Disposable 3D GNAs/AuNPs DNA‐Circuit Strip for miRNAs Dynamic Quantification

Real‐time quantitative monitoring of miRNAs plays an essential role in diagnosis and therapeutics. Herein, a DSN‐coupled graphene nanoarray/gold nanoparticles (GNAs/AuNPs) carbon paper (CP) electrode for the dynamic, sensitive, and real‐time analysis of miRNAs is reported. GNAs are vertically grown on the conductive CP by radio frequency plasma enhanced chemical vapor deposition, and AuNPs are electrodeposited on CP/GNAs to build a 3D ultrasensitive sensing interface with large specific surface area, good conductivity and biocompatibility. The dynamic quantitative monitoring of microRNA‐21 (miR‐21) is realized by cyclic voltammetry with a series of different concentrations within 16 min, and this 3D GNAs/AuNPs DNA‐circuit strip shows good performance for the simultaneous detection of miR‐21 and miR‐155, and the detection limits are as low as 21.4 and 30.3 am, respectively. Moreover, comparable detection results are achieved for clinical samples between the proposed sensor and qRT‐PCR, suggesting the reliability of the constructed sensor. This ultrasensitive sensing and disposable DNA‐circuit strip with 3D structure can efficiently shorten the diffusion distance between reactive biomolecules and the sensing interface, enhance the hybridization of probes and improve the sensitivity of the biosensor, holding great promise for the rapid, quantitative and dynamic monitoring of multiple low concentrations of biomolecules in point‐of‐care clinical analysis.     

Laser‐Ignited Relay‐Domino‐Like Reactions in Graphene Oxide/CL‐20 Films for High‐Temperature Pulse Preparation of Bi‐Layered Photothermal Membranes

Light‐ignited combustions have been proposed for a variety of industrial and scientific applications. They suffer, however, from ultrahigh light ignition thresholds and poor self‐propagating combustion of typical high‐energy density materials, e.g., 2,4,6,8,10,12‐(hexanitrohexaaza)cyclododecane (CL‐20). Here, reported is that both light ignition and combustion performance of CL‐20 are greatly enhanced by embedding ε‐CL‐20 particles in a graphene oxide (GO) matrix. The GO matrix yields a drastic temperature rise that is sufficient to trigger the combustion of GO/CL‐20 under low laser irradiation (35.6 mJ) with only 6 wt% of GO. The domino‐like reduction‐combustion of the GO matrix can serve as a relay and deliver the decomposition‐combustion of CL‐20 to its neighbor sites, forming a relay‐domino‐like reaction. In particular, a synergistic reaction between GO and CL‐20 occurrs, facilitating more energy release of the GO/CL‐20 composite. The novel relay‐domino‐like reaction coupled with the synergistic reaction of CL‐20 and GO results in a deflagration of the material, which generates a high‐temperature pulse (HTP) that can be guided to produce advanced functional materials. As a proof of concept, a bi‐layered photothermal membrane is prepared by HTP treatment in an extremely simple and fast way, which can serve as a model architecture for efficient interfacial water evaporation.     

Double‐Targeting Explosible Nanofirework for Tumor Ignition to Guide Tumor‐Depth Photothermal Therapy

This study reports a double‐targeting “nanofirework” for tumor‐ignited imaging to guide effective tumor‐depth photothermal therapy (PTT). Typically, ≈30 nm upconversion nanoparticles (UCNP) are enveloped with a hybrid corona composed of ≈4 nm CuS tethered hyaluronic acid (CuS‐HA). The HA corona provides active tumor‐targeted functionality together with excellent stability and improved biocompatibility. The dimension of UCNP@CuS‐HA is specifically set within the optimal size window for passive tumor‐targeting effect, demonstrating significant contributions to both the in vivo prolonged circulation duration and the enhanced size‐dependent tumor accumulation compared with ultrasmall CuS nanoparticles. The tumors featuring hyaluronidase (HAase) overexpression could induce the escape of CuS away from UCNP@CuS‐HA due to HAase‐catalyzed HA degradation, in turn activating the recovery of initially CuS‐quenched luminescence of UCNP and also driving the tumor‐depth infiltration of ultrasmall CuS for effective PTT. This in vivo transition has proven to be highly dependent on tumor occurrence like a tumor‐ignited explosible firework. Together with the double‐targeting functionality, the pathology‐selective tumor ignition permits precise tumor detection and imaging‐guided spatiotemporal control over PTT operation, leading to complete tumor ablation under near infrared (NIR) irradiation. This study offers a new paradigm of utilizing pathological characteristics to design nanotheranostics for precise detection and personalized therapy of tumors.     

