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A robust and competitive technology to synthesize arranged high-density gold nanoparticles on highly uniform Al nanoconcavities substrates is presented. The nanoparticles are formed through sputtering and thermal annealing treatment on Al templates, which are synthesized through particular removal of nanoporous anodic alumina structure with controlled anodization conditions and with phosphoric acid as electrolyte. This scalable fabrication mechanism regulates the particle size, arrangement, shape and interparticle separation across large surface areas, which empowers the optimization of their surface enhanced Raman scattering (SERS) activities. 4-mercaptopyridine is selected as a probe molecule. Analysis reveals that Au-decorated Al nanoconcavities substrates are highly competitive for the enhancement of Raman signals and could be employed as self-sustaining nanosensors. By using these templates, a concentration as low as 10−7 M of 4-mercaptopyridine is easily detected. Finally, the calculated EF factor of 1.1 × 107 confirms the suitability for effective and sensitive SERS detection of the developed substrates.

An inexpensive virus detection scheme with high sensitivity and specificity is desirable for broad applications such as the COVID-19 virus. In this article, we introduce the localized surface plasmon resonance (LSPR) principle on the aggregation of antigen-coated gold nanoparticles (GNPs) to detect SARS-CoV-2 Nucleocapsid (N) proteins. Experiments show this technique can produce results observable by the naked eye in 5 min with a LOD (Limits of Detection) of 150 ng/ml for the N proteins. A comprehensive numerical model of the LSPR effect on the aggregation of GNPs has been developed to identify the key parameters in the reaction processes. The color-changing behaviors can be readily utilized to detect the existence of the virus while the quantitative concentration value is characterized with the assistance of an optical spectrometer. A parameter defined as the ratio of the light absorption intensity at the upper visible band region of 700 nm to the light absorption intensity at the peak optical absorption spectrum of the GNPs at 530 nm is found to have a linear relationship with respect to the N protein concentrations. As such, this scheme could be utilized as an inexpensive testing methodology for applications in POC (Point-of-Care) diagnostics to combat current and future virus-induced pandemics.

The ongoing emergence of severe acute respiratory syndrome caused by the new coronavirus (SARS-CoV-2) variants requires swift actions in identifying specific antigens and optimizing vaccine development to maximize the humoral response of the patient. Measuring the specificity and the amount of antibody produced by the host immune system with high throughput and accuracy is critical to develop timely diagnostics and therapeutic strategies. Motivated by finding an easy-to-use and cost-effective alternative to existing serological methodologies for multiplex analysis, we develop a proof-of-concept multiplex nanoplasmonic biosensor to capture the humoral response in serums against multiple antigens. Nanoplasmonic sensing relies on the wavelength shift of the localized surface plasmon resonance (LSPR) peak of gold nanostructures upon binding interactions between the antibodies and the immobilized antigens. Here the antigens are first immobilized on different sensing areas by using a mono-biotinylation system based on the high affinity interaction between biotin and streptavidin. We then validate the multiplex platform by detecting the presence of 3 monoclonal antibodies against 3 antigens (2 different hemagglutinins (HAs) from influenza viruses, and the SARS-CoV-2 Spike RBD (receptor binding domain)). We also measure the humoral response in murine sera collected before and after its immunization with the SARS-CoV-2 Spike protein, in good agreement with the results obtained by the ELISA assay. Our nanoplasmonic assays have successfully demonstrated multiple serum antibody profiling, which can be further integrated with microfluidics as an effective high throughput screening platform in future studies for the ongoing SARS-CoV-2 vaccine development., source:https://www.sciencedirect.com/science/article/pii/S0956566322002330

An inexpensive virus detection scheme with high sensitivity and specificity is desirable for broad applications such as the COVID-19 virus. In this article, we introduce the localized surface plasmon resonance (LSPR) principle on the aggregation of antigen-coated gold nanoparticles (GNPs) to detect SARS-CoV-2 Nucleocapsid (N) proteins. Experiments show this technique can produce results observable by the naked eye in 5 min with a LOD (Limits of Detection) of 150 ng/ml for the N proteins. A comprehensive numerical model of the LSPR effect on the aggregation of GNPs has been developed to identify the key parameters in the reaction processes. The color-changing behaviors can be readily utilized to detect the existence of the virus while the quantitative concentration value is characterized with the assistance of an optical spectrometer. A parameter defined as the ratio of the light absorption intensity at the upper visible band region of 700 nm to the light absorption intensity at the peak optical absorption spectrum of the GNPs at 530 nm is found to have a linear relationship with respect to the N protein concentrations. As such, this scheme could be utilized as an inexpensive testing methodology for applications in POC (Point-of-Care) diagnostics to combat current and future virus-induced pandemics.

Photo-thermo catalysis can effectively reduce the reaction temperature of dry reforming of methane (DRM) and increase the reaction efficiency. The development of a new type of high-efficiency photo-thermo catalyst and the exploration of its catalytic mechanism are the focuses of current research. A self-confinement strategy was used to prepare nickel-iridium bimetallic catalyst (Ni-Ir/SiO2). Catalyst physicochemical properties and photo-thermo catalytic performances on DRM were both studied. The results show that the bimetal nanoparticle has an average size of less than 3.5 nm and is evenly distributed on the substrate. The light absorption ability of the constructed ultra-small nickel-iridium bimetal is significantly enhanced. At the same time, the electrical field is also enhanced to effectively promote the hot electron excitation and realize its activation of methane and carbon dioxide molecules, especially their dissociation below the thermodynamic equilibrium temperature. In addition, the external heating of the system can further improve DRM reaction rate. Under the conditions of 700℃ and light intensity of 5 W/cm2, the H2 yield reaches 861 mmol/(g h), equivalent to that of the pure noble metal-based catalysts. Also, the catalyst shows good repeatability in the photo-thermo catalytic DRM reaction.

