Molecular Interactions in Organic Nanoparticles for Phototheranostic Applications

Self-Assembled Organic Nanomaterials for Drug Delivery, Bioimaging, and Cancer Therapy

Over the past few decades, tremendous progress has been made in the development of engineering nanomaterials, which opened new horizons in the field of diagnosis and treatment of various diseases. In particular, self-assembled organic nanomaterials with intriguing features including delicate structure tailoring, facile processability, low cost, and excellent biocompatibility have shown outstanding potential in biomedical applications because of the enhanced permeability and retention (EPR) effect and multifunctional properties. In this review, we briefly introduce distinctive merits of self-assembled organic nanomaterials for biomedical applications. The main focus will be placed on summarizing recent advances in self-assembled organic nanomedicine for drug delivery, bioimaging, and cancer phototherapy, followed by highlighting a critical perspective on further development of self-assembled organic nanomaterials for future clinical translation. We believe that the above themes will appeal to researchers from different fields, including material, chemical, and biological sciences, as well as pharmaceutics.

Simultaneously boosting the conjugation, brightness and solubility of organic fluorophores by using AIEgens

Organic near-infrared (NIR) emitters hold great promise for biomedical applications. Yet, most organic NIR fluorophores face the limitations of short emission wavelengths, low brightness, unsatisfactory processability, and the aggregation-caused quenching effect. Therefore, development of effective molecular design strategies to improve these important properties at the same time is a highly pursued topic, but very challenging. Herein, aggregation-induced emission luminogens (AIEgens) are employed as substituents to simultaneously extend the conjugation length, boost the fluorescence quantum yield, and increase the solubility of organic NIR fluorophores, being favourable for biological applications. A series of donor-acceptor type compounds with different substituent groups (i.e., hydrogen, phenyl, and tetraphenylethene (TPE)) are synthesized and investigated. Compared to the other two analogs, MTPE-TP3 with TPE substituents exhibits the reddest fluorescence, highest brightness, and best solubility. Both the conjugated structure and twisted conformation of TPE groups endow the resulting compounds with improved fluorescence properties and processability for biomedical applications. The in vitro and in vivo applications reveal that the NIR nanoparticles function as a potent probe for tumour imaging. This study would provide new insights into the development of efficient building blocks for improving the performance of organic NIR emitters.

A Sandwich Nanostructure of Gold Nanoparticle Coated Reduced Graphene Oxide for Photoacoustic Imaging-Guided Photothermal Therapy in the Second NIR Window

We explore a sandwich-type gold nanoparticle coated reduced graphene oxide (rGO-AuNP) as an effective nanotheranostic platform for the second near-infrared (NIR-II) window photoacoustic (PA) imaging-guided photothermal therapy (PTT) in ovarian cancer. The PEG was loaded onto the AuNPs surface to increase the stability of nanostructure. The forming rGO-AuNPs- PEG revealed very strong SERS signal, NIR-II PA signal and high photothermal efficiency against tumor upon 1,061 nm laser irradiation. The prominent performance was attributed to the plasmonic coupling of AuNPs, and the enhanced response of rGO and the plasmonic AuNP. Thus, our study demonstrates that the rGO-AuNP nanocomposite could promise to be a potential photothermal agent and pave the way for the diagnosis and therapy of ovarian cancer in the future.

Grafted semiconducting polymer amphiphiles for multimodal optical imaging and combination phototherapy

Semiconducting polymer nanoparticles (SPNs) have gained growing attention in biomedical applications. However, the preparation of SPNs is usually limited to nanoprecipitation in the presence of amphiphilic copolymers, which encounters the issue of dissociation. As an alternative to SPNs, grafted semiconducting polymer amphiphiles (SPAs) composed of a semiconducting polymer (SP) backbone and hydrophilic side chains show increased physiological stability and improved optical properties. This review summarizes recent advances in SPAs for cancer imaging and combination phototherapy. The applications of SPAs in optical imaging including fluorescence, photoacoustic, multimodal and activatable imaging are first described, followed by the discussion of applications in imaging-guided phototherapy and combination therapy, light-triggered drug delivery and gene regulation. At last, the conclusion and future prospects in this field are discussed.

