Enhanced Precision of Nanoparticle Phototargeting in Vivo at a Safe Irradiance

Triplet-Triplet Annihilation Upconversion-Based Photolysis: Applications in Photopharmacology

The emerging field of photopharmacology is a promising chemobiological methodology for optical control of drug activities that could ultimately solve the off-target toxicity outside the disease location of many drugs for the treatment of a given pathology. The use of photolytic reactions looks very attractive for a light-activated drug release but requires to develop photolytic reactions sensitive to red or near-infrared light excitation for better tissue penetration. This review will present the concepts of triplet-triplet annihilation upconversion-based photolysis and their recent in vivo applications for light-induced drug delivery using photoactivatable nanoparticles.

Structural Determinants of Stimuli-Responsiveness in Amphiphilic Macromolecular Nano-assemblies

Stimuli-responsive nano-assemblies from amphiphilic macromolecules could undergo controlled structural transformations and generate diverse macroscopic phenomenon under stimuli. Due to the controllable responsiveness, they have been applied for broad material and biomedical applications, such as biologics delivery, sensing, imaging, and catalysis. Understanding the mechanisms of the assembly-disassembly processes and structural determinants behind the responsive properties is fundamentally important for designing the next generation of nano-assemblies with programmable responsiveness. In this review, we focus on structural determinants of assemblies from amphiphilic macromolecules and their macromolecular level alterations under stimuli, such as the disruption of hydrophilic-lipophilic balance (HLB), depolymerization, decrosslinking, and changes of molecular packing in assemblies, which eventually lead to a series of macroscopic phenomenon for practical purposes. Applications of stimuli-responsive nano-assemblies in delivery, sensing and imaging were also summarized based on their structural features. We expect this review could provide readers an overview of the structural considerations in the design and applications of nanoassemblies and incentivize more explorations in stimuli-responsive soft matters.

Photochemically deoxygenating micelles for protecting TTA-UC against oxygen quenching

Pluronic F127, P123 and cross-linked F127 diacrylate micelles are photochemically deoxygenating nanocapsules in which oxygen could be removed by photochemical reaction with a surfactant and efficient triplet-triplet annihilation photon upconversion (TTA-UC) can be achieved in air. The efficiency of TTA-UC under air is comparable to that under deoxygenated conditions.

Ablation of Venous Malformations by Photothermal Therapy with Intravenous Gold Nanoshells

Venous malformations (VMs) consist of hugely enlarged and dysmorphic veins. These lesions cause significant disfigurement, pain, and complications such as bleeding and coagulopathy. Pharmacotherapy for the treatment of VMs has limited efficacy and potentially limiting toxicity. Current treatment for patients with VMs entails life-long pharmacotherapy or surgical procedures. Here we explored whether intravenously administered agents can be used to destroy VMs by photothermal therapy (PTT), using gold nanoshells (AuNSs) that generated heat following irradiation with near-infrared (NIR) light. In a murine model of VMs, intravenous AuNSs accumulated within the VMs. Irradiation of the VMs induced marked regression and even elimination. Nanoparticle-based photothermal therapy can provide effective therapy for VMs, which are otherwise relatively refractory to treatment.

Controlling the durability and optical properties of triplet-triplet annihilation upconversion nanocapsules

Deep penetration of high energy photons by direct irradiation is often not feasible due to absorption and scattering losses, which are generally exacerbated as photon energy increases. Precise generation of high energy photons beneath a surface can circumvent these losses and significantly transform optically controlled processes like photocatalysis or 3D printing. Using triplet-triplet annihilation upconversion (TTA-UC), a nonlinear process, we can locally convert two transmissive low energy photons into one high energy photon. We recently demonstrated the use of nanocapsules for high energy photon generation at depth, with durability within a variety of chemical environments due to the formation of a dense, protective silica shell that prevents content leakage and nanocapsule aggregation. Here, we show the importance of the feed concentrations of the tetraethylorthosilicate (TEOS) monomer and the methoxy poly(ethyleneglycol) silane (PEG-silane) ligand used to synthesize these nanocapsules using spectroscopic and microscopy characterizations. At optimal TEOS and PEG-silane concentrations, minimal nanocapsule leakage can be obtained which maximizes UC photoluminescence. We also spectroscopically study the origin of inefficient upconversion from UCNCs made using sub-optimal conditions to probe how TEOS and PEG-silane concentrations impact the equilibrium between productive shell growth and side product formation, like amorphous silica. Furthermore, this optimized fabrication protocol can be applied to encapsulate multiple TTA-UC systems and other emissive dyes to generate anti-Stokes or Stokes shifted emission, respectively. These results show that simple synthetic controls can be tuned to obtain robust, well-dispersed, bright upconverting nanoparticles for subsequent integration in optically controlled technologies.

