Browsing by Subject "Gold nanoparticles"

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Aggregation and deposition of gold nanoparticles in singular and binary particle systems : role of size, shape, and environmental characteristics
(2015-05) Afrooz, A. R. M. Nabiul; Saleh, Navid B.; Lawler, Desmond F; Liljestrand , Howard M; Kirisits, Mary J; Korgel, Brian A
Engineered nanomaterials (ENMs) are used in numerous applications due to their unique advantages. Gold nanomaterials (AuNMs) are one such functional ENM, which are utilized as model nanoparticles due to their controlled properties. AuNMs can be synthesized with highly uniform size and shape, where increase in the anisotropy gives rise to novel properties; e.g., unique Plasmon resonance, shape dependent physico-chemical properties, and quantum confinement, etc. These advantages have popularized the use of AuNMs in a wide range of applications in sensing, drug delivery, and photodynamic therapies. Increased use of these ENMs calls for systematic evaluation of the AuNMs to assess the effect of their size and shape on fate and transport in aquatic environment. The natural environment, due to the presence of natural colloids and potential presence of secondary ENMs, presents additional system complexities in studying ENM fate and transport. This dissertation was designed to address two major data gaps: i.e., roles of i) anisotropy and ii) presence of secondary particles on aggregation and deposition of AuNMs. Poly-acrylic acid (PAA) coated uniform-sized gold nanospheres (AuNS) and nanorods (AuNR) are utilized as model nanoparticles. The first part of this research investigated the effect of shape of AuNMs on their aggregation and deposition in singular particulate system under relevant ionic strengths. The second part of this dissertation focused on investigation of the effects of a secondary nanoparticle, i.e., pluronic acid modified single-walled carbon nanotubes (PA-SWNTs), on aggregation and filtration of AuNSs under a wide range of ionic strength. Effects of shape of AuNMs on their aggregation kinetics were investigated by employing time resolved dynamic light scattering (TRDLS) in a wide range of mono- and di-valent electrolyte conditions. Aggregation histories were obtained for the AuNSs and AuNRs in presence of a wide range of NaCl and CaCl2 conditions. The critical coagulation concentrations (CCCs), computed from the stability plots of the AuNMs, were used to compare the aggregation propensity of the PAA coated AuNSs with the AuNRs. The deposition kinetics was monitored using the quartz crystal microbalance with dissipation (QCM-D) technique for a range of NaCl concentrations. Deposition rates determined were used to understand the effects of shape of the AuNMs on their deposition kinetics. Experimental findings suggest that the shape of nanomaterials can influence interfacial properties and result in unique aggregation and deposition behavior under typical aquatic conditions Effects of AuNS size on their aggregation behavior was investigated using citrate stabilized 30 nm and 60 nm sized National Institute of Standards and Technology (NIST) standard particles in biological media. Continuous size evolution of AuNS aggregates was monitored over a 24 h period employing DLS and static light scattering (SLS). Electrokinetic measurements, UV-vis spectroscopy, and electron microscopy were performed for material characterization. The findings from this study indicate that initial differences in AuNS sizes diminish over time as the particles aggregate under the influence of elevated ionic strength in the media. The results from this study will likely influence characterization and experimental design considerations for in vitro nanotoxicity studies. The effects of the presence of a secondary particle, PA-SWNTs, on hetero-aggregation behavior of PAA coated AuNS were systematically studied over a wide range of mono- and divalent electrolyte conditions. PA modification of SWNTs made them stable in the entire range of electrolyte concentration where SWNT-SWNT aggregation has been eliminated via steric interaction. Hetero-aggregation mechanisms of AuNS were deciphered utilizing electron microscopy and electrokinetics. Experimental results suggest that the AuNS aggregates faster in hetero-dispersion in presence of PA-SWNT than in homo-disperstion at elevated ionic strength. However, hetero-rates are slower in case of low ionic strength cases. Techniques developed in this study can be can be adopted elsewhere to assess hetero-aggregation of a wider set of ENMs, hence achieving reliability in nanoparticle environmental exposure and risk. Co-transport of AuNS in presence of PA-SWNTs through saturated porous media was also assessed using bench-scale column experiments under a wide range of aquatic conditions (1-100 mM NaCl). Homogenous AuNS suspensions were utilized as control to compare their breakthrough properties with those of the AuNS hetero-dispersions (in presence of PA-SWNTs). This study also assessed the role of pre-coating of the collectors (with PA-SWNTs) on AuNS' mobility to understand the order of introduction of the secondary particles. The study results demonstrate that the presence of secondary particles and the order in which these are introduced to the experimental system strongly influence AuNS mobility. Thus ENM can be highly mobile or can get strongly filtered out, depending on the secondary PA-SWNT and background environmental conditions. This research not only evaluates the role of material attributes in their fate and transport but also extends to assess the role of environmental complexities on the same. The research findings enhance our current understanding of environmental interaction of the ENMs and call for further studies, incorporating additional complexities (i.e., material and system), to assess the fate, transport, and effects of the ENMs in the natural environment.
