Near-perfect fidelity polarization-encoded multilayer optical data storage based on aligned gold nanorods

Encoding information in light polarization is of great importance in facilitating optical data storage(ODS)for information security and data storage capacity escalation.However,despite recent advances in nanophotonic techniques vastly en-hancing the feasibility of applying polarization channels,the data fidelity in reconstructed bits has been constrained by severe crosstalks occurring between varied polarization angles during data recording and reading process,which gravely hindered the utilization of this technique in practice.In this paper,we demonstrate an ultra-low crosstalk polarization-en-coding multilayer ODS technique for high-fidelity data recording and retrieving by utilizing a nanofibre-based nanocom-posite film involving highly aligned gold nanorods(GNRs).With parallelizing the gold nanorods in the recording medium,the information carrier configuration minimizes miswriting and misreading possibilities for information input and output,respectively,compared with its randomly self-assembled counterparts.The enhanced data accuracy has significantly im-proved the bit recall fidelity that is quantified by a correlation coefficient higher than 0.99.It is anticipated that the demon-strated technique can facilitate the development of multiplexing ODS for a greener future.

Detection of Adhesion Molecules on Inflamed Macrophages at Early-Stage Using SERS Probe Gold Nanorods

In recent years, it has been shown that inflammatory biomarkers can be used as an effective signal for disease diagnoses. The early detection of these signals provides useful information that could prevent the occurrence of severe diseases. Here, we employed surface-enhanced Raman scattering(SERS) probe gold nanorods(GNRs) as a tool for the early detection of inflammatory molecules in inflamed cells. A murine macrophage cell line(Raw264.7) stimulated with lipopolysaccharide(LPS) was used as a model in this study. The prepared SERS probe GNRs containing 4-mercaptobenzoic acid as a Raman reporter to generate SERS signals were used for detection of intracellular adhesion molecule-1(ICAM-1) in macrophages after treatment with LPS for varying lengths of time. Our results show that SERS probe GNRs could detect significant differences in the expression of ICAM-1 molecules in LPS-treated macrophages compared to those in untreated macrophages after only 1 h of LPS treatment. In contrast, when using fluorescent labeling or enzyme-linked immunosorbent assays(ELISA) to detect ICAM-1, significant differences between inflamed and un-inflamed macrophages were not seen until the cells had been treated with LPS for 5 h. These results indicate that our SERS probe GNRs provide a higher sensitivity for detecting biomarker molecules in inflamed macrophages than the conventional fluorescence and ELISA techniques, and could therefore be useful as a potential diagnostic tool for managing disease risk.

Amperometric glucose biosensor based on gold nanorods and chitosan comodified Au electrode

Au nanorods were prepared by a seeding growth approach and used in fabricating the nanorod-enhancing glucose biosensor. The high affinity of chitosan for Au nanorods associated with its amino groups resulted in the formation of a layer of Au nanorods on the surface of Au electrode. It served as an intermediator to retain high efficient and stable immobilization of the enzyme. The performance of biosensors was investigated by cyclic voltammetry （CV）, in the presence of artificial redox mediator, ferrocenecarboxaldehyde. The biosensor had a fast response to glucose, and the response time was less than 10 s. The results indicated that the gold nanorods could enhance the current response to glucose. The detection limits of glucose can reach 10 mM, and the Michaelis-Menten constant Km^app is 13.62 mM.

Functionalized Gold Nanorods for Tumor Imaging and Targeted Therapy

Gold nanorods,as an emerging noble metal nanomaterial with unique properties,have become the new exciting focus of theoretical and experimental studies in the past few years.The structure and function of gold nanorods,especially their biocompatibility, optical property,and photothermal effects,have been attracting more and more attention.Gold nanorods exhibit great potential in applications such as tumor molecular imaging and photothermal therapy.In this article,we review some of the main advances made over the past few years in the application of gold nanorods in surface functionalization,molecular imaging,and photothermal therapy. We also explore other prospective applications and discuss the corresponding concepts,issues,approaches,and challenges,with the aim of stimulating broader interest in gold nanorod-based nanotechnology and improving its practical application.

