Au Nanobipyramids Research Articles

Target Recognition-Triggered Interfacial Electron Transfer Model: Toward Signal-On Photoelectrochemical Aptasensing for Efficient Detection of Staphylococcus aureus Using Ti3C2Tx-Au NBPs/ZnO NR Composites.

Staphylococcus aureus (S. aureus) is one of the most common foodborne pathogens worldwide, which poses a great threat to public health. It is of utmost importance to develop rapid, simple, and sensitive methods for the determination of S. aureus. A signal-on photoelectrochemical (PEC) aptasensor is constructed herein based on titanium carbide (Ti3C2Tx)-Au nanobipyramids (NBPs)/ZnO nanoarrays (NRs). The reliability and capability of the PEC aptasensor make it suitable for the sensitive and selective determination of S. aureus. First, the electrostatically self-assembled Ti3C2Tx-Au NBP nanomaterial was coated on the ZnO NR surface by a spin-coating method. On the one hand, Ti3C2Tx-Au NBPs can broaden the spectral absorption of ZnO NRs, resulting in Ti3C2Tx-Au NBPs/ZnO NR composites that exhibit a wide range of absorption from the ultraviolet to the infrared region. On the other hand, Ti3C2Tx can reduce the agglomeration of nanoparticles, while Au NBPs can effectively fix the aptamer through the Au-S bond. Specifically, the experimental results show that when S. aureus is present, the Au NBPs-aptamer-S. aureus complex is shed from the electrode surface, altering the interfacial electron transfer model and reducing the steric hindrance. Consequently, an amplified photocurrent signal for the quantitative determination of S. aureus is obtained. Under optimal experimental conditions, a linear correlation is observed between the current response of the aptasensor and the logarithm of the S. aureus concentration (ranging from 1.0 to 1.0 × 106 CFU/mL), with an impressive detection limit as low as 0.5 CFU/mL. Furthermore, the aptasensor has been successfully employed for the detection of S. aureus in milk, with the recovery of 93.0%-99.0%. Hence, this research offers a novel approach for the detection of foodborne pathogens and other noxious substances.

Controlling the growth mode of Au depositing on Au nanobipyramids via ligand coverage for SERS enhancement

Gold deposition on Au nanoparticles is a common method to control the shape and further modify the properties of nanoparticles as their properties have a strong correlation with their nanostructures. For Au nanobipyramid (Au NBP), it has advantages such as the enhancement of electric field and a higher tunability in plasmon wavelength than the Au nanorod and thus owns a greater potential in shape control. In this paper, we demonstrate a scheme of depositing Au on the surface of Au NBP with the presence of a type of ligand 2-mercaptobenzoimidazole-5-carboxylic acid (MBIA) to synthesize Au NBP@Au dimers. The growth mode of Au depositing on Au NBP can be controlled by the coverage of MBIA. As the coverage is low, with a concentration of MBIA below 0.4 mM, the rough core–shell nanostructure is synthesized; However, as the coverage is high, with a concentration of MBIA over 0.8 mM, gold deposition may form islands on the surface of Au NBP. The SERS performance of Au depositing on Au NBP can also be enhanced by growth mode. For the rough-surface core–shell growth mode, the enhancement is more significant as the EF is improved from 3.5 × 105 to 1.06 × 106 than the islands-growing growth mode due to the coupling between core and shell. And our results show that with multiple types of nanosturctures easy to obtained by changing modified ligand coverage, the controlled growth has a great potential in the dimer design and SERS enhancement using Au NBP.

