Challa S. S. R. Kumar

Microfluidic Synthesis of Nanomaterials

An overview of the current information and analyses on the microfluidic synthesis of different types of nanomaterial, including metallic and silica nanoparticles and quantum dots, is presented. Control of particle size, size distribution, and crystal structure of nanomaterials are examined in terms of the special features of microfluidic reactors.

Raman spectroscopy for nanomaterials characterization

This is a first volume of a 40-volume series on nanoscience and nanotechnology, edited by the renowned scientist Challa S.S.R. Kumar. This handbook gives a comprehensive overview about Raman spectroscopy for the characterization of nanomaterials. Modern applications and state-of-the-art techniques are covered and make this volume essential reading for research scientists in academia and industry.

Molecular MRI for sensitive and specific detection of lung metastases

Early and specific detection of metastatic cancer cells in the lung (the most common organ targeted by metastases) could significantly improve cancer treatment outcomes. However, the most widespread lung imaging methods use ionizing radiation and have low sensitivity and/or low specificity for cancer cells. Here we address this problem with an imaging method to detect submillimeter-sized metastases with molecular specificity. Cancer cells are targeted by iron oxide nanoparticles functionalized with cancer-binding ligands, then imaged by high-resolution hyperpolarized 3He MRI. We demonstrate in vivo detection of pulmonary micrometastates in mice injected with breast adenocarcinoma cells. The method not only holds promise for cancer imaging but more generally suggests a fundamentally unique approach to molecular imaging in the lungs.

Gold–silica quantum rattles for multimodal imaging and therapy

Significance Therapeutic and diagnostic nanoparticles combine multiple functionalities to improve efficacy of treatment but often require assembling complex systems at the expense of overall performance. Here we present a simple strategy to synthesize a hybrid, rattle-like, gold–silica nanoparticle that very efficiently combines therapy and imaging in an animal model. The nanoparticle design is uniquely centered on enabling the use of gold quantum dots (<2 nm) in biological systems. The resulting nanoparticles are highly biocompatible and display emergent photonic and magnetic properties matching and in some instances outperforming state-of-the-art nanotechnology-based medical agents for each of the functionalities investigated, promising a tighter integration between imaging and therapy. Gold quantum dots exhibit distinctive optical and magnetic behaviors compared with larger gold nanoparticles. However, their unfavorable interaction with living systems and lack of stability in aqueous solvents has so far prevented their adoption in biology and medicine. Here, a simple synthetic pathway integrates gold quantum dots within a mesoporous silica shell, alongside larger gold nanoparticles within the shell’s central cavity. This “quantum rattle” structure is stable in aqueous solutions, does not elicit cell toxicity, preserves the attractive near-infrared photonics and paramagnetism of gold quantum dots, and enhances the drug-carrier performance of the silica shell. In vivo, the quantum rattles reduced tumor burden in a single course of photothermal therapy while coupling three complementary imaging modalities: near-infrared fluorescence, photoacoustic, and magnetic resonance imaging. The incorporation of gold within the quantum rattles significantly enhanced the drug-carrier performance of the silica shell. This innovative material design based on the mutually beneficial interaction of gold and silica introduces the use of gold quantum dots for imaging and therapeutic applications.

Lab-on-a-chip synthesis of inorganic nanomaterials and quantum dots for biomedical applications.

The past two decades have seen a dramatic raise in the number of investigations leading to the development of Lab-on-a-Chip (LOC) devices for synthesis of nanomaterials. A majority of these investigations were focused on inorganic nanomaterials comprising of metals, metal oxides, nanocomposites and quantum dots. Herein, we provide an analysis of these findings, especially, considering the more recent developments in this new decade. We made an attempt to bring out the differences between chip-based as well as tubular continuous flow systems. We also cover, for the first time, various opportunities the tools from the field of computational fluid dynamics provide in designing LOC systems for synthesis inorganic nanomaterials. Particularly, we provide unique examples to demonstrate that there is a need for concerted effort to utilize LOC devices not only for synthesis of inorganic nanomaterials but also for carrying out superior in vitro studies thereby, paving the way for faster clinical translation. Even though LOC devices with the possibility to carry out multi-step syntheses have been designed, surprisingly, such systems have not been utilized for carrying out simultaneous synthesis and bio-functionalization of nanomaterials. While traditionally, LOC devices are primarily based on microfluidic systems, in this review article, we make a case for utilizing millifluidic systems for more efficient synthesis, bio-functionalization and in vitro studies of inorganic nanomaterials tailor-made for biomedical applications. Finally, recent advances in the field clearly point out the possibility for pushing the boundaries of current medical practices towards personalized health care with a vision to develop automated LOC-based instrumentation for carrying out simultaneous synthesis, bio-functionalization and in vitro evaluation of inorganic nanomaterials for biomedical applications.

