Star-shaped Gold Nanoparticles Research Articles

Development and characterization of a lateral flow immunochromatographic assay test strip for rapid detection of rubella virus antigen

Rubella is still considered a dangerous infectious disease, especially for pregnant women. The symptoms of rubella can be similar to those of other illnesses. Therefore, an early and accurate diagnosis of the rubella virus will help doctors make a reasonable treatment plan. This study presents the development and characterization of a novel lateral flow immunochromatographic assay test strip for rapid recognition of rubella virus antigen. Rabbit polyclonal antibodies against the rubella virus were purified with a purity of 95%. Optimal conditions for the production of the main components of a test strip were determined. Anti-rubella virus polyclonal antibodies were physically adsorbed onto the star-shaped gold nanoparticles at the optimal concentration of 1.0 μg/ml at 25°C for 30 min. The amounts of antibody per conjugate pad and immobilized on the test line were 0.2 μg/pad and 4.5 μg/cm, respectively. The properties of the test strip were characterized by testing mock clinical specimens. Reproducibility and repeatability were achieved at 100%. The limit of detection of the test strip was determined to be as low as 5 × 105 virus particles/mL. The test strip did not cross-react with six different potential interfering pathogens. The sensitivity and specificity of the test strip were determined by testing with 400 mock clinical samples and reached 99.5% and 98.5%, respectively. The Kappa statistics (k coefficient = 0.98) showed very good agreement between the generated test strip and real-time PCR results. According to the findings, the test strip can be used as an additional rapid test tool for the detection of the rubella virus.

Gold nanostars loaded fabrics as flexible, low-cost SERS substrates and swab-based detection of thiram on fruits and vegetables

Currently, flexible surface-enhanced Raman spectroscopy (SERS) substrates have gained tremendous interest because they enable sample collection from uneven surfaces in real sensing applications. Herein, two different flexible textiles (cotton and synthetic fabrics) loaded with star-shaped gold (Au) nanoparticles (NPs) were utilized for detailed studies and are demonstrated as SERS substrates. Both fabrics were soaked in Au NPs synthesized via a simple wet chemical method. The colloidal star-shaped Au NPs were characterized by UV-visible absorption and transmission electron microscopy techniques. The C- and S-fabrics loaded with Au NPs were characterized by FESEM, x-ray diffraction, and x-ray photoelectron spectroscopic techniques. Subsequently, the SERS efficiency of C- and S-fabrics was examined with thiram, methylene Blue (MB), and Nile Blue (NB) molecules. Furthermore, pesticide (thiram) residues on the surfaces of a banana, an apple, and a spinach leaf were investigated by a simple swabbing method. The utility of these substrates is demonstrated by performing the SERS measurements using a portable Raman spectrometer, which is expedient for real-time applications.

Optical properties of planar plasmon active surfaces modified with gold nanostars

The article discusses the experimental and theoretical results of studying the optical properties for planar quartz surfaces modified with gold nanostars using Surface-Enhanced Raman Spectroscopy (SERS). Surfaces functionalized with nanoparticles, prototypes of optical sensors, have been obtained. It is shown that the obtained experimental Raman signal enhancement from the dye rhodamine 6G (R6G) can be at least order 104. The paper presents the results of calculation, synthesis and study of the optical and morphological properties of such structures. A complex method for creating and evaluating the optical properties of planar nanostructures and evaluating their optical properties is proposed. The method includes the approaches based on mathematical modeling using finite differences in the time domain (FDTD - Finite-Difference Time-Domain) evaluating electromagnetic field strengths near the surfaces of star-shaped gold nanoparticles in colloidal solutions and on a silicon surface. During the simulation, we studied such parameters as the particle size, the wavelength of the exciting radiation, and the dependence of the effective amplification of the electromagnetic field on the morphological parameters of the star. The theoretical approach to the calculation of such structures is shown to be promising for the subsequent chemical synthesis described in the article and the study of optical properties. In this paper, a theoretical calculation of the parameters of the electric field and optical properties is carried out near star-shaped nanoparticles of varying sizes. These parameters were calculated by the finite difference method in the time domain. The task included finding the optimal sizes of nanoparticles as well as varying the thickness of the surface layers in order to obtain the maximum scattering values and further use of similar structures in SERS experiments. Also, within the framework of this work, syntheses of star-shaped nanoparticles was carried out, their optical and morphological properties were studied, quartz surfaces were functionalized with nanoparticles, and sensor prototypes were created in order to further assess the Raman signal amplification. Based on the results of mathematical modeling, the optimal sizes for the synthesis of star-shaped NPs were determined. Synthesis of NPs was carried out by a chemical method using seeds. To carry out the experimental part, SERS spectra were obtained using Centaur U spectrometer (OOO NanoScanTechnology, Russia). The spectrometer was equipped with three different laser sources: 632.8 nm He-Ne laser (17 mW), 532 nm and 473 nm DPSS lasers (45 mW). During the experiment, a He-Ne laser with λ = 632 nm and DPSS laser with λ = 532 nm were used to match the excitation of the plasmon maximum for the nanostars. The optical scheme of the spectrometer included an Olympus BX41 microscope (Olympus, Japan) with a 100× objective (NA 0.9) for positioning the beam and collecting scattered photons. The monochromator of the spectrometer had a focal length of 800 mm. A holographic diffraction grating of 300 gr/mm, and was equipped with a 1024×256 pixel thermoelectric cooled CCD detector (Andor Tech., UK). As a result of the paper, surfaces functionalized by nanoparticles were obtained prototypes of optical sensors. It is shown that the experimental gain of the Raman signal can be no less than 104 times. The presented data will serve as the basis for obtaining the required sizes of nanostars in the methods of the controlled chemical synthesis of colloidal nanoparticles. The results presented in the article can be applied to the development of biocompatible and highly sensitive optical sensors based on the effect of Raman scattering of light.

