Hierarchical Plasmonic Nanorods and Upconversion Core-Satellite Nanoassemblies for Multimodal Imaging-Guided Combination Phototherapy

A Programmable DNA-Silicification-Based Nanocavity for Single-Molecule Plasmonic Sensing

Plasmonic nanocavities are highly desirable for optical sensing because of their singular ability to confine light into deep subwavelength volumes. Yet, it remains profoundly challenging to fabricate structurally resilient nanocavities with high fidelity, and to obtain direct, noninvasive visualization of the plasmonic hotspots within such constructs. Herein, highly precise and robust nanocavities, entitled DNA-silicified template for Raman optical beacon (DNA-STROBE), are engineered by using silicified DNA scaffolds for spatial organization of discrete plasmonic nanoparticles. In addition to substantially enhancing structural stability and chemical inertness, DNA silicification significantly improves nanogap control, resulting simultaneously in large and controlled local electromagnetic field enhancement. The ultrasmall mode volume of the DNA-STROBE constructs promotes single-molecule occupancy enabling surface-enhanced Raman spectroscopy (SERS) observations of single-molecule activity even at elevated background concentration, significantly relaxing the restrictive pico- to nanomolar molecular concentration condition typically required for such investigations. Additionally, leveraging super-resolution SERS measurements allows noninvasive and diffraction-unlimited spatial profiling of otherwise unresolvable plasmonic hotspots. The highly programmable and reproducible nature of the DNA-STROBE, coupled with its quantitative label-free molecular readouts, provides a versatile platform with applications across the spectrum of nanophotonics and biomedical sciences.

Nanoengineering with RAFT polymers: from nanocomposite design to applications

Reversible addition–fragmentation chain-transfer (RAFT) polymerization is a powerful tool for the precise formation of macromolecular building blocks that can be used for the construction of well-defined nanocomposites.

Light-Emitting Diode Excitation for Upconversion Microscopy: A Quantitative Assessment

Lanthanide-based upconversion nanoparticles (UCNPs) generally require high power laser excitation. Here, we report wide-field upconversion microscopy at single-nanoparticle sensitivity using incoherent excitation of a 970 nm light-emitting diode (LED). We show that due to its broad emission spectrum, LED excitation is about 3 times less effective for UCNPs and generates high background compared to laser illumination. To counter this, we use time-gated luminescence detection to eliminate the residual background from the LED source, so that individual UCNPs with high sensitizer (Yb³⁺) doping and inert shell protection become clearly identified under LED excitation at 1.18 W cm^-2, as confirmed by correlated electron microscopy images. Hydrophilic UCNPs are obtained by polysaccharide coating via a facile ligand exchange protocol to demonstrate imaging of cellular uptake using LED excitation. These results suggest a viable approach to bypassing the limitations associated with high-power lasers when applying UCNPs and upconversion microscopy to life science research.

Highly Red Light-Emitting Erbium- and Lutetium-Doped Core-Shell Upconverting Nanoparticles Surface-Modified with PEG-Folic Acid/TCPP for Suppressing Cervical Cancer HeLa Cells

Photodynamic therapy (PDT) combined with upconverting nanoparticles (UCNPs) are viewed together as an effective method of ablating tumors. After absorbing highly tissue-penetrating near-infrared (NIR) light, UCNPs emit a shorter wavelength light (~660 nm) suitable for PDT. In this study, we designed and prepared highly red fluorescence-emitting silica-coated core-shell upconverting nanoparticles modified with polyethylene glycol (PEG5k)-folic acid and tetrakis(4-carboxyphenyl)porphyrin (TCPP) (UCNPs@SiO2-NH2@FA/PEG/TCPP) as an efficient photodynamic agent for killing tumor cells. The UCNPs consisted of two simple lanthanides, erbium and lutetium, as the core and shell, respectively. The unique core-shell combination enabled the UCNPs to emit red light without green light. TCPP, folic acid, and PEG were conjugated to the outer silica layer of UCNPs as a photosensitizing agent, a ligand for tumor attachment, and a dispersing stabilizer, respectively. The prepared UCNPs of ~50 nm diameter and -34.5 mV surface potential absorbed 808 nm light and emitted ~660 nm red light. Most notably, these UCNPs were physically well dispersed and stable in the aqueous phase due to PEG attachment and were able to generate singlet oxygen (1O2) with a high efficacy. The HeLa cells were treated with each UCNP sample (0, 1, 5, 10, 20, 30 μg/mL as a free TCPP). The results showed that the combination of UCNPs@SiO2-NH2@FA/PEG/TCPP and the 808 nm laser was significantly cytotoxic to HeLa cells, almost to the same degree as naïve TCPP plus the 660 nm laser based on MTT and Live/Dead assays. Furthermore, the UCNPs@SiO2-NH2@FA/PEG/TCPP was well internalized into HeLa cells and three-dimensional HeLa spheroids, presumably due to the surface folic acid and small size in conjunction with endocytosis and the nonspecific uptake. We believe that our UCNPs@SiO2-NH2@FA/PEG/TCPP will serve as a new platform for highly efficient and deep-penetrating photodynamic agents suitable for various tumor treatments.