Simultaneous noninvasive ultrasensitive detection of prostate specific antigen and lncRNA PCA3 using multiplexed dual optical microfibers with strong plasmonic nanointerfaces

Low accuracy of diagnosing prostate cancer (PCa) was easily caused by only assaying single prostate specific antigen (PSA) biomarker. Although conventional reported methods for simultaneous detection of two specific PCa biomarkers could improve the diagnostic efficiency and accuracy, low detection sensitivity restrained their use in extreme early-stage PCa clinical assay applications. In order to overcome above drawbacks, this paper herein proposed a multiplexed dual optical microfibers separately functionalized with gold nanorods (GNRs) and Au nanobipyramids (Au NBPs) nanointerfaces with strong localized surface plasmon resonance (LSPR) effects. The sensors could simultaneously detect PSA protein biomarker and long noncoding RNA prostate cancer antigen 3 (lncRNA PCA3) with ultrahigh sensitivity and remarkable specificity. Consequently, the proposed dual optical microfibers multiplexed biosensors could detect the PSA protein and lncRNA PCA3 with ultra-low limit-of-detections (LODs) of 3.97 × 10−15 mol/L and 1.56 × 10−14 mol/L in pure phosphorus buffer solution (PBS), respectively, in which the obtained LODs were three orders of magnitude lower than existed state-of-the-art PCa assay technologies. Additionally, the sensors could discriminate target components from complicated physiological environment, that showing noticeable biosensing specificity of the sensors. With good performances of the sensors, they could successfully assay PSA and lncRNA PCA3 in undiluted human serum and urine simultaneously, respectively. Consequently, our proposed multiplexed sensors could real-time high-sensitivity simultaneously detect complicated human samples, that providing a novel valuable approach for the high-accurate diagnosis of early-stage PCa individuals.

In Situ Liquid Cell Transmission Electron Microscopy Observations of Growth and Anticorrosion Behaviors of AuCl3 Shell on Au Nanobipyramids

Comprehensive SummaryDesigning new materials and architectures to maintain activity and stability requires a better understanding on the anticorrosion dynamics of nanoparticles. Under‐coordinated atoms on the surface of nanoparticles can be protected by deposited shells. Real‐time observation on how protective shells grow and play a role is challenging but worthwhile. Here, protective effects of AuCl3 shells on Au nanobipyramids (NBPs) are studied in HAuCl4 aqueous solutions by in‐situ liquid cell transmission electron microscopy (LCTEM). This study is the first to observe the formation of Au‐AuCl3 core‐shell nanostructure and the corresponding anticorrosion behaviors of AuCl3 deposited shell. The presence of CTAB can substantially influence the growth mode and structure of AuCl3 shell, by a direct or indirect way, intervene the dissolution of Au NBP. These growth or dissolution kinetics here revealed at the nanoscale provide insights towards engineering of the surface anticorrosion to pursue Au nanoparticles with improved stability in acidic environment.

Ultrafast Hot‐Electron Transfer and Plasmonic Coupling Enable Au/MXene Nanohybrids with Broadband Excellent Nonlinear Absorption

AbstractAchieving coupling between plasma oscillators can significantly modulate their intrinsic optical characteristics. In this paper, strong coupling generated by the surface plasma of MXene and Au nanobipyramids (NBPs) for broadband ultrafast nonlinear optical modulation is reported. The femtosecond transient absorption spectra reveal that the ultrafast hot electron transfer occurred in the Au/MXene nanohybrids at <200 fs. Au/Ta4C3Tx nanohybrids outperform the outstanding broadband saturable absorption (SA), with a saturation intensity 106 times less than that of the initial MXene. Laser excitation at 1100 nm results in reverse saturable absorption for Ta4C3Tx nanosheets and a strong SA for Au/Ta4C3Tx nanohybrids, which extends the range of SA. Theoretical calculations indicate that excellent nonlinearity is synergistically achieved via hot electron transfer and plasmon coupling. Femtosecond transient absorption spectra reveal that Au NBPs offer the additional occupied state for carriers through the transfer process and extend the carrier lifetime considerably. This study provides theoretical guidance for the exploration of remarkable novel nonlinear‐active 2D layer‐based materials and candidates for the practical applications of saturable absorbers.

Symmetry-Breaking of Nanoparticle Surface Function Via Conformal DNA Design.

