Improved size-tunable synthesis of monodisperse gold nanorods through the use of aromatic additives

Seedless preparation of Au nanorods by hydroquinone assistant and red blood cell membrane camouflage

Natural red blood cell membranes camouflaged Au nanorod composites that exhibited an excellent biocompatibility and photothermal ablation effect.

Seed-mediated growth of Au@Ag core-shell nanorods for the detection of ellagic acid in whitening cosmetics

Seed-mediated growth has been employed as a simple and powerful means to the shape-controlled synthesis of metal nanocrystals. In this work, we apply the principle of seed-mediated growth in analytical chemistry, and achieve improved sensitivity due to the low energy barrier in the target-induced formation of bimetallic nanoparticles with core-shell structure. As a result, a simple, reliable, highly sensitive and selective method for the detection of ellagic acid (EA), a naturally occurring polyphenolic antioxidant, has been developed. With the aid of EA in alkaline solution, Ag⁺ ions can be transformed to Ag atoms and deposit on the surfaces of Au nanorods (AuNRs, act as seeds here) to generate Au@Ag core-shell nanorods, accompanied by blue shift of the longitudinal localized surface plasmon resonance (LSPR) band of AuNRs from near-infrared region to shorter wavelengths. Based on the linear relationship between the wavelength change of longitudinal LSPR band and the concentration of EA, our method achieves a detectable range of 0.2-20 μM and a limit of detection as low as 40 nM toward EA. This approach is highlighted by its high sensitivity for EA assay, which benefits from the viewpoint of thermodynamics in the nucleation/growth mode of metal nanoparticles. Moreover, this method shows high selectivity for EA detection when potential species coexist, and thus has been successfully applied in the detection of EA in skin-whitening cosmetics. The proposed strategy of seed-mediated growth herein can also be extended to other systems for sensing.

Gold nanoshurikens with uniform sharp tips for chemical sensing by the localized surface plasmon resonance

Creation of uniform sharp tips in noble metal nanostructures is highly desirable for chemical sensing applications that rely on their localized surface plasmon resonance (LSPR), while it remains a great challenge as typically it is not energetically favorable. Herein, we report a robust synthesis route to a novel family of unique shuriken-shaped Au nanostructures with four in-plane sharp tips in high yield and uniformity. The success of the synthesis relies on the anisotropic crystal growth of quasi-planar Au seeds by taking advantage of the capping effect of a ligand on the specific facets, as well as the predominant deposition of Au over its surface diffusion that accounts for the formation of the sharp tips. The resulting Au nanoshurikens show remarkable LSPR in the near-infrared range of the spectrum, which proves to be sensitive to a minor change in the sharp tips, thus enabling superior chemical sensing activity, as demonstrated by detection of mercury of ultralow concentrations. This novel nanostructure promises not only great potential in monitoring mercury in aquatic ecosystems, but also wide applicability to many other sensing scenarios, such as analyzing various chemicals and biologically active species, with excellent sensitivity.

Accelerating Gold Nanorod Synthesis with Nanomolar Concentrations of Poly(vinylpyrrolidone)

A novel modification for the seedless synthesis of gold nanorods (AuNRs) has been developed. Nanomolar concentrations of 10 kDa poly(vinylpyrrolidone) (PVP) can be introduced to a growth solution containing 25, 50, or 100 mM cetyltrimethylammonium bromide (CTAB) to significantly reduce the dimensions of AuNRs. We found that PVP accelerates the growth rate of AuNRs by more than two times that of nanorods grown in 50 and 100 mM CTAB solutions. Additionally, there is a time-dependent effect of adding PVP to the nanorod growth solution that can be utilized to tune their aspect ratio. Because the concentration of PVP is far below the concentration of HAuCl₄ in the reaction mixture, PVP primarily functions not as a reducing agent, but as a capping or templating ligand to stabilize the growing nanorods. Our reproducible protocol enables the synthesis of AuNRs in high yield with tunable sizes: 45 × 6.7, 28 × 5.5, and 12 × 4.5 nm for 100, 50, and 25 mM CTAB, respectively. We estimated the number of PVP chains per nanorod in growth solutions to be around 30, which suggests that the effect on the aspect ratio is caused by a direct interaction between the AuNR surface and the PVP.