A pH reversibly activatable NIR photothermal/photodynamic-in-one agent integrated with renewable nanoimplants for image-guided precision phototherapy

Phototherapy has great potential to revolutionize conventional therapeutic modalities. However, most phototherapeutic strategies based on multicomponent therapeutic agents generally lack tumor-specificity, resulting in asynchronous therapy and superimposed side-effects. Severe heat damage is also inevitable because of the necessity of continuous external irradiation. Here we show the design of an acid-activated and continuous external irradiation-free photothermal and photodynamic (PTT/PDT) synchronous theranostic nanoplatform for precision tumor-targeting near-infrared (NIR) image-guided therapy. pH-reversibly responsive brominated asymmetric cyanine is designed as the tumor-specific NIR PTT/PDT-in-one agent to enhance anticancer efficiency and reduce side-effects. Ultra-small NIR persistent luminescence nanoparticles are prepared as both the imaging unit and renewable nanoimplant. Biotin functionalized polyethylene glycol is introduced to endow active tumor-targeting ability and prolong blood-circulation. The developed smart platform offers merits of reversible activation, PTT/PDT synergetic enhancement, tumor targetability and continuous external irradiation-free properties, allowing autofluorescence-free image-guided phototherapy only in tumor sites. This work paves the way to developing smart theranostic nanoplatforms for precision medicine.

Recent progress in the development of upconversion nanomaterials in bioimaging and disease treatment

Multifunctional lanthanide-based upconversion nanoparticles (UCNPs), which feature efficiently convert low-energy photons into high-energy photons, have attracted considerable attention in the domain of materials science and biomedical applications. Due to their unique photophysical properties, including light-emitting stability, excellent upconversion luminescence efficiency, low autofluorescence, and high detection sensitivity, and high penetration depth in samples, UCNPs have been widely applied in biomedical applications, such as biosensing, imaging and theranostics. In this review, we briefly introduced the major components of UCNPs and the luminescence mechanism. Then, we compared several common design synthesis strategies and presented their advantages and disadvantages. Several examples of the functionalization of UCNPs were given. Next, we detailed their biological applications in bioimaging and disease treatment, particularly drug delivery and photodynamic therapy, including antibacterial photodynamic therapy. Finally, the future practical applications in materials science and biomedical fields, as well as the remaining challenges to UCNPs application, were described. This review provides useful practical information and insights for the research on and application of UCNPs in the field of cancer.

DNA-Based Plasmonic Heterogeneous Nanostructures: Building, Optical Responses, and Bioapplications

The integration of multiple functional nanoparticles into a specific architecture allows the precise manipulation of light for coherent electron oscillations. Plasmonic metals-based heterogeneous nanostructures are fabricated by using DNA as templates. This comprehensive review provides an overview of the controllable synthesis and self-assembly of heterogeneous nanostructures, and analyzes the effects of structural parameters on the regulation of optical responses. The potential applications and challenges of heterogeneous nanostructures in the fields of biosensors and bioanalysis, in vivo monitoring, and phototheranostics are discussed.

Tumor microenvironment responsive hollow mesoporous Co9S8@MnO2-ICG/DOX intelligent nanoplatform for synergistically enhanced tumor multimodal therapy

The development of multifunctional nanoplatform with combination of tumor microenvironment (TME)-responsive dual T₁/T₂ magnetic resonance (MR) imaging and synergistically self-enhanced photothermal/photodynamic/chemo-therapy is of significant importance for tumor theranostic, which still remains a great challenge. Herein, a novel hollow mesoporous double-shell Co₉S₈@MnO₂ nanoplatform loaded with photodynamic agent of indocyanine green molecules (ICG) and chemotherapy drug of doxorubicin (DOX) was designed for TME responsive dual T₁/T₂ enhanced MR imaging and synergistically enhanced anti-tumor therapy. The designed nanoplatform with MnO₂ shell can act as a TME-responsive oxygen self-supplied producer to alleviate tumor hypoxia and simultaneously improve photodynamic therapy (PDT) efficiency. Moreover, the TME-induced MnO₂ dissolving and near-infrared (NIR) triggered photothermal nature from Co₉S₈ shell can further promote the tumor-targeted DOX release, leading to the synergistically improved anti-tumor efficacy. And the simultaneous enhancement in dual T₁/T₂ MR signal was achieved for highly specific tumor diagnosis. The in vivo and in vitro results confirmed that the designed TME-triggered nanoplatform with synergistic combination therapy presented good biocompatibility, and superior inhibition of tumor growth than monotherapy. This study provides the opportunities of designing intelligent TME-activated nanoplatform for highly specific tumor MR imaging and collaborative self-enhanced tumor therapy.

Plasmonic Modulation of the Upconversion Luminescence Based on Gold Nanorods for Designing a New Strategy of Sensing MicroRNAs

Upconversion nanoparticles (UCNPs) have potential applications in biosensing and bioimaging. However, the UCNPs-based sensors constructed by luminescence resonance energy transfer (LRET) always suffer from low quenching efficiency, hindering their application. Therefore, exploring a new strategy to resolve this issue is highly desirable. Herein, a strategy based on the surface plasmon resonance (SPR) effect of gold nanorods (AuNRs) is presented. The luminescence of UCNPs was modulated by adjusting the SiO₂ thickness of AuNRs@SiO₂ and the structure of UCNPs; an enhancement factor of ≈50 times was obtained. Based on the results of the SPR effect of AuNRs, we designed two kinds of potential upconversion microRNA sensors using microRNA-21 as a model to resolve the problem of the lower quenching efficiency resulting from a dye as a quencher. Studies revealed that the proposed strategy could be successfully used to construct upconversion microRNA sensors for avoiding the limitation of the low quenching efficiency. The sensitivity was ≈10 000 times higher than that of the upconversion sensor using dyes as quenchers. Importantly, the assay of microRNA-21 was successfully achieved using this sensor in human serum samples and human breast cancer cell (MCF-7) lysates. It provides a new method for designing upconversion microRNA sensors and may have potential for use in biosensing and bioimaging.

