visible-light-induced-reduction-graphene-oxide-using-plasmonic

Visible-light Induced Reduction of Graphene Oxide Using Plasmonic Nanoparticle

Present work demonstrates the simple, chemical free, fast, and energy efficient method to produce reduced graphene oxide (r-GO) solution at RT using ...

2-Bromobenzaldehydes react with arylhydrazines in toluene at 100 [degree]C in the presence of a catalytic amount of a palladium catalyst and phosphorus chelating ligands such as 1,1[prime or minute]-bis(diphenylphosphino)ferrocene and 1,3-bis(diphenylphosphino)propane along with NaO-t-Bu to afford 1-aryl-1H-indazoles in good yields.

Facile palladium-catalysed synthesis of 1-aryl-1H-indazoles from 2-bromobenzaldehydes and arylhydrazines.

The commercially available formulation of amlodipine is conjugated with besylate salt to increase water solubility. Recently, a new amlodipine salt formulation has been developed in which the free base of amlodipine is conjugated with a chemically different salt, adipate.

Clinic blood pressure responses to two amlodipine salt formulations, adipate and besylate, in adult Korean patients with mild to moderate hypertension: a multicenter, randomized, double-blind, parallel-group, 8-week comparison.

Klinik Blutdruck Antworten auf zwei Amlodipin Salzformulierungen, Adipat und Besylat, bei erwachsenen koreanischen Patienten mit leichter bis mittelschwerer Hypertonie: eine multizentrische, randomisierte, doppelblinde, Parallelgruppen-, 8-Wochen-Vergleich.

Dramatic progress has been made over the recent decade in the applications of metallic nanoparticles in the field of biomolecule detection. The useful physical and chemical properties (e.g., availability of various synthetic methods of size- and shape-controlled nanoparticles, size- and shape-dependent optical properties, availability of various surface chemistries and biocompatibility) of metallic nanoparticles have brought development to the ultrasensitive detection of biomolecules at the attomolar level and this sensitivity enables the diagnosis of otherwise undetectable biomarkers of many fatal diseases, including Alzheimer's disease. Furthermore, coupled with the strong physical properties and biocompatible nature of gold nanoparticles in in vivo conditions, the scope of applications for these particles have been broadened into the field of in vivo imaging, such as X-ray contrasting agents, and also cellular tracking. Here, we review synthetic methods and optical properties of metallic nanoparticles and their use in ultrasensitive, in vitro and in vivo biodiagnostic methods.

Ultrasensitive optical biodiagnostic methods using metallic nanoparticles.

Here, we synthesized highly stable DNA-embedded Au/Ag core-shell nanoparticles (NPs) by a straightforward silver-staining of DNA-modified Au nanoparticles (AuNPs); unlike conventional DNA-surface modified NPs that present particle stability issues, DNA-embedded core-shell NPs offer an extraordinary stability with nanoscale controllability of silver shell thickness; these DNA-embedded core-shell NPs show excellent biorecognition properties and Ag shell-thickness-based optical properties, distinctively different from those of a mixture of AuNPs and AgNPs or Ag/Au alloy nanoparticles.

DNA-embedded Au/Ag core-shell nanoparticles.

Surface-enhanced Raman scattering (SERS)-based signal amplification and detection methods using plasmonic nanostructures have been widely investigated for imaging and sensing applications. However, SERS-based molecule detection strategies have not been practically useful because there is no straightforward method to synthesize and characterize highly sensitive SERS-active nanostructures with sufficiently high yield and efficiency, which results in an extremely low cross-section area in Raman sensing. Here, we report a high-yield synthetic method for SERS-active gold-silver core-shell nanodumbbells, where the gap between two nanoparticles and the Raman-dye position and environment can be engineered on the nanoscale. Atomic-force-microscope-correlated nano-Raman measurements of individual dumbbell structures demonstrate that Raman signals can be repeatedly detected from single-DNA-tethered nanodumbbells. These programmed nanostructure fabrication and single-DNA detection strategies open avenues for the high-yield synthesis of optically active smart nanoparticles and structurally reproducible nanostructure-based single-molecule detection and bioassays.