Asymmetric surface functionalization of complex nanoparticles to control their directional self-assembly remains a considerable challenge. Here, we demonstrated a conformal DNA design strategy for flexible remodeling of the surface of complex nanoparticles, taking Au nanobipyramids (AuNBPs) as a model. We sheathed one or both tips of AuNBPs into conformal DNA origami with an exceptionally accurate orientation control. Such asymmetrically and symmetrically distributed surface patches possess regioselective, sequence, and site-specific DNA binding capabilities. As a result, we realized a series of prototypical multicomponent "colloidal molecules" made of AuNBPs and Au nanospheres (AuNSs) with defined directionality and number of "bonding valence" as well as 1D and 3D hierarchical assemblies, e.g., inverse core-satellites of AuNBPs and AuNSs, side-by-side and tip-to-tip linear assemblies of AuNBPs, and 3D helical superstructures of AuNBPs with tunable twists. These findings inspire new opportunities for nanoparticle surface engineering and the high-order self-assembly of nanoarchitectures with higher complexity and broadened functionalities.

DMSO-mediated ag lateral coated Au nanobipyramids: Ultrafast colormetric detection platform for Fe3+ with uniform etching

Colorimetric detection by etching based on metal nanoparticles is one of the most commonly portable detection methods, but there are problems such as poor particle controllability and irregular etching. In this paper, a novel Ag lateral coated Au nanobipyramids nanostructure (Au@Ag LCNBPs) for multi-colorimetric detection of Fe3+ is prepared through the mediation of dimethyl sulfoxide (DMSO). When DMSO is used to cover the surface of Au nanobipyramids (Au NBPs), it greatly affects the way Ag coated Au NBPs. When the volume ratio of DMSO is 25%, Ag is no longer deposited at the tip, but gradually deposited on the side of the Au NBPs to form the Au@Ag LCNBPs. The long axis cross-section of the Au@Ag LCNBPs takes the shape of a hexagon. As the Ag content increases, the width of the Ag layer gradually increases, the cross-section gradually converts to a positive hexagonal shape, and the aspect ratio of the whole structure decreases, leading to the blueshift of the longitudinal LSPR peak. This mode of deposition is different from the longitudinal deposition reported in the previous literature. A multi-colorimetric detection method for Fe3+ using the etching of the Ag layer by Au@Ag LCNBPs has been developed. This method exhibits a good exponential correlation in the concentration range of 1–210 μM with the detection limit of 200 nM. With the increase of Fe3+, the colloid color shows the change of yellow, orange, red, purple, blue, green and colorless. The etching process can be completed in about 30 s. This nanostructure achieves two etching modes of the Ag layer by Fe3+, uniform etching and concave etching. Moreover, it demonstrates that the enormous potential of Au@Ag LCNBPs in colorimetric etching detection.

Macroscopic Superlattice Membranes Self-Assembled from Gold Nanobipyramids with Precisely Tunable Tip Arrangements for SERS.

A persistent challenge in utilizing Au nanocrystals for surface-enhanced Raman spectroscopy (SERS) lies in achieving controllable superstructures that maximize SERS performance. Here, a novel strategy is proposed to enhance the SERS performance by precisely adjusting the tip arrangements of Au nanobipyramids (BPs) in two-dimensional (2D) superlattices (SLs). This is achieved through ligand-exchange of Au BPs, followed by liquid-air interfacial assembly, resulting in large-area, transferrable SL membranes. The key to controlling the arrangement of Au BPs in the SLs is the regulation of the amount of free ligands added during self-assembly, which allows for the precise formation of various configurations such as tilted SLs, tip-on-tip SLs, and tip-to-tip SLs. Among these configurations, tip-on-tip SLs exhibit the highest enhancement factor for SERS, reaching an impressive value of 1.95×108, with uniform and consistent SERS signals across a large area. The experimental findings are further corroborated by simulations using the finite element method. This study establishes an efficient method for engineering the microstructure of 2D SLs composed of Au BPs, highlighting the importance of fine-tuning the tip arrangements of Au BPs to regulate SERS performance.

