Modular Integration of Upconverting Nanocrystal–Dendrimer Composites for Folate Receptor‐Specific NIR Imaging and Light‐Triggered Drug Release

Upconversion nanocrystals (UCNs) display near‐infrared (NIR)‐responsive photoluminescent properties for NIR imaging and drug delivery. The development of effective strategies for UCN integration with other complementary nanostructures for targeting and drug conjugation is highly desirable. This study reports on a core/shell‐based theranostic system designed by UCN integration with a folate (FA)‐conjugated dendrimer for tumor targeting and with photocaged doxorubicin as a cytotoxic agent. Two types of UCNs (NaYF₄:Yb/Er (or Yb/Tm); diameter = ≈50 to 54 nm) are described, each displaying distinct emission properties upon NIR (980 nm) excitation. The UCNs are surface modified through covalent attachment of photocaged doxorubicin (ONB‐Dox) and a multivalent FA‐conjugated polyamidoamine (PAMAM) dendrimer G5(FA)₆ to prepare UCN@(ONB‐Dox)(G5FA). Surface plasmon resonance experiments performed with G5(FA)₆ dendrimer alone show nanomolar binding avidity (K_D = 5.9 × 10⁻⁹m ) to the folate binding protein. This dendrimer binding corresponds with selective binding and uptake of UCN@(ONB‐Dox)(G5FA) by FAR‐positive KB carcinoma cells in vitro. Furthermore, UCN@(ONB‐Dox)(G5FA) treatment of FAR(+) KB cells inhibits cell growth in a light dependent manner. These results validate the utility of modularly integrated UCN‐dendrimer nanocomposites for cell type specific NIR imaging and light‐controlled drug release, thus serving as a new theranostic system.     

Two‐Photon Up‐Conversion Photoluminescence Realized through Spatially Extended Gap States in Quasi‐2D Perovskite Films

A new approach to generate a two‐photon up‐conversion photoluminescence (PL) by directly exciting the gap states with continuous‐wave (CW) infrared photoexcitation in solution‐processing quasi‐2D perovskite films [(PEA)₂(MA)₄Pb₅Br₁₆ with n = 5] is reported. Specifically, a visible PL peaked at 520 nm is observed with the quadratic power dependence by exciting the gap states with CW 980 nm laser excitation, indicating a two‐photon up‐conversion PL occurring in quasi‐2D perovskite films. Decreasing the gap states by reducing the n value leads to a dramatic decrease in the two‐photon up‐conversion PL signal. This confirms that the gap states are indeed responsible for generating the two‐photon up‐conversion PL in quasi‐2D perovskites. Furthermore, mechanical scratching indicates that the different‐n‐value nanoplates are essentially uniformly formed in the quasi‐2D perovskite films toward generating multi‐photon up‐conversion light emission. More importantly, the two‐photon up‐conversion PL is found to be sensitive to an external magnetic field, indicating that the gap states are essentially formed as spatially extended states ready for multi‐photon excitation. Polarization‐dependent up‐conversion PL studies reveal that the gap states experience the orbit–orbit interaction through Coulomb polarization to form spatially extended states toward developing multi‐photon up‐conversion light emission in quasi‐2D perovskites.     

Poly(N‐phenylglycine)‐Based Nanoparticles as Highly Effective and Targeted Near‐Infrared Photothermal Therapy/Photodynamic Therapeutic Agents for Malignant Melanoma

Malignant melanoma is a highly aggressive tumor resistant to chemotherapy. Therefore, the development of new highly effective therapeutic agents for the treatment of malignant melanoma is highly desirable. In this study, a new class of polymeric photothermal agents based on poly(N‐phenylglycine) (PNPG) suitable for use in near‐infrared (NIR) phototherapy of malignant melanoma is designed and developed. PNPG is obtained via polymerization of N‐phenylglycine (NPG). Carboxylate functionality of NPG allows building multifunctional systems using covalent bonding. This approach avoids complicated issues typically associated with preparation of polymeric photothermal agents. Moreover, PNPG skeleton exhibits pH‐responsive NIR absorption and an ability to generate reactive oxygen species, which makes its derivatives attractive photothermal therapy (PTT)/photodynamic therapy (PDT) dual‐modal agents with pH‐responsive features. PNPG is modified using hyaluronic acid (HA) and polyethylene glycol diamine (PEG‐diamine) acting as the coupling agent. The resultant HA‐modified PNPG (PNPG‐PEG‐HA) shows negligible cytotoxicity and effectively targets CD44‐overexpressing cancer cells. Furthermore, the results of in vitro and in vivo experiments reveal that PNPG‐PEG‐HA selectively kills B16 cells and suppresses malignant melanoma tumor growth upon exposure to NIR light (808 nm), indicating that PNPG‐PEG‐HA can serve as a very promising nanoplatform for targeted dual‐modality PTT/PDT of melanoma.     