Accuracy and Mechanistic Details of Optical Printing of Single Au and Ag Nanoparticles

Optical printing is a powerful all-optical method that allows the incorporation of colloidal nanoparticles (NPs) onto substrates with nanometric precision. Here, we present a systematic study of the accuracy of optical printing of Au and Ag NPs, using different laser powers and wavelengths. When using light of wavelength tuned to the localized surface plasmon resonance (LSPR) of the NPs, the accuracy improves as the laser power is reduced, whereas for wavelengths off the LSPR, the accuracy is independent of the laser power. Complementary studies of the printing times of the NPs reveal the roles of Brownian and deterministic motion. Calculated trajectories of the NPs, taking into account the interplay between optical forces, electrostatic forces, and Brownian motion, allowed us to rationalize the experimental results and gain a detailed insight into the mechanism of the printing process. A clear framework is laid out for future optimizations of optical printing and optical manipulation of NPs near substrates.

Plasmonic gold nanostars as optical nano-additives for injection molded polymer composites

Nanoscale engineering of noble metal particles has provided numerous material configurations to selectively confine and manipulate light across the electromagnetic spectrum. Transitioning these materials to a composite form while maintaining the desired resonance properties has proven challenging. In this work, the successful integration of plasmon-focusing gold nanostars (GNSs) into polymer nanocomposites (PNCs) is demonstrated. Tailored GNSs are produced with over a 90% yield and methods to control the branching structures are shown. A protective silica capping shell is employed on the nanomaterials to facilitate survivability in the high temperate/high shear processing parameters to create optically-tuned injection molded PNCs. The developed GNS PNCs possess dichroic scattering and absorption behavior, opening up potential applications in the fields of holographic imaging, optical filtering and photovoltaics.

Ultrasensitive MicroRNA Assay via Surface Plasmon Resonance Responses of Au@Ag Nanorods Etching

Quantification of trace serum circulate microRNAs is extremely important in clinical diagnosis but remains a great challenge. Herein we developed an ultrasensitive platform for microRNA 141 (miR-141) detection based on a silver coated gold nanorods (Au@Ag NRs) etching process accompanied by surface plasmon resonance (SPR) shift. Both SPR absorption and scattering responses were monitored. Combined amplification cascades of catalyzed hairpin assembly (CHA) and hybridization chain reaction (HCR) with the sensitive SPR responses of plasmonic Au@Ag NRs, the proposed bioassay exhibited ultrahigh sensitivity toward miRNA-141 with dynamic range from 5.0 × 10^-17 M to 1.0 × 10^-11 M. With target concentration higher than 1.0 × 10^-13 M, the color of the solution changed obviously that could be observed with naked eyes. Under dark-field microscopy observation of individual particle, a limit of detection down to 50 aM could be achieved. Owing to the superior sensitivity and selectivity, the proposed method was applied to detecting trace microRNA in serum. Similar SPR assays could be developed simply by redesigning the switching aptamer for the detections of other microRNAs or targets such as small molecule, DNA, or protein. Considering the convenient operation, good performance and simple observation modes of this method, it may have great potential in trace bioanalysis for clinical applications.

Understanding and Reducing Photothermal Forces for the Fabrication of Au Nanoparticle Dimers by Optical Printing

Optical printing holds great potential to enable the use of the vast variety of colloidal nanoparticles (NPs) in nano- and microdevices and circuits. By means of optical forces, it enables the direct assembly of NPs, one by one, onto specific positions of solid surfaces with great flexibility of pattern design and no need of previous surface patterning. However, for unclear causes it was not possible to print identical NPs closer to each other than 300 nm. Here, we show that the repulsion restricting the optical printing of close by NPs arises from light absorption by the printed NPs and subsequent local heating. By optimizing heat dissipation, it is possible to reduce the minimum separation between NPs. Using a reduced graphene oxide layer on a sapphire substrate, we demonstrate for the first time the optical printing of Au-Au NP dimers. Modeling the experiments considering optical, thermophoretic, and thermo-osmotic forces we obtain a detailed understanding and a clear pathway for the optical printing fabrication of complex nano structures and circuits based on connected colloidal NPs.