Nanogap-engineerable Raman-active nanodumbbells for single-molecule detection.

A gold nanoparticle-based colorimetric antibody structure and activity evaluation method is developed without using complicated and expensive instrumentation. In this assay, a minimum number of antibodies to stabilize nanoparticles are conjugated to gold nanoparticles to prepare minimally stable nanoparticle probes, and the addition of salt rapidly induced particle aggregation and a color change of the solution from red to blue (25-min assay time). It is found that the solution color change is affected by the degree of structural denaturation of antibodies, and the conformational change of antibodies affects the modification of antibodies to nanoparticles and particle stability. Importantly, the colorimetric method can be applied to different types of antibodies (IgG, IgA, and IgM) and it shows comparable or better structural sensitivity than conventional circular dichroism spectroscopy. Moreover, immunoassay results show that these structural changes of antibodies are highly correlated with their antigen-binding activities. Rapid particle aggregation and high structural sensitivity are achieved in this assay because particles are modified with a minimum number of antibodies to stabilize particles in solution. This nanoparticle-based colorimetric method could be useful in evaluating the structural and activity changes of an array of antibodies in an easy, rapid, and sensitive manner.

Minimally stable nanoparticle-based colorimetric assay for simple, rapid, and sensitive antibody structure and activity evaluation.

An ideal surface-enhanced Raman scattering (SERS) nanostructure for sensing and imaging applications should induce a high signal enhancement, generate a reproducible and uniform response, and should be easy to synthesize. Many SERS-active nanostructures have been investigated, but they suffer from poor reproducibility of the SERS-active sites, and the wide distribution of their enhancement factor values results in an unquantifiable SERS signal. Here, we show that DNA on gold nanoparticles facilitates the formation of well-defined gold nanobridged nanogap particles (Au-NNP) that generate a highly stable and reproducible SERS signal. The uniform and hollow gap (∼1 nm) between the gold core and gold shell can be precisely loaded with a quantifiable amount of Raman dyes. SERS signals generated by Au-NNPs showed a linear dependence on probe concentration (R(2) > 0.98) and were sensitive down to 10 fM concentrations. Single-particle nano-Raman mapping analysis revealed that >90% of Au-NNPs had enhancement factors greater than 1.0 × 10(8), which is sufficient for single-molecule detection, and the values were narrowly distributed between 1.0 × 10(8) and 5.0 × 10(9).

Highly uniform and reproducible surface-enhanced Raman scattering from DNA-tailorable nanoparticles with 1-nm interior gap.

Obtaining a strong and reproducible surface-enhanced Raman scattering (SERS) signal with a narrow distribution of the high SERS enhancement factor (EF) values from the plasmonic nanostructures is critical for better understanding and practical use of the single-molecule SERS (SMSERS) nanoprobes. In this regard, the systematic and thorough studies about the relationships between single-molecule SERS intensity, EF distribution over many particles, inter-particle distance, particle size/shape/composition and excitation laser wavelength are needed. Here, we extensively studied these relationships using the single-particle AFM-correlated Raman measurement method with two different single-DNA-tethered Au-Ag core-shell nanodumbbell (GSND) designs with engineerable nanogap - the GSND-I with various inter-particle nanogaps from ~4.8 nm to <1 nm or with no gap and the GSND-II with the fixed inter-particle gap size and varying particle size for various size of GSND-II particles from a 23 nm-30 nm pair to a 50 nm-60 nm pair. From the GSND-I probes, we learned that synthesizing <1 nm gap is a key to obtain strong SMSERS signals with a narrow EF value distribution. Importantly, in the case of the GSND-I with <1 nm inter-particle gap, an EF value of as high as 5.9Ã—1013 (average value = 1.8Ã—1013) was obtained and the EF values of analyzed particles were narrowly distributed between 1.9Ã—1012 and 5.9Ã—1013. In the case of the GSND-II probes, a combination of >50 nm Au cores and 514.5 nm laser wavelength that matches well with Ag shell generated stronger SMSERS signals with a more narrow EF distribution than <50 nm Au cores with 514.5 nm laser or the GSND-II structures with 632.8 nm laser. Our results show the usefulness and flexibility of these GSND structures in studying and obtaining SMSERS structures with a narrow distribution of high EF values and the GSNDs are promising SERS probes with highly sensitive and quantitative detection capability when optimally designed.

