An orthogonally regulatable DNA nanodevice for spatiotemporally controlled biorecognition and tumor treatment

Switching the NIR upconversion of nanoparticles for the orthogonal activation of photoacoustic imaging and phototherapy

Phototheranostics based on upconversion nanoparticles (UCNPs) offer the integration of imaging diagnostics and phototherapeutics. However, the programmable control of the photoactivation of imaging and therapy with minimum side effects is challenging due to the lack of ideal switchable UCNPs agents. Here we demonstrate a facile strategy to switch the near infrared emission at 800 nm from rationally designed UCNPs by modulating the irradiation laser into pulse output. We further synthesize a theranostic nanoagent by combining with a photosensitizer and a photoabsorbing agent assembled on the UCNPs. The orthogonal activation of in vivo photoacoustic imaging and photodynamic therapy can be achieved by altering the excitation modes from pulse to continuous-wave output upon a single 980 nm laser. No obvious harmful effects during photoexcitation was identified, suggesting their use for long-term imaging-guidance and phototherapy. This work provides an approach to the orthogonal activation of imaging diagnostics and photodynamic therapeutics.

Bright, Magnetic NIR-II Quantum Dot Probe for Sensitive Dual-Modality Imaging and Intensive Combination Therapy of Cancer

Improving the effectiveness of cancer therapy will require tools that enable more specific cancer targeting and improved tumor visualization. Theranostics have the potential for improving cancer care because of their ability to serve as both diagnostics and therapeutics; however, their diagnostic potential is often limited by tissue-associated light absorption and scattering. Herein, we develop CuInSe₂@ZnS:Mn quantum dots (QDs) with intrinsic multifunctionality that both enable the accurate localization of small metastases and act as potent tumor ablation agents. By leveraging the growth kinetics of a ZnS shell on a biocompatible CuInSe₂ core, Mn doping, and folic acid functionalization, we produce biocompatible QDs with high near-infrared (NIR)-II fluorescence efficiency up to 31.2%, high contrast on magnetic resonance imaging (MRI), and preferential distribution in 4T1 breast cancer tumors. MRI-enabled contrast of these nanoprobes is sufficient to timely identify small metastases in the lungs, which is critically important for preventing cancer spreading and recurrence. Further, exciting tumor-resident QDs with NIR light produces both fluorescence for tumor visualization through radiative recombination pathways as well as heat and radicals through nonradiative recombination pathways that kill cancer cells and initiate an anticancer immune response, which eliminates tumor and prevents tumor regrowth in 80% of mice.

Near-Infrared Light-Activatable Spherical Nucleic Acids for Conditional Control of Protein Activity

Optical control of protein activity represents a promising strategy for precise modulation of biological processes. We report rationally designed, aptamer-based spherical nucleic acids (SNAs) capable of noninvasive and programmable regulation of target protein activity by deep-tissue-penetrable near-infrared (NIR) light. The photoresponsive SNAs are constructed by integrating activatable aptamer modules onto the surface of upconversion nanoparticles. The SNAs remain inert but can be remotely reverted by NIR light irradiation to capture the target protein and thus function as an enzyme inhibitor, while introduction of antidote DNA could further reverse their inhibition functions. Furthermore, we demonstrate the potential of the SNAs as controllable anticoagulants for the NIR light-triggered regulation of thrombin function. Ultimately, the availability of diverse aptamers would allow the design to regulate the activities of various proteins in a programmable manner.