Оптические метки на основе золотых нанозвёзд для ГКР-картирования тканей с использованием красных медицинских лазеров

Star-shaped gold nanoparticles modified with cyanine 5.5 derivatives were studied as optical tags for bioimaging by surface-enhanced Raman scattering (SERS). Obtained tags showed a plasmon resonance band at 640 nm in the absorption spectra which ensures them a maximum efficiency when excited by red lasers. SERS measurements were carried out for the modified particles in the solution phase and after incubation with the PANC-1 cell line. The SERS spectra of the solutions revealed a characteristic signal of cyanine 5.5 amino derivative in the range of 100–1000 cm–1, where there is no high fluorescent background. In cell samples, the SERS spectrum of the dye was recorded from the cytoplasm and was not detected outside the cells. In order to confirm the intracellular localization of the tags, the SERS spectra were also scanned in height. The test on cytotoxicity showed that the studied tags are not toxic in the concentration range from 0.05 to 1 mg/l on atomic gold.

Gold nanostars for SERS mapping of tissues using red medical lasers

Star-shaped gold nanoparticles modified with cyanine 5.5 derivatives were studied as optical tags for bioimaging by surface-enhanced Raman scattering (SERS). Obtained tags showed a plasmon resonance band at 640 nm in the absorption spectra which ensures them a maximum efficiency when excited by red lasers. SERS measurements were carried out for the modified particles in the solution phase and after incubation with the PANC-1 cell line. The SERS spectra of the solutions revealed a characteristic signal of cyanine 5.5 amino derivative in the range of 100-1000 cm-1, where there is no high fluorescent background. In cell samples, the SERS spectrum of the dye was recorded from the cytoplasm and was not detected outside the cells. In order to confirm the intracellular localization of the tags, the SERS spectra were also scanned in height. The test on cytotoxicity showed that the studied tags are not toxic in the concentration range from 0.05 to 1 mg/l on atomic gold. Keywords: surface-enhanced Raman scattering, gold nanostar, cyanine, optical tags, bioimaging

Gold Nanostars with Reduced Fouling Facilitate Small Molecule Detection in the Presence of Protein.

Gold nanoparticles have the potential to be used in biomedical applications from diagnostics to drug delivery. However, interactions of gold nanoparticles with different biomolecules in the cellular environment result in the formation of a “protein corona”—a layer of protein formed around a nanoparticle, which induces changes in the properties of nanoparticles. In this work we developed methods to reproducibly synthesize spheroidal and star-shaped gold nanoparticles, and carried out a physico-chemical characterization of synthesized anionic gold nanospheroids and gold nanostars through transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential (ZP), nanoparticles tracking analysis (NTA), ultraviolet-visible (UV–Vis) spectroscopy and estimates of surface-enhanced Raman spectroscopy (SERS) signal enhancement ability. We analyzed how they interact with proteins after pre-incubation with bovine serum albumin (BSA) via UV–Vis, DLS, ZP, NTA, SERS, cryogenic TEM (cryo-TEM) and circular dichroism (CD) spectroscopy. The tests demonstrated that the protein adsorption on the particles’ surfaces was different for spheroidal and star shaped particles. In our experiments, star shaped particles limited the protein corona formation at SERS “hot spots”. This benefits the small-molecule sensing of nanostars in biological media. This work adds more understanding about protein corona formation on gold nanoparticles of different shapes in biological media, and therefore guides design of particles for studies in vitro and in vivo.

