Robust two-photon visualized nanocarrier with dual targeting ability for controlled chemo-photodynamic synergistic treatment of cancer

Microenvironment Restruction of Emerging 2D Materials and their Roles in Therapeutic and Diagnostic Nano-Bio-Platforms

Engineering advanced therapeutic and diagnostic nano-bio-platforms (NBPFs) have emerged as rapidly-developed pathways against a wide range of challenges in antitumor, antipathogen, tissue regeneration, bioimaging, and biosensing applications. Emerged 2D materials have attracted extensive scientific interest as fundamental building blocks or nanostructures among material scientists, chemists, biologists, and doctors due to their advantageous physicochemical and biological properties. This timely review provides a comprehensive summary of creating advanced NBPFs via emerging 2D materials (2D-NBPFs) with unique insights into the corresponding molecularly restructured microenvironments and biofunctionalities. First, it is focused on an up-to-date overview of the synthetic strategies for designing 2D-NBPFs with a cross-comparison of their advantages and disadvantages. After that, the recent key achievements are summarized in tuning the biofunctionalities of 2D-NBPFs via molecularly programmed microenvironments, including physiological stability, biocompatibility, bio-adhesiveness, specific binding to pathogens, broad-spectrum pathogen inhibitors, stimuli-responsive systems, and enzyme-mimetics. Moreover, the representative therapeutic and diagnostic applications of 2D-NBPFs are also discussed with detailed disclosure of their critical design principles and parameters. Finally, current challenges and future research directions are also discussed. Overall, this review will provide cutting-edge and multidisciplinary guidance for accelerating future developments and therapeutic/diagnostic applications of 2D-NBPFs.

Ultrathin g-C3N4 nanosheet-CoOOH nanocomposite for fluorescence imaging of ascorbic acid in living cells

Ascorbic acid (AA), a critical cellular metabolite involved in many biochemical pathways, is an important antioxidant in human body. Therefore, it is of great significance to monitor AA in living cells. Nowadays, there are various technologies developed for the detection of AA, but few methods could sensitively and selectively detect the intracellular AA. Here, we reported a highly efficient biosensor (g-C₃N₄-CoOOH nanocomposite) based on ultrathin graphitic carbon nitride (g-C₃N₄) nanosheets and CoOOH nanoflakes, for sensitive detection and fluorescence imaging of AA in living cell. The g-C₃N₄ used here as fluorescence donor is a promising bioimaging nanomaterial because of their high fluorescence quantum yield, good biocompatibility and low toxicity. In addition, the CoOOH was used to be perfect fluorescence quencher. Herein, we enabled the CoOOH in situ to form a layer on the surface of g-C₃N₄, resulting in fluorescence quench of the g-C₃N₄. Upon the addition of AA, the CoOOH nanoflakes were reduced to Co²⁺, and the system gave a "turn on" fluorescence signal. It developed as an efficient sensing platform for AA, and the linear range was from 5 to 50 μM with a 1.6 μM detection limit. This novel biosensor, g-C₃N₄-CoOOH nanocomposite exhibited highly selective response toward AA relative to other biomolecules. Furthermore, this biosensor was used successfully to visualize and monitor AA in living cells. Hopefully, we believe that this biosensor would provide a low-cost and highly sensitive platform for AA detection and bioimaging. Schematic illustration of the sensing strategy based on the g-C₃N₄-CoOOH nanocomposite for AA detection.

Two-Dimensional Ultra-Thin Nanosheets with Extraordinarily High Drug Loading and Long Blood Circulation for Cancer Therapy

Nanoparticle drug delivery is largely restricted by the low drug loading capacity of nanoparticle carriers. To address this critical challenge and maximize the potential of nanoparticle drug delivery, a 2D ultra-thin layered double hydroxide (LDH) nanosheet with exceptionally high drug loading, excellent colloidal stability, and prolonged blood circulation for cancer treatment is constructed. The nanosheet is synthesized via a biocompatible polymer-assisted bottom-up method and exhibits an ultra-thin 2D sheet-like structure that enables a considerable amount of cargo anchoring sites available for drug loading, leading to an extraordinary 734% (doxorubicin/nanoparticle mass ratio) drug loading capacity. Doxorubicin delivered by the nanosheet remains stable on the nanosheet carrier under the physiological pH condition, while showing sustained release in the tumor microenvironment and the intracellular environment, thus demonstrating on-demand drug release as a result of pH-responsive biodegradation of nanosheets. Using in vitro and in vivo 4T1 breast cancer models, the nanosheet-based ultra-high drug-loading system demonstrates even enhanced therapeutic performance compared to the multilayered LDH-based high drug-loading system, in terms of increased cellular uptake efficiency, prolonged blood circulation, superior therapeutic effect, and reduced systemic toxicity.

