Synergistic Targeting and Efficient Photodynamic Therapy Based on Graphene Oxide Quantum Dot-Upconversion Nanocrystal Hybrid Nanoparticles

Graphene-Based Photodynamic Therapy and Overcoming Cancer Resistance Mechanisms: A Comprehensive Review

Photodynamic therapy (PDT) is a non-invasive therapy that has made significant progress in treating different diseases, including cancer, by utilizing new nanotechnology products such as graphene and its derivatives. Graphene-based materials have large surface area and photothermal effects thereby making them suitable candidates for PDT or photo-active drug carriers. The remarkable photophysical properties of graphene derivates facilitate the efficient generation of reactive oxygen species (ROS) upon light irradiation, which destroys cancer cells. Surface functionalization of graphene and its materials can also enhance their biocompatibility and anticancer activity. The paper delves into the distinct roles played by graphene-based materials in PDT such as photosensitizers (PS) and drug carriers while at the same time considers how these materials could be used to circumvent cancer resistance. This will provide readers with an extensive discussion of various pathways contributing to PDT inefficiency. Consequently, this comprehensive review underscores the vital roles that graphene and its derivatives may play in emerging PDT strategies for cancer treatment and other medical purposes. With a better comprehension of the current state of research and the existing challenges, the integration of graphene-based materials in PDT holds great promise for developing targeted, effective, and personalized cancer treatments.

Innovative approaches for cancer treatment: graphene quantum dots for photodynamic and photothermal therapies

Graphene quantum dots (GQDs) hold great promise for photodynamic and photothermal cancer therapies. Their unique properties, such as exceptional photoluminescence, photothermal conversion efficiency, and surface functionalization capabilities, make them attractive candidates for targeted cancer treatment. GQDs have a high photothermal conversion efficiency, meaning they can efficiently convert light energy into heat, leading to localized hyperthermia in tumors. By targeting the tumor site with laser irradiation, GQD-based nanosystems can induce selective cancer cell destruction while sparing healthy tissues. In photodynamic therapy, light-sensitive compounds known as photosensitizers are activated by light of specific wavelengths, generating reactive oxygen species that induce cancer cell death. GQD-based nanosystems can act as excellent photosensitizers due to their ability to absorb light across a broad spectrum; their nanoscale size allows for deeper tissue penetration, enhancing the therapeutic effect. The combination of photothermal and photodynamic therapies using GQDs holds immense potential in cancer treatment. By integrating GQDs into this combination therapy approach, researchers aim to achieve enhanced therapeutic efficacy through synergistic effects. However, biodistribution and biodegradation of GQDs within the body present a significant hurdle to overcome, as ensuring their effective delivery to the tumor site and stability during treatment is crucial for therapeutic efficacy. In addition, achieving precise targeting specificity of GQDs to cancer cells is a challenging task that requires further exploration. Moreover, improving the photothermal conversion efficiency of GQDs, controlling reactive oxygen species generation for photodynamic therapy, and evaluating their long-term biocompatibility are all areas that demand attention. Scalability and cost-effectiveness of GQD synthesis methods, as well as obtaining regulatory approval for clinical applications, are also hurdles that need to be addressed. Further exploration of GQDs in photothermal and photodynamic cancer therapies holds promise for advancements in targeted drug delivery, personalized medicine approaches, and the development of innovative combination therapies. The purpose of this review is to critically examine the current trends and advancements in the application of GQDs in photothermal and photodynamic cancer therapies, highlighting their potential benefits, advantages, and future perspectives as well as addressing the crucial challenges that need to be overcome for their practical application in targeted cancer therapy.

Graphene oxide nanoarchitectures in cancer therapy: Drug and gene delivery, phototherapy, immunotherapy, and vaccine development