Nanoengineering Triplet-Triplet Annihilation Upconversion: From Materials to Real-World Applications

Using light to control matter has captured the imagination of scientists for generations, as there is an abundance of photons at our disposal. Yet delivering photons beyond the surface to many photoresponsive systems has proven challenging, particularly at scale, due to light attenuation via absorption and scattering losses. Triplet-triplet annihilation upconversion (TTA-UC), a process which allows for low energy photons to be converted to high energy photons, is poised to overcome these challenges by allowing for precise spatial generation of high energy photons due to its nonlinear nature. With a wide range of sensitizer and annihilator motifs available for TTA-UC, many researchers seek to integrate these materials in solution or solid-state applications. In this Review, we discuss nanoengineering deployment strategies and highlight their uses in recent state-of-the-art examples of TTA-UC integrated in both solution and solid-state applications. Considering both implementation tactics and application-specific requirements, we identify critical needs to push TTA-UC-based applications from an academic curiosity to a scalable technology.

Photoresponsive prodrug‐dye nanoassembly for in‐situ monitorable cancer therapy

Photocleavable prodrugs enable controllable drug delivery to target sites modulated by light irradiation. However, the in vivo utility is usually hindered by their insolubility and inefficient delivery. In this study, we report a simple strategy of co‐assembling boron‐dipyrromethene‐chlorambucil prodrug and near‐infrared dye IR783 to fabricate photoresponsive nanoassemblies, which achieved both high prodrug loading capacity (~99%) and efficient light‐triggered prodrug activation. The incorporated IR783 dye not only stabilized the nanoparticles and contributed tumor targeting as usual, but also exhibited degradation after light irradiation and in‐situ monitoring of nanoparticle dissociation by fluorescent imaging. Systemic administration of the nanoparticles and localized light irradiation at tumor sites enabled monitorable and efficient drug release in vivo. Our results demonstrate that such prodrug‐dye co‐assembled nanomedicine is a promising formulation for photoresponsive drug delivery, which would advance the translation of photoresponsive nanomedicines.

Photocleavage-based Photoresponsive Drug Delivery

Targeted drug delivery has been extensively studied in the last decade, whereas both passive and active targeting strategies still face many challenges, such as off-target drug release. Light-responsive drug delivery systems have been developed with high controllability and spatio-temporal resolution to improve drug efficacy and reduce off-target drug release. Photoremovable protecting groups are light-responsive moieties that undergo irreversible photocleavage reactions upon light irradiation. They can be covalently linked to the molecule of interest to control its structure and function with light. In this review, we will summarize recent applications of photocleavage technologies in nanoparticle-based drug delivery for precise targeting and controlled drug release, with a highlight of strategies to achieve long-wavelength light excitation. A greater understanding of these mechanisms and emerging studies will help design more efficient photocleavage-based nanosystems to advance photoresponsive drug delivery.