A near-infrared triggered upconversion/MoS2 nanoplatform for tumour-targeted chemo-photodynamic combination therapy

The combination of photodynamic therapy and chemotherapy has shown a great potential in cancer treatment. As a promising photosensitizer, MoS₂ quantum dots (QDs) have limited application due to the low tissue penetration of its light absorbing wavelength in the ultraviolet and visible regions. For the purpose of utilizing MoS₂QDs in higher NIR absorption region, herein, we constructed a core/shell nano-photosensitizer upconversion@MoS₂ with doxorubicin loading. This nanoplatform can convert 980 nm NIR into visible light, activating MoS₂QDs to produce reactive oxygen species through fluorescence resonance energy transfer. In addition, this nanoplatform presented good biocompatibility and tumor targeting after polyethylene glycol and folic acid modification. Interestingly, with pH-responsive drug release performance, this nanoplatform presented efficient chemotherapy effects. Thus, the tumour-targeted nanoplatform can achieve up-converted luminescence imaging guided chemo-photodynamic synergistic therapy effectively.

Recent advances in in situ oxygen-generating and oxygen-replenishing strategies for hypoxic-enhanced photodynamic therapy

Cancer is a leading cause of death worldwide, accounting for an estimated 10 million deaths by 2020. Over the decades, various strategies for tumor therapy have been developed and evaluated. Photodynamic therapy (PDT) has attracted increasing attention due to its unique characteristics, including low systemic toxicity and minimally invasive nature. Despite the excellent clinical promise of PDT, hypoxia is still the Achilles' heel associated with its oxygen-dependent nature related to increased tumor proliferation, angiogenesis, and distant metastases. Moreover, PDT-mediated oxygen consumption further exacerbates the hypoxia condition, which will eventually lead to the poor effect of drug treatment and resistance and irreversible tumor metastasis, even limiting its effective application in the treatment of hypoxic tumors. Hypoxia, with increased oxygen consumption, may occur in acute and chronic hypoxia conditions in developing tumors. Tumor cells farther away from the capillaries have much lower oxygen levels than cells in adjacent areas. However, it is difficult to change the tumor's deep hypoxia state through different ways to reduce the tumor tissue's oxygen consumption. Therefore, it will become more difficult to cure malignant tumors completely. In recent years, numerous investigations have focused on improving PDT therapy's efficacy by providing molecular oxygen directly or indirectly to tumor tissues. In this review, different molecular oxygen supplementation methods are summarized to alleviate tumor hypoxia from the innovative perspective of using supplemental oxygen. Besides, the existing problems, future prospects and potential challenges of this strategy are also discussed.

Carbon nitride nanomaterials with application in photothermal and photodynamic therapies

Phototherapies offer treatment of tumors with high spatial selectivity. Photodynamic therapy (PDT) consists in the administration of a photosensitizer (PS) followed by local photoirradiation with light of specific wavelength. The excited states of the PS interact with biomolecules and molecular oxygen producing reactive oxygen species (ROS), which initiate cell death. Photothermal therapy (PTT) employs photothermal agents to harvest the energy from light and convert it into heat to produce a temperature increase of the surrounding environment leading to cell death. Due to their good biocompatibility and unique photophysical properties, carbon-based materials are suitable for application in PDT and PTT. In particular, graphitic carbon nitride (g-C₃N₄), is a low-cost, non-toxic, and environment-friendly material, which is currently being used in the development of new nanomaterials with application in PDT and PTT. This brief review includes recent advances in the development of g-C₃N₄-based nanomaterials specifically designed for achieving red-shifted band gaps with the aim of generating oxygen molecules via water splitting upon red light or NIR irradiation to tackle the hypoxic condition of the tumor area. Nanomaterials designed for theranostics, combining medical imaging applications with PDT and/or PTT treatments are also included. The recent developments of g-C₃N₄-nanomaterials containing lanthanide-based upconversion nanoparticles are also covered. Finally, g-C₃N₄-based nanomaterials employed in microwave induced photodynamic therapy, sonodynamic therapy, and magnetic hyperthermia are considered.