The ongoing global pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to active research in its associated diagnostics and medical treatments. While quantitative reverse transcription polymerase chain reaction (qRT-PCR) is the most reliable method to detect viral genes of SARS-CoV-2, serological tests for specific antiviral antibodies are also important as they identify false negative qRT-PCR responses, track how effectively the patient's immune system is fighting the infection, and are potentially helpful for plasma transfusion therapies. In this work, based on the principle of localized surface plasmon resonance (LSPR), we develop an opto-microfluidic sensing platform with gold nanospikes, fabricated by electrodeposition, to detect the presence and amount of antibodies specific to the SARS-CoV-2 spike protein in 1 mu L of human plasma diluted in 1 mL of buffer solution, within similar to 30 min. The target antibody concentration can be correlated with the LSPR wavelength peak shift of gold nanospikes caused by the local refractive index change due to the antigen-antibody binding. This label-free microfluidic platform achieves a limit of detection of similar to 0.08 ng/mL (similar to 0.5 pM), falling under the clinical relevant concentration range. We demonstrate that our opto-microfluidic platform offers a promising point-of-care testing tool to complement standard serological assays and make SARS-CoV-2 quantitative diagnostics easier, cheaper, and faster., source:https://www.sciencedirect.com/science/article/pii/S0956566320305686

Photo-thermo catalysis can effectively reduce the reaction temperature of dry reforming of methane (DRM) and increase the reaction efficiency. The development of a new type of high-efficiency photo-thermo catalyst and the exploration of its catalytic mechanism are the focuses of current research. A self-confinement strategy was used to prepare nickel-iridium bimetallic catalyst (Ni-Ir/SiO2). Catalyst physicochemical properties and photo-thermo catalytic performances on DRM were both studied. The results show that the bimetal nanoparticle has an average size of less than 3.5 nm and is evenly distributed on the substrate. The light absorption ability of the constructed ultra-small nickel-iridium bimetal is significantly enhanced. At the same time, the electrical field is also enhanced to effectively promote the hot electron excitation and realize its activation of methane and carbon dioxide molecules, especially their dissociation below the thermodynamic equilibrium temperature. In addition, the external heating of the system can further improve DRM reaction rate. Under the conditions of 700℃ and light intensity of 5 W/cm2, the H2 yield reaches 861 mmol/(g h), equivalent to that of the pure noble metal-based catalysts. Also, the catalyst shows good repeatability in the photo-thermo catalytic DRM reaction.

Utilization of the renewable energy sources is one of the main challenges in the state-of-the-art technologies for CO recycling. Here we have taken advantage of the solar light harvesting in the thermocatalytic approach to carbon dioxide methanation. The large-surface-area Ni/CeO catalyst produced by a scalable low-cost method was characterized and tested in the dark and under solar light irradiation conditions. Light-assisted CO conversion experiments as well as in-situ DRIFT spectrometry, performed at different illumination intensities, have revealed a dual effect of the incident photons on the catalytic properties of the two-component Ni/CeO catalyst. On the one hand, absorbed photons induce a localized surface plasmon resonance in the Ni nanoparticles followed by dissipation of the heat to the oxide matrix. On the other hand, the illumination activates the photocatalytic properties of the CeO support, which leads to an increase in the concentration of the intermediates being precursor for methane production. Analysis of the methane production at different temperatures and illumination conditions has shown that the methanation reaction in our case is controlled by a photothermally-activated process. The used approach has allowed us to increase the reaction rate up to 2.4 times and consequently to decrease the power consumption by 20 % under solar illumination, thus replacing the conventional thermal activation of the reaction with a green energy source.

Noble metal (NM)-modified wide-bandgap semiconductors with activity under visible light (Vis) irradiation, due to localized surface plasmon resonance (LSPR), known as plasmonic photocatalysts, have been intensively studied over the last few years. Despite the novelty of the topic, a large number of reports have already been published, discussing the optimal properties, synthesis methods and mechanism clarification. It has been proposed that both efficient light harvesting and charge carriers’ migration are detrimental for high and stable activity under Vis irradiation. Accordingly, photonic crystals (PCs) with photonic bandgap (PBG) and slow photon effects seem to be highly attractive for efficient use of incident photons. Therefore, the study on PCs-based plasmonic photocatalysts has been conducted, mainly on titania inverse opal (IO) modified with nanoparticles (NPs) of NM. Although, the research is quite new and only several reports have been published, it might be concluded that the matching between LSPR and PBG (especially at red edge) by tuning of NMNPs size and IO-void diameter, respectively, is the most crucial for the photocatalytic activity.

Wide-bandgap semiconductors modified with nanostructures of noble metals for photocatalytic activity under vis irradiation due to localized surface plasmon resonance (LSPR), known as plasmonic photocatalysts, have been intensively investigated over the last decade. Most literature reports discuss the properties and activities of plasmonic photocatalysts for the decomposition of organic compounds and solar energy conversion. Although noble metals, especially silver and copper, have been known since ancient times as excellent antimicrobial agents, there are only limited studies on plasmonic photocatalysts for the inactivation of microorganisms (considering vis-excitation). Accordingly, this review has discussed the available literature reports on microbiological applications of plasmonic photocatalysis, including antibacterial, antiviral and antifungal properties, and also a novel study on other microbiological purposes, such as cancer treatment and drug delivery. Although some reports indicate high antimicrobial properties of these photocatalysts and their potential for medical/pharmaceutical applications, there is still a lack of comprehensive studies on the mechanism of their interactions with microbiological samples. Moreover, contradictory data have also been published, and thus more study is necessary for the final conclusions on the key-factor properties and the mechanisms of inactivation of microorganisms and the treatment of cancer cells.

Wide-bandgap semiconductors modified with nanostructures of noble metals for photocatalytic activity under vis irradiation due to localized surface plasmon resonance (LSPR), known as plasmonic photocatalysts, have been intensively investigated over the last decade. Most literature reports discuss the properties and activities of plasmonic photocatalysts for the decomposition of organic compounds and solar energy conversion. Although noble metals, especially silver and copper, have been known since ancient times as excellent antimicrobial agents, there are only limited studies on plasmonic photocatalysts for the inactivation of microorganisms (considering vis-excitation). Accordingly, this review has discussed the available literature reports on microbiological applications of plasmonic photocatalysis, including antibacterial, antiviral and antifungal properties, and also a novel study on other microbiological purposes, such as cancer treatment and drug delivery. Although some reports indicate high antimicrobial properties of these photocatalysts and their potential for medical/pharmaceutical applications, there is still a lack of comprehensive studies on the mechanism of their interactions with microbiological samples. Moreover, contradictory data have also been published, and thus more study is necessary for the final conclusions on the key-factor properties and the mechanisms of inactivation of microorganisms and the treatment of cancer cells.