Photoenhanced cytosolic protein delivery based on a photocleavable group-modified dendrimer

Numerous recently developed therapies have highlighted the advantages of using proteins as therapeutics. However, in many protein delivery systems, the complicated carrier designs, low loading content, and off-targeting effects have limited their clinical applications. Here we report a photoresponsive protein-binding moiety and use it to prepare a simple nanoscale protein delivery system with high delivery efficiency and photoenhanced cellular uptake of proteins. The carrier was prepared by modifying a photocleavable molecule, DEACM, onto the surface of a cationic dendrimer, poly(amidoamine). DEACM simultaneously contributed to protein binding, self-assembly, and photocontrollability of the system. The multi-functional DEACM enabled the simplicity of the protein delivery system, which does not require complex organic synthesis or protein modification. The high delivery efficiency, high serum tolerance, and photoenhanced cellular uptake have been proved with functional proteins, presenting the potential for delivering protein therapeutics.

Death Pathways of Cancer Cells Modulated by Surface Molecule Density on Gold Nanorods

Necrosis induces strong inflammation with undesirable implications in clinics compared with apoptosis. Fortunately, the switch between necrosis and apoptosis could be realized by tailoring the appropriate structural properties of gold nano rods (GNRs) that could precisely modulate cell death pathways. Herein, the intracellular interaction between GNRs and organelles is monitored and it is found that lysosomes dominates necrosis/apoptosis evoking. Then the surface molecule density of GNRs, which is first defined as ρsurf. molecule (Nsurf. molecules /(a × π × Diameter × Length)), mediates lysosome activities as the membrane permeabilization (LMP), the Cathepsin B and D release, the cross-talk between lysosome and different organelles, which selectively evokes apoptosis or necrosis and the production of TNF-α from macrophages. GNRs with small ρsurf. molecule mainly induce apoptosis, while with large ρsurf. molecule they greatly contribute to necrosis. Interestingly, necrosis can be suppressed by GNRs with higher ρsurf. molecule due to the overexpression of key protease caspase 8, which cleaves the RIP1-RIP3 complex and activates caspase 3 followed by necrosis to apoptosis transition. This investigation indicates that the ρsurf. molecule greatly affects the utility of nanomaterials and different structural properties of nanomaterials have different implications in clinics.

Photoresponsive PAMAM-Assembled Nanocarrier Loaded with Autophagy Inhibitor for Synergistic Cancer Therapy

As one of the most promising drug-delivery carriers due to its small size, easy surface modifiability, and hydrophobic interior, cationic poly(amidoamine) (PAMAM) per se, demonstrated by previous reports and the authors' present study, indicate potential anticancer capability, however, which are restricted by autophagy elicitation. Besides, its side-toxicity profile, having also been extensively documented, limits its translation into the clinic. Herein, the authors design a photoresponsive PAMAM-assembled nanoparticle loaded with the autophagy inhibitor (chloroquine, CQ), which exhibits light responsiveness for precisely controlling drug release and superior dark biosafety. Upon light irradiation, the nanoparticle can dissociate into charged small PAMAM for a significant antitumor effect. Meanwhile, the released CQ can inhibit pro-survival autophagy induced by PAMAM to achieve an excellent synergistic anticancer efficacy in vitro and in vivo. The authors' study provided a vision of utilizing PAMAM as self-carried anticancer therapeutics in combination with an autophagy inhibitor and proposing a cancer therapy with high antitumor efficacy and low side effects to normal tissues.

Photoactivatable Protherapeutic Nanomedicine for Cancer

Therapeutic systems with site-specific pharmaceutical activation hold great promise to enhance therapeutic efficacy while reducing systemic toxicity in cancer therapy. With operational flexibility, noninvasiveness, and high spatiotemporal resolution, photoactivatable nanomedicines have drawn growing attention. Distinct from traditional controlled release systems relying on the difference of biomarker concentrations between disease and healthy tissues, photoactivatable nanomedicines capitalize on the interaction between nanotransducers and light to either trigger photochemical reactions or generate reactive oxygen species (ROS) or heat effect to remotely induce pharmaceutical actions in living subjects. Herein, the recent advances in the development of photoactivatable protherapeutic nanoagents for oncology are summarized. The design strategies and therapeutic applications of these nanoagents are described. Representative examples of each type are discussed in terms of structure, photoactivation mechanism, and preclinical models. Last, potential challenges and perspectives to further develop photoactivatable protherapeutic nanoagents in cancer nanomedicine are discussed.