Single-wavelength phototheranostics for colon cancer via the thiolytic reaction

It's a huge challenge to develop effective nanosystems that combine the capabilities of diagnoses and therapies together for colon cancer in the clinic. Herein, we constructed a far-red absorbing phototheranostic nanosystem (FR-H2S) based on the thiolytic reaction of a dinitrophenyl modified phototheranostic prodrug and over-expressed H2S in colon cancer sites for precise imaging-guided phototherapy. FR-H2S with a BODIPY core not only could work as an imaging probe for diagnosis but also act as a phototherapeutic agent for cancer treatment under a single FR laser source (650 nm). FR-H2S exhibited a gradually enhanced fluorescence emission for precise diagnosis of H2S-rich colon tumor sites. After entering tumor cells, FR-H2S could generate abundant 1O2 and heat for phototherapies timely by using the same laser source (650 nm). We believe that this precise imaging-guided phototheranostic nanosystem could provide a promising approach to colon cancer with minimal damage.

Review: Organic nanoparticle based active targeting for photodynamic therapy treatment of breast cancer cells

Targeted Photodynamic therapy (TPDT) is a non-invasive and site-specific treatment modality, which has been utilized to eradicate cancer tumour cells with photoactivated chemicals or photosensitizers (PSs), in the presence of laser light irradiation and molecular tissue oxygen. Breast cancer is the commonest cancer among women worldwide and is currently treated using conventional methods such as chemotherapy, radiotherapy and surgery. Despite the recent advancements made in PDT, poor water solubility and non-specificity of PSs, often affect the overall effectivity of this unconventional cancer treatment. With respect to conventional PS obstacles, great strides have been made towards the application of targeted nanoparticles in PDT to resolve these limitations. Therefore, this review provides an overview of scientific peer reviewed published studies in relation to functionalized organic nanoparticles (NPs) for effective TPDT treatment of breast cancer over the last 10 years (2009 to 2019). The main aim of this review is to highlight the importance of organic NP active based PDT targeted drug delivery systems, to improve the overall biodistribution of PSs in breast cancer tumour's.

Photophysics of J-Aggregating Porphyrin-Lipid Photosensitizers in Liposomes: Impact of Lipid Saturation

Porphyrin aggregates have attractive photophysical properties for phototherapy and optical imaging, including quenched photosensitization, efficient photothermal conversion, and unique absorption spectra. Although hydrophobic porphyrin photosensitizers have long been encapsulated into liposomes for drug delivery, little is known about the membrane properties of liposomes with large amphiphilic porphyrin compositions. In this paper, a porphyrin-lipid conjugate was incorporated into liposomes formed of saturated or unsaturated lipids to study the membrane composition-dependent formation of highly ordered porphyrin J-aggregates and disordered aggregates. Porphyrin-lipid readily phase-separates in saturated membranes, forming J-aggregates that are destabilized during the ripple phase below the main thermal transition. Porphyrin-lipid J-aggregates are photostable with a photothermal efficiency of 54 ± 6%, comparable to gold. Even at high porphyrin-lipid compositions, porphyrin J-aggregates coexist with a minority population of disordered aggregates, which are photodynamically active despite being fluorescently quenched. For photothermal applications, liposome formulations that encourage porphyrin-lipid phase separation should be explored for maximum J-aggregation.