Tetrahedral DNA Nanostructure with Multiple Target-Recognition Domains for Ultrasensitive Electrochemical Detection of Mucin 1

In this work, a tetrahedral DNA nanostructure (TDN) designed with multiple biomolecular recognition domains (m-TDN) was assembled to construct an ultrasensitive electrochemical biosensor for the quantitative detection of tumor-associated mucin 1 (MUC-1) protein. This new nanostructure not only effectively increased the capture efficiency of target proteins compared to the traditional TDN with a single recognition domain but also enhanced the sensitivity of the constructed electrochemical biosensors. Once the target MUC-1 was captured by the protein aptamers, the ferrocene-marked DNA strands as electrochemical signal probes at the vertices of m-TDN would be released away from the electrode surface, causing significant reduction of the electrochemical signal, thereby enhancing significantly the detection sensitivity. As a result, this well-designed biosensor achieved ultrasensitive detection of the biomolecule at a linear range from 1 fg mL^-1 to 1 ng mL^-1, with the limit of detection down to 0.31 fg mL^-1. This strategy provides a new approach to enhance the detection sensitivity for the diagnosis of diseases.

Expanding the toolbox of photon upconversion for emerging frontier applications

Photon upconversion in lanthanide-based materials has recently shown compelling advantages in a wide range of fields due to their exceptional anti-Stokes luminescence performances and physicochemical properties. In particular, the latest breakthroughs in the optical manipulation of photon upconversion, such as the precise tuning of switchable emission profiles and lifetimes, open up new opportunities for diverse frontier applications from biological imaging to therapy, nanophotonics and three-dimensional displays. A summary and discussion on the recent progress can provide new insights into the fundamental understanding of luminescence mechanisms and also help to inspire new upconversion concepts and promote their frontier applications. Herein, we present a review on the state-of-the-art progress of lanthanide-based upconversion materials, focusing on the newly emerging approaches to the smart control of upconversion in aspects of light intensity, colors, and lifetimes, as well as new concepts. The emerging scientific and technological discoveries based on the well-designed upconversion materials are highlighted and discussed, along with the challenges and future perspectives. This review will contribute to the understanding of the fundamental research of photon upconversion and further promote the development of new classes of efficient upconversion materials towards diversities of frontier applications in the future.

Sandwich Fluorescence Detection of Foodborne Pathogen Staphylococcus aureus with CD Fluorescence Signal Amplification in Food Samples

Timely detection of Staphylococcus aureus (S. aureus) is critical because it can multiply to disease−causing levels in a matter of hours. Herein, a simple and sensitive DNA tetrahedral (Td) fluorescence signal amplifier with blue carbon quantum dots (bCDs) was prepared for sandwich detection of S. aureus. bCD was modified at the apex of Td, and an aptamer on Td was used to accurately identify and “adsorb” the amplifier to the surface of S. aureus. Atomic force microscopy (AFM) demonstrates the successful preparation of this signal amplifier. The fluorescence intensity emitted in this strategy increased 4.72 times. The strategy showed a stronger fluorescence intensity change, sensitivity (linear range of 7.22 × 10⁰–1.44  × 10⁹ CFU/mL with a LOD of 4 CFU/mL), and selectivity. The recovery rate in qualified pasteurized milk and drinking water samples was 96.54% to 104.72%. Compared with simple aptamer sandwich detection, these fluorescence signal amplifiers have improved fluorescence detection of S. aureus. Additionally, this fluorescent signal amplification strategy may be applied to the detection of other food pathogens or environmental microorganisms in the future.

Flash Synthesis of DNA Hydrogel via Supramacromolecular Assembly of DNA Chains and Upconversion Nanoparticles for Cell Engineering

Deoxyribonucleic acid (DNA) hydrogel has been synthesized generally via the molecular interaction of either DNA base‐pairing, covalent bonding, or physical entanglement. To surmount the limitations of DNA as the sole module in materials, new assembly modes are desired to incorporate to expand the functionalities of DNA hydrogel. Herein, a supramacromolecular assembly‐based strategy is reported to prepare a hybrid DNA hydrogel via interfacial assembly of DNA chains and upconversion nanoparticles (UCNPs), remarkably of which the synthesis process finished within one second, termed as flash synthesis. The flash synthesis is accomplished through the electrostatic attraction, interfacial assembly, and cross‐linking of DNA chains on the surface of UCNPs. The length of DNA and the crystalline form of UCNPs are proven to be essential factors in the construction of a hydrogel network. The rationally designed DNA endowed hydrogel with functions to precisely recognize and isolate specific cells, and lanthanide ions‐doped UCNPs protected cells from the damage of near‐infrared irradiation through the upconversion effect. It is envisioned that the flash synthesis provides a new mode to prepare the DNA hydrogel and expands the functionalities to realize more real‐world applications.

