Amit Singh

Bio: Amit Singh is an academic researcher from University of Florida. The author has contributed to research in topics: Photothermal therapy & Preclinical imaging. The author has an hindex of 8, co-authored 13 publications receiving 691 citations.

Nanoparticles as contrast agents for in-vivo bioimaging: current status and future perspectives

Abstract: Nanoparticle-based contrast agents are quickly becoming valuable and potentially transformative tools for enhancing medical diagnostics for a wide range of in-vivo imaging modalities. Compared with conventional molecular-scale contrast agents, nanoparticles (NPs) promise improved abilities for in-vivo detection and potentially enhanced targeting efficiencies through longer engineered circulation times, designed clearance pathways, and multimeric binding capacities. However, NP contrast agents are not without issues. Difficulties in minimizing batch-to-batch variations and problems with identifying and characterizing key physicochemical properties that define the in-vivo fate and transport of NPs are significant barriers to the introduction of new NP materials as clinical contrast agents. This manuscript reviews the development and application of nanoparticles and their future potential to advance current and emerging clinical bioimaging techniques. A focus is placed on the application of solid, phase-separated materials, for example metals and metal oxides, and their specific application as contrast agents for in-vivo near-infrared fluorescence (NIRF) imaging, magnetic resonance imaging (MRI), positron emission tomography (PET), computed tomography (CT), ultrasound (US), and photoacoustic imaging (PAI). Clinical and preclinical applications of NPs are identified for a broad spectrum of imaging applications, with commentaries on the future promise of these materials. Emerging technologies, for example multifunctional and theranostic NPs, and their potential for clinical advances are also discussed.

Polyhydroxy Fullerenes for Non‐Invasive Cancer Imaging and Therapy

Abstract: DOI: 10.1002/smll.201000847 Nanoparticle-mediated, image-guided cancer therapy has tremendous promise for increasing the effi cacy of cancer treatment while reducing toxic side effects traditionally associated with treatment. Carbon nanotubes and metal-based nanomaterials are leading candidates for image-guided therapy in cancer nanotechnology. [ 1–5 ] However, limited solvent compatibility, non-biodegradability and concerns over the safety of these nanomaterials may hinder their commercialization. Here, we show that the photothermal and photoacoustic properties of polyhydroxy fullerenes [ 6 ] (PHF)—which are water-soluble, biodegradable, [ 7 ] antioxidant, [ 8–10 ] and rapidly excreted [ 11 ] —can be applied for imaging and therapy of cancer. Biodegradable PHF-containing chitosan nanoparticles provided excellent photoacoustic contrast. Tumors injected with PHF nanoparticles and exposed to near infrared laser decreased in cross-sectional area by an average of 32% within two hours of treatment, with only a blister visible 20 hours post-treatment. We anticipate that photoacoustic and photothermal properties of PHF along with their other therapeutic properties [ 12–15 ] will enable safe, non-invasive image-guided therapy of cancer with minimal side-effects. Polyhydroxy Fullerenes for Non-Invasive Cancer Imaging and Therapy

Multi-dye theranostic nanoparticle platform for bioimaging and cancer therapy.

Abstract: Background Theranostic nanomaterials composed of fluorescent and photothermal agents can both image and provide a method of disease treatment in clinical oncology. For in vivo use, the near-infrared (NIR) window has been the focus of the majority of studies, because of greater light penetration due to lower absorption and scatter of biological components. Therefore, having both fluorescent and photothermal agents with optical properties in the NIR provides the best chance of improved theranostic capabilities utilizing nanotechnology.

Kinetics of liquid annulus formation and capillary forces.

Abstract: The dependence of the capillary adhesion force Fcap between a silica microsphere and a flat silica surface versus a time period t of the samples’ contact (i.e., dwell-in time) is experimentally inv...

Multimodal nanoparticulate bioimaging contrast agents.

Abstract: A wide variety of bioimaging techniques (e.g., ultrasound, computed X-ray tomography, magnetic resonance imaging (MRI), and positron emission tomography) are commonly employed for clinical diagnostics and scientific research. While all of these methods use a characteristic "energy-matter" interaction to provide specific details about biological processes, each modality differs from another in terms of spatial and temporal resolution, anatomical and molecular details, imaging depth, as well as the desirable material properties of contrast agents needed for augmented imaging. On many occasions, it is advantageous to apply multiple complimentary imaging modalities for faster and more accurate prognosis. Since most imaging modalities employ exogenous contrast agents to improve the signal-to-noise ratio, the development and use of multimodal contrast agents is considered to be highly advantageous for obtaining improved imagery from sought-after imaging modalities. Multimodal contrast agents offer improvements in patient care, and at the same time can reduce costs and enhance safety by limiting the number of contrast agent administrations required for imaging purposes. Herein, we describe the synthesis and characterization of nanoparticulate-based multimodal contrast agent for noninvasive bioimaging using MRI, optical, and photoacoustic tomography (PAT)-imaging modalities. The synthesis of these agents is described using microemulsions, which enable facile integration of the desired diversity of contrast agents and material components into a single entity.

Gold nanoparticles in biomedical applications: recent advances and perspectives

Abstract: Gold nanoparticles (GNPs) with controlled geometrical, optical, and surface chemical properties are the subject of intensive studies and applications in biology and medicine. To date, the ever increasing diversity of published examples has included genomics and biosensorics, immunoassays and clinical chemistry, photothermolysis of cancer cells and tumors, targeted delivery of drugs and antigens, and optical bioimaging of cells and tissues with state-of-the-art nanophotonic detection systems. This critical review is focused on the application of GNP conjugates to biomedical diagnostics and analytics, photothermal and photodynamic therapies, and delivery of target molecules. Distinct from other published reviews, we present a summary of the immunological properties of GNPs. For each of the above topics, the basic principles, recent advances, and current challenges are discussed (508 references).

Toxicity of nanomaterials

Abstract: Nanoscience has matured significantly during the last decade as it has transitioned from bench top science to applied technology. Presently, nanomaterials are used in a wide variety of commercial products such as electronic components, sports equipment, sun creams and biomedical applications. There are few studies of the long-term consequences of nanoparticles on human health, but governmental agencies, including the United States National Institute for Occupational Safety and Health and Japan's Ministry of Health, have recently raised the question of whether seemingly innocuous materials such as carbon-based nanotubes should be treated with the same caution afforded known carcinogens such as asbestos. Since nanomaterials are increasing a part of everyday consumer products, manufacturing processes, and medical products, it is imperative that both workers and end-users be protected from inhalation of potentially toxic NPs. It also suggests that NPs may need to be sequestered into products so that the NPs are not released into the atmosphere during the product's life or during recycling. Further, non-inhalation routes of NP absorption, including dermal and medical injectables, must be studied in order to understand possible toxic effects. Fewer studies to date have addressed whether the body can eventually eliminate nanomaterials to prevent particle build-up in tissues or organs. This critical review discusses the biophysicochemical properties of various nanomaterials with emphasis on currently available toxicology data and methodologies for evaluating nanoparticle toxicity (286 references).

The unique role of nanoparticles in nanomedicine: imaging, drug delivery and therapy

Abstract: This critical review will present the role of nanoparticles (NPs) in the directions that are vital to the new field of nanomedicine, including imaging and drug delivery. We reflect on the physical properties that make NPs advantageous for in vivo efficacy, and review recent advances in major NP based biomedical applications. Critical questions of transport, uptake, and clearance will be discussed and illustrated through the success and opportunities of NP imaging and therapy on a photodynamic therapy (PDT) based NP system that has been developed in our lab over the past decade (540 references).