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 H₂ O₂ 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 H₂ O₂ , 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.

Effect of light scattering on upconversion photoluminescence quantum yield in microscale-to-nanoscale materials

Scattering affects excitation power density, penetration depth and upconversion emission self-absorption, resulting in particle size -dependent modifications of the external photoluminescence quantum yield (ePLQY) and net emission. Micron-size NaYF₄:Yb³⁺, Er³⁺ encapsulated phosphors (∼4.2 µm) showed ePLQY enhancements of >402%, with particle-media refractive index disparity (Δn): 0.4969, and net emission increases of >70%. In sub-micron phosphor encapsulants (∼406 nm), self-absorption limited ePLQY and emission as particle concentration increases, while appearing negligible in nanoparticle dispersions (∼31.8 nm). These dependencies are important for standardising PLQY measurements and optimising UC devices, since the encapsulant can drastically enhance UC emission.

Segregated Nanocompartments Containing Therapeutic Enzymes and Imaging Compounds within DNA-Zipped Polymersome Clusters for Advanced Nanotheranostic Platform

Nanotheranostics is an emerging field that brings together nanoscale-engineered materials with biological systems providing a combination of therapeutic and diagnostic strategies. However, current theranostic nanoplatforms have serious limitations, mainly due to a mismatch between the physical properties of the selected nanomaterials and their functionalization ease, loading ability, or overall compatibility with bioactive molecules. Herein, a nanotheranostic system is proposed based on nanocompartment clusters composed of two different polymersomes linked together by DNA. Careful design and procedure optimization result in clusters segregating the therapeutic enzyme human Dopa decarboxylase (DDC) and fluorescent probes for the detection unit in distinct but colocalized nanocompartments. The diagnostic compartment provides a twofold function: trackability via dye loading as the imaging component and the ability to attach the cluster construct to the surface of cells. The therapeutic compartment, loaded with active DDC, triggers the cellular expression of a secreted reporter enzyme via production of dopamine and activation of dopaminergic receptors implicated in atherosclerosis. This two-compartment nanotheranostic platform is expected to provide the basis of a new treatment strategy for atherosclerosis, to expand versatility and diversify the types of utilizable active molecules, and thus by extension expand the breadth of attainable applications.

Visible light promoted porphyrin-based metal-organic adduct

Supramolecular adducts formed by a commercial porphyrin derivative and silver nanoparticles have been obtained using exclusively light as an external trigger that is able to promote the formation of the plasmonic nanostructures. In particular, a water-soluble porphyrin, i.e. tetrakis(4-carboxyphenyl)porphyrin, has been used. It has been thoroughly characterized by means of UV-vis and fluorescence spectroscopy in order to explain its peculiar behavior when illumined with visible photons. Herein we demonstrate that, by means of light illumination, it is possible to tune the porphyrin aggregation state. Furthermore, when the monomeric form of the organic macrocycle is induced and a controlled amount of AgNO[Formula: see text] is simultaneously dissolved, it is possible to promote the formation of silver nanostructures using visible light. The proposed approach allowed porphyrin derivatives/Ag nanoparticles hybrid nanostructures to be obtained without using a chemical reducing agent: the porphyrin derivative simultaneously acts as reducing agent when irradiated by visible light and as a capping agent for the silver nanostructures. The organic/inorganic adduct was characterized by means of steady-state fluorescence that highlights a strong energetic or electronic communication between the two species. XRD and SEM investigations evidence that silver nanoparticles are formed without using any reducing agent.

Multifunctional magnetic iron oxide nanoparticles: an advanced platform for cancer theranostics

Multifunctional magnetic nanoparticles and derivative nanocomposites have aroused great concern for multimode imaging and cancer synergistic therapies in recent years. Among the rest, functional magnetic iron oxide nanoparticles (Fe3O4 NPs) have shown great potential as an advanced platform because of their inherent magnetic resonance imaging (MRI), biocatalytic activity (nanozyme), magnetic hyperthermia treatment (MHT), photo-responsive therapy and drug delivery for chemotherapy and gene therapy. Magnetic Fe3O4 NPs can be synthesized through several methods and easily surface modified with biocompatible materials or active targeting moieties. The MRI capacity could be appropriately modulated to induce response between T1 and T2 modes by controlling the size distribution of Fe3O4 NPs. Besides, small-size nanoparticles are also desired due to the enhanced permeation and retention (EPR) effect, thus the imaging and therapeutic efficiency of Fe3O4 NP-based platforms can be further improved. Here, we firstly retrospect the typical synthesis and surface modification methods of magnetic Fe3O4 NPs. Then, the latest biomedical application including responsive MRI, multimodal imaging, nanozyme, MHT, photo-responsive therapy and drug delivery, the mechanism of corresponding treatments and cooperation therapeutics of multifunctional Fe3O4 NPs are also be explained. Finally, we also outline a brief discussion and perspective on the possibility of further clinical translations of these multifunctional nanomaterials. This review would provide a comprehensive reference for readers to understand the multifunctional Fe3O4 NPs in cancer diagnosis and treatment.