The latest advancements in oncology involves the creation of multifunctional nanostructures. The integration of nanoparticles into the realm of cancer therapy has brought about a transformative shift, revolutionizing the approach to addressing existing challenges and limitations in tumor elimination. This is particularly crucial in combating the emergence of resistance, which has significantly undermined the effectiveness of treatments like chemotherapy and radiotherapy. GO stands as a carbon-derived nanoparticle that is increasingly finding utility across diverse domains, notably in the realm of biomedicine. The utilization of GO nanostructures holds promise in the arena of oncology, enabling precise transportation of drugs and genetic material to targeted sites. GO nanomaterials offer the opportunity to enhance the pharmacokinetic behavior and bioavailability of drugs, with documented instances of these nanocarriers elevating drug accumulation at the tumor location. The GO nanostructures encapsulate genes, shielding them from degradation and facilitating their uptake within cancer cells, thereby promoting efficient gene silencing. The capability of GO to facilitate phototherapy has led to notable advancements in reducing tumor progression. By PDT and PTT combination, GO nanomaterials hold the capacity to diminish tumorigenesis. GO nanomaterials have the potential to trigger both cellular and innate immunity, making them promising contenders for vaccine development. Additionally, types of GO nanoparticles that respond to specific stimuli have been applied in cancer eradication, as well as for the purpose of cancer detection and biomarker diagnosis. Endocytosis serves as the mechanism through which GO nanomaterials are internalized. Given these advantages, the utilization of GO nanomaterials for tumor elimination comes highly recommended.

Nanobiotechnological approaches in osteosarcoma therapy: Versatile (nano)platforms for theranostic applications

Constructive achievements in the field of nanobiotechnology and their translation into clinical course have led to increasing attention towards evaluation of their use for treatment of diseases, especially cancer. Osteosarcoma (OS) is one of the primary bone malignancies that affects both males and females in childhood and adolescence. Like other types of cancers, genetic and epigenetic mutations account for OS progression and several conventional therapies including chemotherapy and surgery are employed. However, survival rate of OS patients remains low and new therapies in this field are limited. The purpose of the current review is to provide a summary of nanostructures used in OS treatment. Drug and gene delivery by nanoplatforms have resulted in an accumulation of therapeutic agents for tumor cell suppression. Furthermore, co-delivery of genes and drugs by nanostructures are utilized in OS suppression to boost immunotherapy. Since tumor cells have distinct features such as acidic pH, stimuli-responsive nanoparticles have been developed to appropriately target OS. Besides, nanoplatforms can be used for biosensing and providing phototherapy to suppress OS. Furthermore, surface modification of nanoparticles with ligands can increase their specificity and selectivity towards OS cells. Clinical translation of current findings suggests that nanoplatforms have been effective in retarding tumor growth and improving survival of OS patients.

Revisiting the factors influencing the magnetic resonance contrast of Gd2O3 nanoparticles

Gadolinium oxide nanoparticles (GONs) have the potential to be one of the best candidates for the contrast agents of magnetic resonance imaging. Even though the influence of parameters on the relaxation has been substantially demonstrated, the variation of the r ₁ of GONs with a similar structure and surface chemistry implied our limited understanding. We herein synthesized GONs with adjustable size, shape, and crystallinity, modified them with a series of molecules with different acidities, and recorded their r ₁ values and imaging contrast. Our results showed that the isoelectric point could be regarded as an indicator of the relaxation covering the influence of both surface modification and size, which highlighted the impact of protons dissociated from the contrast agents. We further showed that the nanoparticles with lower crystallinity possess higher relaxivity, and this phenomenon manifested significantly under a low field. Our work clarified that the longitudinal relaxivity of Gd₂O₃ nanoparticles is sensitively dependent on the numbers of H⁺ generated from the surface and in the environment, which may shed light on developing high-performance nanoparticulate T ₁ contrast agents.

Inorganic Nanomaterials with Intrinsic Singlet Oxygen Generation for Photodynamic Therapy

Inorganic nanomaterials with intrinsic singlet oxygen (1 O2 ) generation capacity, are emerged yet dynamically developing materials as nano-photosensitizers (NPSs) for photodynamic therapy (PDT). Compared to previously reported nanomaterials that have been used as either carriers to load organic PSs or energy donors to excite the attached organic PSs through a Foster resonance energy transfer process, these NPSs possess intrinsic 1 O2 generation capacity with extremely high 1 O2 quantum yield (e.g., 1.56, 1.3, 1.26, and 1.09) than any classical organic PS reported to date, and thus are facilitating to make a revolution in PDT. In this review, the recent advances in the development of various inorganic nanomaterials as NPSs, including metal-based (gold, silver, and tungsten), metal oxide-based (titanium dioxide, tungsten oxide, and bismuth oxyhalide), metal sulfide-based (copper and molybdenum sulfide), carbon-based (graphene, fullerene, and graphitic carbon nitride), phosphorus-based, and others (hybrids and MXenes-based NPSs) are summarized, with an emphasis on the design principle and 1 O2 generation mechanism, and the photodynamic therapeutic performance against different types of cancers. Finally, the current challenges and an outlook of future research are also discussed. This review may provide a comprehensive account capable of explaining recent progress as well as future research of this emerging paradigm.

