Long Circulation Red‐Blood‐Cell‐Mimetic Nanoparticles with Peptide‐Enhanced Tumor Penetration for Simultaneously Inhibiting Growth and Lung Metastasis of Breast Cancer

Limited blood circulation and poor tumor penetration are two main obstacles hampering the clinical translation of conventional nanosized drug delivery systems (NDDS). Here, red‐blood‐cell (RBC)‐mimetic nanoparticles (NPs) with long circulation and peptide‐enhanced tumor penetration for treating metastatic breast cancer are reported. The RBC‐mimetic NPs are composed of a paclitaxel (PTX)‐loaded polymeric core and a hydrophilic RBC vesicle shell. The RBC‐mimetic NPs display dramatically elongated blood circulation with an elimination half time of 32.8 h, 5.8‐fold higher than that of the parental polymeric NPs (i.e., 5.6 h). Moreover, the experimental results demonstrate that the tumor penetration ability of the RBC‐mimetic NPs can be significantly improved by coadministrating with a tumor‐penetrating peptide iRGD. Antitumor studies using a metastatic 4T1 breast tumor model show that RBC‐mimetic NPs in combination with iRGD significantly inhibit over 90% of the tumor growth and suppress 95% of the lung metastasis, much more efficient than PTX‐loaded polymer NP alone or the combination of polymer NPs and iRGD. The results reveal the importance of both long circulation and tumor penetration of nanosized drugs for efficient cancer therapy, which can provide a new insight for NDDS design.     

Tumor‐Microenvironment‐Adaptive Nanoparticles Codeliver Paclitaxel and siRNA to Inhibit Growth and Lung Metastasis of Breast Cancer

Prolonged circulation, specific and effective uptake by tumor cells, and rapid intracellular drug release are three main factors for the drug delivery systems to win the battle against metastatic breast cancer. In this work, a tumor microenvironment‐adaptive nanoparticle co‐loading paclitaxel (PTX) and the anti‐metastasis siRNA targeting Twist is prepared. The nanoparticle consists of a pH‐sensitive core, a cationic shell, and a matrix metalloproteinase (MMP)‐cleavable polyethylene glycol (PEG) corona conjugated via a peptide linker. PEG will be cut away by MMPs at the tumor site, which endows the nanoparticle with smaller particle size and higher positive charge, leading to more efficient cellular uptake in tumor cells and higher intra‐tumor accumulation of both PTX and siRNA in the 4T1 tumor‐bearing mice models compared to the nanoparticles with irremovable PEG. In addition, acid‐triggered drug release in endo/lysosomes is achieved through the pH‐sensitive core. As a result, the MMP/pH dual‐sensitive nanoparticles significantly inhibit tumor growth and pulmonary metastasis. Therefore, this tumor‐microenvironment‐adaptive nanoparticle can be a promising codelivery vector for effective therapy of metastatic breast cancer due to simultaneously satisfying the requirements of long circulating time, efficient tumor cell targeting, and fast intracellular drug release.     

Modulation of Intracellular Oxygen Pressure by Dual‐Drug Nanoparticles to Enhance Photodynamic Therapy

Oxygen plays an essential role in the photodynamic therapy (PDT) of cancer. However, hypoxia inside tumors severely attenuates the therapeutic effect of PDT. To address this issue, a novel strategy is reported for cutting off the oxygen consumption pathway by using sub‐50 nm dual‐drug nanoparticles (NPs) to attenuate the hypoxia‐induced resistance to PDT and to enhance PDT efficiency. Specifically, dual‐drug NPs that encapsulate photosensitizer (PS) verteporfin (VER) and oxygen‐regulator atovaquone (ATO) with sub‐50 nm diameters can penetrate deep into the interior regions of tumors and effectively deliver dual‐drug into tumor tissues. Then, ATO released from NPs efficiently reduce in advance cellular oxygen consumption by inhibition of mitochondria respiratory chain and further heighten VER to generate greater amounts of ¹O₂ in hypoxic tumor. As a result, accompanied with the upregulated oxygen content in tumor cells and laser irradiation, the dual‐drug NPs exhibit powerful and overall antitumor PDT effects both in vitro and in vivo, and even tumor elimination. This study presents a potential appealing clinical strategy in photodynamic eradication of tumors.     