DNA-Driven Nanoparticle Assemblies for Biosensing and Bioimaging

DNA molecules with superior flexibility, affinity and programmability have garnered considerable attention for the controllable assembly of nanoparticles (NPs). By controlling the density, length and sequences of DNA on NPs, the configuration of NP assemblies can be rationally designed. The specific recognition of DNA enables changes to be made to the spatial structures of NP assemblies, resulting in differences in tailorable optical signals. Comprehensive information on the fabrication of DNA-driven NP assemblies would be beneficial for their application in biosensing and bioimaging. This review analyzes the progress of DNA-driven NP assemblies, and discusses the tunable configurations determined by the structural parameters of DNA skeletons. The collective optical properties, such as chirality, fluorescence and surface enhanced Raman resonance (SERS), etc., of DNA-driven NP assemblies are explored, and engineered tailorable optical properties of these spatial structures are achieved. We discuss the development of DNA-directed NP assemblies for the quantification of DNA, toxins, and heavy metal ions, and demonstrate their potential application in the biosensing and bioimaging of tumor markers, RNA, living metal ions and phototherapeutics. We hihghlight possible challenges in the development of DNA-driven NP assemblies, and further direct potential prospects in the practical applications of macroscopical materials and photonic devices.

Advances in nanomaterials for photodynamic therapy applications: Status and challenges

Photodynamic therapy (PDT), as a non-invasive therapeutic modality that is alternative to radiotherapy and chemotherapy, is extensively investigated for cancer treatments. Although conventional organic photosensitizers (PSs) are still widely used and have achieved great progresses in PDT, the disadvantages such as hydrophobicity, poor stability within PDT environment and low cell/tissue specificity largely limit their clinical applications. Consequently, nano-agents with promising physicochemical and optical properties have emerged as an attractive alternative to overcome these drawbacks of traditional PSs. Herein, the up-to-date advances in the fabrication and fascinating applications of various nanomaterials in PDT have been summarized, including various types of nanoparticles, carbon-based nanomaterials, and two-dimensional nanomaterials, etc. In addition, the current challenges for the clinical use of PDT, and the corresponding strategies to address these issues, as well as future perspectives on further improvement of PDT have also been discussed.

Stereospecific interactions between chiral inorganic nanomaterials and biological systems

Chirality is ubiquitous in nature and plays mysterious and essential roles in maintaining key biological and physiological processes.

Theranostic nanobubble encapsulating a plasmon-enhanced upconversion hybrid nanosystem for cancer therapy

Nanobubble (NB), which simultaneously enhances ultrasound (US) images and access therapeutic platforms, is required for future cancer treatment. Methods: We designed a theranostic agent for novel cancer treatment by using an NB-encapsulated hybrid nanosystem that can be monitored by US and fluorescent imaging and activated by near-infrared (NIR) light. The nanosystem was transported to the tumor through the enhanced permeability and retention effect. The hybrid nanosystem comprised upconversion nanoparticle (UCNP) and mesoporous silica-coated gold nanorod (AuNR@mS) with the photosensitizer merocyanine 540 to realize dual phototherapy. Results: With the NIR light-triggered, the luminous intensity of the UCNP was enhanced by doping holmium ion and emitted visible green and red lights at 540 and 660 nm. The high optical density state between the UCNP and AuNR@mS can induce plasmonic enhancement to improve the photothermal and photodynamic effects, resulting in cell death by apoptosis. The nanosystem showed excellent stability to avoid the aggregation of nanoparticles during the treatment. JC-1 dye was used as an indicator of mitochondrial membrane potential to identify the mechanism of cell death. The results of in vitro and in vivo analyses confirmed the curative effect of improved dual phototherapy. Conclusion: We developed and showed the therapeutic functions of a novel nanosystem with the combination of multiple theranostic nanoplatforms that can be triggered and activated by 808 nm NIR laser and US.

"All-in-One" Theranostic Agent with Seven Functions Based on Bi-Doped Metal Chalcogenide Nanoflowers

Most of the existing single-component nanostructures cannot provide comprehensive diagnostic information, and their treatment strategies always have to combine other therapeutics as a complementary for effective biomedical application. Here, we adopted a facile approach to design a theranostic nanoflower (NF) with robust efficacy for comprehensive tumor diagnosis and quadruple synergistic cancer therapy. The NF is equipped with a metallic hybrid of several functional elements and flower-like superstructures and thus shows excellent in vitro and in vivo theranostic performance. It shows high X-ray attenuation coefficiency for the Bi element, strong near-infrared (NIR) plasmon absorbance and singlet oxygen (¹O₂) generation ability for the Mo element, and great photothermal conversion efficiency (54.7%) because of enhanced photoabsorption of the petal structure. Moreover, the NF realizes a very high doxorubicin-loading efficiency (90.0%) and bimodal pH/NIR-responsive drug release, posing a promise as a controlled drug carrier. The NF also shows excellent performance at trimodal magnetic resonance/X-ray computed tomography/photoacoustic imaging for comprehensive tumor diagnosis. To our best knowledge, it is the first time that integrating at least seven functions into one biomedical nanomaterial for well-rounded tumor theranostics has been reported. This "all-in-one" NF opens a new perspective in developing novel and efficient multifunctional nanotheranostics.