Controlled deposition of palladium nanodendrites on the tips of gold nanorods and their enhanced catalytic activity

Plasmonic Au-Pd nanostructures have drawn significant attention for use in heterogeneous catalysis. In this study, palladium nanodendrite-tipped gold nanorods (PdND-T-AuNRs) were subjected to a facile fabrication under mild reaction conditions. The palladium amounts on the two tips were tunable. In the preparation of PdND-T-AuNRs, dense capped AuNRs, a low reaction temperature, and suitable stabilizing agents were identified as critical reaction parameters for controlling palladium nanodendrites deposited on both ends of AuNRs. After overgrowth with palladium nanodendrites, the longitudinal surface plasmonic resonance peaks of PdND-T-AuNRs were red-shifted from 810 nm to 980 nm. The electrocatalytic activity of PdND-T-AuNRs for ethanol oxidation was examined, which was a bit weaker than that of cuboid core-shell Au-Pd nanodendrites; however, PdND-T-AuNRs were more stable in ethanol electrooxidation. Moreover, the photocatalytic activity of PdND-T-AuNRs for Suzuki cross-coupling reactions was investigated. At room temperature, nearly 100% yield was obtained under laser irradiation. The results can further enhance our capability of fine-tuning the optical, electronic, and catalytic properties of the bimetallic Au-Pd nanostructures.

Colorimetric Fingerprints of Gold Nanorods for Discriminating Catecholamine Neurotransmitters in Urine Samples

Catecholamine neurotransmitters, generally including dopamine (DA), epinephrine (EP) and norepinephrine (NE) are known as substantial indicators of various neurological diseases. Simultaneous detection of these compounds and their metabolites is highly recommended in early clinical diagnosis. To this aim, in the present contribution, a high performance colorimetric sensor array has been proposed for the detection and discrimination of catecholamines based on their reducing ability to deposit silver on the surface of gold nanorods (AuNRs). The amassed silver nanoshell led to a blue shift in the longitudinal localized surface plasmon resonance (LSPR) peak of AuNRs, creating a unique pattern for each of the neurotransmitters. Hierarchical cluster analysis (HCA) and linear discriminate analysis (LDA) pattern recognition techniques were employed to identify DA, EP and NE. The proposed colorimetric array is able to differentiate among individual neurotransmitters as well as their mixtures, successfully. Finally, it was shown that the sensor array can identify these neurotransmitters in human urine samples.

Highly Concentrated Seed-Mediated Synthesis of Monodispersed Gold Nanorods

The extremely large optical extinction coefficient of gold nanorods (Au-NRs) enables their use in a diverse array of technologies, rnging from plasmonic imaging, therapeutics and sensors, to large area coatings, filters, and optical attenuators. Development of the latter technologies has been hindered by the lack of cost-effective, large volume production. This is due in part to the low reactant concentration required for symmetry breaking in conventional seed-mediated synthesis. Direct scale up of laboratory procedures has limited viability because of excessive solvent volume, exhaustive postsynthesis purification processes, and the generation of large amounts of waste (e.g., hexadecyltrimethylammonium bromide(CTAB)). Following recent insights into the growth mechanism of Au-NRs and the role of seed development, we modify the classic seed-mediated synthesis via temporal control of seed and reactant concentration to demonstrate production of Au-NRs at more than 100-times the conventional concentration, while maintaining independent control and narrow distribution of nanoparticle dimensions, aspect ratio, and volume. Thus, gram scale synthesis of Au-NRs with prescribed aspect ratio and volume is feasible in a 100 mL reactor with 1/100th of organic waste relative to conventional approaches. Such scale-up techniques are crucial to cost-effectively meet the increased demand for large quantities of Au-NRs in emerging applications.

Harnessing Hot Electrons from Near IR Light for Hydrogen Production Using Pt-End-Capped-AuNRs

Gold nanorods show great potential in harvesting natural sunlight and generating hot charge carriers that can be employed to produce electrical or chemical energies. We show that photochemical reduction of Pt(IV) to Pt metal mainly takes place at the ends of gold nanorods (AuNRs), suggesting photon-induced hot electrons are localized in a time-averaged manner at AuNR ends. To use these hot electrons efficiently, a novel synthetic method to selectively overgrow Pt at the ends of AuNRs has been developed. These Pt-end-capped AuNRs show relatively high activity for the production of hydrogen gas using artificial white light, natural sunlight, and more importantly, near IR light at 976 nm. Tuning of the surface plasmon resonance (SPR) wavelength of AuNRs changes the hydrogen gas production rate, indicating that SPR is involved in hot electron generation and photoreduction of hydrogen ions. This study shows that gold nanorods are excellent for converting low-energy photons into high-energy hot electrons, which can be used to drive chemical reactions at their surfaces.

