Bimetallic Nanoparticles: Enhanced Magnetic and Optical Properties for Emerging Biological Applications (original) (raw)

Synthesis and Characterization of Various Bimetallic Nanoparticles and Their Application

Applied Nano

Bimetallic nanoparticles are a complex nanoscale combination of two metal constituents. The superior properties of bimetallic nanoparticles (BNPs) compared with monometallic nanoparticles have attracted much attention from both scientific and technological perspectives. In recent years, many fabrication techniques have been proposed, and the detailed characterization of bimetallic nanoparticles has been made possible by the rapid advancement of nanomaterial analysis techniques. Metallic nanoparticles can be classified according to their origin, size, and structure, and their synthesis process can be physical, chemical, or biological. Bimetallic nanoparticles are more attractive than metal nanoparticles due to their unique mixing patterns and synergistic effects of two metal nanoparticles forming the bimetal. In this review, the different bimetallic synthesis methods and various characterization techniques are discussed. The paper will also discuss various applications for bimetallic...

Cell Imaging with Fluorescent Bi-Metallic Nanoparticles

JOURNAL OF ADVANCES IN CHEMISTRY

Last decades various imaging techniques have been applied in biological and biomedical research, such as magnetic resonance imaging, different types of tomography, fluorescence/bioluminescence, ultrasound, as well as multimodality approaches. Fluorescence imaging, especially in combination with nanoscale materials, is a very prospective tool for experiments in vivo and clinical applications due to its high temporal and spatial resolutions. Fluorescent nanoparticles (NPs), having ability to interact with biomolecules both on the surface of and inside the cells, may revolutionize the cell imaging approaches for diagnostics and therapy. In our investigation we report about new method of cell imaging with fluorescent bi-metallic NPs synthesized by chemical reduction of the relevant ions. As the model of living organism, the cells of yeast Hansenula polymorpha were used. All NPs in minimal concentration (up to 0.05 mM) was proved to be non-toxic for yeast cells. The NPs and NPs-modified ...

Magnetic, fluorescent and hybrid nanoparticles: From synthesis to application in biosystems

Materials Science and Engineering: C, 2019

Multifunctional nanoparticles have emerged as an outstanding candidate for a new generation of biomedical applications, mainly due to their remarkable properties and biocompatibility. Individual reports on multi-metal, semiconducting and superparamagnetic nanoparticles (SPIONs), elucidating on each's unique intrinsic properties, have demonstrated that the biological application of such materials is highly dependent of their size, shape, surface nature and core nature. However, reviews combining nanoparticles with multiple properties, as fluorescence and paramagnetism, as well as, biocompatibility, toxicology and biodegradability are yet seldom. This review highlights the highest output advances, of the last decade, on synthetic procedures for the design of multifunctional magneto-luminescent hybrid nanosystems based on quantum dots, SPIONs and mesoporous silica nanoparticles, as well as, surface modifications and their role for biological applications. 1.1. Quantum dots Concerning fluorescent nanomaterials, quantum dots (QDs) comprised of inorganic elements of groups II-VI or III-V, are very promising, mainly due to their unique optical properties [36,45] that arise from the confinement of charge carriers' energy states through the physical size reduction of these nanoparticles. Briefly, a decrease in the size,

Feasibility of Using Bimetallic Plasmonic Nanostructures to Enhance the Intrinsic Emission of Biomolecules

The Journal of Physical Chemistry C, 2011

Detection of the intrinsic fluorescence from proteins is important in bio-assays because it can potentially eliminate the labeling of external fluorophores to proteins. This is advantageous because using external fluorescent labels to tag biomolecules requires chemical modification and additional incubation and washing steps which can potentially perturb the native functionality of the biomolecules. Hence the external labeling steps add expense and complexity to bio-assays. In this paper, we investigate for the first time the feasibility of using bimetallic nanostructures made of silver (Ag) and aluminum (Al) to implement the metal enhanced fluorescence (MEF) phenomenon for enhancing the intrinsic emission of biomolecules in the ultraviolet (UV) spectral region. Fluorescence intensities and lifetimes of a tryptophan analogue N-acetyl-Ltryptophanamide (NATA) and a tyrosine analogue N-acetyl-L-tyrosinamide (NATA-tyr) were measured. Increase in fluorescence intensities of upto 10-fold and concurrent decrease in lifetimes for the amino acids were recorded in the presence of the bimetallic nanostructures when compared to quartz controls. We performed a model protein assay involving biotinylated bovine serum albumin (bt-BSA) and streptavidin on the bimetallic nanostructured substrate to investigate the distance dependent effects on the extent of MEF from the bimetallic nanostructures and found a maximum enhancement of over 15-fold for two layers of bt-BSA and streptavidin. We also used finite difference time domain (FDTD) calculations to explore how bimetallic nanostructures interact with plane waves and excited state fluorophores in the UV region and demonstrate that the bimetallic substrates are an effective platform for enhancing the intrinsic emission of proteins and other biomolecules.