Ligand‐Stabilized and Atomically Precise Gold Nanocluster Catalysis: A Case Study for Correlating Fundamental Electronic Properties with Catalysis

We present results from our investigations into correlating the styrene-oxidation catalysis of atomically precise mixed-ligand biicosahedral-structure [Au25(PPh3)10(SC12H25)5Cl2](2+) (Au25-bi) and thiol-stabilized icosahedral core-shell-structure [Au25(SCH2CH2Ph)18](-) (Au25-i) clusters with their electronic and atomic structure by using a combination of synchrotron radiation-based X-ray absorption fine-structure spectroscopy (XAFS) and ultraviolet photoemission spectroscopy (UPS). Compared to bulk Au, XAFS revealed low Au-Au coordination, Au-Au bond contraction and higher d-band vacancies in both the ligand-stabilized Au clusters. The ligands were found not only to act as colloidal stabilizers, but also as d-band electron acceptor for Au atoms. Au25-bi clusters have a higher first-shell Au coordination number than Au25-i, whereas Au25-bi and Au25-i clusters have the same number of Au atoms. The UPS revealed a trend of narrower d-band width, with apparent d-band spin-orbit splitting and higher binding energy of d-band center position for Au25-bi and Au25-i. We propose that the differences in their d-band unoccupied state population are likely to be responsible for differences in their catalytic activity and selectivity. The findings reported herein help to understand the catalysis of atomically precise ligand-stabilized metal clusters by correlating their atomic or electronic properties with catalytic activity.

Displacement Synthesis of Cu Shells Surrounding Co Nanoparticles

Copper shells were fabricated by a displacement method around Co nanoparticles (3.2 ′ 0.6 nm) at room temperature in a copper-citrate aqueous electrolyte. The nanoparticles were synthesized by a wet chemical approach using the surfactant sulfobetaine, dodecyldimethyl (3-sulfopropyl) ammonium hydroxide (98%) in tetrahydrofuran. X-ray absorption near-edge structure analysis confirmed that cobalt oxide was not present in the nanoparticles upon exposure to air, consistent with a shell formation. Additionally, the presence of the shell resulted in an increase of the blocking temperature of the core-shell nanoparticles, stabilizing the ferromagnetic behavior up to 235 K.

Millifluidics for Time-resolved Mapping of the Growth of Gold Nanostructures

Innovative in situ characterization tools are essential for understanding the reaction mechanisms leading to the growth of nanoscale materials. Though techniques, such as in situ transmission X-ray microscopy, fast single-particle spectroscopy, small-angle X-ray scattering, etc., are currently being developed, these tools are complex, not easily accessible, and do not necessarily provide the temporal resolution required to follow the formation of nanomaterials in real time. Here, we demonstrate for the first time the utility of a simple millifluidic chip for an in situ real time analysis of morphology and dimension-controlled growth of gold nano- and microstructures with a time resolution of 5 ms. The structures formed were characterized using synchrotron radiation-based in situ X-ray absorption spectroscopy, 3-D X-ray tomography, and high-resolution electron microscopy. These gold nanostructures were found to be catalytically active for conversion of 4-nitrophenol into 4-aminophenol, providing an example of the potential opportunities for time-resolved analysis of catalytic reactions. While the investigations reported here are focused on gold nanostructures, the technique can be applied to analyze the time-resolved growth of other types of nanostructured metals and metal oxides. With the ability to probe at least a 10-fold higher concentrations, in comparison with traditional microfluidics, the tool has potential to revolutionize a broad range of fields from catalysis, molecular analysis, biodefense, and molecular biology.