Mitoxantrone as photothermal agents for ultrasound/fluorescence imaging-guided chemo-phototherapy enhanced by intratumoral H2O2-Induced CO

Multimodal imaging integrated theranostic nanomaterials provides broad prospects for noninvasive and precise cancer treatment. However, the uncertain physiological metabolism of the existing phototherapy nanoagents greatly prevents its clinical application. Herein, a smart nanoplatform based on clinically chemotherapeutic drugs mitoxantrone (MTO) was prepared to realize ultrasound/fluorescence imaging-guided chemo-photothermal combined therapy. The nanoplatform encapsulating MTO and manganese carbonyl (MnCO), which denoted as MCMA NPs, could accumulate at tumor sites by enhanced permeability and retention (EPR) effect and effectively induce cell apoptosis. MTO with near-infrared absorption (~676 nm) not only acted as chemotherapy drug, but also served as photothermal reagent with high photothermal conversion efficiency (ƞ = 42.2%). Especially, H₂O₂ in tumor sites and the photothermal effect of MTO could trigger MnCO to generate CO, which made cancer cells more sensitive to MTO and significantly alleviated cell resistance. Simultaneously, CO released in tumor also could act as contrast agent for tumor ultrasound imaging to provide accurate guidance for anticancer treatment. Moreover, MCMA NPs could further promote oxidative stress damage in mitochondria and protect normal cells from side effects of chemotherapy. Both in vivo and in vitro studies indicated that MCMA NPs possessed excellent synergetic tumor inhibition ability with high efficiency and low chemotherapy resistance.

Evoking Photothermy by Capturing Intramolecular Bond Stretching Vibration-Induced Dark-State Energy

Development of highly effective approaches to desirable photothermal conversion agents is particularly valuable. Herein, we report a concept, namely, bond stretching vibration-induced photothermy, that serves as a mechanism to construct advanced photothermal conversion agents. As a proof-of-concept, two compounds (DCP-TPA and DCP-PTPA) with donor-acceptor (D-A) structures were synthesized. The bond stretching vibration of the pyrazine-containing unit in these molecules is vigorous and insensitive to the external environmental restraint, which efficiently transforms the absorbed photons to dark-state heat energy. The nanoparticles (NPs) of DCP-TPA and DCP-PTPA show rather high photothermal conversion efficiency (52% and 59%) and stronger photoacoustic (PA) signal than commercial methylene blue and reported high-performance semiconducting polymer nanoparticles. The DCP-PTPA NPs perform better than DCP-TPA NPs in terms of photothermal conversion, PA signal production, and in vivo PA tumor imaging because of the increased bond stretching vibration in the former molecule.

RBC Membrane Camouflaged Semiconducting Polymer Nanoparticles for Near-Infrared Photoacoustic Imaging and Photothermal Therapy

Semiconducting conjugated polymer nanoparticles (SPNs) represent an emerging class of phototheranostic materials with great promise for cancer treatment. In this report, low-bandgap electron donor-acceptor (D-A)-conjugated SPNs with surface cloaked by red blood cell membrane (RBCM) are developed for highly effective photoacoustic imaging and photothermal therapy. The resulting RBCM-coated SPN (SPN@RBCM) displays remarkable near-infrared light absorption and good photostability, as well as high photothermal conversion efficiency for photoacoustic imaging and photothermal therapy. Particularly, due to the small size (< 5 nm), SPN@RBCM has the advantages of deep tumor penetration and rapid clearance from the body with no appreciable toxicity. The RBCM endows the SPNs with prolonged systematic circulation time, less reticuloendothelial system uptake and reduced immune-recognition, hence improving tumor accumulation after intravenous injection, which provides strong photoacoustic signals and exerts excellent photothermal therapeutic effects. Thus, this work provides a valuable paradigm for safe and highly efficient tumor photoacoustic imaging and photothermal therapy for further clinical translation.