Controlling upconversion in emerging multilayer core-shell nanostructures: from fundamentals to frontier applications

Lanthanide-based upconversion nanomaterials have recently attracted considerable attention in both fundamental research and various frontier applications owing to their excellent photon upconversion performance and favourable physicochemical properties. In particular, the emergence of multi-layer core-shell (MLCS) nanostructures offers a versatile and powerful tool to realize well-defined matrix compositions and spatial distributions of the dopant on the nanometer length scale. In contrast to the conventional nanomaterials and commonly investigated core-shell nanoparticles, the rational design of MLCS nanostructures allows us to deliberately introduce more functional properties into an upconversion system, thus providing unprecedented opportunities for the precise manipulation of energy transfer channels, the dynamic control of upconversion processes, the fine tuning of switchable emission colours and new functional integration at a single-particle level. In this review, we present a summary and discussion on the key aspects of the recent progress in lanthanide-based MLCS nanoparticles, including the manipulation of emission and lifetime, the switchable multicolour output and the lanthanide ionic interactions on the nanoscale. Benefitting from the multifunctional and versatile luminescence properties, the MLCS nanostructures exhibit great potential in diversities of frontier applications such as three-dimensional display, upconversion laser, optical memory, anti-counterfeiting, thermometry, bioimaging, and therapy. The outlook and challenges as well as perspectives for the research in MLCS nanostructure materials are also provided. This review would be greatly helpful in exploring new structural designs of lanthanide-based materials to further manipulate the upconversion phenomenon and expand their application boundaries.

Smart Drug Delivery Systems Based on DNA Nanotechnology

The development of DNA nanotechnology has attracted tremendous attention in biotechnological and biomedical fields involving biosensing, bioimaging and disease therapy. In particular, precise control over size and shape, easy modification, excellent programmability and inherent homology make the sophisticated DNA nanostructures vital for constructing intelligent drug carriers. Recent advances in the design of multifunctional DNA-based drug delivery systems (DDSs) have demonstrated the effectiveness and advantages of DNA nanostructures, showing the unique benefits and great potential in enhancing the delivery of pharmaceutical compounds and reducing systemic toxicity. This Review aims to overview the latest researches on DNA nanotechnology-enabled nanomedicine and give a perspective on their future opportunities.

Heterostructures Made of Upconversion Nanoparticles and Metal-Organic Frameworks for Biomedical Applications

Heterostructure nanoparticles (NPs), constructed by two single-component NPs with distinct nature and multifunctional properties, have attracted intensive interest in the past few years. Among them, heterostructures made of upconversion NPs (UCNPs) and metal-organic frameworks (MOFs) can not only integrate the advantageous characteristics (e.g., porosity, structural regularity) of MOFs with unique upconverted optical features of UCNPs, but also induce cooperative properties not observed either for single component due to their special optical or electronic communications. Recently, diverse UCNP-MOF heterostructures are designed and synthesized via different strategies and have demonstrated appealing potential for applications in biosensing and imaging, drug delivery, and photodynamic therapy (PDT). In this review, the synthesis strategies of UCNP-MOF heterostructures are first summarized, then the authors focus mainly on discussion of their biomedical applications, particularly as PDT agents for cancer treatment. Finally, the authors briefly outlook the current challenges and future perspectives of UCNP-MOF hybrid nanocomposites. The authors believe that this review will provide comprehensive understanding and inspirations toward recent advances of UCNP-MOF heterostructures.