Noble metal (NM)-modified wide-bandgap semiconductors with activity under visible light (Vis) irradiation, due to localized surface plasmon resonance (LSPR), known as plasmonic photocatalysts, have been intensively studied over the last few years. Despite the novelty of the topic, a large number of reports have already been published, discussing the optimal properties, synthesis methods and mechanism clarification. It has been proposed that both efficient light harvesting and charge carriers’ migration are detrimental for high and stable activity under Vis irradiation. Accordingly, photonic crystals (PCs) with photonic bandgap (PBG) and slow photon effects seem to be highly attractive for efficient use of incident photons. Therefore, the study on PCs-based plasmonic photocatalysts has been conducted, mainly on titania inverse opal (IO) modified with nanoparticles (NPs) of NM. Although, the research is quite new and only several reports have been published, it might be concluded that the matching between LSPR and PBG (especially at red edge) by tuning of NMNPs size and IO-void diameter, respectively, is the most crucial for the photocatalytic activity.

Wide-bandgap semiconductors modified with nanostructures of noble metals for photocatalytic activity under vis irradiation due to localized surface plasmon resonance (LSPR), known as plasmonic photocatalysts, have been intensively investigated over the last decade. Most literature reports discuss the properties and activities of plasmonic photocatalysts for the decomposition of organic compounds and solar energy conversion. Although noble metals, especially silver and copper, have been known since ancient times as excellent antimicrobial agents, there are only limited studies on plasmonic photocatalysts for the inactivation of microorganisms (considering vis-excitation). Accordingly, this review has discussed the available literature reports on microbiological applications of plasmonic photocatalysis, including antibacterial, antiviral and antifungal properties, and also a novel study on other microbiological purposes, such as cancer treatment and drug delivery. Although some reports indicate high antimicrobial properties of these photocatalysts and their potential for medical/pharmaceutical applications, there is still a lack of comprehensive studies on the mechanism of their interactions with microbiological samples. Moreover, contradictory data have also been published, and thus more study is necessary for the final conclusions on the key-factor properties and the mechanisms of inactivation of microorganisms and the treatment of cancer cells.

This dissertation presents three different projects aimed at understanding how fabrication, functionalization, and arrangement of nanostructures relates to their resulting properties. The composition, dimensions, and arrangement of nanoparticles and nanostructures are particularly significant for controlling the properties of magnetic nanoparticles, optical nanostructures, and directed assemblies of gold nanoparticles. Chapter 2 of this thesis demonstrates how the size and composition of ferrite nanoparticles are directly linked to the unique magnetic properties they exhibit, and how with further functionalization, these nanoparticles can be modified for future biological applications. Magnetic ferrite nanoparticles were synthesized at various sizes, 10 and 40 nm, and then post-synthetically modified with a hydrophilic polyacrylic acid coating before further incorporation of these nanoparticles into biologically relevant systems such as poly-lysine and polyacrylic acid hydrogels. In Chapter 3, we look at the reduction of electrochromic WO3 and its arrangement within highly patterned nanostructured arrays, which we anticipate will exhibit localized surface plasmon resonance (LSPR) in an effort to develop powerful new surfaces for light-based sensing applications in the near infrared. Several post-fabrication modification techniques, including furnace reduction and MoO3 doping, were explored to create permanent reduced states within the WO3 crystal lattice. Finally, Chapter 4 presents our progress in developing improved methodologies to structurally characterize DNA-gold interactions of smaller masses. 1.4 nm nanogold was bound to 60 base-pair thiol-modified DNA strands, purified, and then analyzed through cryo-electron microscopy.

In this thesis, an in-depth study on alloying effect of non-plasmonic metals with gold nanoparticles to selectively control product formation under light and dark conditions was done. Overall, it was demonstrated that fine tuning the alloying effect could enhance product selectivity switch. This may open up a new research pathway for many important organic syntheses.

This dissertation presents three different projects aimed at understanding how fabrication, functionalization, and arrangement of nanostructures relates to their resulting properties. The composition, dimensions, and arrangement of nanoparticles and nanostructures are particularly significant for controlling the properties of magnetic nanoparticles, optical nanostructures, and directed assemblies of gold nanoparticles. Chapter 2 of this thesis demonstrates how the size and composition of ferrite nanoparticles are directly linked to the unique magnetic properties they exhibit, and how with further functionalization, these nanoparticles can be modified for future biological applications. Magnetic ferrite nanoparticles were synthesized at various sizes, 10 and 40 nm, and then post-synthetically modified with a hydrophilic polyacrylic acid coating before further incorporation of these nanoparticles into biologically relevant systems such as poly-lysine and polyacrylic acid hydrogels. In Chapter 3, we look at the reduction of electrochromic WO3 and its arrangement within highly patterned nanostructured arrays, which we anticipate will exhibit localized surface plasmon resonance (LSPR) in an effort to develop powerful new surfaces for light-based sensing applications in the near infrared. Several post-fabrication modification techniques, including furnace reduction and MoO3 doping, were explored to create permanent reduced states within the WO3 crystal lattice. Finally, Chapter 4 presents our progress in developing improved methodologies to structurally characterize DNA-gold interactions of smaller masses. 1.4 nm nanogold was bound to 60 base-pair thiol-modified DNA strands, purified, and then analyzed through cryo-electron microscopy.

With development in the synthesis of shape- and size-dependent gold (Au) nanostructures (NSs) and their applications in nanomedicine, one of the biggest challenges is to understand the interaction of these shapes with cancer cells. Herein, we study the interaction of Au NSs of five different shapes with glioblastoma-astrocytoma cells. Three different shapes (nanorods, tetrahexahedra, and bipyramids), possessing tunable optical properties, have been synthesized by a single-step seed-mediated growth approach employing binary surfactant mixtures of CTAB and a secondary surfactant By the use of two-step seed-mediated approach, we obtained new NSs, named nanomakura (Makura is a Japanese word used for pillow) which is reported for the first time here. Spherical Au nanoparticles were prepared by the Turkevich method. To study NS-cell interactions, we functionalized the NSs using thiolated PEG followed by 11-Mercaptoundecanoic acid. The influence of shape and concentration of NSs on the cytotoxicity were assessed with a LIVE/DEAD assay in glioblastoma-astrocytoma cells. Furthermore, the time-dependent uptake of nanomakura was studied with TEM. Our results indicate that unlike the other shapes studied here, the nanomakura were taken up both via receptor-mediated endocytosis and macropinocytosis. Thus, from our library of different NSs with similar surface functionality, the shape is found to be an important parameter for cellular uptake.