Characterization of atherosclerotic plaques using ultrasound guided intravascular photoacoustic imaging
(2011-05) Wang, Bo, 1981-; Emelianov, Stanislav Y.; Sokolov, Konstantin; Smalling, Richard; Litovsky, Silvio; Dunn, Andrew; Aglyamov, Salavat
Rupture of atherosclerotic plaque is closely related to plaque composition. Currently, plaque composition cannot be clinically characterized by any imaging modality. The objective of this dissertation is to use a recently developed imaging modality – ultrasound-guided intravascular photoacoustic (IVPA) imaging – to detect the distribution of two critical components in atherosclerotic plaques: lipid and phagocytically active macrophages. Under the guidance of intravascular ultrasound imaging, spectroscopic IVPA imaging is capable of detecting the spatially resolving optical absorption property inside a vessel wall. In this study, contrast in spectroscopic IVPA imaging was provided by either the endogenous optical property of lipid or optically absorbing contrast agent such as gold nanoparticles (Au NPs). Using a rabbit model of atherosclerosis, this dissertation demonstrated that ultrasound guided spectroscopic IVPA imaging could simultaneously image lipid deposits as well as macrophages labeled in vivo with Au NPs. Information of macrophage activity around lipid rich plaques may help to identify rupture-prone or vulnerable plaques. The results show that ultrasound guided IVPA imaging is promising for detecting plaque composition in vivo. Clinical use of ultrasound guided IVPA imaging may significantly improve the accuracy of diagnosis and lead to more effective treatments of atherosclerosis.
Development of a nanoprobe for tracking stem cell viability
(2019-09-12) Dhada, Kabir Singh; Suggs, Laura J.; Emelianov, Stanislav; Zoldan, Janeta; Tunnell, James; Ghosh, Debadyuti
Adult stem cell therapy has demonstrated improved outcomes for treating cardiovascular diseases in preclinical and clinical. The development of novel imaging tools may increase our understanding of the mechanisms of stem cell therapy, and a variety of imaging tools have been developed to image transplanted stem cells in vivo; however, they lack the ability to interrogate stem cell function longitudinally. The objective of this dissertation was to develop a nanoprobe capable of tracking stem cell viability in vivo using photoacoustic imaging. The nanoprobe consists of inert gold nanorods coated with a reactive oxygen species (ROS) sensitive near-infrared dye. Upon cell death, stem cells produce ROS to degrade the cell. Using this feature of stem cells, the viability can be measured by comparing the dye signal to the ROS insensitive gold nanorod signal, which can also be used to track stem cell location. Demonstrated in this dissertation is the design and development of this nanoprobe, followed by characterization of the nanoparticle, and subsequent studies tracking mesenchymal stem cell viability in vivo. The nanoprobe was successfully loaded into mesenchymal stem cells and was capable of tracking cell viability in vivo over a period of 10 days using photoacoustic imaging. In addition, the nanoprobe was applied toward measuring inflammation due to ischemia. The results of this work can provide insights on stem cell therapy mechanisms and may be used for enhancing and optimization of cell therapy in the future
Interactions of composite gold nanoparticles with cells and tissue : implications in clinical translation for cancer imaging and therapy
(2012-12) Tam, Justina Oichi; Sokolov, Konstantin V. (Associate professor)
Current methods to diagnose and treat cancer often involve expensive, time-consuming equipment and materials that may lead to unwanted side effects and may not even increase a patient’s chance of survival. Thus, for a while now, a large part of the research community has focused on developing improved methods to detect, diagnose, and treat cancer on the molecular scale. One of the most recently discovered methods of cancer therapy is targeted therapy. These targeted therapies have potential to provide a patient with a form of personalized medicine because these therapies are biological molecules that specifically target other molecules involved with a cancer’s growth. Past trials using these therapeutic molecules, however, have led to controversial results, where certain patients responded better than others to the therapy for unknown reasons. Elucidating the reason behind these mixed results can be accomplished using metal nanoparticle technologies which could provide a bright signal to monitor the path that these therapeutic molecules take in vivo as well as enhance the molecule’s efficacy. Literature has shown that presenting targeting molecules in a dense manner to their target will increase these molecules’ binding affinity. This concept has been explored here to increase binding affinity of therapeutic molecules by attaching these molecules in a dense manner on the surface of gold nanoparticles, and correlating this increased affinity with therapeutic efficacy. Additionally, gold nanoparticles provide an easy surface for molecules to be functionalized on and have shown to be effective imaging, x-ray, and photothermal therapy agents. A major roadblock to using these gold nanoparticles clinically is their non-degradability and thus potential to cause long-term negative side effects in vivo. A platform for developing biodegradable gold nanoparticles is also explored here to take advantage of the gold nanoparticles’ excellent imaging and drug delivery capabilities while still allowing them to be used safely in the long term.