Nano-photosensitizers for enhanced photodynamic therapy

Photodynamic therapy (PDT) utilizes photosensitizers (PSs) together with irradiation light of specific wavelength interacting with oxygen to generate cytotoxic reactive oxygen species (ROS), which could trigger apoptosis and/or necrosis-induced cell death in target tissues. During the past two decades, multifunctional nano-PSs employing nanotechnology and nanomedicine developed, which present not only photosensitizing properties but additionally accurate drug release abilities, efficient response to optical stimuli and hypoxia resistance. Further, nano-PSs have been developed to enhance PDT efficacy by improving the ROS yield. In addition, nano-PSs with additive or synergistic therapies are significant for both currently preclinical study and future clinical practice, given their capability of considerable higher therapeutic efficacy under safer systemic drug dosage. In this review, nano-PSs that allow precise drug delivery for efficient absorption by target cells are introduced. Nano-PSs boosting sensitivity and conversion efficiency to PDT-activating stimuli are highlighted. Nano-PSs developed to address the challenging hypoxia conditions during PDT of deep-sited tumors are summarized. Specifically, PSs capable of synergistic therapy and the emerging novel types with higher ROS yield that further enhance PDT efficacy are presented. Finally, future demands for ideal nano-PSs, emphasizing clinical translation and application are discussed.

Mito-Bomb: Targeting Mitochondria for Cancer Therapy

Cancer has been one of the most common life-threatening diseases for a long time. Traditional cancer therapies such as surgery, chemotherapy (CT), and radiotherapy (RT) have limited effects due to drug resistance, unsatisfactory treatment efficiency, and side effects. In recent years, photodynamic therapy (PDT), photothermal therapy (PTT), and chemodynamic therapy (CDT) have been utilized for cancer treatment owing to their high selectivity, minor resistance, and minimal toxicity. Accumulating evidence has demonstrated that selective delivery of drugs to specific subcellular organelles can significantly enhance the efficiency of cancer therapy. Mitochondria-targeting therapeutic strategies are promising for cancer therapy, which is attributed to the essential role of mitochondria in the regulation of cancer cell apoptosis, metabolism, and more vulnerable to hyperthermia and oxidative damage. Herein, the rational design, functionalization, and applications of diverse mitochondria-targeting units, involving organic phosphine/sulfur salts, quaternary ammonium (QA) salts, peptides, transition-metal complexes, guanidinium or bisguanidinium, as well as mitochondria-targeting cancer therapies including PDT, PTT, CDT, and others are summarized. This review aims to furnish researchers with deep insights and hints in the design and applications of novel mitochondria-targeting agents for cancer therapy.

The dependence of radio-sensitization efficiency on mitochondrial targeting with NaGdF4:Yb,Er nanoparticles

Radio-sensitization is highly desired to reduce side-effect of the harsh dose of radiation therapy (RT), for which nanoparticles with high atomic number elements provide a promising tool. However, insufficient knowledge on utilizing the interaction between nanoparticles and cancerous cells hampers the improvement of therapeutic outcome. We herein employed NaGdF₄:Yb,Er nano-crystals as the sensitizer, and modified them with a tumor targeting agent and a mitochondria targeting moiety, separately and jointly, to achieve varied extent of mitochondrial accumulation. We observed that NaGdF₄:Yb,Er nano-crystal, even unmodified with targeting ligands, is effective for radio-sensitization. Furthermore, the extent of mitochondrial targeting was responsible for sensitization efficiency both in vitro and in vitro. By RNA sequencing technique, the result was ascribed to the reactive oxygen species (ROS) mediated TNF-JNK pathway and cell cycle arrest besides breaking DNA, in contrast to only DNA damage only with those untargeted nanoparticles. Our work indicated that ROS generated by the irradiation can be utilized by activating an alternative apoptotic pathway with mitochondrial targeting nanoparticles, and therefore may suggest an approach for the enhancement of radio-sensitization. STATEMENT OF SIGNIFICANCE: Radiosensitization by nanoparticles could reduce the burden of cancer due to lowering the dose of radiation therapy and reducing side-effect. How to fully utilize the interactions of irradiation-nanoparticles-biotissues remains a challenge for improving the outcome of radiosensitization. In this manuscript, by modifying tumor-targeting and mitochondria-targeting ligands on nanoparticles, separately and jointly, we demonstrated that the radiosensitization efficiency of NaGdF₄:Yb,Er nanoparticle depends on the extent of accumulation near mitochondria. By RNA-seq technique, the RT sensitization with mitochondrial targeting was ascribed to ROS-mediated TNF-JNK pathway and cell cycle arrest, in contrast to only DNA breaks with untargeted nanoparticles. The results suggested a strategy for better utilization of the energy of therapeutic irradiation and demonstrate that subcellular targeting is a potent factor for designing nanoparticulate radiosensitizers.