Metabolizable Semiconducting Polymer Nanoparticles for Second Near‐Infrared Photoacoustic Imaging

Photoacoustic (PA) imaging in the second near‐infrared (NIR‐II) window (1000–1700 nm) holds great promise for deep‐tissue diagnosis due to the reduced light scattering and minimized tissue absorption; however, exploration of such a noninvasive imaging technique is greatly constrained by the lack of biodegradable NIR‐II absorbing agents. Herein, the first series of metabolizable NIR‐II PA agents are reported based on semiconducting polymer nanoparticles (SPNs). Such completely organic nanoagents consist of π‐conjugated yet oxidizable optical polymer as PA generator and hydrolyzable amphiphilic polymer as particle matrix to provide water solubility. The obtained SPNs are readily degraded by myeloperoxidase and lipase abundant in phagocytes, transforming from nonfluorescent nanoparticles (30 nm) into NIR fluorescent ultrasmall metabolites (≈1 nm). As such, these nanoagents can be effectively cleared out via both hepatobiliary and renal excretions after systematic administration, leaving no toxicity to living mice. Particularly these nanoagents possess high photothermal conversion efficiencies and emit bright PA signals at 1064 nm, enabling sensitive NIR‐II PA imaging of both subcutaneous tumor and deep brain vasculature through intact skull in living animals at a low systematic dosage. This study thus provides a generalized molecular design toward organic metabolizable semiconducting materials for biophotonic applications in NIR‐II window.     

A High‐Sensitivity and Low‐Power Theranostic Nanosystem for Cell SERS Imaging and Selectively Photothermal Therapy Using Anti‐EGFR‐Conjugated Reduced Graphene Oxide/Mesoporous Silica/AuNPs Nanosheets

A high‐sensitivity and low‐power theranostic nanosystem that combines with synergistic photothermal therapy and surface‐enhanced Raman scattering (SERS) mapping is constructed by mesoporous silica self‐assembly on the reduced graphene oxide (rGO) nanosheets with nanogap‐aligned gold nanoparticles (AuNPs) encapsulated and arranged inside the nanochannels of the mesoporous silica layer. Rhodamine 6G (R6G) as a Raman reporter is then encapsulated into the nanochannels and anti‐epidermal growth factor receptor (EGFR) is conjugated on the nanocomposite surface, defined as anti‐EGFR‐PEG‐rGO@CPSS‐Au‐R6G, where PEG is polyethylene glycol and CPSS is carbon porous silica nanosheets. SERS spectra results show that rGO@CPSS‐Au‐R6G enhances 5 × 10⁶ magnification of the Raman signals and thus can be applied in the noninvasive cell tracking. Furthermore, it displays high sensitivity (detection limits: 10^?8m R6G solution) due to the “hot spots” effects by the arrangements of AuNPs in the nanochannels of mesoporous silica. The highly selective targeting of overexpressing EGFR lung cancer cells (A549) is observed in the anti‐EGFR‐PEG‐rGO@CPSS‐Au‐R6G, in contrast to normal cells (MRC‐5). High photothermal therapy efficiency with a low power density (0.5 W cm^?2) of near‐infrared laser can be achieved because of the synergistic effect by conjugated AuNPs and rGO nanosheets. These results demonstrate that the anti‐EGFR‐PEG‐rGO@CPSS‐Au‐R6G is an excellent new theranostic nanosystem with cell targeting, cell tracking, and photothermal therapy capabilities.     

Size‐Dependent Cellular Uptake of DNA Functionalized Gold Nanoparticles

The extensive use of gold nanoparticles (AuNPs) in nanomedicine, especially for intracellular imaging, photothermal therapy, and drug delivery, has necessitated the study of how functionalized AuNPs engage with living biological interfaces like the mammalian cell. Nanoparticle size, shape, surface charge, and surface functionality can affect the accumulation of functionalized AuNPs in cells. Confocal microscopy, flow cytometry, and inductively coupled plasma mass spectrometry demonstrate that CaSki cells, a human cervical cancer cell line, internalize AuNPs functionalized with hairpin, single stranded, and double stranded DNA differently. Surface charge and DNA conformation are shown to have no effect on the cell‐nanoparticle interaction. CaSki cells accumulate small DNA‐AuNPs in greater quantities than large DNA‐AuNPs, demonstrating that size is the major contributor to cellular uptake properties. These data suggest that DNA‐AuNPs can be easily tailored through modulation of size to design functional AuNPs with optimal cellular uptake properties and enhanced performance in nanomedicine applications.     