NIR‐II‐Excited Intravital Two‐Photon Microscopy Distinguishes Deep Cerebral and Tumor Vasculatures with an Ultrabright NIR‐I AIE Luminogen

Intravital fluorescence imaging of vasculature morphology and dynamics in the brain and in tumors with large penetration depth and high signal‐to‐background ratio (SBR) is highly desirable for the study and theranostics of vascular‐related diseases and cancers. Herein, a highly bright fluorophore (BTPETQ) with long‐wavelength absorption and aggregation‐induced near‐infrared (NIR) emission (maximum at ≈700 nm) is designed for intravital two‐photon fluorescence (2PF) imaging of a mouse brain and tumor vasculatures under NIR‐II light (1200 nm) excitation. BTPETQ dots fabricated via nanoprecipitation show uniform size of around 42 nm and a high quantum yield of 19 ± 1% in aqueous media. The 2PF imaging of the mouse brain vasculatures labeled by BTPETQ dots reveals a 3D blood vessel network with an ultradeep depth of 924 µm. In addition, BTPETQ dots show enhanced 2PF in tumor vasculatures due to their unique leaky structures, which facilitates the differentiation of normal blood vessels from tumor vessels with high SBR in deep tumor tissues. Moreover, the extravasation and accumulation of BTPETQ dots in deep tumor (more than 900 µm) is visualized under NIR‐II excitation. This study highlights the importance of developing NIR‐II light excitable efficient NIR fluorophores for in vivo deep tissue and high contrast tumor imaging.     

Near‐Infrared Excitation/Emission and Multiphoton‐Induced Fluorescence of Carbon Dots

Carbon dots (CDs) have significant potential for use in various fields including biomedicine, bioimaging, and optoelectronics. However, inefficient excitation and emission of CDs in both near‐infrared (NIR‐I and NIR‐II) windows remains an issue. Solving this problem would yield significant improvement in the tissue‐penetration depth for in vivo bioimaging with CDs. Here, an NIR absorption band and enhanced NIR fluorescence are both realized through the surface engineering of CDs, exploiting electron‐acceptor groups, namely molecules or polymers rich in sulfoxide/carbonyl groups. These groups, which are bound to the outer layers and the edges of the CDs, influence the optical bandgap and promote electron transitions under NIR excitation. NIR‐imaging information encryption and in vivo NIR fluorescence imaging of the stomach of a living mouse using CDs modified with poly(vinylpyrrolidone) in aqueous solution are demonstrated. In addition, excitation by a 1400 nm femtosecond laser yields simultaneous two‐photon‐induced NIR emission and three‐photon‐induced red emission of CDs in dimethyl sulfoxide. This study represents the realization of both NIR‐I excitation and emission as well as two‐photon‐ and three‐photon‐induced fluorescence of CDs excited in an NIR‐II window, and provides a rational design approach for construction and clinical applications of CD‐based NIR imaging agents.     

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

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

Upconversion fluorescent nanoparticles as a potential tool for in-depth imaging

Upconversion nanoparticles (UCNs) are nanoparticles that are excited in the near infrared (NIR) region with emission in the visible or NIR regions. This makes these particles attractive for use in biological imaging as the NIR light can penetrate the tissue better with minimal absorption/scattering. This paper discusses the study of the depth to which cells can be imaged using these nanoparticles. UCNs with NaYF(4) nanocrystals doped with Yb(3+), Er(3+) (visible emission)/Yb(3+), Tm(3+) (NIR emission) were synthesized and modified with silica enabling their dispersion in water and conjugation of biomolecules to their surface. The size of the sample was characterized using transmission electron microscopy and the fluorescence measured using a fluorescence spectrometer at an excitation of 980 nm. Tissue phantoms were prepared by reported methods to mimic skin/muscle tissue and it was observed that the cells could be imaged up to a depth of 3 mm using the NIR emitting UCNs. Further, the depth of detection was evaluated for UCNs targeted to gap junctions formed between cardiac cells.     