A fluorescent nanobiocide based on ROS generation for eliminating pathogenic and multidrug-resistant bacteria

Exogenous reactive oxygen species (ROS) generation is a promising antibacterial strategy. The short diffusion distance coupled with the transient existence of ROS restrict their precise release at inflammation sites, so it is imperative to regulate the reactive sites of ROS donors. In this work, we developed a glycomimetic-decorated fluorescent nanobiocide to mediate the release of ROS generated from CuInS/ZnS quantum dots. The introduction of glycomimetics innovatively improved the biocompatibility of the hydrophobic quantum dots, allowing pathogenic bacteria to be targeted. The functionalized CuInS/ZnS quantum dots allowed simultaneous fluorescent reporting and sterilization under 660 nm illumination. Moreover, the nanobiocide can serve as a cell-binding glue causing bacterial aggregation, disrupting bacterial adhesion to host cells and inhibiting biofilm formation. Collectively, this work indicated the far-reaching future of ROS-generating biomimetic design for multifunctional nanobiocides to combat bacterial infections.

Graphene Oxide Nanoparticle-Loaded Ginsenoside Rg3 Improves Photodynamic Therapy in Inhibiting Malignant Progression and Stemness of Osteosarcoma

Osteosarcoma serves as a prevalent bone cancer with a high metastasis and common drug resistance, resulting in poor prognosis and high mortality. Photodynamic therapy (PDT) is a patient-specific and non-invasive tumor therapy. Nanoparticles, like graphene oxide have been widely used in drug delivery and PDT. Ginsenoside Rg3 is a principal ginseng component and has presented significant anti-cancer activities. Here, we constructed the nanoparticles using GO linked with photosensitizer (PS) indocyanine green (ICG), folic acid, and polyethylene glycol (PEG), and loaded with Rg3 (PEG–GO–FA/ICG–Rg3). We aimed to explore the effect of PEG–GO–FA/ICG–Rg3 combined with PDT for the treatment of osteosarcoma. Significantly, we found that Rg3 repressed proliferation, invasion, and migration, and enhanced apoptosis and autophagy of osteosarcoma cells, while the PEG–GO–FA/ICG–Rg3 presented a higher activity, in which NIR laser co-treatment could remarkably increase the effect of PEG–GO–FA/ICG–Rg3. Meanwhile, stemness of osteosarcoma cell–derived cancer stem cells was inhibited by Rg3 and PEG–GO–FA/ICG–Rg3, and the combination of PEG–GO–FA/ICG–Rg3 with NIR laser further significantly attenuated this phenotype in the system. Moreover, NIR laser notably improved the inhibitor effect of PEG–GO–FA/ICG–Rg3 on the tumor growth of osteosarcoma cells in vivo. Consequently, we concluded that PEG–GO–FA/ICG–Rg3 improved PDT in inhibiting malignant progression and stemness of osteosarcoma cell. Our finding provides a promising and practical therapeutic strategy for the combined treatment of osteosarcoma.

Active-targeting and acid-sensitive pluronic prodrug micelles for efficiently overcoming MDR in breast cancer

Multidrug resistance (MDR) seriously hinders therapeutic efficacy in clinical cancer treatment. Herein, we reported new polymeric prodrug micelles with tumor-targeting and acid-sensitivity properties based on two different pluronic copolymers (F127 and P123) for enhancing tumor MDR reversal and chemotherapy efficiency in breast cancer. Hybrid micelles were composed of phenylboric acid (PBA)-modified F127 (active-targeting group) and doxorubicin (DOX)-grafted P123 (prodrug groups), which were named as FBP-CAD. FBP-CAD exhibited good stability in a neutral environment and accelerated drug release under mildly acidic conditions by the cleavage of β-carboxylic amides bonds. In vitro studies demonstrated that FBP-CAD significantly increased cellular uptake and drug concentration in MCF-7/ADR cells through the homing ability of PBA and the anti-MDR effect of P123. In vivo testing further indicated that hybrid micelles facilitated drug accumulation at tumor sites as well as reduced side effects to normal organs. The synergistic effect of active-targeting and MDR-reversal leads to the highest tumor growth inhibition (TGI 78.2%). Thus, these multifunctional micelles provide a feasible approach in nanomedicine for resistant-cancer treatment.