Flexible Photothermal Assemblies with Tunable Gold Patterns for Improved Imaging‐Guided Synergistic Therapy

Self‐assembly of gold nanoparticles demonstrates a promising approach to realize enhanced photoacoustic imaging (PAI) and photothermal therapy (PTT) for accurate diagnosis and efficient cancer therapy. Herein, unique photothermal assemblies with tunable patterns of gold nanoparticles (including arcs, rings, ribbons, and vesicles) on poly(lactic‐co‐glycolic acid) (PLGA) spheres are constructed taking advantage of emulsion‐confined and polymer‐directed self‐assembly strategies. The influencing factors and formation mechanism to produce the assemblies are investigated in details. Both the emulsion structure and migration behaviors of amphiphilic block copolymer tethered gold nanoparticles are found to contribute to the formation of versatile photothermal assemblies. Hyaluronic acid‐modified R‐PLGA‐Au (RPA) exhibits outstanding photothermal performances under NIR laser irradiation, which is induced by strong plasmonic coupling between adjacent gold nanoparticles. It is interesting that secondary assembly of RPA can be triggered by NIR laser irradiation. Prolonged residence time in tumors is achieved after RPA assemblies are fused into superstructures with larger sizes, realizing real‐time monitoring of the therapeutic processes via PAI with enhanced photoacoustic signals. Notably, synergistic effect resulting from PTT‐enhanced chemotherapy is realized to demonstrate high antitumor performance. This work provides a facile strategy to construct flexible photothermal assemblies with favorable properties for imaging‐guided synergistic therapy.     

Programmed Nanoparticle‐Loaded Nanoparticles for Deep‐Penetrating 3D Cancer Therapy

Tumors are 3D, composed of cellular agglomerations and blood vessels. Therapies involving nanoparticles utilize specific accumulations due to the leaky vascular structures. However, systemically injected nanoparticles are mostly uptaken by cells located on the surfaces of cancer tissues, lacking deep penetration into the core cancer regions. Herein, an unprecedented strategy, described as injecting “nanoparticle‐loaded nanoparticles” to address the long‐lasting problem is reported for effective surface‐to‐core drug delivery in entire 3D tumors. The “nanoparticle‐loaded nanoparticle” is a silica nanoparticle (≈150 nm) with well‐developed, interconnected channels (diameter of ≈30 nm), in which small gold nanoparticles (AuNPs) (≈15 nm) with programmable DNA are located. The nanoparticle (AuNPs)‐loaded nanoparticles (silica): (1) can accumulate in tumors through leaky vascular structures by protecting the inner therapeutic AuNPs during blood circulation, and then (2) allow diffusion of the AuNPs for penetration into the entire surface‐to‐core tumor tissues, and finally (3) release a drug triggered by cancer‐characteristic pH gradients. The hierarchical “nanoparticle‐loaded nanoparticle” can be a rational design for cancer therapies because the outer large nanoparticles are effective in blood circulation and in protection of the therapeutic nanoparticles inside, allowing the loaded small nanoparticles to penetrate deeply into 3D tumors with anticancer drugs.     

Cytotoxicity of Ultrasmall Gold Nanoparticles on Planktonic and Biofilm Encapsulated Gram‐Positive Staphylococci