Tuning and Maximizing the Single-Molecule Surface-Enhanced Raman Scattering from DNA-Tethered Nanodumbbells.

Erlangung einer starken und reproduzierbare Surface enhanced Raman, die Streuung (SERS) Signal mit einer engen Verteilung der hohen SERS Verst&auml;rkung Faktor (EF) Werte aus der plasmonic Nanostrukturen f&uuml;r besseres Verst&auml;ndnis und praktische Nutzung der Einzelmolek&uuml;l-SERS (SMSERS) Nanoprobes von entscheidender Bedeutung ist. In diesem Zusammenhang werden die systematischen und gr&uuml;ndlichen Studien &uuml;ber die Beziehungen zwischen Einzelmolek&uuml;l-SERS Intensit&auml;t, EF-Verteilung &uuml;ber viele Teilchen, inter-particle Entfernung, Partikel Gr&ouml;&szlig;e/Form/Komposition und Erregung Laser Wellenl&auml;nge ben&ouml;tigt. Hier haben wir ausgiebig studiert diese Beziehungen, der mit das Einzel-Partikel AFM korrelierte Raman-Messmethode mit zwei Einzel-DNA-gefesselte Au-Ag Core-Shell-Nanodumbbell (GSND) Ausf&uuml;hrungen mit engineerable Nanogap - die GSND-I mit verschiedenen inter-particle Nanogaps von ~4.8 nm bis &lt; 1 nm oder mit keine L&uuml;cke und dem GSND-II mit festen inter-particle L&uuml;cke Gr&ouml;&szlig;e und unterschiedlicher Korngr&ouml;&szlig;e f&uuml;r verschiedene Gr&ouml;&szlig;e der GSND-II Teilchen aus einem 23 nm-30 nm-Paar mit einem 50-nm-60 nm-Paar. Aus der GSND-ich-Sonden, haben wir gelernt, dass Synthese &lt; 1 nm-L&uuml;cke ist ein Schl&uuml;ssel zu starke SMSERS-Signale mit einer engen Verteilung der EF Wert zu erhalten. Wichtig ist, bei der GSND-I mit &lt; 1 nm inter-particle Gap, einem EF-wert von bis zu 5,9 &times; 1013 (mittelwert = 1,8 &times; 1013) erworben wurde und die EF-werte der untersuchten teilchen waren eng zwischen 1,9 &times; 1012 und 5,9 &times; 1013. bei der GSND-II-sonden, eine kombination aus &gt; 50 nm Au Kerne und 514,5 nm-Laser-Wellenl&auml;nge, die gut mit Ag-Shell entspricht erzeugt st&auml;rkere SMSERS Signale mit einer engeren EF-Verbreitung als &lt; 50 nm Au Kerne mit 514,5 nm Laser oder die GSND-II-Strukturen mit 632,8 nm Laser. Unsere Ergebnisse zeigen die N&uuml;tzlichkeit und die Flexibilit&auml;t dieser GSND-Strukturen in Studium und Beschaffung SMSERS Strukturen mit einer engen Verteilung hoher EF-Werte und die GSNDs sind viel versprechend SERS-Sonden mit hochempfindliche und quantitative Detektionsverm&ouml;gen wenn optimal ausgelegt.

Tuning und Maximierung der Einzelmolek&uuml;l-Surface Enhanced Raman-Streuung durch DNA-gefesselte Nanodumbbells.

Reactive oxygen and nitrogen species (ROS and RNS) are continuously produced in the cellular systems and are controlled by several antioxidant mechanisms. Here, we developed a straightforward, sensitive, and quantitative assay for the colorimetric and spectroscopic detection of various ROS and RNS such as H2O2, ·OH, (-)OCl, NO·, and O2(-) using glutathione-modified gold nanoparticles (GSH-AuNPs). A basic principle here is that the GSHs on the AuNP surface can be readily detached via the formation of glutathione disulfides upon the addition of ROS and RNS, and destabilized particles can aggregate to generate the plasmonic couplings between plasmonic AuNPs that trigger the red shift in UV-vis spectrum and solution color change. For nonradical species such as H2O2, this process can be more efficiently achieved by converting them into radical species via the Fenton reaction. Using this strategy, we were able to rapidly and quantitatively distinguish among cancerous and normal cells based on ROS and RNS production.