Multicomponent Plasmonic Nanoparticles: From Heterostructured Nanoparticles to Colloidal Composite Nanostructures

Plasmonic nanostructures possessing unique and versatile optoelectronic properties have been vastly investigated over the past decade. However, the full potential of plasmonic nanostructure has not yet been fully exploited, particularly with single-component homogeneous structures with monotonic properties, and the addition of new components for making multicomponent nanoparticles may lead to new-yet-unexpected or improved properties. Here we define the term "multi-component nanoparticles" as hybrid structures composed of two or more condensed nanoscale domains with distinctive material compositions, shapes, or sizes. We reviewed and discussed the designing principles and synthetic strategies to efficiently combine multiple components to form hybrid nanoparticles with a new or improved plasmonic functionality. In particular, it has been quite challenging to precisely synthesize widely diverse multicomponent plasmonic structures, limiting realization of the full potential of plasmonic heterostructures. To address this challenge, several synthetic approaches have been reported to form a variety of different multicomponent plasmonic nanoparticles, mainly based on heterogeneous nucleation, atomic replacements, adsorption on supports, and biomolecule-mediated assemblies. In addition, the unique and synergistic features of multicomponent plasmonic nanoparticles, such as combination of pristine material properties, finely tuned plasmon resonance and coupling, enhanced light-matter interactions, geometry-induced polarization, and plasmon-induced energy and charge transfer across the heterointerface, were reported. In this review, we comprehensively summarize the latest advances on state-of-art synthetic strategies, unique properties, and promising applications of multicomponent plasmonic nanoparticles. These plasmonic nanoparticles including heterostructured nanoparticles and composite nanostructures are prepared by direct synthesis and physical force- or biomolecule-mediated assembly, which hold tremendous potential for plasmon-mediated energy transfer, magnetic plasmonics, metamolecules, and nanobiotechnology.

Plasmonic Pt Superstructures with Boosted Near-Infrared Absorption and Photothermal Conversion Efficiency in the Second Biowindow for Cancer Therapy

Photothermal therapy triggered by near-infrared light in the second biowindow (NIR-II) has attracted extensive interest owing to its deeper penetration depth of biological tissue, lower photon scattering, and higher maximum permissible exposure. In spite of noble metals showing great potential as the photothermal agents due to the tunable localized surface plasmon resonance, the biological applications of platinum are rarely explored. Herein, a monocomponent hollow Pt nanoframe ("Pt Spirals"), whose superstructure is assembled with three levels (3D frame, 2D layered shells, and 1D nanowires), is reported. Pt Spirals exhibit outstanding photothermal conversion efficiency (52.5%) and molar extinction coefficients (228.7 m² mol^-1 ) in NIR-II, which are much higher than those of solid Pt cubes. Simulations indicate that the unique superstructure can be a significant cause for improving both adsorption and the photothermal effect simultaneously in NIR-II. The excellent photothermal effect is achieved and subsequently verified in in vitro and in vivo experiments, along with superb heat-resistance properties, excellent photostability, and a prominent effect on computed tomography (CT) imaging, demonstrating that Pt Spirals are promising as effective theranostic platforms for CT imaging-guided photothermal therapy.

A Dual-Model Imaging Theragnostic System Based on Mesoporous Silica Nanoparticles for Enhanced Cancer Phototherapy

Mesoporous silica nanoparticles (MSNs) show great promise to be exploited as versatile multifunctional nanocarriers for effective cancer diagnosis and treatment. In this work, perfluorohexane (PFH)-encapsulated MSNs with indocyanine green (ICG)-polydopamine (PDA) layer and poly(ethylene glycol)-folic acid coating (designated as MSNs-PFH@PDA-ICG-PEG-FA) are successfully fabricated to achieve tumor ultrasonic (US)/near-infrared fluorescence (NIRF) imaging as well as photothermal therapy (PTT)/photodynamic therapy (PDT). MSNs-PFH@PDA-ICG-PEG-FA exhibits good monodispersity with high ICG loading, significantly enhances ICG photostability, and greatly improves cellular uptake. Upon single 808 nm NIR irradiation, the nanocarrier not only efficiently generates hyperthermia to realize PTT, but also produces reactive oxygen species (ROS) for effective PDT. Meanwhile, NIR irradiation can trigger PFH to undergo vaporization and provide a super-resolution US image. Thus, the PTT/PDT combination therapy can be dually guided by PFH-induced US imaging and ICG-induced NIRF imaging. In vivo antitumor studies demonstrate that PTT/PDT from MSNs-PFH@PDA-ICG-PEG-FA significantly inhibits tumor growth and achieves a cure rate of 60% (three out of five mice are completely cured). Hence, the multifunctional MSNs appear to be a promising theragnostic nanoplatform for multimodal cancer imaging and therapy.