Ultrasmall Confined Iron Oxide Nanoparticle MSNs as a pH‐Responsive Theranostic Platform

A unique mesoporous silica nanoparticles (MSNs)‐based theranostic platform with ultrasmall iron oxide nanoparticles (NPs) confined within mesopore network has been developed by a facile but efficient physical‐vapor‐infiltration (PVI) method. The highly dispersed Fe species within mesopore channels can synchronously function as the non‐toxic contrast agents for highly efficient T₁‐weighted MR imaging, and as anchoring sites for anti‐cancer drug molecule loading and pH‐responsive release based on the special metal‐ligand coordination bonding between the Fe species and drug molecules. Moreover, the obtained Fe‐MSNs exhibit favorable biocompatibility, enhanced chemotherapeutic efficacy and concurrently diminished side effects due to the non‐specific attack of chemotherapeutic drugs, as well as the capability in circumventing the multidrug resistance (MDR) of cancer cells and suppressing the metastasis of tumor cells in vitro and in vivo. This pH‐resoponsive theranostic agent provides a new promising MSNs‐based anti‐cancer nanomedicine for future biomedical application.     

Smart Tumor Microenvironment‐Responsive Nanotheranostic Agent for Effective Cancer Therapy

The tumor microenvironment (TME), which includes acidic and hypoxic conditions, severely impedes the therapeutic efficacy of antitumor agents. Herein, MnO₂‐loaded, bovine serum albumin, and PEG co‐modified mesoporous CaSiO₃ nanoparticles (CaM‐PB NPs) are developed as a nanoplatform with sequential theranostic functions for the engineering of TME. The MnO₂ NPs generate O₂ in situ by reacting with endogenous H₂O₂, relieving the hypoxic state of the TME that further modulates the cancer cell cycle status to S phase, which improves the potency of co‐loaded S phase‐sensitive chemotherapeutic drugs. After the hypoxia relief, CaM‐PB can sustainably release drugs due to the enlarged pores of mesoporous CaSiO₃ in the acidic TME, preventing the drug pre‐leakage into the blood circulation and insufficient drug accumulation at tumor sites. Moreover, the Mn²⁺ released from the MnO₂ NPs at tumor sites can potentially serve as a diagnostic agent, enabling the identification of tumor regions by T₁‐weighted magnetic resonance imaging during therapy. In vivo pharmacodynamics results demonstrate that these synergetic effects caused by CaM‐PB NPs significantly contribute to the inhibition of tumor progression. Therefore, the CaM‐PB NPs with sequential theranostic functions are a promising system for effective cancer therapy.     

PEGylated Polypyrrole Nanoparticles Conjugating Gadolinium Chelates for Dual‐Modal MRI/Photoacoustic Imaging Guided Photothermal Therapy of Cancer