MnO2-coated porous Pt@CeO2 core-shell nanostructures for photoacoustic imaging-guided tri-modal cancer therapy

We describe the synthesis of MnO₂-coated porous Pt@CeO₂ core-shell nanostructures (Pt@CeO₂@MnO₂) as a new theranostic nano-platform. The porous Pt cores endow the core-shell nanostructures with high photothermal conversion efficiency (80%) in the near-infrared region, allowing for photothermal therapy (PTT) and photoacoustic imaging (PA) of tumors. The combination of the Pt core and porous CeO₂ interlayer enhances the separation of photo-generated electrons and holes, which is beneficial for the generation of singlet oxygen. With the porous structures of the cores and interlayers, the Pt@CeO₂@MnO₂ nanostructures are further loaded with an anti-cancer drug (doxorubicin, DOX). The degradation of the MnO₂ shell in the tumor microenvironment (TME) can generate O₂ for enhanced photodynamic therapy (PDT) and simultaneously trigger DOX release. PA imaging shows good accumulation and retention of DOX-loaded Pt@CeO₂@MnO₂ in tumors, which guides precise laser irradiation to initiate combined PTT and PDT. The synergistic PTT/PDT/chemotherapy demonstrated by DOX-loaded Pt@CeO₂@MnO₂ yields remarkable therapeutic outcomes in vitro and in vivo. Taken together, our DOX-loaded Pt@CeO₂@MnO₂ provides a new avenue for designing high-performance nano-platforms for imaging and therapeutics.

Cell membranes targeted unimolecular prodrug for programmatic photodynamic-chemo therapy

Photodynamic therapy (PDT) has emerged as one of the most up-and-coming non-invasive therapeutic modalities for cancer therapy in rencent years. However, its therapeutic effect was still hampered by the short life span, limited diffusion distance and ineluctable depletion of singlet oxygen (1O2), as well as the hypoxic microenvironment in the tumor tissue. Such problems have limited the application of PDT and appropriate solutions are highly demand. Methods: Herein, a programmatic treatment strategy is proposed for the development of a smart molecular prodrug (D-bpy), which comprise a two-photon photosensitizer and a hypoxia-activated chemotherapeutic prodrug. A rhodamine dye was designed to connect them and track the drug release by the fluorescent signal generated through azo bond cleavage. Results: The prodrug (D-bpy) can stay on the cell membrane and enrich at the tumor site. Upon light irradiation, the therapeutic effect was enhanced by a stepwise treatment: (i) direct generation of 1O2 on the cell membrane induced membrane destruction and promoted the D-bpy uptake; (ii) deep tumor hypoxia caused by two-photon PDT process further triggered the activation of the chemotherapy prodrug. Both in vitro and in vivo experiments, D-bpy have exhabited excellent tumor treatment effect. Conclusion: The innovative programmatic treatment strategy provides new strategy for the design of follow-up anticancer drugs.

A triple-channel sensing array for protein discrimination based on multi-photoresponsive g-C3N4

Graphitic carbon nitride (g-C₃N₄) as an outstanding photoresponsive nanomaterial has been widely used in biosensing. Other than the conventional single channel sensing mode, a triple-channel sensing array was developed for high discrimination of proteins based on the photoresponsive g-C₃N₄. Besides the photoluminescence and Rayleigh light scattering features of g-C₃N₄, we exploit the new photosensitive colorimetry of g-C₃N₄ as the third channel optical input. The triple-channel optical behavior of g-C₃N₄ can be synchronously changed after interaction with the protein, resulting in the distinct response patterns related to each specific protein. Such a triple-channel sensing array is demonstrated for highly discriminative and precise identification of nine proteins (hemoglobin, trypsin, lysozyme, cytochrome c, horseradish peroxidase, transferrin, human serum albumin, pepsin, and myoglobin) at 1 μM concentration levels with 100% accuracy. It also can discriminate proteins being present at different concentration and protein mixtures with different content ratios. The practicability of this sensor array is validated by high accuracy identification of nine proteins in human urine samples. This indicates that the array has a great potential in terms of analyzing biological fluids. Graphic abstract .