Investigation of gold nanoparticle accumulation kinetics for effective cancer targeting
(2010-08) Park, Jaesook; Tunnell, James W.; Dunn, Andrew K.; Sokolov, Konstantin; Roy, Krishnendu; Krishnan, Sunil
Gold nanoparticles (GNP) have been widely used as optical imaging and photothermal therapy agents due to their biocompatibility, simplicity of conjugation chemistry, optical tunability and efficient light conversion to heat. A number of in vitro and in vivo studies have demonstrated that they can be used as effective thermal therapy and imaging contrast agents to treat and diagnose cancer. As clinical applications of GNPs for cancer imaging and therapy have gained interest, efforts for understanding their accumulation kinetics has become more important. Given the recent demonstration of intrinsic two-photon induced photoluminescence (TPIP) of gold nanoshells (GNSs) and gold nanorods (GNRs), TPIP imaging is an efficient tool for investigating the microscopic distribution of the GNPs at intra-organ level. The following work explores these GNPs’ physical and optical properties for effective use of GNPs in TPIP imaging and examines the feasibility of using intrinsic TPIP imaging to investigate GNP’s biodistribution in bulk tumors and thin tissue slices processed for standard histology. Our results showed that GNPs yield a strong TPIP signal, and we found that the direct luminescence-based contrast imaging of GNPs can image both GNPs and nuclei, cytoplasm or vasculature simultaneously. Also, we present the effect of GNP morphology on their distribution within organs. Collected images showed that GNPs had a heterogeneous distribution with higher accumulation at the tumor periphery. However, GNRs had deeper penetration into tumor than GNRs due to their shape and size. In addition, GNPs were observed in unique patterns close to vasculature. Finally, we introduce single- and multiple-dose administrations of GNPs as a way of increasing GNP accumulation in tumor. Our results show that multiple dosing can increase GNP accumulation in tumor 1.6 to 2 times more than single dosing. Histological analysis also demonstrated that there were no signs of acute toxicity in tumor, liver and spleen excised from the mice receiving 1 injection, 5 injections of GNPs and trehalose injection.
Metal nanoparticles for signal amplification in biosensors and signal suppression in fluorescence measurements
(2021-05-05) Kogan, Molly; Webb, Lauren J.; Elber, Ron; Baiz, Carlos R; Gordon, Vernita
Metal nanoparticles are particles made up of many individual metal atoms ranging in size from one nanometer to hundreds of nanometers in diameter. Originally these particles were used in glazes to make lustrous patterns on pottery. It was not until Michael Faraday’s discovery of colloidal gold in 1856 that nanoparticles were characterized. Since then, nanoparticles of different compositions, sizes, and shapes have been implemented in fields such as catalysis and biotechnology. This dissertation will address two applications of nanoparticles: silver nanoparticles (AgNPs) to amplify signal in a paper-based fluidic device and gold nanoparticles (AuNPs) to quench signal in studies of cell penetrating peptides (CPPs). First, the paper-based device used concentrates a “sandwich-type” immunoassay, made of a capture antibody bound to a magnetic microbead and a detection antibody bound to a AgNP label, at a screen-printed carbon electrode by a magnet. The AgNP labels are oxidized to Ag ions, reduced, and stripped off the electrode in a technique known as anodic stripping voltammetry. Originally, this device could only detect AgNP concentrations as low as 2.1 pM. Scanning electron microscopy (SEM) was used to investigate the percentage of AgNPs oxidized in this detection method enabling optimization of the electrochemical parameters for higher signal output. This lowered the detection limit to 2.6 fM, which is now at a sensitivity comparable to a commercial pregnancy test. Second, this dissertation focuses on the use of AuNPs to suppress signal in fluorescence studies of cell penetrating peptides (CPPs), a class of peptides so effective in crossing cellular membranes that they can be used to carry cargo such as proteins or small molecules into a cell. The mechanism by which CPPs can permeate cell membranes is poorly understood. Here we use a model system composed of phospholipid vesicles and small fluorescent peptides to investigate the transport and mechanism of these peptides interacting with the lipid bilayer. While fluorescence signal can reveal details such as the amount of peptide that transports inside the vesicles, it cannot determine the depth that a peptide penetrates through the vesicles. By growing AuNPs inside these vesicles, however, we can use fluorescence quenching to determine the proximity of the peptide to the center of the vesicles, which will be important as we continue to study CPPs and their permeation through cell membranes.