Macroscopic Superlattice Membranes Self‐Assembled from Gold Nanobipyramids with Precisely Tunable Tip Arrangements for SERS

AbstractA persistent challenge in utilizing Au nanocrystals for surface‐enhanced Raman spectroscopy (SERS) lies in achieving controllable superstructures that maximize SERS performance. Here, a novel strategy is proposed to enhance the SERS performance by precisely adjusting the tip arrangements of Au nanobipyramids (BPs) in two‐dimensional (2D) superlattices (SLs). This is achieved through ligand‐exchange of Au BPs, followed by liquid‐air interfacial assembly, resulting in large‐area, transferrable SL membranes. The key to controlling the arrangement of Au BPs in the SLs is the regulation of the amount of free ligands added during self‐assembly, which allows for the precise formation of various configurations such as tilted SLs, tip‐on‐tip SLs, and tip‐to‐tip SLs. Among these configurations, tip‐on‐tip SLs exhibit the highest enhancement factor for SERS, reaching an impressive value of 1.95×108, with uniform and consistent SERS signals across a large area. The experimental findings are further corroborated by simulations using the finite element method. This study establishes an efficient method for engineering the microstructure of 2D SLs composed of Au BPs, highlighting the importance of fine‐tuning the tip arrangements of Au BPs to regulate SERS performance.

Construction of Gold/Rhodium Freestanding Superstructures as Antenna-Reactor Photocatalysts for Plasmon-Driven Nitrogen Fixation.

Precisely controlling the architecture and spatial arrangement of plasmonic heterostructures offers unique opportunities to tailor the catalytic property, whereas the lack of a wet-chemistry synthetic approach to fabricating nanostructures with high-index facets limits their practical applications. Herein, we describe a universal synthetic strategy to construct Au/Rh freestanding superstructures (SSs) through the selective growth of ordered Rh nanoarrays on high-index-faceted Au nanobipyramids (NBPs). This synthetic strategy works on various metal nanocrystal substrates and can yield diverse Au/Rh and Pd/Rh SSs. Especially, the obtained Au NBP/Rh SSs exhibit high photocatalytic activity toward N2 fixation as a result of the spatially separated architecture, local electric field enhancement, and the antenna-reactor mechanism. Both theoretical and experimental results reveal that the Au NBPs can function as nanoantennas for light-harvesting to generate hot charge carriers for driving N2 fixation, while the Rh nanoarrays can serve as the active sites for N2 adsorption and activation to synergistically promote the overall catalytic activity in the Au NBP/Rh SSs. This work offers new avenues to rationally designing and constructing spatially separated plasmonic photocatalysts for high-efficiency catalytic applications.

Identification and classification of ATS in oral fluid based on Ag nanoassemblies on Si surface doped with Au nanobipyramids

Herein, a novel Ag NP substrate doped with Au nanobipyramids was designed and fabricated via a convenient procedure of galvanic reaction for the identification and classification of amphetamine-type stimulants (ATS) in oral fluids in combination with surface enhanced Raman scattering (SERS). The substrate was shown to have a three-dimensional nanostructure, high SERS activity, and good stability. In combination with SERS, the Ag NP substrate doped with Au nanobipyramids was able to detect ultra-low traces of ATS, including amphetamine, methylamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA), and 3,4-methylenedioxymethylamphetamine (MDMA) in oral fluid with limit of detection (LOD) and limit of determination quantitation (LOQ) as low as 10–9 mg/mL, which is much better than the current spectroscopic techniques. The equations between concentration and peaks intensity for quantitative analysis displied good doublelogarithmic linear relations and reliability figures of merit at nanogram concentration level in compartion with GC–MS method. The approach can be broadly applied to the ultra-low trace detection of ATS in oral fluid and would be particularly useful for the analyses of nitrogenous organic compounds.