Implantable fibrous 'patch' enabling preclinical chemo-photothermal tumor therapy

Localized drug delivery systems (LDDSs), in the forms of fibers or hydrogel, have emerged as an alternative approach for effective cancer treatment, but suffer challenges in the limited efficacy originated from sole therapeutic functionality. Herein, a multifunctional LDDS, showing feasibility for minimally-invasive implantation, was designed and synthesized for on-site chemo-photothermal synergistic therapy. In this system, polydopamine (PDA) nanoparticles, loaded with doxorubicin (DOX), were assembled at the surface of electrospun PCL-gelatin (PG) fibers (PG@PDA-DOX). The composite PG@PDA-DOX nanofibers could effectively transform NIR light into heat and present excellent photostability. In addition, low pH and NIR irradiation enabled remarkably accelerated DOX release. The in vitro study of PG@PDA-DOX fibers showed effective anti-cancer effect with irradiation of 808 nm NIR by inducing cell apoptosis and suppressing cell proliferation. The in vivo study, by implanting PG@PDA-DOX nanofibers in the patient derived xenograft (PDX) model via minimally-invasive surgery, presented that the composite fibers can effectively inhabit tumor growth by the combined chemo-photothermal effect without clear systematic side-effects. This study has therefore demonstrated a minimally-invasive platform, in a fibrous mesh form, with both high therapeutic efficacy and considerable potential in clinical translation for liver cancer treatment.

Simple Method to Supply Organic Nanoparticles with Excitation-Wavelength-Dependent Photoluminescence

Organic fluorescent nanoparticles (FNPs) have become increasingly prevalent in a variety of applications but the creation of organic FNPs using a simple procedure and that possess diverse morphology, multicolor luminescence, and high brightness has been challenging. Herein, a facile strategy to prepare this class of organic FNPs is established by way of preformed organic nanoparticles themselves. It was found that as long as the nanoparticles contained aromatic/heterocyclic rings in their base unit and regardless of morphologies (e.g., small-molecule micelles, polymeric micelles, reverse micelles, solid microspheres, and vesicles), simple UV irradiation can result in the particles exhibiting excitation-wavelength-dependent photoluminescence with considerable quantum yields (∼8.3-16.7% for tested particles). Upon initial investigation of the mechanism, the photoluminescence behavior was attributed to a polycyclic aromatic hydrocarbon (PAH) process. Furthermore, the application of the synthesized organic FNPs in cancer cell imaging is demonstrated as just one of the many potential applications. The straightforward method to supply preformed organic nanoparticles with photoluminescence would be attractive for scientists in both academia and industry.

Supramolecular Phthalocyanine Assemblies for Improved Photoacoustic Imaging and Photothermal Therapy

Phototheranostic nanoplatforms are of particular interest for cancer diagnosis and imaging-guided therapy. Herein, we develop a supramolecular approach to fabricate a nanostructured phototheranostic agent through the direct self-assembly of two water-soluble phthalocyanine derivatives, PcS4 and PcN4. The nature of the molecular recognition between PcS4 and PcN4 facilitates the formation of nanostructure (PcS4-PcN4) and consequently enables the fabrication of PcS4-PcN4 with completely quenched fluorescence and reduced singlet oxygen generation, leading to the high photoacoustic and photothermal activity of PcS4-PcN4. In vivo evaluations suggest that PcS4-PcN4 could not only efficiently visualize a tumor with high contrast through whole-body photoacoustic imaging but also enable excellent photothermal therapy for cancer.

Polyoxovanadate-iodobodipy supramolecular assemblies: new agents for high efficiency cancer photochemotherapy

Two novel polyoxovanadate-iodoBodipy supramolecular assemblies, named as (2I-BDP-C6)2V6 and (2I-BDP-C6)3V10, were first synthesized by the self-assembly of anionic hexavanadate and decavanadate with cationic iodoBodipy for photochemotherapy, respectively. The mechanisms for synergistic photochemotherapy of the anion-cation pairs were determined. In particular, (2I-BDP-C6)3V10 can effectively kill lung cancer cells (HepG2) by synergetic chemotherapy as well as photodynamic therapy.

Metal-Organic Frameworks for Photodynamic Therapy: Emerging Synergistic Cancer Therapy

Photodynamic therapy (PDT) conducted by photosensitizers producing cytotoxic reactive oxygen species (ROS) under light irradiation is widely used in cancer treatment. A great number of photoactive nanoscale metal-organic frameworks (NMOFs) have been prepared for PDT. With the development of biomedicine and nanotechnology, many synergistic cancer therapies have emerged. In this mini-review, an overview on the latest progress in the application of NMOFs in PDT is provided, with emphasis on the recent emergence of some synergistic therapies.