Photocaged amplified FRET nanoflares: spatiotemporal controllable of mRNA-powered nanomachines for precise and sensitive microRNA imaging in live cells

There is considerable interest in creating a precise and sensitive strategy for in situ visualizing and profiling intracellular miRNA. Present here is a novel photocaged amplified FRET nanoflare (PAFN), which spatiotemporal controls of mRNA-powered nanomachine for precise and sensitive miRNA imaging in live cells. The PAFN could be activated remotely by light, be triggered by specific low-abundance miRNA and fueled by high-abundance mRNA. It offers high spatiotemporal control over the initial activity of nanomachine at desirable time and site, and a ‘one-to-more’ ratiometric signal amplification model. The PAFN, an unprecedented design, is quiescent during the delivery process. However, upon reaching the interest tumor site, it can be selectively activated by light, and then be triggered by specific miRNA, avoiding undesirable early activation and reducing nonspecific signals, allowing precise and sensitive detection of specific miRNA in live cells. This strategy may open new avenues for creating spatiotemporally controllable and endogenous molecule-powered nanomachine, facilitating application at biological and medical imaging.

DNA Nanodevice-Based Drug Delivery Systems

DNA, a natural biological material, has become an ideal choice for biomedical applications, mainly owing to its good biocompatibility, ease of synthesis, modifiability, and especially programmability. In recent years, with the deepening of the understanding of the physical and chemical properties of DNA and the continuous advancement of DNA synthesis and modification technology, the biomedical applications based on DNA materials have been upgraded to version 2.0: through elaborate design and fabrication of smart-responsive DNA nanodevices, they can respond to external or internal physical or chemical stimuli so as to smartly perform certain specific functions. For tumor treatment, this advancement provides a new way to solve the problems of precise targeting, controllable release, and controllable elimination of drugs to a certain extent. Here, we review the progress of related fields over the past decade, and provide prospects for possible future development directions.

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.

A tyrosinase-responsive tumor-specific cascade amplification drug release system for melanoma therapy

Tumor-selective drug delivery could enhance anticancer efficacy and avoid drug side effects. However, because of tumor heterogeneity, current nanoparticle-based drug delivery systems rarely improve clinical outcomes significantly, commonly only reducing systemic toxicity. In this work, a new tumor-specific, tyrosinase-responsive cascade amplification release nanoparticle (TR-CARN) was developed to fulfill the needs for tumor-specific drug delivery and high efficacy cancer treatment. Tyrosinase (Tyr) is specifically expressed in melanomas and can catalyze acetaminophen (APAP) to increase reactive oxygen species (ROS). It was therefore utilized here to initiate the ROS amplification procedure. In TR-CARN, a ROS-responsive prodrug BDOX was loaded into an amphiphilic polymer, and APAP was linked to the polymer through a ROS-cleavable thioether bond. TR-CARN caused reduced side effects during the delivery because of the low toxicity of BDOX. Once TR-CARN entered into the tumor, endogenous ROS triggered initial APAP and BDOX release. Tyr-mediated ROS synthesis by APAP then accelerated APAP and BDOX release and toxification. Consequently, TR-CARN achieved melanoma-specific treatment of high efficacy through the cascade amplification strategy with enhanced biosafety.

DNA Nanodevices: from Mechanical Motions to Biomedical Applications

Inspired by molecular machines in nature, artificial nanodevices have been designed to realize various biomedical functions. Self-assembled deoxyribonucleic acid (DNA) nanostructures that feature designed geometries, excellent spatial accuracy, nanoscale addressability and marked biocompatibility provide an attractive candidate for constructing dynamic nanodevices with biomarker-targeting and stimuli-responsiveness for biomedical applications. Here, a summary of typical construction strategies of DNA nanodevices and their operating mechanisms are presented. We also introduced recent advances in employing DNA nanodevices as platforms for biosensing and intelligent drug delivery. Finally, the broad prospects and main challenges of the DNA nanodevices in biomedical applications are discussed.