Optimization of Low‐Dimensional Components of Quasi‐2D Perovskite Films for Deep‐Blue Light‐Emitting Diodes

Compared to efficient green and near‐infrared light‐emitting diodes (LEDs), less progress has been made on deep‐blue perovskite LEDs. They suffer from inefficient domain [various number of PbX₆^? layers (n)] control, resulting in a series of unfavorable issues such as unstable color, multipeak profile, and poor fluorescence yield. Here, a strategy involving a delicate spacer modulation for quasi‐2D perovskite films via an introduction of aromatic polyamine molecules into the perovskite precursor is reported. With low‐dimensional component engineering, the n₁ domain, which shows nonradiative recombination and retarded exciton transfer, is significantly suppressed. Also, the n₃ domain, which represents the population of emission species, is remarkably increased. The optimized quasi‐2D perovskite film presents blue emission from the n₃ domain (peak at 465 nm) with a photoluminescence quantum yield (PLQY) as high as 77%. It enables the corresponding perovskite LEDs to deliver stable deep‐blue emission (CIE (0.145, 0.05)) with an external quantum efficiency (EQE) of 2.6%. The findings in this work provide further understanding on the structural and emission properties of quasi‐2D perovskites, which pave a new route to design deep‐blue‐emissive perovskite materials.     

Core–Shell–Satellite Nanomaces as Remotely Controlled Self‐Fueling Fenton Reagents for Imaging‐Guided Triple‐Negative Breast Cancer‐Specific Therapy

Triple‐negative breast cancer (TNBC) is highly aggressive and insensitive to conventional targeted therapies, resulting in poor therapeutic outcomes. Recent studies have shown that abnormal iron metabolism is observed in TNBC, suggesting an opportunity for TNBC treatment via the iron‐dependent Fenton reaction. Nevertheless, the efficiency of current Fenton reagents is largely restricted by the lack of specificity and low intracellular H₂O₂ level of cancer cells. Herein, core–shell–satellite nanomaces (Au @ MSN@IONP) are fabricated, as near‐infrared (NIR) light‐triggered self‐fueling Fenton reagents for the amplified Fenton reaction inside TNBC cells. Specifically, the Au nanorod core can convert NIR light energy into heat to induce massive production of intracellular H₂O₂, thereby the surface‐decorated iron oxide nanoparticles (IONP) are being fueled for robust Fenton reaction. By exploiting the vulnerability of iron efflux in TNBC cells, such a self‐fueling Fenton reaction leads to highly specific anti‐TNBC efficacy with minimal cytotoxicity to normal cells. The PI3K/Akt/FoxO axis, intimately involved in the redox regulation and survival of TNBC, is demonstrated to be inhibited after the treatment. Consequently, precise in vivo orthotopic TNBC ablation is achieved under the guidance of IONP‐enhanced magnetic resonance imaging. The results demonstrate the proof‐of‐concept of NIR‐light‐triggered self‐fueling Fenton reagents against TNBC with low ferroportin levels.     

Engineering of Lanthanide‐Doped Upconversion Nanoparticles for Optical Encoding

Lanthanide‐doped upconversion nanoparticles (UCNPs) are an emerging class of luminescent materials that emit UV or visible light under near infra‐red (NIR) excitations, thereby possessing a large anti‐Stokes shift property. Due to their sharp excitation and emission bands, excellent photo‐ and chemical stability, low autofluorescence, and high tissue penetration depth of the NIR light used for excitation, UCNPs have surpassed conventional fluorophores in many bioapplications. A better understanding of the mechanism of upconversion, as well as the development of better approaches to preparing UCNPs, have provided more opportunities to explore their use for optical encoding, which has the potential for applications in multiplex detection and imaging. With the current ability to precisely control the microstructure and properties of UCNPs to produce particles of tunable emission, excitation, luminescence lifetime, and size, various strategies for optical encoding based on UCNPs can now be developed. These optical properties of UCNPs (such as emission and excitation wavelengths, ratiometric intensity, luminescence lifetime, and multicolor patterns), and the strategies employed to engineer these properties for optical encoding of UCNPs through homogeneous ion doping, heterogeneous structure fabrication and microbead encapsulation are reviewed. The challenges and potential solutions faced by UCNP optical encoding are also discussed.     

