely decorated onto CP NPs via a stable Pt-S bond (CPA). Pt nanozyme engineering and aptamer functionalization rendered the nanoplatform with excellent photothermal conversion, tumor targeting, and catalase-like catalytic performances. Using clinical-approved photosensitizer indocyanine green (ICG) as a model drug, we fabricated a nanosystem (ICPA) for tumor-targeted self-strengthening therapy. ICPA can effectively accumulate into tumor tissue and relieve the hypoxia microenvironment by decomposing the overexpressed H₂O₂ and generating O₂. Under monowavelength NIR light irradiation, the catalase-like catalytic and singlet oxygen generation activities of ICPA can be significantly strengthened, leading to admirable photocatalytic treatment effects against malignant cells as well as tumor-bearing mice in a self-strengthening manner.

Designing supramolecular self-assembly nanomaterials as stimuli-responsive drug delivery platforms for cancer therapy

Stimuli-responsive nanomaterials have attracted substantial interest in cancer therapy, as they hold promise to deliver anticancer agents to tumor sites in a precise and on-demand manner. Interestingly, supramolecular chemistry is a burgeoning discipline that entails the reversible bonding between components at the molecular and nanoscale levels, and the recent advances in this area offer the possibility to design nanotherapeutics with improved controllability and functionality for cancer therapy. Herein, we provide a comprehensive summary of typical non-covalent interaction modes, which primarily include hydrophobic interaction, hydrogel bonding, host-guest interaction, π-π stacking, and electrostatic interaction. Special emphasis is placed on the implications of these interaction modes to design novel stimuli-responsive drug delivery principles and concepts, aiming to enhance the spatial, temporal, and dosage precision of drug delivery to cancer cells. Finally, future perspectives are discussed to highlight current challenges and future opportunities in self-assembly-based stimuli-responsive drug delivery nanotechnologies for cancer therapy.

Fluorophore-based host-guest assembly complexes for imaging and therapy

Recently, supramolecular chemistry with its unique properties has received considerable attention in many fields. Supramolecular fluorescent systems constructed on the basis of macrocyclic hosts are not only effective in overcoming the limitations of imaging and diagnostic reagents, but also in enhancing their performances. This paper summarizes the recent advances in supramolecular fluorescent systems based on host-guest interactions and their application in bioimaging and therapy as well as the challenges and prospects in developing novel supramolecular fluorescent systems.

Platelet membrane camouflaged AIEgen-mediated photodynamic therapy improves the effectiveness of anti-PD-L1 immunotherapy in large-burden tumors

Although immunotherapy has achieved recent clinical success in antitumor therapy, it is less effective for solid tumors with large burdens. To overcome this challenge, herein, we report a new strategy based on platelet membrane-camouflaged aggregation-induced emission (AIE) luminogen (Plt-M@P) combined with the anti-programmed death ligand 1 (anti-PD-L1) for tumoral photodynamic-immunotherapy. Plt-M@P is prepared by using poly lactic-co-glycolic acid (PLGA)/PF3-PPh3 complex as a nanocore, and then by co-extrusion with platelet membranes. PF3-PPh3 is an AIE-active conjugated polyelectrolyte with photosensitizing capability for photodynamic therapy (PDT). Plt-M@P exhibits superior tumor targeting capacity in vivo. When applied in small tumor-bearing (~40 mm3) mice, Plt-M@P-mediated PDT significantly inhibits tumor growth. In tumor models with large burdens (~200 mm3), using Plt-M@P-mediated PDT or anti-PD-L1 alone is less effective, but the combination of both is effective in inhibiting tumor growth. Importantly, this combination therapy has good biocompatibility, as demonstrated by the absence of damage to the major organs, especially the reproductive system. In conclusion, we show that Plt-M@P-mediated PDT can improve anti-PD-L1 immunotherapy by enhancing antitumor effects, providing a promising strategy for the treatment of tumors with large burdens.