Rapid Large-Scale Assembly and Pattern Transfer of One-Dimensional Gold Nanorod Superstructures

The utility of gold nanorods for plasmonic applications largely depends on the relative orientation and proximity of the nanorods. Though side-by-side or chainlike nanorod morphologies have been previously demonstrated, a simple reliable method to obtain high-yield oriented gold nanorod assemblies remains a significant challenge. We present a facile, scalable approach which exploits meniscus drag, evaporative self-assembly, and van der Waals interactions to precisely position and orient gold nanorods over macroscopic areas of 1D nanostructured substrates. By adjusting the ratio of the nanorod diameter to the width of the nanochannels, we demonstrate the formation of two highly desired translationally ordered nanorod patterns. We further demonstrate a method to transfer the aligned nanorods into a polymer matrix which exhibits anisotropic optical properties, allowing for rapid fabrication and deployment of flexible optical and electronic materials in future nanoscale devices.

Towards a classification strategy for complex nanostructures

The range of possible nanostructures is so large and continuously growing, that collating and unifying the knowledge connected to them, including their biological activity, is a major challenge. Here we discuss a concept that is based on the connection of microscopic features of the nanomaterials to their biological impacts. We also consider what would be necessary to identify the features that control their biological interactions, and make them resemble each other in a biological context.

Photocatalytic activities and photoinduced fusion of gold-modified titania nanoparticle

Gold nanoparticles measuring 3–30 nm deposited on semiconductors result in an effective photocatalyst against several pollutants. Its photocatalytic activities are significant under both UV and solar irradiation. In a photocatalytic system, the oxidation of pollutants takes place on the gold surface as the electron donor, while the electron is consumed by the reduction of oxygen as the electron acceptor on the semiconductor’s surface. This promotes not only increased photocatalytic activities but also the green transformation of pollutant compounds to harmless compounds. The photosensitivity of semiconductors can be modified by tuning the size, shape, and contact of gold nanoparticles. This review highlights the function of gold nanoparticles in overcoming the limitation of transition metal oxide materials in photocatalytic applications.

Quenching of R6G Fluorescence by Gold Nanoparticles of Various Particle Geometries

The quenching of Rhodamine 6G in aqueous solution by citrate stabilized gold nanoparticles differing in their geometry (spheres, rods, prisms) was investigated. Static quenching was observed throughout. At constant surface area, the quenching rate diminished in the order spheres>rods>prisms. The effect is shown to be due to differing nanoparticle volumes rather than to variations in the surface area.

Systematic study of interdependent relationship on gold nanorod synthesis assisted by electron microscopy image analysis

Here, we systematically investigated the independent, multiple, and synergic effects of three major components, namely, ascorbic acid (AA), seed, and silver ions (Ag⁺), on the characteristics of gold nanorods (GNRs), i.e., longitudinal localized surface plasmon resonance (LSPR) peak position, shape, size, and monodispersity. To quantitatively assess the shape and dimensions of GNRs, we used an automated transmission electron microscopy image analysis method using a MATLAB-based code developed in-house and the concept of solidity, which is the ratio between the area of a GNR and the area of its convex hull. The solidity of a straight GNR is close to 1, while it decreases for both dumbbell- and dogbone-shaped GNRs. We found that the LSPR peak position, shape, and monodispersity of the GNRs all altered simultaneously with changes in the amounts of individual components. For example, as the amount of AA increased, both the LSPR peak and solidity decreased, while the polydispersity increased. In contrast, as the amount of seeds increased, both the LSPR and solidity increased, while the monodispersity improved. More importantly, we found that the influence of each component can actually change depending on the composition of the GNR growth solution. For instance, the LSPR peak position red-shifted as the amount of AA increased when the seed content was low, whereas it blue-shifted when the seed content was high.