Engineering Dumbbell-Shaped Au Nanobipyramid/Ag-CeO2 Plasmonic Bimetal-Semiconductor Heterostructures for Nitroaromatic Reduction

Precisely engineering the morphology of plasmonic metal–semiconductor heterostructures (PMSHs) is essential for fully utilizing the localized surface plasmon resonance (LSPR) function. However, most of the PMSHs mainly depend on the LSPR contribution of a single plasmonic metal, while the bimetal semiconductor heterostructures have been rarely reported. Herein, a series of dumbbell-shaped bimetal semiconductor heterostructures, based on Au nanobipyramids (AuNBPs, average length of 96 ± 3 nm, waist diameter of 29 ± 3 nm), lateral surfaces covered with rice-shaped Ag layers (thickness less than 5 nm), and a tip loaded with cap-shaped CeO2 (average size of 44 nm), were engineered. By simply tuning the dose of Ag+ and CTAC, we can precisely engineer the morphology of PMSHs from dumbbell-shaped monometal semiconductors (AuNBP–CeO2) to a core/shell/shell structure (AuNBP@Ag@CeO2) and to the dumbbell-shaped bimetal semiconductor AuNBP/Ag–CeO2. Notably, the AuNBP/Ag–CeO2 nanostructure exhibits higher activity in photocatalytic nitroreduction of 4-NP than AuNBP–CeO2. Mechanism analysis demonstrated that the bimetal semiconductor dumbbell-shaped AuNBP/Ag–CeO2 shows stronger electromagnetic field enhancement than the monometal semiconductor dumbbell-shaped AuNBP–CeO2, which promotes the generation of hot electrons more efficiently. This work offers an insight into precisely engineering plasmonic bimetallic semiconductor heterostructures for photocatalytic applications.

Gold-Based Nanostructures for Antibacterial Application.

Bacterial infections have become a fatal threat because of the abuse of antibiotics in the world. Various gold (Au)-based nanostructures have been extensively explored as antibacterial agents to combat bacterial infections based on their remarkable chemical and physical characteristics. Many Au-based nanostructures have been designed and their antibacterial activities and mechanisms have been further examined and demonstrated. In this review, we collected and summarized current developments of antibacterial agents of Au-based nanostructures, including Au nanoparticles (AuNPs), Au nanoclusters (AuNCs), Au nanorods (AuNRs), Au nanobipyramids (AuNBPs), and Au nanostars (AuNSs) according to their shapes, sizes, and surface modifications. The rational designs and antibacterial mechanisms of these Au-based nanostructures are further discussed. With the developments of Au-based nanostructures as novel antibacterial agents, we also provide perspectives, challenges, and opportunities for future practical clinical applications.

Fluorescence enhancement of surface plasmon coupled emission by Au nanobipyramids and its modulation effect on multi-wavelength radiation

Surface plasmon coupled emission (SPCE), a novel surface-enhanced fluorescence technique, can generate directional and amplified radiation by the intense interaction between fluorophores and surface plasmons (SPs) of metallic nanofilms. For plasmon-based optical systems, the strong interaction between localized and propagating SPs and “hot spot” structures show great potential to significantly improve the electromagnetic (EM) field and modulate optical properties. Au nanobipyramids (NBPs) with two sharp apexes to enhance and restrict the EM field were introduced through electrostatic adsorption to achieve a mediated fluorescence system, and the emission signal enhancement was realized by factors over 60 compared with the normal SPCE. It has been demonstrated that the intense EM field produced by the NBPs assembly is what triggered the unique enhancement of SPCE by Au NBPs, which effectively overcomes the inherent signal quenching of SPCE for ultrathin sample detection. This remarkable enhanced strategy offers the chance to improve the detection sensitivity for plasmon-based biosensing and detection systems, and expand the range of applications for SPCE in bioimaging with more comprehensive and detailed information acquisition. The enhancement efficiency for various emission wavelengths was investigated in light of the wavelength resolution of SPCE, and it was discovered that enhanced emission for multi-wavelength could be successfully detected through the different emission angles due to the angular displacement caused by wavelength change. Benefit from this, the Au NBP modulated SPCE system was employed for multi-wavelength simultaneous enhancement detection under a single collection angle, which could broaden the application of SPCE in simultaneous sensing and imaging for multi-analytes, and expected to be used for high throughput detection of multi-component analysis.