The emergence of multidrug resistant bacteria, especially biofilm‐associated Staphylococci, urgently requires novel antimicrobial agents. The antibacterial activity of ultrasmall gold nanoparticles (AuNPs) is tested against two gram positive: S. aureus and S. epidermidis and two gram negative: Escherichia coli and Pseudomonas aeruginosa strains. Ultrasmall AuNPs with core diameters of 0.8 and 1.4 nm and a triphenylphosphine‐monosulfonate shell (Au0.8MS and Au1.4MS) both have minimum inhibitory concentration (MIC) and minimum bactericidal concentration of 25 × 10^?6m [Au]. Disc agar diffusion test demonstrates greater bactericidal activity of the Au0.8MS nanoparticles over Au1.4MS. In contrast, thiol‐stabilized AuNPs with a diameter of 1.9 nm (AuroVist) cause no significant toxicity in any of the bacterial strains. Ultrasmall AuNPs cause a near 5 log bacterial growth reduction in the first 5 h of exposure, and incomplete recovery after 21 h. Bacteria show marked membrane blebbing and lysis in biofilm‐associated bacteria treated with ultrasmall AuNP. Importantly, a twofold MIC dosage of Au0.8MS and Au1.4MS each cause around 80%–90% reduction in the viability of Staphylococci enveloped in biofilms. Altogether, this study demonstrates potential therapeutic activity of ultrasmall AuNPs as an effective treatment option against staphylococcal infections.     

Humidity‐Responsive Single‐Nanoparticle‐Layer Plasmonic Films

2D materials possess many interesting properties, and have shown great application potentials. In this work, the development of humidity‐responsive, 2D plasmonic nanostructures with switchable chromogenic properties upon wetting–dewetting transitions is reported. By exploiting DNA hybridization‐directed anchoring of gold nanoparticles (AuNPs) on substrates, a series of single‐nanoparticle‐layer (SNL) plasmonic films is fabricated. Due to the collective plasmonic responses in SNL, these ultrathin 2D films display rapid and reversible red‐blue color change upon the wetting–dewetting transition, suggesting that hydration‐induced microscopic plasmonic coupling between AuNPs is replicated in the macroscopic, centimeter‐scale films. It is also found that hydration finely tunes the electric field distribution between AuNPs in the SNL film, based on which responsive surface‐enhanced Raman scattering substrates with spatially homogeneous hot spots are developed. Thus it is expected that DNA‐mediated 2D SNL structures open new avenues for designing miniaturized plasmonic nanodevices with various applications.     

Ultrasmall Cu2‐xS Nanodots for Highly Efficient Photoacoustic Imaging‐Guided Photothermal Therapy

Monodisperse, ultrasmall (<5 nm) Cu_2?xS nanodots (u‐Cu_2?xS NDs) with significantly strong near‐infrared absorption and conversion are successfully demonstrated for effective deep‐tissue photoacoustic imaging‐guided photothermal therapy both in vitro and in vivo. Owing to ultrasmall nanoparticle size and high water dispersibility as well as long stability, such nanodots possess a prolonged circulation in blood and good passive accumulation within tumors through the enhanced permeability and retention effect. These u‐Cu_2?xS NDs have negligible side effects to both blood and normal tissues according to in vivo toxicity evaluations for up to 3 months, showing excellent hemo/histocompatibility. Furthermore, these u‐Cu_2?xS NDs can be thoroughly cleared through feces and urine within 5 days, showing high biosafety for further potential clinical translation. This novel photoacoustic imaging‐guided photothermal therapy based on u‐Cu_2?xS NDs composed of a single component shows great prospects as a multifunctional nanoplatform with integration and multifunction for cancer diagnosis and therapy.     

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

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

Sub‐5 nm Metal Nanogaps: Physical Properties,Fabrication Methods,and Device Applications

Sub‐5 nm metal nanogaps have attracted widespread attention in physics, chemistry, material sciences, and biology due to their physical properties, including great plasmon‐enhanced effects in light–matter interactions and charge tunneling, Coulomb blockade, and the Kondo effect under an electrical stimulus. These properties especially meet the needs of many cutting‐edge devices, such as sensing, optical, molecular, and electronic devices. However, fabricating sub‐5 nm nanogaps is still challenging at the present, and scaled and reliable fabrication, improved addressability, and multifunction integration are desired for further applications in commercial devices. The aim of this work is to provide a comprehensive overview of sub‐5 nm nanogaps and to present recent advancements in metal nanogaps, including their physical properties, fabrication methods, and device applications, with the ultimate aim to further inspire scientists and engineers in their research.     