Polypyrrole nanoparticles conjugating gadolinium chelates were successfully fabricated for dual‐modal magnetic resonance imaging (MRI) and photoacoustic imaging guided photothermal therapy of cancer, from a mixture of pyrrole and pyrrole‐1‐propanoic acid through a facile one‐step aqueous dispersion polymerization, followed by covalent attachment of gadolinium chelate, using polyethylene glycol as a linker. The obtained PEGylated poly­pyrrole nanoparticles conjugating gadolinium chelates (Gd‐PEG‐PPy NPs), sized around around 70 nm, exhibited a high T₁ relaxivity coefficient of 10.61 L mm ^?1 s^?1, more than twice as high as that of the relating free Gd³⁺ complex (4.2 L mm ^–1 s^?1). After 24 h intravenous injection of Gd‐PEG‐PPy NPs, the tumor sites exhibited obvious enhancement in both T₁‐weighted MRI intensity and photoacoustic signal compared with that before injection, indicating the efficient accumulation of Gd‐PEG‐PPy NPs due to the introduction of the PEG layer onto the particle surface. In addition, tumor growth could be effectively inhibited after treatment with Gd‐PEG‐PPy NPs in combination with near‐infrared laser irradiation. The passive targeting and high MRI/photo­acoustic contrast capability of Gd‐PEG‐PPy NPs are quite favorable for precise cancer diagnosing and locating the tumor site to guide the external laser irradiation for photothermal ablation of tumors without damaging the surrounding healthy tissues. Therefore, Gd‐PEG‐PPy NPs may assist in better monitoring the therapeutic process, and contribute to developing more effective “personalized medicine,” showing great potential for cancer diagnosis and therapy.     

Targeting Efficiency and Biodistribution of Zoledronate Conjugated Docetaxel Loaded Pegylated PBCA Nanoparticles for Bone Metastasis

In an attempt to improve tumor localization of docetaxel (DTX)‐loaded nanoparticles (NPs), zoledronic acid (ZOL) is used as a ligand to target bone metastasis. DTX‐loaded ZOL‐conjugated polyethylene glycol (PEG)ylated polybutyl cyanoacrylate (PBCA) NPs are prepared using an anionic polymerization technique. PBCA‐PEG‐ZOL NPs are subjected to cytotoxic assay in both BO2 and MCF‐7 cell lines. Cell cycle arrest and apoptosis induced by the PBCA‐PEG‐ZOL NPs are studied. Quantitative cellular uptake, NP uptake route characterization, confocal microscopy and IPP/ApppI levels are performed. PBCA‐PEG‐ZOL NPs show an enhanced cytotoxic effect in both BO2 as well as MCF‐7 cell lines due to higher uptake following ZOL‐mediated endocytosis. The molecular basis of apoptosis reveals the involvement of a cytoplasmic protein in activating the programmed cell death pathway. Route characterization studies reveal that PBCA‐PEG‐ZOL NPs uptake is not completely blocked even by using both inhibitors (genistein and phenyl arsinoxide) simultaneously, conferring that uptake is not entirely based upon clathrin or caveolae. PBCA‐PEG‐ZOL NPs showed 7 and 5.3 times increase in IPP and ApppI production, in comparison to ZOL treatment, and 138 times higher than the control group in MCF‐7 cell line. In BO2 cell line, after treatment with NPs, IPP was 5.35 times higher than ZOL solution. No ApppI in BO2 cell line after treatment with NPs and ZOL solution was found. NP distribution in tumor infected bone is also significantly high in comparison to the normal bone at any time point. It is concluded that ZOL‐conjugated NPs provide an efficient and targeted delivery of DTX, with synergistic effects. Thus, these NPs present a promising treatment in the near future, by actively targeting metastatic tumor.     

Gold Core‐DNA‐Silver Shell Nanoparticles with Intense Plasmonic Chiroptical Activities

The strong plasmonic chiroptical activities of gold core‐DNA‐silver shell nanoparticles (NPs) are reported for the first time, using cytosine‐rich single‐stranded DNA as the template for the guidance of silver shell growth. The anisotropy factor of the optically active NPs at 420 nm reaches 1.93 × 10^?2. Their chiroptical properties are likely induced by the DNA–plasmon interaction and markedly amplified by the strong electromagnetic coupling between the gold core and silver shell.     