Transition metal-coordinated graphitic carbon nitride dots as a sensitive and facile fluorescent probe for β-amyloid peptide detection

Herein, we developed a sensitive graphitic carbon nitride quantum dot (gCNQD)-based fluorescent strategy for β-amyloid peptide monomer (Aβ) determination down to the ng mL-1 level for the first time. To realize this goal, the nanostructured gCNQDs were firstly coordinated with four transition metal ions (Cu2+, Cu+, Fe3+, Zn2+). Our findings showed that the fluorescence (FL) intensity of gCNQDs was quenched in the presence of these metal ions possibly due to the effective chelation with the nitrogen element in gCNQDs and subsequent photoinduced electron transfer (PET) of gCNQDs. The degree of fluorescence quenching was found to be the most intense with the addition of Cu2+ and therefore, we selected Cu2+ as the quencher for the following Aβ determination. Through binding to Cu2+, the introduction of Aβ unexpectedly induced a further decline of FL intensity. Importantly, on account of different peptide sequences coexisting in the same cerebral system, including Aβ1-11, Aβ1-16, Aβ1-38, Aβ1-40 and Aβ1-42, their affinities to Cu2+ could be reflected by the distinguished declining extent of FL intensity. The possible mechanism of Aβ sensing by the probe was clarified by TEM characterization. The developed fluorescent biosensor was demonstrated to give a wide linear range from 1 to 700 ng mL-1 and a low detection limit of 0.18 ng mL-1 for Aβ1-42. In the end, the proposed fluorescence approach was successfully applied to monitoring of Aβ1-42 variations in the cortex and hippocampus of AD rats.

Physically-triggered nanosystems based on two-dimensional materials for cancer theranostics

There is an increasing demand to develop effective methods for treating malignant diseases to improve healthcare in our society. Stimuli-responsive nanosystems, which can respond to internal or external stimuli are promising in cancer therapy and diagnosis due to their functionality and versatility. As a newly emerging class of nanomaterials, two-dimensional (2D) nanomaterials have attracted huge interest in many different fields including biomedicine due to their unique physical and chemical properties. In the past decade, stimuli-responsive nanosystems based on 2D nanomaterials have been widely studied, showing promising applications in cancer therapy and diagnosis, including phototherapies, magnetic therapy, drug and gene delivery, and non-invasive imaging. Here, we will focus our attention on the state-of-the-art of physically-triggered nanosystems based on graphene and two-dimensional nanomaterials for cancer therapy and diagnosis. The physical triggers include light, temperature, magnetic and electric fields.

Specific capture and release of circulating tumor cells using a multifunctional nanofiber-integrated microfluidic chip

Aim: To develop a multifunctional nanofibrous mat-embedded microfluidic chip system for specific capture and intact release of circulating tumor cells. Materials & methods: Electrospun polyethylenimine/polyvinyl alcohol nanofibers were functionalized with zwitterions to reduce the nonspecific adhesion of blood cells, followed by modification with arginine-glycine-aspartic acid peptide via an acid-sensitive benzoic imine bond. Results: The nanofiber-embedded microchip can be applied for capturing various types of cancer cells and circulating tumor cells with high efficiency and considerable purity. The captured cancer cells can be released from the nanofibrous substrates within 30 min. Conclusion: The developed multifunctional nanofiber-embedded microfluidic chip may have a great potential for clinical applications.

Multifunctional nanocarriers based on graphitic-C3N4 quantum dots for tumor-targeted, traceable and pH-responsive drug delivery

A multifunctional nanocarrier is developed for simultaneous targeted delivery, efficient tracking and cancer treatment at the cellular level.

Photoresponsive Drug/Gene Delivery Systems

Light as an external stimulus can be precisely manipulated in terms of irradiation time, site, wavelength, and density. As such, photoresponsive drug/gene delivery systems have been increasingly pursued and utilized for the spatiotemporal control of drug/gene delivery to enhance their therapeutic efficacy and safety. In this review, we summarized the recent research progress on photoresponsive drug/gene delivery, and two major categories of delivery systems were discussed. The first category is the direct responsive systems that experience photoreactions on the vehicle or drug themselves, and different materials as well as chemical structures responsive to UV, visible, and NIR light are summarized. The second category is the indirect responsive systems that require a light-generated mediator signal, such as heat, ROS, hypoxia, and gas molecules, to cascadingly trigger the structural transformation. The future outlook and challenges are also discussed at the end.