Rebuildable Silver Nanoparticles Employed as Seeds for Synthesis of Pure Silver Nanopillars with Hexagonal Cross-Sections under Room Temperature

Silver nanopillars with strong plasmonic effects are used for localized electromagnetic field enhancement and regulation and have wide potential applications in sensing, bioimaging, and surface-enhanced spectroscopy. Normally, the controlled synthesis of silver nanopillars is mainly achieved using heterometallic nanoparticles, including Au nanobipyramids and Pd decahedra, as seeds for inducing nanostructure growth. However, the seed materials are usually doped in silver nanopillar products. Herein, the synthesis of pure silver nanopillars with hexagonal cross-sections is achieved by employing rebuildable silver nanoparticles as seeds. An environmentally friendly, stable, and reproducible synthetic route for obtaining silver nanopillars is proposed using sodium dodecyl sulfate as the surface stabilizer. Furthermore, the seed particles induce the formation of regular structures at different temperatures, and, specifically, room temperature is beneficial for the growth of nanopillars. The availability of silver nanoparticle seeds using sodium alginate as a carrier at different temperatures was verified. A reproducible method was developed to synthesize pure silver nanopillars from silver nanoparticles at room temperature, which can provide a strategy for designing plasmonic nanostructures for chemical and biological applications.

High aspect ratio plasmonic Au/Ag nanorods-mediated NIR-II photothermally enhanced nanozyme catalytic cancer therapy

Chemodynamic therapy (CDT) is based on the endogenous generation of cytotoxic hydroxyl free radicals (·OH) with high specificity and selectivity between cancer and normal cells. However, its efficacy is often limited by the relatively deficient catalytic activity of nanozymes in the tumor microenvironment (TME). Therefore, the combination of CDT with other strategy to realize synergistic therapy is necessary. Herein, a versatile plasmonic Au/Ag nanorods (abbreviated as Au/Ag NRs) via anisotropic Ag overgrowth on Au nanobipyramids was rationally devised to achieve synergistic nanozyme catalytic therapy and near infrared II (NIR-II) light induced photothermal therapy (PTT) with the guidance of computed tomography (CT) imaging. As TME contains high concentrations of H+ and H2O2, Au/Ag NRs exhibited peroxidase (POD) activity to catalyze H2O2 to produce ·OH, inducing cancer cell death. Meanwhile, Au/Ag NRs showed a preeminent NIR-II photothermal effect. More importantly, the enhanced ·OH generation by in-situ heating up resulting from PTT could conversely inhibit the expression of heat shock proteins (HSPs) to abate their resistance to PTT, realizing self-augmented synergistic effect. The NIR-II photothermally enhanced nanozyme catalytic cancer therapy validly inhibited the cancer proliferation, as demonstrated via both cell and animal assays. Moreover, ideal high-contrast CT imaging was realized, owing to the X-ray attenuation capability of elemental Au. The multifunctional Au/Ag NRs hold potential in oncotherapy with imaging capability, high efficiency and low side effects.

Sensitive detection of extracellular hydrogen peroxide using plasmon-enhanced electrochemical activity on Pd-tipped Au nanobipyramids.

The fabrication of electroactive nanostructures with high electron concentration and specific electron transport is crucial for electrochemical sensing. In this study, a plasmon-enhanced electrochemical sensor has been developed for the detection of extracellular hydrogen peroxide (H2O2) from cancer cells, utilizing Pd-tipped Au nanobipyramids (PTA NBPs) as the electrocatalysts. Plasmonic PTA NBPs were synthesized by depositing Pd nanoparticles onto the tips of Au nanobipyramids (Au NBPs). Under excitation of localized surface plasmon resonance (LSPR), the PTA NBPs generate high-energy electron-hole pairs (e-/h+) on their surface. The generated electrons (e-) significantly enhance the electrochemical reduction of H2O2. Based on this, a plasmon-enhanced H2O2 electrochemical sensor is constructed with high sensitivity (986.57 μA mM-1 cm-2), low detection limit (0.02 μM), wide linear range (0.1 μM to 980 μM), and good stability and repeatability. Moreover, this sensor also enables the measurement of extracellular H2O2 derived from cancer cells (MCF-7), highlighting its potential applications in cellular biology and biomedical research.