Plasmonic Photothermal Nanoparticles for Biomedical Applications

Recent advances of plasmonic nanoparticles include fascinating developments in the fields of energy, catalyst chemistry, optics, biotechnology, and medicine. The plasmonic photothermal properties of metallic nanoparticles are of enormous interest in biomedical fields because of their strong and tunable optical response and the capability to manipulate the photothermal effect by an external light source. To date, most biomedical applications using photothermal nanoparticles have focused on photothermal therapy; however, to fully realize the potential of these particles for clinical and other applications, the fundamental properties of photothermal nanoparticles need to be better understood and controlled, and the photothermal effect-based diagnosis, treatment, and theranostics should be thoroughly explored. This Progress Report summarizes recent advances in the understanding and applications of plasmonic photothermal nanoparticles, particularly for sensing, imaging, therapy, and drug delivery, and discusses the future directions of these fields.

Facile Phototherapeutic Nanoplatform by Integrating a Multifunctional Polymer and MnO2 for Enhancing Tumor Synergistic Therapy

Recent studies indicate that the synergistic phototherapy (SPT) process can simultaneously generate heat for photothermal therapy (PTT) and singlet oxygen (¹ O₂ ) for photodynamic therapy (PDT) to overcome the recurrence of tumors. However, the hypoxic environment in tumors seriously limits the therapeutic effect of the oxygen-dependent PDT, leading to the domination of PTT in the SPT process. Therefore, it is urgent to develop a novel SPT platform for overcoming hypoxia in tumors and improving the therapeutic effect of both PTT and PDT. In this work, a novel phototherapeutic platform based on a nanocomposite of aza-BODIPY/manganese dioxide (MnO₂ ) is developed via simple electrostatic self-assembly. In this design, MnO₂ nanosheets, which could produce heat and catalyze endogenous hydrogen peroxide (H₂ O₂ ) to generate oxygen, are prepared as a nanocarrier. After being coated with the as-prepared water-soluble aza-BODIPY-based polymer (PPAIB), the obtained MnO₂ @PPAIB performs as a smart phototherapeutic agent for enhancing the efficiency of both PTT and PDT. More importantly, compared to PPAIB, MnO₂ @PPAIB generates more heat and reactive oxygen species to realize the enhanced therapy effects of PTT and PDT. Hence, this work provides a new method to enhance the therapeutic efficacy of SPT by using a polymer/MnO₂ nanoplatform to improve the oxygen concentration and produce more heat.

Epitaxial growth of gold on silver nanoplates for imaging-guided photothermal therapy

Ag@Au core-shell structure nanoparticles, integrating the good stability of Au and the high surface plasmon resonance property (LSPR) of Ag have been extensively employed for photothermal therapy. Up to now, their sophisticated synthesis still remains a great challenge due to the galvanic replacement effect. Herein, through introduction of Ag, we demonstrated that the Ag@Au core-shell nanoplates were easily synthesized in a galvanic replacement-free fashion with no compromise of heating power. Specifically, through fine-tuning the structure of Ag nanoplates that later served as seeds for the overgrowth of Au, the absorption of resultant nanocrystals can be tailored in ranges from visible to near-infrared. Upon resonant laser irradiation, these Ag@Au nanoplates show the feasibility in photothermally eliminating cancer cells. Furthermore, the high atomic numbers of both Ag and Au elements made the nanoplates promising contrast agents for computed tomography that can be harnessed to guide the tumor ablation. The noticeable regression of the solid tumor, regained body weight, along with the absence of signs indicating inflammation relating the long-term toxicity, all support the promising role of Ag@Au nanoplate as a theranostic agent.

Anchoring Pt Single Atoms on Te Nanowires for Plasmon-Enhanced Dehydrogenation of Formic Acid at Room Temperature

Formic acid (HCOOH), as a promising hydrogen carrier, is renewable, safe, and nontoxic. However, the catalytic dehydrogenation of HCOOH is typically conducted at elevated temperature. Here, HCOOH decomposition is successfully achieved for hydrogen production on the developed Pt single atoms modified Te nanowires with the Pt mass loading of 1.1% (1.1%Pt/Te) at room temperature via a plasmon-enhanced catalytic process. Impressively, 1.1%Pt/Te delivers 100% selectivity for hydrogen and the highest turnover frequency number of 3070 h-1 at 25 °C, which is significantly higher than that of Pt single atoms and Pt nanoclusters coloaded Te nanowires, Pt nanocrystals decorated Te nanowires, and commercial Pt/C. A plasmonic hot-electron driven mechanism rather than photothermal effect domains the enhancement of catalytic activity for 1.1%Pt/Te under light. The transformation of HCOO* to CO2 δ -* on Pt atoms is proved to be the rate-determining step by further mechanistic studies. 1.1%Pt/Te exhibits tremendous catalytic activity toward the decomposition of HCOOH owing to its plasmonic hot-electron driven mechanism, which efficiently stimulates the rate-determining step. In addition, hot electrons generated by the Te atoms nearby Pt single atoms are regarded to directly inject into the reactants adsorbed and activated on Pt single atoms.