With development in the synthesis of shape- and size-dependent gold (Au) nanostructures (NSs) and their applications in nanomedicine, one of the biggest challenges is to understand the interaction of these shapes with cancer cells. Herein, we study the interaction of Au NSs of five different shapes with glioblastoma-astrocytoma cells. Three different shapes (nanorods, tetrahexahedra, and bipyramids), possessing tunable optical properties, have been synthesized by a single-step seed-mediated growth approach employing binary surfactant mixtures of CTAB and a secondary surfactant By the use of two-step seed-mediated approach, we obtained new NSs, named nanomakura (Makura is a Japanese word used for pillow) which is reported for the first time here. Spherical Au nanoparticles were prepared by the Turkevich method. To study NS-cell interactions, we functionalized the NSs using thiolated PEG followed by 11-Mercaptoundecanoic acid. The influence of shape and concentration of NSs on the cytotoxicity were assessed with a LIVE/DEAD assay in glioblastoma-astrocytoma cells. Furthermore, the time-dependent uptake of nanomakura was studied with TEM. Our results indicate that unlike the other shapes studied here, the nanomakura were taken up both via receptor-mediated endocytosis and macropinocytosis. Thus, from our library of different NSs with similar surface functionality, the shape is found to be an important parameter for cellular uptake.

With development in the synthesis of shape- and size-dependent gold (Au) nanostructures (NSs) and their applications in nanomedicine, one of the biggest challenges is to understand the interaction of these shapes with cancer cells. Herein, we study the interaction of Au NSs of five different shapes with glioblastoma-astrocytoma cells. Three different shapes (nanorods, tetrahexahedra, and bipyramids), possessing tunable optical properties, have been synthesized by a single-step seed-mediated growth approach employing binary surfactant mixtures of CTAB and a secondary surfactant By the use of two-step seed-mediated approach, we obtained new NSs, named nanomakura (Makura is a Japanese word used for pillow) which is reported for the first time here. Spherical Au nanoparticles were prepared by the Turkevich method. To study NS-cell interactions, we functionalized the NSs using thiolated PEG followed by 11-Mercaptoundecanoic acid. The influence of shape and concentration of NSs on the cytotoxicity were assessed with a LIVE/DEAD assay in glioblastoma-astrocytoma cells. Furthermore, the time-dependent uptake of nanomakura was studied with TEM. Our results indicate that unlike the other shapes studied here, the nanomakura were taken up both via receptor-mediated endocytosis and macropinocytosis. Thus, from our library of different NSs with similar surface functionality, the shape is found to be an important parameter for cellular uptake.

A major hurdle in the development of next-generation biosensors is the ability detect single molecules and the use of this detection to form an appropriate assessment of the larger biological system. Once, this has been achieved, it will be possible to build new and more efficient biosensors that can detect subtle concentration changes in early disease stages and, biosensors that no longer require calibration. The unique optical properties of plasmonic nanoparticles offer the possibility to develop single nanoparticle assays that are capable of these ultra-low detection limits. Current spectroscopic techniques can sensitively analyse spectral shifts of these nanoparticles; however, these nanoparticles need to be analysed in a high-throughput manner to obtain a useful assessment of a biological system. This main objective of this thesis was to develop a technique for the sensitive and high-throughput analysis of plasmonic nanoparticles, and the construction of a biosensing interface capable of ultra-sensitive detection. The first stage in this goal was achieved by developing a technique for high-throughput single nanoparticle analysis. The technique utilises a consumer-grade camera and a dark-field microscope to analyse the λmax of several thousands of nanoparticles within a second, without the need for a spectrometer. The development of this digital analysis technique enabled single nanoparticle assays to be performed rapidly. However, to detect at very low concentrations it is necessary to employ a signal enhancement step.Within this work, two signal amplification and detection strategies were explored: i) enzyme-catalysed nanoparticle growth and ii) core-satellite formation for multiplexed detection of DNA. The enzyme-catalysed system was able to grow the nanoparticles and cause a change in LSPR. However, for integration into single nanoparticle assays the enzyme-based amplification strategy needs to be optimised to minimise the background signal. A secon

With development in the synthesis of shape- and size-dependent gold (Au) nanostructures (NSs) and their applications in nanomedicine, one of the biggest challenges is to understand the interaction of these shapes with cancer cells. Herein, we study the interaction of Au NSs of five different shapes with glioblastoma-astrocytoma cells. Three different shapes (nanorods, tetrahexahedra, and bipyramids), possessing tunable optical properties, have been synthesized by a single-step seed-mediated growth approach employing binary surfactant mixtures of CTAB and a secondary surfactant By the use of two-step seed-mediated approach, we obtained new NSs, named nanomakura (Makura is a Japanese word used for pillow) which is reported for the first time here. Spherical Au nanoparticles were prepared by the Turkevich method. To study NS-cell interactions, we functionalized the NSs using thiolated PEG followed by 11-Mercaptoundecanoic acid. The influence of shape and concentration of NSs on the cytotoxicity were assessed with a LIVE/DEAD assay in glioblastoma-astrocytoma cells. Furthermore, the time-dependent uptake of nanomakura was studied with TEM. Our results indicate that unlike the other shapes studied here, the nanomakura were taken up both via receptor-mediated endocytosis and macropinocytosis. Thus, from our library of different NSs with similar surface functionality, the shape is found to be an important parameter for cellular uptake.

