The development of light-responsive, organic dye based, supramolecular nanosystems for enhanced anticancer therapy

Phenazinium- and Malachite Green-Based Pd(II) Cages: Chiroptical Discrimination of Nucleoside Triphosphates

Organic chromophores have been successfully implemented into supramolecular systems to bestow them with distinct photophysical properties for various applications, ranging from solar energy conversion, photochemical reactions or as receptors for guest molecules with optical readout. We had previously introduced first members of the large family of coal-tar dyes (methylene blue, crystal violet and rhodamine) as integral components of coordination cages. Here, we add two new chromophores, malachite green (MGP) and a purple phenazinium dye (PHP), serving as backbones of bis-monodentate banana-shaped ligands with pyridine donors. We show the formation of corresponding green and purple coloured Pd2L4 coordination cages and investigate their interaction with chiral guest molecules via UV-Vis and CD spectroscopy. The PHP cage can be used to recognize nucleoside triphosphates, based on chirality transfer from the guests to the structurally flexible helicate. In combination with the already known methylene blue cage MBP we could further differentiate between all four canonical NTPs through characteristic changes in the observed CD signatures.

GSH-responsive bithiophene Aza-BODIPY@HMON nanoplatform for achieving triple-synergistic photoimmunotherapy

Photoimmunotherapy represents an innovative approach to enhancing the efficiency of immunotherapy in cancer treatment. This approach involves the fusion of immunotherapy and phototherapy (encompassing techniques like photodynamic therapy (PDT) and photothermal therapy (PTT)). Boron-dipyrromethene (BODIPY) has the potential to trigger immunotherapy owing to its excellent PD and PT efficiency. However, the improvements in water solubility, bioavailability, PD/PT combined efficiency, and tumor tissue targeting of BODIPY require introduction of suitable carriers for potential practical application. Herein, a disulfide bond-based hollow mesoporous organosilica (HMON) with excellent biocompatibility and GSH-responsive degradation properties was used as a carrier to load a bithiophene Aza-BODIPY dye (B5), constructing a sample chemotherapy reagent-free B5@HMON nanoplatform achieving triple-synergistic photoimmunotherapy. HMON, involving disulfide bond, is utilized to improve water solubility, tumor tissue targeting, and PD efficiency by depleting GSH and enhancing host-guest interaction between B5 and HMO. The study reveals that HMON's large specific surface area and porous properties significantly enhance the light collection and oxygen adsorption capacity. The HMON's rich mesoporous structure and internal cavity achieved a loading rate of B5 at 11 %. It was found that the triple-synergistic nanoplatform triggered a stronger anti-tumor immune response, including tumor invasion, cytokine production, calreticulin translocation, and dendritic cell maturation, eliciting specific tumor-specific immunological responses in vivo and in vitro. The BALB/c mouse model with 4T1 tumors was used to assess tumor suppression efficiency in vivo, showing that almost all tumors in the B5@HMON group disappeared after 14 days. Such a simple chemotherapy reagent-free B5@HMON nanoplatform achieved triple-synergistic photoimmunotherapy.

(Nano)biotechnological approaches in the treatment of cervical cancer: integration of engineering and biology

Cervical cancer is one of the most malignant gynaecological tumors characterised with the aggressive behaviour of the tumor cells. In spite of the development of different strategies for the treatment of cervical cancer, the tumor cells have developed resistance to conventional therapeutics. On the other hand, nanoparticles have been recently applied for the treatment of human cancers through delivery of drugs and facilitate tumor suppression. The stimuli-sensitive nanostructures can improve the release of therapeutics at the tumor site. In the present review, the nanostructures for the treatment of cervical cancer are discussed. Nanostructures can deliver both chemotherapy drugs and natural compounds to increase anti-cancer activity and prevent drug resistance in cervical tumor. Moreover, the genetic tools such as siRNA can be delivered by nanoparticles to enhance their accumulation at tumor site. In order to enhance selectivity, the stimuli-responsive nanoparticles such as pH- and redox-responsive nanocarriers have been developed to suppress cervical tumor. Moreover, nanoparticles can induce photo-thermal and photodynamic therapy to accelerate cell death in cervical tumor. In addition, nanobiotechnology demonstrates tremendous potential in the treatment of cervical cancer, especially in the context of tumor immunotherapy. Overall, metal-, carbon-, lipid- and polymer-based nanostructures have been utilized in cervical cancer therapy. Finally, hydrogels have been developed as novel kinds of carriers to encapsulate therapeutics and improve anti-cancer activity.