Designing Stimuli-Responsive Upconversion Nanoparticles that Exploit the Tumor Microenvironment

Tailoring personalized cancer nanomedicines demands detailed understanding of the tumor microenvironment. In recent years, smart upconversion nanoparticles with the ability to exploit the unique characteristics of the tumor microenvironment for precise targeting have been designed. To activate upconversion nanoparticles, various bio-physicochemical characteristics of the tumor microenvironment, namely, acidic pH, redox reactants, and hypoxia, are exploited. Stimuli-responsive upconversion nanoparticles also utilize the excessive presence of adenosine triphosphate (ATP), riboflavin, and Zn²⁺ in tumors. An overview of the design of stimulus-responsive upconversion nanoparticles that precisely target and respond to tumors via targeting the tumor microenvironment and intracellular signals is provided. Detailed understanding of the tumor microenvironment and the personalized design of upconversion nanoparticles will result in more effective clinical translation.

Photoreactive nanogels as versatile polymer networks with tunable in situ drug release kinetics

A simple, yet powerful approach to synthesize photoreactive nanogel networks <5 nm that can swell between ~3 and ~200 times their initial radius with control over the size and surface charge via a solution polymerization reaction protocol was demonstrated. Nanogels with hydrodynamic radii from 0.9 nm to 3.2 nm and surface charges from -6.4 mV to -16.5 mV with dramatically different abilities to swell were synthesized by altering the solvent ratio before synthesis. Additionally, the control over the release kinetics of a small molecule over a period of 30 days was demonstrated by the methacrylate functionalization of the nanogels post-synthesis and the subsequent photo-aggregation of the nanogels. Thepotential to control the release of small molecule drugs via the concentration of photoreactive groups and the photo-induced aggregation of the nanogels offers the unique ability to tailor the in situ release kinetics of the delivery network.

Endothermic and Exothermic Energy Transfer Made Equally Efficient for Triplet-Triplet Annihilation Upconversion

Expanding the anti-Stokes shift for triplet-triplet annihilation upconversion (TTA-UC) systems with high quantum yields without compromising power density thresholds (I_th) remains a critical challenge in photonics. Our studies reveal that such expansion is possible by using a highly endothermic TTA-UC pair with an enthalpy difference of +80 meV even in a polymer matrix 1000 times more viscous than toluene. Carrying out efficient endothermic triplet-triplet energy transfer (TET) requires suppression of the reverse annihilator-to-sensitizer TET, which was achieved by using sensitizers with high molar extinction coefficients and long triplet state lifetimes as well as optimized annihilator concentrations. Under these conditions, the sensitizer-to-annihilator forward TET becomes effectively entropy driven, yielding upconversion quantum yields comparable to those achieved with the exothermic TTA-UC pair but with larger anti-Stokes shifts and even lower I_th, a previously unattained achievement.

Light-Activated Nanoprobes for Biosensing and Imaging

Fluorescent nanoprobes are indispensable tools to monitor and analyze biological species and dynamic biochemical processes in cells and living bodies. Conventional nanoprobes have limitations in obtaining imaging signals with high precision and resolution because of the interference with biological autofluorescence, off-target effects, and lack of spatiotemporal control. As a newly developed paradigm, light-activated nanoprobes, whose imaging and sensing activity can be remotely regulated with light irradiation, show good potential to overcome these limitations. Herein, recent research progress on the design and construction of light-activated nanoprobes to improve bioimaging and sensing performance in complex biological systems is introduced. First, recent innovative strategies and their underlying mechanisms for light-controlled imaging are reviewed, including photoswitchable nanoprobes and phototargeted nanosystems. Subsequently, a short highlight is provided on the development of light-activatable nanoprobes for biosensing, which offer possibilities for the remote control of biorecognition and sensing activity in a precise manner both temporally and spatially. Finally, perspectives and challenges in light-activated nanoprobes are commented.