With development in the synthesis of shape- and size-dependent gold (Au) nanostructures (NSs) and their applications in nanomedicine, one of the biggest challenges is to understand the interaction of these shapes with cancer cells. Herein, we study the interaction of Au NSs of five different shapes with glioblastoma-astrocytoma cells. Three different shapes (nanorods, tetrahexahedra, and bipyramids), possessing tunable optical properties, have been synthesized by a single-step seed-mediated growth approach employing binary surfactant mixtures of CTAB and a secondary surfactant By the use of two-step seed-mediated approach, we obtained new NSs, named nanomakura (Makura is a Japanese word used for pillow) which is reported for the first time here. Spherical Au nanoparticles were prepared by the Turkevich method. To study NS-cell interactions, we functionalized the NSs using thiolated PEG followed by 11-Mercaptoundecanoic acid. The influence of shape and concentration of NSs on the cytotoxicity were assessed with a LIVE/DEAD assay in glioblastoma-astrocytoma cells. Furthermore, the time-dependent uptake of nanomakura was studied with TEM. Our results indicate that unlike the other shapes studied here, the nanomakura were taken up both via receptor-mediated endocytosis and macropinocytosis. Thus, from our library of different NSs with similar surface functionality, the shape is found to be an important parameter for cellular uptake.

Optical Characterization of Localized Surface Plasmon Resonances in Doped Metal Oxide NanocrystalsbyRobert Walker JohnsDoctor of Philosophy in ChemistryUniversity of California, BerkeleyProfessor Tanja Cuk, Co-Chair Professor Delia Milliron, Co-ChairElectronically doped metal oxide nanocrystals exhibit tunable infrared localized surface plasmon resonances (LSPRs). Semiconductors provide an alternative dielectric environment than metallically bonded solids, such as noble metals, for metallic behavior. The ways in which the electronic structure of the semiconductor and of the dopants used to make them metallic hybridize substantially changes the plasmonic behavior. Choice of dopant element, dopant placement within the nanocrystal, and dopant interaction with other defects in the lattice all lead to changes in the observed optical properties of these nanocrystals. Here, the methods for optical characterization of LSPRs in doped metal oxides are discussed with particular attention directed at how undetermined heterogeneous contributions to ensemble measurements lead to misattributing inhomogenous broadening to poor plasmonic performance. Electronic damping in these materials is incredibly low compared to coinage metals, and they tout the added benefit of spectral tuning through chemical composition rather than morphology. The result is a class of materials that can both have their optical response tuned separately from other application relevant factors like nanocrystal size, and yield high performance LSPR for directing far-field radiation to the near-field. Learning that doped metal oxides have high quality factor LSPR was found through the first single nanocrystal measurements of LSPR made in the mid-IR through the use of near-field optics to interrogate these nanocrystals separately. The result was uncovering substantial nanocrystal-to-nanocrystal variation within batches of nanocrystals making ensemble measurements appear to have broad LSPR, while in fact t

Optical Characterization of Localized Surface Plasmon Resonances in Doped Metal Oxide NanocrystalsbyRobert Walker JohnsDoctor of Philosophy in ChemistryUniversity of California, BerkeleyProfessor Tanja Cuk, Co-Chair Professor Delia Milliron, Co-ChairElectronically doped metal oxide nanocrystals exhibit tunable infrared localized surface plasmon resonances (LSPRs). Semiconductors provide an alternative dielectric environment than metallically bonded solids, such as noble metals, for metallic behavior. The ways in which the electronic structure of the semiconductor and of the dopants used to make them metallic hybridize substantially changes the plasmonic behavior. Choice of dopant element, dopant placement within the nanocrystal, and dopant interaction with other defects in the lattice all lead to changes in the observed optical properties of these nanocrystals. Here, the methods for optical characterization of LSPRs in doped metal oxides are discussed with particular attention directed at how undetermined heterogeneous contributions to ensemble measurements lead to misattributing inhomogenous broadening to poor plasmonic performance. Electronic damping in these materials is incredibly low compared to coinage metals, and they tout the added benefit of spectral tuning through chemical composition rather than morphology. The result is a class of materials that can both have their optical response tuned separately from other application relevant factors like nanocrystal size, and yield high performance LSPR for directing far-field radiation to the near-field. Learning that doped metal oxides have high quality factor LSPR was found through the first single nanocrystal measurements of LSPR made in the mid-IR through the use of near-field optics to interrogate these nanocrystals separately. The result was uncovering substantial nanocrystal-to-nanocrystal variation within batches of nanocrystals making ensemble measurements appear to have broad LSPR, while in fact t

La nanotecnología es la disciplina que se dedica al estudio y control de los fenómenos y materiales cuyo tamaño en al menos una de sus dimensiones es menor de 100 nm. Se cumple además que estos materiales suelen mostrar comportamientos de carácter cuántico debido a las reducidas dimensiones. Hay una gran cantidad de materiales cuyas propiedades cambian sustancialmente cuando su tamaño se ve reducido a escala nanométrica. Los nanomateriales y nanoestructuras resultantes al disminuir el tamaño de los materiales a escala nanométrica pueden alterar también las propiedades de un material masivo cuando se insertan o depositan sobre él. Las aplicaciones que se derivan de estas cualidades son innumerables y mayor aún el potencial que guarda para los años venideros. En este trabajo de tesis doctoral nos fijamos de forma particular en un fenómeno que ocurre a nanoescala, la resonancia plasmónica de superficie localizada. Esta resonancia aparece de forma deslocalizada en la interfaz de dos materiales, pero cuando uno de ellos tiene escala nanométrica, esta resonancia plasmónica de superficie aparece localizada en la nanoestructura. Esto permite confinar la luz en dimensiones menores que la propia longitud de onda de la luz. El objetivo principal de esta tesis doctoral es la creación de conocimiento para la mejora de las propiedades de materiales basados en nanoestructuras metálicas con propiedades plasmónicas. Este objetivo se persigue mediante el uso de técnicas basadas en la microscopía electrónica de transmisión, tanto estructurales como espectroscópicas. Dos de las técnicas de microscopía electrónica de transmisión más versátiles para el análisis de propiedades plasmónicas son la espectroscopia electrónica de pérdida de energía (EELS) sobre todo en la zona de bajas pérdidas (low-loss) y la microscopía electrónica de transmisión con filtrado de energía (EFTEM). En esta tesis se ha trabajado con ambas con el objetivo de estudiar la resonancia plasmónica de superficie localiz