Engineered Metallacycle-Based Supramolecular Photosensitizers for Effective Photodynamic Therapy

Although metallacycle-based supramolecular photosensitizers (PSs) have attracted increasing attention in biomedicine, their clinical translation is still hindered by their inherent dark toxicity. Herein, we report what to our knowledge is the first example of a molecular engineering approach to building blocks of metallacycles for constructing a series of supramolecular PSs (RuA-RuD), with the aim of simultaneously reducing dark toxicity and enhancing phototoxicity, and consequently obtaining high phototoxicity indexes (PI). Detailed in vitro investigations demonstrate that RuA-RuD display high cancer cellular uptake and remarkable antitumor activity even under hypoxic conditions. Notably, RuD exhibited no dark toxicity and displayed the highest PI value (≈406). Theoretical calculations verified that RuD has the largest steric hindrance and the lowest singlet-triplet energy gap (ΔE_ST , 0.61 eV). Further in vivo studies confirmed that RuD allows safe and effective phototherapy against A549 tumors.

Halogen Bond-Driven Aggregation-Induced Emission Skeleton: N-(3-(Phenylamino)allylidene) Aniline Hydrochloride

Aggregation-induced emission (AIE) is a unique photophysical process, and its emergence brings a revolutionary change in luminescence. However, AIE-based research has been limited to a few classical molecular skeletons, which is unfavorable for in-depth studies of the photophysical characteristics of AIE and the full exploitation of their potential values. There is an urgent need to develop new skeletons to rise to the challenges of an insufficient number of AIE core structures and difficult modification. Here, we report a novel dumbbell AIE skeleton, in which two phenyls are connected through (E)-3-iminoprop-1-en-1-amine. This skeleton shows extremely strong solid-state emission with an absolute quantum yield up to 69.5%, a large Stokes shift, and typical AIE characteristics, which well resolves the challenge of difficult modification and low luminous efficiency of the traditional AIE skeletons. One-step reaction, high yield, and diversified modification endow the skeleton with great scalability from simple to complicated, or from symmetrical to asymmetrical structures, which establishes the applicability of the skeleton in various scenarios. These molecules self-assemble into highly ordered layer-, rod-, petal-, hollow pipe-, or helix-like nanostructures, which contribute to strong AIE emission. Crystallographic data reveal the highly ordered layer structures of the aggregates with different substituents, and a novel halogen bond-driven self-assembly mechanism that restricts intramolecular motion is clearly discovered. Taking advantage of these merits, a full-band emission system from green to red is successfully established, which displays great potential in the construction of light-emitting films and advanced light-emitting diodes. The discovery of this AIE skeleton may motivate a huge potential application value in luminescent materials and lead to hitherto impossible technological innovations.

Recent Advances in Supramolecular-Macrocycle-Based Nanomaterials in Cancer Treatment

Cancer is a severe threat to human life. Recently, various therapeutic strategies, such as chemotherapy, photodynamic therapy, and combination therapy have been extensively applied in cancer treatment. However, the clinical benefits of these therapeutics still need improvement. In recent years, supramolecular chemistry based on host-guest interactions has attracted increasing attention in biomedical applications to address these issues. In this review, we present the properties of the major macrocyclic molecules and the stimulus-response strategies used for the controlled release of therapeutic agents. Finally, the applications of supramolecular-macrocycle-based nanomaterials in cancer therapy are reviewed, and the existing challenges and prospects are discussed.

Hypoxia-Responsive Photosensitizer Targeting Dual Organelles for Photodynamic Therapy of Tumors

Developing safe and precise image-guided photodynamic therapy is a challenge. In this study, the hypoxic properties of solid tumors are exploited to construct a hypoxia-responsive photosensitizer, TPA-Azo. Introducing the azo group into the photosensitizer TPA-BN with aggregation-induced emission quenches its fluorescence. When the nonfluorescent TPA-Azo enters hypoxic tumors, it is reduced by the overexpressed azoreductase to generate a fluorescent photosensitizer TPA-BN with an amino group that exhibits fluorescence-activatable image-guided photodynamic therapy with dual-organelle (lipid droplets and lysosomes) targeting. This design strategy provides a basis for the development of fluorescence-activatable photosensitizers.