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

Locating nanotherapeutics at the active sites, especially in the subcellular scale, is of great importance for nanoparticle‐based photodynamic therapy (PDT) and other nanotherapies. However, subcellular targeting agents are generally nonspecific, despite the fact that the accumulation of a nanoformulation at active organelles leads to better therapeutic efficacy. A PDT nanoformulation is herein designed by using graphene oxide quantum dots (GOQDs) with rich functional groups as both the supporter for dual targeting modification and the photosensitizer for generating reactive oxygen species, and upconversion nanoparticles (UCNs) as the transducer of excitation light. A tumor‐targeting agent, folic acid, and a mitochondrion‐targeting moiety, carboxybutyl triphenylphosphonium, are simultaneously attached onto the UCNs–GOQDs hybrid nanoparticles by surface modification, and a synergistic targeting effect is obtained for these nanoparticles according to both in vitro and in vivo experiments. More significant cell death and a higher extent of mitochondrion damage are observed compared to the results of UCNs–GOQDs nanoparticles with no or just one targeting moiety. Furthermore, the PDT efficacy on tumor‐bearing mice is also effectively improved. Overall, the current work presents a synergistic strategy to enhance subcellular targeting and the PDT efficacy for cancer therapy, which may also shed light on other kinds of nanotherapies.     

Multifunctional RbxWO3 Nanorods for Simultaneous Combined Chemo‐photothermal Therapy and Photoacoustic/CT Imaging

Light‐triggered drug delivery based on near‐infrared (NIR)‐mediated photothermal nanocarriers has received tremendous attention for the construction of cooperative therapeutic systems in nanomedicine. Herein, a new paradigm of light‐responsive drug carrier that doubles as a photothermal agent is reported based on the NIR light‐absorber, Rb _x WO₃ (rubidium tungsten bronze, Rb‐TB) nanorods. With doxorubicin (DOX) payload, the DOX‐loaded Rb‐TB composite (Rb‐TB‐DOX) simultaneously provides a burst‐like drug release and intense heating effect upon 808‐nm NIR light exposure. MTT assays show the photothermally enhanced antitumor activity of Rb‐TB‐DOX to the MCF‐7 cancer cells. Most remarkably, Rb‐TB‐DOX combined with NIR irradiation also shows dramatically enhanced chemotherapeutic effect to DOX‐resistant MCF‐7 cells compared with free DOX, demonstrating the enhanced efficacy of combinational chemo‐photothermal therapy for potentially overcoming drug resistance in cancer chemotherapy. Furthermore, in vivo study of combined chemo‐photothermal therapy is also conducted and realized on pancreatic (Pance‐1) tumor‐bearing nude mice. Apart from its promise for cancer therapy, the as‐prepared Rb‐TB can also be employed as a new dual‐modal contrast agent for photoacoustic tomography and (PAT) X‐ray computed tomography (CT) imaging because of its high NIR optical absorption capability and strong X‐ray attenuation ability, respectively. The results presented in the current study suggest promise of the multifunctional Rb _x WO₃ nanorods for applications in cancer theranostics.     

A Colloidal‐Quantum‐Dot‐Based Self‐Charging System via the Near‐Infrared Band

A novel self‐charging platform is proposed using colloidal‐quantum‐dot (CQD) photovoltaics (PVs) via the near‐infrared (NIR) band for low‐power electronics. Low‐bandgap CQDs can convert invisible NIR light sources to electrical energy more efficiently than wider spectra because of reduced thermalization loss. This energy‐conversion strategy via NIR photons ensures an enhanced photostability of the CQD devices. Furthermore, the NIR wireless charging system can be concealed using various colored and NIR‐transparent fabric or films, providing aesthetic freedom. Finally, an NIR‐driven wireless charging system is demonstrated for a wearable healthcare bracelet by integrating a CQD PVs receiver with a flexible lithium‐ion battery and entirely embedding them into a flexible strap, enabling permanent self‐charging without detachment.     