pH-Responsive Magnetic Mesoporous Silica-Based Nanoplatform for Synergistic Photodynamic Therapy/Chemotherapy

By overcoming drug resistance and subsequently enhancing the treatment, the combination therapy of photodynamic therapy (PDT) and chemotherapy has promising potential for cancer treatment. However, the major challenge is how to establish an advanced nanoplatform that can be efficiently guided to tumor sites and can then stably release both chemotherapy drugs and a photosensitizer simultaneously and precisely. In this study, which considered the possibility and targeting efficiency of a magnetic targeting strategy, a novel Fe₃O₄@mSiO₂(DOX)@HSA(Ce6) nanoplatform was successfully built; this platform could be employed as an efficient synergistic antitumor nanoplatform with magnetic guidance for highly specific targeting and retention. Doxorubicin (DOX) molecules were loaded into mesoporous silica with high loading capability, and the mesoporous channels were blocked by a polydopamine coating. Human serum albumin (HSA) was conjugated to the outer surface to increase the biocompatibility and blood circulation time, as well as to provide a vehicle for loading photosensitizer chlorin e6 (Ce6). The sustained release of DOX under acidic conditions and the PDT induced by red light exerted a synergistic inhibitory effect on glioma cells. Our experiments demonstrated that the pH-responsive Fe₃O₄@mSiO₂(DOX)@HSA(Ce6) nanoplatform was guided to the tumor region by magnetic targeting and that the nanoplatform suppressed glioma tumor growth efficiently, implying that the system is a highly promising photodynamic therapy/chemotherapy combination nanoplatform with synergistic effects for cancer treatment.

An intelligent dual stimuli-responsive photosensitizer delivery system with O2-supplying for efficient photodynamic therapy

The effects of photodynamic therapy (PDT) are limited by the hypoxic tumor microenvironment (TME). In this paper, a new type of biocompatible multifunctional photosensitizer delivery system was fabricated to relieve tumor hypoxia and improve the efficacy of PDT. The photosensitizer hematoporphyrin monomethyl ether (HMME) and catalase (CAT) were encapsulated in the pores of mesoporous graphitic-phase carbon nitride nanosheets (mpg-C₃N₄). Next, hyaluronic (HA) was coated on the surface of the mpg-C₃N₄ via an amide linkage to construct the tumor-targeting HAase/CAT dual activatable and mpg-C₃N₄/HMME response photosensitizer delivery system (HA@mpg-C₃N₄-HMME/CAT). Upon intravenous injection, HA@mpg-C₃N₄-HMME/CAT shows high tumor accumulation owing to the tumor-targeting HA coating. Meanwhile, CAT within mpg-C₃N₄ could trigger decomposition of endogenic TME H₂O₂ to increase oxygen supply in-situ to relieve tumor hypoxia. This effect together with mpg-C₃N₄/HMME dual response is able to dramatically improve PDT efficiency. The hypoxia status of tumors was evaluated in vivo to demonstrate the success of the O₂-supplying. And the in vitro and in vivo results showed the excellent therapeutic effect of the HA@mpg-C₃N₄-HMME/CAT photosensitizer delivery system. O₂-supplying PDT may enable the enhancement of traditional PDT and future PDT design.

Recent progress in synergistic chemotherapy and phototherapy by targeted drug delivery systems for cancer treatment

Although it's pharmacological effect for cancer therapy, conventional chemotherapy has been compromised by a series of shortcomings such as limited stability, nonspecific tumour targeting ability and severe toxic side effects. To overcome these limitations, multifunctional targeted drug delivery systems for combinatorial therapeutics have been widely explored as novel cancer therapy strategies, showing encouraging results in many pre-clinical animal experiments. Among them, synergistic phototherapy and chemotherapy have demonstrated their abilities to enhance therapeutic efficacies and reduce unwanted side effects via a variety of mechanisms. In this review, we will summarize the latest progress in the development of targeted drug delivery systems with combinations of phototherapy and chemotherapy and discuss the important roles of phototherapy agents involved in those non-conventional therapeutic strategies.