Hyperbranched Polyglycerol‐Grafted Superparamagnetic Iron Oxide Nanoparticles: Synthesis,Characterization, Functionalization,Size Separation,Magnetic Properties,and Biological Applications

For biomedical application of nanoparticles, the surface chemical functionality is very important to impart additional functions, such as solubility and stability in a physiological environment, and targeting specificity as an imaging probe and a drug carrier. Although polyethylene glycol (PEG) has been used extensively, here, it is proposed that hyperbranched polyglycerol (PG) is a good or even better alternative to PEG. Superparamagnetic iron oxide nanoparticles (SPIONs) prepared using a polyol method are directly functionalized with PG through ring‐opening polymerization of glycidol. The resulting SPION‐PG is highly soluble in pure water (>40 mg mL^?1) and in a phosphate buffer solution (>25 mg mL^?1). Such high solubility enables separation of SPION‐PG according to size using size exclusion chromatography (SEC). The size‐separated SPION‐PG shows a gradual increase in transverse relaxivity (r₂) with increasing particle size. For biological application, SPION‐PG is functionalized through multistep organic transformations (–OH → –OTs (tosylate) → –N₃ → –RGD) including click chemistry as a key step to impart targeting specificity by immobilization of cyclic RGD peptide (Arg‐Gly‐Asp‐D ‐Tyr‐Lys) on the surface. The targeting effect is demonstrated by the cell experiments; SPION‐PG‐RGD is taken up by the cells overexpressing α_vβ₃‐integrin such as U87MG and A549.     

Core–Shell Nanoparticle Interface and Wetting Properties

Latex colloids are among the most promising materials for broad thin film applications due to their facile surface functionalization. Yet, the effect of these colloids on chemical film and wetting properties cannot be easily evaluated. At the nanoscale, core–shell particles can deform and coalesce during thermal annealing, yielding fine‐tuned physical properties. Two different core–shell systems (soft and rigid) with identical shells but with chemically different core polymers and core sizes are investigated. The core–shell nanoparticles (NPs) are probed during thermal annealing in order to investigate their behavior as a function of nanostructure size and rigidity. X‐ray scattering allows to follow the re‐arrangement of the NPs and the structural evolution in situ during annealing. Evaluation by real‐space imaging techniques reveals a disappearance of the structural integrity and a loss of NP boundaries. The possibility to fine‐tune the wettability by tuning the core–shell NPs morphology in thin films provides a facile template methodology for repellent surfaces.     

Camouflaging Nanoparticles with Brain Metastatic Tumor Cell Membranes: A New Strategy to Traverse Blood–Brain Barrier for Imaging and Therapy of Brain Tumors

Glioblastoma multiforme is one of the most fatal intracranial tumors with no effective treatment. The drug concentration in tumor sites is usually insufficient to reach therapeutic levels, due to poor blood–brain‐barrier (BBB) permeability and short biological half‐life. Inspired by the proneness of those malignant tumors to brain metastasis, a brain metastatic tumor cell membrane‐coated nanocarrier with core–shell structure is constructed to cross BBB for imaging and photothermal therapy of early brain tumors. The cell membranes as the shell are extracted from different metastatic tumor cells, which endow the nanoparticles with BBB‐crossing ability and long circulation. Indocyanine green (ICG)‐loaded polymeric nanoparticle as the core allows fluorescence imaging and phototherapy of brain tumors. The as‐prepared biomimetic nanoparticles display superb BBB penetration and effective suppression of tumor growth. These findings suggest the biomimetic nanotechnology provides a new insight for the design of BBB‐crossing nanomaterials and is promising to treat brain diseases.     