La nanotecnología es la disciplina que se dedica al estudio y control de los fenómenos y materiales cuyo tamaño en al menos una de sus dimensiones es menor de 100 nm. Se cumple además que estos materiales suelen mostrar comportamientos de carácter cuántico debido a las reducidas dimensiones. Hay una gran cantidad de materiales cuyas propiedades cambian sustancialmente cuando su tamaño se ve reducido a escala nanométrica. Los nanomateriales y nanoestructuras resultantes al disminuir el tamaño de los materiales a escala nanométrica pueden alterar también las propiedades de un material masivo cuando se insertan o depositan sobre él. Las aplicaciones que se derivan de estas cualidades son innumerables y mayor aún el potencial que guarda para los años venideros. En este trabajo de tesis doctoral nos fijamos de forma particular en un fenómeno que ocurre a nanoescala, la resonancia plasmónica de superficie localizada. Esta resonancia aparece de forma deslocalizada en la interfaz de dos materiales, pero cuando uno de ellos tiene escala nanométrica, esta resonancia plasmónica de superficie aparece localizada en la nanoestructura. Esto permite confinar la luz en dimensiones menores que la propia longitud de onda de la luz. El objetivo principal de esta tesis doctoral es la creación de conocimiento para la mejora de las propiedades de materiales basados en nanoestructuras metálicas con propiedades plasmónicas. Este objetivo se persigue mediante el uso de técnicas basadas en la microscopía electrónica de transmisión, tanto estructurales como espectroscópicas. Dos de las técnicas de microscopía electrónica de transmisión más versátiles para el análisis de propiedades plasmónicas son la espectroscopia electrónica de pérdida de energía (EELS) sobre todo en la zona de bajas pérdidas (low-loss) y la microscopía electrónica de transmisión con filtrado de energía (EFTEM). En esta tesis se ha trabajado con ambas con el objetivo de estudiar la resonancia plasmónica de superficie localiz

When exposed to light, metal nanoparticles exhibit a phenomenon known as LSPR, Localized Surface Plasmon Resonance. The wavelengths at which LSPR occurs is very dependent on the refractive index of the surrounding medium. Binding of biomolecules to the surface of gold nanoparticles result in a change in the refractive index that can be detected spectrophotometrically by monitoring the LSPR peak shift. When functionalized with the corresponding ligand(s), gold nanoparticles can be utilized in biosensors to detect the presence and concentration of a predetermined analyte. However, the system must exhibit high specificity and give rise to a detectable shift for analytes in the desired concentration range to be of commercial interest. The aim of the diploma project was to investigate and optimize the biofunctionalization and performance of a fiber optics based LSPR biosensor. Three ligand systems were investigated for detection of antibodies (IgG), insulin and avidin. Binding of the analyte to the ligand caused a shift of a few nanometers when using spherical gold nanoparticles. The shifts were significantly larger when using gold nanorods. When using the IgG and insulin ligands, only minor unspecific binding was observed. The setup thus shows great potential for use in a wide range of sensing applications.

In this work, it is proposed a novel and cost-effective fabrication method for forming gold nanoparticle films on transparent substrates. The method involves fabrication of templated aluminium substrate by porous-type anodic oxidation of aluminium foils. Furthermore, a thin gold layer is deposited over and subsequently annealed which results into the gold nanoparticles formation. Additionally, it is proposed a transfer onto transparent substrates such as PDMS or PMMA. The goal of this research is to build a localized surface plasmon resonance (LSPR) sensor element with a high performance and low fabrication costs.

In this work, it is proposed a novel and cost-effective fabrication method for forming gold nanoparticle films on transparent substrates. The method involves fabrication of templated aluminium substrate by porous-type anodic oxidation of aluminium foils. Furthermore, a thin gold layer is deposited over and subsequently annealed which results into the gold nanoparticles formation. Additionally, it is proposed a transfer onto transparent substrates such as PDMS or PMMA. The goal of this research is to build a localized surface plasmon resonance (LSPR) sensor element with a high performance and low fabrication costs.

In this work, it is proposed a novel and cost-effective fabrication method for forming gold nanoparticle films on transparent substrates. The method involves fabrication of templated aluminium substrate by porous-type anodic oxidation of aluminium foils. Furthermore, a thin gold layer is deposited over and subsequently annealed which results into the gold nanoparticles formation. Additionally, it is proposed a transfer onto transparent substrates such as PDMS or PMMA. The goal of this research is to build a localized surface plasmon resonance (LSPR) sensor element with a high performance and low fabrication costs.

In this work, it is proposed a novel and cost-effective fabrication method for forming gold nanoparticle films on transparent substrates. The method involves fabrication of templated aluminium substrate by porous-type anodic oxidation of aluminium foils. Furthermore, a thin gold layer is deposited over and subsequently annealed which results into the gold nanoparticles formation. Additionally, it is proposed a transfer onto transparent substrates such as PDMS or PMMA. The goal of this research is to build a localized surface plasmon resonance (LSPR) sensor element with a high performance and low fabrication costs.

In this work, it is proposed a novel and cost-effective fabrication method for forming gold nanoparticle films on transparent substrates. The method involves fabrication of templated aluminium substrate by porous-type anodic oxidation of aluminium foils. Furthermore, a thin gold layer is deposited over and subsequently annealed which results into the gold nanoparticles formation. Additionally, it is proposed a transfer onto transparent substrates such as PDMS or PMMA. The goal of this research is to build a localized surface plasmon resonance (LSPR) sensor element with a high performance and low fabrication costs.

In this work, it is proposed a novel and cost-effective fabrication method for forming gold nanoparticle films on transparent substrates. The method involves fabrication of templated aluminium substrate by porous-type anodic oxidation of aluminium foils. Furthermore, a thin gold layer is deposited over and subsequently annealed which results into the gold nanoparticles formation. Additionally, it is proposed a transfer onto transparent substrates such as PDMS or PMMA. The goal of this research is to build a localized surface plasmon resonance (LSPR) sensor element with a high performance and low fabrication costs.