Composite magnetic–plasmonic nanoparticles for biomedicine: Manipulation and imaging

Nano Today, 2013

Iron oxide-gold nanoparticles that exhibit both magnetic and plasmonic behaviors have great potential for biomedical applications. The ability to remotely control the spatial position of a nanoparticle in real time while tracking its motion provides an exciting new tool for nanoscale sensing. In this review we summarize the major efforts in the design and synthesis of iron oxide-gold nanoparticles. The underlying magnetophoretic and plasmonic characteristics of gold and iron oxide nanoparticles that enable their use for biomedical applications are described. We discuss the challenges associated with the integration of iron oxide and gold in one unified nanostructure, including the chemical techniques involved in making such composite material. We emphasize on the importance of colloidal stability, and explain how this property determines the functionality of iron oxide-gold nanoparticles in physiological environment. Afterwards, we examine both the magnetophoresis and localized surface plasmon resonance of iron oxide-core gold-shell structure and provide theoretical explanations for these properties. Finally we suggest potential opportunities for use of iron oxide-gold nanoparticles.

Optical properties and biomedical applications of plasmonic nanoparticles

Journal of Quantitative Spectroscopy and Radiative Transfer, 2010

Nanoparticle plasmonics is a rapidly emerging research field that deals with the fabrication and optical characterization of noble metal nanoparticles of various size, shape, structure, and tunable plasmon resonances over VIS-NIR spectral band. The recent simultaneous advances in synthesis, characterization, electromagnetic simulation, and surface functionalization of plasmonic nanoparticles by biospecific molecular probes have led to a perfect publication storm in discoveries and potential biomedical applications of plasmon-resonant nanoparticle bioconjugates. Here, we present an overview of these topics. First, we discus basic wet-chemical routes to fabricate conjugates of gold, silver, or composite particles with controllable size, shape, structure and with surface functionalization by biospecific molecules. Second, we consider the single-particle dipole and multipole optics and coupled plasmonic nanoparticle arrays. Finally, we discus application of plasmonic bioconjugates to such fields as homogeneous and solid-phase assays, biomedical sensing and imaging, biodistribution and toxicity aspects, drug delivery and plasmonic photothermal therapy.

Synthesis, Functionalization, and Biomedical Applications of Multifunctional Magnetic Nanoparticles