Au Nanoclusters Sensitized Black TiO2-x Nanotubes for Enhanced Photodynamic Therapy Driven by Near-Infrared Light

The low reactive oxygen species production capability and the shallow tissue penetration of excited light (UV) are still two barriers in photodynamic therapy (PDT). Here, Au cluster anchored black anatase TiO_2-x nanotubes (abbreviated as Au₂₅ /B-TiO_2-x NTs) are synthesized by gaseous reduction of anatase TiO₂ NTs and subsequent deposition of noble metal. The Au₂₅ /B-TiO_2-x NTs with thickness of about 2 nm exhibit excellent PDT performance. The reduction process increased the density of Ti³⁺ on the surface of TiO₂ , which effectively depresses the recombination of electron and hole. Furthermore, after modification of Au₂₅ nanoclusters, the PDT efficiency is further enhanced owing to the changed electrical distribution in the composite, which forms a shallow potential well on the metal-TiO₂ interface to further hamper the recombination of electron and hole. Especially, the reduction of anatase TiO₂ can expend the light response range (UV) of TiO₂ to the visible and even near infrared (NIR) light region with high tissue penetration depth. When excited by NIR light, the nanoplatform shows markedly improved therapeutic efficacy attributed to the photocatalytic synergistic effect, and promotes separation or restrained recombination of electron and hole, which is verified by experimental results in vitro and in vivo.

Multifunctional Theranostics for Dual-Modal Photodynamic Synergistic Therapy via Stepwise Water Splitting

Combined therapy using multiple approaches has been demonstrated to be a promising route for cancer therapy. To achieve enhanced antiproliferation efficacy under hypoxic condition, here we report a novel hybrid system by integrating dual-model photodynamic therapies (dual-PDT) in one system. First, we attached core-shell structured up-conversion nanoparticles (UCNPs, NaGdF₄:Yb,Tm@NaGdF₄) on graphitic-phase carbon nitride (g-C₃N₄) nanosheets (one photosensitizer). Then, the as-fabricated nanocomposite and carbon dots (another photosensitizer) were assembled in ZIF-8 metal-organic frameworks through an in situ growth process, realizing the dual-photosensitizer hybrid system employed for PDT via stepwise water splitting. In this system, the UCNPs can convert deep-penetration and low-energy near-infrared light to higher-energy ultraviolet-visible emission, which matches well with the absorption range of the photosensitizers for reactive oxygen species (ROS) generation without sacrificing its efficacy under ZIF-8 shell protection. Furthermore, the UV light emitted from UCNPs allows successive activation of g-C₃N₄ and carbon dots, and the visible light from carbon dots upon UV light excitation once again activate g-C₃N₄ to produce ROS, which keeps the principle of energy conservation thus achieving maximized use of the light. This dual-PDT system exhibits excellent antitumor efficiency superior to any single modality, verified vividly by in vitro and in vivo assay.

NIR-driven water splitting by layered bismuth oxyhalide sheets for effective photodynamic therapy

Two major issues of finding the appropriate photosensitizer and raising the penetration depth of irradiation light exist in further developing of photodynamic therapy (PDT).

Graphitic Carbon Nitride Materials: Sensing, Imaging and Therapy

Graphitic carbon nitrides (g-C₃ N₄ ) are a class of 2D polymeric materials mainly composed of carbon and nitrogen atoms. g-C₃ N₄ are attracting dramatically increasing interest in the areas of sensing, imaging, and therapy, due to their unique optical and electronic properties. Here, the luminescent properties (mainly includes photoluminescence and electrochemiluminescence), and catalytic and photoelectronic properties related to sensing and therapy applications of g-C₃ N₄ materials are reviewed. Furthermore, the fabrication and advantages of sensing, imaging and therapy systems based on g-C₃ N₄ materials are summarized. Finally, the future perspectives for developing the sensing, imaging and therapy applications of the g-C₃ N₄ materials are discussed.