A Multi‐Gradient Targeting Drug Delivery System Based on RGD‐l‐TRAIL‐Labeled Magnetic Microbubbles for Cancer Theranostics

The accurately and efficiently targeted delivery of therapeutic/diagnostic agents into tumor areas in a controllable fashion remains a big challenge. Here, a novel cancer targeting magnetic microbubble is elaborately fabricated. First, the γ‐Fe₂O₃ magnetic iron oxide nanoparticles are optimized to chemically conjugate on the surface of polymer microbubbles. Then, arginine‐glycine‐aspartic acid‐l ‐tumor necrosis factor‐related apoptosis‐inducing ligand (RGD‐l ‐TRAIL), antitumor targeting fusion protein, is precisely conjugated with magnetic nanoparticles of microbubbles to construct RGD molecularly targeted magnetic microbubble, which is defined as RGD‐l ‐TRAIL@MMBs. Such RGD‐l ‐TRAIL@MMBs is endowed with the multigradient cascade targeting ability following by magnetic targeting, RGD, as well as enhanced permeability and retention effect regulated targeting to result in high cancerous tissue targeting efficiency. Due to the highly specific accumulation of RGD‐l ‐TRAIL@MMBs in the tumor, the accurate diagnostic information of tumor can be obtained by dual ultrasound and magnetic resonance imaging. After imaging, the TRAIL molecules as anticancer agent also get right into the cancer cells by nanoparticle‐ and RGD‐mediated endocytosis to effectively induce the tumor cell apoptosis. Therefore, RGD‐l ‐TRAIL conjugated magnetic microbubbles could be developed as a molecularly targeted multimodality imaging delivery system with the addition of chemotherapeutic cargoes to improve cancer diagnosis and therapy.     

Core–Shell Nanoparticles: Characterizing Multifunctional Materials beyond Imaging—Distinguishing and Quantifying Perfect and Broken Shells

Core–shell nanoparticles (NPs) are amongst the most promising candidates in the development of new functional materials. Their fabrication and characterization are challenging, in particular when thin and intact shells are needed. To date no technique has been available that differentiates between intact and broken or cracked shells. Here a method is presented to distinguish and quantify these types of shells in a single cyclic voltammetry experiment by using the different electrochemical reactivities of the core and the shell material. A simple comparison of the charge measured during the stripping of the core material before and after the removal of the shell makes it possible to determine the quality of the shells and to estimate their thickness. As a proof‐of‐concept two multifunctional examples of core–shell NPs, Fe₃O₄@Au and Au@SnO₂, are used. This general and original method can be applied whenever core and shell materials show different redox properties. Because billions of NPs are probed simultaneously and at a low cost, this method is a convenient new screening tool for the development of new multifunctional core–shell materials and is hence a powerful complementary technique or even an alternative to the state‐of‐the‐art characterization of core–shell NPs by TEM.     

Facile Fabrication of Highly Dispersed Pd@Ag Core–Shell Nanoparticles Embedded in Spirulina platensis by Electroless Deposition and Their Catalytic Properties

Microorganisms are widely used as the biotemplates for producing micro/nanomaterials owing to their unique features, such as exquisite morphology, renewable, and environmentally friendly. However, mass intracellular synthesis of uniformly dispersed nanoparticles (NPs) inside microorganisms is still challenging, especially in a predictable and controllable manner. Here, a facile and efficiency strategy is proposed to controllably produce highly dispersed and surfactant‐free Pd@Ag core–shell NPs within the Spirulina platensis (Sp.) cells. In this approach, the Sp. cells' permeability is enhanced by the hydrochloric acid treatment first, which enables the Pd NPs penetrate the cell envelope and distribute uniformly inside the cells, and then they can work as the catalytic seeds for the following electroless silver deposition, resulting in the intracellular fabrication of Pd@Ag core–shell NPs with no agglomeration. The Pd@Ag NPs show excellent catalytic activity (turnover frequency is up to 2893 h^?1 for the 6.32 nm Pd@Ag NPs), good stability, and recyclability toward the 4‐nitrophenol reductions. The excellent properties are attributed to the asymmetrical core–shell structure, small size, and good dispersion of Pd@Ag NPs. Due to its facility, cost‐effectiveness, and versatility, this method can be expanded to other microorganisms, so it opens tremendous opportunities for various metallic nanoparticles intracellular synthesis as well as the practical application.     