Polymorphic Assembly from Beveled Gold Triangular Nanoprisms

The shape anisotropy of nanoparticle building blocks is of critical importance in determining their packing symmetry and assembly directionality. While there has been extensive research on the effect of their overall geometric shapes, the importance of nanometer morphology details is not well-recognized or understood. Here we draw on shape-anisotropic gold triangular nanoprism building blocks synthesized based on a method we recently developed; besides the "large-scale" triangular prism shape (79.8 nm in side length and 22.0 nm in thickness), the prisms are beveled with their sides convexly enclosed by two flat {100} facets. We engineer the balance between electrostatic repulsion and entropically driven depletion attraction in the system to generate self-assemblies without or with the effect of the nanoscale beveling detail. A conventional, planar honeycomb (p-honeycomb) lattice forms with the triangular basal planes packed on the same plane at low depletion attraction, whereas an unexpected interlocking honeycomb (i-honeycomb) lattice and its "supracrystal" forms are assembled with additional close-paralleling of side facets at high depletion attraction. The i-honeycomb lattice renders all the metallic surfaces in close proximity and leads to a surface-enhanced Raman scattering signal nearly 5-fold higher than that in the p-honeycomb lattice and high sensitivity for detecting the model molecule Rhodamine 6G at a concentration as low as 10^-8 M. Our study can guide future work in both nanoparticle synthesis and self-assembly; nanoscale geometrical features in anisotropic nanoparticles can be used as an important handle to control directional interactions for nonconventional ordered assemblies and to enrich diversity in self-assembly structure and function.

Towards clinically translatable in vivo nanodiagnostics

Nanodiagnostics as a field makes use of fundamental advances in nanobiotechnology to diagnose, characterize and manage disease at the molecular scale. As these strategies move closer to routine clinical use, a proper understanding of different imaging modalities, relevant biological systems and physical properties governing nanoscale interactions is necessary to rationally engineer next-generation bionanomaterials. In this Review, we analyse the background physics of several clinically relevant imaging modalities and their associated sensitivity and specificity, provide an overview of the materials currently used for in vivo nanodiagnostics, and assess the progress made towards clinical translation. This work provides a framework for understanding both the impressive progress made thus far in the nanodiagnostics field as well as presenting challenges that must be overcome to obtain widespread clinical adoption.

Chemical Interface Damping Depends on Electrons Reaching the Surface

Metallic nanoparticles show extraordinary strong light absorption near their plasmon resonance, orders of magnitude larger compared to nonmetallic nanoparticles. This "antenna" effect has recently been exploited to transfer electrons into empty states of an attached material, for example to create electric currents in photovoltaic devices or to induce chemical reactions. It is generally assumed that plasmons decay into hot electrons, which then transfer to the attached material. Ultrafast electron-electron scattering reduces the lifetime of hot electrons drastically in metals and therefore strongly limits the efficiency of plasmon induced hot electron transfer. However, recent work has revived the concept of plasmons decaying directly into an interfacial charge transfer state, thus avoiding the intermediate creation of hot electrons. This direct decay mechanism has mostly been neglected, and has been termed chemical interface damping (CID). CID manifests itself as an additional damping contribution to the homogeneous plasmon line width. In this study, we investigate the size dependence of CID by following the plasmon line width of gold nanorods during the adsorption process of thiols on the gold surface with single particle spectroscopy. We show that CID scales inversely with the effective path length of electrons, i.e., the average distance of electrons to the surface. Moreover, we compare the contribution of CID to other competing plasmon decay channels and predict that CID becomes the dominating plasmon energy decay mechanism for very small gold nanorods.

Understanding the Seed-Mediated Growth of Gold Nanorods through a Fractional Factorial Design of Experiments

Since the development of simple, aqueous protocols for the synthesis of anisotropic metal nanoparticles, research into many promising, valuable applications of gold nanorods has grown considerably, but a number of challenges remain, including gold-particle yield, robustness to minor impurities, and precise control of gold nanorod surface chemistry. Herein we present the results of a composite fractional factorial series of experiments designed to screen seven additional potential avenues of control and to understand the seed-mediated silver-assisted synthesis of gold nanorods. These synthesis variables are the amount of sodium borohydride used and the rate of stirring when producing seed nanoparticles, the age of and the amount of seeds added, the reaction temperature, the amounts of silver nitrate and ascorbic acid added, and the age of the reduced growth solution before seed nanoparticles are added to initiate rod formation. This statistical experimental design and analysis method, besides determining which experimental variables are important and which are not when synthesizing gold nanorods (and quantifying their effects), gives further insight into the mechanism of growth by measuring the degree to which variables interact with each other by mapping out their mechanistic connections. This work demonstrates that when forming gold nanorods by the reduction of auric ions by ascorbic acid onto seed nanoparticles, ascorbic acid determines how much gold is reduced, and the amount of seeds determine how it is divided, yet both influence the intrinsic growth rates, in both width and length, of the forming nanorods. Furthermore, this work shows that the reduction of gold proceeds via direct reduction on the surface of seeds and not through a disproportionation reaction. Further control over the length of gold nanorods can be achieved by tuning the amount of silver nitrate or the reaction temperature. This work shows that silver does not directly influence rod length or width, and a new primary role for silver is proposed as a catalyst promoting the reduction of gold on the ends of forming nanorods. Furthermore, this silver catalyst is removed from the reaction by adsorption onto the surface of the growing nanorod. This work also demonstrates the importance of freshly prepared silver nitrate and ascorbic acid solutions, free from even a few hours of photodegradation, in preparing gold nanorods with high shape purity and gold yield.