Nanoscale systems for local drug delivery

Many diseases and conditions affect a relatively localized area of the body. They can be treated either by direct deposition of drug in the target area, or by giving the drug systemically. Here we review nanoparticle-based approaches to achieving both. We highlight advantages and disadvantages that nanoscale solutions have for locally administered therapies, with emphasis on the former. We discuss strategies to enable systemically delivered nanoparticles to deliver their payloads at specific locations in the body, including triggering (local and remote) and targeting.

Designing next generation of photon upconversion: Recent advances in organic triplet-triplet annihilation upconversion nanoparticles

Organic triplet-triplet annihilation upconversion (TTA-UC) nanoparticles have emerged as exciting therapeutic agents and imaging probes in recent years due to their unique chemical and optical properties such as outstanding biocompatibility and low power excitation density. In this review, we focus on the latest breakthroughs in such new version of upconversion nanoparticle, including their design, preparation, and applications. First, we will discuss the key principles and design concept of these organic-based photon upconversion in regard to the methods of selection of the related triplet TTA dye pairs (photosensitizer and emitter). Then, we will discuss the recent approaches s to construct TTA-UCNPs including silica TTA-UCNPs, lipid-coated TTA-UCNPs, polymer encapsulated TTA-UCNPs, nano-droplet TTA-UCNPs and metal-organic frameworks (MOFs) constructed TTA-UCNPs. In addition, the applications of TTA-UCNPs will be discussed. Finally, we will discuss the challenges posed by current TTA-UCNP development.

Pulsed Microwave-Pumped Drug-Free Thermoacoustic Therapy by Highly Biocompatible and Safe Metabolic Polyarginine Probes

Serious side effects are plaguing traditional chemotherapy, and the development of drug-free treatment is expected to ease the dilemma. Herein, drug-free polyarginine probes are fabricated from the co-polymerization of arginine monomer and slight amount of rhodamine B monomer, which are efficient for thermoacoustic imaging and therapy with high biocompatibility and safe metabolism. Polyarginine can be strongly pumped upon pulsed microwave irradiation, generating significant thermoacoustic shockwaves, namely thermocavitation, which can in situ destroy mitochondria to initiate programmed cancer cell apoptosis. In vivo explorations demonstrate the high theranostic efficiency for cancer thermoacoustic imaging and cancer inhibition, exhibiting low systemic cytotoxicity and good biocompatibility after systemic administration. Herein, pulsed microwave-pumped biocompatible polyarginine is promising for drug-free precision theranostics without any detectable side effects, and the deep penetration potency of microwave makes it potentially able to treat deep-seated diseases in future biomedicine.

Intravenous treatment of choroidal neovascularization by photo-targeted nanoparticles

Choroidal neovascularization (CNV) is the major cause of vision loss in wet age-related macular degeneration (AMD). Current therapies require repeated intravitreal injections, which are painful and can cause infection, bleeding, and retinal detachment. Here we develop nanoparticles (NP-[CPP]) that can be administered intravenously and allow local drug delivery to the diseased choroid via light-triggered targeting. NP-[CPP] is formed by PEG-PLA chains modified with a cell penetrating peptide (CPP). Attachment of a DEACM photocleavable group to the CPP inhibits cellular uptake of NP-[CPP]. Irradiation with blue light cleaves DEACM from the CPP, allowing the CPP to migrate from the NP core to the surface, rendering it active. In mice with laser-induced CNV, intravenous injection of NP-[CPP] coupled to irradiation of the eye allows NP accumulation in the neovascular lesions. When loaded with doxorubicin, irradiated NP-[CPP] significantly reduces neovascular lesion size. We propose a strategy for non-invasive treatment of CNV and enhanced drug accumulation specifically in diseased areas of the eye.

Current treatments of wet age-related macular degeneration require repeated injections of active drugs into the vitreous. Here Wang et al. develop nanoparticles that when injected intravenously can be targeted to the eye by irradiation with blue light, allowing local and enhanced drug release in the back of the eye, and providing an alternative to current delivery strategies.