Biocompatible D–A Semiconducting Polymer Nanoparticle with Light‐Harvesting Unit for Highly Effective Photoacoustic Imaging Guided Photothermal Therapy

The development of nanotheranostic agents that integrate diagnosis and therapy for effective personalized precision medicine has obtained tremendous attention in the past few decades. In this report, biocompatible electron donor–acceptor conjugated semiconducting polymer nanoparticles (PPor‐PEG NPs) with light‐harvesting unit is prepared and developed for highly effective photoacoustic imaging guided photothermal therapy. To the best of our knowledge, it is the first time that the concept of light‐harvesting unit is exploited for enhancing the photoacoustic signal and photothermal energy conversion in polymer‐based theranostic agent. Combined with additional merits including donor–acceptor pair to favor electron transfer and fluorescence quenching effect after NP formation, the photothermal conversion efficiency of the PPor‐PEG NPs is determined to be 62.3%, which is the highest value among reported polymer NPs. Moreover, the as‐prepared PPor‐PEG NP not only exhibits a remarkable cell‐killing ability but also achieves 100% tumor elimination, demonstrating its excellent photothermal therapeutic efficacy. Finally, the as‐prepared water‐dispersible PPor‐PEG NPs show good biocompatibility and biosafety, making them a promising candidate for future clinical applications in cancer theranostics.     

Robust Red Organic Nanoparticles for In Vivo Fluorescence Imaging of Cancer Cell Progression in Xenografted Zebrafish

Bright and red‐emissive organic nanoparticles (NPs) are demonstrated as promising for in vivo fluorescence imaging. However, most red organic dyes show greatly weakened or quenched emission in the aggregated state. In this work, a robust red fluorophore (t‐BPITBT‐TPE) with strong aggregate‐state photoluminescence and good biocompatibility is presented. The NPs comprised of t‐BPITBT‐TPE aggregates encapsulated within 1,2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine‐N‐[methoxy(polyethylene glycol) (DSPE‐mPEG) micelles exhibit a photoluminescence peak at 660 nm with a high fluorescence quantum yield of 32% in aqueous media. The NPs can be facilely charged by using the same polymeric matrix with different terminal groups, e.g., methoxy (DSPE‐mPEG), amine (DSPE‐PEG‐NH₂), or carboxymethyl (DSPE‐PEG‐COOH) groups. The biocompatibility, toxicity, circulation, and biodistribution of the NPs are assessed using the zebrafish model through whole embryo soaking and intravenous delivery. Furthermore, HeLa and MCF‐7 cells tagged with t‐BPITBT‐TPE in DSPE‐PEG‐NH₂‐TAT polymer NPs are xenografted into zebrafish larvae to successfully track the cancer cell proliferation and metastasis, demonstrating that these new NPs are efficient cancer cell trackers. In addition, the NPs also show good in vivo imaging ability toward 4T1 tumors in xenografted BALB/c mice.     

Self‐Organization and/or Nanocrystallinity of Co Nanocrystals Effects on the Oxidation Process Using High‐Energy Electron Beam

The enhanced stability of Co nanocrystals (NCs) when they are highly ordered at both nanometer and micrometer scales is reported. For the first time, it is shown that both the crystalline structure of Co nanoparticles (NPs) and their 2D hexagonal organization have a significant impact on the oxidation process rate enabling to produce various types of nanostructures including core‐shell NPs. The Co core can be either polycrystalline or hexagonal close‐packed (hcp) single‐crystalline, whereas the oxide shell is composed either of CoO or of the spinel structrure Co₃O₄. The present results are evidenced through a careful high‐resolution transmission electron microscopy (HRTEM) study and are highly reproducible.     