Calixarene-Based Supramolecular AIE Dots with Highly Inhibited Nonradiative Decay and Intersystem Crossing for Ultrasensitive Fluorescence Image-Guided Cancer Surgery

Host-guest complexation between calix[5]arene and aggregation-induced emission luminogen (AIEgen) can significantly turn off both the energy dissipation pathways of intersystem crossing and thermal deactivation, enabling the absorbed excitation energy to mostly focus on fluorescence emission. The co-assembly of calix[5]arene amphiphiles and AIEgens affords highly emissive supramolecular AIE nanodots thanks to their interaction severely restricting the intramolecular motion of AIEgens, which also show negligible generation of cytotoxic reactive oxygen species. In vivo studies with a peritoneal carcinomatosis-bearing mouse model indicate that such supramolecular AIE dots have rather low in vivo side toxicity and can serve as a superior fluorescent bioprobe for ultrasensitive fluorescence image-guided cancer surgery.

Light-activated nanozymes: catalytic mechanisms and applications

Recently, nanozymes have attracted enormous interest for their high stability, low cost and various enzyme-like activities. In nature, many biochemical reactions require light. Recently, introducing light to nanozymes has also been reported, especially for photosensitized oxygen activation. Compared to normal nanozymes, light-activated nanozymes possess several advantages including light-regulated activity, using molecular oxygen as a green oxidant, and often higher activity can be achieved. Herein, we summarize light-activated nanozymes, starting from their photophysical processes and identification of reactive oxygen species (ROS). Although the types of light-activated nanozymes are still quite limited and cannot yet mimic the same reactions as natural photo-related enzymes, they have widened the range of nanozymes. A few specific applications are highlighted, including sensing, chemical synthesis, degradation of organic pollutants, and cleavage and repair of DNA. Finally, a few future research opportunities are discussed.

Activatable Phototheranostic Materials for Imaging-Guided Cancer Therapy

Cancer theranostics, which combines diagnostic and therapeutic effects into one entity, holds promise in precision medicine. Conventional theranostic agents possess always-on imaging signals and cytotoxic effects and thus often encounter poor selectivity or specificity in cancer treatment. To tackle this issue, activatable phototheranostic materials (PMs) have been developed to simultaneously and specifically turn on their diagnostic signals (fluorescence/self-luminescence/photoacoustic signals) and photothermal/photodynamic effects in response to cancer hallmarks. This Review summarizes the recent progress in the design, synthesis and proof-of-concept applications of activatable PMs. The molecular engineering strategy to increase tumor accumulation and enhance treatment efficacy are highlighted. Current challenges and future perspectives in this emerging field are also discussed.

Enhanced Antitumor Efficacy and Imaging Application of Photosensitizer-Formulated Paclitaxel

Paclitaxel (PTX) is a widely used anticancer drug that works by inhibiting microtubule disassembly. PTX safety was greatly enhanced by embedding it with human albumin. Here, we study the synergistic effects of PTX with photodynamic therapy (PDT) both in vitro and in vivo by constructing photosensitizer-PTX nanotheranostics (PPNTs). PPNTs were fabricated via noncovalent hydrophobic interactions and π-π stacking between an amphipathic photosensitizer and PTX with an average diameter of ∼80 nm, and these showed high stability in biological conditions. In a tumor-bearing mouse model, PPNTs were shown to accumulate at the tumor site based on three-dimensional fluorescence tomographic imaging. Under 680 nm light irradiation, PPNTs exhibited a superior solid tumor ablation effect in a mouse model, with a dose of PTX (0.2 mg/kg) that is 10-fold lower than that typically used. Mechanistically, PPNTs induced a strong apoptotic response in cells under light illumination and showed an increased antitumor efficacy that is 47.2-fold and 57.6-fold higher than that of the photosensitizer nanoparticles (PNTs) and free PTX, respectively. In addition, PPNTs showed enhanced cellular uptake with focused mitochondria and lysosome colocalization compared to that of PNTs and the amount of PTX delivered in PPNTs was sufficient to induce cell cycle arrest in the G2/M phase. These findings indicated that the current combination therapy has advantages over monotherapy in promoting tumor regression and ultimately achieving tumor elimination.