Activating a DNA Nanomachine via Computation across Cancer Cell Membranes for Precise Therapy of Solid Tumors

Taking advantage of cancer cells' endogenous characters, the responsive activation of DNA nanomachines has achieved great success in tumor therapy. Combining with extra stimuli such as external light irradiation provided spatiotemporal control of DNA nanomachine activation. However, specific activation at the cellular level is still challenging considering the macroscopic-scale exposure area of usual light sources. DNA logic gates located at the cell membrane contributed to cellular specificity, but the free diffusion of input DNA strands during the operation process would impair efficiency and result in side effects to circumjacent normal cells in solid tumors. Here we design a transmembrane DNA logical computation strategy to activate a DNA nanomachine only in cancer cells from a complex solid tumor microenvironment. The DNA nanomachine multishell UCNPs-DNA is prepared by modifying DNA strands on upconversion nanoparticles. LA-apt, a DNA strand anchoring to a cancer cell membrane overexpressed receptor, and intracellular miRNA-21 served as inputs 1 and 2, respectively. Hybridization with input 1 at the cell membrane not only exposes the miRNA-21 recognition region at the DNA nanomachine, but also delivers it into cancer cells. The cascade hybridization with intracellular input 2 completes the "AND" gate operation and releases a DNA strand L2 as output. L2 acts as the trigger to operate the DNA nanomachine and correspondingly activates the photosensitizer Rose Bengal for reactive oxygen species generation. Through the "AND" gate operation of the DNA nanomachine across the cancer cell membrane, highly precise therapy only to cancer cells is achieved in a complex solid tumor microenvironment, which could become a promising modality for precise therapy of solid tumors.

Self-assembled micelle responsive to quick NIR light irradiation for fast drug release and highly efficient cancer therapy

Upconversion nanoparticles (UCNPs) have been used for designing near infrared (NIR) light-responsive nanocarriers and controllable drug release. However, the need for long-term NIR light irradiation over hours impaired their application efficiency. Here we develop a self-assembled micelle of amphipathic polymer P-DASA which degrades via quick NIR light irradiation. UCNPs and DOX are also encapsulated in the micelle for quick drug release. P-DASA is composed of hydrophilic polyethylene glycol segment and photo-responsive hydrophobic donor-acceptor Stenhouse adduct (DASA). Only 5-min NIR irradiation causes the hydrophilicity conversion of P-DASA and the complete disruption of micelle with DOX fast release of 83.7% in 30 min to achieve highly efficient therapy. Moreover, the P-glycoprotein mediated DOX efflux is also diminished by concomitantly producing NO intracellularly. This micelle demonstrates impressive in vivo therapeutic effect, and thus provides an avenue for highly efficient cancer therapy.

PNA-Guided Peptide Engineering of Aptamer Sensor for Protease-Unlocked Molecular Imaging

Protease-triggered control of functional DNA has remained unachieved, leaving a significant gap in activatable DNA biotechnology. Here we disclose the design of a protease-activatable aptamer technology that can perform molecular sensing and imaging function in a tumor-specific manner. The system is constructed by locking structure-switching activity of aptamer using a rationally designed PNA-peptide-PNA triblock copolymer. Highly selective cleavage of the peptide substrate is achieved by protease-mediated enzymatic reaction that result in reduced binding affinity of PNA to the aptamer module, with the subsequently recovering its biosensing function. We demonstrated that the DNA/peptide/PNA hybrid system not only allows for tumor cell-selective ATP imaging in vitro , but it also produce a fluorescent signal in vivo with improved tumor specificity. This work illustrates the potential of bridging the gap between functional DNA field and peptide area for precise biomedical applications.

Transformable upconversion metal-organic frameworks for near-infrared light-programmed chemotherapy

A transformable upconversion MOF comprising a UCNP core and an azobenzene-based MOF shell is designed for NIR light-modulated chemotherapy. The dual Förster resonance energy transfers (FRETs) involved in this delivery system trigger the transformation of the MOF for drug release and prodrug activation, thus significantly inhibiting the tumor growth and metastasis.