Phototriggered structures: Latest advances in biomedical applications

Non-invasive control of the drug molecules accessibility is a key issue in improving diagnostic and therapeutic procedures. Some studies have explored the spatiotemporal control by light as a peripheral stimulus. Phototriggered drug delivery systems (PTDDSs) have received interest in the past decade among biological researchers due to their capability the control drug release. To this end, a wide range of phototrigger molecular structures participated in the DDSs to serve additional efficiency and a high-conversion release of active fragments under light irradiation. Up to now, several categories of PTDDSs have been extended to upgrade the performance of controlled delivery of therapeutic agents based on well-known phototrigger molecular structures like o-nitrobenzyl, coumarinyl, anthracenyl, quinolinyl, o-hydroxycinnamate and hydroxyphenacyl, where either of one endows an exclusive feature and distinct mechanistic approach. This review conveys the design, photochemical properties and essential mechanism of the most important phototriggered structures for the release of single and dual (similar or different) active molecules that have the ability to quickly reason of the large variety of dynamic biological phenomena for biomedical applications like photo-regulated drug release, synergistic outcomes, real-time monitoring, and biocompatibility potential.

A comparison on the biochemical activities of Fluorescein disodium, Rose Bengal and Rhodamine 101 in the light of DNA binding, antimicrobial and cytotoxic study

Biochemical activities of Fluorescein, Rose Bengal and Rhodamine 101 were studied by DNA binding, antibacterial and cytotoxic studies. DNA binding studies were done using spectroscopic, thermodynamic and molecular modeling techniques. Antibacterial activities were investigated against a gram-negative bacteria Escherichia coli and a gram-positive bacteria Staphylococcus aureus. Cytotoxic activities were studied against Wi-38 cell line. We observed these dyes bound to minor groove of DNA and structural diversity of dyes affect the phenomenon. No significant antibacterial and cytotoxic activities of these dyes were found in our observations.

Rose bengal-modified gold nanorods for PTT/PDT antibacterial synergistic therapy

In this study, Rose Bengal (RB) was loaded onto mesoporous silica coated gold nanorods (AuNR@SiO₂-NH₂) to form a novel multifunctional platform for antimicrobial therapy (AuNR@SiO₂-NH₂-RB). The platform combines the photothermal functions of AuNR and the photodynamic functions of RB to effectively inactivate bacteria under irradiation. Moreover, AuNR@SiO₂-NH₂-RB showed negligible cytotoxicity and good blood compatibility. Therefore, this work has potential significance for the development of new antibacterial agents.

Advances in the Structural Strategies of the Self-Assembly of Photoresponsive Supramolecular Systems

Photosensitive supramolecular systems have garnered attention due to their potential to catalyze highly specific tasks through structural changes triggered by a light stimulus. The tunability of their chemical structure and charge transfer properties provides opportunities for designing and developing smart materials for multidisciplinary applications. This review focuses on the approaches reported in the literature for tailoring properties of the photosensitive supramolecular systems, including MOFs, MOPs, and HOFs. We discuss relevant aspects regarding their chemical structure, action mechanisms, design principles, applications, and future perspectives.

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.