Near-Infrared-Triggered Photodynamic, Photothermal, and on Demand Chemotherapy by Multifunctional Upconversion Nanocomposite

In an attempt to integrate photodynamic therapy (PDT) with photothermal therapy and chemotherapy for enhanced anticancer activity, we have rationally synthesized a multifunctional upconversion nanoplatform using NaYF₄:Yb/Tm/Er/Fe nanoparticles (NPs) as the core and NaYbF₄:1% Tm as a shell. The as-synthesized core-shell upconversion (CSU) NPs exhibited diverse and enhanced photoluminescence emissions in a wide range (UV to NIR) consequent upon Fe³⁺ doping in the core and fabrication of an active shell. Subsequently, CSU was first decorated with titania NPs as photosensitizers. Next, the mesoporous silica (MS) shell loaded with doxorubicin (DOX) via a photocleavable Ru complex as the gating molecule was developed around titania-containing CSU. Finally, gold nanorods (GNRs) with localized surface plasmon resonance (LSPR) at 800 nm were incorporated around the MS layer to obtain the multifunctional nanoplatform. We demonstrated that the UV, blue, and NIR emissions from the CSU produced ROS-mediated PDT through titania activation, induced DOX release through photocleavage of the Ru complex, and generated hyperthermia by LSPR activity of GNRs, respectively, upon a single NIR excitation through FRET. The therapeutic efficacy was validated on HeLa cell lines in vitro by various microscopic and biochemical studies under a significantly milder NIR irradiation and lower dosage of the nanoplatforms, which have been further demonstrated as diagnostic nanoprobes for cell imaging.

Upconversion-mediated ZnFe2O4 nanoplatform for NIR-enhanced chemodynamic and photodynamic therapy

ZnFe2O4, a semiconductor catalyst with high photocatalytic activity, is ultrasensitive to ultraviolet (UV) light and tumor H2O2 for producing reactive oxygen species (ROS). Thereby, ZnFe2O4 can be used for photodynamic therapy (PDT) from direct electron transfer and the newly defined chemodynamic therapy (CDT) from the Fenton reaction. However, UV light has confined applicability because of its high phototoxicity, low penetration, and speedy attenuation in the biotissue. Herein, an upconversion-mediated nanoplatform with a mesoporous ZnFe2O4 shell was developed for near-infrared (NIR) light enhanced CDT and PDT. The nanoplatform (denoted as Y-UCSZ) was comprised of upconversion nanoparticles (UCNPs), silica shell, and mesoporous ZnFe2O4 shell and was synthesized through a facile hydrothermal method. The UCNPs can efficiently transfer penetrable NIR photons to UV light, which can activate ZnFe2O4 for producing singlet oxygen thus promoting the Fenton reaction for ROS generation. Besides, Y-UCSZ possesses enormous internal space, which is highly beneficial for housing DOX (doxorubicin, a chemotherapeutic agent) to realize chemotherapy. Moreover, the T 2-weighted magnetic resonance imaging (MRI) effect from Fe3+ and Gd3+ ions in combination with the inherent upconversion luminescence (UCL) imaging and computed tomography (CT) from the UCNPs makes an all-in-one diagnosis and treatment system. Importantly, in vitro and in vivo assays authenticated excellent biocompatibility of the PEGylated Y-UCSZ (PEG/Y-UCSZ) and high anticancer effectiveness of the DOX loaded PEG/Y-UCSZ (PEG/Y-UCSZ&DOX), indicating its potential application in the cancer treatment field.

Multifunctional nanoclusters of NaYF4:Yb3+,Er3+ upconversion nanoparticle and gold nanorod for simultaneous imaging and targeted chemotherapy of bladder cancer

This paper reports successful synthesis of multifunctional nanoclusters of upconversion nanoparticle (UCNP) and gold nanorod (AuNR) through a PEGylation process. UCNPs emit visible luminescence under near-infrared excitation, producing high-contrast images with no background fluorescence. When coupled with AuNRs, the resulting UCNP-AuNR multifunctional nanoclusters are capable of simultaneous detection and treatment of bladder cancer. These UCNP-AuNR nanoclusters are further functionalized with antibodies to epidermal growth factor receptor (EGFR) to target bladder cancer cells known to overexpress EGFRs. This paper demonstrates, for the first time, efficient targeting of bladder cancer cells with UCNP-AuNR nanoclusters. In addition to high-contrast imaging and consequently high sensitivity detection of bladder cancer cells, highly selective optoporation-assisted chemotherapy was accomplished using a dosage of chemotherapy agent significantly lower than any previous reports, within a clinically relevant incubation time window. These results are highly relevant to the eventual human application in which the nanoclusters and chemotherapy drugs will be directly instilled in bladder via urinary catheter.

Water-Dispersible Candle Soot-Derived Carbon Nano-Onion Clusters for Imaging-Guided Photothermal Cancer Therapy

Herein, water-dispersible carbon nano-onion clusters (CNOCs) with an average hydrodynamic size of ≈90 nm are prepared by simply sonicating candle soot in a mixture of oxidizing acid. The obtained CNOCs have high photothermal conversion efficiency (57.5%), excellent aqueous dispersibility (stable in water for more than a year without precipitation), and benign biocompatibility. After polyethylenimine (PEI) and poly(ethylene glycol) (PEG) modification, the resultant CNOCs-PEI-PEG have a high photothermal conversion efficiency (56.5%), and can realize after-wash photothermal cancer cell ablation due to their ultrahigh cellular uptake (21.3 pg/cell), which is highly beneficial for the selective ablation of cancer cells via light-triggered intracellular heat generation. More interestingly, the cellular uptake of CNOCs-PEI-PEG is so high that the internalized nanoagents can be directly observed under a microscope without fluorescent labeling. Besides, in vivo experiments reveal that CNOCs-PEI-PEG can be used for photothermal/photoacoustic dual-modal imaging-guided photothermal therapy after intravenous administration. Furthermore, CNOCs-PEI-PEG can be efficiently cleared from the mouse body within a week, ensuring their excellent long-term biosafety. To the best of the authors' knowledge, the first example of using candle soot as raw material to prepare water-dispersible onion-like carbon nanomaterials for cancer theranostics is represented herein.