Nanofabrication towards biomedical applications : techniques, tools, applications, and impact

Preface.List of Contributors.I Fabrication of Nanomaterials.1 Synthetic Approaches to Metallic Nanomaterials (Ryan Richards and Helmut Bonnemann).1.1 Introduction.1.2 Wet Chemical Preparations.1.3 Reducing Agents.1.4 Electrochemical Synthesis.1.5 Decomposition of Low-Valency Transition Metal Complexes.1.6 Particle Size Separations.1.7 Potential Applications in Materials Science.2 Synthetic Approaches for Carbon Nanotubes (Bingqing Wei, Robert Vajtai, and Pulickel M. Ajayan).2.1 Introduction.2.2 Family of Carbon Nanomaterials.2.3 Synthesis of Carbon Nanotubes.2.4 Controllable Synthesis of Carbon Nanotube Architectures.2.5 Perspective on Biomedical Applications.2.6 Conclusion.3 Nanostructured Systems from Low-Dimensional Building Blocks (Donghai Wang, Maria P. Gil, Guang Lu, and Yunfeng Lu).3.1 Introduction.3.2 Nanostructured System by Self-Assembly.3.3 Biomimetic and Biomolecular Recognition Assembly.3.4 Template-Assisted Integration and Assembly.3.5 External-Field-Induced Assembly.3.6 Direct Synthesis of 2D/3D Nanostructure.3.7 Applications.3.8 Concluding Remarks.4 Nanostructured Collagen Mimics in Tissue Engineering (Sergey E. Paramonov and Jeffrey D. Hartgerink).4.1 Introduction.4.2 Collagen Structural Hierarchy.4.3 Amino Acid Sequence and Secondary Structure.4.4 Experimental Observation of the Collagen Triple Helix.4.5 Folding Kinetics.4.6 Stabilization Through Sequence Selection.4.7 Stabilization via Hydroxyproline: The Pyrrolidine Ring Pucker.4.8 Triple Helix Stabilization Through Forced Aggregation.4.9 Extracellular Matrix and Collagen Mimics in Tissue Engineering.4.10 Sticky Ends and Supramolecular Polymerization.4.11 Conclusion.5 Molecular Biomimetics: Building Materials Natures Way, One Molecule at a Time (Candan Tamerler and Mehmet Sarikaya).5.1 Introduction.5.2 Inorganic Binding Peptides via Combinatorial Biology.5.3 Physical Specificity and Molecular Modeling.5.4 Applications of Engineered Polypeptides as Molecular Erectors.5.5 Future Prospects and Potential Applications in Nanotechnology.II Characterization Tools for Nanomaterials and Nanosystems.6 Electron Microscopy Techniques for Characterization of Nanomaterials (Jian-Min (Jim) Zuo).6.1 Introduction.6.2 Electron Diffraction and Geometry.6.3 Theory of Electron Diffraction.6.4 High-Resolution Electron Microscopy.6.5 Experimental Analysis.6.6 Applications.6.7 Conclusions and Future Perspectives.7 X-Ray Methods for the Characterization of Nanoparticles (Hartwig Modrow).7.1 Introduction.7.2 X-Ray Diffraction: Getting to Know the Arrangement of Atoms.7.3 Small-Angle X-Ray Scattering: Learning About Particle Shape and Morphology.7.4 X-Ray Absorption: Exploring Chemical Composition and Local Structure.7.5 Applications.7.6 Summary and Conclusions.A.1 General Approach.A.2 X-Ray Diffraction.A.3 Small-Angle Scattering.A.4 X-Ray Absorption.8 Single-Molecule Detection and Manipulation in Nanotechnology and Biology (Christopher L. Kuyper, Gavin D. M. Jeffries, Robert M. Lorenz, and Daniel T. Chiu).8.1 Introduction.8.2 Optical Detection of Single Molecules.8.3 Single-Molecule Manipulations Using Optical Traps.8.4 Applications in Single-Molecule Spectroscopy.8.5 Single-Molecule Detection with Bright Fluorescent Species.8.6 Nanoscale Chemistry with Vesicles and Microdroplets.8.7 Perspectives.9 Nanotechnologies for Cellular and Molecular Imaging by MRI (Patrick M. Winter, Shelton D. Caruthers, Samuel A. Wickline, and Gregory M. Lanza).9.1 Introduction.9.2 Cardiovascular Disease.9.3 Cellular and Molecular Imaging.9.4 Cellular Imaging with Iron Oxides.9.5 Molecular Imaging with Paramagnetic Nanoparticles.9.6 Conclusions.III Application of Nanotechnology in Biomedical