Advanced Materials, 2010

magnetically, enabling some exciting new approaches to bioseparation, biodetection and targeted drug delivery. [ 6−10 ] In addition, these MNPs can also respond resonantly to an alternating magnetic fi eld and function as a heater, offering a promising therapeutic solution by magnetic fl uid hyperthermia. [ 11 , 12 ] To perform real-time monitoring and drug treatment with high accuracy, MNPs are often coupled with targeting agents, therapeutic drugs, and other functional probes. However, these multistep conjugations to a single-component NP are usually low yield processes and the presence of different molecules on the same NP surface may interfere with targeting capabilities and the subsequent uptake of the NP conjugates. Recent advances in NP research allow the synthesis of various composite NPs with core/shell and dumbbell structures that offer a promising solution to this problem encountered with single-component MNPs. For example, Au-Fe 3 O 4 dumbbell NPs were applied by conjugating anticancer drug cisplatin (cis-diamminedichloroplatinum) on Au and Herceptin (HER) antibodies on Fe 3 O 4 with the number of cisplatin molecules and antibody molecules being controlled by the size of the Au and Fe 3 O 4 components. [ 13 ] The composite NPs demonstrated the targeted specifi c delivery of cisplatin to breast tumor cells (SK-BR-3). Alternatively, by proper surface functionalization, FePt NPs were found to release Fe that was highly cytotoxic. [ 14 ] Utilized as a therapeutic agent, these NPs might offer a promising approach to the multistep conjugation problem in NP delivery systems, as one would only need to anchor a targeting agent on the NP surface and the number of targeting molecules could be readily controlled by NP size. This review summarizes recent progress in the design and fabrication of multifunctional MNPs (MFMNPs) for biomedical applications. It fi rst outlines the general synthesis of composite NPs of iron oxide, alloys, core/shell, dumbbell, and multicomponent adducts. It then discusses the chemistry applied for surface modifi cation to make these MFMNPs biocompatible. Finally, the review highlights the potential applications of these MFMNPs in multimodality imaging and target-specifi c drug/gene delivery. 2. Chemical Synthesis of MNPs The general strategy for preparing monodisperse NPs in solution phase is to separate the nucleation and growth of nanocrystals. Synthesis of multifunctional magnetic nanoparticles (MFMNPs) is one of the most active research areas in advanced materials. MFMNPs that have magnetic properties and other functionalities have been demonstrated to show great promise as multimodality imaging probes. Their multifunctional surfaces also allow rational conjugations of biological and drug molecules, making it possible to achieve target-specifi c diagnostics and therapeutics. This review fi rst outlines the synthesis of MNPs of metal oxides and alloys and then focuses on recent developments in the fabrication of MFMNPs of core/shell, dumbbell, and composite hybrid type. It also summarizes the general strategies applied for NP surface functionalization. The review further highlights some exciting examples of these MFMNPs for multimodality imaging and for target-specifi c drug/gene delivery applications.

Synthesis, physical properties, and biomedical applications of magnetic nanoparticles: a review

Progress in Biomaterials

Recent innovations in nanotechnology have opened the applicability of multifunctional nanoparticles (NPs) in biomedical diagnosis and treatment. The examples of NPs which have attracted considerable attention in recent years are metals (e.g., Au, Ag, Mg), alloys (e.g., Fe-Co, Fe-Pd, Fe-Pt, Co-Pt), iron oxides (e.g., Fe 2 O 3 and Fe 3 O 4), substituted ferrites (e.g., MnFe 2 O 4 and CoFe 2 O 4), manganites (e.g., La 0.67 Sr 0.33 MnO 3), etc. Special attention has been paid to magnetic NPs (MNPs), as they are the potential candidates for several biomedical appliances, such as hyperthermia applications, magnetic resonance imaging, contrast imaging, and drug delivery. To achieve effective MNPs, a thorough investigation on the synthesis, and characteristic properties, including size, magnetic properties, and toxicity, is required. Furthermore, the surfaces of the NPs must be tailored to improve the biocompatibility properties and reduce agglomeration. The present review focuses on different mechanisms to develop biocompatible MNPs. The utility of these MNPs in various biomedical applications, especially in treating and diagnosing human diseases, such as targeted drug delivery, hyperthermia treatment for cancer, and other biomedical diagnoses, is thoroughly discussed in this article. Different synthetic processes and important physical properties of these MNPs and their biocomposites are presented.

Review of Some Interesting Surface Plasmon Resonance-enhanced Properties of Noble Metal Nanoparticles and Their Applications to Biosystems

Plasmonics, 2007

Noble metal, especially gold (Au) and silver (Ag) nanoparticles exhibit unique and tunable optical properties on account of their surface plasmon resonance (SPR). In this review, we discuss the SPR-enhanced optical properties of noble metal nanoparticles, with an emphasis on the recent advances in the utility of these plasmonic properties in molecular-specific imaging and sensing, photo-diagnostics, and selective photothermal therapy. The strongly enhanced SPR scattering from Au nanoparticles makes them useful as bright optical tags for molecularspecific biological imaging and detection using simple dark-field optical microscopy. On the other hand, the SPR absorption of the nanoparticles has allowed their use in the selective laser photothermal therapy of cancer. We also discuss the sensitivity of the nanoparticle SPR frequency to the local medium dielectric constant, which has been successfully exploited for the optical sensing of chemical and biological analytes. Plasmon coupling between metal nanoparticle pairs is also discussed, which forms the basis for nanoparticle assembly-based biodiagnostics and the plasmon ruler for dynamic measurement of nanoscale distances in biological systems.