Hollow Two‐Layered Chiral Nanoparticles Consisting of Optically Active Helical Polymer/Silica: Preparation and Application for Enantioselective Crystallization

This article reports for the first time a novel category of hollow organic@inorganic hybrid two‐layered nanoparticles (NPs), in which the inner layer is formed by optically active helical polyacetylene, and the outer layer by silica. Such NPs show remarkable optical activity and are successfully used for enantioselective crystallization. To prepare such NPs, n‐butyl acrylate undergoes radical polymerization to first form poly(n‐butyl acrylate) (PBA) cores two shells by catalytic polymerization of substituted acetylene and sol–gel approach of TEOS (tetraethyl orthosilicate), respectively. Removal of the PBA cores provides the expected hollow core/shell NPs. The intense dircular dichroism (CD) effects demonstrate that the hollow chiral NPs possess considerable optical activity, arising from the helical substituted polyacetylenes forming the inner layer. The hollow NPs are further used as chiral templates to induce enantioselective crystallization of racemic alanines, demonstrating the significant potential applications of the hollow chiral NPs in chiral technologies. Also of particular significance is the detailed process of the induced crystallization observed by TEM. The strategy for preparing the hollow hybrid chiral NPs should be highlighted since it combines free radical polymerization and catalytic polymerization with sol–gel process in a single system, by which numerous advanced materials will be accessible.     

Polywraplex,Functionalized Polyplexes by Post‐Polyplexing Assembly of a Rationally Designed Triblock Copolymer Membrane

A core–shell structured synthetic carrier, polywraplex, is reported to overcome the hurdles along the inter‐ and intracellular pathways of systemic delivery of siRNA, yet remain structurally simple and easy‐to‐formulate. The core is a cationic polyplex formed of siRNA with polyethylene imine (PEI) and polyspermine‐imidazole‐4,5‐imine (PSI), respectively, and the shell is a self‐assembled unilamella membrane of PEG₄₅‐PCL₂₀‐mototriose‐COO^?, a triblock copolymer possessing multicarboxyl saccharide block to guide adsorption to each polyplex surface, a hydrophobic central block to form a protecting layer around the nucleic acid core, and a PEG block functioning as a steric stabilization out‐layer to extend in vivo circulation. The hydrophobic layer limits the anionic charges of the guiding block within a 2D surface to prevent them from penetrating into the polyplex, a common cause for prephagocytic siRNA leaking by polyelectrolytes in vivo. Cell targeting agents may be conjugated to the distal end of the PEG block and assembled on polyplex surface in optimal population. Chemical characterizations comprising consequent fluorescent imaging, dynamic laser scattering, zeta potential, as well as electrophoresis confirm polywraplex formation and its protection to siRNA against leaking and degradation in serum. Cellular and in vivo (mice) assays of biotin‐conjugated polywraplexes suggest prolonged circulation and tumor tissue targeting.     

Unusual Circularly Polarized Photocatalytic Activity in Nanogapped Gold–Silver Chiroplasmonic Nanostructures

Gold‐gap‐silver nanostructures (GGS NSs) with interior nanobridged gaps are enantioselectively fabricated. Guided by l/d ‐cysteine, the GGS‐L/D (L/D represents l/d ‐cysteine) NSs show reversed plasmon‐induced circular dichroism (CD) signals in the visible region. It is found that the nanogap plays a key role in the plasmonic CD of GGS NSs and the chiroptical response can be tailored by adjusting the amount of cysteine. The anisotropy factor of GGS‐L/D NSs with a 0.5 nm interior gap at 430 nm is as high as ≈0.01. The circularly polarized photocatalytic activity of GGS NSs is examined. It is shown that upon irradiation with left‐circularly polarized light, the catalytic efficiency of GGS‐L NSs is 73‐fold and 17‐fold higher than that of Au nanoparticles (NPs) and Au@Ag core–shell NPs, respectively. Upon irradiation with right‐circularly polarized light, the catalytic activity of GGS‐D NSs is about 71 times and 17 times higher than that of Au NPs and Au@Ag core–shell NPs, respectively. These unique chiral NSs with high plasmonic response can be applied to enantioselective catalysis.