Supramolecular photosensitizers using extended macrocyclic hosts for photodynamic therapy with distinct cellular delivery

Two hydrophilic macrocycles can strongly bind hypocrellin B. The resulting supramolecular photosensitizers show excellent photodynamic efficiency with different cellular delivery.

Biomimetic dual-responsive bioengineered nanotheranostics for intracellular cascade-synthesizing chemo-drugs and efficient oncotherapy

Intracellular-synthesized chemo-drugs based on the inherent characteristics of the tumor microenvironment (TME) have been extensively applied in oncotherapy. However, combining other therapeutic strategies to convert nontoxic small molecules into toxic small-molecule chemo-drugs in the TME is still a huge challenge. To address this issue, herein we have developed a biomimetic dual-responsive bioengineered nanotheranostics system via the supramolecular co-assembly of the nontoxic small-molecule 1,5-dihydroxynaphthalene (DHN) and small-molecule photosensitizer indocyanine green (ICG) followed by surface cloaking through red blood cell membranes (RBCs) for intracellular cascade-synthesizing chemo-drugs and efficient oncotherapy. Such nanotheranostics with a suitable diameter, core-shell structure, ultrahigh dual-drug payload rate, and excellent stability can efficiently accumulate in tumor regions and then internalize into tumor cells. Under the dual stimulations of near-infrared laser irradiation and acidic lysosomes, the nanotheranostics system exhibited exceptional instability under heat-primed membrane rupture and pH decrease, thereby achieving rapid disassembly and on-demand drug release. Furthermore, the released ICG can efficiently convert ³O₂ into ¹O₂. After that, the generated ¹O₂ can efficiently oxidize the released nontoxic DHN into the highly toxic chemo-drug juglone, thereby realizing intracellular cascade-synthesizing chemo-drugs and synergistic photodynamic-chemotherapy while reducing detrimental side effects on normal cells or tissues. Overall, it is envisioned that RBC-cloaked nanotheranostics with intracellular cascade-synthesizing chemo-drugs can provide a promising strategy for intracellular chemo-drug synthesis-based oncotherapy.

Mechanical Force-Induced Blue-Shifted and Enhanced Emission for AIEgens

Mechanochromic (MC) luminescence of organic molecules has been emerging as a promising smart material for optical recording and memory devices. At the same time, pressure-induced blue-shifted and enhanced luminescence are rarely reported now. Herein, a series of cyanostilbene-based AIEgens with different substituents were synthesized to evaluate the influence of morphology transformation and push-pull electronic effect on the MC luminescence. Among these luminophores, compound 1 with one cyano group and diethylamino group was more susceptible to mechanical stimuli and obtained blue-shifted and enhanced fluorescence in response to anisotropic grinding. Powder X-ray diffraction patterns indicated that the MC behaviors were ascribed to the solid-state morphology transition from crystal-to-crystal. Analysis of crystal structures revealed that loose molecular packing is a key factor for high high-contrast MC luminescence. The smart molecular design, together with the excellent performance, verified that luminophores with twisted structures are ideal candidates for MC luminogens.

Association Complexes of Calix[6]arenes with Amino Acids Explained by Energy-Partitioning Methods

Intermolecular complexes with calixarenes are intriguing because of multiple possibilities of noncovalent binding for both polar and nonpolar molecules, including docking in the calixarene cavity. In this contribution calix[6]arenes interacting with amino acids are studied with an additional aim to show that tools such as symmetry-adapted perturbation theory (SAPT), functional-group SAPT (F-SAPT), and systematic molecular fragmentation (SMF) methods may provide explanations for different numbers of noncovalent bonds and of their varying strength for various calixarene conformers and guest molecules. The partitioning of the interaction energy provides an easy way to identify hydrogen bonds, including those with unconventional hydrogen acceptors, as well as other noncovalent bonds, and to find repulsive destabilizing interactions between functional groups. Various other features can be explained by energy partitioning, such as the red shift of an IR stretching frequency for some hydroxy groups, which arises from their attraction to the phenyl ring of calixarene. Pairs of hydrogen bonds and other noncovalent bonds of similar magnitude found by F-SAPT explain an increase in the stability of both inclusion and outer complexes.