Polyaniline Nanovesicles for Photoacoustic Imaging‐Guided Photothermal‐Chemo Synergistic Therapy in the Second Near‐Infrared Window

Photoacoustic imaging‐guided photothermal therapy in the second near‐infrared (NIR‐II) window shows promise for clinical deep‐penetrating tumor phototheranostics. However, ideal photothermal agents in the NIR‐II window are still rare. Here, the emeraldine salt of polyaniline (PANI‐ES), especially synthesized by a one‐pot enzymatic reaction on sodium bis(2‐ethylhexyl) sulfosuccinate (AOT) vesicle surface (PANI‐ES@AOT, λ_max ≈ 1000 nm), exhibits excellent dispersion in physiological environment and remarkable photothermal ability at pH 6.5 (photothermal conversion efficiency of 43.9%). As a consequence of the enhanced permeability and retention effect of tumors and the doping‐induced photothermal effect of PANI‐ES@AOT, this pH‐sensitive NIR‐II photothermal agent allows tumor acidity phototheranostics with minimized pseudosignal readout and subdued normal tissue damage. Moreover, the enhanced fluidity of vesicle membrane triggered by heating is beneficial for drug release and allows precise synergistic therapy for an improved therapeutic effect. This study highlights the potential of template‐oriented (or interface‐confined) enzymatic polymerization reactions for the construction of conjugated polymers with desired biomedical applications.     

Mesoporous‐Silica‐Coated Up‐Conversion Fluorescent Nanoparticles for Photodynamic Therapy

Near‐infrared (NIR)‐to‐visible up‐conversion fluorescent nanoparticles have potential to be used for photodynamic therapy (PDT) in deep tissue because NIR light can penetrate thick tissue due to weak absorption in the optical window. Here a uniform layer of mesoporous silica is coated onto NaYF₄ up‐converting nanocrystals, with a large surface area of ≈770 m² g^?1 and an average pore size of 2 nm. A photosensitizer, zinc phthalocyanine, is incorporated into the mesoporous silica. Upon excitation by a NIR laser, the nanocrystals convert NIR light to visible light, which further activates the photosensitizer to release reactive singlet oxygen to kill cancer cells. The photosensitizer encapsulated in mesoporous silica is protected from degradation in the harsh biological environment. It is demonstrated that the photosensitizers loaded into the porous silica shell of the nanoparticles are not released out of the silica while they continuously produce singlet oxygen upon excitation by a NIR laser. The nanoparticles are reusable as the photosensitizers encapsulated in the silica are removed by soaking in ethanol.     

Near‐Infrared‐Light‐Activatable Nanomaterial‐Mediated Phototheranostic Nanomedicines: An Emerging Paradigm for Cancer Treatment

Cancer is one of the most deadly diseases threatening the lives of humans. Although many treatment methods have been developed to tackle cancer, each modality of cancer treatment has its own limitations and drawbacks. The development of minimally invasive treatment modalities for cancers remains a great challenge. Near‐infrared (NIR) light‐activated nanomaterial‐mediated phototherapies, including photothermal and photodynamic therapies, provide an alternative means for spatially and temporally controlled minimally invasive treatments of cancers. Nanomaterials can serve as nanocargoes for the delivery of chemo‐drugs, diagnostic contrast reagents, and organic photosensitizers, and can be used to directly generate heat or reactive oxygen species for the treatment of tumors without the need for organic photosensitizers with NIR‐light irradiation. Here, current progress in NIR‐light‐activated nanomaterial‐mediated photothermal therapy and photodynamic therapy is summarized. Furthermore, the effects of size, shape, and surface functionalities of nanomaterials on intracellular uptake, macrophage clearance, biodistribution, cytotoxicities, and biomedical efficacies are discussed. The use of various types of nanomaterials, such as gold nanoparticles, carbon nanotubes, graphene, and many other inorganic nanostructures, in combination with diagnostic and therapeutic modalities for solid tumors, is briefly reviewed.     

Rapid Light‐Triggered Drug Release in Liposomes Containing Small Amounts of Unsaturated and Porphyrin–Phospholipids

Prompt membrane permeabilization is a requisite for liposomes designed for local stimuli‐induced intravascular release of therapeutic payloads. Incorporation of a small amount (i.e., 5 molar percent) of an unsaturated phospholipid, such as dioleoylphosphatidylcholine (DOPC), accelerates near infrared (NIR) light‐triggered doxorubicin release in porphyrin–phospholipid (PoP) liposomes by an order of magnitude. In physiological conditions in vitro, the loaded drug can be released in a minute under NIR irradiation, while liposomes maintain serum stability otherwise. This enables rapid laser‐induced drug release using remarkably low amounts of PoP (i.e., 0.3 molar percent). Light‐triggered drug release occurs concomitantly with DOPC and cholesterol oxidation, as detected by mass spectrometry. In the presence of an oxygen scavenger or an antioxidant, light‐triggered drug release is inhibited, suggesting that the mechanism is related to singlet oxygen mediated oxidization of unsaturated lipids. Despite the irreversible modification of lipid composition, DOPC‐containing PoP liposome permeabilization is transient. Human pancreatic xenograft growth in mice is significantly delayed with a single chemophototherapy treatment following intravenous administration of 6 mg kg^?1 doxorubicin, loaded in liposomes containing small amounts of DOPC and PoP.     