Bactericidal Properties of Rod-, Peanut-, and Star-Shaped Gold Nanoparticles Coated with Ceragenin CSA-131 against Multidrug-Resistant Bacterial Strains.

Background: The ever-growing number of infections caused by multidrug-resistant (MDR) bacterial strains requires an increased effort to develop new antibiotics. Herein, we demonstrate that a new class of gold nanoparticles (Au NPs), defined by shape and conjugated with ceragenin CSA-131 (cationic steroid antimicrobial), display strong bactericidal activity against intractable superbugs. Methods: For the purpose of research, we developed nanosystems with rod- (AuR NPs@CSA-131), peanut-(AuP NPs@CSA-131) and star-shaped (AuS NPs@CSA-131) metal cores. Those nanosystems were evaluated against bacterial strains representing various groups of MDR (multidrug-resistant) Gram-positive (MRSA, MRSE, and MLSb) and Gram-negative (ESBL, AmpC, and CR) pathogens. Assessment of MICs (minimum inhibitory concentrations)/MBCs (minimum bactericidal concentrations) and killing assays were performed as a measure of their antibacterial activity. In addition to a comprehensive analysis of bacterial responses involving the generation of ROS (reactive oxygen species), plasma membrane permeabilization and depolarization, as well as the release of protein content, were performed to investigate the molecular mechanisms of action of the nanosystems. Finally, their hemocompatibility was assessed by a hemolysis assay. Results: All of the tested nanosystems exerted potent bactericidal activity in a manner resulting in the generation of ROS, followed by damage of the bacterial membranes and the leakage of intracellular content. Notably, the killing action occurred with all of the bacterial strains evaluated, including those known to be drug resistant, and at concentrations that did not impact the growth of host cells. Conclusions: Conjugation of CSA-131 with Au NPs by covalent bond between the COOH group from MHDA and NH3 from CSA-131 potentiates the antimicrobial activity of this ceragenin if compared to its action alone. Results validate the development of AuR NPs@CSA-131, AuP NPs@CSA-131, and AuS NPs@CSA-131 as potential novel nanoantibiotics that might effectively eradicate MDR bacteria.

One-Pot, Surfactant-Free Synthesis of Gold Nanostars and Evaluation of Their Antibacterial Effects against Propionibacterium acnes

Anisotropic gold nanoparticles, especially gold nanostars, are used in many fields of biomedical applications such as sensing, targeted drug delivery, and diagnostic and photothermal therapy. In this study, we introduced a novel application of gold nanostars as an antimicrobial agent. While spherical gold nanoparticles have an inappreciable effect, gold nanostars exhibit significant antibacterial activity. Besides, the seed-mediated method, a conventional technique for preparing gold nanostars, is rather complex and toxic to human and environment due to unsafe synthesized materials such as surfactants and reducers. In recent years, green chemistry for nanoparticle synthesis is attractive because of its advantages. Instead of the seed-mediated procedure, we present a facile and green procedure to synthesize gold nanostars using ascorbic acid as a reductant and chitosan as a directing-growth agent. The influences of reacting parameters were evaluated to determine the optimal conditions. Star-shaped gold nanoparticles were successfully synthesized with average size tunning from 137.0 ± 20.7 nm to 281.9 ± 25.8 nm of the core and 14.0 ± 4.4 nm to 54.2 ± 11.9 nm of branches. Antibacterial activity against Propionibacterium acnes of gold nanostars was also investigated. Propionibacterium acnes is one of the main reasons causing acne vulgaris. The antibacterial test was evaluated by the plate count and well diffusion method. The results showed a significant effect that gold nanostars could be the prospective agent for replacing antibiotics in acne treatment.

Surface-enhanced Raman scattering-based molecular encoding with gold nanostars for anticounterfeiting applications

Star-shaped gold nanoparticles with encoded molecular information can be used in security inks for anticounterfeiting applications.