Study on the effectiveness of ligand reversible shielding strategy in targeted delivery and tumor therapy

We previously proved the superiority of the ligand reversible shielding strategy based on the pH-responsive self-assembly/disassembly of gold nanoparticles through computed tomography imaging in vivo. Herein, the practicality of this strategy in tumor therapy was investigated by a ligand reversible shielding system based on a temperature-responsive polymer. The ligand biotin, cisplatin-loaded chain poly(acrylic acid)-Pt, and the shielding segment thermo-sensitive poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAAm-co-AAm)) were co-modified onto the surface of gold nanostars. In the blood circulation (37 °C), the ligand was shielded by the extension of P(NIPAAm-co-AAm), whose lower critical solution temperature (LCST) is approximately 39 °C. After the nanoparticles accumulate at the tumor site by the enhanced permeability and retention (EPR) effect, the heat generated from gold nanostars upon near-infrared light irradiation would trigger the contraction of P(NIPAAm-co-AAm), thus deshielding the ligand for enhanced tumor cellular uptake. Owing to the reversible extension-contraction transformation change of P(NIPAAm-co-AAm), the reversible shielding effect on the ligand could be accomplished even if the nanoparticles return to the blood circulation. The results indicated that the system could extend blood circulation (1.6-fold at 24 h), reduce immune system clearance (28% lower), and enhance tumor accumulation (37% higher) effectively compared with the irreversible ligand shielding system by analysis of platinum. This strategy showed significantly superior tumor inhibition (11% higher) than the irreversible system. All these results make clear that the ligand reversible shielding strategy is effective and offers important references for the design of nanomaterials for improving tumor accumulation. STATEMENT OF SIGNIFICANCE: Herein, the practicality of the ligand reversible shielding strategy in tumor therapy was investigated. The ligand biotin, cisplatin loaded chain poly(acrylic acid)-Pt and the shielding segment thermo-sensitive poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAAm-co-AAm) which LCST is about 39 °C) were co-modified onto the surface of gold nanostars. This well-designed NPs could shield target ligand in blood circulation (37 °C) and deshield it at tumor site (40-41 °C) reversibly. The results indicated that the system could extend blood circulation (1.6-fold at 24 h), reduce immune system clearance (28% lower) and enhance tumor accumulation (37% higher) effectively compared with the irreversible ligand shielding system by analysis of platinum. Significantly, the strategy showed superior tumor inhibition than the irreversible system (11% higher).

ZnO-functionalized mesoporous inner-empty nanotheranostic platform: upconversion imaging guided chemotherapy with pH-triggered drug delivery

Here we report a novel drug delivery system using mesoporous inner-empty upconversion microspheres carrying drugs with ZnO quantum dots (UCMPS@ZnO) acting as a 'door-keeper' for pH-triggered drug release. Compared to other upconversion drug delivery systems, it is smarter, simpler, more efficient and more biocompatible. In particular, the UCMPS@ZnO microspheres show low cytotoxicity, are simple to produce and have a high drug loading rate (15%). Promisingly, a mice treatment experiment demonstrated that the multifunctional nanoparticles have efficient inhibition of tumor growth after a 14-day treatment. This makes UCMPS@DOX-ZnO microspheres a promising theranostic candidate in cancer treatment and clinical trials.

Development of a novel FePt-based multifunctional ferroptosis agent for high-efficiency anticancer therapy

Ferroptosis as an emerging mechanism has become a research hotspot for killing cancer cells. In this work, a novel ferroptosis agent, FePt-PTTA-Eu3+-FA (FPEF), was rationally designed by harnessing the luminescent lanthanide complexes PTTA-Eu3+ and folic acid (FA) in FePt nanoparticles. FePt-Based nanomaterials have potential applications in magnetic resonance imaging/computed tomography (MRI/CT) in clinical diagnosis and have excellent capacity to induce cancer cell death. Mechanistic studies of FPEP showed that the FePt induced cancer cell death was affirmed as the ferroptosis mechanism. To the best of our knowledge, it will be the first report that proves the existence of the ferroptosis process in FePt NPs. The in vitro tests of FPEF demonstrated that the as-prepared NPs exhibit a satisfactory anticancer effect towards FA-positive tumor cells including 4T1, MCF-7 and HeLa cells. The in vivo studies using tumor-bearing balb/c mice revealed that the FPEF NPs could significantly inhibit tumor progression. Such all-in-one therapeutic strategies have great potential in early diagnosis, prognosis and treatment of cancer.