Site-Specific Scissors Based on Myeloperoxidase for Phosphorothioate DNA

The tool box of site-specific cleavage for nucleic acid has been an increasingly attractive subject. Especially, the recent emergence of the orthogonally activatable DNA device is closely related to the site-specific scission. However, most of these cleavage strategies are based on exogenous assistance, such as laser irradiation. Endogenous strategies are highly desirable for the orthogonally regulatable DNA machine to explore the crucial intracellular biological process and cell signal network. Here, we found that the accurate site-specific cleavage reaction of phosphorothioate (PT) modified DNA by using myeloperoxidase (MPO). A scissors-like mechanism by which MPO breaks PT modification through chloride oxidation has been revealed. Furthermore, we have successfully applied the scissors to activate PT-modified hairpin-DNA machines to produce horseradish peroxidase (HRP)-mimicking DNAzyme or initiate hybridization chain reaction (HCR) amplification. Since MPO plays an important role in the pathway related to oxidative stress in cells, through the HCR amplification activated by this tool box, the oxidative stress in living cells has been robustly imaged. This work proposes an accurate and endogenous site-specific cleavage tool for the research of biostimuli and the construction of DNA molecular devices.

Spatially Selective Imaging of Mitochondrial MicroRNAs via Optically Programmable Strand Displacement Reactions

MicroRNA (miRNA) functions are tightly regulated by their sub-compartmental location in living cells, and the ability to imaging of mitochondrial miRNAs (mitomiRs) is essential for understanding of the related pathological processes. However, most existing DNA-based methods could not be used for this purpose. Here, we report the development of a DNA nanoreporter technology for imaging of mitomiRs in living cells through near-infrared (NIR) light-controlled DNA strand displacement reactions. The sensing function of the DNA nanoreporters are silent (OFF) during the delivery process, but can be photoactivated (ON) with NIR light after targeted mitochondrial localization, enabling spatially-restricted imaging of two types of cancer-related mitomiRs with improved detection accuracy. Furthermore, we demonstrate imaging of mitomiRs in vivo through spatiotemporally-controlled delivery and activation. Therefore, this study illustrates a simple methodology that may be broadly applicable for investigating the mitomiRs-associated physiological events.

DNA Assembly-Based Stimuli-Responsive Systems

Stimuli-responsive designs with exogenous stimuli enable remote and reversible control of DNA nanostructures, which break many limitations of static nanostructures and inspired development of dynamic DNA nanotechnology. Moreover, the introduction of various types of organic molecules, polymers, chemical bonds, and chemical reactions with stimuli-responsive properties development has greatly expand the application scope of dynamic DNA nanotechnology. Here, DNA assembly-based stimuli-responsive systems are reviewed, with the focus on response units and mechanisms that depend on different exogenous stimuli (DNA strand, pH, light, temperature, electricity, metal ions, etc.), and their applications in fields of nanofabrication (DNA architectures, hybrid architectures, nanomachines, and constitutional dynamic networks) and biomedical research (biosensing, bioimaging, therapeutics, and theranostics) are discussed. Finally, the opportunities and challenges for DNA assembly-based stimuli-responsive systems are overviewed and discussed.

In Situ Protease Secretion Visualization and Metastatic Lymph Nodes Imaging via a Cell Membrane-Anchored Upconversion Nanoprobe

Matrix metalloproteinase (MMP) secretion is highly associated with tumor invasion and metastasis; therefore, monitoring MMP secretion is important for disease progression study and therapy choosing. Though working well for intracellular MMP imaging, the performance of current MMP detection probes is impaired in secretion monitoring due to the diffusion of MMP in an extracellular environment after secretion and low secreted amount. Here, we design a cell membrane-anchored ratiometric upconversion nanoprobe (UCNPs-Cy3/Pep-QSY7/Ab) for in situ MMP secretion visualization. Anti-EGFR is functionalized on the nanoprobe to provide specific recognition to tumor cells and guarantee fast response to MMP2 in the local place of secretion. MMP-responsive cleavage of Pep-QSY7 results in Cy3 luminescence recovery at 580 nm, which is ratioed over an internal standard of UCNP emission at 654 nm for MMP2 detection. The presented cell membrane-anchored ratiometric upconversion nanoprobe demonstrated that satisfactory results for in situ monitoring of MMP2 secretion from MDA-MB-231 cells and MCF-7 cells, as well as in vivo imaging of metastatic lymph nodes, would provide a universal platform for protease secretion study and contribute to tumor invasiveness assessment.