FeIII -Doped Two-Dimensional C3 N4 Nanofusiform: A New O2 -Evolving and Mitochondria-Targeting Photodynamic Agent for MRI and Enhanced Antitumor Therapy

Local hypoxia in tumors, as well as the short lifetime and limited action region of ¹ O₂ , are undesirable impediments for photodynamic therapy (PDT), leading to a greatly reduced effectiveness. To overcome these adversities, a mitochondria-targeting, H₂ O₂ -activatable, and O₂ -evolving PDT nanoplatform is developed based on Fe^III -doped two-dimensional C₃ N₄ nanofusiform for highly selective and efficient cancer treatment. The ultrahigh surface area of 2D nanosheets enhances the photosensitizer (PS) loading capacity and the doping of Fe^III leads to peroxidase mimetics with excellent catalytic performance towards H₂ O₂ in cancer cells to generate O₂ . As such tumor hypoxia can be overcome and the PDT efficacy is improved, whilst at the same time endowing the PDT theranostic agent with an effective T ₁ -weighted in vivo magnetic resonance imaging (MRI) ability. Conjugation with a mitochondria-targeting agent could further increase the sensitivity of cancer cells to ¹ O₂ by enhanced mitochondria dysfunction. In vitro and in vivo anticancer studies demonstrate an outstanding therapeutic effectiveness of the developed PDT agent, leading to almost complete destruction of mouse cervical tumor. This development offers an attractive theranostic agent for in vivo MRI and synergistic photodynamic therapy toward clinical applications.

Photoinduced Mild Hyperthermia and Synergistic Chemotherapy by One-Pot-Synthesized Docetaxel-Loaded Poly(lactic-co-glycolic acid)/Polypyrrole Nanocomposites

Mild hyperthermia has shown great advantages when combined with chemotherapy. The development of a multifunctional platform for the integration of mild hyperthermia capability into a drug-loading system is a key issue for cancer multimodality treatment application. Herein, a facile one-pot in situ fabrication protocol of docetaxel (DTX)-loaded poly(lactic-co-glycolic acid) (PLGA)/polypyrrole (PPy) nanocomposites was developed. While the PLGA nanoparticles (NPs) allow efficient drug loading, the PPy nanobulges embedded within the surface of the PLGA NPs, formed by in situ pyrrole polymerization without the introduction of other template agents, can act as ideal mediators for photoinduced mild hyperthermia. Physiochemical characterizations of the as-prepared nanocomposites, including structure, morphology, photothermal effects, and an in vitro drug release profile, were systematically investigated. Further, 2-deoxyglucose-terminated poly(ethylene glycol) (PEG) was anchored onto the surface of the nanocomposites to endow the nanoplatform with targeting ability to tumor cells, which resulted in a 17-fold increase of NP internalization within human breast cancer cells (MCF-7) as competed with PEG-modified nanocomposites. Mild hyperthermia can be successfully mediated by the nanoplatform, and the temperature can be conveniently controlled by careful modulation of the PPy contents within the nanocomposites or the laser power density. Importantly, we have demonstrated that MCF-7 cells, which are markedly resistant to heat treatment of traditional water-bath hyperthermia, became sensitive to the PLGA/PPy nanocomposite-mediated photothermal therapy under the same mild-temperature hyperthermia. Moreover, DTX-loaded PLGA/PPy-nanocomposite-induced mild hyperthermia can strongly enhance drug cytotoxicity to MCF-7 cells. Under the same thermal dose, photoinduced hyperthermia can convert the interaction between hyperthermia and drug treatment from interference to synergism. This is the first report on the one-pot synthesis of PLGA/PPy nanocomposites by in situ pyrrole polymerization, and such a multifunctional nanoplatform is demonstrated as a high-potential agent for photoinduced mild hyperthermia and enhanced chemotherapy.

Biomedical Uses for 2D Materials Beyond Graphene: Current Advances and Challenges Ahead

Currently, a broad interdisciplinary research effort is pursued on biomedical applications of 2D materials (2DMs) beyond graphene, due to their unique physicochemical and electronic properties. The discovery of new 2DMs is driven by the diverse chemical compositions and tuneable characteristics offered. Researchers are increasingly attracted to exploit those as drug delivery systems, highly efficient photothermal modalities, multimodal therapeutics with non-invasive diagnostic capabilities, biosensing, and tissue engineering. A crucial limitation of some of the 2DMs is their moderate colloidal stability in aqueous media. In addition, the lack of suitable functionalisation strategies should encourage the exploration of novel chemical methodologies with that purpose. Moreover, the clinical translation of these emerging materials will require undertaking of fundamental research on biocompatibility, toxicology and biopersistence in the living body as well as in the environment. Here, a thorough account of the biomedical applications using 2DMs explored today is given.

Overcoming the Achilles' heel of photodynamic therapy

This review summarizes the latest progress in deep photodynamic therapy (PDT), which overcomes the Achilles' heel of PDT.