Growing tool-kit of photosensitizers for clinical and non-clinical applications

Photosensitizers are photosensitive molecules utilized in clinical and non-clinical applications by taking advantage of light-mediated reactive oxygen generation, which triggers local and systemic cellular toxicity. Photosensitizers are used for diverse biological applications such as spatio-temporal inactivation of a protein in a living system by chromophore-assisted light inactivation, localized cell photoablation, photodynamic and immuno-photodynamic therapy, and correlative light-electron microscopy imaging. Substantial efforts have been made to develop several genetically encoded, chemically synthesized, and nanotechnologically driven photosensitizers for successful implementation in redox biology applications. Genetically encoded photosensitizers (GEPS) or reactive oxygen species (ROS) generating proteins have the advantage of using them in the living system since they can be manipulated by genetic engineering with a variety of target-specific genes for the precise spatio-temporal control of ROS generation. The GEPS variety is limited but is expanding with a variety of newly emerging GEPS proteins. Apart from GEPS, a large variety of chemically- and nanotechnologically-empowered photosensitizers have been developed with a major focus on photodynamic therapy-based cancer treatment alone or in combination with pre-existing treatment methods. Recently, immuno-photodynamic therapy has emerged as an effective cancer treatment method using smartly designed photosensitizers to initiate and engage the patient's immune system so as to empower the photosensitizing effect. In this review, we have discussed various types of photosensitizers, their clinical and non-clinical applications, and implementation toward intelligent efficacy, ROS efficiency, and target specificity in biological systems.

Photo-responsive degradable hollow mesoporous organosilica nanoplatforms for drug delivery

BACKGROUND

Stimulus-responsive degradable mesoporous organosilica nanoparticles (MONs) have shown great promise as drug carriers via enhancing the efficiency of drug delivery and accelerating the degradation of nanocarriers. However, it remains a great challenge to develop novel light-enabled spatial and temporal degradable MONs with both superior responsiveness for efficient anti-cancer drug delivery and safe exocytosis.

RESULTS

We report a novel photo-responsive degradable hollow mesoporous organosilica nanoplatform (HMONs@GOQD). The platform is based on organosilica nanoparticles (HMONs) containing singlet oxygen (¹O₂)-responsive bridged organoalkoxysilanes and wrapped graphene oxide quantum dots (GOQDs). The unique hollow mesoporous structure of the HMONs guarantees an excellent drug loading and release profile. During light irradiation, ¹O₂ produced by the GOQDs leads to the degradation of the organosilica nanoparticles, resulting in enhanced local drug release.

CONCLUSIONS

We carried out in vitro and in vivo experiments using DOX as a model drug; DOX-HMONs@GOQDs exhibited high biocompatibility, accelerated degradation, and superior therapeutic efficacy during light irradiation, indicating a promising platform for clinical cancer therapy.

Unravelling the Potential of Graphene Quantum Dots in Biomedicine and Neuroscience

Quantum dots (QDs) are semiconducting nanoparticles that have been gaining ground in various applications, including the biomedical field, thanks to their unique optical properties. Recently, graphene quantum dots (GQDs) have earned attention in biomedicine and nanomedicine, thanks to their higher biocompatibility and low cytotoxicity compared to other QDs. GQDs share the optical properties of QD and have proven ability to cross the blood-brain barrier (BBB). For this reason, GQDs are now being employed to deepen our knowledge in neuroscience diagnostics and therapeutics. Their size and surface chemistry that ease the loading of chemotherapeutic drugs, makes them ideal drug delivery systems through the bloodstream, across the BBB, up to the brain. GQDs-based neuroimaging techniques and theranostic applications, such as photothermal and photodynamic therapy alone or in combination with chemotherapy, have been designed. In this review, optical properties and biocompatibility of GQDs will be described. Then, the ability of GQDs to overtake the BBB and reach the brain will be discussed. At last, applications of GQDs in bioimaging, photophysical therapies and drug delivery to the central nervous system will be considered, unraveling their potential in the neuroscientific field.