Light‐Responsive Biodegradable Nanorattles for Cancer Theranostics

Cancer nanotheranostics, integrating both diagnostic and therapeutic functions into nanoscale agents, are advanced solutions for cancer management. Herein, a light‐responsive biodegradable nanorattle‐based perfluoropentane‐(PFP)‐filled mesoporous‐silica‐film‐coated gold nanorod (GNR@SiO₂‐PFP) is strategically designed and prepared for enhanced ultrasound (US)/photoacoustic (PA) dual‐modality imaging guided photothermal therapy of melanoma. The as‐prepared nanorattles are composed of a thin mesoporous silica film as the shell, which endows the nanoplatform with flexible morphology and excellent biodegradability, as well as large cavity for PFP filling. Upon 808 nm laser irradiation, the loaded PFP will undergo a liquid–gas phase transition due to the heat generation from GNRs, thus generating nanobubbles followed by the coalescence into microbubbles. The conversion of nanobubbles to microbubbles can improve the intratumoral permeation and retention in nonmicrovascular tissue, as well as enhance the tumor‐targeted US imaging signals. This nanotheranostic platform exhibits excellent biocompatibility and biodegradability, distinct gas bubbling phenomenon, good US/PA imaging contrast, and remarkable photothermal efficiency. The results demonstrate that the GNR@SiO₂‐PFP nanorattles hold great potential for cancer nanotheranostics.     

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

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

Programmable NIR‐II Photothermal‐Enhanced Starvation‐Primed Chemodynamic Therapy using Glucose Oxidase‐Functionalized Ancient Pigment Nanosheets

Chemodynamic therapy (CDT) has attracted considerable attention recently, but the poor reaction kinetics restrict its practical utility in clinic. Herein, glucose oxidase (GOx) functionalized ancient pigment nanosheets (SrCuSi₄O₁₀, SC) for programmable near‐infrared II (NIR‐II) photothermal‐enhanced starvation primed CDT is developed. The SC nanosheets (SC NSs) are readily exfoliated from SC bulk suspension in water and subsequently functionalized with GOx to form the nanocatalyst (denoted as SC@G NSs). Upon laser irradiation, the photothermal effect of SC NSs can enhance the catalytic activity of GOx for NIR‐II photothermal‐enhanced starvation therapy, which effectively eliminates intratumoral glucose and produces abundant hydrogen peroxide (H₂O₂). Importantly, the high photothermal‐conversion efficiency (46.3%) of SC@G NSs in second biological window permits photothermal therapy of deep‐seated tumors under the guidance of NIR‐II photoacoustic imaging. Moreover, the acidity amplification due to gluconic acid generation will in turn accelerate the degradation of SC NSs, facilitating the release of strontium (Sr) and copper (Cu) ions. Both the elevated H₂O₂ and the released ions will prime the Cu²⁺/Sr²⁺‐H₂O₂ reaction for enhanced CDT. Thus, a programmable NIR‐II photothermal‐enhanced starvation primed CDT is established to combat cancer with minimal side effects.     

Split‐GFP: SERS Enhancers in Plasmonic Nanocluster Probes

The assembly of plasmonic metal nanoparticles into hot spot surface‐enhanced Raman scattering (SERS) nanocluster probes is a powerful, yet challenging approach for ultrasensitive biosensing. Scaffolding strategies based on self‐complementary peptides and proteins are of increasing interest for these assemblies, but the electronic and the photonic properties of such hybrid nanoclusters remain difficult to predict and optimize. Here, split‐green fluorescence protein (sGFP) fragments are used as molecular glue and the GFP chromophore is used as a Raman reporter to assemble a variety of gold nanoparticle (AuNP) clusters and explore their plasmonic properties by numerical modeling. It is shown that GFP seeding of plasmonic nanogaps in AuNP/GFP hybrid nanoclusters increases near‐field dipolar couplings between AuNPs and provides SERS enhancement factors above 10⁸. Among the different nanoclusters studied, AuNP/GFP chains allow near‐infrared SERS detection of the GFP chromophore imidazolinone/exocyclic C?C vibrational mode with theoretical enhancement factors of 10⁸–10⁹. For larger AuNP/GFP assemblies, the presence of non‐GFP seeded nanogaps between tightly packed nanoparticles reduces near‐field enhancements at Raman active hot spots, indicating that excessive clustering can decrease SERS amplifications. This study provides rationales to optimize the controlled assembly of hot spot SERS nanoprobes for remote biosensing using Raman reporters that act as molecular glue between plasmonic nanoparticles.     