Glutathione dimerization-based plasmonic nanoswitch for biodetection of reactive oxygen and nitrogen species.

We report plasmonic gold nanoshells and nanorods coated with reduced graphene oxide that produce an enhanced photothermal effect when stimulated by near-infrared (NIR) light. Electrostatic interactions between nanosized graphene oxide and gold nanoparticles followed by in situ chemical reduction generated reduced graphene oxide-coated nanoparticles; the coating was demonstrated using Raman and HR-TEM. Reduced graphene oxide-coated gold nanoparticles showed enhanced photothermal effect compared to noncoated or nonreduced graphene oxide-coated gold nanoparticles. Reduced graphene oxide-coated gold nanoparticles killed cells more rapidly than did noncoated or nonreduced graphene oxide-coated gold nanoparticles.

Enhanced photothermal effect of plasmonic nanoparticles coated with reduced graphene oxide.

The design, synthesis and control of plasmonic nanostructures, especially with ultrasmall plasmonically coupled nanogap (∼1 nm or smaller), are of significant interest and importance in chemistry, nanoscience, materials science, optics and nanobiotechnology. Here, we studied and established the thiolated DNA-based synthetic principles and methods in forming and controlling Au core-nanogap-Au shell structures [Au-nanobridged nanogap particles (Au-NNPs)] with various interior nanogap and Au shell structures. We found that differences in the binding affinities and modes among four different bases to Au core, DNA sequence, DNA grafting density and chemical reagents alter Au shell growth mechanism and interior nanogap-forming process on thiolated DNA-modified Au core. Importantly, poly A or poly C sequence creates a wider interior nanogap with a smoother Au shell, while poly T sequence results in a narrower interstitial interior gap with rougher Au shell, and on the basis of the electromagnetic field calculation and experimental results, we unraveled the relationships between the width of the interior plasmonic nanogap, Au shell structure, electromagnetic field and surface-enhanced Raman scattering. These principles and findings shown in this paper offer the fundamental basis for the thiolated DNA-based chemistry in forming and controlling metal nanostructures with ∼1 nm plasmonic gap and insight in the optical properties of the plasmonic NNPs, and these plasmonic nanogap structures are useful as strong and controllable optical signal-generating nanoprobes.

Thiolated DNA-based chemistry and control in the structure and optical properties of plasmonic nanoparticles with ultrasmall interior nanogap.

Here we report a new and efficient synthetic method for reduced graphene oxide using visible-light and plasmonic nanoparticles at room temperature. The r-GO prepared using visible light showed excellent fluorescence quenching properties and target detection capabilities.

Plasmon-assisted and visible-light induced graphene oxide reduction and efficient fluorescence quenching.

We report a method to achieve high speed and high resolution live cell Raman images using small spherical gold nanoparticles with highly narrow intra-nanogap structures responding to NIR excitation (785 nm) and high-speed confocal Raman microscopy. The three different Raman-active molecules placed in the narrow intra-nanogap showed a strong and uniform Raman intensity in solution even under transient exposure time (10 ms) and low input power of incident laser (200 μW), which lead to obtain high-resolution single cell image within 30 s without inducing significant cell damage. The high resolution Raman image showed the distributions of gold nanoparticles for their targeted sites such as cytoplasm, mitochondria, or nucleus. The high speed Raman-based live cell imaging allowed us to monitor rapidly changing cell morphologies during cell death induced by the addition of highly toxic KCN solution to cells. These results strongly suggest that the use of SERS-active nanoparticle can greatly improve the current temporal resolution and image quality of Raman-based cell images enough to obtain the detailed cell dynamics and/or the responses of cells to potential drug molecules.

High resolution live cell Raman imaging using subcellular organelle-targeting SERS-sensitive gold nanoparticles with highly narrow intra-nanogap.