A strategy for preparing non-fluorescent graphene oxide quantum dots as fluorescence quenchers in quantitative real-time PCR

In recent years, graphene oxide quantum dots (GOQDs) have emerged as novel nanomaterials for optical sensing, bioimaging, clinical testing, and environmental testing. However, GOQDs demonstrate unique photoluminescence properties, with GOQDs having quantum limitations and edge effects that often affect the accuracy of the test results in the sensory field. Herein, GOQDs with a large content of hydroxyl groups and low fluorescence intensity were first prepared via an improved Fenton reaction in this study, which introduces a large amount of epoxy groups to break the C-C bonds. The synthesized GOQDs show no significant variation in the fluorescence intensity upon ultraviolet and visible light excitations. We further utilized the GOQDs as fluorescence quenchers for different fluorescent dyes in real-time fluorescence quantitative polymerase chain reaction (qRT-PCR), and verified that the addition of GOQDs (5.3 μg ml-1) into a qRT-PCR system could reduce the background fluorescence intensity of the reaction by fluorescence resonance energy transfer (FRET) during its initial stage and its non-specific amplification, and improve its specificity. In addition, the qRT-PCR method could detect two different lengths of DNA sequences with a high specificity in the 104 to 1010 copies per μl range. It is of paramount importance to carry out further investigations to establish an efficient, sensitive, and specific RT-PCR method based on the use of GOQD nanomaterials as fluorescence quenchers.

Phototherapy with layered materials derived quantum dots

Quantum dots (QDs) originating from two-dimensional (2D) sheets of graphitic carbon nitride (g-C₃N₄), graphene, hexagonal boron nitride (h-BN), monoatomic buckled crystals (phosphorene), germanene, silicene and transition metal dichalcogenides (TMDCs) are emerging zero-dimensional materials. These QDs possess diverse optical properties, are chemically stable, have surprisingly excellent biocompatibility and are relatively amenable to surface modifications. It is therefore not difficult to see that these QDs have potential in a variety of bioapplications, including biosensing, bioimaging and anticancer and antimicrobial therapy. In this review, we briefly summarize the recent progress of these exciting QD based nanoagents and strategies for phototherapy. In addition, we will discuss about the current limitations, challenges and future prospects of QDs in biomedical applications.

Transcytosis of Nanomedicine for Tumor Penetration

The diffusion of nanomedicines used to treat tumors is severely hindered by the microenvironment, which is a challenge that has emerged as a bottleneck for the effective outcome of nanotherapies. Classical strategies for enhancing tumor penetration rely on passive movement in the extracellular matrix (ECM). Here, we demonstrate that nanomedicine also penetrates tumor lesions via an active trans-cell transportation process. This process was discovered by directly observing the movement of nanoparticles between cells, evaluating the intracellular trafficking pathway of nanoparticles via Rab protein labeling, comparing endocytosis-exocytosis between nanoparticles administered with inhibitors, and correlating the transcytosis process with the micro-CT distribution of nanomedicines. We also demonstrated that enhanced tumor penetration promotes the therapeutic efficacy of a photodynamic therapeutic nanomedicine. Our research thus suggests that transcytosis could be an important positive factor for designing cancer nanomedicines.

Do biomedical engineers dream of graphene sheets?

During the past few years, graphene has outstandingly emerged as a key nanomaterial for boosting the performance of commercial, industrial and scientific related technologies. The popularity of this novel nanomaterial in biomedical engineering is due to its excellent biological, electronic, optical and thermal properties that, as a whole, surpass the features of commonly used biomaterials and consequently open a wide range of applications so far within the reach of science fiction. In this minireview, the potential of graphene and its based materials in the expanding biomedical field is highlighted with focus on groundbreaking diagnostic, monitoring and therapeutic strategies. Some of the major challenges related to the synthesis and safety of graphene-based materials are also briefly discussed because of their critical importance in bringing this class of carbon materials closer to the clinic.