When exposed to light, metal nanoparticles exhibit a phenomenon known as LSPR, Localized Surface Plasmon Resonance. The wavelengths at which LSPR occurs is very dependent on the refractive index of the surrounding medium. Binding of biomolecules to the surface of gold nanoparticles result in a change in the refractive index that can be detected spectrophotometrically by monitoring the LSPR peak shift. When functionalized with the corresponding ligand(s), gold nanoparticles can be utilized in biosensors to detect the presence and concentration of a predetermined analyte. However, the system must exhibit high specificity and give rise to a detectable shift for analytes in the desired concentration range to be of commercial interest. The aim of the diploma project was to investigate and optimize the biofunctionalization and performance of a fiber optics based LSPR biosensor. Three ligand systems were investigated for detection of antibodies (IgG), insulin and avidin. Binding of the analyte to the ligand caused a shift of a few nanometers when using spherical gold nanoparticles. The shifts were significantly larger when using gold nanorods. When using the IgG and insulin ligands, only minor unspecific binding was observed. The setup thus shows great potential for use in a wide range of sensing applications.

In this work the adsorption of the antibiotic rifampicin (RP) on the surface of gold (AuNP) or silver nanoparticles (AgNP) was investigated using both surface-enhanced Raman scattering (SERS) and surface-enhanced resonance Raman scattering (SERRS) spectroscopies. Such spectra were obtained in the absence and presence of the surface modifier 2-mercaptoethanol (ME) using excitations by laser radiations of 532, 632.8 and 1064 nm wavelengths. The use of different conditions under the presence of ME led to changes in the spectral pattern ascribed to the influence of resonance Raman (RR) effect and distinct chemical interactions of RP with the metallic surfaces. The sensibility of the chromophoric moiety, i.e. a -conjugated orbital, to the adsorption geometries, which can be controlled by surface modifiers, impacts the RR effect. Theoretical models involving RP and metal atoms were obtained from Density Functional Theory (DFT) calculations, and used for supporting the vibrational assignment. © 2016 Elsevier B.V. All rights reserved.

Gold nanorods (NRs) with tunable plasmon-resonant absorption in the near-infrared region have considerable advantages over organic fluorophores as imaging agents due to their brightness and lack of photobleaching. However, the luminescence spectral properties of NRs have not been fully characterized at the single particle level due to lack of proper analytic tools. Here, we present a spectral phasor analysis method that allows investigations of NRs' spectra at single particle level showing the spectral variance and providing spatial information during imaging. The broad phasor distribution obtained by the spectral phasor analysis indicates that spectra of NRs are different from particle to particle. NRs with different spectra can be identified in images with high spectral resolution. The spectral behaviors of NRs under different imaging conditions, for example, different excitation powers and wavelengths, were revealed by our laser-scanning multiphoton microscope using a high-resolution spectrograph with imaging capability. Our results prove that the spectral phasor method is an easy and efficient tool in hyper-spectral imaging analysis to unravel subtle changes of the emission spectrum. We applied this method to study the spectral dynamics of NRs during direct optical trapping and by optothermal trapping. Interestingly, different spectral shifts were observed in both trapping phenomena.

Gold nanorods (NRs) with tunable plasmon-resonant absorption in the near-infrared region have considerable advantages over organic fluorophores as imaging agents due to their brightness and lack of photobleaching. However, the luminescence spectral properties of NRs have not been fully characterized at the single particle level due to lack of proper analytic tools. Here, we present a spectral phasor analysis method that allows investigations of NRs' spectra at single particle level showing the spectral variance and providing spatial information during imaging. The broad phasor distribution obtained by the spectral phasor analysis indicates that spectra of NRs are different from particle to particle. NRs with different spectra can be identified in images with high spectral resolution. The spectral behaviors of NRs under different imaging conditions, for example, different excitation powers and wavelengths, were revealed by our laser-scanning multiphoton microscope using a high-resolution spectrograph with imaging capability. Our results prove that the spectral phasor method is an easy and efficient tool in hyper-spectral imaging analysis to unravel subtle changes of the emission spectrum. We applied this method to study the spectral dynamics of NRs during direct optical trapping and by optothermal trapping. Interestingly, different spectral shifts were observed in both trapping phenomena.

A dual-resonance surface-enhanced Raman scattering (SERS) chip which also serves as a localized surface plasmon resonance (LSPR) refractive index sensor is proposed. The dual-resonance SERS chip can simultaneously enhance excitation and Stokes lines for Raman signals detection in a broad wavelength region with virtually no limitation. Thus, it is especially useful for Raman detection at long wave numbers and hyper Raman. The great performance of this chip relies on the highly independent tunability of the two localized plasmonic resonances from the optical to the nearinfrared region and the strict "hot spot" match in space for both resonant wavelengths. Furthermore, Raman signals of polymethyl-methacrylate (PMMA) from 500 cm(-1) to 3300 cm(-1) are measured in the experiments and an obvious superiority can be seen compared to a single-resonance SERS chip. In an addition, by using the subradiant magnetic dipole resonance, the LSPR refractive sensor gives a high sensitivity of 577 nm/RIU and high figure of merit (FoM) of 14.2. The experimental results are consistent with the simulated results. This dual-functional sensing chip opens a route for dual-modality detection of the concentration of some specific molecules., QC 20140818

Highly bounding light at metal surface by localized surface plasmon resonance (LSPR) improves the optical trapping of nanoparticles, which is called plasmonic trapping. Since LSPR is high related to the geometry of metal structures, the construction of metal nanostructure is extremely significant in the nano-trapping. In this work, the plasmonic trapping of dielectric nanoparticles in periodic gold polygon tetramers is investigated through finite-difference time-domain (FDTD) method. The simulation results of electric field distribution and the corresponding optical force indicate the number of side is quite important to the trapping efficiency that the square tetramers is obviously superior to other ones with more sides. However, this efficiency difference is also related to the size of nanoparticle that it is more sensitive to the smaller nanoparticles. Furthermore, the results also figure out not only trapping efficiency but also the trapping position is greatly influenced by the wavelength of trapping light in the same gold polygon tetramers. All our results open a way to selectively trap nanoparticles with required size at appointed positions, which has extensive application prospects in manipulation of nanoparticles in solution.