Polystyrene and Poly(ethylene glycol)-b-Poly(ε-caprolactone) Nanoparticles with Porphyrins: Structure, Size, and Photooxidation Properties

The transport of a photosensitizer to target biological structures followed by the release of singlet oxygen is a critical step in photodynamic therapy. We compared the (photo)physical properties of polystyrene nanoparticles (TPP@PS) of different sizes and self-assembled poly(ethylene glycol)-b-poly(ε-caprolactone) core/shell nanoparticles (TPP@PEG-PCL) with different lengths of copolymer blocks, both suitable for the transport of the tetraphenylporphyrin (TPP) photosensitizer. The singlet oxygen was formed inside both nanoparticles after irradiation with visible light. Its kinetics was controlled by the size of TPP@PS; its lifetime (τ_Δ) increased with increasing nanoparticle size (from 6.5 to 16 μs) because of hindered diffusion into the external aqueous environment, where it was quickly deactivated. Accordingly, the prolongation of the singlet oxygen-sensitized delayed fluorescence kinetics was found for TPP@PS of high size. The TPP@PEG-PCL self-assemblies allowed for enhanced oxygen diffusion, and the estimated low values of τ_Δ ≈ 3.7 μs were independent of the size of building blocks. The delayed fluorescence in oxygen-free conditions originating from triplet-triplet annihilation indicated a high mobility of TPP in the PCL core in comparison with fixed molecules in the PS matrix. Photooxidation of uric acid revealed the highest efficacy for TPP@PS of small sizes, whereas the largest TPP@PS exhibited the lowest activity, and the efficacy of TPP@PEG-PCL remained independent of the sizes of the building blocks.

Electrochemically assisted synthesis of poly(3,4-dihydroxyphenylalanine) fluorescent organic nanoparticles for sensing applications

Facile preparation of polyDOPA-FONs is achieved via the electrochemical oxidation method.

pH-responsive perylenediimide nanoparticles for cancer trimodality imaging and photothermal therapy

Organic chromophores have been well developed for multimodality imaging-guided photothermal therapy (PTT) due to their outstanding optical properties and excellent designability. However, the theranostic efficiencies of most currently available organic chromophores are restricted intrinsically, owing to their poor photostability or complex synthesis procedures. These drawbacks not only increase their cost of synthesis, but also cause side effects in PTT. Method: We presented a facile strategy for constructing a near-infrared (NIR)-absorbing perylenediimide structured with pH-responsive piperazine ring at the bay region. The chromophore was conjugated with carboxyl-end-capped PEG as side chains that can self-assemble into nanoparticles (NPs) in aqueous solution. The NIR optical properties and photothermal conversation ability of PPDI-NPs were investigated. We then studied the imaging-guided PTT of PPDI-NPs under NIR light illumination in 4T1 cells and mice respectively. Results: The excellent photostable PPDI-NPs had near-infrared fluorescence (NIRF) emission and high photothermal conversion efficiency in acidic microenvironment. Importantly, PPDI-NPs can be utilized for the precise detection of tumors by NIRF/photoacoustic/thermal trimodality imaging. Efficient PTT of PPDI-NPs was applied in vitro and in vivo with high biosafety. Conclusion: In summary, we developed pH-responsive perylenediimide nanoparticles as multifunctional phototheranostic agent with high stability and simple synthesis procedures. This study offers a promising organic chromophore for developing phototheranostics in cancer therapy.