Self-Assembled MXene-Au Multifunctional Nanomaterials with Various Shapes for Label-free SERS Detection of Pathogenic Bacteria and Photothermal Sterilization.

Early diagnosis of pathogenic bacteria and treatment are essential to prevent further infection. Photothermal therapy (PTT) is a promising sterilization method with advantages of minimal invasiveness and high efficiency. The effect of PTT depends on the performance of photothermal materials. Herein, Ti3C2-Au nanomaterials were prepared by the electrostatic self-assembly method, and the absorption characteristics were modulated by changing the morphology of Ti3C2-Au to achieve high photothermal conversion efficiency and sensitive label-free SERS bacterial detection. The results showed that the prepared Ti3C2-Au had better SERS performance than Au and achieved direct and sensitive detection of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Under 808 nm laser irradiation, the photothermal conversion efficiency of Ti3C2-Au nanobipyramids (NBPs) was increased to 50.41% compared with the other two composites. The bactericidal rates of Ti3C2-Au NBPs against E. coli and S. aureus were 95.11 and 99.80% in 8 min, respectively, and the killing rates of nine other bacteria were all above 95%, showing broad-spectrum antibacterial properties. Cell viability studies showed that the Ti3C2-Au NBP had significantly improved biocompatibility compared with the Au NBP and was suitable for biological applications. It can simultaneously realize sensitive bacterial detection and photothermal sterilization and is important for the detection and inhibition of pathogenic bacteria.

Tumor microenvironment responsive-multifunctional nanocomposites knotted injectable hydrogels for enhanced synergistic chemodynamic and chemo-photothermal therapies

Multifunctional nanomedicine has offered a promising strategy for effective anticancer therapy owing to its versatile capabilities. However, the systematic precise delivery still remains intractable challenge because of the existence of multi-staged biological barriers after intravenous administration. Herein, to address this issue, injectable and TME-responsive nanocomposite hydrogels were developed for localized and synergistic cancer therapy. The nanocomposite hydrogels (Au NBPs&Pt NCs@DOX gel) were synthesized via the formation of metal-sulfur bonds between 4arm-PEG-thiol and Au nanobipyramids or Pt nanoclusters with the DOX encapsulation. The hydrogel exhibited rapid gelation and excellent injectability. Attributed to the high absorbance of Au NBPs, the nanocomposite hydrogels revealed superior photothermal effect under NIR irradiation, which the DOX release was also regulated by NIR laser. In addition, the catalase- and peroxidase-like activities of Pt NCs were validated to convert endogenous H2O2 into ROS and O2 in situ to achieve chemodynamic therapy (CDT) and alleviate the hypoxic microenvironment. Simultaneously, catalytic therapy combined with NIR irradiation exhibited strongest inhibition to the growth of 4T1 tumor in vitro and in vivo. Thus, this study provided a new strategy for TME remodeling and local combination therapies of different therapeutic agents.

Tipping Gold Nanobipyramids with Titania for the Use of Plasmonic Hotspots to Drive Amine Coupling.

Designing plasmonic photocatalysts with spatially controlled catalytic sites is an effective strategy to boost the sunlight-driven chemical transformation efficiency through plasmonic enhancement. Herein, we describe a facile method for the synthesis of TiO2-tipped Au nanobipyramids (NBPs) to give (Au NBP)/t-TiO2 nanodumbbells. The surfactant cetyltrimethylammonium bromide concentration is the key factor in the construction of this type of unique nanostructure. The photocatalytic aerobic oxidative coupling of amines using the plasmonic photocatalysts with the dumbbell-like and core@shell structures indicates that the TiO2-tipped ends for the photo-reduction and the exposed adjacent Au surface for the photo-oxidation on (Au NBP)/t-TiO2 can significantly improve the photocatalytic activity. The underlying mechanism of the photocatalytic oxidative coupling of benzylamine over (Au NBP)/t-TiO2 has been thoroughly investigated. Both experimental and simulation results for (Au NBP)/t-TiO2 and (Au nanorod)/t-TiO2 confirm the important effect of the plasmonic hotspots on the enhancement of the photocatalytic activity.