Highly bounding light at metal surface by localized surface plasmon resonance (LSPR) improves the optical trapping of nanoparticles, which is called plasmonic trapping. Since LSPR is high related to the geometry of metal structures, the construction of metal nanostructure is extremely significant in the nano-trapping. In this work, the plasmonic trapping of dielectric nanoparticles in periodic gold polygon tetramers is investigated through finite-difference time-domain (FDTD) method. The simulation results of electric field distribution and the corresponding optical force indicate the number of side is quite important to the trapping efficiency that the square tetramers is obviously superior to other ones with more sides. However, this efficiency difference is also related to the size of nanoparticle that it is more sensitive to the smaller nanoparticles. Furthermore, the results also figure out not only trapping efficiency but also the trapping position is greatly influenced by the wavelength of trapping light in the same gold polygon tetramers. All our results open a way to selectively trap nanoparticles with required size at appointed positions, which has extensive application prospects in manipulation of nanoparticles in solution.

Highly bounding light at metal surface by localized surface plasmon resonance (LSPR) improves the optical trapping of nanoparticles, which is called plasmonic trapping. Since LSPR is high related to the geometry of metal structures, the construction of metal nanostructure is extremely significant in the nano-trapping. In this work, the plasmonic trapping of dielectric nanoparticles in periodic gold polygon tetramers is investigated through finite-difference time-domain (FDTD) method. The simulation results of electric field distribution and the corresponding optical force indicate the number of side is quite important to the trapping efficiency that the square tetramers is obviously superior to other ones with more sides. However, this efficiency difference is also related to the size of nanoparticle that it is more sensitive to the smaller nanoparticles. Furthermore, the results also figure out not only trapping efficiency but also the trapping position is greatly influenced by the wavelength of trapping light in the same gold polygon tetramers. All our results open a way to selectively trap nanoparticles with required size at appointed positions, which has extensive application prospects in manipulation of nanoparticles in solution.

When an Au nanoparticle in a liquid medium is illuminated with resonant light of sufficient intensity, a nanometer scale envelope of vapor - a "nanobubble" - surrounding the particle, is formed. This is the nanoscale onset of the well-known process of liquid boiling, occurring at a single nanoparticle nucleation site, resulting from the photothermal response of the nanoparticle. Here we examine bubble formation at an individual metallic nanoparticle in detail. Incipient nanobubble formation is observed by monitoring the plasmon resonance shift of an individual, illuminated Au nanoparticle, when its local environment changes from liquid to vapor. The temperature on the nanoparticle surface is monitored during this process, where a dramatic temperature jump is observed as the nanoscale vapor layer thermally decouples the nanoparticle from the surrounding liquid. By increasing the intensity of the incident light or decreasing the interparticle separation, we observe the formation of micrometer-sized bubbles resulting from the coalescence of nanoparticle-"bound" vapor envelopes. These studies provide the first direct and quantitative analysis of the evolution of light-induced steam generation by nanoparticles from the nanoscale to the macroscale, a process that is of fundamental interest for a growing number of applications. © 2013 American Chemical Society.

Titanium nitride is considered a promising alternative plasmonic material and is known to exhibit localized surface plasmon resonances within the near-infrared biological transparency window. Here, local heating efficiencies of disk-shaped nanoparticles made of titanium nitride and gold are compared in the visible and near-infrared regions numerically and experimentally with samples fabricated using e-beam lithography. Results show that plasmonic titanium nitride nanodisks are efficient local heat sources and outperform gold nanodisks in the biological transparency window, dispensing the need for complex particle geometries.

When an Au nanoparticle in a liquid medium is illuminated with resonant light of sufficient intensity, a nanometer scale envelope of vapor - a "nanobubble" - surrounding the particle, is formed. This is the nanoscale onset of the well-known process of liquid boiling, occurring at a single nanoparticle nucleation site, resulting from the photothermal response of the nanoparticle. Here we examine bubble formation at an individual metallic nanoparticle in detail. Incipient nanobubble formation is observed by monitoring the plasmon resonance shift of an individual, illuminated Au nanoparticle, when its local environment changes from liquid to vapor. The temperature on the nanoparticle surface is monitored during this process, where a dramatic temperature jump is observed as the nanoscale vapor layer thermally decouples the nanoparticle from the surrounding liquid. By increasing the intensity of the incident light or decreasing the interparticle separation, we observe the formation of micrometer-sized bubbles resulting from the coalescence of nanoparticle-"bound" vapor envelopes. These studies provide the first direct and quantitative analysis of the evolution of light-induced steam generation by nanoparticles from the nanoscale to the macroscale, a process that is of fundamental interest for a growing number of applications. © 2013 American Chemical Society.

Titanium nitride is considered a promising alternative plasmonic material and is known to exhibit localized surface plasmon resonances within the near-infrared biological transparency window. Here, local heating efficiencies of disk-shaped nanoparticles made of titanium nitride and gold are compared in the visible and near-infrared regions numerically and experimentally with samples fabricated using e-beam lithography. Results show that plasmonic titanium nitride nanodisks are efficient local heat sources and outperform gold nanodisks in the biological transparency window, dispensing the need for complex particle geometries.

The possibility to enhance the local refractive index sensitivity using plasmonic coupling between spherical gold nanoparticles (Au-NPs) has been investigated. A strong and distinct optical coupling between Au-NPs of various sizes was achieved by controlling the interparticle separation using a layer-by-layer assembly of polyelectrolytes. The frequency of the coupled plasmon peak could be tuned by varying either the particle size or the interparticle separation, shown both experimentally and by theoretical simulations. The bulk refractive index (RI) sensitivity for the plasmonic coupling modes was investigated and compared to the RI sensitivity of monolayers of well-separated Au-NPs, and the results clearly demonstrates that the RI sensitivity can be significantly enhanced in plasmonically coupled Au-NPs. The proposed approach is simple and scalable and improves the rather modest RI sensitivity of spherical gold nanoparticles with a factor of 3, providing a new route for fabrication of inexpensive sensors based on plasmonic nanostructures.

Localized surface plasmon resonance (LSPR) biosensors are employed to detect target biomolecules which have particular resonance wavelengths. Accordingly, tunability of the LSPR wavelength is essential in designing LSPR devices. LSPR devices employing silver nano-particles present better efficiencies than those using other noble metals such as gold; however, silver nano-particles are easily oxidized when they come in contact with liquids, which is inevitable in biosensing applications. To attain both durability and tunabilty in a LSPR biosensor, this paper proposes alumina (AL2O3) capped silver nano-disks. It is shown that through controlling the thickness of the cap, the LSPR resonance frequency can be finely tuned over a wide range; and moreover, the cap protects silver nano-particles from oxidation and high temperature.