Functional Aptamer-Embedded Nanomaterials for Diagnostics and Therapeutics

In the past decades, various nanomaterials with unique properties have been explored for bioapplications. Meanwhile, aptamers, generated from the systematic evolution of ligands by exponential enrichment technology, are becoming an indispensable element in the design of functional nanomaterials because of their small size, high stability, and convenient modification, especially endowing nanomaterials with recognition capability to specific targets. Therefore, the incorporation of aptamers into nanomaterials offers an unprecedented opportunity in the research fields of diagnostics and therapeutics. Here, we focus on recent advances in aptamer-embedded nanomaterials for bioapplications. First, we briefly introduce the properties of nanomaterials that can be functionalized with aptamers. Then, the applications of aptamer-embedded nanomaterials in cellular analysis, imaging, targeted drug delivery, gene editing, and cancer diagnosis/therapy are discussed. Finally, we provide some perspectives on the challenges and opportunities that have arisen from this promising area.

Orthogonal Emissive Upconversion Nanoparticles: Material Design and Applications

Upconversion nanoparticles (UCNPs) have gone beyond traditional fluorophores in a lot of fields due to the outstanding features such as sharp excitation and emission bands, chemical and photo stability of high quality, low auto fluorescence, and high tissue permeation depth of the near-infrared irradiation light used for excitation. Conventional UCNPs carrying single/multiple emissions under a single excitation wavelength can be only employed in concurrent activation, orthogonal emissive upconversion nanoparticles (OUCNPs) with the emissions, a kind of luminescence reliant on excitation, in which by switching the external excitation different lanthanide activators can adopt independent way to control the emission, is more like an ideal UCNPs nanoplatform which can switch their activated emissions depending upon the different application for which it is used at the right time when necessary. This review summaries what has been achieved on the synthesis optimization of designed OUCNPs in recent years and sums up various applications including bioimaging, photo-switching, and programmable control process. And also, the limitations OUCNPs face, and the efforts that have been made to overcome these limitations are discussed.

Core-shell gold nanorod@mesoporous-MOF heterostructures for combinational phototherapy

Despite the increasing usage of porphyrinic metal-organic frameworks (MOFs) for combination therapy, the controlled encapsulation of inorganic nanoparticle-based therapeutics into such MOFs with specific structures has remained a major obstacle for improved tumor therapy. Here, we report the synthesis of a mesoporous MOF shell on the surface of gold nanorods (AuNRs), wherein a single AuNR is captured individually in single-crystalline MOFs with a controlled crystallographic orientation, for combinational phototherapy against solid tumors. The core-shell heterostructures have the benefits of a mesoporous structure and photoinduced singlet oxygen generation behavior characterized by the porphyrinic MOF shell, together with the plasmonic photothermal conversion characteristic of AuNRs. We demonstrated that the AuNR@MOF nanoplatform enables an efficient tumor treatment strategy by combining photodynamic therapy and photothermal therapy. We should emphasize that such systems could have applications beyond the field of cancer therapy, like plasmonic harvesting of light energy to induce and accelerate catalytic reactions within MOFs and multifunctional nanocarriers for agricultural formulations.