Synthesis of gold nanostar using chitosan as reductive agent by the seedless reduction method

The gold nanostars (AuNS) were prepared through seedless reductive method by using the natural biodegradable polymer chitosan acting both as the stabilizing and shape-directing agent, ascorbic acid as a reducting agent. This reaction synthesis was carried out at room temperature and facile conditions. In an effort to control the size and shape of AuNS, many experimental parameters were investigated for the thorough understanding the role of chitosan in the formation of gold nanostar. In this novel method, the pH condition and appropriate stabilizer concentration were crucial factors to prepare the well-defined AuNS. The obtained AuNS were characterized by many physical-chemistry analysis method such as transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy, dynamic light scattering (DLS), and X-Ray diffraction (XRD). The AuNS have an average size of about 55 nm and narrow size distribution when characterized by TEM images. UV-Vis spectroscopy of the gold nanoparticles colloidal solution showed the characteristic peaks at 587-700 nm, corresponding to the surface plasmon resonance of star-shaped nanostructure. The specific interactions between the functional groups of chitosan chain and the as-prepared gold nanostars are analyzed by the FT-IR spectroscopy technique. These results provided insight into the role of biopolymer as both a protecting agent and structure-directing agent. This novel method can overcome previous limitations in controlled synthesis of star-shaped gold nanoparticles such as surfactant use and complex implementation. Besides, the gold nanostars stabilized by chitosan could be a potential material in many applications in the field of biomedical medicine.

Reproducible Ionization of Gold Nanospheres and Nanostars in Gelatin Sections

Abstract Gold nanospheres were dispersed in gelatin sections (10–100 µm thickness) and their laser desorption/ionization (LDI) efficiencies of gold ions (Au+, Au2+, Au3+) under pulsed-laser irradiation were examined. The mass signal intensities were linear to the surface densities ranging from 6 × 104 to 6 × 106 particles/mm2. When the thickness of the sections was thinner than or equal to 50 µm, the LDI efficiency of gold nanospheres was independent of the thickness. Thus, the mass intensity was dependent on the surface densities of gold nanospheres in the gelatin sections. It was also found that the LDI efficiencies were affected by the concentration of gelatin solutions. Based on the high reproducibility of mass signals obtained from gelatin sections, the LDI efficiencies of star-shaped gold nanoparticles (gold nanostars) were also evaluated. It was found that the nanostars showed higher LDI efficiencies than gold nanospheres, but the enhancement was not more than 25%.

Yolk–Shell Structured Au Nanostar@Metal–Organic Framework for Synergistic Chemo-photothermal Therapy in the Second Near-Infrared Window

Light-sensitive yolk-shell nanoparticles (YSNs) as remote-controlled and stimuli-responsive theranostic platforms provide an attractive method for synergistic cancer therapy. Herein, a kind of novel stimuli-responsive multifunctional YSNs has been successfully constructed by integrating star-shaped gold (Au star) nanoparticles as the second near-infrared (NIR-II) photothermal yolks and biodegradable crystalline zeolitic imidazolate framework-8 (ZIF-8) as the shells. In this platform, a chemotherapeutic drug (doxorubicin hydrochloride, DOX) was encapsulated into the cavity, which can show the behavior of controlled release due to the degradation process of ZIF-8 in the mildly acidic tumor microenvironment. Upon the 1064 nm (NIR-II biowindow) laser irradiation, gold nanostar@ZIF-8 (Au@MOF) nanoparticles exhibited outstanding synergistic anticancer effect based on their photothermal and promoted cargo release properties. Moreover, the strong NIR region absorbance endows the Au@MOF of NIR thermal imaging and photoacoustic (PA) imaging properties. This work contributes to design a stimuli-responsive "all-in-one" nanocarrier that realizes bimodal imaging diagnosis and chemo-photothermal synergistic therapy.

Star-shaped plasmonic nanostructures: New, simply synthetized materials for Raman analysis of surfaces.