A Facile, Protein-Derived Supramolecular Theranostic Strategy for Multimodal-Imaging-Guided Photodynamic and Photothermal Immunotherapy In Vivo

Theranostic systems that permit both diagnosis and treatment in vivo are highly appealing means by which to meet the demands of precision medicine. However, most such systems remain subject to issues related to complex molecular design and synthesis, potential toxicity, and possible photoactivity changes. Herein, a novel supramolecular theranostic strategy involving biomarker protein activation (BPA) and a host-guest strategy is proposed. To exemplify BPA, a facile "one-for-all" nanotheranostic agent for both albumin detection and cancer treatment is demonstrated, which utilizes a nanoparticulate heavy-atom-free BODIPY dye derivative (B4 NPs). The fluorescence and photoactivity of BODIPY dyes are completely suppressed by aggregation-induced self-quenching in the nanoparticulate state. However, a Balb/c nude mouse model is used to confirm that following the disassembly of injected B4 NPs, BODIPY specifically binds albumin in vivo, accompanied by significantly enhanced biocompatibility and photothermal conversion efficiency. More importantly, this supramolecular host-guest BPA strategy enables the resultant nanoplatform to act as a facile and efficient strategy for photodynamic and photothermal immunotherapy.

Near-infrared emissive polymer-coated IR-820 nanoparticles assisted photothermal therapy for cervical cancer cells

Photothermal therapy (PTT) has attracted wide attention due to its noninvasiveness and its thermal ablation ability. As photothermal agents are crucial factor in PTT, those with the characteristics of biocompatibility, non-toxicity and high photothermal stability have attracted great interest. In this work, new indocyanine green (IR-820) was utilized as a photothermal agent and near-infrared (NIR) fluorescence imaging nanoprobe. To improve the biocompatibility, poly(styrene-co-maleic anhydride) (PSMA) was utilized to encapsulate the IR-820 molecules to form novel IR-820@PSMA nanoparticles (NPs). Then, the optical and thermal properties of IR-820@PSMA NPs were studied in detail. The IR-820@PSMA NPs showed excellent photothermal stability and biocompatibility. The cellular uptaking ability of the IR-820@PSMA NPs was further confirmed in HeLa cells by the NIR fluorescent confocal microscopic imaging technique. The IR-820@PSMA NPs assisted PTT of living HeLa cells was conducted under 793 nm laser excitation, and a high PTT efficiency of 73.3% was obtained.

Bi19S27I3 nanorods: a new candidate for photothermal therapy in the first and second biological near-infrared windows

Near-infrared (NIR) light-induced photothermal cancer therapy using nanomaterials as photothermal agents has attracted considerable research interest over the past few years. As the key factor in photothermal therapy systems, a variety of photothermal agents have been developed. However, the exploration of novel photothermal therapy nanoplatforms with high NIR absorption remains a significant challenge, especially those working in both NIR-I and NIR-II windows. In this work, Bi19S27I3 nanorods with remarkably high absorption covering the whole visible light to the entire NIR-I and NIR-II regions have been successfully prepared through a facile solvothermal approach. The as-synthesized Bi19S27I3 nanorods have a high photothermal conversion efficiency of 42.7% at 808 nm (NIR-I) and 41.5% at 1064 nm (NIR-II), making them a promising candidate for photothermal therapy. In vitro cell viability assay reveals that the Bi19S27I3 sample has good biocompatibility and exhibits significant cell-killing effect under NIR irradiation. In vivo anti-tumor experiments demonstrate that the tumor growth can be effectively inhibited by fatal hyperthermia ablation mediated by Bi19S27I3 nanorods under the irradiation of an 808 nm or 1064 nm laser. Therefore, this study should be primarily beneficial for the development of new materials for NIR photothermal therapy applications.

Coal-Tar Dye-based Coordination Cages and Helicates

A strategy to implement four members of the classic coal-tar dye family, Michler's ketone, methylene blue, rhodamine B, and crystal violet, into [Pd2 L4 ] self-assemblies is introduced. Chromophores were incorporated into bis-monodentate ligands using piperazine linkers that allow to retain the auxochromic dialkyl amine functionalities required for intense colors deep in the visible spectrum. Upon palladium coordination, ligands with pyridine donors form lantern-shaped dinuclear cages while quinoline donors lead to strongly twisted [Pd2 L4 ] helicates in solution. In one case, single crystal X-ray diffraction revealed rearrangement to a [Pd3 L6 ] ring structure in the solid state. For nine examined derivatives, showing colors from yellow to deep violet, CD spectroscopy discloses different degrees of chiral induction by an enantiomerically pure guest. Ion mobility mass spectrometry allows to distinguish two binding modes. Self-assemblies based on this new ligand class promise application in chiroptical recognition, photo-redox catalysis and optical materials.