Near‐Infrared Activated Black Phosphorus as a Nontoxic Photo‐Oxidant for Alzheimer's Amyloid‑β Peptide

The inhibition of amyloid‐β (Aβ) aggregation by photo‐oxygenation has become an effective way of treating Alzheimer's disease (AD). New near‐infrared (NIR) activated treatment agents, which not only possess high photo‐oxygenation efficiency, but also show low biotoxicity, are urgently needed. Herein, for the first time, it is demonstrated that NIR activated black phosphorus (BP) could serve as an effective nontoxic photo‐oxidant for amyloid?β peptide in vitro and in vivo. The nanoplatform BP@BTA (BTA: one of thioflavin‐T derivatives) possesses high affinity to the Aβ peptide due to specific amyloid selectivity of BTA. Importantly, under NIR light, BP@BTA can significantly generate a high quantum yield of singlet oxygen (¹O₂) to oxygenate Aβ, thereby resulting in inhibiting the aggregation and attenuating Aβ‐induced cytotoxicity. In addition, BP could finally degrade into nontoxic phosphate, which guarantees the biosafety. Using transgenic Caenorhabditis elegans CL2006 as AD model, the results demonstrate that the ¹O₂‐generation system could dramatically promote life‐span extension of CL2006 strain by decreasing the neurotoxicity of Aβ.     

Nanocomposite‐Based Photodynamic Therapy Strategies for Deep Tumor Treatment

Photodynamic therapy (PDT), as an emerging clinically approved modality, has been used for treatment of various cancer diseases. Conventional PDT strategies are mainly focused on superficial lesions because the wavelength of illumination light of most clinically approved photosensitizers (PSs) is located in the UV/VIS range that possesses limited tissue penetration ability, leading to ineffective therapeutic response for deep‐seated tumors. The combination of PDT and nanotechnology is becoming a promising approach to fight against deep tumors. Here, the rapid development of new PDT modalities based on various smartly designed nanocomposites integrating with conventionally used PSs for deep tumor treatments is introduced. Until now many types of multifunctional nanoparticles have been studied, and according to the source of excitation energy they can be classified into three major groups: near infrared (NIR) light excited nanomaterials, X‐ray excited scintillating/afterglow nanoparticles, and internal light emission excited nanocarriers. The in vitro and in vivo applications of these newly developed PDT modalities are further summarized here, which highlights their potential use as promising nano‐agents for deep tumor therapy.     

High Performance Quasi‐2D Perovskite Sky‐Blue Light‐Emitting Diodes Using a Dual‐Ligand Strategy

For quasi‐2D perovskite light‐emitting diodes, the introduction of insulating bulky cation reduces the charge transport property, leading to lowered brightness and increased turn‐on voltage. Herein, a dual‐ligand strategy is adopted to prepare perovskite films by using an appropriate ratio of i‐butylammonium (iBA) and phenylethylammonium (PEA) as capping ligands. The introduction of iBA enhances the binding energy of the ligands on the surface of the quasi‐2D perovskite, and effectively controls the proportion of 2D perovskite to allow more efficient energy transfer, resulting in the great enhancement of the electric and luminescent properties of the perovskite. The photoluminescence (PL) mapping of the perovskite films exhibits that enhanced photoluminescence performance with better uniformity and stronger intensity can be achieved with this dual‐ligand strategy. By adjusting the proportion of the two ligands, sky‐blue perovskite light‐emitting diodes (PeLEDs) with electroluminescence (EL) peak located 485 nm are achieved with a maximum luminance up to 1130 cd m^?2 and a maximum external quantum efficiency (EQE) up to 7.84%. In addition, the color stability and device stability are significantly enhanced by using a dual‐ligand strategy. This simple and feasible method paves the way for improving the performance of quasi‐2D PeLEDs.