Shape Controlled Plasmonic Sn Doped CdO Colloidal Nanocrystals: A Synthetic Route to Maximize the Figure of Merit of Transparent Conducting Oxide

The synthesis of different anisotropic shaped (eight different shapes) Sn⁴⁺ doped CdO (Sn:CdO) colloidal nanocrystals (NCs) by precise tuning of precursor reactivity and proper choice of capping agent is reported. In all these systems, formation of Sn:CdO quantum dots (QDs) of 2-3 nm is identified at very early stage of reaction. The colloidally stable QDs act as a continuous source for the formation of primary nanoparticles that can be transformed selectively into specific type of nanoparticle morphology. The specific facet stabilization of fcc (face centered cubic)CdO is predicted by particular choice of ligand. Fine tuning of plasmonic absorbance band can be achieved by variation of Sn⁴⁺ doping concentration. Different anisotropic Sn:CdO NCs exhibit interesting shape dependent plasmonic absorbance features in NIR region. High quality crack free uniform dense thin film has been deposited on glass substrate to make high quality transparent conducting oxide (TCO) coatings. figure of merit of TCO can be maximized as high as 0.523 Ω^-1 with conductivity of 43 600 S cm^-1 and visible transmittance of ≈85% which is much higher than commercially available tin doped indium oxide and other transparent electrodes.

Seedless Synthesis of Monodispersed Gold Nanorods with Remarkably High Yield: Synergistic Effect of Template Modification and Growth Kinetics Regulation

Gold nanorods (AuNRs) are versatile materials due to their broadly tunable optical properties associated with their anisotropic feature. Conventional seed-mediated synthesis is, however, not only limited by the operational complexity and over-sensitivity towards subtle changes of experimental conditions but also suffers from low yield (≈15 %). A facile seedless method is reported to overcome these challenges. Monodispersed AuNRs with high yield (≈100 %) and highly adjustable longitudinal surface plasmon resonance (LSPR) are reproducibly synthesized. The parameters that influence the AuNRs growth were thoroughly investigated in terms of growth kinetics and soft-template regulation, offering a better understanding of the template-based mechanism. The facile synthesis, broad tunability of LSRP, high reproducibility, high yield, and ease of scale-up make this method promising for the future mass production of monodispersed AuNRs for applications in catalysis, sensing, and biomedicine.

Gold nanorod embedded large-pore mesoporous organosilica nanospheres for gene and photothermal cooperative therapy of triple negative breast cancer

To date, clinicians still lack an effective strategy to treat triple negative breast cancer (TNBC). In this work, we design for the first time a gold nanorod embedded large-pore mesoporous organosilica (GNR@LPMO) nanoplatform for gene and photothermal cooperative therapy of TNBC. The synthesized GNR@LPMOs possess a uniform size (175 nm), high surface area (631 m2 g-1), large pore size, excellent photothermal efficiency, and good biocompatibility. Thanks to the large-pore mesoporous organosilica layer, the GNR@LPMO nanoplatforms display much higher loading capacity of siRNA compared with traditional liposome and bare gold nanorods. Thus, functional siRNA can be efficiently delivered into TNBC cells by GNR@LPMOs, causing much higher cell apoptosis through knocking down the PLK1 proteins. By combining the effective gene delivery and photothermal abilities, the GNR@LPMO nanoplatforms are further used for gene and photothermal cooperative therapy of TNBC, which induce a 15 fold higher mice tumor inhibition rate than sole therapy modality, indicating the potential clinical use of this novel nanoplatform in treating TNBC.