Multifunctional phototheranostic nanomedicine for cancer imaging and treatment

Cancer, as one of the most life-threatening diseases, shows a high fatality rate around the world. When improving the therapeutic efficacy of conventional cancer treatments, researchers also conduct extensive studies into alternative therapeutic approaches, which are safe, valid, and economical. Phototherapies, including photodynamic therapy (PDT) and photothermal therapy (PTT), are tumor-ablative and function-reserving oncologic interventions, showing strong potential in clinical cancer treatment. During phototherapies, the non-toxic phototherapeutic agents can be activated upon light irradiation to induce cell death without causing much damage to normal tissues. Besides, with the rapid development of nanotechnology in the past decades, phototheranostic nanomedicine also has attracted tremendous interests aiming to continuously refine their performance. Herein, we reviewed the recent progress of phototheranostic nanomedicine for improved cancer therapy. After a brief introduction of the therapeutic principles and related phototherapeutic agents for PDT and PTT, the existing works on developing of phototheranostic nanomedicine by mainly focusing on their categories and applications, particularly on phototherapy-synergized cancer immunotherapy, are comprehensively reviewed. More importantly, a brief conclusion and future challenges of phototheranostic nanomedicine from our point of view are delivered in the last part of this article.

Recent advances of polyoxometalates in multi-functional imaging and photothermal therapy

The recent advances of polyoxometalate clusters in terms of near infrared photothermal properties for targeted tumor therapy have been summarized while the combined applications with various bio-imaging techniques and chemotherapies are reviewed.

Charge transfer co-crystals based on donor–acceptor interactions for near-infrared photothermal conversion

The charge transfer from the donor to the acceptor units results in a CT complex with excellent near-infrared photothermal conversion efficiency, which acted as an excellent photothermal material in seawater desalination application.

Bioapplications of small molecule Aza-BODIPY: from rational structural design to in vivo investigations

This review highlights the empirical design guidelines and photophysical property manipulation of Aza-BODIPY dyes and the latest advances in their bioapplications.

Design of superior phototheranostic agents guided by Jablonski diagrams

This review summarizes how Jablonski diagrams guide the design of advanced organic optical agents and improvement of disease phototheranostic efficacies.

Emerging combination strategies with phototherapy in cancer nanomedicine

Based on the challenges in single-mode phototherapy, this review summarizes the significant research progress in combinatorial strategies with phototherapy.

Dinuclear metal complexes: multifunctional properties and applications

Dinuclear metal complexes have enabled breakthroughs in OLEDs, photocatalytic water splitting and CO₂reduction, DSPEC, chemosensors, biosensors, PDT and smart materials.

Near-IR absorbing J-aggregates of a phenanthrene-fused BODIPY as a highly efficient photothermal nanoagent

A phenanthrene-[b]-fused BODIPY exhibited well-defined J-aggregates in both pure hydrocarbon solution and aqueous solution, and was developed as a highly efficient photothermal nanoagent.

Regulating the Photophysical Property of Organic/Polymer Optical Agents for Promoted Cancer Phototheranostics

On the basis of the Jablonski diagram, the photophysical properties of optical agents are highly associated with biomedical function and efficacy. Herein, the focus is on organic/polymer optical agents and the recent progress in the main strategies for regulating their photophysical properties to achieve superior cancer diagnosis/phototheranostics applications are highlighted. Both the approaches of nanoengineering and molecular design, which can lead to optimized effectiveness of required biomedical function, are discussed.

Self-assembled injectable biomolecular hydrogels towards phototherapy

Biomolecular hydrogels assembled from biomolecules, such as proteins, peptides, and polysaccharides, are promising candidates for facilitating biomedical applications due to their advantages of high biocompatibility, adjustable mechanical properties, functional diversity, and good degradability. This review focuses on current progress in the field of supramolecular injectable biomolecular hydrogels and their applications in antitumor photodynamic therapy (PDT), photothermal therapy (PTT), combined PDT and PTT, and antibacterial phototherapy with emphasis on biomolecular hydrogelators, injectable behaviors, phototherapeutic functions, and the remaining challenges. We hope that this review can provide useful inspiration for the construction and biological applications of novel photo-functional hydrogels as well as phototherapies.