Near Infrared Boron Dipyrromethene Nanoparticles for Optotheranostics

Boron dipyrromethene (BODIPY) is a class of important emerging fluorescent dyes. Due to their unique chemical and optical properties, near infrared (NIR)-emitting BODIPY dyes containing nanoparticles have recently been developed for a wide array of cutting-edge cancer optotheranostic applications. These nanoparticles not only have robust photostability and tunable photophysical properties, but they can also be flexibly tailored to a multitude of functional uses. Based on these outstanding characteristics, such nanoparticles have shown great promise in diagnosis as biological sensors, as well as in their utilization in advanced imaging and photomedicine for cancer treatment. In particular, here, this study first discusses their use as photoswitchable fluorescence probes toward in vitro single-molecule imaging. Second, this study takes a look at their opportunities for photoacoustic imaging utilization. Third, approaches are discussed to construct new NIR-absorbing BODIPY nanoparticles for photodynamic therapy (PDT). Fourth, this study delves into the new approach to use such nanoparticles as an emerging version of triplet-triplet annihilation upconversion (TTA-UC) and their biological uses, such as their photoactivation prodrug therapy (PAPT) for cancer. Finally, new biological sensors based on NIR BODIPY nanoparticles are introduced.

A light-triggered transmembrane porin

Porins are ideal model systems for channel engineering. Here, we present a photocaged diethylaminocoumarin (DEACM) hybrid of the transmembrane porin OmpG.

Efficient photon upconversion at remarkably low annihilator concentrations in a liquid polymer matrix: when less is more

A triplet–triplet annihilation upconversion of 24.5% was achieved at a remarkably low 600 μM annihilator concentration in a viscous polymer matrix.

Engineering the Surface of Smart Nanocarriers Using a pH-/Thermal-/GSH-Responsive Polymer Zipper for Precise Tumor Targeting Therapy In Vivo

Nanocarrier surface chemistry plays a vital role in mediating cell internalization and enhancing delivery efficiency during in vivo chemotherapy. Inspired by the ability of proteins to alter their conformation to mediate functions, a pH-/thermal-/glutathione-responsive polymer zipper consisting of cell-penetrating poly(disulfide)s and thermosensitive polymers bearing guanidinium/phosphate (Gu⁺ /pY^- ) motifs to spatiotemporally tune the surface composition of nanocarriers for precise tumor targeting and efficient drug delivery is developed. Surface engineering allows the nanocarriers to remain undetected during blood circulation and favors passive accumulation at tumor sites, where the acidic microenvironment and photothermal heating break the pY^- /Gu⁺ binding and rupture the zipper, thereby exposing the penetrating shell and causing enhanced cellular uptake via counterion-/thiol-/receptor-mediated endocytosis. The in vivo study demonstrates that by manipulating the surface states on command, the nanocarriers show longer blood circulation time, minimized uptake and drug leakage in normal organs, and enhanced accumulation and efficient drug release at tumor sites, greatly inhibiting tumor growth with only slight damage to normal tissues. If integrated with a photothermal dye approved by the U.S. Food and Drug Administration (FDA), polymer zipper would provide a versatile protocol for engineering nanomedicines with high selectivity and efficiency for clinical cancer treatment.