Phage display-derived oligopeptide-functionalized probes for in vivo specific photoacoustic imaging of osteosarcoma

Specific detection of various tumor types remains crucial for designing effective treatment strategies. We demonstrate photoacoustic imaging (PAI) using high-affinity and high-specificity peptide-based probes for accurate and specific diagnosis of osteosarcoma. Herein, two new tumor-specific oligopeptides, termed PT6 and PT7, were identified using phage display-based screening on an osteosarcoma cell line (UMR-106). The identified oligopeptides were able to detect clinical osteosarcoma samples on tissue microarrays. Oligopeptide-conjugated PEGylated gold nanorods (PGNR) were designed to specifically target UMR-106 cells. More importantly, PAI revealed that both PGNR-PT6 and PGNR-PT7 could bind selectively to subcutaneous UMR-106 xenografts after systemic administration and enhance the contrast of osteosarcoma images by 170% and 230%, respectively, compared to tumor-bearing mice injected with PGNRs conjugated to scrambled oligopeptides. PAI employing PGNRs conjugated to specifically designed nanoprobes may provide a new method for tumor type-specific diagnosis of osteosarcoma.

Luminescent CaTiO3:Yb,Er nanofibers co-conjugated with Rose Bengal and gold nanorods for potential synergistic photodynamic/photothermal therapy

CaTiO₃:Yb,Er nanofibers, co-conjugated with Rose Bengal and gold nanorods, enable a synergistic photodynamic/photothermal phenomenon for superior cancer cell killing effect.

Spiky TiO2/Au nanorod plasmonic photocatalysts with enhanced visible-light photocatalytic activity

Spiky TiO₂/AuNR plasmonic photocatalysts show improved visible-light photocatalytic activity by simultaneously enhancing light harvesting, charge utilization efficiency, and substrate accessibility.

End-to-end assembly and disassembly of gold nanorods based on photo-responsive host–guest interaction

The end-to-end assembly and disassembly of gold nanorods were realized via HS-β-CD recognition and controllable by both UV light irradiation and guest competition.

Symmetry breaking during nanocrystal growth

This article highlights the mechanisms that guide the growth of nanocrystals to asymmetric shapes based on rationally designed wet-chemical syntheses.

Size-tunable uniform gold octahedra: fast synthesis, characterization, and plasmonic properties

Well-defined octahedral Au nanocrystals were facilely and precisely prepared in high yield by modified polyol process.

Colloidal Synthesis and Applications of Plasmonic Metal Nanoparticles

Plasmonic metal nanoparticles attract intense research attention because of their fascinating surface plasmon resonance properties and their potential applications in diverse fields. Here, some of the recent research efforts on the synthesis and applications of plasmonic metal nanoparticles are highlighted. Starting from the colloidal synthesis of metal nanoparticles, various shaped silver and gold nanostructures are discussed. The applications of plasmonic nanoparticles in photocatalysis, surface-enhanced Raman spectroscopy (SERS), and devices are used as excellent examples showcasing the advantages of these nanoparticles. The report closes with a brief summary and discussion on the challenges and future direction in this research field.

A significant enhancement of color transition from an on-off type achromatic colorimetric nanosensor for highly sensitive multi-analyte detection with the naked eye

Here, we report the development of an achromatic nanoparticle-based colorimetric sensor (achromatic nanosensor) with an on-off type color change that significantly enhances the color transition and increases the sensitivity of the sensor for naked-eye inspection. The achromatic nanosensor was prepared via a modified CMYK (CRYK) subtractive color model by combining DNA-functionalized gold nanoparticles (AuNPs-DNA), silver nanoparticles (AgNPs-DNA), and gold nanorods (AuNRs-DNA). The initially black-colored achromatic nanosensor not only allowed multiplexed detection by generating target-specific diverse color changes, but also improved the recognition of color changes by the naked eye. Thus, this on-off type color change enabled analysis near the limit of detection (LOD) with the naked eye. In addition, we developed a new image processing method adapted for this achromatic sensor. By quantifying the saturation value of the color images of the achromatic sensor, we could significantly amplify the color signal of the samples, which is difficult to achieve with general colorimetric sensors. The practical application of this achromatic nanosensor for biomarker detection was demonstrated with thrombin and platelet-derived growth factor (PDGF) in human blood plasma. These results provide a new sensing platform that is applicable to most NP-based colorimetric sensing systems for a wide range of applications, including biomolecular diagnosis, chemical pollutant sensing, environmental monitoring, etc.