Heterogeneous Nanostructures Fabricated via Binding Energy-Controlled Nanowelding

A novel concept for fabricating heterogeneous nanostructures based on different melting temperatures is developed. Au-Ag composite cross-structures are fabricated by nanowelding technologies. During the fabrication of Au-Ag composite cross-structures, Ag nanowires transform into ordered particles decorating the Au nanowire surfaces with an increase in the welding temperature because of the different melting temperatures of Au and Ag. To compare and explain the melting temperatures, the thicknesses of Au and Ag nanowires as parameters are analyzed. Scanning electron microscopy and focused ion beam imaging are used to observe the morphologies and cross sections of the fabricated samples. The evolution of 3D nanostructures is observed by atomic force microscopy, whereas the compositions and binding energies of the nanostructures are determined by X-ray diffraction and X-ray photoelectron spectroscopies. In addition, the atomic structures are analyzed by transmission electron microscopy, and the optical properties of the fabricated nanostructures are evaluated by spectrometry. Furthermore, color filter electrodes are fabricated, and their polarization properties are evaluated by sheet resistance measurements and observing the color and brightness of light-emitting diodes. The proposed method is suitable for application in various fields such as biosensors, optics, and medicine.

Quantitative zeptomolar imaging of miRNA cancer markers with nanoparticle assemblies

Multiplexed detection of small noncoding RNAs responsible for posttranscriptional regulation of gene expression, known as miRNAs, is essential for understanding and controlling cell development. However, the lifetimes of miRNAs are short and their concentrations are low, which inhibits the development of miRNA-based methods, diagnostics, and treatment of many diseases. Here we show that DNA-bridged assemblies of gold nanorods with upconverting nanoparticles can simultaneously quantify two miRNA cancer markers, namely miR-21 and miR-200b. Energy upconversion in nanoparticles affords efficient excitation of fluorescent dyes via energy transfer in the superstructures with core-satellite geometry where gold nanorods are surrounded by upconverting nanoparticles. Spectral separation of the excitation beam and dye emission wavelengths enables drastic reduction of signal-to-noise ratio and the limit of detection to 3.2 zmol/ng_RNA (0.11 amol or 6.5 × 10⁴ copies) and 10.3 zmol/ng_RNA (0.34 amol or 2.1 × 10⁵ copies) for miR-21 and miR-200b, respectively. Zeptomolar sensitivity and analytical linearity with respect to miRNA concentration affords multiplexed detection and imaging of these markers, both in living cells and in vivo assays. These findings create a pathway for the creation of an miRNA toolbox for quantitative epigenetics and digital personalized medicine.

Lesson from Nature: Biomimetic Self-Assembling Phthalocyanines for High-Efficient Photothermal Therapy within the Biological Transparent Window

Development of a facile but high-efficient small organic molecule-based photothermal therapy (PTT) in the in vivo transparent window (800-900 nm) has been regarded as a minimally invasive and most promising strategy for potential clinical cancer treatment. Phthalocyanine (Pc) molecules with remarkable photophysical and photochemical properties as well as high extinction coefficients in the near-infrared region are highly desirable for PTT, but as far satisfying single-component Pc-based PTT within the in vivo transparent window (800-900 nm) has very rarely been reported. Herein, inspired by the self-assembly algorithm of natural bacteriochlorophylls c, d, and e, biomimetic self-assembling tetrahexanoyl Pc Bio-ZnPc with outstanding light-harvesting capacity was demonstrated to exhibit excellent PTT efficacy evidenced by both in vitro and in vivo results, within the biological transparent window.

Designing of UCNPs@Bi@SiO2 Hybrid Theranostic Nanoplatforms for Simultaneous Multimodal Imaging and Photothermal Therapy

Herein, a novel multifunctional nanoplatform was designed toward multimodality imaging and photothermal therapy (PTT). It was found that Bi nanoparticles could grow in situ on the surface of NaYF₄:20%Yb,2%Er@NaYF₄:40%Yb@NaGdF₄ core-shell nanoparticles (labeled as UCNPs). In this structure, UCNPs were mainly employed as an upconversion luminescence (UCL) imaging agent, whereas the Bi nanoparticles worked as an effective CT imaging and photothermal agent. Importantly, a dense SiO₂ shell was employed to protect the Bi nanoparticles from oxidation, and it also endowed the nanoplatform with excellent hydrophilic ability. The effective UCL/CT imaging and PTT performances were emphasized by a series of in vivo experiments, which suggest that the integrated nanoplatform with imaging and therapy functions shows great promise in the biomedical field.