Surface-enhanced Raman scattering properties of highly ordered self-assemblies of gold nanorods with different aspect ratios

Gold nanorods with aspect ratios of from 1 （particles） to 31.6 were synthesized by the seed-mediated method and packed in a highly ordered structure on a large scale on silicon substrates through capillary force induced self-assembly behaviour during solvent evaporation. The gold nanorod surface exhibits a strong enhancing effect on Raman scattering spectroscopy. The enhancement of Raman scattering for two model molecules （2-naphthalenethiol and rhodamine 6C） is about 5-6 orders of magnitude. By changing the aspect ratio of the Au nanorods, we found that the enhancement factors decreased with the increase of aspect ratios. The observed Raman scattering enhancement is strong and should be ascribed to the surface plasmon coupling between closely packed nanorods, which may result in huge local electromagnetic field enhancements in those confined junctions.

Gold Nanorods: Near-Infrared Plasmonic Photothermal Conversion and Surface Coating

In this paper, AuNRs colloids with SPRL located at ~810 nm and ~1100 nm were synthesized using an improved seed method. Based on the NIR lasers available, photothermal conversion of AuNRs were systematically studied compared with that of water. Under low power irradiation, the highest temperature is obtained when the SPRL wavelength of AuNRs is equal to the laser wavelength, and temperature of colloid increases from ~20°C to ~65°C. With increasing laser power (such as 6 W), the AuNRs colloid boils within a few minutes, and nanorods undergo a shape deformation from rod to spherical particle and even fusion, and the SPRL disappears. For further investigation, the obtained AuNRs were coated with SiO2 shell to form a core-shell nanostructure (Au@SiO2). The surface coating can be used not only in keeping the stability of AuNRs for further treatment, but also in increasing plasmonic property and biocompatibility. This work will be useful for designing plasmonic photothermal properties and further applications in nanomedicine.

Preparation of Gold Nanorods of High Quality and High Aspect Ratio

We report the synthesis of gold nanorods （NRs） by seed-mediated growth method. A small amount of different shapes such as triangles, hexagons and a large amount of rods are obtained by varying the proportion of seed to metal salt, adding NaOH to growth solution as well as using the seed solution of CTAB-capped agent. The gold nanorod （NR） formation yield is improved. Meanwhile, the growth mechanism of high yield gold NRs is discussed. The high quality single size NRs can be separated from polydisperse samples using surfactant-assisted nanorod self-assembly. The gold NRs synthesized were characterized by transmission electron microscopy （TEM） and UV-vis spectroscopy.

Gold nanorods for gambogicacid intracellular delivery

OBJECTIVE To improve the anticancer drug gambogic acid’s effect by using titanium dioxide coated gold nanorods(GNR/Ti O2)as a drug carrier.METHODS Biocompatibility and cellular uptake of GNR/Ti O2was studied in human glioblastoma U-87 MG cells.Cel viability was evaluated by ATP assay and calcein AM staining.Lyso SensorTMGreen DND-189 and Hoechst 33342 were used to analyze the intracellular location of GNR/Ti O2.The in vitro anticancer effect of gambogic acid loaded nanoparticles was compared with free drug.RESULTS The results showed that GNR/Ti O2is biocompatible,andthey are localized at the intracellular acidic compartments of endosomes and lysosomes.The intracellular drug content delivered via GNR/Ti O2was 6 fold higher than the free form,thus dramatically enhancing the anticancer effect of gambogic acid.Furthermore,mild photothermal therapy also showed synergistic effect with the drug.CONCLUSION Our study suggested that GNR/Ti O2is a promising anticancer drug carrier。

Efficient plasmon-enhanced perovskite solar cells by molecularly isolated gold nanorods