Promoting Noncovalent Intermolecular Interactions Using a C60 Core Particle in Aqueous PC60s-Covered Colloids for Ultraefficient Photoinduced Particle Activity

Noncovalent intermolecular interactions in nanomaterials, such as van der Waals effects, allow adjustment of the nanoscopic size of compounds and their conformation in molecular crystal regimes. These strong interactions permit small particle sizes to be maintained as the crystals grow. In particular, these effects can be leveraged in the confined/reinforcing phase of molecules. With this in mind, we used C₆₀ molecules as a core particle in single-PC60 surfactant-covered colloid in a water-processable system. Compared with our previous results based on a PC₆₁BM core-PC60 shell particle, the PC60-C₆₀ colloid had a considerably smaller spherical structure due to the increased intermolecular interactions between C₆₀ (fullerene) molecules. Interestingly, the conformation of C₆₀ aggregates was altered depending on the mixed solvents and their volume fraction in the organic phase, which strongly affected the structural properties of the PC60-C₆₀ colloids. The particle facilitated strong interactions with a p-type core sphere when it was introduced as the shell part of a p-n heterojunction particle. This direct interaction provided effective electronic communication between p- and n-type particles, resulting in ultraefficient photonic properties, particularly in charge separation in aqueous heterostructured colloids. This enabled the development of an extremely efficient photovoltaic device with a 6.74% efficiency, which could provide the basis for creating high-performance water-processable solar cells based on p-n heterostructured NPs.

Manipulating Nonradiative Decay Channel by Intermolecular Charge Transfer for Exceptionally Improved Photothermal Conversion

In-depth studies of nonradiative (NR) decay, seeking to maximize NR decay rate or manipulate other NR decay channels, are of greatest significance for improving the photothermal conversion efficiency (η) of organic materials for phototheranostics; however, to date, relevant work remains scarce. Here, we present an insightful study of NR decay in BODIPY (BDP) dye, in an aggregated state, i.e., in BDP nanoparticles (BDP NPs), which show an efficient additional NR decay channel from the aggregation-stabilized intermolecular charge transfer (CT) state, resulting in exceptionally high η (61%) for highly efficient phototheranostics in vivo. BDP NPs exhibit two ultrafast NR decay channels with ultrashort lifetimes of 1.7 and 50 ps, which is in stark contrast to the only S₁ → S₀ NR channel with a long lifetime of 373 ps in the isolated BDP dye. More importantly, the ultrafast NR channel (1.7 ps) in BDP NPs depletes a substantial portion of the excited-state population (71%), which accounts for its much better photothermal effect as compared with the isolated BDP dye. Finally, BDP NPs display a highly efficient photoacoustic imaging (PAI) guided photothermal therapy (PTT) of tumors in live mice. This study presents a deeper fundamental understanding of NR decay in organic materials, setting a valuable guideline that may be widely applicable to similar molecular structure to develop more advanced organic materials not only for photothermal-related applications.

Theranostic Nanoplatform with Hydrogen Sulfide Activatable NIR Responsiveness for Imaging-Guided On-Demand Drug Release

NIR light responsive nanoplatforms hold great promise for on-demand drug release in precision cancer medicine. However, currently available systems utilize "always-on" photothermal transducers that lack target specificity, and thus inaccurately differentiate tumors from normal tissues. Developed here is a theranostic nanoplatform featuring H₂ S-mediated in situ production of NIR photothermal agents for imaging-guided and photocontrolled drug release. The system targets H₂ S-rich cancers. This nanoplatform shows H₂ S-activatable NIR-II emission and NIR light controllable release of the drug Camptothecin-11. Upon administering the system to HCT116 tumor-bearing mice, the tumor is greatly suppressed with minimal side effects, arising from the synergy of the cancer-specific and NIR light activated therapy. This theranostic nanoplatform thus sheds light on precision medicine with guidance through NIR-II imaging.