Carbon quantum dots with intrinsic mitochondrial targeting ability for mitochondria-based theranostics

We prepare for the first time a novel type of fluorescent carbon quantum dot (or carbon dot, CD) with intrinsic mitochondrial targeting ability by a one-step hydrothermal treatment of chitosan, ethylenediamine and mercaptosuccinic acid. The as-prepared CDs can realize mitochondrial imaging and mitochondria-targeted photodynamic cancer therapy without further modifications of other mitochondriotropic ligands (such as triphenylphosphine, TPP). Currently, many commercial mitochondrial probes suffer from the lack of modifiable groups, poor photostability, short tracking time, high cost and/or complicated staining procedures, which severely limit their applications in live-cell mitochondrial imaging. Compared to commercial mitochondrial probes such as MitoTrackers, our CDs exhibit remarkable features including ultra-simple and cost-effective synthesis, excellent photostability, facile storage, easy surface modification, wash-free and long-term imaging capability and negligible cytotoxicity. Besides, since mitochondria are susceptible to the reactive oxygen species generated during chemo-, photo- or radiotherapy, mitochondria-targeted cancer therapy has attracted much attention due to its satisfying anticancer efficiency. To test if the CDs can be used for mitochondria-targeted drug delivery, they were conjugated with a photosensitizer rose bengal (RB) and the resultant CDs-RB nanomissiles achieved efficient cellular uptake and mitochondrial targeting/accumulation, realizing mitochondria-targeted photodynamic therapy. We believe that the CD-based nanotheranostics holds great promise in various biomedical applications.

Efficient Upconversion by Highly Water-Soluble Cationic Sensitizer and Emitter in Aqueous Solutions with DNA

Highly water-soluble cationic palladium porphyrin as a sensitizer and 9,10-bis(4-trimethylammoniumphenyl)anthracene as an emitter were newly synthesized. They were shown to be bound and immobilized in DNA double helix assembly from absorption, fluorescence, phosphorescence, and circular dichroism spectra. Upon excitation at 532 nm in deaerated aqueous solutions, they showed weak blue upconversion fluorescence, the efficiency of which increased dramatically in the presence of DNA. The threshold power density between the second-order and first-order power dependence of upconversion fluorescence decreased to less than a half upon addition of DNA. The emitter triplet lifetime estimated from time dependences of upconversion fluorescence at low power ns pulsed laser was found to considerably increase in the presence of DNA. From these results, DNA was concluded to work effectively in concentrating both sensitizer and emitter and in migrating excited triplet states, resulting in efficient upconversion.

Switching Apoptosis to Ferroptosis: Metal-Organic Network for High-Efficiency Anticancer Therapy

Discovering advanced materials for regulating cell death is of great importance in the development of anticancer therapy. Herein, by harnessing the recently discovered oxidative stress regulation ability of p53 and the Fenton reaction inducing capability of metal-organic network (MON), MON encapsulated with p53 plasmid (MON-p53) was designed to eradicate cancer cells via ferroptosis/apoptosis hybrid pathway. After confirming the detailed mechanism of MON-p53 in evoking ferroptosis, we further discovered that MON-p53 mediated a "bystander effect" to further sensitize cancer cells toward the MON-p53 induced ferroptosis. A 75-day anticancer experiment indicated that MON-p53 treatment not only suppressed the tumor growth but also prolonged the life-span of tumor bearing mice. Owing to its ability to promote intracellular oxidative stress, MON-p53 decreased the blood metastasis, lung metastasis, and liver metastasis. As a consequence, discovering methods to induce cell ferroptosis would provide a new insight in designing anticancer materials.

Anti-Stokes shift luminescent materials for bio-applications

This review presents comprehensive discussions about three types of anti-Stokes luminescent materials and summarizes recent advances in their bioapplications.

A facile methodology for regulating the size of hexagonal NaYF4:Yb3+,Er3+ upconversion nanocrystals

The novelty of the work: size adjustment of hexagonal NaYF₄:Yb³⁺,Er³⁺ upconversion nanocrystals by varying only the ratio of oleic acid to rare-earth acetates.

Phototriggered Drug Delivery Using Inorganic Nanomaterials

Light has many desirable properties as the stimulus for triggerable drug delivery systems. Inorganic nanomaterials are often key components in transducing light into drug delivery events. The nature of the light and the inorganic materials can affect the efficacy and safety of the drug delivery system.