Perovskite solar cells(PSCs)are becoming a promising candidate for next-generation photovoltaic cells due to their attractive power conversion efficiency(PCE).Plasmonic enhancement is regarded as an optical tuning approach for further improving the PCE of single-junction PSCs toward Shockley-Queisser limit.Herein,we introduce molecularly isolated gold nanorods(Au NRs),bearing relatively stronger scattering ability and localized surface plasmonic resonance(LSPR)effect,in the rear side of perovskites in PSCs,for promoting light harvesting and for electrical enhancement.Owing to the larger refractive index and better matched energy level alignment,the 4-mercaptobenzoic acid molecules coated on Au NRs prove to play important dual roles:isolating the metallic Au NRs from contacting with perovskite,and facilitating more efficient charge separation and transport across the interface under the synergetic LSPR effect of Au NRs.Our work highlights the capability of the plasmonic approach by nanorods and by molecular isolation,extending nanoparticle-based plasmonic approaches,toward highly efficient plasmon-enhanced PSCs.

High Thermal Stability Gold Nanorods Included Alumina Film Prepared by a Dip-lifting Method

Here,we designed and prepared a new nano-assembly structure of gold nanorods dispersion medium to improve the data storage life.The surface of gold nanorods was wrapped with a layer of silica shell to enhance the nanorod thermal stability,and then injected into the porous alumina to form a nano-assembly structured film.The experimental results show that gold nanorods are uniformly dispersed in the alumina film,and the optical properties of gold nanorods will not change after heat treatment below 200℃.It is expected that this film can be used for five-dimensional data storage and greatly improve the thermal stability of stored data.

Hyaluronic Acid-RGD Peptide Conjugated Mesoporous Silica-coated Gold Nanorods for Cancer Dual-targeted Chemo-photothermal Therapy

A multifunctional drug delivery system（GNRs@mSiO_2-HA-RGD） was developed by conjugating targeting ligand hyaluronic acid（HA） and RGD with mesoporous silica-coated gold nanorods（GNRs@mSiO_2） for dual-targeted chemo-photothermal therapy. The physiochemical properties of the prepared nanoparticles were characterized by FTIR, UV-vis spectra, and ~1H NMR. Doxorubicin hydrochloride（DOX）, an anticancer drug, was used as the model drug to investigate the drug loading, in vitro drug release profiles and cytotoxicity. The experimental results show that DOX-GNRs@mSiO_2-HA-RGD is synthesized with a mean diameter of 116 nm and a sufficient load capacity of about 19.8%. It also has p H-enzyme sensitive and NIRtriggered drug release manner. Cellular uptake indicates that DOX-GNRs@mSiO_2-HA-RGD exhibits a higher cellular uptake via CD44 receptor and integrin receptor mediated endocytosis compared with the GNRs@mSiO_2 modified with one receptor or no receptor. In comparison with chemotherapy or photothermal therapy alone, DOX-GNRs@mSiO_2-HA-RGD displayes the synergistic effects and achieves a higher therapeutic efficacy. It can be expected that DOX-GNRs@mSiO_2-HA-RGD is a potential dual-targeted chemo-photothermal therapeutic platform for effective cancer treatment.

Effects of Gold Nanorods on Nonlinear Properties of Graphene Films Using Z-Scan Technique

Two dimensional nanomaterials, specifically graphene, can play a significant role in various photonic and electronic devices. This is especially true in handling the enormous heat in high density electronics and in nonlinear optics when using high power lasers. To model these systems it is important to know the thermal-optical properties of graphene. In this paper, we report on the thermal and optical linear and nonlinear properties of graphene materials using Z-scan system. In particular, we explore the thermo-optical properties of graphene, with and without gold nanorods （AuNRs）. The obtained results illustrate that the addition of gold nanorods causes a significant change in thermal nonlinear refractive index coefficients of graphene, due to the plasmonic enhancements.