Target-Cell-Specific Bioorthogonal and Endogenous ATP Control of Signal Amplification for Intracellular MicroRNA Imaging

A stringent signal amplification method to profile microRNA (miRNA) expression within a specific cell remains a key challenge in biology. To address this issue, we report a target-cell-specific DNA nanosystem for endogenous adenosine-5'-triphosphate (ATP) bioorthogonal activation of the hybridization chain reaction (HCR) to spatiotemporally controlled signal amplification detection of miRNA in vitro and in vivo. The system consists of ATP aptamer-sealed engineered HCR functional units combined with a cancer cell membrane-encapsulated glutathione (GSH)-responsive metal-organic framework (MOF). Once the nanosystem is specifically and efficiently internalized into a cancer cell through membrane-mediated homing targeting, the MOF structure degrades and releases HCR functional units. The endogenous high expressional ATP recognizes the aptamer, allowing the HCR functional units to adopt its active modality. The activated HCR functional units are then able to spatiotemporally and bioorthogonally image miRNA with high sensitivity in vitro and in vivo.

DNA Nanostructures and DNA-Functionalized Nanoparticles for Cancer Theranostics

In the last two decades, DNA has attracted significant attention toward the development of materials at the nanoscale for emerging applications due to the unparalleled versatility and programmability of DNA building blocks. DNA-based artificial nanomaterials can be broadly classified into two categories: DNA nanostructures (DNA-NSs) and DNA-functionalized nanoparticles (DNA-NPs). More importantly, their use in nanotheranostics, a field that combines diagnostics with therapy via drug or gene delivery in an all-in-one platform, has been applied extensively in recent years to provide personalized cancer treatments. Conveniently, the ease of attachment of both imaging and therapeutic moieties to DNA-NSs or DNA-NPs enables high biostability, biocompatibility, and drug loading capabilities, and as a consequence, has markedly catalyzed the rapid growth of this field. This review aims to provide an overview of the recent progress of DNA-NSs and DNA-NPs as theranostic agents, the use of DNA-NSs and DNA-NPs as gene and drug delivery platforms, and a perspective on their clinical translation in the realm of oncology.

Recent Advances on Rare Earth Upconversion Nanomaterials for Combined Tumor Near-Infrared Photoimmunotherapy

Cancer has been threatening the safety of human life. In order to treat cancer, many methods have been developed to treat tumor, such as traditional therapies like surgery, chemotherapy, radiotherapy, as well as new strategies like photodynamic therapy, photothermal therapy, sonodynamic therapy, and other emerging therapies. Although there are so many ways to treat tumors, these methods all face the dilemma that they are incapable to cope with metastasis and recurrence of tumors. The emergence of immunotherapy has given the hope to conquer the challenge. Immunotherapy is to use the body's own immune system to stimulate and maintain a systemic immune response to form immunological memory, resist the metastasis and recurrence of tumors. At the same time, immunotherapy can combine with other treatments to exhibit excellent antitumor effects. Upconversion nanoparticles (UCNPs) can convert near-infrared (NIR) light into ultraviolet and visible light, thus have good performance in bioimaging and NIR triggered phototherapy. In this review paper, we summarize the design, fabrication, and application of UCNPs-based NIR photoimmunotherapy for combined cancer treatment, as well as put forward the prospect of future development.

A Near-Infrared Photo-Switched MicroRNA Amplifier for Precise Photodynamic Therapy of Early-Stage Cancers

Stimuli-responsive photodynamic therapy (PDT) is a hot topic in precise medicine, but the low abundance of responsive trigger molecules in early-stage disease limits application. Here we designed an amplifier with multiple upconversion luminances to achieve a near-infrared photo-switched cascade reaction triggered by specific microRNA and precise PDT of early-stage cancers. This amplifier was composed of photo-caged DNA nanocombs and an upconversion nanoparticle (UCNP) sensitized with IRDye 800CW. The nanocomb was prepared by assembling a photozipper-protected hairpin and two kinds of hybridizable hairpin probes on a DNA skeleton. Upon 808-nm light irradiation, the produced UV light cleaved off the photozipper to induce microRNA-responsive cascade hybridization reaction, activating the photosensitizers linked to different hairpins to generate reactive oxygen species (ROS) under the simultaneously emitted blue light for efficient PDT.