In this contribution we show that star-shaped gold nanoparticles and star-shaped nanostructures containing a gold core (Au@SiO2, Au@Ag, and Au@Ag@SiO2) can be used as very efficient, easy to produce and reproducible electromagnetic nanoresonators for the Raman analysis of surfaces, especially for shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) measurements. The "one pot" procedure used in this work for synthesizing star-shaped gold nanoparticles (a reduction of chloroauric anions by hydrogen peroxide in an alkaline solution) is one of the simplest procedures for synthesizing highly anisotropic plasmonic nanostructures containing many sharp apexes and edges. There is no need to purify the obtained samples of gold nanostars - under these conditions, the formation of nanoparticles having other shapes and significantly different sizes is neglected. Moreover, there is no need to purify the nanoparticles obtained from any surfactant, whereas such purification is usually required when other anisotropic gold nanoparticles are synthetized. We found that the gold nanostars obtained are about one order of magnitude more efficient as nanoresonators for carrying out Raman analysis of a model surface than the equivalent standard spherical nanostructures. We also studied the effect of the silica layer on the stability of Au@Ag star-shaped nanoparticles in contact with yeast cells.

Abstract 4152: Synergistic gold nanostar-mediated photothermal and immunotherapy for cancer metastasis treatment

Abstract Cancer has become a severe thread to human health resulting in more than eight million deaths each year. Cancer metastasis is the main mechanism in more than 90 percent of cancer deaths. However, current therapeutic options including chemotherapy and radiation therapy have limited therapeutic effects to treat cancer metastasis. Therefore, there is an urgent need to develop novel methods for cancer treatment. Our group has developed a unique method to synthesize star-shaped gold nanoparticles, gold nanostars (GNS), without using toxic surfactant, which is very suitable for in vivo applications. The synthesized GNS has tip-enhanced plasmonics and tunable strong in the near-infrared “tissue optical window”, enabling it a superior photon-to-heat nanotransducer. The GNS nanoparticles accumulate preferably into tumor with enhanced permeability and retention (EPR) effect after intravenous administration. We have applied GNS for photothermal therapy with 808 nm laser to specifically ablate tumor. Here we report a new cancer treatment method by combing nanophotothermal therapy and anti-PD-L1 immunotherapy. Immunogenic cell death is often insufficient to trigger effective anti-cancer immunity due to the presence of immunosuppressive factors occurring in the tumor microenvironment such as hypoxia, impaired leukocyte trafficking and inhibitory immune checkpoint signaling. The GNS-mediated photothermal ablation can reduce hypoxia and improve leukocyte trafficking to the tumor. In addition, the administration of anti-PD-L1 antibody reverses another critical immunosuppression factor. Experiment results using a mouse bladder cancer model demonstrated that the combined photothermal and immunotherapy have synergistic effect and can not only eradicate primary tumors with laser treatment but also distant metastasis without laser treatment. Furthermore, delayed rechallenge in the cured mice didn't result in new tumor generation, indicating that our combined therapy induced memorized immune response against cancer. The combined GNS-mediated photothermal therapy and anti-PD-L1 immunotherapy has promise to improve therapeutic effect on not only primary tumor but also cancer metastasis. Citation Format: Yang Liu, Paolo Maccarini, Gregory M. Palmer, Brant A. Inman, Tuan Vo-Dinh. Synergistic gold nanostar-mediated photothermal and immunotherapy for cancer metastasis treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4152.

Interactions of Fluorescein Dye with Spherical and Star Shaped Gold Nanoparticles.

UV-vis absorption, FT-IR, steady state fluorescence and fluorescence lifetime measurements were made on Fluorescein dye (Fl dye) molecules in presence of gold nanoparticles of different morphologies: spherical gold nanoparticles (GNP) and star shaped gold nanoparticles (GNS). The experimental observations demonstrate that Fl dye molecules form dimers when adsorbed on nanosurface of spherical gold particles. On the other hand possibly due to lack of adsorption on the surface of GNS the dye molecules were unable to form dimers. The projected tips on the surface of GNS may possibly hinder the dyes to adsorb on the surface of this nanoparticle. From the spectral analysis and measurements of thermodynamic parameters it is inferred that two different types of ground state interactions occur between Fl-dye-GNP and Fl dye-GNS systems. Both the observed negative values of the thermodynamic parameters ΔH and ΔS in the case of the former system predict the possibility of occurrences of hydrogen bonding interactions between two neighboring Fl dye molecules when adsorbed on the nanosurface of GNP. On the other hand in Fl dye-GNS system electrostatic interactions appear to occur, as evidenced from negative ΔH and positive value of ΔS, between the positive charges residing on the tips of the nanoparticles and anionic form of Fl dye. It has been concluded that as the adsorption of organic dyes on solid surfaces is prerequisite for the degradation of dye pollutants, the present experimental observations demonstrate that GNP could be used as a better candidate than GNS in degradation mechanism of the xanthenes dyes.