Aggregation-Induced Emission Luminogens for Enhanced Photodynamic Therapy: From Organelle Targeting to Tumor Targeting

Photodynamic therapy (PDT) has attracted much attention in the field of anticancer treatment. However, PDT has to face challenges, such as aggregation caused by quenching of reactive oxygen species (ROS), and short 1O2 lifetime, which lead to unsatisfactory therapeutic effect. Aggregation-induced emission luminogen (AIEgens)-based photosensitizers (PSs) showed enhanced ROS generation upon aggregation, which showed great potential for hypoxic tumor treatment with enhanced PDT effect. In this review, we summarized the design strategies and applications of AIEgen-based PSs with improved PDT efficacy since 2019. Firstly, we introduce the research background and some basic knowledge in the related field. Secondly, the recent approaches of AIEgen-based PSs for enhanced PDT are summarized in two categories: (1) organelle-targeting PSs that could cause direct damage to organelles to enhance PDT effects, and (2) PSs with tumor-targeting abilities to selectively suppress tumor growth and reduce side effects. Finally, current challenges and future opportunities are discussed. We hope this review can offer new insights and inspirations for the development of AIEgen-based PSs for better PDT effect.

Folic Acid-Modified Cyclodextrin Multivalent Supramolecular Assembly for Photodynamic Therapy

The construction of supramolecular multivalent assemblies with unique photoluminescence behaviors and biological functions has become a research hot spot recently in the biomaterial field. Herein, we report an adaptive supramolecular assembly via a multivalent co-assembly strategy prepared in two stages by using an adamantane-connected pyrenyl pyridinium derivative (APA2), sulfonated aluminum phthalocyanine (PcS), and folic acid-modified β-cyclodextrin (FA-CD) for efficient dual-organelle targeted photodynamic cancer cell ablation. Benefiting from π-π and electrostatic interactions, APA2 and PcS could first assemble into non-fluorescent irregular nanoaggregates because of the heterodimer aggregation-induced quenching and then secondarily assemble with FA-CD to afford targeted spherical nanoparticles (NPs) with an average diameter of around 50 nm, which could be specifically taken up by HeLa cancer cells through endocytosis in comparison with 293T normal cells. Intriguingly, such multivalent NPs could adaptively disaggregate in an intracellular physiological environment of cancer cells and further respectively and selectively accumulate in mitochondria and lysosomes, which not only displayed near-infrared two-organelle localization in situ but also aroused efficient singlet oxygen generation under light irradiation to effectively eliminate cancer cells up to 99%. This supramolecular multivalent assembly with an adaptive feature in a specific cancer cell environment provides a feasible strategy for precise organelle-targeted imaging and an efficiently synergetic photodynamic effect in situ for cancer cell ablation.

A Bacteria-Responsive Porphyrin for Adaptable Photodynamic/Photothermal Therapy

We report a cationic porphyrin 5,10,15,20-tetrakis-(4-N-methylpyridyl)-porphyrin (TMPyP) that can respond to specific bacteria, followed by adaptable photodynamic/photothermal therapy processes. TMPyP could be reduced to phlorin by facultative anaerobes with a strong reducing ability such as E. coli and S. typhimurium in hypoxic environments, possessing strong NIR absorption and remarkable photothermal conversion capacity, thus demonstrating excellent antimicrobial activity (>99 %) by photothermal therapy. While in an aerobic environment with aerobic bacteria, TMPyP functioned as a typical photosensitizer that killed bacteria effectively (>99.9 %) by photodynamic therapy. By forming a host-guest complex with cucurbit[7]uril, the biocompatibility of TMPyP significantly improved. This kind of bacteria-responsive porphyrin shows specificity and adaptivity in antimicrobial treatment and holds potential in non-invasive treatments of bacterial infections.