Gold Nanorods-mediated Photothermal Therapy Guided by Vascular Interventional Radiation to Inhibit Cancer Metastasis

The purpose of this study was to investigate the inhibitory effect of gold nanorods-mediated photothermal therapy on liver metastasis of colorectal cancer under the guidance of vascular interventional radiology.A total of 80 patients admitted to our hospital from February 2018 to February 2020 were selected and randomly divided into study group and control group with 40 cases each,among which the control group received 125I seed implantation combined with chemotherapy.On this basis,the study group were added the gold nanorods(AuNRs)to the photothermal therapy additionally.The clinical efficacy,postoperative complications and postoperative survival rates of the two groups were compared.The results showed that the total clinical effective rate was 82.5%in the study group,which was significantly better than 67.5%in the control group,and the difference was statistically significant(P<0.05).In addition,the incidence of leukocytosis,nausea,vomiting and delayed diarrhea in the study group was significantly lower than that in the control group,with statistically significant differences(P<0.05).There were no statistically significant differences in the proportion of elevated body temperature,liver dysfunction,or moderate liver pain between the two groups(P>0.05).Therefore,under the guidance of vascular interventional radiology,Au NRs are safe and effective materials for the treatment of liver metastasis of colorectal cancer,which can reduce complications and improve postoperative survival rates.

Thermal Nonlinearity of Functionalized Graphene Enhanced by Gold Nanorods

The nonlinearity of functionalized and nonfunctionlaized graphene as well as gold nanorods were investigated using the Z-scan system with an Ar＋ laser beam tuned at a wavelength of 514 nm in a CW （continuous wave） regime that was in resonance with AuNRs （gold nanorods）. Z-scan experimental study indicated that functionalized graphene had a negative nonlinear refraction with self-defocusing performance. The result concluded that gold nanorods （average length was 36 ± 3 nm, and the average diameter was 12 ± 2 nm） enhance the thermal nonlinear properties of graphene oxide materials. Gold nanorods were proved to enhance the nonlinear absorption by 50%, and there was a large enhancement on the thermal nonlinear refraction and the thermo-optical coefficient （dn/dT）. It was observed that the AuFG （functionalized graphene film with gold nanorods） presented a large thermal nonlinear refraction. The value of the nonlinear refraction （nl＇） of FG and AuFG samples was shifted from -0.533 x 10.7 cm2/W to -2.92 x 10-7 cm2/W. There was a large enhancement in thermal refraction value that was about five factors larger than the nonlinear refraction of the host material （FG） and much larger （4 orders of magnitude） than that for AuNRs.

Seedless Synthesis of Gold Nanorods with 5–10 nm in Diameters:a Comprehensive Study

Small gold nanorods(AuNRs),namely AuNRs with less than 10 nm in diameter,possess a high absorption-to-scattering ratio,a large surface area-to-volume ratio,as well as high cellular uptake behaviors.In this study,we systematically investigate seedless synthesis of AuNRs with diameters ranging from 5 nm to 10 nm.It has been found that several experimental conditions,including the chain length of the used cationic surfactants,and the concentrations of ascorbic acid,NaBH4,and AgNO_(3)can profoundly affect the obtained products.Under optimal conditions,the production yields of the obtained several AuNRs with different diameters can exceed 90%and even reach almost 100%.The conversion of gold precursors to AuNRs was estimated to be 70%–77%as measured by absorption spectroscopy and inductively coupled plasma mass spectrometry.

Ultrasensitive detection of micro RNA-21 in human serum based on the confinement effect enhanced chemical etching of gold nanorods

Natural enzymes,such as horseradish peroxidase(HRP),are a class of important biocatalysts with the high specificity,but their catalytic efficiency is usually unsatisfactory.Thus,the higher catalytic efficiency induced by the confinement effect is promising in optical sensing systems.In this work,a dark-field light scattering sensing platform was fabricated by the confinement effect of HRP from hybridization chain reaction(HCR)and then released to solution by the toehold-mediated strand displacement reaction(TSDR).Then,HRP catalyzed the 3,3,5,5-tetramethylbenzidine(TMB)to TMB^(2+)with the assistance of hydrogen peroxide,which etched the gold nanorods(Au NRs)with the weakened light scattering.The single-particle assay was established based on the decreased light scattering intensity of AuNRs under dark-field microscope.The proposed assay revealed excellent analytical performance within a linear range from 25 pmol/L to 600 pmol/L,and a low limit of detection of 3.12 pmol/L.Additionally,it also manifested satisfactory recovery of mi RNA-21 in human serum samples.The high sensitivity,excellent specificity,and universal applicability make this sensing platform promising for disease diagnosis.