Dual‐Peak Absorbing Semiconducting Copolymer Nanoparticles for First and Second Near‐Infrared Window Photothermal Therapy: A Comparative Study

Near‐infrared (NIR) light is widely used for noninvasive optical diagnosis and phototherapy. However, current research focuses on the first NIR window (NIR‐I, 650–950 nm), while the second NIR window (NIR‐II, 1000–1700 nm) is far less exploited. The development of the first organic photothermal nanoagent (SPN_I‐II) with dual‐peak absorption in both NIR windows and its utilization in photothermal therapy (PTT) are reported herein. Such a nanoagent comprises a semiconducting copolymer with two distinct segments that respectively and identically absorb NIR light at 808 and 1064 nm. With the photothermal conversion efficiency of 43.4% at 1064 nm generally higher than other inorganic nanomaterials, SPN_I‐II enables superior deep‐tissue heating at 1064 nm over that at 808 nm at their respective safety limits. Model deep‐tissue cancer PTT at a tissue depth of 5 mm validates the enhanced antitumor effect of SPN_I‐II when shifting laser irradiation from the NIR‐I to the NIR‐II window. The good biodistribution and facile synthesis of SPN_I‐II also allow it to be doped with an NIR dye for fluorescence‐imaging‐guided NIR‐II PTT through systemic administration. Thus, this study paves the way for the development of new polymeric nanomaterials to advance phototherapy.     

MOF‐Confined Sub‐2 nm Atomically Ordered Intermetallic PdZn Nanoparticles as High‐Performance Catalysts for Selective Hydrogenation of Acetylene

Controllable synthesis of ultrasmall atomically ordered intermetallic nanoparticles is a challenging task, owing to the high temperature commonly required for the formation of intermetallic phases. Here, a metal–organic framework (MOF)‐confined co‐reduction strategy is developed for the preparation of sub‐2 nm intermetallic PdZn nanoparticles, by employing the well‐defined porous structures of calcinated ZIF‐8 (ZIF‐8C) and an in situ co‐reduction therein. HAADF‐STEM, HRTEM, and EDS characterizations reveal the homogeneous dispersion of these sub‐2 nm intermetallic PdZn nanoparticles within the ZIF‐8C frameworks. XRD, XPS, and EXAFS measurements further confirm the atomically ordered intermetallic phase nature of these sub‐2 nm PdZn nanoparticles. Selective hydrogenation of acetylene evaluation results show the excellent catalytic properties of the sub‐2 nm intermetallic PdZn, which result from the energetically more favorable path for acetylene hydrogenation and ethylene desorption over the ultrasmall particles than over larger‐sized intermetallic PdZn as revealed by density functional theory (DFT) calculations. Moreover, this protocol is also extendable for the preparation of sub‐2 nm intermetallic PtZn nanoparticles and is expected to provide a novel methodology in synthesizing ultrasmall atomically ordered intermetallic nanomaterials by rationally functionalizing MOFs.     

J‐Aggregates of Organic Dye Molecules Complexed with Iron Oxide Nanoparticles for Imaging‐Guided Photothermal Therapy Under 915‐nm Light

Recently, the development of nano‐theranostic agents aiming at imaging guided therapy has received great attention. In this work, a near‐infrared (NIR) heptamethine indocyanine dye, IR825, in the presence of cationic polymer, polyallylamine hydrochloride (PAH), forms J‐aggregates with red‐shifted and significantly enhanced absorbance. After further complexing with ultra‐small iron oxide nanoparticles (IONPs) and the followed functionalization with polyethylene glycol (PEG), the obtained IR825@PAH‐IONP‐PEG composite nanoparticles are highly stable in different physiological media. With a sharp absorbance peak, IR825@PAH‐IONP‐PEG can serve as an effective photothermal agent under laser irradiation at 915 nm, which appears to be optimal in photothermal therapy application considering its improved tissue penetration compared with 808‐nm light and much lower water heating in comparison to 980‐nm light. As revealed by magnetic resonance (MR) imaging, those nanoparticles after intravenous injection exhibit high tumor accumulation, which is then harnessed for in vivo photothermal ablation of tumors, achieving excellent therapeutic efficacy in a mouse tumor model. This study demonstrates for the first time that J‐aggregates of organic dye molecules are an interesting class of photothermal material, which when combined with other imageable nanoprobes could serve as a theranostic agent for imaging‐guided photothermal therapy of cancer.