Evidence for Dual Site Binding of Nile Blue A toward DNA: Spectroscopic, Thermodynamic, and Molecular Modeling Studies

Binding of Nile Blue (NB) with calf thymus DNA has been studied using molecular modeling, spectroscopic, and thermodynamic techniques. Our study revealed that NB binds to the DNA helix by two types of modes (groove binding and intercalation) simultaneously. The thermodynamic study showed that the overall binding free energy is a combination of several negative and positive free energy changes. The binding was favored by negative enthalpy and positive entropy changes (due to the release of water from the DNA helix). The docking study validated all experimental evidence and showed that NB binds to a DNA minor groove at low concentrations and switches to intercalation mode at higher concentrations.

Protein-Activatable Diarylethene Monomer as a Smart Trigger of Noninvasive Control Over Reversible Generation of Singlet Oxygen: A Facile, Switchable, Theranostic Strategy for Photodynamic-Immunotherapy

The development of activatable photosensitizers to allow for the reversible control of singlet oxygen (¹O₂) production for photodynamic therapy (PDT) faces great challenges. Fortunately, the flourishing field of supramolecular biotechnology provides more effective strategies for activatable PDT systems. Here, we developed a new reversible PDT on a switch that controls the ¹O₂ generation of self-assembled albumin nanotheranostics in vitro and in vivo. A new molecular design principle of aggregation-induced self-quenching photochromism and albumin on-photoswitching was demonstrated using a new asymmetric, synthetic diarylethene moiety DIA. The photosensitizer porphyrin and DIA were incorporated as building blocks in a glutaraldehyde-induced covalent albumin cross-linking nanoplatform, HSA-DIA-porphyrin nanoparticles (NPs). More importantly, the excellent photoswitching property of DIA enables the resultant nanoplatform to act as a facile, switchable strategy for photodynamic-immunotherapy.

Synthesis of fluorescent nanoprobe with simultaneous response to intracellular pH and Zn2+ for tumor cell distinguishment

A novel dual-functional nanoprobe was designed and synthesized by facile assembly of quinoline derivative (PEIQ) and meso-tetra (4-carboxyphenyl) porphine (TCPP) via electrostatic interaction for simultaneous sensing of fluorescence of Zn²⁺ and pH. Under the single-wavelength excitation at 400 nm, this nanoprobe not only exhibits "OFF-ON" green fluorescence at 512 nm by specific PEIQ-Zn²⁺ chelation, but also presents red fluorescence enhancement at 654 nm by H⁺-triggered TCPP release. The nanoprobe demonstrated excellent sensing performance with a good linear range (Zn²⁺, 1-40 μM; pH, 5.0-8.0), low detection limit (Zn²⁺, 0.88 μM), and simultaneous response towards Zn²⁺ and pH in pure aqueous solution within 2 min. More importantly, this dual-functional nanoprobe demonstrates the capability of discerning cancerous cells from normal cells, as evidenced by the fact that cancerous HepG2 cells in tumor microenvironment exhibit substantially higher red fluorescence and significantly lower green fluorescence than normal HL-7702 cells. The simultaneous, real-time fluorescence imaging of multiple analytes in a living system could be significant for cell analysis and tracking, cancer diagnosis, and even fluorescence-guided surgery of tumors.

Glutathione-Responsive Multifunctional "Trojan Horse" Nanogel as a Nanotheranostic for Combined Chemotherapy and Photodynamic Anticancer Therapy