Research.10 Nanotechnology in Nonviral Gene Delivery (Latha M. Santhakumaran, Alex Chen, C. K. S. Pillai, Thresia Thomas, Huixin He, and T. J. Thomas).10.1 Introduction.10.2 Agents That Provoke DNA Nanoparticle Formation.10.3 Characterization of DNA Nanoparticles.10.4 Mechanistic Considerations in DNA Nanoparticle Formation.10.5 Systemic Gene Therapy Applications.10.6 Future Directions.11 Nanoparticles for Cancer Drug Delivery (Carola Leuschner and Challa Kumar).11.1 Introduction.11.2 Cancer: A Fatal Disease and Current Approaches to Its Cure.11.3 Characteristics of Tumor Tissues.11.4 Drug Delivery to Tumors.11.5 Physicochemical Properties of Nanoparticles in Cancer Therapy.11.6 Site-Specific Delivery of Chemotherapeutic Agents Using Nanoparticles.11.7 Nonviral Gene Therapy with Nanoparticles.11.8 Hyperthermia.11.9 Controlled Delivery of Chemotherapeutic Drugs Using Nanoparticles.11.10 Nanoparticles to Circumvent MDR.11.11 Potential Problems in Using Nanoparticles for Cancer Treatment.11.12 Future Outlook.12 Diagnostic and Therapeutic Applications of Metal Nanoshells (Christopher Loo, Alex Lin, Leon Hirsch, Min-Ho Lee, Jennifer Barton, Naomi Halas, Jennifer West, and Rebekah Drezek).12.1 Introduction.12.2 Methodology.12.3 Results and Discussion.12.4 Conclusions.13 Decorporation of Biohazards Utilizing Nanoscale Magnetic Carrier Systems (Axel J. Rosengart and Michael D. Kaminski).13.1 introduction.13.2 Technological Need.13.3 Technical Basis.13.4 Technology Specifications.14 Nanotechnology in Biological Agent Decontamination (Peter K. Stoimenov and Kenneth J. Klabunde).14.1 Introduction.14.2 Standard Methods for Chemical Decontamination of Biological Agents.14.3 Nanomaterials for Decontamination.14.4 Magnesium Oxide.14.5 Mechanism of Action.14.6 Titanium Dioxide.14.7 Summary.IV Impact of Biomedical Nanotechnology on Industry, Society, and Education.15 Too Small to See: Educating the Next Generation in Nanoscale Science and Engineering (Anna M. Waldron, Keith Sheppard, Douglas Spencer, and Carl A. Batt).15.1 Introduction.15.2 Nanotechnology as a Motivator for Engaging Students.15.3 The Nanometer Scale.15.4 Understanding Things Too Small to See.15.5 Creating Hands-On Science Learning Activities to Engage the Mind.15.6 Things That Scare Us.15.7 The Road Ahead.16 Nanobiomedical Technology: Financial, Legal, Clinical, Political, Ethical, and Societal Challenges to Implementation (Steven A. Edwards).16.1 Introduction.16.2 Drexler and the Dreaded Universal Assembler.16.3 Financial.16.4 Legal and Regulatory.16.5 Operational.16.6 Clinical.16.7 Political, Ethical And Social Challenges.16.8 Summary.Abbreviations.Index.

The influence of various coatings on the electronic, magnetic, and geometric properties of cobalt nanoparticles (invited)

From the results reported here for Co nanoparticles coated with 3-(N,N-dimethyl-dodecylammonium)- propanesulfonate (SB12), Cu, or Au, and from experimental and theoretical results published by several other groups there is strong evidence that the various coatings (organic as well as inorganic) not just influence but even determine the properties of small metallic nanoparticles. In an empirical manner, the core-coating interaction is already used to influence the size and the shape of nanoparticles. Based on previously published results and some experiments, in this paper the influence is described that various coatings have on the geometric, electronic, and magnetic properties of cobalt nanoparticles with diameters smaller than 10nm. The results indicate that there is an interdependence of various properties (e.g., size and electronic properties of a particle with the same coating) so that is seems to be difficult to vary one property in a systematic way without changing others.