Molecular specific photoacoustic imaging using plasmonic gold nanoparticles
(2009-12) Mallidi, Srivalleesha; Emelianov, Stanislav Y.
Cancer has become one of the leading causes of death today. The early detection of cancer may lead to desired therapeutic management of cancer and to decrease the mortality rate through effective therapeutic strategies. Advances in materials science have enabled the use of nanoparticles for added contrast in various imaging techniques. More recently there has been much interest in the use of gold nanoparticles as optical contrast agents because of their strong absorption and scattering properties at visible and near-infrared wavelengths. Highly proliferative cancer cells overexpress molecular markers such as epidermal growth factor receptor (EGFR). When specifically targeted gold nanoparticles bind to EGFR they tend to cluster thus leading to an optical red-shift of the plasmon resonances and an increase in absorption in the red region. These changes in optical properties provide the foundation for photoacoustic imaging technique to differentiate cancer cells from surrounding benign cells. In photoacoustic imaging, contrast mechanism is based on the optical absorption properties of the tissue constituents. Studies were performed on tissue phantoms, ex-vivo and in-vivo tumor models to evaluate molecular specific photoacoustic imaging technique. The results indicate that highly sensitive and selective detection of cancer cells can be achieved by utilizing the plasmon resonance coupling effect of EGFR targeted gold nanoparticles and photoacoustic imaging. In conclusion, the combined ultrasound and photoacoustic imaging technique has the ability to image molecular signature of cancer using bioconjugated gold nanoparticles.
Nanocomposite particles as theranostic agents for cancer
(2012-08) Larson, Timothy Arne; Sokolov, Konstantin V. (Associate professor); Ellington, Andrew D.
The exploration of nanoparticles for applications in medicine has grown dramatically in recent years. Due to their size, nanoparticles provide an ideal platform for combining multiple functionalities and interfacing directly with the biological realm. Additionally, nanoparticles can have physical properties that don't naturally exist in biology. Metal nanoparticles in particular have unique optical and magnetic properties which have driven nanomaterials research. The optical properties of gold nanoparticles and the magnetic properties of iron nanoparticles make them suitable for use as contrast agents in diagnostics and for radiation enhancement in therapeutic applications. The strong optical absorption and scattering and the nature of the conduction electrons of gold particles makes them ideal contrast agents for two-photon microscopy, photoacoustic imaging, and photothermal therapy. The superparamagnetic nature of iron oxide nanoparticles is clearly visible in magnetic resonance imaging, rendering them suitable as whole-body imaging contrast agents. All nanoparticle types can serve as delivery vehicles for drugs consisting of small molecules, peptides, or nucleic acids. This multiplicity of characteristics renders nanoparticles suitable for use in combining diagnosis and therapy, such as using particles to first detect the spatial extent of a cancer, and then to enhance near-infrared radiation in the tissue optical window to induce localized heating of diseased tissue. This combined approach requires both a mechanism of enhanced imaging contrast and a localized therapeutic mechanism, and the studies presented in this dissertation present work both on these aspects. By coating iron oxide nanoparticle cores with gold shells, it is possible to obtain a nanoparticle with both magnetic and optical properties. While individual gold nanoparticles do not absorb light in the infrared, receptor-mediated aggregation and the plasmon coupling effect lead to enhanced optical absorption only in diseased tissue. In addition to exploring these advanced applications, this work presents a fundamental investigation into the stability of gold nanoparticles in biological media. A previously unknown mechanism of gold nanoparticle destabilization and opsonization is presented and supported, along with a technique for reducing this opsonization and greatly enhancing the stability of gold particles in biological applications. This work will provide guidance to future designs of nanoparticle systems.