It remains a great challenge to design a multifunctional and robust nanoplatform for stimuli-responsive drug delivery toward a lesion, which tactfully integrates multiple molecules with therapeutic and diagnostic characteristics. Herein, we reported a facile and ingenious cross-linked nanogel (DSA) based on the chemical cross-link of drugs as a straightforward strategy to overcome the instability of the assembly. In DSA, doxorubicin (DOX) and 5-aminolevulinic acid (ALA) were cross-linked with a disulfide linker for realizing synergistic anticancer therapy. The stability of DSA was adjusted via balancing the hydrophobic/hydrophilic property with hydrophilic NH2-PEG1k. After regulating the coordination of the DOX part and ALA moiety, the drug-loaded nanogel exhibited superior chemotherapeutic efficacies. Additionally, the DSA could selectively biosynthesize fluorescent protoporphyrin IX (PpIX) in tumor cells, which could be applied for a real-time imaging probe of accurate cancer diagnosis. Besides, the in situ synthesized PpIX in mitochondria could serve as a photosensitizer to convert oxygen into toxic reactive oxygen species under a near infrared ray at 660 nm irradiation, leading to an excellent tumor-killing efficacy. This work proposed a unique strategy for designing a series of prodrug nanogels as a universal drug delivery platform for realizing precise disease therapy and diagnostics.

Assembly strategies of organic-based imaging agents for fluorescence and photoacoustic bioimaging applications

The results of numerous studies have led to the development of supramolecular (assembled) organic substances for use in biomedical imaging as part of comprehensive approaches to the diagnosis of diseases. This review summarizes recent advances that have been made in the design and fabrication of assembled organic dyes for fluorescence and photoacoustic bioimaging.

Highly efficient near-infrared BODIPY phototherapeutic nanoparticles for cancer treatment

A highly efficient NIR BODIPY nano-photosensitizer constructed by multi-intersection effects provides beneficial guidance for photodynamic and photothermal therapy.

Activatable molecular agents for cancer theranostics

Theranostics that integrates diagnosis and treatment modalities has attracted great attention due to its abilities of personalized therapy and real-time monitoring of therapeutic outcome. Such a theranostic paradigm requires agents to simultaneously possess the capabilities of targeting, imaging, and treatment. Activatable molecular agents (AMAs) are promising for cancer theranostics, as they show a higher signal-to-noise ratio (SNR), real-time detection of cancer-associated biomarkers, lower normal tissue toxicity, and a higher therapeutic effect. This perspective summarizes the recent advancements of AMAs, which include imaging-guided chemotherapy, imaging-guided photodynamic therapy, and imaging-guided photothermal therapy. The molecular design principles, theranostic mechanisms, and biomedical applications of AMAs are described, followed by a discussion of potential challenges of AMAs in cancer theranostics.

Remote Light-Responsive Nanocarriers for Controlled Drug Delivery: Advances and Perspectives

Engineering of smart photoactivated nanomaterials for targeted drug delivery systems (DDS) has recently attracted considerable research interest as light enables precise and accurate controlled release of drug molecules in specific diseased cells and/or tissues in a highly spatial and temporal manner. In general, the development of appropriate light-triggered DDS relies on processes of photolysis, photoisomerization, photo-cross-linking/un-cross-linking, and photoreduction, which are normally sensitive to ultraviolet (UV) or visible (Vis) light irradiation. Considering the issues of poor tissue penetration and high phototoxicity of these high-energy photons of UV/Vis light, recently nanocarriers have been developed based on light-response to low-energy photon irradiation, in particular for the light wavelengths located in the near infrared (NIR) range. NIR light-triggered drug release systems are normally achieved by using two-photon absorption and photon upconversion processes. Herein, recent advances of light-responsive nanoplatforms for controlled drug release are reviewed, covering the mechanism of light responsive small molecules and polymers, UV and Vis light responsive nanocarriers, and NIR light responsive nanocarriers. NIR-light triggered drug delivery by two-photon excitation and upconversion luminescence strategies is also included. In addition, the challenges and future perspectives for the development of light triggered DDS are highlighted.

Photoswitchable phthalocyanine-assembled nanoparticles for controlled “double-lock” photodynamic therapy

A new nanoparticle platform,NanoAzoPcS, is created by co-assembly of phthalocyanine and azobenzene amphiphiles, which can be used to gain precise control of PDT simply by regulating the stoichiometric ratio of the components and using light irradiation.

Singlet oxygen partition between the outer-, inner- and membrane-phases of photo/chemotherapeutic liposomes

Herein, we developed a strategy to quantify the fraction of singlet oxygen lifetime spent in the three distinct local liposomal environments through the combination of direct and indirect singlet oxygen detection approaches.