Cyclodextrin-Activated Porphyrin Photosensitization for Boosting Self-Cleavable Drug Release

Supramolecular prodrugs that combine the merits of stimuli-responsiveness and targeting ability in a controllable manner have shown appealing prospects in disease diagnostics and therapeutics. Herein, we report that a new theranostic agent with the host-guest-binding-activated photosensitization has been fabricated by a binary supramolecular assembly consisting of the permethyl-β-cyclodextrin-grafted hyaluronic acid and a combretastatin A-4-appended porphyrin derivative. Illuminated by a red-light source, the production efficiency of singlet oxygen (¹O₂) pronouncedly increases by ∼60-fold once the porphyrin core is encapsulated by cyclodextrins. Consequently, the cell-selective fluorescence emission is dramatically enhanced, the microtubule-targeted drug is rapidly and completely released, and the ¹O₂-involved combinational treatment is simultaneously achieved both in vitro and in vivo. To be envisaged, this complexation-boosted light-activatable photosensitizing prodrug delivery system with improved photophysical performance and remarkable phototheranostic outcomes will make a significant contribution to the creation of more advanced stimulus-based biomaterials.

Phototherapy Using a Fluoroquinolone Antibiotic Drug to Suppress Tumor Migration and Proliferation and to Enhance Apoptosis

In this work, a fluoroquinolone antibiotic drug (sparfloxacin (SP)) was selected as a chemotherapy drug and photosensitizer for combined therapy. A facile chemical process was developed to incorporate SP and upconversion nanoparticles (UCNPs) into the thermally sensitive amphiphilic polymer polyethylene glycol-poly(2-hexoxy-2-oxo-1,3,2-dioxaphospholane). In vitro and in vivo experiments showed that 60% of the SP molecules can be released from the micelles of thermal-sensitive polymers using a 1 W cm^-2 980 nm laser, and this successfully inhibits cell migration and metastasis by inhibiting type II topoisomerases in nuclei. Additionally, intracellular metal ions were chelated by SP to induce cancer cell apoptosis by decreasing the activity of superoxide dismutase and catalase. In particular, the fluoroquinolone molecules produced singlet oxygen (¹O₂) to kill cancer cells, and this was triggered by UCNPs when irradiation was performed with a 980 nm laser. Overall, SP retained a weak chemotherapeutic effect, achieved enhanced photosensitizer-like effects, and was able to repurpose old drugs to elevate the therapeutic efficacy against cancer, increase the specificity for suppressing tumor migration and proliferation, and enhance apoptosis.

Induced Near-Infrared Emission and Controlled Photooxidation based on Sulfonated Crown Ether in Water

Regulation of physio-chemical properties and reaction activities via noncovalent methodology has become one of increasingly significant topics in supramolecular chemistry and showed inventive applications in miscellaneous fields. Herein, we demonstrate that sulfonated crown ether can form very stable host-guest complexes with a series of push-pull-type photosensitizers, eventually leading to the dramatic fluorescence enhancement in visible and near-infrared regions. Meanwhile, severe suppression in singlet oxygen (¹ O₂ ) production is found, mainly due to the higher energy barriers between the excited single and triple states upon host-guest complexation. Moreover, such complexation-induced tuneable ¹ O₂ generation systems has been utilized in adjusting the photochemical oxidation reactions of polycyclic aromatic hydrocarbons (anthracene) and sulfides ((methylthio)benzene) in water. This supramolecularly controlled photooxidation based on the selective molecular binding of crown ether with photosensitizers may provide a feasible and applicable strategy for monitoring and modulating many photocatalysis processes in aqueous phase.