Nanoparticle-mediated photothermal therapy of tumors : a comparative study of heating efficiencies for different particle types
(2010-05) Pattani, Varun Paresh; Tunnell, James W.; Ren, Pengyu
Cancer is one of the most notorious diseases affecting the human population today with very few effective treatments. Due to the disparate nature of cancers, it is difficult to obtain a treatment that can cure cancer. Thus, there is a large influx of research towards cancer therapies, leading to one of the discovery that cancer cells (tumors) have a low thermotolerance in comparison to normal cells. If the temperature of the cancer cells is increased into the hyperthermia range (~45°C) thermal damage occurs, causing cell death by protein denaturation and membrane disruption. A recent development in this field has been in the photothermal treatment of tumors, which is starting to utilize plasmonic particles to enhance the specificity of the treatment. The plasmonic nanoparticles, specifically gold, can reach the tumor site using passive targeting and when irradiated with a tuned laser will emit heat localized to a small region around the nanoparticle killing the surrounding cancer cells. This process has been shown to reduce tumor size in vivo with gold nanoshells and gold nanorods. However, it has not been shown which particle is better at delivering the heat to the tumor site. Therefore in this study, it will be shown which particle generates the most heat. Solutions of tissue simulating phantom and different concentrations of nanoparticles were irradiated with a laser to measure the increase in temperature. Additionally, simulations were performed using Mie Theory for nanoshells and the Discrete Dipole Approximation for nanorods. Based on the physical parameters of the nanoshells and nanorods used in this experiment, the adjusted absorption cross-section was determined. It was found that nanoshells generated the most amount of heat on a per particle basis, and that it was necessary to have a nanorod concentration of 5.5 times the concentration of nanoshells to generate the same amount of heat as nanoshells. These results were confirmed using Monte Carlo and Finite Difference Modeling of the nanoparticle heating experiments. However, the choice of nanoparticle still depends on the application and the targeting efficiency in vivo.
Near-infrared narrowband imaging of tumors using gold nanoparticles
(2011-12) Puvanakrishnan, Priyaveena; Tunnell, James W.
A significant challenge in the surgical resection of tumors is accurate identification of tumor margins. Current methods for margin detection are time-intensive and often result in incomplete tumor excision and recurrence of disease. The objective of this project was to develop a near-infrared narrowband imaging (NIR NBI) system to image tumor and its margins in real-time during surgery utilizing the contrast provided by gold nanoparticles (GNPs). NIR NBI images narrow wavelength bands to enhance contrast from plasmonic particles in a widefield, portable and non-contact device that is clinically compatible for real-time tumor margin demarcation. GNPs have recently gained significant traction as nanovectors for combined imaging and photothermal therapy of tumors. Delivered systemically, GNPs preferentially accumulate at the tumor site via the enhanced permeability and retention effect, and when irradiated with NIR light, produce sufficient heat to treat tumor tissue. The NIR NBI system consists of 1) two LED's: green (530 nm) and NIR (780 nm) LED for illuminating the blood vessels and GNP, respectively, 2) a filter wheel for wavelength selection, and 3) a CCD to collect reflected light from the sample. The NIR NBI system acquires and processes images at a rate of at least 6 frames per second. We have developed custom control software with a graphical user interface that handles both image acquisition and processing/display in real-time. We used mice with a subcutaneous tumor xenograft model that received intravenous administration and topical administration of gold nanoshells and gold nanorods. We determined the GNP's distribution and accumulation pattern within tumors using NIR NBI. Ex vivo NIR NBI of tumor xenografts accumulated with GNPs delivered systemically, demonstrated a highly heterogeneous distribution of GNP within the tumor with higher accumulation at the cortex. GNPs were observed in unique patterns surrounding the perivascular region. The GNPs clearly defined the tumor while surrounding normal tissue did not indicate the presence of particles. In addition, we present results from NBI of tumors that received topical delivery of conjugated GNPs. We determined that tumor labeling using topical delivery approach resulted in a more homogenous distribution of GNPs compared to the systemic delivery approach. Finally, we present results from the on-going in vivo tumor margin imaging studies using NIR NBI. Our results demonstrate the feasibility of NIR NBI in demarcating tumor margins during surgical resection and potentially guiding photo-thermal ablation of tumors.