Fluorescent Silicon Nanorods-Based Nanotheranostic Agents for Multimodal Imaging-Guided Photothermal Therapy

The utilization of diagnosis to guide/aid therapy procedures has shown great prospects in the era of personalized medicine along with the recognition of tumor heterogeneity and complexity.Herein,a kind of multifunctional silicon-based nanostructure,i.e.,gold nanoparticles-decorated fluorescent silicon nanorods(Au@SiNRs),is fabricated and exploited for tumor-targeted multimodal imaging-guided photothermal therapy.In particular,the prepared Au@SiNRs feature high photothermal conversion efficiency(~43.9%)and strong photothermal stability(photothermal performance stays constant after five-cycle NIR laser irradiation),making them high-performance agents for simultaneously photoacoustic and infrared thermal imaging.The Au@SiNRs are readily modified with targeting peptide ligands,enabling an enhanced tumor accumulation with a high value of^8.74%ID g?1.Taking advantages of these unique merits,the Au@SiNRs are superbly suitable for specifically ablating tumors in vivo without appreciable toxicity under the guidance of multimodal imaging.Typically,all the mice treated with the Au@SiNRs remain alive,and no distinct tumor recurrence is observed during 60-day investigation.

Effect of spatially nonlocal versus local optical response of a gold nanorod on modification of the spontaneous emission

The spontaneous emission rate of a two-level quantum emitter(QE)near a gold nanorod is numerically investigated.Three different optical response models for the free-electron gas are adopted,including the classical Drude local response approximation,the nonlocal hydrodynamic model,and the generalized nonlocal optical response model.Nonlocal optical response leads to a blueshift and a reduction in the enhancement of the spontaneous emission rate.Within all the three models,the resonance frequency is largely determined by the aspect ratio(the ratio of the nanorod length to the radius)and increases sharply with decreasing aspect ratio.For nanorod with a fixed length,it is found that the larger the radius is,the higher the resonance frequency is,and the smaller the enhancement is.However,if the length of the nanorod increases,the peak frequency falls sharply,while the spontaneous emission enhancement grows rapidly.For nanorod with a fixed aspect ratio,the peak frequency decreases slowly with increasing nanorod size.Larger nanorod shows smaller nonlocal effect.At a certain frequency,there is an optimal size to maximize the enhancement of the spontaneous emission rate.Higher order modes are more affected by the nonlocal smearing of the induced charges,leading to larger blueshift and greater reduction in the enhancement.These results should be significant for investigating the spontaneous emission rate of a QE around a gold nanorod.

Angle-Resolved Plasmonic Properties of Single Gold Nanorod Dimers

Through wet-chemical assembly methods, gold nanorods were placed close to each other and formed a dimer with a gap distance *1 nm, and hence degenerated plasmonic dipole modes of individual nanorods coupled together to produce hybridized bonding and antibonding resonance modes. Previous studies using a condenser for illumination result in averaged signals over all excitation angles. By exciting an individual dimer obliquely at different angles, we demonstrate that these two new resonance modes are highly tunable and sensitive to the angle between the excitation polarization and the dimer orientation, which follows cos2 u dependence. Moreover, for dimer structures with various structure angles, the resonance wavelengths as well as the refractive index sensitivities were found independent of the structure angle. Calculated angle-resolved plasmonic properties are in good agreement with the measurements. The assembled nanostructures investigated here are important for fundamental researches as well as potential applications when they are used as building blocks in plasmon-based optical and optoelectronic devices.