Near-field marking of gold nanostars by ultrashort pulsed laser irradiation: experiment and simulations

Quantitative measurements of the electric near-field distribution of star-shaped gold nanoparticles have been performed by femtosecond laser ablation. Measurements were carried out on and off the plasmon resonance. A detailed comparison with numerical simulations of the electric fields is presented. Semi-quantitative agreement is found, with slight systematic differences between experimentally observed and simulated near-field patterns close to strong electric-field gradients. The deviations are attributed to carrier transport preceding ablation.

Fluidic Manufacture of Star-Shaped Gold Nanoparticles.

Star-shaped gold nanoparticles (StarAuNPs) are extremely attractive nanomaterials, characterized by localized surface plasmon resonance which could be potentially employed in a large number of applications. However, the lack of a reliable and reproducible synthetic protocols for the production of StarAuNPs is the major limitation to their spreading. For the first time, here we present a robust protocol to manufacture reproducible StarAuNPs by exploiting a fluidic approach. Star-shaped AuNPs have been synthesized by means of a seed-less protocol, employing ascorbic acid as reducing agent at room temperature. Moreover, the versatility of the bench-top microfluidic protocol has been exploited to afford hydrophilic, hydrophobic and solid-supported engineered StarAuNPs, by avoiding intermediate NP purifications.

Plasmonic Nanostars as Efficient Broadband Scatterers for Random Lasing.

Huge spectral coverage of random lasing throughout the visible up to the infrared range is achieved with star-shaped gold nanoparticles (“nanostars”). As intrinsically broadband scattering centers, the nanostars are suspended in solutions of various laser dyes, forming randomly arranged resonators which support coherent laser modes. The narrow emission line widths of 0.13 nm or below suggest that gold nanostars provide an efficient coherent feedback for random lasers over an extensive range of wavelengths, all together spanning almost a full optical octave from yellow to infrared.

K-space image correlation to probe the intracellular dynamics of gold nanoparticles

The collective action of dynein, kinesin and myosin molecular motors is responsible for the intracellular active transport of cargoes, vesicles and organelles along the semi-flexible oriented filaments of the cytoskeleton. The overall mobility of the cargoes upon binding and unbinding to motor proteins can be modeled as an intermittency between Brownian diffusion in the cell cytoplasm and active ballistic excursions along actin filaments or microtubules. Such an intermittent intracellular active transport, exhibited by star-shaped gold nanoparticles (GNSs, Gold Nanostars) upon internalization in HeLa cancer cells, is investigated here by combining live-cell time-lapse confocal reflectance microscopy and the spatio-temporal correlation, in the reciprocal Fourier space, of the acquired image sequences. At first, the analytical theoretical framework for the investigation of a two-state intermittent dynamics is presented for Fourier-space Image Correlation Spectroscopy (kICS). Then simulated kICS correlation functions are employed to evaluate the influence of, and sensitivity to, all the kinetic and dynamic parameters the model involves (the transition rates between the diffusive and the active transport states, the diffusion coefficient and drift velocity of the imaged particles). The optimal procedure for the analysis of the experimental data is outlined and finally exploited to derive whole-cell maps for the parameters underlying the GNSs super-diffusive dynamics. Applied here to the GNSs subcellular trafficking, the proposed kICS analysis can be adopted for the characterization of the intracellular (super-) diffusive dynamics of any fluorescent or scattering biological macromolecule.

Role of Collagen Concentration in Stability of Star-Shaped Silver@Gold Nanoparticles

In this report, star-shaped silver@gold (Ag@Au) nanoparticles were synthesized in collagen (Coll) suspensions by a seeding growth approach. The silver nanoparticles were used as seeds for Au development. Coll was used as a protecting agent and the effect of its concentration on stability was also examined. Obtained nanoparticles were then characterized by UV-Vis, TEM, XRD and FTIR. The result was confirmed by the maximum surface plasmon resonance peak at 566-580 nm for each sample indicating the formation of branched Ag@Au@Coll NPs. The average diameters of the branched Ag@Au@Coll NPs were revealed to be 30-50 nm depending on the corresponding component ratio and the pH value. It is interesting to note that the concentration of Coll plays a critical role in the stability of the star-shaped gold nanoparticles. The results offer an understanding of the handling of the electronic and the silver@gold based nanoparticles stability properties.