Near-IR plasmonic contrast agents for molecular imaging, cell tracking and clinical translation
(2014-05) Joshi, Pratixa Paritosh; Sokolov, Konstantin V. (Associate professor)
Gold nanoparticles attain an intense focus in biomedical imaging applications due to their unique optical properties, facile conjugation with biomolecules, and biocompatibility. Although a considerable amount of work towards the development of gold nanoparticles has been completed, these promising contrast agents have not yet reached the clinic due to several challenges including efficient accumulation at the diseased site, sensitivity of detection in vivo, potential adverse effects, and clearance from the body. High signal-to-background ratio is required to enhance sensitivity of detection. Because near infrared (near-IR) light has the best tissue penetration, contrast agents designed to work in this range can significantly increase imaging sensitivity. Moreover, efficient targeting of the molecular biomarkers on diseased cells can decrease the required dosage, increase the site-specific accumulation, and enhance the imaging sensitivity. Molecular-specific contrast agents developed in this project use directional attachment of antibody molecules to the nanoparticle surface, enhancing the targeting efficacy. Additionally, cell-based delivery of diagnostic and therapeutic agents is gaining much interest due to the immune cells’ special access to the avascular, diseased regions. The contrast agents developed in this project enable detection of just a few cells per unit of imaging volume, enable multiplex imaging, and open up a possibility for tracking different cell populations with noninvasive photoacoustic and ultrasound imaging. Finally, the clearance of nanoparticles from the body dictates their clinical translation. The in vivo pharmacokinetics study along with the proposed in vitro model explored in this project will enable fast, reliable, and cost-efficient screening of promising agents and facilitate quick optimization of nanoparticles for their potential use in the clinic.
Progress towards visualizing the controlled assembly of gold nanoparticles on DNA
(2011-05) Elmuccio, Michael L.; Iverson, Brent L.; Anslyn, Eric
Our laboratory has used the 1,4,5,8 Naphthalenetetracarboxylic diimine (NDI) unit to develop threading polyintercalators that bind DNA with the NDI units intercalated in between GpG steps and two different peptide linkers, which connect the NDI units, situated in either the major or minor grooves. The first generation bisintercalators, G₃K and [beta]Ala₃K, were shown to bind two different sequences of DNA, where the peptide linkers reside in the major and minor grooves respectively. These binding modules were then combined to generate threading polyintercalators that bound different DNA sequences with simultaneous occupation of both grooves. In particular, a cyclic bisintercalator was designed and DNAse I footprinting revealed a strong preference for the sequence 5'-GGTACC-3'. NMR structural studies of the complex with d(CGGTACCG)₂ verified a pseudocatenane structure in which the NDI units reside four base pairs apart, with one linker located in the minor groove and the other in the major groove. This was the first structurally well-characterized pseudocatenane complex between a sequence-specific cyclic bisintercalator and its preferred binding sequence. The ability to simultaneously occupy both groves of the same sequence is interesting for several reasons. Most significantly, it raises questions about a complex DNA intercalator's ability to locate its preferred sequence within a long strand of DNA. In order to directly assess this, the intercalator was modified (CBI-Cys) to incorporate a gold nanoparticle probe to allow for the direct visualization of the intercalator locating its preferred sequence within a long DNA strand. The appropriate protocols to visualize DNA using electron and atomic force microscopy were unsuccessful; however, the foundation has been set for future work to develop the appropriate method to determine the mechanism by which the cyclic bisintercalator locates its preferred sequence. Additionally, the bisintercalators developed in our laboratory offered a unique opportunity to exploit their sequence specificity for controlled nanoparticle assembly. Over the past decade, nanoparticles and DNA have been used to develop novel nanoparticle assembly systems with the goal of developing electronic devices and nanomaterials. The G₃K bisintercalator was synthetically modified to incorporate a gold nanoparticle probe. This intercalator-nanoparticle conjugate, BisKC·Au, maintained its binding specificity (5'-GGTACC-3') to a modified DNA fragment containing multiple G₃K binding sites. The atomic force microscope has become the most promising tool in visualizing individual DNA molecules. A modified procedure utilized APS to allow for the direct visualizing of plasmid DNA. The framework is now in place to confirm the controlled assembly of the gold nanoparticles. This protocol can then be used for the [beta]Ala₃K bisintercalator to lead to the development of a nanoparticle assembly system that can precisely control the organization of multiple types of nanoparticles.