We report a strongly amplified photoacoustic (PA) performance of the new functional hybrid material composed of reduced graphene oxide and gold nanorods. Due to the excellent NIR light absorption properties of the reduced graphene oxide coated gold nanorods (r-GO-AuNRs) and highly efficient heat transfer process through the reduced graphene oxide layer, r-GO-AuNRs exhibit excellent photothermal stability and significantly higher photoacoustic amplitudes than those of bare-AuNRs, nonreduced graphene oxide coated AuNRs (GO-AuNRs), or silica-coated AuNR, as demonstrated in both in vitro and in vivo systems. The linear response of PA amplitude from reduced state controlled GO on AuNR indicates the critical role of GO for a strong photothermal effect of r-GO-AuNRs. Theoretical studies with finite-element-method lab-based simulation reveal that a 4 times higher magnitude of the enhanced electromagnetic field around r-GO-AuNRs can be generated compared with bare AuNRs or GO-AuNRs. Furthermore, the r-GO-AuNRs are expected to be a promising deep-tissue imaging probe because of extraordinarily high PA amplitudes in the 4-11 MHz operating frequency of an ultrasound transducer. Therefore, the r-GO-AuNRs can be a useful imaging probe for highly sensitive photoacoustic images and NIR sensitive therapeutics based on a strong photothermal effect.

Amplified photoacoustic performance and enhanced photothermal stability of reduced graphene oxide coated gold nanorods for sensitive photoacoustic imaging.

Article	Year
Facile palladium-catalysed synthesis of 1-aryl-1H-indazoles from 2-bromobenzaldehydes and arylhydrazines. Chemical communications (Cambridge, England)\| PubMed ID: 14737353	2004
Clinic blood pressure responses to two amlodipine salt formulations, adipate and besylate, in adult Korean patients with mild to moderate hypertension: a multicenter, randomized, double-blin... Clinical therapeutics\| PubMed ID: 16117979	2005
Ultrasensitive optical biodiagnostic methods using metallic nanoparticles. Nanomedicine (London, England)\| PubMed ID: 18373427	2008
DNA-embedded Au/Ag core-shell nanoparticles. Chemical communications (Cambridge, England)\| PubMed ID: 18985194	2008
Nanogap-engineerable Raman-active nanodumbbells for single-molecule detection. Nature materials\| PubMed ID: 20010829	2010
Minimally stable nanoparticle-based colorimetric assay for simple, rapid, and sensitive antibody structure and activity evaluation. Small (Weinheim an der Bergstrasse, Germany)\| PubMed ID: 21308990	2011
Highly uniform and reproducible surface-enhanced Raman scattering from DNA-tailorable nanoparticles with 1-nm interior gap. Nature nanotechnology\| PubMed ID: 21623360	2011
Tuning and Maximizing the Single-Molecule Surface-Enhanced Raman Scattering from DNA-Tethered Nanodumbbells. ACS nano\| PubMed ID: 23036132	2012
Glutathione dimerization-based plasmonic nanoswitch for biodetection of reactive oxygen and nitrogen species. ACS nano\| PubMed ID: 23448129	2013
Enhanced photothermal effect of plasmonic nanoparticles coated with reduced graphene oxide. Nano letters\| PubMed ID: 23899267	2013
Thiolated DNA-based chemistry and control in the structure and optical properties of plasmonic nanoparticles with ultrasmall interior nanogap. Journal of the American Chemical Society\| PubMed ID: 25198151	2014
Plasmon-assisted and visible-light induced graphene oxide reduction and efficient fluorescence quenching. Chemical communications (Cambridge, England)\| PubMed ID: 25233877	2014
High resolution live cell Raman imaging using subcellular organelle-targeting SERS-sensitive gold nanoparticles with highly narrow intra-nanogap. Nano letters\| PubMed ID: 25646716	2015
Amplified photoacoustic performance and enhanced photothermal stability of reduced graphene oxide coated gold nanorods for sensitive photoacoustic imaging. ACS nano\| PubMed ID: 25751167	2015

Dong-Kwon Lim

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