Photosensitizers for Photodynamic Therapy

As an emerging clinical modality for cancer treatment, photodynamic therapy (PDT) takes advantage of the cytotoxic activity of reactive oxygen species (ROS) that are generated by light irradiating photosensitizers (PSs) in the presence of oxygen (O₂ ). However, further advancements including tumor selectivity and ROS generation efficiency are still required. Substantial efforts are devoted to design and synthesize smart PSs with optimized properties for achieving a desirable therapeutic efficacy. This review summarizes the recent progress in developing intelligent PSs for efficient PDT, ranging from single molecules to delicate nanomaterials. The strategies to improve ROS generation through optimizing photoinduced electron transfer and energy transfer processes of PSs are highlighted. Moreover, the approaches that combine PDT with other therapeutics (e.g., chemotherapy, photothermal therapy, and radiotherapy) and the targeted delivery in cancer cells or tumor tissue are introduced. The main challenges for the clinical application of PSs are also discussed.

Folate-Decorated Amphiphilic Cyclodextrins as Cell-Targeted Nanophototherapeutics

Nowadays, active targeting of nanotherapeutics is a challenging issue. Here, we propose a rational design of a ternary nanoassembly (SAP) composed of nonionic amphiphilic β-cyclodextrins (amphiphilic CD) incorporating pheophorbide (Pheo) as a phototherapeutic and an adamantanyl-folic acid conjugate (Ada-FA) to target tumor cells overexpressing α-folate receptor (FR-α(+)). Dynamic light scattering and ζ-potential pointed out the presence of nanoassemblies bearing a negative surface charge (ζ = -51 mV). Morphology of SAP was investigated by atomic force microscopy and microphotoluminescence, indicating the presence of highly emissive near-spherical assemblies of about 280 nm in size. Complementary spectroscopic techniques such as ROESY-NMR, UV/vis and steady-state fluorescence revealed that the folic acid protrudes out of amphiphilic CD rims, prone for recognition with FR-α. Pheo was strongly loaded in the nanoassembly mostly in monomeric form, thus generating singlet oxygen (¹O₂) and consequentely showing phototherapeutic action. SAP remained stable until 2 weeks in aqueous solutions. Stability studies in biologically relevant media pointed out the ability of SAP to interact with serum proteins by means of the oligoethylenglycole fringe, without destabilization. Release experiments demonstrated the sustained release of Pheo from SAP in environments mimiking physiological conditions (∼20% within 1 week), plausibly suggesting low Pheo leaking and high integrity of the assembly within 24 h, time spent on average to reach the target sites. Cellular uptake of SAP was confirmed by confocal microscopy, pointing out that SAP was internalized into the tumoral cells expressing FR-α more efficiently than SP. SAP showed improved phototoxicity in human breast MCF-7 cancer cells FR-α(+) (IC₅₀ = 270 nM) with respect to human prostate carcinoma PC3 cells (IC₅₀ = 700 nM) that express a low level of that receptor (FR-α(-)). Finally, an improved phototoxicity in FR-α(+) MCF-7 cells (IC₅₀ = 270 nM) was assessed after treatment with SAP vs SP (IC₅₀ = 600 nM) which was designed without Ada-FA as a targeting unit.

A one-pot general strategy towards the synthesis of core–satellite suprastructures

A one-pot strategy developed towards the synthesis of core–satellite structures based on the fractional precipitation rule.

Graphitic carbon nitride nanosheets as a multifunctional nanoplatform for photochemical internalization-enhanced photodynamic therapy

Photodynamic therapy (PDT) has been widely used as a noninvasive and moderate technique in precision cancer therapy by destroying cancer cells via light-induced reactive oxygen species (ROS). However, the overproduction of heat shock protein 70 (HSP70) induced by ROS will contribute to the cell survival under harsh conditions, finally leading to decreased PDT efficiency. To overcome this issue, herein, for the first time, we have prepared an HSP70 inhibitor (2-phenylethynesulfonamide (PES))-loaded graphitic carbon nitride nanosheet (GCNS) as a multifunctional nanoplatform (GCNS-PES) for enhanced PDT. By taking advantage of commendable PDT efficiency, strong blue fluorescence, satisfactory drug loading capacity and good water dispersity, the GCNS can simultaneously serve as a photosensitizer, an imaging agent and a drug carrier. Moreover, when the nanoplatform is restricted in the endo/lysosome vesicles through endocytosis, the GCNS can generate ROS effectively under visible light irradiation to promote the lipid peroxidation of endo/lysosomal membranes and accelerate the liberation of GCNS and PES into the cytoplasm. Finally, the tolerance of cancer cells to ROS is decreased by PES-induced HSP70 inactivation, and therefore the efficiency of PDT is significantly enhanced. As a result, GCNS-PES can serve as a promising therapeutic nanoplatform for photo-controlled cancer therapy.